THE PETROLOGY, PETROGRAPHY AND GEOCHEMISTRY OF ANOMALOUS BOREHOLE CORE SEQUENCES IN THE HIGHVELD COALFIELD, SOUTH : A CASE STUDY FOR DIATREME ACTIVITY.

by

BYRON VANDER WALT

Submitted in fulfilment of the requirements for the degree

MAGISTER SCIENTAE

in

GEOLOGY

submitted to the

FACULTV OF SCIENCE

of the

UNIVERSITY OF JOHANNESBURG

July 2012

SUPERVISORS: PROFESSOR B. CAIRNCROSS PROFESSOR H.M. RAJESH ABSTRACT

Three anomalous borehole core sequences from the north eastern Karoo Basin are examined. The boreholes are located up to 30 km from each other and are lithostratigraphically completely atypical for the Vryheid Formation, ,

Karoo Supergroup. The lithologies of the three boreholes are intensely brecciated for the most part, while all of the surrounding boreholes reveal normal stratigraphy; their sedimentary strata are normally horizontal with no faulting present. The only known disturbances to the Vryheid Formation in the study area are the occurrence of intrusive mafic dolerite sills and dykes, which are known to have been contemporaneous with and immediately following the eruption of the Drakensburg

Group basaltic lavas.

The borehole core lithologies are described in detail with reference to their textural, mineralogical and petrographic characteristics. Mineral and bulk rock chemical data are presented. Several modes of origin of the brecciated core sequences are considered, with the primary hypothesis that the brecciation is due to diatreme activity. A review of diatremes and their mode of emplacement is proposed with reference to their occurrence within the Karoo Igneous Province, as some diatremes in the Karoo are associated with dolerite sill emplacement. The isolated occurrences, lithologies, petrography, alteration and geochemistry of the sequences are used to argue that the Vryheid Formation, intersected in the form of the three anomalous boreholes, was disturbed by diatreme activity, which are genetically related to the late dolerite sill emplacement into the rocks. ACKNOWLEDGEMENTS

Anglo Geological Services are acknowledged for providing core samples and other geological data for this thesis. Thanks to Mr. F. Botes, Mrs. U. Herrmann, Mr.

M. Mattushek, Mr. J. Ndwamise and Mrs. J. Marks and all members of Anglo Coal

Geological Services who assisted either directly or indirectly with the preparation of this study.

Thanks go to the Coaltech Research Association and the National Research

Foundation (NRF) for the financial support for this study.

I am grateful to the following members of the Department of Geology at the

University of Johannesburg:

1. Professor Bruce Cairncross, my supervisor, for all his guidance with this study,

for his advice, assistance, editorial skills, the use of his photographic

equipment, as well as approving this thesis.

2. Professor H.M. Rajesh, my co-supervisor, for all his assistance and for sharing

his knowledge and expertise in the fields for igneous petrology, mineral

chemistry and geochemistry.

3. Professor Fanus Viljoen, for his advice in many respects, as well as for

assisting me with the use of the binocular microscope and camera used in the

project.

4. Dr. Herman van Niekerk, for his advice and friendship.

5. Dr. Christian Reineke, for his assistance in using the Jeol 733 Superprobe.

I would like to thank my parents David and Wilma for their support throughout all my studies and for always being there for me.

I am most grateful to Nicola Skerman for always providing me with encouragement and support.

ii TABLE OF CONTENTS

Page No.

CHAPTER 1 - INTRODUCTION 1

1.1 Coal in 1

1.2 Location 2

1.3 Objectives and Methodology 5

1.3.1 Problem Identification 5

1.3.2 Objectives 5

1.3.3 Methodology 5

1.4 Regional Geology 7

1.4.1 The Karoo Supergroup 7

1.4.2 The Karoo Igneous Province 13

1.5 Past Studies 17

CHAPTER 2- STRATIGRPHY 22

2.1 Stratigraphy of the Vryheid Formation and the Highveld Coalfield 22

2.2 Genetic stratigraphy of the Highveld Coalfield 24

2.3 Stratigraphy of the study area 27

CHAPTER 3- PETROLOGY, PETROGRAPHY AND MINERAL CHEMISTRY 42

3.1 The undeformed lithofacies in the study area 42

3.2 Petrography 51

3.2.1 Introduction 51

3.2.2 Sample Selection 51

3.2.3 Petrography of the brecciated core sequences 54 3.3 Mineral Chemistry 62 3.3.1 Introduction 62 3.3.2 Methodology 62

3.3.3 Mineral chemistry of the unaltered dolerites from the standard

core sequence 63

iii 3.3.4 Mineral chemistry of the altered dolerites from the standard

core sequence 65

3.3.5 Mineral chemistry of the sedimentary rocks and breccia 69

3.4 Discussion on the nature of the brecciation in Core A and Core B 71

CHAPTER 4 - GEOCHEMISTRY 75

4.1 Introduction 75

4.2 Methodology 75

4.3 Geochemistry of the unaltered and altered dolerites 77

4.3.1 Classification and tectonic setting 77

4.3.2 Comparison of geochemical characteristics of dolerite samples 83

4.3 Bulk rock geochemistry of fresh sedimentary rocks and the breccia matrix 95

4.3.1 Classification and tectonic setting 95

4.3.2 Comparison of geochemical characteristics of fresh sedimentary

rocks and the breccia matrix 97

CHAPTER 5- STABLE ISOTOPES 107

5.1 Introduction to stable isotopes 107

5.2 Methodology 108

5.3 Stable isotope data 108

CHAPTER 6 - DISCUSSION 112

6.1 Possible modes of origin of the brecciated core sequences 112

6.1.1 Fault breccias 112

6.1.2 Sinkhole Collapse 112

6.1.3 Meteorite impact 113

6.1.4 Syn-sedimentary deformation 113

6.1.5 Diatreme activity 113

6.2 A review on diatremes 114

6.3 Evidence to support a diatreme model 117

6.3.1 The isolated occurrences of the brecciated borehole core

sequences 117

iv 6.3.2 The lithologies of the brecciated borehole core sequences 118

6.3.3 Sediment fluidization 118

6.3.4 Variations with depth 119

6.3.5 Mineral chemical and geochemical implications 119

6.3.6 Stable isotope discrepancies 120

6.3.7 Lithological implications of a diatreme model 122

CHAPTER 7 - CONCLUSIONS 124

7.1 Motivation for a diatreme model 124

7.2 Proposed model for the formation of the brecciated core sequences 124

7.3 Time constraints for diatreme formation 125

7.4 Conclusion 125

7.5 Future studies and implications to mining activity 126

REFERENCES 127

APPENDIX A

Full descriptions of the petrology and petrography of brecciated core sequence A. 140

APPENDIX B

Full descriptions of the petrology and petrography of brecciated core sequence B. 190

APPENDIX C

Petrology and petrography of representative samples from the standard core sequence. 232

APPENDIX D

Mineral chemical analyses of the Standard Core and brecciated core sequences. 249

APPENDIX E Geochemical analyses of the Standard Core and Brecciated Core sequences. 261

v LIST OF FIGURES

Page No. Figure 1.1 Locality map of the study area. 3

Figure 1.2 The distribution of the Karoo-type Basins of Southern Africa and location of the study area within the main Karoo Basin 4

Figure 1.3 The approximate relative positions of the anomalous boreholes found. 6

Figure 1.4 The areal distribution of the lithostratigraphic units in the Karoo Basin. 8

Figure 1.5 North-south cross-sections across the Karoo Basin. 11

Figure 1.6 A palaeogeographic reconstruction with major depositional environments during the No.4 seam peat accumulations 11

Figure 1.7 Map of the Karoo Igneous Province of southern Africa 14

Figure 1.8 The distribution of known diatremes and "breccia pipes" in the Karoo Basin 17

Figure 2.1 Schematic north-south section through the north-eastern part of the Ecca Group. 23

Figure 2.2 Typical and simplified stratigraphic columns in the Highveld Coalfield. 24

Figure 2.3 A typical composite stratigraphic column for the Highveld Coalfield. 26

Figure 2.4 A typical stratigraphic column for the study area. 28

Figure 2.5 The effect of pre-Karoo basement paleotopographic highs. 29

Figure 2.6 The locations of the cross-sections and fence diagram through brecciated core sequence A. 30

Figure 2.7 North-south cross section through brecciated core sequence A. 31

Figure 2.8 Southwest-northeast cross section through brecciated core sequence A. 32

Figure 2.9 Fence diagram through brecciated core sequence A. 33

vi Figure 2.10 The locations of the cross-sections and fence diagram through brecciated core sequence B. 34

Figure 2.11 Northwest-southeast cross section through brecciated core sequence B. 35

Figure 2.12 Southwest-northeast cross section through brecciated core sequence B. 36

Figure 2.13 Fence diagram through brecciated core sequence B. 37

Figure 2.14 The locations of the cross-sections through brecciated core sequence C. 38

Figure 2.15 North-south cross section through brecciated core sequence C. 39

Figure 2.16 East-west cross section through brecciated core sequence C. 40

Figure 2.17 Fence diagram through brecciated core sequence C. 41

Figure 3.1 Roundness and sphericity scale 43

Figure 3.2 Examples of the facies types found in the study area. 49

Figure 3.3 Location of samples taken within brecciated core sequence A. 52

Figure 3.4 Location of samples taken within brecciated core sequence B. 53

Figure 3.5 Representative breccia samples from Core A. 56

Figure 3.6 Representative breccia samples from Core B. 57

Figure 3.7 Unaltered dolerite core samples from the upper sections of Core A and Core B. 59

Figure 3.8 Photomicrographs of the unaltered dolerite core samples from the upper sections of Core A and Core B. 59

Figure 3.9 Comparison of unaltered and altered dolerite using cut sections of core. 60

Figure 3.10 Photomicrographs comparing unaltered and altered dolerite. 61

Figure 3.11 BSE images of the unaltered dolerites. 64

Figure 3.12 Ternary diagrams showing feldspar and pyroxene crystal compositions from the dolerite samples of the standard core sequence. 65

vii Figure 3.13 Backscattered scanning electron images of altered dolerite from the brecciated core sequences. 67

Figure 3.14 Compositions feldspars crystals from Core A and Core B. 68

Figure 3.15 Compositions pyroxene crystals from Core A and Core B. 68

Figure 3.16 Backscattered scanning electron images of the sedimentary rock samples. 70

Figure 3.17 A comparison of the three brecciated core sequences plotted with reference to the theoretical position of the No.4 coal seam. 72

Figure 3.18 Groupings of similar sections in brecciated borehole core sequences A and B. 7

Figure 4.1 Classification diagrams for the altered and unaltered dolerite samples. 77

Figure 4.2 Plots of incompatible element ratios and AFM classification for the unaltered and altered dolerite samples. 79

Figure 4.3 Alteration box plot showing the degree and potential types of alteration of the dolerites samples. 80

Figure 4.4 Photomicrographs showing alteration via the replacement of primary minerals. 81

Figure 4.5 Discriminant function tectonomagmatic discrimination diagrams for the unaltered and altered dolerite samples. 82

Figure 4.6 Plots of major elements vs. Mg# for the unaltered and altered dole rites. 84

Figure 4.7 Plots of selected trace elements vs. Mg# for the unaltered and altered dolerites samples. 85

Figure 4.8 Chondrite-normalised REE diagrams for the unaltered and altered dolerites samples. 86

Figure 4.9 N-MORB-normalized multi-element diagrams for the unaltered and altered dolerites samples. 87

Figure 4.10 Multi-element diagrams for dolerite samples from Core A and Core B normalised to the average values from the standard core. 88

viii Figure 4.11 Enrichment-depletion diagram for Core A dolerites, normalised to the average values from the standard core. 89

Figure 4.12 Enrichment-depletion diagram for Core B dolerites, normalised to the average values from the standard core. 90

Figure 4.13 lsocon Diagrams for Core A samples. 93

Figure 4.14 lsocon Diagrams for Core B samples. 94

Figure 4.15 Sedimentary rock classification diagram (Pettijohn et a/.,1972). 96

Figure 4.16 Sedimentary rock classification diagram (Herron, 1988). 96

Figure 4.17 La-Th-Sc and Th-Co-Zr/10 ternary plots, showing the discriminating fields for the standard sedimentary rocks and breccia matrix samples. 97

Figure 4.18 Plots of major elements vs. Si02 for standard sedimentary rocks and breccia matrix samples. 98

Figure 4.19 Plots of selected trace elements of standard sedimentary rocks and breccia matrix samples. 99

Figure 4.20 Additional trace element variation diagrams of for the selected trace elements for the standard sedimentary rocks and breccia matrix samples. 100

Figure 4.21 Rb-Sr diagram illustrating the maturity if the standard sedimentary rocks and breccia matrix samples and MgO-CaO plot indicating their elevated concentrations relative to the standards. 100

Figure 4.22 REE patterns of the standard sedimentary rocks and breccia matrix samples normalised to Post-Achean Australian Shale (PAAS). 101

Figure 4.23 REE patterns of the sediments and breccia matrix samples normalised to the average of the standard samples. 102

Figure 4.24 Multi-element diagrams for the standard sedimentary rocks and breccia matrix samples normalised to Post-Achean Australian Shale (PAAS). 103

Figure 4.25 Multi-element diagrams for breccia matrix samples from Core A and Core B normalised to the average values from the standard core. 104

ix Figure 4.26 Enrichment-depletion diagram for Core A breccia matrix samples, normalised to the average values from the standard core. 105

Figure 4.27 Enrichment-depletion diagram for Core B breccia matrix samples, normalised to the average values from the standard core. 106

18 13 Figure 5.1 Scatter plots of o 0sMOW and o Cpos for calcites from the standard core and brecciated core sequences. 109

Figure 5.2 13C/12C and 180/60 rations of important carbon and oxygen containing compounds. 111

Figure 6.1 Schematic diagrams of idealised diatremes. 116

Figure 6.2 Depth of intrusion vs. permeability of country rock diagram. 123

X LIST OF TABLES

Table 1.1 The lithostratigraphic subdivision of the Karoo Supergroup. 9

Table 1.2 The formal stratigraphic units of the Karoo Igneous Province. 14

Table 2.1 An informal genetic stratigraphy for the Highveld Coalfield. 25

Table 3.1 The Udden-Wentworth grain size scale. 43

Table 3.2 Facies and sub-facies in the study area. 46

Table 4.1 Major element data of the dolerite samples for the Standard Core, Core A and Core B. 78

Table 4.2 Sum of the trace elements for the Standard Core, Core A and Core B. 88

Table 4.3 Scaling factors used in construction of isocon diagrams. 92

Table 4.4 Major element data of the standard sedimentary rocks samples and breccia matrix samples for the Standard Core, Core A and Core B. 95

Table 5.1 Isotopic composition of carbonates from the standard core and brecciated core sequences. 109

Table 6.1 Re-calculated permeability's (m2s-1) of the sedimentary rocks of the Vryheid Formation. 123

xi CHAPTER 1

INTRODUCTION

1.1 Coal in South Africa

Coal is a readily combustible black to brownish-black, brittle sedimentary rock which contains a large proportion (over 50% by mass) of carbonaceous materials (Snyman,

1998). It is formed by the subaqueous accumulation, compaction and partial decay of plant detritus in oxygen-poor environments, before it undergoes burial (4 -10 km) and is transformed via biological and chemical reactions into coal. An array of occur naturally due to differences in plant material (coal type), degree of metamorphism (coal rank), and amount of non-combustible impurities the coal contains (coal grade).

South Africa's energy resource base is dominated by coal, due to the fact that the country is host to abundant coal supplies at affordable prices (Steyn and Minnitt,

2010a; 2010b). Coal is mined with varying degrees of sophistication, from local individuals for rural households, to some of the world's largest opencast and underground collieries (Cairncross, 2001). It is produced locally for power generation, for export, synfuels and the domestic market (Cadle et a/., 1993;

Cairncross, 2001; lkaneng, 2008; Steyn and Minnitt, 2010a). Local coal production has risen steadily since 1999 to meet increasing demand, with local sales increasing from 154.6 Mt in 1999 to 197.1 Mt by 2008, whilst export sales figures reveal a decreasing trend since 1999 from 66.2 Mt to 57.9 Mt (lkaneng, 2008).

In South Africa, coal is distributed across five geographical provinces and is contained within the rocks of the Karoo Supergroup (Cadle et a/., 1993; Johnson, 1991; Johnson eta/., 1997, 2006; Snyman and Botha, 1993; Snyman, 1998; Tankard et a/., 1982; Winter, 1985). These coalfields are found within the -aged

Vryheid Formation of the Ecca Group. South African coals, particularly those of the

Vryheid Formation, accumulated on a relatively stable continental margin, thus they have been relatively unaffected by deep burial metamorphism and tectonic stress

(Cadle eta/., 1993). Coalfields of particular importance are the Coalfield and

1 Highveld Coalfield, located in Mpumalanga province in north eastern South Africa, which remain the largest producing coalfields in the country (lkaneng, 2008;

Snyman, 1998).

Generally, five coal seams are relatively continuous across most of South Africa's northern Karoo basin coalfields which are almost undisturbed by tectonic movement (Cadle et a/., 1993; Cairncross, 2001; Snyman, 1998). Glossopteris flora provided much of the organic matter that was needed; they were the primary contributor of plant material for the formation of the coal seams (Cadle eta/., 1993; Falcon, 1989;

Rayner, 1995). Lower coal seams are enriched in inertinite and semi-reactives (Cadle eta/., 1993; Falcon, 1989; Falcon and Ham, 1988) and upper coal seams are enriched in vitrinite (up to 60%) (Fabianska and Kruszewska, 2003). The coal seams are currently mined by more than forty operating collieries, including Anglo Coal, which produces coal for 's (http://www.angloamerican.co.za).

Other major coal operators are BHP Billiton Energy South Africa, Exxaro,

Mining and Xstrata Coal (lkaneng, 2008).

The strata of the Karoo Supergroup contain numerous mafic sills and dykes of doleritic composition which are known to have intruded contemporaneously with and immediately following the eruption of the Drakensburg Group basaltic lavas

(Johnson et a/., 1997; Walker and Poldervaart, 1949). The areas surrounding the study area contain many mafic sills and dykes (Stanimirovic, 2002). These intrusions, as in other coalfields (de Oliveira, 1997), can create difficulties in mining. They may negatively affect coal quality, whilst causing rapid lateral variations in coal rank (Cadle et a/., 1993; de Oliveira, 1997; Snyman, 1998). Therefore it is important to maintain a high level of understanding of the mining area via extensive drilling operations and core logging.

1.2 Location

The study area is geographically located between the town of Secunda to the north and Standerton to the south, approximately 150 km south-east of Johannesburg, within the Mpumalanga Province in South Africa (Figure 1.1). Geologically, the study

2 area is situated in the north eastern portion of the Karoo Basin within the Highveld

Coalfield, south of the Witbank coalfield (Figure 1.2). This area comprises a succession of clastic sedimentary rocks of the Vryheid Formation, Ecca Group of the

Karoo Supergroup.

500 . km ...

LEGEND Study area /Roads e Towns • Dams

N f o...... ____.zokm

Figure 1.1- Locality map ofthe study area.

3 N t \

...

,..

.. ,,,,.,~ :: -JZ" ,~ 32" EASTERN ,CAPE

100 200 km ~=1S-=:=- }h EJ EccoG• .,.,...._ ~ ...... w ~1.. '

Figure 1.2- The distribution of the Karoo-type Basins of Southern Africa showing the location of the study area within the main Karoo Basin (modified after Johnson et al., 2006). The inset shows the distribution of major coalfields in South Africa, including the location of the study area. 1. Tuli, 2. Ellisras, 3. Mopane, 4. Tshipise, 5. Pafuri, 6. Spingbok Flats, 7. Witbank, 8. Kangwane, 9. Free State, 10. Vereeniging-Sasolburg, 11. South Rand, 12. Highveld, 13. Ermelo, 14. Klip River, 15. Utrecht, 16. Vryheid, 17. Nongoma, 18. Somkele, 19. Molteno­ lndwe (modified after Snyman, 1998).

4 1.3 Objectives and Methodology

1.3.1 Problem Identification

Drilling forms part of the routine exploration, quality control, and mine planning of

any colliery. It was during such a routine drilling operation that three anomalous

borehole core sequences were intersected in the study area (see Figure 1.3). The

sequences were completely atypical for those of the area and the Vryheid Formation

in general (SACS, 1980; Snyman, 1998; Stanimirovic, 2002). The lithologies of the

boreholes were intensely brecciated for the most part, while all of the surrounding

boreholes revealed normal stratigraphy, i.e., the sedimentary strata are typically

horizontal with little or no faulting present. The cause for the highly isolated nature

of the brecciated core is unknown and investigating these anomalies is of academic

and commercial interest. Five possible origins are considered to explain the

brecciation of the succession and the most probable scenario is examined.

1.3.2 Objectives

The primary objective of the study was to test the hypothesis that the brecciated

cores are due to post-Karoo diatreme activity, and if so, to determine whether the

diatremes are magmatic or phreatomagmatic in origin. In order to validate this

hypothesis, the breccias must contain juvenile magmatic components, related to the

explosive event, in addition to other typical characteristics of diatreme breccias

(Lorenz and Kurszlaukis, 2007; Svensen et a/., 2006). If the hypothesis failed,

alternative scenarios, such as faulting, sinkhole collapse, meteorite impact, and syn

sedimentary deformation, which have been briefly proposed in the past (Cairncross, 1998), would be considered.

1.3.3 Methodology

The three borehole logs for brecciated borehole core sequences A, B and C were

made available for this study by the colliery working in the area. Two of the three brecciated borehole core sequences were also made available (Core A and Core B).

The locations of the brecciated borehole core sequences are shown in Figure 1.3.

5 ~ N D Studyarea • Locations of t anomalous boreholes Approximate extent 0 of boreholes used • ~~~eJgr:ed, standard (core sampled)

10 15 20 I I lkm

Figure 1.3 - Localities of the brecciated boreholes. The approximate extent of borehole logs used in this study is shown in addition to the location of the standard borehole core used. Core A, Core Band Core Care the borehole names used for the brecciated sequences.

The first core sequence was intersected some 14 years ago (1997) and sampled by

Cairncross (1998) at the time. It has been logged as brecciated core sequence A (or

Core A). Core samples were collected with the intention that some research could be undertaken to establish the cause of the fragmentation of the sequence. The results achieved at the time were in the form of a short, internal report describing the core in general with some mention as to its possible origin (Cairncross, 1998). The second brecciated core sequence was intersected in 2008 and was sampled by a mine geologist. It has been labelled brecciated core sequence B (or Core B).

For both Core A and Core B, selected core samples were taken from specific zones of interest within the sequence and the samples stratigraphic position within the sequence was recorded. All core samples for this study were collected from the relevant persons, cleaned and photographed, and then examined and described in detail.

Although the third brecciated core sequence was unavailable for sampling, a detailed borehole core log was available. This sequence has been labelled brecciated core sequence C (or Core C). Apart from the three anomalous borehole logs, 110

6 surrounding boreholes were also made available by the colliery and used to construct detailed borehole cross-sections and fence diagrams, thereby providing a better understanding of the adjacent stratigraphy (Figure 1.3).

The brecciated core samples (15x samples per core sequence) were sawn in half, photographed and selected samples were used for making thin sections. The thin sections were described using optical microscopy before an electron microprobe was used for mineral chemical investigations. Petrographic studies were accompanied by detailed bulk geochemical analysis (major, trace, and REE) of selected core samples

(lOx dolerite and 5x breccia samples per core sequence), to ascertain their nature, chemical composition and possible origin. Stable isotope data of calcite veins present in the sequences were obtained for analysis (lx Core A and 8x Core B calcite samples). The same procedure (as outlined above), was applied to a core sequence of normal, undeformed core (Figure 1.3) from the study area for comparative purposes. Detailed information regarding the sampling and analytical procedures followed is provided in the relevant chapters.

1.4 Regional Geology

1.4.1 The Karoo Supergroup

The rocks of the Karoo Supergroup cover approximately two thirds of the country of the Republic of South Africa (Johnson et a/., 2006). The shape and location of the basin relative to an inferred magmatic arc in the south reveal that this basin is a wedge shaped, retroarc foreland basin which is in excess of 6 km thick in the southern regions (Cadle et a/., 1990, 1993; Catuneanu et a/., 1998, 2002, 2005; Johnson eta/., 2006). It is comprised primarily of clastic rocks with lesser amounts of extrusive and intrusive igneous rocks. The sediments were deposited into the south­ westerly dipping Karoo Basin, between the late Carboniferous and Middle Triassic

(Catuneanu et a/., 2002, 2005; Johnson et a/., 1997) with lavas pouring out and capping the sediments during the Jurassic.

7 The Karoo Basin borders the front of the Cape Fold Mountains and the lithologies pinch out to the north overlapping onto the (Cadle et a/., 1993).

The Karoo Sea which once filled the basin covered an area of approximately

2 1,500,000 km • Today its remaining deposits cover an area of approximately 550,000 km 2 (Cadle et a/., 1990, 1993). The erosional remnants outcrop with the major lithologies forming more or less concentric patterns younging centripetally towards Lesotho (Johnson eta/., 1997) as shown in Figure 1.4.

The lithologies present in the Karoo Basin reveal an evolution from basal glacial to uppermost temperate to arid climatic conditions (Cadle et at., 1993; Smith et a/., 1993; Tankard et a/., 1982). The basin underwent changes from one dominated by a marine environment, through a transitional environment, then through a fluvial dominated environment, to more lacustrine, semi-arid and arid environments

(Catuneanu et at., 2002; Johnson et at., 1997). The lithostratigraphic subdivisions of the Karoo Supergroup are shown in Table 1.1.

- Orakensberg Group Molteno, Elliot & Clarens Formations L; n - CJ EccaGroup -

""'o -=d'!'!!!:::::=~2f0 km

Figure 1.4 - The areal distribution of lithostratigraphic units in the Karoo Basin. See Figure 1.5 for the cross section marked by the north-south/southwest line (modified after Johnson eta/., 1997).

8 Vl -I SUPERGROUP GROUP SUBGROUP )> Ill i ~ n I'D I i.n South Western Eastern Cape Kwazulu-Natal Tshipise Pafuri ...... \.0 Cape Province Province Area 00 ' I .9 -I ~ Lembo Drakensburg Moveni Letaba I'D ~ Jozini ~ 0 V> ...... Clarens Clarens Nyoka Clarens ..... Ill ...... Bosbokpoort 06" Stormberg Elliot Ntanene ..... Ill "C Klopperfontein ~ Molteno n· Solitude V> Tarkastad Burgersdorp !:: c- Karoo a. Katberg

• The Dwyka Group forms the lowermost part of the Karoo succession. The

sediments comprising the group are considered to be glacial in origin and

were deposited during the Late Carboniferous to the Early Permian (Cadle et a/., 1990). The rocks of the Dwyka Group rest unconformably on the ancient

Precambrian bedrock in the north, often showing distinct erosional surfaces

formed by glaciations (von Brunn, 1977); in the south and east they

unconformably overlie strata of the Cape Supergroup and Natal Groups

respectively (Figure 1.5). A number of lithofacies are recognised by Visser

(1986). These contain massive and stratified diamictites deposited by

continental and marine ice sheets during the Late Carboniferous (Johnson et

a/., 2006), subglacial till, glaciolacustrine till and fluvioglacial outwash

deposits (Cadle et a/., 1990; Visser, 1986). Associated lithofacies include

glaciofluvial conglomerates, sandstones and glaciolacustrine mudrocks. The

transition from the Dwyka Group to the overlying Ecca Group is, for the most

part, an abrupt but diachronous contact representing an environmental

change, from melt water influenced alluvial fans issuing into a euxinic lake to

more stable lower-energy fluvial systems building out fine-grained deltas into a sea (Smith et.al., 1993).

• The Ecca Group forms a southward-thickening prism of clastic sedimentary

strata, consisting mainly of mudrock, shale and sandstone deposited during the Permian (Hobday, 1978; Johnson et a/., 1997; Tankard et a/., 2009) (Figure 1.5). Basin infilling of much of the Karoo Basin occurred during this

period, particularly in the deeper areas located in the southern parts of the basin via turbidites (Flint et a/., 2007), submarine fan deposits (Hodgson et a/., 2006; 2009), deltaic deposits and continental slope deposits (Prelat eta/., 2009; Wild et a/., 2009). Fluviodeltaic and paralic conditions dominated the

shallower northern and north eastern parts of the basin (Cadle et a/., 1993).

Deltaic systems originally deposited clastic sediment upon which peat

10 swamps developed in a cool temperate climatic regime (Figure 1.6) (Cadle et a/., 1990, 1993; Cairncross, 2001; Roberts, 1988). This later allowed for the formation of the economically important Permian-aged coal seams mined from the Vryheid Formation today (Cadle et a/., 1990, 1993; lkaneng, 2008}.

Glossopteris flora is abundant in the Vryheid Formation and the flora were the primary contributor of plant material for the formation of the coal

(Falcon, 1986).

s MAIN KAROO BASIN N

KAROO lSUPERGROUP CAPE } Si:iPERGROUP

Figure 1.5- North-south cross-section across the Karoo Basin. See Figure 1.4 for the location of the section (modified after Johnson et at., 1997).

N t

1!!!1 Coal E:J Marsh B Peatswamp D Embayment Ill Towns C1 Predominately sandstone D Predominantly mud rock C!} Tillite 0 50 100 150 200 D Basement I I "" I I Figure 1.6 - A palaeogeographic reconstruction with major depositional environments during the No.4 seam peat accumulations. Rapid deposition and subsidence took place in the east, while in the west peat accumulated in a stable tectonic environment (modified after Cadle et at., 1993).

11 • The Beaufort Group (Cole, 1998) consists predominantly of alternating

sequences of sandstones and mudstones, deposited under continental fluvial

and lacustrine conditions (Smith eta/., 1993; Van Dijk eta/., 1978), during the Late Permian and Triassic periods (Cadle eta/., 1990; McCarthy and Rubidge, 2005). The Beaufort Group strata contain a rich and diverse collection of

fossils. These included both fauna and flora with therapsids (mammal-like

reptiles which were the predecessors to mammals) being particularly

abundant (Johnson et a/., 2006; McCarthy and Rubidge, 2005; Rubidge, 1995). Separate fossil associations correlating with the lithological

subdivisions of the Ecca Group and Beaufort have been used to redefine the Beaufort-Ecca boundary (Rubidge eta/., 2000).

• The (Turner, 1975) consists of alternating layers of

sandstones and mudrocks deposited under fluvial conditions during the Late Triassic period (Cairncross et a/., 1995; Tankard et a/., 1982). Bedload­

dominated river deposits which occurred over large braidplains (Turner,

1980, 1983) later gave way to the meandering river and floodplain deposits

of the in which sporadic coal seams occur (Christie, 1986).

The boundary between the Molteno and Elliot Formation, is marked by

changes in palaeocurrent directions and petrographic characteristics of the units (Bordy eta/., 2005). The Elliot Formation comprises mudrocks and fine­ grained to medium-grained sandstones. A progressive climate change and

aridity during this time is revealed by a change from basal mixed­

load/meandering channel deposits to broader shallow, more ephemeral river deposits and flash flood deposits at the top of the formation (Johnson et a/., 2006). A turnover from temperate to arid climatic conditions is apparent

towards the Early Jurassic as marked by the deposits of the Clarens

Formation. This formation culminates the Karoo sedimentation with fine

grained aeolian sand, playa lake, sheet flood and ephemeral stream deposits

(Eriksson, 1981).

12 • The Group forms the uppermost succession of the Karoo

Supergroup and consists of layers of volcanic flows up to 1400 m thick which

extruded during the middle-Jurassic (Haskins eta/., 1995; Duncan and Marsh, 2006). Today most of this group is eroded away (Figure 1.5) with the

dominant remaining section forming the scenic Drakensberg and Lesotho

Mountains.

1.4.2 The Karoo Igneous Province

The lavas of the Karoo Supergroup form part of the Mesozoic

Karoo Igneous Province and serve as an excellent example of a continental flood basalt province (Walker and Poldervaart, 1949). Tension created during the rifting and subsequent breakup of (Chevallier and Woodford, 1999; Duncan and

Marsh, 2006; Eales et a/., 1984; Watkeys, 2006) resulted in extensive magmatic and volcanic activity and the occurrence of both extrusive and intrusive rocks occurring over large areas of southern Africa (Figure 1.7).

The formal stratigraphic units of the Karoo Igneous Province are shown in Table 1.2.

The main subdivisions of the Karoo Igneous Province are the Drakensberg Group and

Lebombo Group. The two groups geographical separation, coupled with their respective origins and differing compositions make for a convenient basis for their distinction which is summarised by Duncan and Marsh (2006). The basal lavas of the

Karoo Igneous Province are generally considered conformable with the Clarens

Formation; in some areas there is evidence of erosion of the sedimentary rocks to generate significant topographic relief before the onset of the volcanic episodes (Du

Toit, 1954; Duncan and Marsh, 2006). Thereafter, many volcanic eruptions and flows accumulated from successive eruptions to form a pile of mafic and silicic lavas hundreds of meters thick. Some of the best examples include the remnants of the stacked lava flows which form the Drakensberg mountain range along the western

KwaZulu-Natal border, covering most of Lesotho (Duncan and Marsh, 2006) and extending towards the highlands of Lesotho. Here, the once extensive pile of flood basalt lavas was about 1400 m thick (Eales eta/., 1984).

13 :1: Dykeswarm ~ Extensive dolerite intrusions -- Main Karoo Basin Margin

Figure 1.7 - Map of the Karoo Igneous Province of southern Africa (modified after Duncan and Marsh, 2006).

Table 1.2 - The formal stratigraphic units of the Karoo Igneous Province (modified after S.A.C.S, 1980).

KAROO IGNEOUS PROVINCE

Drakensberg Group Lebombo Group (see Figure 1.7)

Formation Rock Type Formation Rock Type

Movene Basalt

Mbuluzi Rhyolite Jozini Rhyodacite Lesotho Basalt Sabie River Basalt

Barkly East Basalt Letaba Picritic basalt

Mashikiri Nephelinite

14 The Karoo Dolerite Suite represents a network of dykes and sills which occur as feeders or tongues to the flood basalt province (Walker and Poldervaart, 1949) and are best developed in the main Karoo Basin (Figure 1. 7). The rocks of the Karoo

Supergroup were pervasively intruded by these dolerite sills and dykes, central ring complexes (Eales et a/., 1984; Galerne et a/., 2008) and saucer-shaped sheets

(Duncan and Marsh, 2006), contemporaneous with and immediately followed the eruption of the Drakensberg lavas, as determined by cross-cutting relations

(Mountain, 1968; Walker and Poldervaart, 1949). Multiple dolerite intrusion events occurred in the Karoo, both predating and postdating the flood basalts (Erlank, 1984;

Mountain, 1968; Walker and Poldervaart, 1949), therefore making it nearly impossible to associate them with any single intrusive or tectonic event (Chevallier

and Woodford, 1999; Duncan and Marsh, 2006; van Zijl, 2006a).

Sills and sheet intrusions in the Karoo range from a few meters to 200 m thick

(Duncan and Marsh, 2006; Walker and Poldervaart, 1949) and often cap hills with underlying sedimentary strata. Some sheet intrusions dip almost vertically and may be termed dykes. The true dykes however, are typically up to 10 m wide and extend

5 - 30k m along strike (Duncan and Marsh, 2006). Generally dykes are unrelated to sills (Eales et a/., 1984) and many dykes appear to have intruded after the sills and sheet intrusions, as revealed by cross-cutting relationships (Walker and Poldervaart,

1949) and resistivity studies (van Zijl, 200Gb). Central ring complexes are often interpreted as sites of original volcanic activity (Eales eta/., 1984).

The approximate trend of the dykes in the central and eastern Karoo is between north and northwest with subordinate trends at roughly right angles (Walker and

Poldervaart, 1949). In the western Karoo, dykes and sills form complex, interconnected and anastamosed systems along with discordant sheets and saucer­ shaped intrusions (Chevallier and Woodford, 1999). In several areas in the Karoo

Basin, the dykes are concentrated in swarms and some have been identified as feeder systems to the overlying lavas (Eales et a/., 1984). However, the majority of the dykes do not show strong preferred orientations (Duncan and Marsh, 2006).

15 The enormous volume of intrusive material and extent of dykes and sheet intrusions as they outcrop today, preserve the actual extent of the original main lava sequences of the Karoo Igneous Province. The areal extent of the dykes and sheet intrusions demonstrates that the lava sequences seen today, are small erosional remnants of a once much thicker and presumably more extensive volcanic blanket (Erlank, 1984), with erosion having subsequently removed vast portions of the ancient flood basalt province. The extent of the eruptions may be inferred due to the occurrence of identical volcanic rocks preserved in post-Karoo aged pipes, as far west as

Jagersfontein in the Northern Cape Province (Duncan and Marsh, 2006; Walker and

Poldervaart, 1949).

The Karoo igneous events were short lived, as is the case with most large flood basalt provinces; 40Ar/9Ar dating by Duncan eta/. (1997) has provided an age of 183 ± 2 Ma using feldspars and whole rocks samples from the Karoo lava flows. These ages obtained by Duncan et a/. (1997are consistent with Rb-Sr isochron ages for similar dolerites in Namibia (Duncan and Marsh, 2006).

It is well known that larger dykes and sills show a characteristic tendency to mobilise and metasomatise surrounding sedimentary strata (Walker and Poldervaart, 1949).

Sediment dykes occurring within dolerite sills in the Beaufort Group are further recognised as evidence for post-depositional sediment remobilisation (Svensen et a/., 2010). These sediment dykes comprise metamorphic sandstone implying that they intruded the sills while they were still hot (op. cit).

The intrusion of sills in the Karoo also more commonly lead to the formation of diatremes, or otherwise known as hydrothermal vents (Svensen et a/., 2006, 2007). Diatremes are regarded as funnel or carrot shaped pipe-like structures with steep walls, which penetrate vertically through the surrounding strata and taper at depth

(White and Ross, 2011). They are filled with breccia which includes strongly lithified sediments and clasts derived from the surrounding strata (Duncan and Marsh, 2006;

Rakovan, 2006). They are formed by a subterranean gaseous explosion and are generally 20 - 150 m in diameter (Duncan and Marsh, 2006; Lorenz and Kurszlaukis,

2007; Svensen et a/., 2006, 2007). They are thought to be the result of phreatic or

16 phreatomagmatic activity (Coetzee, 1966; Gevers, 1928; Svensen eta/., 2006, 2007).

The resulting diatremes are usually small (tens to hundreds of meters in diameter) but the explosions which formed them were quite violent.

Diatremes are a common occurrence in the Karoo basin (Figure 1.8) with over 320 diatremes having been identified. They comprise a range of different rock types, ranging from lava and pyroclastics to sediment breccia and sandstone (Dingle et a/.,

1983; Du Toit, 1926, 1954; Roux, 1970; Svensen et a/., 2006). Diatremes are known to be associated with the sill emplacement (Lorenz and Kurszlaukis, 2007; Jamtveit et a/., 2004; Svensen et a/., 2006); evidence to support this includes thin lenses of fluviatile sandstone interbedded with the lowermost lavas and by the occurrence of pillow lavas and associated hyaloclastite breccias (Duncan and Marsh, 2006). The diatremes, such as those in the Eastern Cape and Lesotho (Duncan and Marsh, 2006;

Svensen et a/., 2006), generally consist of strongly lithified sandstone breccias

(Svensen et a/., 2007). Although most diatremes outcrop on the surface as cone shaped depressions, similar to volcanic craters, typical Karoo diatremes show positive relief on the land surface due to their higher erosional resistance (ap.cit. ).

NA

&~ ~0 ~""(' ~ 400km

Karoo Flood Basalts/ e Breccia Pipes D Sediments • Lembobo Volcanics e Diatremes 18°E 2tE 26°E 28°E Figure 1.8 - The distribution of known diatremes and "breccia pipes" in the Karoo Basin, South Africa. Diatremes are mainly confined to the Molteno, Elliot and Clarens Formations. Breccia pipes refer to sediment dominated cylindrical pipes confined to the Ecca and Beaufort Groups as described by Woodford et a/. (2001) (modified after Svensen et a/., 2006).

17 1.5 Past Studies

There exists a large collection of works pertaining to the evolution and characterisation of the Karoo Basin deposits. Some of the earliest describe the Karoo

Basin from a stratigraphic point of view and were less focused on the interpretation of depositional environments. The term 'Karoo System' (Du Toit, 1926) was used then to include all the strata from the base of the 'Dwyka Conglomerate Series' to the 'Stormberg Series'. The volcanic beds of the modern Drakensberg Group were considered to fall within the 'Stormberg Series'.

Hatch and Corstorphine (1909) described the Karoo Basin deposits during a time when there were considerable differences of opinion as to the best groupings and subdivisions of the system (op. cit). Schwarz (1925) applied a purely descriptive approach to the geology of the 'Karoo Formation'. The Dwyka Conglomerate was correctly identified by Schwarz (1925) as having a glacial origin. However, the terms

diamictite and tillite are omitted from his descriptions; Du Toit {1926) stated that the term "conglomerate" was unsatisfactory and thereafter the term tillite was

preferred by most authors, including Rogers eta/. (1929), who describes the units in

intricate detail. More evidence of the glacial origin of the Dwyka rocks accumulated and the inferred movements of the ice sheets was interpreted from glacial striations

present in the rocks (Du Toit, 1954).

In the 1950's, Du Toit (1954) proposed the lithostratigraphic subdivisions of the

Karoo System into the Dwyka, Ecca, Beaufort and Stormberg Series. The subdivisions of each of these Series were straightforward for the most part, employing the terms upper, middle and lower to differentiate between units. The modern formal subdivisions are prescribed by S.A.C.S (1980) (Table 1.1) after detailed study and compilation of many works relating to the Karoo Basin deposits. The term

'' has been discontinued though is still used informally, and the component units are at the formation level only.

Hobday (1978) constructed an interpretation of the infill sequence of the eastern

Karoo Basin based on observation and analysis of the fluvial deposits of the Ecca and

Beaufort Groups and noted the contrast in tectono-sedimentary terrains with

18 marked differences in the style of fluvial sedimentation. Tankard et a/. (1982) reviewed the depositional history of the Karoo Supergroup, describing the sequences as a record of the changing tectonic framework and migration of Gondwana, from polar to tropic latitudes during the late Carboniferous to Jurassic, which thus accounts for the board spectrum of palaeoenvironments interpreted from the sequences.

The Ecca Group and the occurrence of the economically viable coal deposits were well known from the 1930's onwards due to work of du Toit (1926) and Wybergh

(1925). Du Toit (1954) describes the origin of the coal seams and notes the differences between them. Smith and Whittaker (1986) investigated the distribution of the coal seams in the Vryheid Formation, concluding that the lower seam peat accumulation was controlled by pre-Karoo palaeohighs and associated glacial valleys, whereas the upper seams were primarily controlled by the progradation of fluvio­ deltaic systems. It became understood that the palaeolandsurface formed by the

Dwyka Group rocks is fundamental in understanding the distribution and thickness of the coal seams in the overlying Vryheid Formation, particularly in the coalfields located close to the northern basin margin. Cairncross (1986) found that there is a correlation between the nature of the basin topography, depositional systems, coal seam distribution and coal seam quality in the Vryheid Formation, with palaeotopography exercising direct control on sedimentation patterns and peat formation (Cairncross 1986, 1990). The study provides a comprehensive framework for coal-seam stratigraphy, occurrence and distribution, based in the Witbank coalfield, whilst a similar study for the Highveld Coalfield was presented by Cadle

(1995).

South African coals accumulated under relatively low ambient temperatures relative to those in the northern hemisphere, resulting in slower oxidation of accumulated mineral matter. The coals therefore have low friability due to a smaller concentration of available pore space. Sanderson (1997) showed that despite these factors, there is still exploitable coalbed methane potential in some areas of the coalfields.

19 The volcanic beds of the modern Drakensberg Group which cap all of the above mentioned strata were considered to fall within the 'Stormberg Series'. Some of the most pioneering work regarding the volcanic episode was produced by Du Toit

(1926). He describes the volcanic beds and flows with reference to their thickness, areal extent, general appearance and relationship to underlying strata. Du Toit

(1926) also notes that the Karoo endured both intensive and extensive intrusions by dolerite sills and dykes. The area of sub-outcrop of the Karoo volcanic events is much greater than that of the sub-aerial exposure (Eales et a/., 1984). This has lead to many workers presenting estimates and evidence for its original extent (op. cit).

Walker and Poldervaart (1949) focused primarily on the Karoo dolerite intrusions which represent the intrusive phase of the Karoo Igneous activity. Besides providing detailed descriptions and petrographical investigations, they also produced relevant discussions into the mechanisms of intrusion of the dolerites. The age of the rocks of the Karoo Igneous Province has been a topic of debate with a very large number of radiometric age determinations having been carried out and made available over the years. Erlank (1984) covers this topic in great detail along with the general petrogenesis of the volcanic rocks of the Karoo.

Diatremes in the Karoo were recognised early on by Du Toit (1926) as 'Stormberg

Volcanoes' and noted to occur in a 'most irregular manner, usua/Jy in little groups'

(op. cit). General descriptions of some diatremes were provided for those in the

Griqualand-east area (Du Toit, 1929) with later publications including their common occurrence and distribution over southern Africa (Du Toit, 1954). They have also been described as volcanic vents (Gevers, 1928) filled with agglomerate containing fragments of lavas and sedimentary rocks. The mechanism of formation and emplacement of these breccia filled pipes was investigated by King (1963). Roux

(1970) studied eight diatremes of Stormberg Group (Late Triassic) in detail in the eastern Free State near Lesotho and provides some insight into the mechanism of their formation. Recent work on the diatremes (Jamtveit et a/., 2004; Svensen et a/.,

2006; White and Ross, 2011) indicates that their formation is related to dolerite sill emplacement.

20 Summaries on Karoo igneous activities within a generalised regional context are provided by Du Toit (1956), Mountain (1968}, Truswell (1977) and Tankard et a/.,

(1982). Erlank (1984) explored in great detail the petrogenesis and petrographical characteristics of the Karoo volcanic rocks. This work constitutes the most detailed examinations of the Karoo Igneous Rocks, whereas the most up-to-date review is given by Duncan and Marsh (2006), which also incorporates the formal modern nomenclature and stratigraphic units of the Karoo Igneous Province.

21 CHAPTER2

STRATIGRAPHY

2.1 Stratigraphy of the Vryheid Formation and the Highveld Coalfield

In order to understand the unusual occurrence of the brecciated cores, the stratigraphy of the Highveld Coalfield needs to be examined. The lithostratigraphy for the Karoo basin showing the position of the Vryheid Formation is shown in

Table 1.1 as defined by the South African Committee for Stratigraphy (S.A.C.S.,

1980).

The Vryheid Formation in the Highveld Coalfield comprises alternating sequences of minor conglomerates, sandstones and shales (Cadle et a/., 1990). It is a vertically stacked package of upward-coarsening cycles which represent lobate deltaic deposits combined with upward-fining facies assemblages that are of bedload fluvial origin (Cairncross, 1989, 2001; Cairncross and Cadle, 1988a, 1988b; Hobday, 1978).

The peats of the Vryheid Formation accumulated within swamps in a cool temperate climatic regime and were associated with delta plain, back barrier and fluvial environments (Cadle et a/., 1990). The entire package rests conformably on the tillite, glaciofluvial and glaciolacustrine deposits of the Dwyka Group or on the pre­

Karoo rocks in the north, whilst pinching out against numerous local basement highs, particularly in the Witbank coalfield, due to the uneven pre-Karoo topography

(Cairncross, 1989; Galloway and Hobday, 1996; Johnson et a/., 1997). It is wedge­ shaped (Figure 2.1), thickest in the south and southwest and thins towards the north and northeast (Johnson et a/., 1997). The Pietermaritzburg Shale Formation, which separates the Dwyka Group and Vryheid Formation, is absent along the extreme northern Karoo Basin margins (Cairncross, 1998).

The Witbank and Highveld Coalfields show a similar stratigraphy with up to six coal seams. In the both coalfields, the palaeotopography exercised direct control on the peat accumulation, particularly the lowermost seams, with variations in coal-seam thicknesses being influenced in places by differential compaction (Cairncross, 1989).

22 North Newcastle South

:~m ~~·-"'~'"==.....,._.._ km 0 25 50 75100

c:J Fluvio-deltaic sediments L:::::J Fluvial sediments [:J Shelf sediments I; .. ;j Diamictite (DwykaGroup) l!tt!l Basement

Figure 2.1- Schematic north- south section through the north-eastern part of the Ecca Group (modified after Johnson et at., 1997)

The Witbank coal seam nomenclature also applies to the Highveld Coalfield. Thus seams in the Highveld Coalfield are numbered from No. 1 at the base to No.5 at the top. They are associated with the arenaceous and argillaceous facies with sandstone

and minor conglomerate (Cairncross, 1989). Partings between the seams are variable from less than 1 m between the No. 3 and No. 4 seams, to tens of meters between the No. 4 and No. 5 seams. Figure 2.2 shows some typical stratigraphic columns in the Highveld Coalfield.

The No. 1, 2, and 3 seams are generally poorly developed, thin or absent over most of the Highveld Coalfield, especially in the southern and eastern parts (Cadle et at., 1990; Jordaan, 1986; Snyman, 1998). The No. 4 seam is economically the most important in the Highveld Coalfield. It is laterally continuous with an average thickness of approximately 4 m. It consists of a dull coal with shale lamina near the top. The No. 5 Seam is only economically mineable in the northern and western parts of the Highveld Coalfield. It is thin (0.5 - 1.5 m thick) and consists mainly of bright, high quality coal, but often bears shale partings, which makes it more undesirable to mine. Present day erosion has removed the No.5 seam in most areas.

23 LEAN ORA KRIEL VAL BOSJESSPRUIT NEWOENMARK AREA AREA AREA AREA AREA metres 0

50

100

150

200

So .• , mill'' 250 1>>1 Dolerite D Shale and siltstone ~ Coal with seam number ~ ~hale and sandstone ~~ Owyka tillite ~ Interbedded l

Figure 2.2- Typical and simplified stratigraphic columns in the Highveld coalfield {modified after Snyman, 1998).

2.2 Genetic stratigraphy of the Highveld Coalfield

Some problems arise from using coal seams as stratigraphic markers due to the number of pinch-outs against valley margins and seam splits encountered in the coal seams. For this study, a method as first defined by Busch (1971), termed genetic lithostratigraphy, is preferred due to that fact that this method allows for lateral correlation of facies whether the seams are present or absent. The limitations in applying lithostratigraphic nomenclature to the Vryheid Formation were highlighted by Cadle (1974). Le Blanc Smith (1980) also noticed its shortcomings and proposed a genetic stratigraphic classification for the Witbank Coalfield.

24 Cadle (1982) proposed that the sedimentary successions of the Witbank and

Highveld Coalfields may be informally divided into progradational and aggradational depositional sequences, each of which terminates at a coal seam or stratigraphically comparable horizon due to their laterally continuity. Cadle (1982) and Winter (1985) implemented this system and divided the sedimentary successions of the north­ western and northern Highveld Coalfields respectively, grouping them into the No. 2 seam, No. 4 seam, No. 5 seam and No. 6 seam sequences. Cairncross (1986) and

Cairncross and Cadle (1988a, 1988b) adopted a similar scheme using the informal terms No. 2, No. 4 and No. 5 seam sequences to divide the sedimentary successions of the east Witbank Coalfield.

For this study, the genetic stratigraphy of the Highveld Coalfield is based on depositional sedimentary sequences as defined by Cadle (1974; 1995). Every depositional sequence is delineated based on the sedimentological interpretation of borehole logs and cross-sections with each genetic sequence being named after a main coal seam. The Vryheid Formation is subdivided as shown in Table 2.1. Detailed information regarding the scheme and each genetic package in the Highveld

Coalfield sequence is provided by Cadle (1995). The lithologies and genetic depositional sequences of the Highveld Coalfields are presented as a composite stratigraphic profile shown in Figure 2.3.

Table 2.1- An informal genetic stratigraphy for the Highveld Coalfield (Winter, 1985).

LITHOSTATIG RAPHY GENETIC STRATIGRAPHY

No.6 Seam Genetic Sequence

No.5 Seam Genetic Sequence Vryheid Formation No.4 Seam Genetic Sequence

No.2 Seam Genetic Sequence

Dwyka Group

25 GRAIN SIZE INCREASE

GRAVEL COARSE SANDSTONE FINE SANDSTONE SILTSTONE I MUDSTONE I SEAM GENETIC No. SEQUENCES 6

6 SEAM PRIMARY SEDIMENTARY STRUCTURES GENETIC SEQUENCE ' CROSS-BEDDING CROSS-lAMINATION -,... FlASER-LAMINATION 5 = INTERLAMINATION C> LENTICULAR-LAMINATION

u. BIOTURBATION 5 SEAM GENETIC GLAUCONITE SEQUENCE *

4 SEAM GENETIC LITHOLOGIES SEQUENCE II COAL INTERLAMINATED CLAYSTONE-SILTSTONE 2 II mE SILTSTONE ~ 2L INTERLAMINATED ~ SANDSTONE-SILTSTONE Local lEd SANDSTONE 2 SEAM GRAVEL GENETIC II Local SEQUENCE ~ DIAMICTITE rn BASEMENT

Figure 2.3 - A typical composite stratigraphic column for the Highveld Coalfield (modified after Winter, 1985).

26 2.3 Stratigraphy of the study area

The stratigraphy of the study area shows little deviation from that of the Highveld

Coalfield's general stratigraphy. A typical stratigraphic column for the study area is

shown in Figure 2.4. The No. 4 seam, which is the most economically important

seam, lies at an average depth of 160 - 200 m below surface and has an average

thickness of 2 - 3 m and is often overlain by arkosic, trough cross-bedded

sandstone/granulestone or a carbonaceous cross-bedded and interlaminated

sandstone/siltstone. It is occasionally split by seam partings composed of

interlaminated sandstone and siltstone. The No. 3 seam is not laterally continuous

throughout the study area, but when it is present, it is vitrinite-rich, reaching a

maximum thickness of approximately 0.6 m. The No. 3 and No.4 seams are generally

separated by 3 - 4 m of cross-bedded sandstone and carbonaceous siltstone. All

other seams are poorly developed or absent. The No. 3 and No. 4 seams are

occasionally thin, poorly developed or absent.

Thinning, absence or poor development of the upper coal seams of the coal seams is

likely due to the interference of underlying palaeohighs, inferred from the fact that

the palaeotopography exercised direct control on the peat accumulation (Cairncross,

1979, 1989) (Figure 2.5). The rest of the sequence comprises sandstones, siltstones,

and shales. Stanimirovic (2002) describes each lithofacies from the basal Dwyka

Group tillites to the argillaceous units of the Volsksrust Formation, overlying the

Vryheid Formation in detail.

Two to three dolerite sills are present in the upper parts of the sequence

(Figure 2 4). The overlying sill is medium to coarsely crystalline and non-porphyritic,

whereas the lower sills are more porphyritic. They are often separated by

approximately 10 m of shale, siltstone or sandstone. However, there are some areas

where there is little or no separation between them, resulting in one composite sill

reaching a thickness of up to 90 m. Dolerite stringers and smaller sills are common throughout the sequences, particularly in the lower sections, within 30 m of the

underlying tillite or basement granite.

27 SOIL: Derived from weathered dolerite and siltstone/sandstone.

SllTSTONE/SANDSTONE/SHALE: CoarseninB"Upwards into medium-grained sandstone.

DOLERITE: Highly jointed, medium to coarsely crystalline. Non-porphyritic with fractures. Frequently occurs as a composite sill with internal chill margins, attaining a thickness 90m.

SllTSTONE/SANDSTONE/SHALE: Coarsening-upwards to medium sandstone.

DOLERITE: Medium to coarsely crystalline, porphyritic sill.

SANDSTONE/SILTSTONE: Horizontal and waw interlaminations of fine-to medium-grained sandstone and micaceous siltstone.

SILTSTONE: Bioturbated siltstone with minor sandstone laminations.

SANDSTONE: Poorly sorted, fine-to medium-grained, silt throughout. SANDSTONE/SllTSTONE: lnterlamlnated apd Interbedded fine-grained sandstone and siltstone. SANDSTONE: Poorly sorted. micaceous, fine-to medium-grained with poorly developed upward-fining sets. ~ ... SILTSTONE/SANDSTONE·Interlamlnated siltstone/shale and minor sandstone • t;:; :::E 160 SANDSTONE: Sparsely micaceous with upward-fining sets and medium-grained bases. ~ SANDSTONE/SILTSTONE· Wavv and horizontally lnterlaminated. "' ~~~~~r~~2~~conitlc and medium-grained. ..."'z u 140 SILTV SANDSTONE/SANDSTONE: lnterlaminated and interbanded, upward­ "':f fining trough cross-bedded sets; overall coarsening.Ypward. 1- SANDY SILTSTONE/MUDSTONE: Overall upward-coarsening with thin interlaminations of stacked, small scale (

120 SANDSTONE: Medium-grained and glauconitic at top. Marker. COAL No. 4A SEAM:_~poradlcally deveio~d. SANDSTONE/SilTV SANDSTONE: lnterlamlnated.

SANDSTONE6 Arkosic, tr~h cross-bedded,occasionally garnetlferous. GRANULEST NE: ~~\~:~~wo~~~~~~~-~=~:~e~~~~sJ~t:J:.1<0.5m). ~A>~o~o1.i~~~lt'rsTONE: Fin~rained m~aceous sandstone with minor silt COAL No.3 ~EAM. lam1nae.0.2m s1lty sandstone layer at top.

SANDSTONE: Silty, fine-grained, locally bioturbated.

SILTSTONE/SHALE: locally carbonaceous with occasional fine-grained sandstone bands.

COAL: No. 2 seam SANDSTONE: Fine-grained.

Legend: SANDSTONE: Dwykatillite White, medium-to coarse-grained. .rJ Overburden - Granite Basement

Breccia SANDSTONE/SILTSTONE: il ::~::::e • Flne-Rrained sandstone ~ Alternating sandstone ~.·. Altered lithologies interlamlnated with siltstone. ~ andsiltstone ~ Dolerite -Mudstone/shale - DOLERITE: Dolerite stringer. Coal TILLITE or GRANITIC BASEMENT -

Figure 2.4- A typical stratigraphic column for the study area based on borehole core logs as well as columns modified after Stanimirovic (2002) and Winter (1985).

28 X X X X X

EXPLANATION x Control point f: · :;I Sandstone ~ Pre-Karoo Basement -Coal ~ Granulestone 20L E:::l Siltstone ~ Diamictite ~ ~ 10 Q) E o 0 500 1000 meters

Figure 2.5 -The effect of pre-Karoo basement paleotopographic highs. Note (a) the shale-out of lower seam coal over the basement ridge, (b) the thicker coal in the adjacent palaeovalley, and (c) the thinning of the sequence and upper seam due to differential compaction above the basement high (modified after Cairncross, 1989).

The stratigraphy of the study areas surrounding the boreholes was mapped in detail with the use of data obtained from borehole logs; 110 boreholes core logs were selected and analysed to produce a series of maps, cross-sections and fence diagrams. For this task, a total of 55 borehole core logs were selected along with the

3 brecciated borehole core logs to cover a maximum area of 35 km 2 around brecciated sequences A and C combined, and approximately 45 km 2 around brecciated sequence B.

In all of the cross-sections and fence diagrams which follow throughout the rest of this chapter (Figures 2.8-2.9; 2.11-2.13; 2.15-2.17), the boreholes surrounding each of the brecciated borehole core sequences, show completely normal Vryheid

Formation stratigraphy throughout their entire sequences; even the closest boreholes remain completely undisturbed. The brecciated sequences show little to no correlation with the surrounding lithologies. The deformational event/s which produced the brecciated sequences are therefore interpreted be have been highly

29 localised. It is also noted that due to the uncertainty pertaining to the lateral extent

of the brecciated sequences, the depiction of the zone of brecciation surrounding

each brecciated borehole core sequences is inferred from the proximity of the

closest undisturbed borehole core sequences relative to brecciated sequences in

each of the afore mentioned figures. The depth at which brecciation begins in each

of the brecciated sequences was determined from relative the borehole core logs.

The depth to which the brecciation extends is unknown. The core from the

brecciated sequences recovered extends between 170 m depth for Core A, to 240 m

depth for Core B, with Core C extending to 230 m. Thus it may be inferred that the

brecciated sequences extend to at least 240m depth below surface.

The locations of the cross-sections and fence diagrams relative to and intersecting

the brecciated core sequence A (Core A) are given in Figures 2.6. The cross-sections

are shown in Figure 2.7 and Figure 2.8 and the fence diagram is shown in Figure 2.9.

The borehole located nearest to Core A, lies within 250 m.

N AI t

:········································~:iiii

I''·············~:

iP.{I~ ...... :

0 0.5 1.5 2 kilometers

Figure 2.6 - The locations of the cross-sections through brecciated core sequence A. The inset shows the location of the fence diagram through the sequence.

30 II

legend - IJ Overburden 50 - ',i :.::· 40 Alternating sand.stone ~ and siltstone C1.l 30 Mudstone/shal~ ~ Dwyke Tillite E 20 Breccia

10 Alt~redlitholosoes I 1Ill Dolerite 0 0.5 1 -Coal kilometers • 1' I -I w ...... Figure 2.7- North-south cross section through brecciated core sequence A. "1- -1" =inferred lateral extent (see text). See Figure 2.6 for location. AIV

50 ., 40 .... QJ ..... 30 Legend QJ E 20 IJllOverburden I Dwyka Tillite ~il_Sandstone Breccia 101 IJI Siltstone fll Altered lithologies ? Alternating sandstone • Dolerite 0 1 2 and siltstone Mudstone/shale - Coal kilometers I w N Figure 2.8- Southwest-northeast cross section through brecciated core sequence A. "1+-- ->I"= inferred lateral extent (see text). See Figure 2.6 for location. Legend £ Overburden Dwyka Tillite ;:-> I N ~.: 'l Sandstone Breccia II Siltstone ·. Altered lithologies es BrcJ Atter':'atins sandstone • Dolerite liiJ and s1!Utone t • Mudstone/shale - Coal

so 40 Ill 30 ~ G) 20 E 10 0

0 250 meters

Figure 2.9- Fence diagram through brecciated core sequence A. The horizontal scale refers to distance between boreholes, whereas the vertical scale refers to core depth. "1<-- -+1" = inferred lateral extent (see text). See Figure 2.6 for location.

33 Figure 2.10 shows the locations of the cross-sections and fence diagrams relative to and intersecting brecciated core sequence B. The closest borehole to brecciated sequence C lies within 500 m. The cross-sections are shown in Figure 2.11 and Figure

2.12 and the fence diagram is shown in Figure 2.13.

Nt

0 1 2 3 4 kilometers

Figure 2.10- The locations of the cross-sections and fence diagram through brecciated core sequence B.

34 CORE B -~-

>, ~-~----~--

:'.~~,~,,

"~., ...... BII

Alternating sandstone 50 and siltstone Mudstone/shale 40 ~ ~ Q) 30 ~ E 20 _,... Altered lithologies 10

0 0.5 1 1.5 2 ? kilometers w V1 Figure 2.11- Northwest-southeast cross section through brecciated core sequence B. "1+- _, .. =inferred lateral extent (see text}. See Figure 2.10 for location. sn1

50 40 .... "'Q) ...... 30 Q) E 20 Legend 10 Qyerburden ~~~~7~!;~~!andstoneBreccia IJ 1 F~~~ I I . I c.; Sandstone Mudstone/shale ., ~::1Altered lithologies 0 0.5 1 1.5 2 r. Siltstone • Owyka Tillite • Dolerite Coal kilometers - w 0'\ Figure 2.12- Southwest-northeast cross section through brecciated core sequence B. "1- -+I"= inferred lateral extent (see text). See Figure 2.10 for location. N Legend IJ Overburden I Dwyka Tillite ~\] _ ] Sandstone Breccia a Siltstone il:j Altered lithologies Alternating sandstone • Dolerite t IJ and siltstone • Mudstone/shale - Coal

40 ~ 30 ~ 20 ~ 10 0

0 1 2 kilometers

Figure 2.13 - Fence diagram through brecciated core sequence B. The vertical scale refers to core depth; the horizontal scale refers to the distance between boreholes. "1+- -+I" = inferred lateral extent (see text). See Figure 2.10 for location.

37 The locations of the cross-sections and fence diagrams relative to and intersecting brecciated core sequence C are shown in Figure 2.14. Cross sections are shown in

Figure 2.15 and Figure 2.16.The fence diagram is shown in Figure 2.17. It is noted that the borehole located closest to brecciated sequence C lies within 250 m.

c'

c'

~------c"·

.. ··· .. ··

en

0 5 1 5 kilometers

Figure 2.14 - The locations of the cross-sections through brecciated core sequence C. The inset shows the location of the fence diagram through the sequence.

The most prominent difference noted between the surrounding sequences and the brecciated sequences is the absence of the No. 4 coal seam (as well as any other potential subordinate seams). Instead, the coal occurs as clasts scattered throughout the brecciated sequences. All the breccia clasts are locally derived intraclasts from the surrounding Vryheid Formation and include dolerite breccia clasts.

Core A and B are capped by thick, relatively unaltered dolerite similar to the dolerite in the surrounding boreholes. Core C (Figure 2.15- 2.17) has no dolerite present near surface, although the absence of dolerite in two cores located west of the brecciated sequence suggests that it has been removed by weathering.

38 en

Legend 'IJ Overburden so '·'.:.~=· 40 Alternetinc sandstone 1:! anchiltstone Cll J Mudstone/~hate ..... 30 Cll OWVkaTUiitto E 20 Br.c:cla 10 IAltered litholocl~ I Ill Dolerite 0 0.5 -Coal kilometers ? • w 1.0 Figure 2.15- North-south cross section through brecciated core sequence C. "r<- ---+r" =inferred lateral extent (see text). See Figure 2.14 for location. 50 40 ~ Legend QJ 30 l"!j Overbunlen Dwvt

0""" Figure 2.16- West-east cross section through brecciated core sequence C. "1<- -+I"= inferred lateral extent (see text). See Figure 2.14 for location. Legend N ~ Overburden I Dwyka Tilltte j j ' Sandstone Breccta Siltstone ,.__ Altered lithologies Alternating sandstone • Dolerite and siltstone t I Mudstone/shale - Coal

so 40 ~ 30 ~ 20 ~ 10 0

0 250 meters

Figure 2.17- Fence diagram through brecciated core sequence C. The vertical scale refers to core depth; the horizontal scale refers to the distance between boreholes .. "1+- ->1" = inferred lateral extent (see text). See Figure 2.14 for location.

41 CHAPTER 3

PETROLOGY, PETROGRAPHY AND MINERAL CHEMISTRY

3.1 The undeformed lithofacies in the study area

Knowledge of the normal facies present in the study area is needed in order to understand the nature of the brecciated core sequences. The most widely accepted definition of a facies was proposed by Moore (1949): "A sedimentary facies is defined as any aerially restricted part of a designated stratigraphic unit which exhibits characteristics significantly different from those of other parts of the unit".

A detailed facies investigation in the study area was conducted by Stanimirovic (2002).

This work provides the basis for the descriptions of the representative facies present in the study area. All of the rock types encountered in the study area, including those present as clasts within the brecciated core sequences, are described in this chapter and correlated to the relevant facies assemblages of Stanimirovic (2002), which are defined and distinguished from one another based on the following criteria:

• lithology

• grain size (see Table 3.1)

• grain roundness and sphericity (see Figure 3.1)

• presence or absence of sedimentary structures

• presence or absence of biogenic structures

• any other stratigraphically distinctive minerals present

Five main facies have been identified in the study area, with each containing a number of sub-facies. Each facies and sub-facies has been named, described and interpreted by

Stanimirovic (2002). The interpretation of any one facies is dependent on its location within the stratigraphic sequence. The main facies types which are described are:

42 Table 3.1- The Udden-Wentworth grain size scale, used for classification of grain size of sedimentary rocks throughout this study (modified after Nichols, 2009).

Udden-Wentworth grain-size scale mm phi ((J)) Name (above 256) Boulders Gravel 256 -8 Cobbles 128 -7 64 -6 32 -5 16 -4 8 -3 Pebbles 4 -2 2 -1 Granules Sand 1 0 Very coarse sand 0.5 1 Coarse sand 0.25 2 Medium sand 0.125 3 Fine sand 0.063 4 Very fine sand 0.031 5 Coarse silt Mud

0.0156 6 Medium silt 0.0078 7 Fine silt 0.0039 8 Very fine silt (below 0.0039) Clay

Figure 3.1- Roundness and sphericity scale (modified after Powers, 1953).

43 1. Conglomerate Facies

These are coarse-grained lithofacies of both ortho-conglomerates and para­

conglomerates found in the study area with three recognised conglomerate sub­

facies, subdivided by the presence or absence of sedimentary structures.

2. Sandstone Facies

This facies contains all sandstones composed of clastic grains with sizes ranging

from 0.0625 mm to 2 mm (Table 3.1) and contains seven sub-facies.

3. lnterlaminated sandstone-siltstone facies

This facies includes a range of lithologies from siltstone to fine-grained

sandstone with three recognised sub-facies. The boundaries between the sub­

facies are gradational and are dependent on the amount of siltstone and

sandstone present.

4. Siltstone facies

The siltstone facies contains siltstones composed silt sized particles (Table 3.1).

Although clay sized grains may be present in these, the percentages are usually

very low. Occasionally the term 'mudstone' is used to describe those clastic

sedimentary rocks, with grain sizes less than 0.031 mm. These rocks comprise a

relatively small percentage of the lithologies present in the Highveld Coalfield.

The siltstone is characteristically massive and/or bioturbated and is interbedded

with sandstone.

5. Coal facies

The coal facies comprises the laterally continuous ~2 m - thick No. 4 seam. The

No. 2, No. 3, No.4, No.4 A and No. 5 seams may also be present. The coal facies

is usually present as humic, high-to medium-volatile bituminous coal composed

of alternating dull, lustrous and bright coal bands.

44 An undeformed borehole core sequence from the study area was logged and sampled.

Stanimirovic (2002) defined the facies and sub-facies from an area adjacent to the present study area. The samples from the undeformed borehole core sequence were compared and correlated to these known facies and sub-facies types and refinements to the scheme (op.cit.) where made. The facies and sub-facies found in the present study area are summarised in Table 3.2. Furthermore, each sub-facies was assigned a unique sub-facies code which is indicated in the table and used throughout this study. Examples of the facies standards from the undeformed borehole core sequence are illustrated in

Figure 3.2.

In addition to the sedimentary lithofacies, codes were also allocated to the igneous rock-types present. Dolerite dykes and sills are pervasive throughout the study area.

These are generally unaltered, but in the case of the brecciated core sequences described in this study, altered dolerite is encountered. Both have been assigned the code 'dol'. Dark green sulphide-rich concretions are also occasionally present in the successions. They are composed of angular quartz grains, microcline and micas which are all enclosed in matrix of sulphides. They have been assigned the code 'sc'.

45 Table 3.2- Facies and sub-facies found in the study area (modified from Stanimirovic, 2002, with additions based on own observations}.

Facies Sub-facies Code Description Interpretation Conglomerate Diamictite d Poorly- or non-sorted with a wide Gravity driven debris range of clast types (Dwyka Group flows, slumps and Diamictite). glacial fill deposits

Massive me Type 1 -Well-sorted, clast-supported Type 1 -glacio-fluvial conglomerate conglomerate with well-rounded, processes. highly spherical clasts. Type 2 - Matrix-supported poorly Type 2 -gravity flow sorted, small-pebble conglomerate. processes, such as Roundness and sphericity varies. debris flows.

Cross -bedded cbc Light-grey to white in colour with Produced by small-pebble angular to sub-rounded migrating sand waves conglomerate quartz pebbles in a silty or sandy under different matrix. May incorporate coal-spar and fluvial flow siltstone rip-up clasts. regime conditions.

Sandstone Massive ms Well-sorted with grains that are fine Formed by rapid sandstone to very coarse. Colours vary between deposition from white and light-grey, green and suspension under brown. Interbedded with siltstone, fluvio-deltaic or cross-bedded and wave-ripple cross- marine conditions. laminated sandstone.

Planar cross- pes Fine to very coarse grained, Produced by the bedded planar cross-bedded, grey-white downstream sandstone arkosic sandstone, with minor migration of two- amounts of silt and mica. dimensional sand dunes under fluvial conditions.

Trough cross- tcs Grey-white, fine to coarse-grained, Produced by the bedded trough cross-bedded sandstone with downstream sandstone a high silt and mica component. migration of three- dimensional sand dunes under fluvio- deltaic conditions

Planar pis Light-grey, medium- to very fine- Deposition of laminated grained sandstone containing minor sediment in sandstone silt, mica and heavy minerals, with horizontal layers at parallel to sub-parallel lamina. high flow velocities under fluvial conditions.

46 Table 3.2 -Continued ... Facies Sub-facies Code Description Interpretation Cross- cis Cross-laminated, fine- to medium- Interference of laminated grained, grey-white sandstone with waves and currents sandstone minor siltstone and mica present. produces cross Sandstone lamination under (continued) fluvio-deltaic or marine conditions. Glauconite gs Grey, green-flecked, well-sorted, fine- Formed during sandstone to medium-grained sandstone with shallow marine granular green glauconite grains. transgressive Associated with cross-laminated episodes. sandstone and marine bioturbation.

Bioturbated bs Grey sandstone ranging from fine- to Deposited during sandstone coarse-grained, containing significant episodes with high percentages of silt. Bioturbation rates of deposition occurs mainly as vertical burrows. where organisms had to burrow vertically to keep pace with the rapidly depositing sediment.

I nterlaminated Flaser- fls Fine- to medium-grained, grey Flaser lamination sandstone- laminated sandstone with wisps of dark-grey forms by deposition siltstone sandstone siltstone scattered throughout in of sand and silt discontinuous drapes a few during episodic millimetres thick and less than a few events of bedload centimetres long. traction and suspension settling, respectively.

Wavy- wss Fine- to medium-grained white-grey Forms as a result of laminated sandstone characterized by wavy alternating episodes sandstone- bedding surfaces that separate of suspension siltstone individual sets. The lamina vary settling and bedload in thickness between a few deposition of sand. millimetres to 5 em. Dark-grey, highly carbonaceous and micaceous siltstone sandstone lamina are also commonly found at more or less regularly spaced intervals of about 5 to 10 em. They vary in thickness between 2 mm - 3 em on average.

Lenticular- lis Consists of dark-grey carbonaceous Forms as a result of laminated siltstone with thin, interbedded suspension settling, siltstone sandstone lenses up to 3 em thick, coupled with current separated by very sharp contacts. flow that generates Lenses vary from 10 mm to 20 em in the starved, sandy length. ripples.

47 Table 3.2- Continued ...

Facies Sub-facies Code Description Interpretation Siltstone Gravelly grs Comprises grey to dark-grey Fine gravel occurs as siltstone carbonaceous siltstone, with debris rain which significant sand and gravel content. falls onto the silty Coarse grains are poorly sorted, and basin floor when may be horizontally laminated released by floating throughout the siltstone matrix. ice. It is usually confined to the lower stratigraphic units Glauconite gsi Normally occurs as a massive dark- The presence of siltstone grey to grey-brown siltstone, but may glauconite most contain laminated sandstone commonly suggests interbeds and lenticular lamination. marine settings. Glauconite is present in matrix and associated with bioturbation and carbonaceous organic debris.

Bioturbated bsi Comprises dark-grey bioturbated The trace fossils and siltstone siltstone with a lesser percentage of their association with sand. Bioturbation occurs mainly as coal seams imply that horizontal burrows, but there are also these sediments vertical and oblique burrows. accumulated in low- energy environments.

Carbonaceous cs A dark-grey to black carbonaceous Formed by siltstone and micaceous siltstone which is suspension settling typically massive or may be vaguely of silt, under horizontally laminated. Finely quiescent conditions, disseminated pyrite, crystalline pyrite most likely in paralic and plant fossils leaves are common. or continental settings where terrestrial vegetation contributed to the carbonaceous content.

Coal -- c Comprises bituminous coal with dull, Formed in lustrous and bright coal bands. continental fluvio- deltaic and paralic peat swamps.

48 Diamictite (From: Stanimirovic, Cross-bedded small­ Massive conglomerate 2002) pebble conglomerate {Type 2)

Massive sandstone Planar cross-bedded Trough cross-bedded Planar-laminated sandstone sandstone sandstone Figure 3.2- Examples of the facies types found in the study area. See Table 3.2 for descriptions.

49 Cross-laminated Flaser-laminated sandstone Glauconitic sandstone sandstone

Gravelly siltstone Wavy-laminated Lenticular-laminated (From: Stanimirovic, sandstone-siltstone siltstone 2002) Glauconite siltstone Figure 3.2 - Continued ....

50 3.2 Petrography

3.2.1 Introduction

Borehole core from two of the three brecciated boreholes core sequences was available for this study. Core samples from Core A and Core B were described in detail according to their macro- and microscopic characteristics. This section provides a summary and context for the descriptions of all core samples from Core A and Core B given in the appendices to this text (Appendix A and Appendix B, respectively).

3.2.2 Sample selection

The sampling of the boreholes core sequences was conducted by geologists working in the study area at the time of drilling as outlined in Chapter 1.3.3. Details regarding the methods of sample selection were obtained from the geologists who sampled the two brecciated borehole core sequences. Core samples were collected with the intention that an investigation be undertaken to establish the cause of the brecciation of the sequences. Samples were collected from specific zones of interest within the sequences and the respective stratigraphic positions were recorded (Figures 3.3 and 3.4)

For Core A, a sample of unaltered dolerite was taken from the top of the core sequence

(Sample Al). The next four samples were selected for comparison with the unaltered sample and included dolerites with unusual characteristics and noted by the samplers to be somewhat atypical in colour and appearance. Moving down through the remainder of the Core A, numerous samples were taken at semi-regular intervals at sections of interest, where and when changes in the general characteristics (such as composition and clast size) of the breccias' were observed.

A similar sampling procedure, as outlined for Core A above, was followed for Core B. A sample of unaltered dolerite was taken from the top of the core sequence (Sample Bl) followed by five dolerite samples for comparative purposes. Core samples were then taken at more regular intervals as brecciation became apparent, and include substantial samples of dolerite and breccia.

51 Surface Om ' 10m

SampleA1 120m

20m SampleA4

130m SampleA5 SampleA6 30m

SampleA7 140m

40m

Sample AS 150m

50m SampleA9 160m Sam~leA10 Sam leA11 60m

170m SampleA12 70m SampleA13 SampleA14 SampleA15 180m

SampleA2 80m SampleA3 EOH 190m

90m Legend: .:J Overburden • Mudstone/shale Sandstone 100m ill[] • Dolerite m1 Siltstone Breccia and I or Alternatingsandstone I BJ altered lithologies and siltstone 110m ' Figure 3.3 - Location of samples taken within brecciated core sequence A. See Figure 1.3 for the location of the borehole.

52 Surface ' Sample B4 -----+

SampleB1

Sample B5 ----+ Sample B2 -----+

Sample B3 ----+ SampleB6

~=m~~§~ SamPle ~9 ----- Sample 610-----+

Legend: Sample B11 -----+ .:J Overburden Sample B12 ----+ J;i::iJ I sandstone

• Siltstone

~!~:~ill Alternating sandstone a:J and siltstone Sample B13 -----+ • Mudstone I shale Sample B14 ----­ • Dolerite Sample B15 -----+ Breccia and I or I altered lithologies

Figure 3.4- Location of samples taken within brecciated core sequence B. See Figure 1.3 for the location of the borehole.

53 A borehole core sequence of normal, undeformed core from the study area was obtained in the early stages of this study, from a colliery conducting routine drilling. The core samples from Core A and B, along with core samples from the standard core

(referred to hereafter as 'Standard Core samples' and described in Appendix C), were cleaned, photographed and described in detail. They were then sawn in half and photographed once more. One half of each sample was retained for reference. The other half was used for making thin sections for petrographical and mineral chemical studies (Chapter 3), in addition to the remainder being processed for bulk rock geochemical studies (Chapter 4) and stable isotope studies (Chapter 5) on calcite veins.

All samples are described in this chapter according to their lithological and petrographical characteristics and are named in increasing alphabetical order, corresponding to the relative depth at which the samples were taken from each sequence. Samples from Core A are numbered Al to A15 and the locations of the samples within the borehole core sequence are show in Figure 3.3. Samples from Core B are numbered Bl to B15. Borehole core samples up to 1.5 m in length were obtained for this core and as such they were sectioned and grouped for ease. Figure 3.4 shows the locations of the Core B samples within this borehole core sequence.

3.2.3 Petrography of the brecciated core sequences

Keeping the typical lithologies present in the study area in mind (Section 3.1), the examination of the individual brecciated core sequences as a whole, reveals the following similar characteristics in each of the brecciated cores:

1. All breccia clasts present within the sequences are locally derived sedimentary

rocks or dolerite fragments and are angular and randomly orientated with

varying sizes.

2. The clast-supporting breccia matrix consists of angular to sub-angular grains of

(but not restricted to) quartz with medium-to-low sphericity, microcline,

muscovite and carbonaceous materials, all cemented with calcite. Most grains

show moderate to intense fracturing; the fractures are often filled with calcite.

54 Closer examination reveals differences between breccia samples in addition to inconsistencies within individual samples. Representative samples from the brecciated core sequences (as referred to in the text below), as selected from the full set of samples (Appendix A and Appendix B respectively), are used here to illustrate these differences (Figure 3.S and Figure 3.6).

• The abundance, distribution and type of breccia clasts, coaly fragments and

dolerite fragments, varies between samples (compare: Samples AS-a, A7 and A9-

a, Figure 3.S; Samples BlO-a, B12-a and B13-c, Figure 3.6). There may be many or

relatively few breccia clasts and/or almost exclusively one type of clast lithology

(e.g. coaly clasts) or fragment type (e.g. altered dolerite) present.

• The size of breccia clasts and dolerite fragments is variable between, and even

within, individual samples (compare: Samples A7 and A9-a, Figure 3.S; Samples

BlO-a and Bll-b, Figure 3.6).

• The colour and composition in the clast-supporting breccia matrix is varies from

light cream/grey to dark grey (compare: Samples AS-a and A9-b, Figure 3.S;

Samples BlO-a and Bl2-a, Figure 3.6). Colour variations in the breccia matrix are

largely dependent on the amount of carbonaceous material present in the

matrix.

• The grain sizes present in the breccia matrix are inconsistent and larger grains of

sediment in the breccia matrix are often fractured and filled with finer matrix

material. There are also dolerite fragments less than 2mm in size present within

the clast-supporting breccia matrix.

• The porosity of the breccia itself varies (compare: Samples A7 and AlS-b, Figure

3.S; BlO-a and B13-d, Figure 3.6); it is, to some extent, proportional to the

abundance of carbonaceous material present in the breccia matrix.

Sediment dominated breccia occurs within 'vein-like' features throughout certain samples (Samples A3, A6, AlS-c; Appendix A) irrespective of whether the host rock is of igneous or sedimentary origin. The breccia in these 'veins', have the same characteristics

55 and composition as that of the general clast-supporting breccia matrix. Breccia 'blebs'

present in sedimentary hosts, crosscut and offset laminations (as in Sample A15-c,

Figure 3.5), implying the 'intrusion' of breccia into the host.

Figure 3.5 - Representative breccia samples from Core A. Facies labels correspond to those as indicated in Table 3.2. (a) Sample AS-a; (b) Sample A7; (c) Sample A9-a; (d) Sample A9-b; (e) Sample A15-b; (f) Sample AlS-c. See Appendix A for full descriptions and photomicrographs of these and other core samples from Core A.

56 Figure 3.6 - Representative breccia samples from Core B. Facies labels correspond to those as indicated in Table 3.2. (a) Sample BlO-a; (b) Sample Bll-b; (c) Sample B12-a; {d) Sample B13-c; (e) Sample B13-d. See Appendix B for full descriptions and photomicrographs of these and other core samples from Core B.

Brecciation is not apparent within the upper portions of the brecciated borehole core sequences. Dolerite samples taken at 15 m below surface (Sample Al) in Core A and at

46, 52 and 65 m (Sample Bl, B2 and B3) in Core B, show typical macro- and microscopic

57 characteristics of unaltered dolerite (Figures 3. 7 and 3.8). These samples are dark to light grey, aphanitic(< 1 mm grain size) and composed of 60-65 %pyroxene and 40-35% plagioclase with minor Fe- and Ti-oxides (1%), rare olivine, and localised veins filled with calcite. They have a typical igneous texture with all crystals are arranged in an irregular mesh; up to 20% of the rock constitutes phenocrysts of plagioclase (up to 1 mm in size) pyroxene (0.25 mm in size), whilst the remainder is matrix.

Alteration of dolerite in the brecciated core sequences becomes apparent as one examines dolerites located at depths below those of samples A3 and B4 in Core A and B respectively. Alteration is visible in the hand samples and under the petrographical microscope. A comparison of selected altered dolerites and their respective textures are shown in Figures 3.9 and 3.10, where in both figures they are compared to a sample of fresh dolerite from the Standard core sequence (STD-DOL 1, Appendix C).

In Core A, altered dolerite typically has an orange-brown colour, whilst in Core B the colour varies from light-green to dark grey (Figure 3.9); alteration discolouration is strongest near the edges of each dolerite sample. The variability of alteration intensity between dolerite samples is obvious on a microscopic level (Figure 3.10). Altered dolerite samples from both brecciated core sequences, are composed of corroded and altered plagioclase and pyroxene crystals; secondary minerals are optically unidentifiable and in many cases, the primary minerals are only identifiable by their form (i.e. shape and habit), possessing no other common optical characteristics of the original mineral. Plagioclase crystals are frequently re-crystallised and either partly or completely replaced by calcite (e.g. Sample B13-c; Figure 3.6), which is also present in the groundmass and in (1 mm wide) microfractures and fractures cross-cutting the samples. Pyroxene is generally altered to orange-brown crystals with larger ones being circular in shape and hence referred to as 'ocelli' (e.g. Sample A4-a, Figure 3.10).

Alteration phases are variably developed depending on the individual samples and may include sericite, chlorite, iddingsite and occasional goethite. Oxides such as titano­ magnetite and ilmenite occur interstitial to the major minerals.

58 [0] A'

'

Figure 3.7 - Unaltered dolerite core samples from the upper sections of Core A and Core B. {a) Sample Al; {b) Sample Bl; {c) Sample B2; {d) Sample B3. See Appendix A and B for detailed descriptions of the core samples.

Figure 3.8 - Photomicrographs of the unaltered dolerite core samples from the upper sections of Core A and Core B which correlate to the samples shown Figure 3.5 {a) Sample Al; {b) Sample Bl; {c) Sample B2; {d) Sample B3.

59 Figure 3.9 - Comparison of unaltered and altered dolerite using cut sections of core. Examples include: (a) Unaltered dolerite from the Standard Core; (b) altered dolerite Sample A4-a; (c) altered dolerite fragments in breccia from Sample A9-a; (d) altered dolerite fragments in breccia from Sample AlS-d; (e) altered dolerite fragments in breccia from Sample B13-c; (f) dolerite Sample BlS-b.

60 Figure 3.10- Photomicrographs comparing unaltered and altered dolerite (plane polarised light). Examples correlate with those in Figure 3.9. Px - pyroxene; PI - plagioclase Cal - calcite (abbreviations after Siivola and Schmidt, 2007); Ox - Fe-Ti oxides; Alt.mix- mixtures of the minerals and/or alteration products. (a) Unaltered dolerite from the Standard Core. Images (b) to (f) represent altered samples. Plagioclase is identifiable by its form and pyroxene occurs as orange-brown interstitial crystals. Alteration minerals occur throughout. (b) Dolerite from Sample A4-a, shows alteration of the groundmass and pyroxene phenocrysts. (c) Dolerite fragment from Sample A9-a, shows micro-phenocrysts in an aphanitic groundmass. (d) Dolerite fragment from Sample A15-d, note the scale used. (e) Dolerite fragment from Sample B13-c, shows alteration of the ground mass and plagioclase phenocrysts. (f) Dolerite from Sample B15-b with oligophyric texture, altered ground mass and plagioclase phenocrysts.

61 3.3 Mineral Chemistry

3.3.1 Introduction

The change in the chemical composition of the primary minerals, i.e. plagioclase feldspar and pyroxene, which together constitute up to 99% of the volume of the dolerites in this study, were investigated using an electron microprobe. Although

accessory minerals were identified, their detailed chemistry lies beyond the scope of this study. The acquisition of mineral chemical data via electron microscopy offers the opportunity to investigate the nature of the alteration present in altered samples, from a chemical point of view, relative to unaltered samples from the Standard Core sequence.

3.3.2 Methodology

Selected thin sections prepared for the petrographical studies (Section 3.2) were used for electron microprobe analyses. Samples of three representative dolerite types as

present in the standard core sequence (STD-DOL 1 to 3; Appendix C) were included. Thin

sections from seven samples from each of the brecciated boreholes core sequences were analysed (including samples: A1, A3-a, A3-b, A4-a, AS-a, A9-a, A14-b; B1, B4, BS,

Bll-c, B13-b, B13-c and B15-a). The thin sections were cut in such a manner as to

include both the dolerite fragments and the breccia matrix on a single slide.

Electron microprobe analyses were carried out using a Jeol 733 Superprobe at The

Central Analytical Facility of the Faculty of Science, University of Johannesburg

(SPECTRAU. Energy-dispersive X-ray analyses, Wavelength dispersive (WDS and EDS respectively), secondary electron (SEI) and back-scattered electron (BSE) imagery where employed to identify and/or confirm mineralogical compositions and investigate the mineral chemistry of selected.

The acquisition of the mineral chemical data was performed using WDS under 15 kV and

20 IJ.A with a beam diameter of 5 IJ.m, after calibration of the microprobe using suitable standards (mounted in 25 mm diameter polished sections). For altered dolerite samples,

62 adjustments to the beam current down to 10 llA and beam diameter up to 10-20 llm were needed, due to difficulties encountered in the acquisition of high-quality, reliable mineral chemical analyses under a more focused (therefore high energy) electron beam.

Loss of data quality in altered samples is attributed to their increased volatile content, which cannot be analysed or determined with the microprobe. The release of volatile material from the sample surface was observed under transmitted light, when these samples were subjected to the vacuum and a scanning electron beam.

The data obtained in the mineral chemical investigation are suitable for investigating the alteration of dolerite samples with the focus of the investigation directed towards the nature of the chemical change in the dominant mineral types. Thus for each thin section of unaltered and altered dolerite analysed, plagioclase and pyroxene crystals, or respective remnants thereof, were identified by their form and relative grey levels and analysed separately/independently via WDS point analysis. Average compositions of each major mineral are reported in this section. The mineral chemical data acquired for each major mineral in individual samples is reported in Appendix D. Accessory and alteration phases (which are variably developed, depending on the individual sample) initially noted during observations under the petrographical microscope, were confirmed via EDS analyses; no detailed characterization or mineral chemical data acquisition was attempted as such details lie beyond the scope of this study. Similar approaches with detailed characterisation of the primary minerals and the identification

(only) of accessory/alteration minerals have been carried out in literature on the Karoo rocks (e.g. Cox and Bristow, 1984).

3.3.3 Mineral chemistry of the unaltered dolerites from the Standard Core sequence

Four dolerite samples were selected from the Standard Core for mineral chemical analyses. These include samples from the three dolerite types present (STD-DOL 1 to 3, described in Appendix C) and an additional sample from the margin of the third dolerite type. The standard dolerite samples are composed primarily of plagioclase feldspar and pyroxene. Accessory minerals include iddingsitic olivine, ilmenite and titano magnetite

63 (Figure 3.11); ilmenite is formed after titianiferous magnetite which is present in minor amounts and sometimes occurs as inclusions within pyroxene. For both plagioclase and pyroxene, the difference in chemistry between their phenocrysts and corresponding crystal types in the matrix was found to vary insignificantly. Both plagioclase and pyroxene show compositional/chemical zoning.

Figure 3.11 - BSE images of the unaltered dolerites: (a) and (b) are from STD-DOL 1. (c) and (d) are from STD-DOL 2 and 3 respectively (Appendix C). Cpx- clinopyroxene; PI - plagioclase; lim - ilmenite; 01 -Olivine; Chi -chlorite (abbreviations after Siivola and Schmidt, 2007).

Plagioclase cores (with higher grey levels than the rims in the BSE images - Figure 3.11) are more Ca rich (An79-48 Abso-2o Or2-1; Xca = 0.48 to 0.80, [Xca=Ca/(Ca+Na+K)]) than the more Na rich rims (An49-28 Abn-48 Or1-2;Xca = 0.21 to 0.48) (Figure 3.12). Pyroxene is dominantly augite with minor pigeonite in the Standard Core dolerites. The Al 20 3 content varies between core and rim in the augite with the cores richer in Al 20 3 (1.24-

2.03 wt%) than the rims (0.92- 1.24 wt%). Pigeonite has up to 1 wt% less Al 20 3 (0.56- 0.97 wt%) than augite. Pyroxene cores (which have lower grey levels in BSE images -

64 Figure 3.11) are more Ca- and Mg-rich (Wo41-1o Ens9-36 Fs34-1o; XMg = 0.52 to 0.84,

[XMg=Mg/(Mg+Fe)]) than the Fe-rich rims (Wo34-1l En44-29 Fs4G-29; XMg = 0.43 to 0.58).

(a) Or (b) KAIS130. ., Pyroo

Alkali feklspa~

Plgeonite ..,"' "" Clinoferro1ihte

Figure 3.12- Ternary diagrams showing (a) feldspar and (b) pyroxene crystal compositions from the dolerite samples from the Standard Core sequence.

3.3.4 Mineral chemistry of the altered dolerites from the brecciated core sequences

Seven dolerite samples were selected from both brecciated core sequences A and B. The samples include less-altered to heavily-altered dolerite extracted from the brecciated sequences. The alteration in samples of dolerite from the brecciated core sequences

was shown previously to be visible in the hand samples and under the petrographical

microscope (Section 3.1.3, Figures 3.9 and 3.10). The alteration is evident in the BSE

imagery, when comparing these images (Figure 3.13) to those BSE images from the standard samples (Figure 3.11). In the altered samples, the primary minerals, i.e. plagioclase feldspar and clinopyroxene and/or their remnants can usually be identified in the BSE imagery because they often maintain at least some of their original form, i.e. plagioclase crystals generally maintain their prismatic shape and pyroxenes are more irregularly shaped with slightly higher grey levels. This made it possible to analyse these two minerals types individually and investigate the change in the chemistry of these minerals relative to their counterparts from the Standard Core samples. Titano­ magnetite occurs as tiny interstitial crystals (due to its bright occurrence in the BSE images. Alteration minerals identified via EDS include sericite and chlorite which are

65 present in variable amounts in all altered samples replacing potions of plagioclase and

pyroxene crystals. Calcite and rare epidote occur in micro-fractures with possible

zeolite. Plagioclase crystals show partial replacement by calcite in the more heavily

altered samples. lddingsitic olivine and iddingsite also occur in variable amount in the

matrix of the altered samples. The reddish-brown discolouration in altered samples (as

noted in Section 3.1.3, Figure 3.10) is due to the oxidation of iron.

Varying degrees of alteration are present both within individual samples and between

different core samples from the brecciated core sequences. It was found that the

observed intensity of alteration as seen in Figure 3.13 (i.e. the visible difference

between altered samples in Figure 3.13 and the standards as shown in Figure 3.11)

increases with sample number. Given that the sample number increases with depth at

which such a sample is located within a brecciated core sequence, this implies a more or

less concomitant increase in alteration with depth.

The dolerite samples from both brecciated core sequences show similarities with

respect to the changes in the mineral chemistry that have taken place with regards to

their primary mineral constituents. In both Core A and B, less altered samples located in

the upper regions of the brecciated sequences contained plagioclase crystals with

similar compositions to the unaltered standards. Less-altered plagioclase in Core A has

An 5s Ab40 Or2 (Xca = 0.58) and those in Core B have Ansg Ab3 9 Or2 (Xca = 0.60). Plagioclase crystals in more heavily altered dolerite samples located deeper within the

brecciated core sequences showed a significantly less Ca content relative to plagioclase

crystals from dolerite samples in the Standard Core (Figure 3.14). The altered

plagioclase crystals in Core A have an average composition of An 7 Ab 40 Or 35 (Xca = 0.04)

and those in Core B average Ana Abs9 Or 11 (Xca = 0.003). Individual phenocrysts sometimes have less altered cores with highly altered rims. Many samples from Core A fall into the immiscible region on the Or-Ab-An diagram (Figure 3.14), a clear indication

that even though the crystal could be visibly identified as remnant plagioclase, the

mineral chemistry no longer reflects that of its original composition.

66 Figure 3.13 - BSE images of altered dolerite from the brecciated core sequences. Remnants of the primary minerals are identifiable by form (as discussed in the text). Px - pyroxene; PI - plagioclase; lim - ilmenite (abbreviations after Siivola and Schmidt, 2007). Areas labelled 'Ait.mix' indicate mixtures of the minerals and/or alteration products. Bright spots represent Fe­ Ti oxides such as titano-magnetite or ilmenite. Alteration minerals occur along crystal margins of primary minerals and interstitial to the ones highlighted in images. Images (a), (b) and (c) are from samples A3-a, A4-a and AS-b respectively; images (d), (e) and (f) are from samples B4, 813- b and 813-c respectively.

67 {a) CoreA Or {b) Core B Or

• Plagioclase cores • Plagioclase rims • Plagioclase phenocryst cores • Plagioclase phenocryst rims

Figure 3.14 - Compositions feldspars crystals from {a) Core A and {b) Core B. Less altered samples are highlighted in dark grey and more altered sample are highlighted in light red.

Unaltered or less-altered pyroxene from dolerite samples occurring in the upper regions of Core A have Wo3o En4o Fs29 (XMg =0.58) and those in Core B haveWo34 En43 Fs22 (XMg

= 0.66). Altered pyroxenes show lower concentrations of Ca (Figure 3.15) relative to the least altered samples. Altered pyroxene in Core A has Wo 18 En 33 Fs 40 (XMg = 0.44) and those in Core B have Wo1 En 38 Fs46 (XMg =0.41). In Core A, some plagioclase phenocrysts are partly replaced by calcite and minor epidote resulting in high Wo values as seen in

Figure 3.15.

{a) CoreA Wo {b) Core B Wo

• Pyroxene cores • Pyroxene rims • Pyroxene phenocryst cores • Pyroxene phenocryst rims

Less altered pyroxene ~~i\~'Jli, .•

Caloss l• "'f /'' Altered roxene

Figure 3.15 - Compositions pyroxene crystals from {a) Core A and {b) Core B. Less altered samples are highlighted in light grey and more altered sample are highlighted in beige.

68 3.3.5 Mineral chemistry of the sedimentary rocks and breccia

Energy-dispersive X-ray analyses was used only to confirm the mineralogy of the clast­ supporting matrix of the breccias samples to aid with a comparison between them and the sandstones from the Standard Core {STD-SED 1 to 3; described in Appendix C).

Figure 3.16 shows some examples of the clast-supporting matrix from Core A, in order to provide further understanding of the general mineralogy of the breccia matrix, with the breccia matrix of Core B showing the same mineralogy. The mineral grain types identified in the electron microprobe correlate well with the mineralogy as determined from the petrographical investigations. The mineral assemblage of the breccia matrix is similar to that of the sedimentary rocks of the Standard Core sequences, consisting mainly of quartz and microcline, accompanied by muscovite, biotite, macerated carbonaceous materials and calcite cement, but in varying proportions. Grains of plagioclase feldspar (oligoclase), perthite and glauconite are occasionally present.

69 Figure 3.16 - Backscattered scanning electron images of the sedimentary rock samples. Image (a) is of fresh massive medium grained sandstone (STD-SED 2). The remaining images are from Core A .Exact locations are shown within the Reference Figures (Appendix A) for each of the samples listed here: (b) and (c) the matrix of a breccia "vein" in sample A3-b; (d), (e) and (f) are from the breccia matrix in sample AS-b, A13-b, and , AlS-a respectively. Abbreviations used include: Qtz - quartz; Me - microcline; Ms - Muscovite; Bt - biotite; C - carbonaceous materials; Pth- perthite; Gl -glauconite; Cal -calcite (abbreviations after Siivola and Schmid, 2007).

70 3.4 Discussion on the nature of the brecciation in Core A and Core B

Examination of the brecciated borehole core sequences implies that a violent,

destructive event (or events) produced the breccias; the breccias contains clasts and fragments of all facies types present in the immediate study area, all of which are

intrabasinally derived. The brecciation occurred post-diagenesis (i.e. after the deposition

of the Vryheid Formation) as indicated by breccia fragments that clearly retain their

original sedimentary structures. This also implies that there was no syn-sedimentary or

soft sediment deformation.

The approximate position of the No. 4 coal seam has been carefully estimated for the

brecciated sequences by comparison with nearby borehole core logs. It is used as a datum level to plot the stratigraphic columns for the three brecciated core sequences

(Figure 3.17). The unaltered dolerite Samples A1, B1, B2 and B3 are located at approximately similar stratigraphic levels above the envisaged position of the No.4 coal seam. With reference to the No.4 seam, the following is observed:

• Brecciation in Core A (as seen in Sample A2) begins at approximately 115 m

above the seam.

• Brecciation in Core B begins at approximately 16 m above the seam, although

atypical colouration or alteration in the rocks is noted at 70 m above the seam.

• Brecciation can be confirmed for Core Cat approximately 123 m above the seam

(determined from the core log and indicated in the Figure 3.17).

The varying depth at which the brecciation becomes prominent between the sequences implies that the cause for the brecciation in each individual sequence is probably not due to a single event, because a single event would have most likely affected each sequence in a similar manner, in addition to effecting all of the surrounding boreholes.

Furthermore, these events are not linked to the stratigraphic position of the thick No. 4 seam coal seam, because the brecciation extends well below the position of the seam

(particularly in Core C).

71 Core 8 ·~~lr 'Om

Core A ro ·"- [_ :30-r .._., S¥nple61

\:let'

'fL·~, Confirmed r br&cc:.atiOn I"" I ~·J~· l [ [ ...... , i 1'00' -·3 [ 1'1)"1" 5Amp.. 84 .c 1: ~~;; ;,,, ! I IIF'J SampieA4 rc- ~~; "''"

.·;;..- ==~ n .. ' Samplt85 s.tnpltA7 rr '"r··~r• s.mp~~tA8 ' '~C•·

S&l!'lpieB6 !Mrnpii!A9 .,·oo..,r- =~w i"'" Bl! il ,.,~ SampleS tO s.n-p.A12 s.mple-811 SimPeA13 I Sampllt812 ~A14 r~· SempeA15 ,.~ ;>1()'"1" ~813 i EOH >Or s.mo~eB14 J~~o ... Samplit81S

EOH

Conflfmed brecclattOn··

EOH Figure 3.17 -A comparison of the three brecciated core sequences plotted with reference to the theoretical position of the No.4 coal seam.

72 If each brecciated core sequence is examined as a whole, they may be subdivided into groups, broadly based on the presence or absence of brecciation, the type of brecciation and nature of sequences and the clast or rock fragments which they contain. Figure 3.18 shows such groupings for Cores A and B, made possible with the aid of the core logs and the samples. Two relevant similarities are given below:

• The rocks which constitute the breccias were intensely fragmented and

displaced from their original stratigraphic positions to their current locations.

However, the clasts and rock fragments which are found within the breccias

appear to have been displaced by less than 20 - 30 m from their original

positions (for example, within 15 m to 20 m above and below the theoretical

position of the No. 4 coal seam, the breccias contain a much higher abundance

of coal clasts and coalified materials relative to the rest of the sequences).

• The brecciation events caused severe disturbances during the displacement of

rock fragments and clasts, as indicated by the irregular orientations of clasts and

rock fragments within the breccias.

The uppermost dolerites in the sequences show far less brecciation and have typical doleritic textures (Section 3.1.3), but fragments found at depth in these sequences have unusual colour and textures (Sections 3.1.4}. Both the petrography and mineral chemistry confirm the presence of alteration (Section 3.4), with the occurrence typical alteration minerals such as chlorite and sericite. A syngenetic or early epigenetic hydrothermal alteration phase most likely occurred, resulting in the alteration seen in many dolerite samples (Section 3.4.4). Any large-scale fluid alteration unrelated to breccias would have had a pronounced effect on any surrounding stratigraphy, however all surrounding boreholes are completely undisturbed. Evidence of the presence of fluid during the brecciation event is present in Sample A15-c (Figure 3.5); the breccia matrix has 'intruded' the siltstone host rock, a common feature of sediment fluidisation (Curtis and Riley, 2003; Svensen et a/., 2010), and a feature that is difficult to explain without fluid assisted transportation of the breccia.

73 Core B Su~ece Om

overburden "m

Core A 10m Surl'ace Om 30m

overburden unaltered l=--· ~om dolerile unaltered dolerite "'"' (sedminent) :~~

i::J.O""

40•-

undisturbed sedminents so.,-, unaltered dolerite

Legend: 60m ~O...Mburden

brecciated dolerite and )Om EJSlttstane sediment breccia Alternatit\l~cbtone IIJ fnd siltstone undisturbed • Mucbtone{shale ~~~- sedminents brecciated Owybtilhte and altered dolerite ~~~ • Granite aa,emll!nt • "'"'" •IIJ After.-dlitholo&les sediment less Dolmte breccia disturbed w/larger sedminents • Co•l clast incl dolerite - ,=-- sedminent breccia 140m (smaller 10m clasts)

sediment ~~-c- 15Q.r 80m breccia wl varying clast sizes incl.coal &porus sediment breccias \n..-un:tL.I\ 1-ohon"\ breccia wl !!~~0..11 varying clast sediment sizes incl. coal : breccia Icc- incl. porus sediment breccia i80"" breccia wl ~-c~ smaller clasts lower part has sediment many dolerite brecciawl clasts EOH ~go,.., smaller clast sizes, veined dolerite : no coal underlain by sediment breccia Figure 3.18- Groupings of similar sections in brecciated borehole core sequences A and B.

74 CHAPTER4

GEOCHEMISTRY

4.1 Introduction

Bulk rock geochemical data acquired in this study, includes selected samples of

unaltered and altered dolerite and the clast-supporting breccia matrix from the

brecciated borehole core sequences, which are compared to dolerite samples from

the Standard Core. The geochemical characterisation has two objectives: 1) The

characterisation of the samples with respect to their general composition and

tectonic setting (or provenance for sedimentary rocks). The classification of samples

in the context of this study is included, not only as a means of showing how the

standard dolerite samples relate to the general Karoo dolerites and sediments, but

primarily as a means of showing the dissimilarities and/or effects of alteration

between the standard samples and those sourced from the brecciated borehole core

sequences. 2) The second (and the main) objective was to determine the nature and

effect of alteration present in samples sourced from the brecciated sequences,

which was noted during the petrological and petrographical studies.

4.2 Methodology

Seven fresh dolerite samples were selected from the standard core sequence at 7,

22, 23, 26, 35, 45 and 49 meters below surface, where the dolerites appeared to

show some degree of textural variation. They are classified into three types based on

textural and geochemical similarities and are described in Appendix C. Three fresh

sedimentary rock samples of coarse-grained sandstone, medium-grained sandstone

and fine-grained sandstone were selected from the standard core sequence at 26, 60

and 94 metres below surface respectively. They are described in detail in Appendix

C. A total of 40 samples of both igneous and sedimentary rocks were selected for

bulk rock geochemical analyses which include ten samples from the standard core

sequence and 15 samples from each of the brecciated borehole core sequences.

75 Included in the 15 samples selected from Core A and B, were 10 dolerite samples and 5 samples of the clast-supporting breccia matrix. Sample selection was governed by the availability of each rock type concerned at various locations within the sequences, although effort was made to source samples from the cores at regular intervals; it follows that repeat analyses of certain samples was permitted. Dolerite and clast-supporting breccia samples extracted from Core A include: dolerite- 2x A1,

3x A3-a, 1x A3-b, 2x A4-a, 2x A14-b; and breccia - 1x A2, 1x AS-a, 1x A7, 1x A9-b 1x

A15-b. Samples sourced from Core B include: dolerite - 2x B1, 1x B3, 1x B4, 2x BS, 1x

Bll-a, 2x Bll-c and 1x B15-b; and breccia: 1x B9-c, 1x B10-a, 1x B12-a, 1x B13-d, 1x

B14-a. The locations of the samples from both brecciated sequences were discussed in Chapter 3.2 and are indicated in Figure 3.3 and 3.4. Descriptions of all samples from Core A and Bas listed above are provided in Appendix A and B respectively.

Each core sample was cut in half using a diamond saw. For dolerite samples, approximately 10 em lengths pieces were processed; where only smaller, individual dolerite fragments were available, these were cut individually from the core sample and combined to an approximately equal amount. The clast-supporting breccia matrix is naturally poorly sorted, so extreme caution was taken when cutting samples to ensure some degree of homogeneity in the 10 em sections. All samples were crushed by hand and milled with a chrome-steel mill for 30 - 60 seconds to reduce fragment sizes, before milling again for 3- 5 minutes with an agate mill. The resulting powder was collected into 20 ml plastic polytops and sent to Acmelabs,

Vancouver, Canada for bulk geochemical analyses.

At Acmelabs, major and some trace elements were determined by inductively coupled plasma emission spectrometry (ICP-ES) following a lithium metaborate I tetraborate fusion and dilute nitric digestion of a 0.2 g sample. Rare earth and refractory elements were determined by inductively coupled plasma mass spectrometry (ICP-MS) following a lithium metaborate I tetraborate fusion and nitric acid digestion of a 0.2 g sample. In addition, a separate 0.5 g split was digested in hot

(95°C) aqua regia and analysed by ICP-MS to report precious and base metals. Loss on ignition (LOI) was calculated by the weight difference after ignition to 1000°C. The complete set of geochemical data is provided in Appendix E. Elements with low

76 detection limits/uncertainties are also reported (Be, Sn, W, As, Cd, Sb, Bi, Ag, Au, Hg,

Tl and Se) but are not used in the geochemical study.

4.3 Geochemistry of the unaltered and altered dolerites

4.3.1 Classification and tectonic setting

A summary of the major element bulk rock geochemistry of the dolerites is provided

(Table 4.1). The complete set of geochemical data (major, trace and rare earth element) is provided as an appendix to this text (Appendix E).

In terms of the total alkalis vs. silica plot, the fresh standard dolerite samples are basaltic to basaltic andesitic in composition (Figure 4.1). Samples from the uppermost sills in the brecciated core sequences, plot close to the standards - within the range of general Karoo Lavas - an indication of little or no effect of alteration in the chemistry of these rocks. All of the altered dolerite fragments plot to the left of the standards and fall outside the range of general Karoo lavas. Cox et a/. (1967) divided the basaltic rocks of the Karoo based on their petrographic and geochemical characteristics, into a low-Ti southern province (the Karoo Central Area) and a high­

Ti northern province (Lebombo, Botswana and Zimbabwe). Further distinct chemical types of basalts have also been identified in the Karoo (cf. Erlank, 1984). The standard dolerite samples from this study can be classified as low-Ti basaltic rocks

(Figure 1).

{b) • Standard Core {a) '' •CoreA &Coree 14 BOO 12 700 ~ 10 .! 600 .. 0 ,z 8 100 : High-Ti . Sr -1----~-- 400 ~ 6 •• • z ...., 300

... K~roo lavas 200 .. • 100 ' . Low-Ti

40 45 so 55 60 65 70 75 80 0.0 05 1.0 1.1 2.0 25 3.0 SiO,{wt%) r.o,{wt%) Figure 4.1 - Classification diagrams for the dolerite samples. (a) Total alkali versus silica diagram for the dolerites (after Le Maitre, 2002). (b) Sr versus Ti02 diagram. The samples plot in the low-Ti field (Cox eta/., 1967,). Karoo lava fields (yellow shade) are drawn using data from Duncan eta/., (1997), Jourdan eta/., (2007) and McCiintlock eta/., (2008).

77 Table 4.1 - Major element data of the dolerite samples for the Standard Core, Core A and Core B. The complete geochemical data set can be found in Appendix E. The Mg-number, is the molecular proportion of Mg2+/ (Mg2++Fe2+) (Downes et at. 1995). Core Set: Standard Core . Sample No. 1 2 3 4 5 6 7 Average

' Si0 2 51.13 51.99 51.72 51.43 52.03 52.40 50.20 51.56

Ti02 0.91 1.17 1.15 1.14 1.52 1.55 1.77 1.32 Al 20 3 14.37 13.65 14.23 14.13 13.10 13.06 15.06 13.94

, Fe 2 0 3 10.63 12.26 11.69 11.78 12.86 13.15 12.31 12.10 MnO 0.16 0.19 0.19 0.18 0.19 0.19 0.10 0.17 MgO 8.53 6.05 5.78 5.83 5.39 5.77 3.27 5.80 CaO 10.04 9.99 10.29 10.07 8.74 8.53 6.24 9.13

Na 20 2.14 2.43 2.41 2.72 2.75 2.73 3.34 2.65 KzO 0.73 0.86 0.83 0.83 0.92 0.87 1.02 0.87 PzOs 0.14 0.21 0.20 0.20 0.21 0.23 0.27 0.21 , Mg# 65.05 53.37 53.42 53.44 49.29 50.44 38.12 51.88 LOI 0.90 0.90 1.20 1.40 2.00 1.20 6.10 1.96 , Core Set: Core A 1 2 3 4 5

. Si0 2 51.38 51.16 51.05 48.08 48.14 50.78 36.04 36.10 35.83

Ti02 1.19 1.19 1.18 1.36 1.36 1.06 1.35 1.37 2.09

Al 2 0 3 14.45 14.50 14.68 17.59 17.59 16.53 16.46 16.57 20.89 1 Fez03 12.17 12.28 12.05 9.03 8.94 7.85 10.68 10.56 13.07 MnO 0.19 0.19 0.19 0.09 0.08 0.10 0.29 0.29 0.26 0.27 . MgO 5.87 5.83 5.89 5.59 5.49 5.10 2.79 2.75 3.33 3.34 I I CaO 10.19 10.26 10.37 7.77 7.74 8.33 12.43 12.49 2.58 2.56 i

Na 2 0 2.39 2.38 2.49 3.00 3.00 2.72 2.60 2.61 2.08 2.08

K20 0.71 0.70 0.50 0.48 0.47 0.74 0.48 0.48 0.90 0.91;

P2 0s 0.19 0.18 0.19 0.22 0.22 0.13 0.21 0.21 0.59 0.58 Mg # 52.80 52.41 53.13 58.95 58.75 60.11 37.73 37.66 37.15 37.32 , LOI 1.00 1.10 1.10 6.50 6.70 6.30 16.40 16.30 18.10 18.00 • Core set: Core B . Sample No. 1 2 3 4 5 6 7 8 9 10

. Si0 2 51.76 51.60 51.19 41.75 38.26 38.03 45.86 41.71 41.99 41.21

Ti0 2 0.95 0.94 1.18 1.46 1.30 1.30 1.39 1.37 1.37 1.00

• Alz0 3 14.69 14.89 14.42 18.45 15.93 15.81 17.18 17.65 17.66 13.31

Fez0 3 10.38 10.36 12.42 9.88 10.53 10.60 14.78 14.84 14.77 11.27 i i MnO 0.16 0.16 0.19 0.19 0.29 0.29 0.05 0.08 o.o8 o.26 1 ; MgO 7.83 7.80 5.93 2.60 2.03 2.04 6.41 6.95 6.89 4.70 I : CaO 9.83 9.89 10.41 11.43 13.28 13.34 1. 70 5.40 5.35 12.37

Na 20 2.34 2.37 2.41 2.89 2.81 2.79 5.09 3.27 3.26

K2 0 0.62 0.62 0.71 0.87 0.97 0.97 0.58 0.63 ' PzOs 0.12 0.12 0.18 0.24 0.21 0.21 0.23 0.22 Mg# 63.63 63.59 52.55 37.90 30.90 30.86 50.15 52.07 LOI 1.00 0.90 0.70 9.90 14.10 14.30 6.40 7.50 -~·-·--·-·-·---...... ~------

The rocks of the Karoo Supergroup show subtle differences in their major element chemistry. The overwhelming majority of sills, dykes and sheet intrusions show no obvious variation, and 96% of them have an MgO content of between 5 - 8 wt%

(Erlank, 1984; Marsh and Eales, 1984). They do, however, show more significant trace element differences and may be distinguished on this basis (McCiintlock eta/.,

78 2008). The fresh dolerites from this study show low Zr/Y and but high Ti/Zr ratios- a typical feature of low-Ti Karoo basalts (Figure 4.2) (Cox et a/., 1967; Duncan and

Marsh, 2006; Erlank, 1984). Both the standards and the samples from uppermost sills in the brecciated sequences are sub-alkaline, straddling the dividing line between the tholeiitic and calc-alkaline series fields in the AFM diagram (Figure 4.2).

(FeOtotall (a) (b) F

160 • Standard Core +CoreA I!.CoreB 140 Tholeiitic series 120' Karoo I!. •• lavas Ti/Zr • 100

80 ,_.. High·Ti ~ 60 low-TI -Katoo(avas Calc-alkaline series 4Qc 2 4 6 8 10 12 Zr/Y A M (Na20+ K20) (MgO)

Figure 4.2 - (a) Plot of incompatible element ratios for the unaltered and altered dolerite samples, showing low Zr/Y and high Ti/Zr ratios). (b) AFM diagram (Irvine and Baragar, 1971). Karoo lava fields draw using data from Duncan et a/., (1997), Jourdan et a/., (2007) and McCiintlock eta/., (2008).

The alteration box plot after Large et al. (2001) relates whole-rock geochemistry to potential alteration minerals present in the samples, in terms of two alteration indices. It is used to aid in determining which dolerites samples from the brecciated sequences are most altered (Figure 4.3). The plot relies on 1) the Ishikawa alteration index (AI), as defined by Ishikawa et al. (1976) to quantify the intensity of sericite the chlorite alteration [AI= 100(Mg0 + K20)/(Mg0 + K20 + CaO + Na 20)]; 2) and the and the chlorite-carbonate-pyrite (CCPI) index to distinguish samples with elevated chlorite content within any altered volcanics data set [CCPI = 100(Fe0 + MgO)/(FeO +

MgO + Na20 + K20)] (Large eta/., 2001). The box of least altered rocks plots in an area in the centre of the box plot with AI values varying between 20 and 65, and

CCPI values varying between 15 and 85. Rocks of mafic, intermediate and felsic have

CCPI values of between 65-85, 40-65 and 15-40 respectively.

79 Epidote/calcite Chlorite 100 ...... + Standard Core 90 ...... •coreA ...... &Core B 80 ...... , .. 70 -+-- ' ...... ep-cc-ab ------~...,------...... 60 ...... D: .... u 50 ...... u ...... 40 ------~-.:: ...... sericite 30 ...... 20 ""-.,, ...... 10 Albite K-feldspar 0 0 10 20 30 40 50 60 70 80 90 100 AI Figure 4.3 - Alteration box plot showing the degree and potential types of alteration of the dole rites samples from the standard and brecciated core sequence (after Large eta/., 2001).

The standard samples (except one- Type 1- which has a more chlorite in the matrix

relative to the other standards) fall within the field for least altered basalts. Both

core A and core B samples plot similarly on either side of the standard samples. The

samples plotting to the left of the standard samples are possibly affected by epidote

+ calcite ± albite alteration; this is confirmed in the petrography of these samples

(Samples A4-a, B4, BS and B15-b), which all show replacement of plagioclase and

pyroxene by calcite (primarily) and epidote (to a lesser extent) in the thin sections

(Figure 4.4); epidote and calcite is a common product of diagenetic alteration in volcanic rocks of mafic composition (Large et a/., 2001; Gifkins et a/., 2005). Furthermore the mineral chemistry also confirms the existence of albitisation in

plagioclase remnants (see Figure 3.14).

The samples plotting to the right of the standard samples are possibly affected by chlorite-carbonate hydrothermal alteration; these samples (Samples A14-b, B11-a and Sample Bll-c) contain chlorite with lesser amounts of carbonates within the sample matrix.

80 Figure 4.4- Photomicrographs showing alteration via the replacement of primary minerals by calcite (visible with weak pearly colours) and epidote (with higher order interference colours): (a) Sample A4-a, a plagioclase phenocryst is almost completely altered showing abundant calcite replacement, (b) Sample B4, (c) Sample BS and (d) Sample BlS-b have primary minerals replaced by variable amounts of calcite and epidote.

The tectonic discrimination of the Karoo basalts is a challenging exercise and a

"problem area for inferring tectonic setting from basalt geochemistry" - Duncan

(1987). Many authors have proposed a numbers of models to explain the origin of and processes involved in the production of these rocks, ranging from continental rift to subduction related models, which may or may not involve various crustal contamination mechanisms (Anderson, 1994; Arndt et a/., 1993; Cox, 1978, 1991; Cox et a/., 1984; Duncan, 1987; Ellam et a/., 1991; Froidevaux and Nataf, 1981; Hawkesworth eta/., 1984, 1999; Marsh and Eales, 1984).

Based on immobile trace elements and log-ratio transformation - a technique recommended for a correct statistical treatment of compositional data - Agrawal et a/., (2008) proposed a series of discriminant function diagrams for mafic and ultramafic rocks. These discriminant diagrams have been successful with mafic and ultramafic rocks occurring in tectonic settings such as island-arc, continental rift,

81 ocean island, and mid-oceanic ridge (op.cit). Considering the role of alteration, this study evaluated the Karoo dolerite samples in the Agrawal et a/., (2008)

discrimination diagrams which uses immobile elements such as La, Sm, Nb, Th and

Yb (Figure 4.5), therefore also providing a test for signs of alteration from the trace element data obtained for dolerite samples from the brecciated core sequences. The

samples fall mainly into the island arc basalt and MORB fields. There is also overlap

into the continental rift field. Karoo basalts have been known to plot largely in the

island arc (lAB), continental rift (CRB) fields on previously proposed geochemical

discriminant diagrams (Duncan, 1987), although there are many known variations

and exceptions, such as the late-stage MORB-Iike dolerites near the present-day

continental margins which are considered to be of asthenospheric origin (op.cit; cf.

Erlank, 1984). The data from this study align themselves with the low-Ti Karoo

basalts as expected. A possible explanation for the above observations is crustal contamination, which most likely occurs in both the high-Ti and low-Ti rocks.

8 • Standard Core +CoreA 6 MORB ACoreB

4

2 N c~ 0 -2 CRB -4 lAB

-6

-8 -8 -6 -4 -2 0 2 4 6 8 Dfl Figure 4.5- Discriminant function tectonomagmatic discrimination diagram based on natural logarithm-transformed ratios of La, Sm, Nb, Th and Yb. The tectonic settings shown are: island arc (lAB), continental rift (CRB) and mid-ocean ridge (MORB). The equations for computing the DF1 and DF2 functions (x- and y-axes) are: (1) DF1 = 0.3305 In (La/Th) - 0.3484 In (Sm/Th) - 0.9562 In (Yb/Th) + 2.0777 In (Nb/Th); (2) DF2 = -1.1928 In (La/Th) - 1.1989 In (Sm/Th) - 1.7531 In (Yb/Th) + 0.6607 In (Nb/Th); (Agrawal et a/., 2008). Karoo lava fields were draw using data from Duncan et a/., (1997), Jourdan eta/., (2007) and McCiintlock eta/., (2008).

82 4.3.2 Comparison of geochemical characteristics of dolerite samples

There are at least two, but frequently three dolerite sills present in the study area, as inferred from the standard core sequence and borehole core logs. They are usually located within 100 meters from the surface. The upper sill (a Type 1 dolerite - samples 1 & 2, Table 4.1) is unique in that it has a high magnesium content relative to the lower two sills (Type 2- samples 3 & 4 and Type 3- samples 5 & 7, Table 4.1).

Standard core dolerite sample 7 (Table 4.1) has the lowest Mg concentration of the set and represents the fine grained chilled margin of the lowest-most sill.

Descriptions of the standard dolerites were given in Chapters 3.2 and 3.3 and full descriptions are provided in Appendix C.

The Standard Core samples show little chemical variation in general (Figure 4.6). This is particularly true for their silica content which ranges between 50.2 wt% and

52.4 wt% Si0 2. The increase in silica content with decrease in depth, in addition to an inversely proportional relationship between the silica and magnesium content of the standard samples (Table 4.1) can be attributed to differentiation. The effect of fractional crystallisation is supported by increasing and decreasing regression lines with dilution (Figure 4.6)

Dolerite samples from both Core A and Core B show a loss on ignition (LOI) of

1-18% (Appendix E). Changes in the major element compositions of the altered samples are illustrated via the element variation diagrams (Figures 4.6 and 4.7). The

Si0 2 range for the standards is narrow (50.2 - 52.4 wt%) (Table 1.1 and Figure 4.6), but those of the brecciated sequences vary markedly (Core A Si0 2 range: 35.83 -

51.38 wt%; Core B Si0 2 range: 38.03 - 51.76 wt%). MgO varies across all samples (2.03 - 7.83 wt%). More obvious trends were observed for all elements in the standard samples as shown by the regression lines in Figures 4.6 and 4.7, while trends in the altered samples are not clear (also Figures 4.6 and 4.7). Scattered concentrations of CaO (1.7 - 13.4 wt%), and K2 0 (0.46 - 0.97 wt%) are noted between all altered samples from Core A and B relative to the standards. The same is true for Al 2 0 3 (13.31 - 21.0 wt%). In general, however, altered samples show elevated Ah03 and decreased Si0 2 and K2 0 concentrations relative to the standards

83 as observed in Figure 4.6. Of those trace elements which are typically incompatible

(Rollinson, 1993), Rb, and Sr show the most variation in the brecciated sequences,

with Rb having generally lower concentrations and Sr having higher concentrations

relative to the standards (Figure 4. 7).

2.5 Standard Core 25 • CoreA •A CoreS 2.0 - Unear (Standard Core) 20 • •A Ti0 1.5 A •• •• 15 2 Al20 1 A. .. (wt%) (wt%) 1.0 ' •• 10 0.5

0.0 ---~------~------~" 0

"- "------18 60 16 ' 55 14 AA 12 ,. r~ • 50 Fer 10 A. t Si02 .. • 45 (wt") 8 - (wt%) •• .. A. A 6 40 4

0 16 6 14 A 5 12 A •A 4 10 CaO Na20 8 c A 3 (wt%) ~ .., A (wt%) 6 c • A ~ 4 • 2 • A 0 0

1.4 0.4

1.2 0.3 1.0 A. KzO o.s ~ A. 0.2 PzOs A (wt%) 0.6 l!.t (wt%) • A. • • 0.4 ~+& 0.1 0.2

_____ J ______0.0 L______--~----L--.--~'---~· ------~-- 0.0 25 35 45 55 65 25 35 45 55 65 Mg# Mg#

Figure 4.6- Plots of major elements vs. Mg# for the unaltered and altered dolerites.

84 50 700 • Standard Core 45 • + CoreA 600 40 A Core 8 - Unear (Standard Core) 35 Ia • 500 Rb 30 ._ 400 Sr (ppm) 25 3oo(ppm) 20 • A ... 15 ., • A 200 10 JI-A+ • 100 5 • 0 0

50 180 45 160 40 • 140 A 35 A 120 y 30 • 100 Zr 25 (ppm)20 ~ 80 (ppm) 60 15 10 40 s 20 0 0 12 -600

10 • 500

8 . 400 Nb 6 A • 300Ba (ppm) (ppm) 4 > ~ 200

2 ... 100

0 0

35 10.0 9.0 30 • • 8.0 25 7.0 6.0 20 Nd 5.0 Sm (ppm) 15 • A 4.0 (ppm) 10 ~ ~ 3.0 2.0 5 • LO 0 0.0 25 35 45 55 65 25 35 45 55 65 Mg# Mg#

Figure 4. 7 - Plots of selected trace elements vs. Mg# for the unaltered and altered dolerites.

Rare earth element diagrams constructed for all the dolerite samples diagrams show similar patterns (Figure 4.8). Samples 9 and 10 of Core B show more deviation relative to other Core B samples and exhibit elevated REE concentrations. It was noted that the relative concentration of REE increases with sample depth (the depth at which a samples was located is proportional to sample number), which is especially noticeable for samples 9 and 10 of Core A. All of the samples from the

85 core sequences appear to be closely related in terms of the general geochemical characteristics of their REE (Figure 4.8) i.e. there are simultaneous increases and decrease in REE concentrations between samples from individual core sequences, implying that the samples have a similar source. The samples generally are less altered with respect to the REE making the REE are less suitable for the study of the alteration of the dolerites.

100 --standard Sample 1 ---Standard Sample 2 --Standard Sample 3 --standard Sample 4 --standard Sample 5 ---Standard Sample 6 ---· Standard Sample 7

10 100

10 100

--Core B Sample 1 --- Core B Sample 2 -- Core B Sample 3 --Core B Sample 4 _..,..._.. Core B Sample 5 --- Core B Sample 6 -- Core B Sample 7 -- Core B Sample B Core B Sample 9 ....,._ Core B Sample 10

10 Ce Pr Nd sm Eu Gd Tb Ho Er Yb Lu Figure 4.8 - Chondrite-normalised REE diagrams for the unaltered and altered dolerites samples. Normalisation values as per Sun and McDonough (1989).

86 Using conventional multi-element diagrams (Sun and McDonough, 1989) (Figure

4.9), it is seen that all samples have higher concentrations of trace elements relative to N-MORB (op.cit). The relative immobility of the high field strength elements

(HFSE) and (to a lesser extent) large ion lithophile elements (LILE), underlines the relatively isochemical nature of the samples with respect to their trace element concentrations. The relative concentrations of trace elements generally increase with sample depth for the samples from the brecciated core sequences (Table 4.2).

1000 -

100

_.standard Sample 1 .,._Standard Sample 2 _..standard Sample 3 -standard Sample 4 .....-Standard Sample 5 --standard Sample 6 --Standard Sample 7

0.1

1000

100 " _.Core A Sample 1 -11-Core A Sample 2 ....-Core A Sample 3 -Core A Sample 4 -+-Core A Sample 5 ,.._Core A Sample 6 <0 a: -Core A Sample 7 --Core A Sample 8 0 Core A Sample 9 -+-CoreA Sample 10 ~ ';{ 10 ' ~

0.1 1000

100

_.Core B Sample 1 .,._Core B Sample 2 <0 a: -+-Core B Sample 3 -eore B Sample 4 0 -+-Core B Sample 5 --Core B Sample 6 ~ 10 -Core B Sample 7 -Core B Sample 8 ~ Core B Sample 9 -+-Core B Sample 10 8

Figure 4.9 - N-MORB-normalised multi-element diagrams for the unaltered and altered dolerites samples using normalisation values from Sun and McDonough (1989).

87 Table 4.2 -Sum of the trace elements for the Standard Core, Core A and Core B.

Core Set: Standard Core Sample No. 1 2 3 4 5 6 7 ll"race Elements 1900 1667 1624 1686 1847 1800 2242 Core Set: Core A Sample No. 1 2 3 4 5 6 7 8 9 10 ~race Elements 1538 1530 1871 2113 2074 2493 2270 2260 2358 2383 Core set: Core B Sample No. 1 2 3 4 5 6 7 8 9 10 ll"race Elements 1663 1634 1474 2312 2162 2132 1881 1977 1939 1818

The elements Cs, Rb, Pb, and Sr, display positive anomalies in Core A and B

compared to the Standard Core samples in Figure 4.9, an observation which is more

evident in multi-element diagrams for Core A and Core B that are normalised to the

average of the standards (Figure 4.10). Furthermore, Au has a very low

concentration in both Core A and B relative to the standards.

10

~ a. ..E "'~ 8 'E.. 'C c: b'l 0 &'. l!! ,.._CORE A Sample 1 -ti-CORE A Sample 2 £ --CORE A Sample 3 -CORE A Sample 4 -c( -;-CORE A Sample 5 -+-CORE A Sample 6 ~ ·--CORE A Sample 7 --·CORE A Sample 8 8 CORE A Sample 9 ·+-CORE A Sample 10

0.1

10

,.._CORE A Sample 1 -ti-CORE A Sample 2 --CORE A Sample 3 -coRE A sample 4 -+-CORE A Sample 5 -e-CORE A Sample 6 --CORE A sample 7 -CORE A Sample 8 CORE A sample 9 ....,..... CORE A Sample 10

0.1 Sc V Cr Co Ni Cu Zn Ga Rb Sr Y Zr Nb Mo Cs Ba Hf Ta W Pb Th U

Figure 4.10 - Multi-element diagrams for dolerite samples from Core A and Core B normalised to the average values from the Standard Core.

88 Enrichment-depletion diagrams are used to show relative enrichment and depletion in trace elements between samples (Figure 4.11 and Figure 4.12). They are normalised to the average values from the Standard Core and therefore display the extent of concentration increase or decrease of the elements relative to the

Standard Core.

....a.i 0 u -c.... ro -c c: .....ro V'l n Wl ,\(] ro

!.L .-1 IS .-1 .. .,:f d .... J3 Q) tlO OH ...ro I() Q) > / Q! ro Q) ' P!'l .s= +-' 03 0 +-' ws -c Q) PN .!!! Jd ro il) E... 0 Ill c: es S) Q) 0."' Olfol E qN ro JZ "'Q) +-' A ·;: .!!:! JS 0 ' ql:t -c co I!!) ...Q) uz 0 OJ u... 0 IN '+- 0) E ro J) ... tlO .!!:! JS" -c c: d 0 :;; ~ Q) eN 0. Q) I!) -c I lllfol +-'c: Q) Ulfol E .s= u ·;: c: UJ

Of particular note is the relative enrichment of many trace elements in samples 9 and 10 of Core A. These samples correlate with the heavily altered dolerite fragments extracted from the breccia in Core A. They include fragments from Sample

A14-a and Sample A14-b (Chapter 3.2). These samples are located very deep within

90 the brecciated core sequences (approximately 180m below surface), closer to where the source of the brecciation is thought to be located (Chapter 3).The element enrichment-depletion diagrams in Figure 4.11 and Figure 4.12 show that that there are a number of elements which show little change in concentration relative to the standards and others show progressive enrichment or depletion with sample number. lsocon diagrams may be used to quantitatively estimate change in mass or concentrations by plotting an altered composition against an original unaltered composition (Grant, 2005). Species that have remained immobile during alteration define the isocon, a straight line through the origin, with mass and concentration change due to alteration reflected as deviation of an indicated components data from this line. The isocon diagrams prepared in this study follow derivations of the calculations and methodology presented by Grant (1986; 2005). A statistical approach was used to determine the least mobile elements to base isocons on. An average of the concentrations of each element in the Standard Core samples was calculated and is used to represent the original or general composition of the dolerites (as in line with previous diagrams). The standard deviation of each element between samples of dolerite from the each of the brecciated core sequences was calculated. By implementing a limit of 0.5 standard deviation, trace elements Hf, Ta,

Tb, U, Ho, Tm, Tm, Yb and Lu are seen to remain mostly immobile and do not show any significant concentration differences between individual samples - this was confirmed by calculating the actual difference in concentration between individual samples, which was seen to be in the order of 1 ppm. These 9 trace elements were used to define the isocons.

All REE (which have been previously dealt with) except those used to define the isocons, were omitted from the isocon diagrams. Scaling of data for the remaining elements does neither affect the choice of immobile species, nor the slope of the isocon (op.cit.). Scaling factors applied to each component individually, are indicated in Table 4.3. The isocons generated for this study are considered to reflect acceptable estimations of actual mass changes. In each of the isocon diagrams in

Figures 4.13 and 4.14, the solid isocon is based on the immobile trace elements in

91 the specific sample as discussed earlier and the dashed isocon is based on immobile trace elements of the least altered dolerite sample in the sequence (Sample 1 in

Core A and B).

Table 4.3 -Scaling factors (S.F) used in construction of isocon diagrams.

Element S.F Element S.F Element S.F Element S.F

Si02 0.7 PzOs 52.74 Nb 3.57 Tb 8.55

Ti02 10.64 Cr 0.05 Rb 0.82 Ho 16.49

Al 2 0 3 1.86 Ni 0.22 Sr 0.08 Tm 12.11

Fe 2 0 3 2.65 Sc 0.8 Ta 33.6 Yb 3.83 MnO 75.83 Ba 0.08 Th 10.37 Lu 7.87 MgO 4.83 Co 0.55 u 8.75 Mo 18 CaO 2.96 Cs 4.67 v 0.11 Cu 0.17 NazO 6.8 Ga 1.78 Zr 0.29 Pb 0.56

K2 0 35.81 Hf 8.9 y 0.85 Zn 0.14

In Figure 4.13 it is seen that Core A Samples 1 to 3 show little relative mass gain or loss, and that the two isocons align well. The same can be said for Core B Samples 1 and 2 in Figure 4.14; in each case this indicates little alteration of these samples and variations from the isocons can being attributable to deuteric alteration.

As one examines the isocon diagrams for each Core A and Core B sample (Figure 4.13 and 4.14) in a sequential manner, component concentration variation becomes more apparent with each subsequent sample, as does the separation between the two isocons; these observations imply that there is a change between the concentrations of the elements in each sample relative to the least altered sample and the standards. An exception to the above statement is Core B Sample 10, which resembles the least altered Core B Sample 1 (discussed further in Chapter 6.3.5), which also shows a gain in CaO which can be attributed to the extensive calcite veining in the sample (Sample B15-b; Appendix B). Elements which often show increased concentrations relative to the isocons include Ab03, Ni, Cr, Sr, Sc, Cs, Co and Ba. Elements which tend to show decreased concentrations relative to the isocons include Si02, Fe 20 3, MgO, and K20. Elements which vary considerably in concentration between individual samples and relative to the isocons include CaO,

Zn, Sr and Rb. The observations as outlined above are in line with those as determined from the multi-element diagrams discussed previously and indicate sericitic and chloritic alteration accompanied by increased conscentations of base metals and the slight increase in REE (Figures 4.11 and 4.12).

92 40 .Po Sco v.i• 35 Sro Al,lj', "}'' ,' 5102 30 c i_i •!t; ..,25 '1.'11' }MilO N .. .. • • Zn Na,o~/ ~:0,r,o, 120 1 J J • Hj•,,' c c •1(20 c Cs c 'i TIO 5 15 M~Haosr • ,'' § M~ II" No,O y.li ,,' u 1o":"b § § Ma. ' 'f. 10 'f. 'f. AC 'f. 'tr ,ci:"cr T .,'' 20s

5 IIRb

0 40 Sc s,. Sr• Cr • 0 5~2,', caoo !ii ~ 1/ 35 •.v' it' .• Hf,'' 5102 Al,\1, Sc G:-' Al20.,pa . ..,,/ 30 Cd' •;; .0 ,' Nl0 co0 ~,'v Tho ~}",Q"zr , ,il0 y• , , 'F~,~f02 25 rt,b'(, ""110 , ·- 2 , .. 00 , , ,' ._ ,je,o, Ht .. , ea,tJ' MQO , t ,,' \..10 "1.• , j20 Fe,, , ~" _____,.,.h ,,' HO. 1 __,,-'" ri(,O 1 ,' .,.,o c \,o c c 'Na20 5 15 !j Nl• ~ T TiO ,'' u ! ,j!j'o oMIO § ' IICr ~ Y~ ,'•cr M"IO 'f. ~no, 'f. 'f. 10 ,o, 'f. Mea D20s IIR.b Tb/" ._ oMnO ~b M~OoRb ~ il\o"'o' u 0 u 0 5 ro u 20 25 30 ~ 401 o 10 15 20 25 30 35 40 CO-..., of Stllndords CO-..., of Stllndards 40 , c.,_NiiAI,Q~ / V, IIZr ' CuoNI!' ~~o r¥ IIZr Rbo .,. /~ ' Rt. Al201 r1t , ' 35 Hf. rtfe20;,, oTh Hf" fe,O,, , ' p2~~ . I(~,,' P,\ls k;~,' Figure 4.13 - lsocon diagrams for Core A Samples dolerite samples. 30 , , , olla,', 0 , , 510, z'lo .. 25 Ga• •5102 C represents the average concentration of elements from standard , , Goo • la ,'', , , Mq, , t , Nl, , dolerite samples, whilst CA represents those of the sample from 20 Nl, , 1 , , ' c , Core A as indicated on each diagrams vertical axis. The solid isocon , ~110 ic •Mao , , ,'• .Sr is based on immobile trace elements in the specific sample; the u' 15 'Y~/' Nl,o osr § ,'' Na20 t 10 'f. , ' , , dashed isocon is based on immobile trace elements of the least 'iT~/' CoO. , oeao , , altered dolerite sample from Core A (Sample 1} 1.0 w 0 10 15 20 25 30 35 40 0 5 ro u 20 25 30 ~ 40 COAwnop of Stllndords COAwrop of Stllndords ~ MICj, •MilO ~02 ,ji0 n 2

~ "zr ,' •1<20 s~o;,' Fe~3,,' Clio T~ n c'lo Hf~~o/' ~. N ... ,' .. , ~ t , Na 0T N •Th ,' j~ j 2 ,,' j j 2 H\ ," \a 0 ,' . • • . MnO ,jb ,' ;u T•'o • , ~..J3o ,' N\, ~ ~Tio,'•MilO u j 5 j Ybll .._, u ,' Rb •,,Cr ~ro ~ ~ ~ 0 2, > , , 5

0 ® sf' n lio Na~O

~ COli ,(_, S~z, , II' ,,' F.fz03 ,,'' •Hf ,' • , ,.slo2 . F~O)',510 2 ,. ,,'' .n ,H!,' ...... Mn'). • b "-O ,' ~ ,,'-zO ~ . ~ HO.fl.b~,/j ,-' ~0 j~ 1 j ,,'' • • ,:·?-'' • i.. ;u j r, V ,,"'' IICaO u j j P.. O:-/" • , ~ ,~6" 'Cr ~ro ,110 •MilO ~ ~

5 Ca'6

0 0 ro u w n ~ n ~~ o 1o1s20n~35~ ~ COAveraae of Standards COA.....,p of Standards •Fe203 Sc• c,p n

Figure 4.14- lsocon diagrams for Core B Samples dolerite samples. ~ S~C:z,' 0 C represents the average concentration of elements from standard .. 25 ~;,/ s t 2 dolerite samples. c!' represents the concentrations of elements in jW ,,'',', •K 0 the sample from Core Bas indicated on each diagrams vertical axis. . i j 15 Nl• ,,'', .CeO • is j The solid isocon based on immobile trace elements in the specific ~ 10 ,,•cr ~ sample; the dashed isocon is based on immobile trace elements of lll!b , .--Mo • the least altered dolerite sample from Core B (Sample 1) 5 ,' MnO 1.0 .j:::o 0 0 101s20n~35~ 0 10UW25~35~ COAverap of Standards COAvet'llp: of standards 4.3 Bulk rock geochemistry of fresh sedimentary rocks and the breccia matrix.

4.3.1 Classification and tectonic setting

A summary of the major element bulk rock geochemistry of the sedimentary samples is provided (Table 4.4). The complete set of geochemical data (major, trace and rare earth element) is provided in Appendix E.

Table 4.4 - Major element data of standard sedimentary rock samples and clast-supporting breccia matrix samples from Core A and Core B. Ca represents total Ca% of the sample. The complete geochemical data set can be found in Appendix E. rear; Set: Standard Core___ _ rsample No. 1 2 3 ~ I SiOz 81.26 83.80 77.50 Ti0 2 0.08 0.21 0.49 I Al 2 0 3 8.11 8.17 11.75 I r Fe 2 03 1.30 0.98 1.69 MnO 0.53 0.24 0.31 MgO 0.01 0.02 0.02 CaO 0.72 0.77 0.22

Na 20 1.34 1.14 1.99 I

'i KzO 4.95 3.15 3.76 I P2 0 5 0.02 0.11 0.07 I ~ 1.60 1.30 2.00 .---j jf~::P~=t~~~re A ___1______2____ 3 ____4 ____5_l

·, Si0 2 62.01 68.89 76.58 74.65 72.21 [

1 Ti0 2 0.54 0.38 0.27 0.39 0.50

] Al 2 0 3 10.62 9.53 7.34 9.32 10.341

1 Fe 203 6.82 3.77 1.76 3.21 4.06

I MnO 3.09 1.02 0.49 0.84 1.17 I

MgO 0.19 0.06 0.05 0.04 0.04 I CaO 5.06 4.98 4.47 2.32 2.08 ,

Na 2 0 1.18 1.09 0.95 0.68 0.87

, K20 2.04 3.21 3.09 2.87 2.82 I ' P2 0 5 0.20 0.06 0.03 0.16 0.07 LOI 8.10 6.80 4.80 5.40 5.60 I ------Core Set: Core B Sample No. 1 2 3 4 5 I Si0 2 81.72 72.88 72.72 56.68 74.87 I

Ti02 0.35 0.55 0.38 0.84 0.49 I

Al 2 0 3 4.79 12.34 11.50 13.26 10.42 Fez03 0.92 2.76 3.09 8.61 3.88 MnO 0.33 1.12 1.43 3.54 1.50 MgO 0.11 0.03 0.05 0.10 0.04 CaO 4.82 0.97 2.04 4.68 1.73

Na 20 0.39 0.92 2.03 3.32 1.29 KzO 1.66 2.77 3.24 1.73 2.65 PzOs 0.02 0.10 0.04 0.09 0.04 I LOI ______4_.8_0 ___5_.4_0 ___ 3._30 _____ 6_.9_0 ____2.~

95 The fresh sedimentary standards and the clast-supporting breccia matrix samples, can be classified as arkoses according to the classification diagram after Pettijohn et a/. (1972; 1975) (Figure 4.15); some samples straddle the litharenite and subarkose fields. A drawback of this diagram is that the Na 2 0/K2 0 ratio does not have the ability to distinguish between lithic arenites and feldspathic arenites (Herron, 1988).

•standards +Core A Breccia 1J. Core B Brecdo

~ o, 0 ! J Quartz arenite

-1 0 0.5 1 1.5 2.5 lo1 {SIOJAI2 0 1) Figure 4.15- Sedimentary rock classification diagram after Pettijohn et al. (1972).

The more recent "Herron" diagram (Herron, 1988) (Figure 4.16) shows that the standards can be classified as arenites. This is in line with the high percentage of quartz relative to other minerals in these samples. The breccia matrix samples tend more toward the litharenite and wacke fields. This is consistent with the observation that the breccia matrix contains a high percentage of lithic clasts and more fine grained material relative to the standards. Furthermore the standards have little calcite cement due to their low calcium concentrations (see Table 4.2), whereas the breccias are calcite cemented with calcium concentrations of above 1 wt% (Herron,

1988). This is consistent with petrographical observations.

i Shale J 0 .

-1. 0 0.5 I 1.5 IOI(SIOJAI2o.J Figure 4.16- Sedimentary rock classification diagram after Herron (1988).

96 A scheme devised by Bhatia and Crook (1986) is used to infer the tectonic setting of the fresh sedimentary rocks. The scheme uses immobile trace elements La, Th, Sc, Zr,

Y and Co. In the discriminating plots (Figure 4.17) of Bhatia and Crook (1986), the standard samples plot in the passive margin fields, i.e., these Ecca Group sediments, were deposited in a deltaic environment along the rim of the large, dominantly marine Karoo sedimentary basin (see Chapter 1.4.1), similar to the depositional setting of sequences deposited along passive margins which lead into open ocean.

La

• Standard Core • CoreA 1t. Core B (a) (b) / I / D i (.I c f'/. 1·~ (. ··-·-r B \, A A Sc Zr/10

A: Oceanic Island arc C: Active continental margin B: Continental island arc D: Passive margin

Th Figure 4.17- (a) La-Th-Sc and (b) Th-Co-Zr/10 ternary plots, showing the discriminating fields for the for the standard sedimentary rock and breccia matrix samples: A, oceanic island arc; B, continental island arc; C, active continental margin; D, passive margin (modified after Bhatia and Crook, 1986). See text for the interpretation of these geochemical signatures.

4.3.2 Comparison of geochemical characteristics of fresh sedimentary rocks and the breccia matrix

The standard samples show little chemical variation (Figure 4.18) and lower loss on ignition (LOI) relative to breccia matrix samples, i.e. between 1.3 - 2 wt% whilst the clast-supporting breccia matrix from both brecciated core sequences show LOI between 2.9 -8.1 wt%. (Table 4.4). The chemistry of the breccia matrix samples show more variation and have slightly higher concentrations of Fer (0.92 - 8.61 wt%) and CaO (0.97 - 5.06 wt%) and lower concentrations of Si0 2 (56.68 - 81.72 wt%),

Na 20 (0.39- 3.32) and K20 (1.66- 3.24 wt%) relative to the standard samples. These major elements have been reported to be commonly mobile under hydrothermal conditions in sedimentary rocks (Rollinson, 1993).

97 1.0 • Standard Core 14 • CoreA 12 o.s A ACoreB t • • • +Ia• 10 •• 8 AlzOs • l'.~a • • 6 (wt%) • &+ A 4 0.2 • • 2 0.0 • 0 10 0.20 9 A • 8 0.16 7 FeT 6 • o.12MaO 5 (wt%) (wt%) 0.08

• I • 0.04 ~o.• •••

3.5

3.0

2.5 A. • eao 2.0Na20 (wt%) 1.5 (wt%) & •• • • 4l • 1.0 • 0.5 0.0

6 0.4

5 • 0.3 4 KzO 3 r • • (wt%) 2 ; A • • • •& • • 0.1 & •• 0 JIL~ 0.0 55 65 75 85 55 65 75 85 Si02 lwt%l Si02 lwt%l

Figure 4.18- Plots of major elements vs. Si0 2 for the standard sedimentary rocks and breccia matrix samples.

The trace elements Cs, Sr, Rb, Ba, Cu, Zn, Pb and Cr (Figure 4.19) are expected to be mobile under ordinary sedimentary processes such as diagenesis and erosion

(Rollinson, 1993) - Pb shows the least variation in the breccia matrix samples when compared with the variation of Pb in the standards which cover a similar range.

Further examination of the trace element data beyond the commonly mobile elements show that there are an additional four trace elements, which display significant variation in the breccia matrix samples (Figure 4.20), with the remaining

98 8 350 • Standard Core 7 • CoreA 300 6 ACoreB • • 5 Cs ... 250 4 Sr (ppm) A • 3 ••• 200(ppm) .. ... • • • 150 0

140 120 • • • 1000.0 100 A • 800.0 Rb so • • ••• 600.0 Ba (ppm) (ppm) 60 A A + "" 400.0 40

20 200.0

______()______------+-·------______- __--- __-_·_·· __ - ___--·_"_-_- __--_- _·_- ______o~_.o:.. ______45 80 40 A 70

35 ' 60 30 • 50 Cu 2s • 40 Zn (ppm) 20 • • 1 30 (ppm) 15 • 10 • • ' 20 5 + A • • 10 • ..#1 •• .. 0 0

12 120 A + 10 A • 100

8 A 80 Pb , • Cr 6 • • 60 (ppm) A+ 40 (ppm) 4 ' A A 2 • • •• 20 • A • • • 0 -:---~---,---~---~---~·--·----·~-T-- 55 65 75 85 55 65 75 85 Si~lwt"l Si01 (~1

Figure 4.19 - Plots of selected trace elements vs. Si02 for standard sedimentary rocks and breccia matrix samples.

trace elements showing minor or insignificant variation relative to the fresh standard

samples. These four include Co, Ni, Sc and V. The Co and Ni increase can be

explained by the increase in organic content of the breccias (as macerated carbonaceous material) relative to the standards, with organic matter having an

affinity for these elements (Horowitz, 1991). The Sc and V cannot be explained in the

same way or by diagenetic or weathering processes, although the addition of

99 numerous lithologies to the breccia matrix which may contain varying amounts of these elements can explain their behaviour.

20 • Standard Core 80 A 18 +CoreA A 70 16 .A.CoreB 60 14 12 so Co • • 10 40 Ni (ppm) 8 • A A. A 30 (ppm) 6 . J:. • 20 4 : • \ • .t• • • 10 ------. 0 • .. IIIII . 0 ------~------30 180 J:. 160 25 A 140 20 120 100 Sc 15 v 80 (ppm) 60 (ppm) 10 • • • .. • •• At 40 5 •• • .. •• ~ 20 ... 0 0 • 55 65 75 85 55 65 75 85

Si02 (wt%} Si02 (wt%} Figure 4.20- Additional trace element variation diagrams of for the selected trace elements for the standard sedimentary rocks and breccia matrix samples.

The wide range in element concentrations in the breccia matrix samples cannot by attributed solely to diagenesis and weathering. In fact, the Sr/Rb ratios (Figure 4.21) indicate that Sr-rich feldspars in the original sediment have undergone relatively little degradation into (normally Rb-rich) clay minerals, a feature of immature and ill­ sorted sediments (Yigitbas et a/., 2008). Thus they must reflect changes attributed to the addition of lithic clasts with varying concentrations of different components.

(a) 5oo • Standard Core (b) 5.0

450 +CoreA 4.5

400 .A. Core 8 4.0 Mature 350 3.5

e- 300 ~ 3.0 1 • ! 250 !. 2.5 1 0 ~ 200 f 2.o I 150 Immature 1.5 I ...... 100 • 1.0 I .6. •• • 50 '···A A :: .... 100 200 300 400 r~--~" 500 Sr (ppm) cao (wt%) Figure 4.21 - (a) Rb-Sr diagram illustrating the maturity of the standard sedimentary rocks and breccia matrix samples (Yigitbas eta/., 2008); (b) MgO-CaO plot indicating their elevated concentrations relative to the standards.

100 The presence of minerals such as biotite, glauconite, zircon and garnet in the rocks

original composition may have an erratic effect on the REE (Rollinson, 1993) which

can explain the variations present within the standards relative to each other as seen

in Figure 4.22.

--Standard Core Sample 1 --Standard Core sample 2 --Standard Core sample 3

0.1

1 --CoreAsamplel ...-coreAsample2

1 Core A sample 3 -core Asample4 ! _,_eoreAsampleS 1 i---·-~···-~~·-·····-·····~--·····~·----··r::;;;o--...... ~::-r- ...... __ ~-

-. C(., 8

0.1

10 --Core B sample 1 --Core B Sample 2 ·--core B sample 3 -.-Core B sample 4 _,_Core B Sample 5

-.i "'., 8

lJI ce

Figure 4.22 - REE patterns of the standard sedimentary rocks and breccia matrix samples normalised to Post-Achean Australian Shale (PAAS) as per Taylor and Mclennan (1985).

101 By normalising the concentrations of the REE in the breccia matrix samples to the average concentrations of the REE in the standard samples (Figure 4.23), it is seen that the breccia matrix samples have increased amounts of REE. This observation can be explained by the variety of lithologies present in the breccia matrix samples (i.e. an increased amount of various REE-contain lithologies) and/or possible alteration.

-core A Sample 1 ...,._Core A Sample 2 _..,._Core A Sample 3 -core A Sample4 -core A Samples "' "'E 2 .....Ill <: Ill ~ -0 "' ~-~-i--~---·---,~----''l~?'r--·--"'-·----,~ ~ ~ ~ r----T"-"-"1;::~~'"4'...... ,_~ § _____,. ______~ :_M-'l!f, .... "'> .._< < 8"'

0.2

Pr Nd Sm Eu Gd Tb Dv Ho Er Tm Yb Lu y

Figure 4.23 - REE patterns of the sediments and breccia matrix samples normalised to the average of the standard samples.

Multi-element diagrams of the three sample sets are given in Figure 4.24. Elements

Cu, Cs, Lu and Pb have decreased concentrations in the breccia matrix samples relative to the Post-Archaean Australian Shale (PAAS) (Taylor and Mclennan, 1985).

102 Multi-element diagrams for Core A and Core B, normalised to the average of the standards for all trace element data available, reveal that Sc, V, Cr, Co, Ni, Cu, Zn, and Cs have relatively high concentrations in the brecciated samples relative to the standard samples (Figure 4.25).

10 ~Standard Core Sample 1 ___.Standard Core Sample 2 Standard Core Sample 3

1 ' .....~ 1!:' 0 u "E "0 "'c: v;"' 0.1

0.01

10 --Core A Sample 1 ---Core A Sample 2 """1!11·· Core A sample 3 -Core A Sample 4 -Core A Sample 5

0.1 I

0.01

10 --+-Core B Sample 1 ---Core 8 Sample 2 -'%;·~--Core 8 Sample 3 -Core 8 Sample 4 -core B Sample 5

0.1

0.01

Figure 4.24- Multi-element diagrams for the standard sedimentary rocks and breccia matrix samples normalised to Post-Archean Australian Shale (PAAS} as per Taylor and Mclennan (1985}.

103 -+-Core A Sample 1 -11-Core A Sample 2 10 ·'11\·" Core A Sample 3 -core A Sample 4 -+-Core A Sample 5

II) "'C ~ Ill "'C r::: Ill V) 0 ~ 1 I!! Cll ~

0.1 -+-Core B Sample 1 -11-Core B Sample 2 II) "E ·~·Core B Sample 3 -core B Sample 4 Ill "'C -+-Core B Sample 5 r::: Ill V) 0 ~ 10 I!! Cll >

0.1 Sc V Cr Co Ni Cu Zn Ga Rb Sr Y Zr Nb Mo Cs Ba Hf Ta

Figure 4.25 - Multi-element diagrams for breccia matrix samples from Core A and Core B normalised to the average values from the Standard Core.

Enrichment-depletion diagrams (Figure 4.26 and Figure 4.27) which show the relative enrichment and depletion in trace elements confirm that addition of components is dominant over their removal. This observation can be explained by presence of varying lithologies in the breccia samples, which may have either a dilution or concentrating effect on certain elements depending of the abundance of any particular lithology in the sample.

104 SO'[

"T1 06' c:., Core A/ Average of Standards 11) !=' g ~ ...... !:: N 0'1 I m .,::I r:;· '::t' 3 11) ::I .-+ c.I 11) "C ii) .-+o· ::I c. iii' Otl., Ql 3 -.,0 n 0., 11) )> .,t:r 11) n n iii' 3 Ql .,.-+ x· VI Ql 3 "C ii) ,VI ::I 0., 3 Cs Ql Ba iii' La 11) c. Ce .-+ 0 Pr .-+ Nd '::t' 11) Sm Ql < .,11) Ql Otl 11) < cQl 11) .,VI -0 Yb 3 Lu .-+ '::t' HI 11) I VI .-+ Ql ::I c. .,Ql c. • • ill • • n ~gggg 0 f'D f'D rD (1) f'D ., )>)>)>)>)> !D Bi I "'fft""QJ Ill a; ""c..n0.1 Q.l Th 3 3 3 3 3 "C"C"C"C"C u n;"'(i"(i'(i'(i" U'1~W.-..J~ o:"""'4NC"'''l-.;:tll"' QJ Q) Q) Q) Q) Q.Q.Q.Q.Q. Ero Ero Ero Era Ero \/') V"'' \/') \l'l V"'' n alalalalal 41 cv QJ Q) 11.1 Q) IS qj.... 88888 0 •••• u "'C.... 10 n\1 "'C 1:: M 10 e1 ~ Q.J .s::. +" E ....0 VI -Q.J ..a 10 > Q.J tlO ....10 Q.J > 10 Q.J .s::. +" 0 +" "'C Q.J ~ 10 E.... 0 1:: vi Q.J 0.. E 10 VI X ·;:: +" 10 E ·o10 u Q.J...... c co ....Q.J 0 u.... J2 E 10.... tlO .!!! "'C 1:: 0 :;:; ..9:! c.. Q.J "'C I +" 1:: Q.J E .s::. u ·;:: 1:: LLJ ...... N or:f ....Q.J ::::1 tlO ~

106 CHAPTER 5

STABLE ISOTOPES

5.1 Introduction

Stable isotopes show no observable tendency to change spontaneously (Allegre, 2008).

However, they can be fractionated by various naturally occurring chemical and physical processes, due to their differences in size and relative atomic weights, which cause them to react at different rates. The fractionation is calculated relative to a standard (o) and expressed as parts per million (permil; %o):

= [sample isotope ratio -standard isotope ratio ] * lOOO 6 (Allegre, 2008) standard isotope ratio

The study of stable isotopes allows investigation into the processes which separate the isotopes on a basis of their mass (Rollinson, 1993). Isotopes of carbon (o13C) are reported relative to the Pee Dee Belemnite (PDB) carbonate standard (a belemnite from the Cretaceous Peedee Formation (PDB) in South Carolina, USA) (Faure, 1986; Rollinson,

1993; White, 2009). Geochemists working with carbonates also report isotopes of oxygen (6180) relative to the PDB, whereas those working with substances other than carbonates report oxygen isotope ratios relative to Standard Mean Ocean Water

(SMOW) as defined by Craig (1961). PDB and SMOW can be linked by the following equation:

(De Groot, 2009)

In this study, the stable isotopes of both carbon and oxygen present in calcite veins in the brecciated core sequences were determined together with the same isotopes from calcite in an unaltered dolerite sample from the standard borehole core sequence. The objective was to identify and understand any anomalies between the brecciated cores and the standard, which may be linked to the deformational event. Carbon isotope data acquired is normalised to PDB and oxygen to SMOW and PDB. By definition, the

107 isotopes of these elements have 613C (relative to PDB) and 6180 (relative to PDB or

SMOW) values of zero in calcite (Rollinson, 1993).

5.2 Methodology

Ten samples of calcite, each weighting approximately 20 mg, were extracted from calcite veins present in the standard core and brecciated core sequences via the use standard corundum tipped hand drill. Approximately 8 - 10 mg of each sample was subjected to carbon and oxygen isotope analysis at the Department of Geological

Sciences, University of Cape Town. The method followed is based on that of McCrea

(1950). It involves the mass spectrometric analysis of the C02 gas liberated from carbonate after reaction with 100% phosphoric acid, accomplished using a MAT252

Mass Spectrometer. Carbon and oxygen isotope data are reported in standard 6 notation.

5.3 Stable isotope data

The samples include one standard sample, where calcite was extracted from a vein, cross-cutting a dolerite sample from the standard core sequence (STD-DOL 3-type dolerite; see Appendix C) at 35m depth below surface. The remainder of the samples were obtained from Core B at increasing depths from Samples B4, B6, B14-a, B14-b,

B15-a, and B15-b (Chapter 3.3). The data obtained from the different samples is reported in Table 5.1.

All of the calcite samples display depletion in 613C relative to PDB. The standard sample is less up to 12.73 %o depleted in 613C than samples from the brecciated sequences. The

13 6 Cp 08 value of the standard is -0.26 %o. Those from the brecciated sequences range between -4.88 %o and -12.99 %o. All samples are highly depleted in 6180 relative to

SMOW. The standard sample is less depleted in 6180 than samples from the brecciated sequences. The 6180sMow values are, to some extent, proportional relative to the

13 13 18 6 Cpos values for each sample, i.e. the more negative 6 Cp 08 is, the more negative 6 0

108 is (Figure 5.1). The 6180sMow value of the standard is -12.66 %o. Those from the brecciated sequences range between -13.6 %o and -20.95 %o.

Table 5.1 - Stable isotopic composition of calcite from the standard core and brecciated core sequences. Sample 613C PDB (%o) 6180 PDB (%o) 6180 SMOW (%o)

Standard Sample -0.26 -42.22 -12.66

Core A Calcite Sample -4.88 -43.13 -13.60

Core B Calcite Sample 1 -5.42 -48.22 -18.84

Core B Calcite Sample 2 -12.85 -49.70 -20.37

Core B Calcite Sample 3 -9.88 -50.26 -20.95

Core B Calcite Sample 4 -10.39 -50.08 -20.77

Core B Calcite Sample 5 -12.27 -49.76 -20.43

Core B Calcite Sample 6 -11.89 -49.29 -19.95

Core B Calcite Sample 7 -12.99 -49.63 -20.29

Core B Calcite Sample 8 -8.45 -47.05 -17.64

618QSMOW (o/oo) -25 -23 -21 -19 -17 -15 -13 -11

-2 • -4

-8

-10

-12

-14

18 Figure 5.1 - Scatter plots of 6 0sMow and 613Cpos for calcites from the standard core and brecciated core sequences.

109 There are a few possible explanations for negative 613C values (Figure 5.2). Fractionation of 613C is closely linked to the rock type and geological setting of the source area. For

13 example, carbonate rocks typically have negative 6 Cp08 signatures (Figure 5.2). 13 However, 6 Cp 08 signatures can typically be modified post depositional geological processes (Faure, 1986) and by interaction with dissolved organic carbon in ground water (Murphy et a/., 1989). McCrea {1950) observed that precipitation rates can also influence carbon fractionation, an effect further investigated by Romanek eta/. {1992).

With regards to the 6180 values, there are typically two main processes which could have produced changes in values: {1) re-equilibration of oxygen in constituent minerals from the temperature of crystallisation to the temperature at which the individual minerals close to oxygen diffusion; and {2) exchange with deuteric or external fluids

(Martinez et.a/., 1996). Oxygen fractionation by temperature can be significant as described further by White, {2009). However, pressure effects on fractionation factors are small and of little consequence (op.cit.).

The carbon and oxygen isotopes of calcites in the brecciated sequences show 613C and

6180 ranges fall into those normally present in fresh /meteoric water respectively

13 18 (Figure 5.2). The normal 6 Cpos and 6 0sMow ranges for the igneous and sedimentary rocks they occur in, lies between -3 to -8 and +5 to +13, respectively (Arthur eta/., 1983;

Hoefs, 1987 and Rollinson, 1993). It is possible that the 6180 results reflect the effect of modification in their original isotopic signatures due to the interference of meteoric waters. This is particularly true with regard to the 6180 ratio of the standard sample which falls within the meteoric range. The increased abundance of organic material in the brecciated core sequences, would explain the more negative 613C signatures present in calcites from these sequences, if meteoric water with dissolved organic carbon was circulating through these sediments.

The interaction of meteoric water with the calcites sampled, does not fully explain the

4.62 %o to 12.73 %o more negative 613C values, nor the 1.94 %o to 8.29 %o more negative

6180 Pos values {Table 5.1), between the calcite in the brecciated sequences, relative to

110 the standard. The possible causes for the atypically negative isotopic signatures of calcite from the brecciated cores relative to those in the standard core obtained in this study are discussed further in Chapter 7.3.6.

(a) Chondrite meteorites MORB • Carbonatites Diamonds Marbles Marine carbonate Marine bicarbonate + nonmarine organisms •••• Freshwater carbonates Limestones Se imentary organic carbon Biomass •I Atmospheric C02 ,-I Mantle Value -50 -40 -30 -20 -10 0 10 20 30 40 613C (o/oo)

(b) Chondrite meteorites I Bulk Earth MORB •I Andesites and rhyolites Granitoids Ba sa Itic rocks - Metmorphic rocks Detrital sediments - Argillic sediments - Limestone Ocean water ~ ••••••••••• Meteoric water Magmatic water • Metamorphic water ---- Mantle value 1 '--- --'----J ~ ~ ~ ~ -w o w m ~ ~ o18Q (%o)

Figure 5.2 - (a) 13C/2C ratios of some important carbon compounds {o13C relative to PDB); (b) 180/60 rations of some important oxygen containing compounds (6180 relative to SMOW). Data obtained from Arthur eta/. (1983), Hoefs {1987) and Rollinson (1993).

111 CHAPTER 6

DISCUSSION

6.1 A brief discussion on the possible origins of the brecciated core sequences

Interpretation into the cause of the brecciation present in the deformed borehole core sequences must take the following points into account:

• The sedimentary strata in the surrounding areas are structurally undisturbed and

the deformation is highly localised.

• The brecciated core sequences contain sedimentary clasts that are locally

derived from the Vryheid Formation and which were lithified prior to the

deformational event.

• The brecciated core sequences contain dolerite fragments which have been

affected by the deformational event.

A brief evaluation of the possible origin of the brecciated core sequences is provided in the following subsections.

6.1.1 Fault breccia

The presence of angular rock fragments within a relatively finer sandstone-dominated breccia matrix in the brecciated core sequences could be seen as evidence for faulting

(Fault breccia, 2011; Woodcock and Mort, 2008). However, there is no faulting present in any of the surrounding stratigraphy.

6.1.2 Sinkhole collapse

Sinkholes can result in the formation of breccia, when underlying limestone or dolomite is completely or partially dissolved by groundwater (Sinkhole, 2008; Newton, 1984;

1987; Van Den Eeckhaut eta/., 2007, Tharp, 1999), or by mining in karst areas (Gongyu and Wanfang, 1999). However, the study area is underlain by the stable Archean-aged cratonic granite basement (confirmed by the inspection of borehole logs) and

112 contemporary mining has not taking place within the immediate areas near the brecciated boreholes.

6.1.3 Meteorite impact

Breccias can be produced by the impact of a meteorite (French, 1998), however there are neither any known impact sites in close proximity to the brecciated boreholes, nor is there any petrographical evidence (French, 1998; Dressler and Reimold, 2004; Reimold and Gibson, 2005) to support this.

6.1.4 Syn-sedimentary deformation

Soft-sediment deformation is common in sedimentary basins (Oliveira et a/., 2011,

Owen et a/., 2011), occurring during or immediately after deposition. This is evidently not the case here, as the breccias contain post-depositional, younger dolerite fragments, in addition to lithified sedimentary clasts.

6.1.5 Diatreme activity

Intrusions such as sills and dykes can produce localised deformation, metamorphism, rock displacement and brecciation (Aarnes et a/., 2011; Brown et a/., 2007; De Oliveira and Cawthorn, 1999; Jamtveit et a/., 2004; Jamtveit, 2005; Planke eta/., 2005; Svensen et a/., 2006). Sandstone-breccia filled diatremes and hydrovolcanic pipes of the Karoo

Igneous Province have originated due to the explosive interaction between groundwater and hot magma, or due to fluid overpressures created in the host rocks during volcanism and sill emplacement (Duncan and Marsh, 2006; Jamtveit et a/., 2004; Svensen et a/., 2006). It has been shown that the formation of diatremes is closely related to the emplacement of sill intrusions (Pianke eta/., 2005).

The tremendous force involved in diatreme formation, can shatter and brecciate the rocks through which the diatreme occurs (Lorenz and Kurszlaukis, 2007), producing all of the features observed in the three boreholes in this study area. The mechanisms involved in diatreme formation can explain the geographically restricted states of the

113 brecciated core sequences, the angular, altered, and varying sizes of breccia fragments, as well as the presence of dolerite in the breccia.

There are a large number of known diatremes in the Karoo Basin (Du Toit, 1926; 1954;

Gevers, 1928; Dingle et a/., 1983), some of which have been described in detail (Roux,

1970), with working models having been proposed for their emplacement (Jamtveit et a/., 2004; Svensen eta/., 2006).

6.2 A review on diatremes

Large igneous provinces such as the Karoo Igneous Province are associated with the intrusion of extensive networks of sills and dykes (Duncan and Marsh, 2006; Eales eta/.,

1984; Erlank, 1984; Mountain, 1968; Walker and Poldervaart, 1949). Phreatic and phreatomagmatic volcanic activity are often associated with these events and can result in the formation of diatremes (Jamtveit eta/., 2004; Svensen eta/., 2006), which are also termed hydrothermal vent complexes or phreatomagmatic vent complexes.

Diatremes are cylindrical, funnel or carrot-shaped bodies with circular-to-elliptical cross sections and steeply dipping sides (Winter, 2001). They are filled with breccia which may comprise lithified sedimentary and/or igneous rocks (Jamtveit, 2004) consisting of angular or subangular rock fragments with a relatively finer matrix. The breccia may comprise sedimentary rocks with some igneous material (Svensen et a/., 2006), xenoliths (Mattsson et a/., 2005) and surface sediments (Rakovan, 2006; White and Ross, 2011). There are two models for the formation of diatremes: the phreatomagmatic model and the magmatic model (Lorenz and Kurszlaukis, 2007)

(Figure 6.1). In both models, diatremes are formed by a subterranean gaseous explosion which results in the formation of a breccia filled pipe-like structure containing a mixture of fragmented and broken rocks (op.cit).

The magmatic model suggests that the source of gaseous explosion which forms the diatreme is a result of degassing/devolitilisation of hot magma as it ascends toward the

114 surface along zones of weakness in the Earth's crust (Rakovan, 2006). At depth, the volatiles present in high concentrations in these magmas remain dissolved due to the confining pressure (Winter, 2001). As the magma approaches the surface, this confining pressure decreases to the point where the volatiles can no longer be dissolved. Thus the expansion of gases from the magma is imminent and a violent exsolution occurs

(Rakovan, 2006; Winter, 2001). The gases expand upwards due to their lower density, brecciating the surrounding rocks. The erupting gases and fluids rise extremely rapidly, often reaching speeds of up to a few hundred meters per second during their ascent

(Boorman et a/., 2003). The decrease in confining pressure towards the surface

promotes lateral expansion of the diatreme.

The phreatomagmatic model differs from the magmatic model in that the source of the

associated gasses and fluids are not derived from the magma per se. Instead the associated gasses and fluids originate from the flash boiling and gasification of water as

hot magma is introduced into a water/water-filled body. The water may be groundwater, pore fluids in sedimentary strata, meteoric water, or even an open water

body such as a river or lake (Lorenz and Kurszlaukis, 2007; Jamtveit eta/., 2004; Svensen

et a/., 2006). The subsequent flash-boiling produces gases which expand rapidly and

cause an explosion similar to the magmatic model, whereby brecciation and sediment fluidisation occurs (Svensen eta/., 2006).

There is a broad consensus that diatremes are formed according to the

phreatomagmatic model (Lorenz and Kurszlaukis, 2007) and contact metamorphism to the surrounding country rocks and breccia fragments occurs;

"Country rock fragments in diatremes are not commonly thermally metamorphosed

(except where contained in juvenile fragments); alteration is generally hydrous" (White and Ross, 2011).

A dyke or sill is the source of the hot magma which acts as the trigger or the feeding volcanism required for diatreme formation (Bradley, 1965; Lorenz and Kurszlaukis, 2007;

Planke et a/. 2005; Svensen eta/., 2006). Dykes and sills which feed volcanism are well

115 known from all volcanic environments and all magma types (Lorenz and Kurszlaukis,

2007). Diatremes may cut dykes or sills which are older than the diatreme and in turn dykes or sills which initiate diatreme formation may crosscut by the ensuing diatreme.

This is because after the formation of the diatreme, the dyke or sill may continue to develop. Diatremes may also form relatively close to the surface, due to the fact that dykes and sills can be emplaced at much higher levels than large magmatic intrusions

(Lorenz and Kurszlaukis, 2007).

(b)

Lower part

-300m

Figure 6.1 - Schematic diagrams of idealised diatremes. (a) A simple cross-section through a diatreme. The diagram represents the magmatic model, whereby the source of gaseous explosion which forms the diatreme is a result of degassing/devolitilisation of hot magma. (b) A representation of the phreatomagmatic model, where associated gasses and fluids originate from the flash boiling of groundwater, meteoric water, pore fluids or a water body by hot magma. The diagram illustrates the flash boiling of pore fluids as the cause for diatreme formation (Image from: Svensen et of., 2006).

Svensen eta/. (2006) summarised the structure and evolution of diatremes in the Karoo

Basin, in addition to documenting two diatremes present in the in the

116 Eastern Cape Province of South Africa. A phreatomagmatic model, which is similar to one that the authors previously proposed (Jamtveit et a/., 2004L is applicable to this work. In the model, the emplacement of sills leads to boiling of pore fluids, resulting in

high overpressures and an explosive rise of hot fluids and fluidised sediments towards the surface (op. cit.). The result is the diatreme breccia pipe.

6.3 Evidence to support a diatreme model

Evidence to support diatreme activity as the mode of formation of the brecciated core sequences is presented in an order which reflects the sequence of the methods employed in this investigation. Furthermore, it is shown that the phreatomagmatic model is the most applicable to this study.

6.3.1 The isolated occurrences of the brecciated borehole core sequences

A characteristic of diatremes is their highly localised nature and random occurrence, due to the fact that the related igneous intrusion will ascend toward the surface along any appropriate zone of weakness in the Earth's crust (Rakovan, 2006), often exploiting weaknesses between sedimentary beds {Winter, 2001). Consequently, a diatreme can occur at any point along the intrusive path where the conditions are favourable.

Although most dykes and sills are emplaced in a single event, some have a history of multiple injections (op.cit). The intrusions can be composite if more than one rock type is represented. De Olivera {1997) studied the morphology and nature of the intrusion of the dolerite dykes and sills located at the Majuba Colliery, less than 80 km south-east of the present study area. His work revealed at least four dolerite sills at Majuba, two of which some have dissimilar textures, geochemical signatures and modes of emplacement. A similar scenario is envisaged in the present study area. In this study three separate dolerite sills are inferred from samples obtained from the standard core, with two being similar. There is a possible fourth dolerite located sill at depth as inferred from the occurrence of dolerite stringers in some of the logs studied (see Chapter 3).

117 The implication of the existence of multiple intrusions is that the diatremes need not be linked to a single dolerite intrusion, a point which further supports their random occurrences.

6.3.2 The lithologies of the brecciated borehole core sequences

The brecciated borehole core sequences contain extremely angular sedimentary rock clasts with the same composition as the local strata constitute the Vryheid Formation.

Clasts and fragments vary from individual blocks of the sedimentary lithologies and dolerite, to finely macerated rock fragments and matrix material. Some sedimentary clasts display pristine primary sedimentary structures, albeit those clasts in which the structures occur are randomly orientated within the breccias. 'Dykelets' filled with a mixture of sandstone and finely brecciated material cross-cut some of the sequences.

The sedimentary lithologies were already lithified prior to the deformational event.

These are all typical characteristics of breccia formed through diatreme activity. The lithologies observed in the brecciated core sequences in this study closely resemble those of other known diatremes in the Karoo Basin, such as those described by Dingle et a/. (1983), Du Toit (1926; 1954), Duncan and Marsh (2006), Gevers (1928), Jamtveit

(2004), Raux (1970) and Svensen et a/. (2006). These are in addition to the common lithological characteristics of diatremes as described by Lorenz and Kurszlaukis (2007),

Rakovan (2006) and White and Ross (2011).

6.3.3 Sediment fluidisation

The intrusion of sediment into a host rock is somewhat of an unusual geological occurrence, although it has been documented in the past (Curtis and Riley, 2003), even on larger scales (Svensen et a/., 2010). The heat, high-pressure gradients and sediment mobilisation generated during diatreme formation (Jamtveit, 2004; Svensen eta/., 2006) can explain the occurrence of the small scale dyke-like intrusions of sediment­ dominated breccia, into lithified sedimentary rocks and clasts in the brecciated core sequences (Sample A6; Sample A12; and Sample A15-c). The breccia dykelets also occur within the igneous lithologies (Sample A3-b,) and in some cases within another breccia

118 (Sample B8-c; Sample B9-a), both at a macro- and microscopic scale (Sample A2; Sample

A3-b). The occurrence of the variety of sedimentary clasts and fragments of dolerite within a finer-grained breccia matrix, with grains and material derived from the same lithological units, would be difficult to explain without some form of fluid assisted movement.

6.3.4 Lithological variations with depth

Petrographical observations indicate that the intensity of brecciation in the anomalous core sequences increases with depth. For example, in Sample A3-b, the direction of movement of breccia and fluids through the dolerite is preserved and is surface-directed

(Figure A.3.ii, Appendix A). The intensity of fracture of the grains which constitute the matrix of the breccias also generally increases with depth as does the abundance of dolerite fragments within the brecciated core sequences. In Core B and Core C, brecciation in the core sequence is most intense just above the lowermost dolerite units present at the bottom of the sequences and in both cases these underlying dolerites are exceedingly veined.

The above observations imply that the source of the deformation was located beneath the brecciated sequences. This is consistent with a diatreme model, where a gaseous explosion cause by fluid vaporisation occurs at depth, with the blast being directed toward the surface. It is logical that the pressure, temperature and fluids level would be greater near the source, thus the intensity of deformation should increase with depth.

6.3.5 Mineral chemical and geochemical implications

Macroscopically, alteration is easily noticeable in the dolerite fragments which occur in both Core A and Core B. These fragments are extremely fine grained and vary in colour in Core A from light-pale green to yellow-orange and orange-brown and from light pale­ green to dark-green in Core B. The alteration is more evident under the microscope, as illustrated in Figure 3.10. The alteration minerals include sericite, chlorite, iddingsite, occasional goethite and possible hydroxides, unidentified clay minerals and mixtures of

119 the minerals in varying proportions. Furthermore, an increase in the volatile content of the altered dolerite samples was noted. Pyroxene is often present only as relict crystals and alteration characterised by a loss of Ca, which is also noted in altered plagioclase feldspar crystals.

The bulk rock geochemistry of the dolerites fragments extracted from the breccias shows that they do not reflect their original rock chemistry. The high loss on ignition

(LOI) and varying major and trace element compositions, in many cases, can be ' attributed to an increase in the volatile content of the samples as a result of chemical change resulting from the interaction with pressurised, hot volatiles and fluids during the formation of a diatreme. The alteration is generally characterised by a loss of Si02,

Fe20 3, MgO, and K20 and scattered CaO, Zn, Sr and Rb concentrations. The altered samples show increased concentrations of Al 20 3, Ni, Cr, Sr, Sc, Cs, Co and Ba. Mass losses in the altered samples can most likely be attributed to increased volatile content and to sericitic and chloritic alteration which are accompanied by increased concentrations of base metals and the slight increase in REE (as seen in Figures 4.9 and 4.10).

The geochemistry of the clast-supporting breccia matrix shows decreased Si02, K20 and Na20 concentrations, increased in MgO, Co, Ni, Sc and V concentrations and scattered

CaO concentrations relative to the standard sedimentary samples. In the case of the bulk geochemistry of the clast-supporting breccia matrix samples, all trends can be explained by the numerous new lithologies present compared with the sedimentary standards (see Chapter 4.3.2). The mechanisms involved in the formation of a diatreme as outlined in Section 6.2 easily explain occurrence or addition of many types of lithologies in the brecciated core sequences.

6.3.6 Stable isotope implications

The replacement of calcite by fine grained sediment-dominated breccia (e.g.

Sample A3-b), in dolerite fragments contained within the breccias, suggests that calcite

120 was present in the dolerite prior to the deformational event. There is also calcite present in the form of calcite veins and calcite cement in the clast-supporting breccia; dissimilarities are present between the 613C and 5180 isotopic signatures of calcite samples from the brecciated sequences versus those from the standard sample, i.e., these calcite samples from the brecciated sequences show much less negative 513C and 5180 isotope values (Table 5.1). The dissimilarities described above imply that these calcites are genetically related to the diatreme forming processes, as any other process would have had an equivalent effect on the standard sample; this also implies that the carbonates present in the brecciated sequences are of syn- or post-diatreme age.

Causes for the very negative isotopic signatures of calcite samples from the brecciated sequences relating the diatreme formation are discussed below.

Coal and organically derived material usually have very negative 613C values (Arther et a/., 1983; Hoefs, 1987; Faure, 1986) (Figure 5.2). Fluids reacting with the organic material during diatreme formation could have assimilated some of the negative carbon signatures from the organic material, resulting in more negative 613C values in precipitated ca Ieite.

There is little evidence to support the increased fractionation of oxygen due to pressure increases in geological systems (Clayton et a/., 1975). However, the temperature of 18 16 precipitation of CaC0 3 leads to marked variations in the 6 0 I 6 0 ratio, with the general trend indicating that increases in temperature produce more negative 6180 values (Arther et a/., 1983a; Faure, 1986; Hoefs, 1987). The more negative 5180 values present in the calcite samples from the brecciated sequences (relative to that those of the standard sample) can be attributed to the combination of higher temperatures of precipitation experienced within the diatreme (given that diatreme formation is fuelled by the intrusion of hot magma) and the interaction with meteoric water (Chapter 5.3).

121 6.3.7 Lithological implications towards a diatreme model

Magmatic diatremes are more likely to occur in volatile-rich systems with C0 2-rich (Lorenz and Kurszlaukis, 2007) and are very unlikely to be generated by relatively dry basaltic systems, such as the Karroo dolerites (Eales et al., 1984; Erlank,

1984).

Jamtveit et a/. (2004) showed that if the fluid pressure present during the cooling of a magmatic intrusion exceeds the lithostatic load pressure, the fluid flowing away from the heat source will be associated with fluid channelling (hydrothermal venting).

Calculations concerning the fluid pressure evolution around shallow sill intrusions show that overpressures generated from the boiling of pore fluids near the sill-sediment boundary, triggers diatreme activity (op.cit.). In accordance with this model, the conditions under which venting may or may not occur can be determined as a function of the depth of a sill intrusion and the permeability of the country rock.

The permeability of the Vryheid Formation rocks in the study area was estimated using data obtained from Venter and Jermy (1994). The results are given in Table 6.1, with maximum negative calculated Log (permeability) values of -19 and a maximum negative value of -14.50. Figure 6.2 shows under what depth and permeability's venting can occur and that venting can readily occur in the Vryheid Formation. The Vryheid

Formation is no thicker than 290m in the study area (as determined from borehole logs) and approximately 300 m in the Highveld coalfield in general (Snyman, 1998). Therefore diatreme formation is possible via the phreatomagmatic/fluid overpressure model.

Core B contains a possible sill located at the base of the sequence as reflected by

Sample B15-b (Figure 3.9), which in itself is brecciated. The sample is excessively veined with calcite, as is the similar dolerite sample above, Sample B15-a and little alteration is present (see Chapter 4.2.2, Figure 4.12 indicated as Core B Sample 10) relative to the unaltered dolerites. In this case, it is possible that this sill was the source and/or trigger

122 which lead to phreatomagmatic diatreme activity here. Furthermore, the sill itself is a possible source for the dolerite fragments found within the breccias.

2 1 Table 6.1 - Re-calculated permeability's (m s- ) of the sedimentary rocks of the Vryheid Formation using data obtained from Venter and Jermy (1994). Facies type Log (permeability) Minimum Maximum Average Lenticular bedded mudrock -17.24 -15.59 -15.92 Alternating layers of medium- and fine-grained sandstone -17.60 -15.21 -16.09 Flaser-bedded fine-grained sandstone 1-17.74 1-17.40 1-17.54 Ripple cross-laminated fine-grained sandstone 1-17.62 1-17.16 1-17.59 Massive fine-grained feldspathic sandstone 1-17.70 1-16.60 1-16.97 Cross-laminated fine-grained feldspathic sandstone 1-19.00 1-15.93 1 -16.55 Massive medium-grained feldspathic sandstone -16.67 -15.81 -15.55 Cross-laminated medium-grained feldspathic sandstone -16.90 -14.57 -15.36

Massive coarse-grained feldspathic sandstone 1-16.17 1 -14.67 1 -15.41 Cross-laminated coarse-grained feldspathic sandstone i -15.80 l-14.50 _I -14.98

Loc (permeability) -20 -19 -18 -17 -16 -15 -14 -13 -12 -11 0.0

0.2

-E 0.4 .X -.J: 0.6 ..a. cII 0.8 No venting

1.0

1.2 Figure 6.2- Depth of intrusion vs. permeability of country rock diagram, modified from Jamtveit eta/. (2004). The orange shaded region indicates the feasible region were venting may occur in the study area using permeability data obtained from Venter and Jermy (1994), in addition to the estimated maximum depth of the Vryheid Formation in the study area (as determined from borehole core logs).

123 CHAPTER 7

CONCLUSIONS

7.1 Motivation for a diatreme model

In Chapter 6.1, it is shown by a process of elimination, that the only viable mode of origin for the brecciated core sequences is that of diatreme activity. There is sufficient evidence to support this model as discussed in Chapter 6.3. Diatremes need not be associated with only one dolerite intrusion (see Chapter 6.3.1) and thus each brecciated borehole core sequences can be associated with multiple dolerite intrusions, allowing for their isolated occurrences (Chapter 2). The brecciated borehole core sequences contain lithologies, including juvenile magmatic components (Chapter 2 and 3), which are closely similar to those lithologies of other known diatremes (Chapter 6.3.2). The intense heat and pressure associated with the diatreme formation explains the presence of the small-scale dyke-like intrusions of sediment-dominated breccia (Chapter 6.3.3); this is evidence for sediment fluidisation, which is linked to the mechanism involved in the formation of the diatreme (Chapter 6.2). The increase with depth, in degree of brecciation and alteration, grain fracture and dolerite abundances in the brecciated borehole core sequences, are all consistent with a subterraneous origin for the deformation (dolerite intrusion) and the diatreme formation models (Chapter 6.2). The alteration of the lithologies of the brecciated core sequences, which is noted at both macro- and microscopic levels, (Chapters 3 and 4) can be explained by diatreme processes (Chapter 6.3.5). Discrepancies in the stable isotopic compositions of calcites present in the brecciated core sequences relative to calcites in the undisturbed core sequence can be explained by diatreme processes (Chapter 6.3.6).

124 7.2 Proposed model for the formation of the brecciated core sequences

There is little evidence to support the magmatic model of diatreme formation in this study (Chapter 6.3.7). Phreatomagmatic activity is possible in the Vryheid Formation, and has been documented elsewhere in the Karoo Basin (Svensen et a/., 2006). Under this model, heat from an intruding hot sill into the sedimentary rocks of the Vryheid

Formation in the study area, creates overpressures in the host rocks pore fluids, resulting in a gaseous underground explosion, which propagates upwards and creates a breccia filled pipe-like structure. The resulting diatreme has a very limited lateral extent, thus surrounding boreholes contain normal, undeformed strata.

7.3 Time constraints for diatreme formation

The lithologies of the brecciated borehole core sequences imply that diatreme formation post-dates the Karroo sedimentation. The geochemistry of the dolerite fragments occurring within the breccias, demonstrates that they are linked to the intrusion of sills in the area (see Chapter 4.2.2). The dolerite fragments are interpreted to be juvenile clasts sourced from the sills which initiated diatreme activity. The intrusion of dolerite sills and dykes into the Karroo Supergroup also post-dates the

Karoo sedimentation. These intrusions represent the feeders system of the Drakensberg

Group which has been dated to 183± 2Ma (see Chapter 1.4.2). The approximate age of diatreme formation is therefore constrained to the middle Jurassic period.

7.4 Conclusion

Diatreme activity is responsible for the occurrence of the three brecciated core sequences located within the study area. They are linked to the intrusion of Jurassic­ aged dolerite sills at depth in the region. This conclusion correlates with other known

125 diatremes in the greater Karoo Basin which are of similar and younger ages. Their formation post-dates the Permian-aged Karoo sedimentation.

7.5 Future studies and implications to mining activity

Although diatremes tend to occur rather randomly, an encouraging factor in this mode of formation is that diatremes are highly localised. The diatremes in this study are inferred to be no greater than 250 m in diameter (as determined by stratigraphic analyses; Chapter 2) and their true lateral extent is most likely even less. Thus diatremes pose no greater concern than that of the igneous intrusions which occur with far greater frequency throughout the greater Highveld coalfield.

A seismic approach has been seen to be useful in identifying large scale diatremes in the north-central V(ljring Basin on the mid-Norwegian margin (Jamtveit et a/.,2004), though the application to much smaller scale diatremes, as in this study, is untested. It may be possible to predict and delineate the extent of diatremes such as those found in this study via geophysical investigation.

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139 Appendix A - Full descriptions of the petrology and petrography of brecciated core sequence A

Note:

1. The core samples shown here correspond to all core samples from brecciated core

sequence A as referred to throughout the study.

2. Each sample is described in detail. In order to avoid unnecessary descriptive

repetition, the following aspects apply to the core sequences described here

(unless otherwise stated):

• Any and all breccia clasts found within the core sequences and fragments are

angular and randomly orientated.

• All grains which constitute the sandstones and sandstone breccias are angular to

sub-angular and have medium-to-low sphericity.

• All the sandstones and sandstone breccias are poorly sorted.

• All photomicrographs were taken using plane polarised light.

• All facies labels used correspond to those as indicated in Table 3.2 (p46).

140 Sample Reference Number: Al Sample name: Relatively unaltered dolerite Reference Figure: A.l

Macroscopic Description: This is light grey, aphanitic igneous rock (< 1 mm grain size), composed of pyroxene and pragioclase. The top of the sample is broken along the contact between the dolerite and a calcite vein, revealing a black contact rim and elongated crystals of calcite.

Microscopic Description: Dolerite shows typical igneous texture i.e. crystals are arranged in an irregular mesh, all of which show corroded rims. The dolerite consists of 80 % matrix and 20 % phenocrysts. Phenocrysts of plagioclase are common and pyroxene phenocrysts are also present. Plagioclase and pyroxene account for 60% and 40% of the volume of the rock respectively. Further details follow:

Matrix: Plagioclase occurs as lath-shaped, white to grey crystals, averaging 1 / 2 mm in size. They show both Carlsbad and albite twinning.

1 Pyroxene occurs as subhedral crystals averaging / 4 mm in size. Clinopyroxene (augite and pigeonite) is dominant. Orthopyroxene occurs sparingly as enstatite and ferrosilite throughout the sample and they are often intergrown with clinopyroxene. Most of the pyroxene crystals show little pleochroism, indicating more Mg-rich compositions.

Fine-grained interstitial plagioclase and pyroxene glass occurs between other crystals along with minor amounts of chlorite and oxide minerals.

Phenocrysts: Plagioclase occurs as lath-shaped, white to grey, randomly orientated, anhedral crystals, 1 mm to 3 mm in size. They show Carlsbad and albite twinning, with oscillatory zoning present in many of the crystals. Some crystals show strings of orthoclase.

Clinopyroxene phenocrysts are smaller in size (less than 1h mm) and fewer relative to the plagioclase phenocrysts. They are pale green or pale red-yellow in colour and bluish or pinkish when thick. The crystals are subhedral, and some show twinning in the form of a single twin-plane.

141 Figure A.l - Reference images for Sample Al. The relatively unaltered dolerite core sample is shown in (a). Photomicrographs show the typical igneous texture of the sample (b) and a typical plagioclase phenocryst showing jagged rims, twinning and orthoclase exsolution lamina (c).

142 Sample Reference Number: A2 Sample name: Breccia Reference Figure: A.2

Macroscopic Description: This core sequence contains rocks fragments and clasts (1h mm to 10 em in size) found within a fine sand-sized matrix. The matrix contains calcite cement and consists of clear and smoky quartz (dominant), biotite, muscovite and macerated carbonaceous siltstone fragments. Breccia fragments and clasts include:

• carbonaceous and micaceous laminated siltstone • dark grey siltstone • coarse-grained, massive sandstone which contains silty laminations • planar cross-bedded arkosic sandstone • bioturbated sandstone with abundant silty laminations • dark green-black, fine-grained brecciated dolerite with1mm wide cross­ cutting vein lets of calcite

Microscopic Description: The breccia contains grains of quartz, microcline, muscovite and carbonaceous materials. The larger grains are quartz grains eh mm) which show strain indicated by wavy extinction. There are some microcline grains up to 1 mm in diameter. All grains are cemented with calcite. Most grains show moderate to intense fracturing; the fractures are often filled with calcite.

The dolerite fragments in this sample are very fine-grained (minerals are less than 1 / 8 mm in length) with plagioclase having the largest crystal sizes. Plagioclase phenocrysts are also present and are 1 - 2 mm in length. Many microfractures less than 1h mm in width occur and are filled with calcite. The dolerite fragments display a 1 mm wide, dark-brown contact zone with breccia.

143 Figure A.2 - Reference images for Sample A2. The brecciated core sample is shown in (a). The photomicrographs show the contact between the breccia and a dolerite clast (b); dolerite (c); breccia (d); a siltstone clast in the breccia (e).

144 Sample Reference Number: A3-a Sample name: Altered dolerite Reference Figure: A.3.i

Macroscopic Description: The top 13 em of the sample is an orange-brown, altered, aphanitic dolerite. The lower 28 em of the sample is a grey, altered aphanitic dolerite. Both are composed of clinopyroxene and plagioclase. The contact between the two sections is sharp.

Microscopic Description: 1 1 The grey portion has small grain sizes ( / 8 mm to / 2 mm) and the grains show substantial corrosion and very jagged rims. It is composed of plagioclase and pyroxenes accounting for 60 % and 40 % of the dolerite respectively. It consists of 80 % of matrix minerals and 20% phenocrysts. More specifically:

1 Matrix: Plagioclase occurs as "' / 2 mm long, white to grey, lath-shaped crystals, showing Carlsbad and albite twinning.

Pyroxenes occur essentially as subhedral clinopyroxene crystals less than 1 / 4 mm in size with some preserving twinning.

Fine-grained interstitial plagioclase and pyroxene glass occurs between other crystals.

Phenocrysts: Plagioclase phenocrysts are 1 mm to 3 mm long, white to grey and lath­ shaped. They show Carlsbad, albite and oscillatory twinning and contain inclusions of pyroxene.

Clinopyroxene phenocrysts which are less than 1h mm in size occur, with subhedral crystals, a few of which preserving twinning and/or show gradual zoning.

The orange dolerite at the top of the sample has similar mineralogy and mineral proportions as the grey dolerite below. However, this section has been further altered. The pyroxene crystals are all altered to circular, fractured, orange-brown forms, and some have re-crystallised centres. Corrosion and alteration has resulted in breakdown of mineral forms and phenocrysts. This orange-brown section thus consists of 90 % matrix and 10 % phenocrysts. All fine-grained interstitial minerals are altered to an orange colour. The typical igneous texture (irregular mesh texture) is preserved.

145 Figure A.3.i - Reference images for Sample A3-a. The core sample is shown in (a). Photomicrographs (b) and (c) show the texture of the upper section with fractured and/or altered plagioclase and pyroxene phenocrysts respectively. The texture of the lower section is shown in photomicrographs (d) and (e).

146 Sample Reference Number: A3-b Sample name: Altered dolerite Reference Figure: A.3.ii

Macroscopic Description: This is a grey-green aphanitic, altered dolerite, composed of plagioclase, pyroxenes and minor amounts of secondary biotite. It contains crystals of calcite and small {1 mm wide) cross-cutting fractures filled with calcite. A large, steeply dipping, dark orange-brown vein-like portion with a black reaction rim cuts the dolerite. It is filled with brecciated and altered materials. The sample also contains a 1 em - thick piece of coarse-grained, calcite-rich sandstone breccia cutting through the lower half of the sample at an angle of approximately 45° to the horizontal. It is similar in composition to the matrix of the breccia discussed for Sample A2.

Microscopic Description: The dolerite has a green-orange colour and is composed of corroded and fractured plagioclase and pyroxene crystals. The pyroxene crystals are altered to an orange-brown colour. Plagioclase and pyroxene account for 60 % and 40 % of the volume of the rock respectively. Minor (1 mm} flecks of biotite are present. Ninety percent of the dolerite is 1 1 matrix, with the crystals having grain sizes / 8 mm to / 2 mm. The other 10% consists of highly fractured and altered phenocrysts of plagioclase and pyroxene.

The dark orange-brown vein-like portions consists of a mixture of breccia and altered dolerite, i.e. it contains plagioclase, altered pyroxene, quartz, muscovite, microcline and finer grained alteration products. The grains and crystals are highly fractured and 1 corroded at the edges. Grains sizes average less than / 4 mm. A preferred grain direction is visible in the breccia and its matrix. They grains are orientated toward the surface direction (see sample Figure 3.7}. When the breccia is in contact with a calcite vein in the dolerite, the breccia replaces part of the vein.

The 1 em-thick breccia vein-like portion is composed quartz (shows undulatory extinction), microcline (grey to white with polysynthetic twinning}, minor biotite, muscovite, calcite cement and fine-grained interstitial material with the same mineralogy. The largest grains are quartz eh mm) and some fracturing is visible in them.

147 Figure A.3.ii - Reference images for Sample A3-b. The core sample is shown in image (a). Photomicrographs show the typical texture and altered phenocrysts (b); typical breccia with alteration products in a breccia vein (c); calcite replacement by breccia (d) extending from a from a breccia vein (e).

148 Sample Reference Number: A4-a Sample name: Altered dolerite and breccia Reference Figure: A.4.i

Macroscopic Description: The top 24 em of this sample consists of light orange-brown, altered dolerite. It is aphanitic and is composed of plagioclase and pyroxene. Plagioclase crystals are frequently either partly or completely replaced by calcite. Calcite is also present in the groundmass. The sample contains 1 mm wide cross-cutting veins of calcite and sulphides including brass-coloured pyrite. The orange-brown alteration colour of the dolerite is strongest within 5 mm thick zones flanking the veins as well as near the contact with the breccia below the dolerite (here the dark orange zone is 10 mm wide). However, immediately before the sharp contact with the breccia, there is a 1 mm wide, leached, lighter orange-yellow zone.

The bottom 6 em of this sample consists of carbonaceous sandstone breccia. It has a dark-grey, fine-to-coarse grained matrix. It is composed of clear and smoky quartz, and macerated carbonaceous siltstone fragments. The breccia contains fragments and clasts including:

• lenticular-laminated carbonaceous siltstone • dull black, carbonaceous coaly siltstone • massive sandstone with minor siltstone laminations • orange-gold, oxidised sulphide minerals • orange, altered dolerite (as found above the breccia)

Microscopic Description: This dolerite is highly altered. The minerals are only identifiable by habit in thin section. Plagioclase phenocrysts (1- 2 mm) are almost unidentifiable due to heavy alteration and corrosion with some replacement by calcite. Pyroxenes are all altered to orange-brown forms which have been termed 'ocelli', with the alteration products containing high aluminium content.

The breccia has a matrix dominated by quartz grains and macerated, dark carbonaceous siltstone. Other mineral grains include microcline, muscovite, and minor calcite. The grains are intensely fractured and the average grain size is 1h mm with largest being quartz grains, which are up to 1 mm in size.

149 Figure A.4.i - Reference images for Sample A4-a. The altered dolerite and breccia core is shown in (a). Photomicrographs (a) and (b) show the typical texture and altered plagioclase phenocrysts; the former is cut by a sulphide vein. Ocelli are also shown (d) along with the typical texture of the underlying breccia (e).

150 Sample Reference Number: A4-b Sample name: Cross-laminated sandstone Reference Figure: A.4.ii

Macroscopic Description: Light grey, fine-to-medium-grained micaceous sandstone which is regularly interlaminated with dark grey-black, highly micaceous siltstone lamina generally less than 1 mm thick. Some trough-cross lamination is present with sets up to 5 em - thick. There is also minor wavy lamination present. Calcite cement is present in the matrix.

Microscopic Description:

The sample is composed primarily of quartz, muscovite, carbonaceous materials and calcite cement. The coarsest portions are quartz dominated with the largest grains up to 1 / 2 mm. Microcline grains are also present. The finer laminations show grain sizes of less 1 than / 8 mm and have a higher abundance of muscovite and carbonaceous material.

151 Figure A.4.ii - Reference images for Sample A4-b. The core sequence is shown in (a). Photomicrographs (b) and (c) show the typical texture of the sample.

152 Sample Reference Number: A4-c Sample name: Breccia Reference Figure: A.4.iii

Macroscopic Description: The sample has a creamy-white to white-grey, coarse-grained matrix with small {less than 1 em sized} breccia clasts. A large 10 em planar cross-bedded sandstone clast is present at the top of the sample and a large 12 em clast of planar laminated sandstone clast is present at the base of the sample. Other breccia clasts include:

• dull black, carbonaceous coaly siltstone • lenticular laminated, micaceous siltstone • cream-coloured massive sandstone

Microscopic Description: The sample is composed primarily of grains of milky-white, clear, rose and smoky quartz, all with wavy extinction. Muscovite, microcline and occasional garnet grains are also present along with some macerated carbonaceous siltstone fragments. Calcite cement is present in the breccia matrix.

153 Figure A.4.iii - Reference images for Sample A4-c. The core sequence is shown in (a). Photomicrographs (b) and (c) show the typical texture of the breccia and a planar laminated sandstone clast respectively.

154 Sample Reference Number: AS-a Sample name: Breccia Reference Figure: A.S.i

Macroscopic Description: The sample has a white-grey, medium to coarse-grained sandstone matrix, with breccia fragments with varying sizes which are more concentrated in the lower half of the sample. Breccia clasts and fragments include:

• lenticular-laminated micaceous and carbonaceous siltstone • dull black, carbonaceous coaly siltstone • bioturbated sandstone • flaser-laminated sandstone 1 • semi-rounded, milky-white massive sandstone clasts (less than / 2 em in size) • orange-brown, oxidised and planar cross-bedded, coarse-grained sandstone with grains of quartz, mica and goethite • orange, altered Sample A4-a-type dolerite

Microscopic Description: The matrix contains grains of milky-white, clear, rose and smoky quartz (dominant mineral; shows wavy extinction); muscovite; macerated carbonaceous siltstone 1 1 fragments; occasional microcline and garnet grains. Grain sizes vary from / 8 - h mm on average. The matrix contains calcite.

155 Figure A.S.i - Reference images for Sample AS-a. The core sequence is shown in (a). Photomicrographs (b) and (c) show the typical texture of the breccia. The texture of oxidised and laminated sandstone is shown in (d).

156 Sample Reference Number: AS-b Sample name: Breccia Reference Figure: A.S.ii

Macroscopic Description:

The upper two thirds of this sample consist of cream-coloured massive sandstone. The lower part is a dark grey, carbonaceous breccia with a medium-grained matrix. It contains breccia clasts of:

• dull black, carbonaceous coaly siltstone up to 3.5cm • lenticular laminated, micaceous siltstone • semi-rounded, milky-white massive sandstone (less than 0.7cm in size) • orange, altered Sample A4-a-type dolerite

Microscopic Description: The cream-coloured massive sandstone is composed of grains of milky-white quartz, smoky quartz, microcline and small amounts of muscovite. The grey breccia also contains these mineral grains, in addition to macerated carbonaceous siltstone fragments. It also has a smaller average grain size e; 4 mm) than the sandstone above 1 1 ( h- /z mm).

The dolerite is orange-brown and composed of corroded and altered plagioclase and pyroxene crystals. The pyroxene crystals are very highly altered to orange-brown masses. Phenocrysts of plagioclase are severely corroded and altered and blend in almost entirely with the surrounding matrix. The average crystal size of plagioclase in 1 the matrix is / 2 mm.

157 Figure A.S.ii - Reference images for Sample AS-b. The core sequence is shown in (a). Photomicrographs (b) and (c) show the typical texture of the breccia. The texture of the dolerite fragments is shown in (d) and (e).

158 Sample Reference Number: A6 Sample name: Brecciated siltstone Reference Figure: A.6

Macroscopic Description: The sample is an oxidised, mustard-coloured, fine-grained, laminated glauconitic siltstone which is disrupted by white-grey, coarse-grained, sandstone breccia. The 1 glauconitic siltstone shows steeply-dipping, planar lamination. There is a dark, / 2 mm thick, orange-brown contact zone between the siltstone and the breccia, whilst the contact between the two is lined by calcite. The breccia contains:

• semi-rounded, milky-white massive sandstone clasts • orange-gold, oxidised sulphide minerals • orange, altered Sample A4-a dolerite fragments

Microscopic Description: 1 The siltstone comprises quartz and mica grains less than / 10 mm in size and minor amounts of microcline, cemented by calcite in a fine orange-brown matrix of the same 1 composition. There are abundant lmm long carbonaceous laminations which are / 5 mm wide. The breccia contains angular and poorly sorted grains of quartz (which shows wavy extinction), microcline, muscovite, and clasts as described above. Some fracturing and corrosion of the grains in the breccia is seen particularly in the microcline. The largest grains are quartz (1/z- 1 mm, 3 mm maximum). Calcite is present in the breccia matrix.

159 Figure A.6 - Reference images for Sample A6. The core sequence is shown in (a). Photomicrograph {b) shows the laminated glauconitic siltstone. Depicted in (c) and {d) is the typical texture of the breccia.

160 Sample Reference Number: A7 Sample name: Sandstone breccia Reference Figure: A.7

Macroscopic Description: This is a medium to coarse-grained, grey-white sandstone breccia containing consistently sized (1 - 2 em) breccia clasts. The distribution of the clasts is atypical when compared to most of the other brecciated sequences. The clasts are relatively evenly distributed throughout the sandstone and show some degree of preferred orientation. Clasts include:

• dull black, carbonaceous coaly siltstone • lenticular-laminated, micaceous siltstone. • semi-rounded, milky-white massive sandstone (less than 0.7 em in size)

Microscopic Description: The matrix contains milky-white, clear and smoky quartz, muscovite, biotite, orange­ gold coloured/partially-oxidised sulphide minerals and macerated carbonaceous siltstone fragments. The grains in this breccia are often fractured and are cemented by 1 1 calcite. The largest grains are / 2 - 1 mm and the average grain size is less than / 2 mm.

161 Figure A.7 - Reference images for Sample A7. The core sequence is shown in (a). Photomicrographs {b) and (c) show the typical texture of the breccia.

162 Sample Reference Number: A8 Sample name: Macerated sandstone breccia Reference Figure: A.8

Macroscopic Description: This sample is characterised by a 4 em large, grey-green clast at the top of the core sequence which has an orange, highly oxidised rim. This clast is composed of angular quartz grains with some microcline and a few flecks of muscovite encased in a matrix of sulphides, which give the dark-green clast a slight metallic lustre. These clasts are interpreted as fragments of sulphide concretions which were present before the brecciation event. The remainder of the sample is composed of a cream-coloured massive sandstone clast with a yellow tinge (due to yellow-orange oxidation products and calcite present in the matrix), underlain by sandstone breccia with a few breccia lithoclasts. The breccia fragments include fragments of:

• dull black carbonaceous, laminated siltstone • dark green brecciated sulphide concretion fragments • lenticular laminated, micaceous siltstone • semi-rounded, milky-white massive sandstone (less than 0.7 em) • orange, altered Sample A4-a-type dolerite

Microscopic Description: The sulphide concretion fragments resemble massive sandstone with regards to its basic mineralogy, except to the abundance of sulphide minerals present.

1 The cream-coloured massive sandstone has smaller grains sizes (less than I 4 mm) relative to other massive sandstone samples. It also has an abundance of calcite present in the matrix. The dominant mineral grain types include quartz and microcline.

The sandstone breccia contains quartz, microcline and minor amounts of muscovite. There are only a few fragments of carbonaceous materials and siltstone. The average grain size is 1h mm.

163 Figure A.8 - Reference images for Sample A8. The core sequence is shown in (a). Photomicrograph (b) shows a sulphide-rich concretion fragment and (c) shows the texture of a massive sandstone clast. The breccia is represented in (d) and (e).

164 Sample Reference Number: A9-a Sample name: Breccia Reference Figure: A.9.i

Macroscopic Description: This core sequence is characterised by large, orange, Sample A4-a-type dolerite fragments, up to 8 em in size, which constitute 40 % of the sample. They are set in a light-grey, coarse-grained, poorly sorted sandy matrix. The matrix contains sub-angular, milky-white, clear and smoky quartz grains, muscovite, and macerated carbonaceous siltstone fragments. The breccia fragments and clasts include:

• black carbonaceous siltstone • semi-rounded, milky-white massive sandstone clasts • orange-brown, oxidised, coarse grained, sandstone composed of quartz, mica and calcite • dark green brecciated sulphide concretion pieces • orange, Sample A4 -a-type dolerite

Microscopic Description: The mineralogy of the breccia matrix is as follows: quartz with wavy extinction, 1 microcline, perthite and muscovite. The largest grains are quartz grains up to / 4 mm. 1 Average grain size is less than I 3 mm. All grains in the breccia are moderately fractured.

165 Figure A.9.i - Reference images for Sample A9-a. The core sequence is shown in (a). Photomicrographs (b) and (c) show the breccia and a sulphide concretion fragments respectively, whereas (d) and (e) show the texture of altered dolerite fragments at different magnifications.

166 Sample Reference Number: A9-b Sample name: Breccia Reference Figure: A.9.ii

Macroscopic Description: This core sequence has a dark grey colour with abundant breccia clasts. The majority of these clasts are granule-to pebble-sized (4 mm to 16 mm), though some are cobble­ sized (up to 5 em). Black carbonaceous laminated siltstone and dull black, carbonaceous coaly siltstone fragments occur more frequently relative to other samples.

This core sample displays a much greater degree of porosity relative to other samples, with voids of up to 1 em in diameter. The sample has a dark grey, very poorly sorted coarse-grained matrix. It contains milky-white, clear and smoky quartz, muscovite and occasional garnet grains. There is abundant macerated carbonaceous material relative to other samples, which account for the darker grey colour. The matrix contains small amounts of calcite. The breccia fragments and clasts include:

• dull black carbonaceous, laminated siltstone • lenticular laminated, micaceous siltstone • bioturbated siltstone • Sample A6-type oxidised, mustard-coloured, laminated glauconitic siltstone • semi-rounded, milky-white massive sandstone (less than 1h em average) • orange, altered Sample A4-a-type dolerite

Microscopic Description: The most noteworthy microscopic feature of this sample is the very heavy fracturing of all the mineral grains present in the matrix. They appear to have been 'shattered' by deformation. Quartz (with wavy extinction), microcline, and perthite are present with muscovite scattered between them. Macerated carbonaceous siltstone fragments and macerated coal is common. Some sulphide minerals are also present in the breccia.

All grains are angular and poorly sorted with medium-to-low sphericity. The largest 1 grains are microcline up to 3 mm and quartz grains ( / 2 - 1 mm) with average grain size less than 1h mm.

167 Figure A.9.ii - Reference images for Sample A9-b. The core sequence is shown in (a). The photomicrographs show different sections within the sequence including the breccia matrix (b), a siltstone clast (c) and a micaceous siltstone fragment in the breccia (c).

168 Sample Reference Number: A9-c Sample name: Breccia Reference Figure: A.9.iii

Macroscopic Description: This core sequence contains abundant cobble-sized breccia clasts of dull black, lenticular-laminated carbonaceous/coaly siltstone as well as partially oxidised light cream- brown trough cross-bedded sandstone. The clasts are set in a grey, medium- to coarse-grained breccia matrix. Breccia fragments and clasts include:

• dull black, lenticular-laminated carbonaceous/coaly siltstone • lenticular laminated, micaceous siltstone • light cream-colored and brown trough cross-bedded sandstone • semi-rounded, milky-white massive sandstone (less than 1/3 em average) • orange, altered Sample A4-a-type dolerite

Microscopic Description: The breccia matrix contains milky-white, clear and smoky quartz, muscovite, macerated carbonaceous siltstone fragments and carbonaceous materials. Grain sizes vary 1 markedly in some areas, from less than / 4 mm to 2 mm.

169 Figure A.9.iii - Reference images for Sample A9-c. The core sequence is shown in (a). Photomicrograph (b) illustrates the varying clast sizes within the breccia. Photomicrograph (c) shows the typical breccia with carbonaceous materials present.

170 Sample Reference Number: AlO Sample name: Breccia Reference Figure: A.10

Macroscopic Description: A cream-coloured sandstone breccia which contains some large clasts including one large 16 em long, 1 - 2 em wide slab of lenticular-laminated, black carbonaceous, partly coalified siltstone. This clast is orientated perpendicular to the horizontal. The sandstone breccia contains grains of milky-white, clear and smoky quartz (dominant mineral), muscovite, biotite, occasional garnet as well as oxidised minerals (goethite).

Faint trough cross-bedding is present near the top of the sample due to large trough cross-bedded sandstone clasts which have a matrix similar in colour to the breccia itself. The clasts are noticeable due to the fact that the over steepened cross-bedding. Breccia fragments and clasts include:

• dull black carbonaceous, laminated siltstone • lenticular laminated, micaceous siltstone • dull black coal fragments less than 3 mm in size • cream-brown trough cross-bedded sandstone • semi-rounded, milky-white massive sandstone (less than 1h mm in size) • orange-brown, oxidised, coarse grained, sandstone composed of quartz, mica and calcite • orange, altered Sample A4-a-type dolerite

Microscopic Description: 1 The breccia matrix contains fractured grains with sizes ranging from / 4 - 1 mm on average. Milky-white, clear and smoky quartz, microcline (some of which contain perthite) are present. Lesser amounts of muscovite, macerated carbonaceous siltstone fragments and occasional sulphide minerals can also be seen. There are small amounts of calcite present.

171 Figure A.lO - Reference images for Sample AlO. The core sequence is shown in (a). The photomicrographs show a various sections including breccia (b), trough cross-bedded sandstone and underlying breccia (d).

172 Sample Reference Number: All Sample name: Planar laminated sandstone Reference Figure: A.ll

Macroscopic Description: Light-grey, planar-laminated, medium-grained sandstone with parallel to sub-parallel laminations of dark grey-black micaceous siltstone. This sequence is structurally offset. The laminations dip steeply from the horizontal, which is abnormal.

Microscopic Description: The sample contains quartz, microcline and abundant muscovite with some 1 carbonaceous materials. The average grain size is / 8 mm.

173 Figure A.ll - Reference images for Sample All. The core sequence is shown in (a) with a photomicrograph in (b). Note the atypically steep dip of the laminations indicating that the sample is not in situ.

174 Sample Reference Number: A12 Sample name: Breccia Reference Figure: A.12

Macroscopic Description: The top 12 - 13 em consists of milky-white, coarse-grained massive sandstone, separated from a 2 em-thick zone of coarse breccia by a sharp contact. Another sharp contact leads to an oligomict small pebble paraconglomerate. Sub-rounded, milky microcline clasts up to 1 em in diameter occur throughout the conglomerate.

Microscopic Description: Milky-white massive sandstone: Moderately sorted and composed of grains of milky­ white quartz (dominant), smoky quartz, minor muscovite, biotite, occasional garnet and rose quartz. All grains show moderate fracturing.

Breccia Zone: The mineralogy consists of fractured grains of quartz with wavy extinction, microcline with some perthitization, muscovite and sulphides. The largest 1 grains are quartz and microcline ( / 2 - 1 mm), occasionally up to 4 mm in diameter.

Paraconglomerate zone: Medium-to-coarse-grained, calcite- cemented rock with abundant garnet grains, smoky, clear and rose quartz grains, microcline and some 1 garnets all with grain sizes of less than / 2 mm. Grains are poorly sorted and sub­ rounded. They are highly fractured, with calcite occurring within in some of the larger fractures.

175 Figure A.12 - Reference images for Sample Al2. Image (a) shows the core sequence. Photomicrographs show the texture of the overlying sandstone (b), the breccia (c) and the underlying conglomerate (d).

176 Sample Reference Number: A13-a Sample name: Breccia Reference Figure: A.13.i

Macroscopic Description: The top 10 em consists of immature, medium-grained grey wavy-laminated sandstone with wispy laminations of carbonaceous material. Some of the larger 1 - 2 mm thick laminations are partly coalified, with carbonaceous and micaceous siltstone laminations. Grains of the sandstone are sub-rounded, moderately sorted and have medium sphericity.

The remainder of the sample {14 em) consists of immature medium-grained grey sandstone breccia. The breccia contains a 7 em, cream-coloured massive sandstone clast. This clast is brecciated and contains fragments of dull black carbonaceous siltstone. Other clasts and fragments present in the grey breccia include:

• dull black carbonaceous, laminated siltstone • wavy-laminated sandstone-siltstone • coarse grained milky-white massive sandstone • orange, altered Sample A4-a-type dolerite fragments

Microscopic Description: The grey breccia contains fractured grains of quartz, microcline and muscovite with some carbonaceous material present. The average grain size is 1/3 mm. The cream­ coloured sandstone breccia is similar to that of Sample A10.

177 Figure A.l3.i - Reference images for Sample Al3-a. The core sequence is shown in (a). The photomicrographs show the textures of breccia (b), highly altered dolerite (c) and lower breccia (d).

178 Sample Reference Number: A13-b Sample name: Breccia Reference Figure: A.l3.ii

Macroscopic Description: This sample contains abundant lithoclasts of light grey planar-laminated sandstone, interlaminated with dark grey-black micaceous siltstone. These are set in a matrix of dark grey, medium-grained micaceous sandstone breccia. This breccia matrix is quartz dominated (milky-white and smoky quartz grains). Muscovite, carbonaceous siltstone fragments and a few heavy mineral grains are present. A sub-rounded, cobble sized clast of weathered orange, altered Sample A4-a-type dolerite is present at the top of the sample. Prevalent in this sample are the large slabs of light grey, laminated sandstone and siltstone lithoclasts which are up to 13 em long. These are very angular and the laminations dip almost vertically. There are also clasts and fragments of:

• carbonaceous siltstone • lenticular laminated, micaceous siltstone • coal and coalified carbonaceous siltstone • semi-rounded, milky-white massive sandstone up to 1h em in size • orange, altered Sample A4-a -type dolerite

Microscopic Description: The breccia contains quartz (with wavy extinction), microcline, perthite, and muscovite in addition to a high proportion of carbonaceous material. There are some opaque sulphide minerals present. Microcline grains are up to 2 - 3 mm in size, though the average grain size of most minerals is less than 1 mm.

The dolerite fragments are highly altered with little vestige of the original igneous texture. Phenocrysts of plagioclase are only identifiable by their form.

179 Figure A.13.ii - Reference images for Sample A13-b. Image (a) shows the core sequence. Photomicrographs (b) and (c) show the texture of the altered dolerite whereas (d) and (e) show the textures of the breccia with carbonaceous material in the latter.

180 Sample Reference Number: A14-a, A14-b, A14-c Sample name: Breccia Reference Figure: A.14.i and A.14.ii

Macroscopic Description: Samples A14 -a, A14 -b, A14 -c constitute one large sample which was sectioned for ease of analysis. This core sequence is distinguished by its darker grey colour with abundant clasts ranging in size from sand-sized to pebble- and cobble-sized. They are set in a dark grey, medium- to coarse-grained, poorly sorted breccia matrix. The matrix contains grains of milky-white, clear and smoky quartz, muscovite, macerated carbonaceous siltstone fragments, occasional garnet grains, minor heavy minerals and minor calcite. The breccia fragments and clasts include:

• carbonaceous and micaceous laminated siltstone • dull black, carbonaceous coaly siltstone • oxidised, mustard-coloured, laminated glauconitic siltstone • dull black coal fragments • planar laminated sandstone • trough cross-bedded sandstone • cream-coloured massive sandstone breccia 1 • semi-rounded, milky-white massive sandstone up to / 2 em in size • dark green brecciated sulphide concretion fragments • orange, altered Sample A4-a-type dolerite

Microscopic Description: Grains in the breccia matrix include quartz (with wavy extinction), microcline, and perthite with disseminated muscovite. There is a high abundance of carbonaceous materials in the breccia matrix. Some sulphide minerals are also present. The largest grains are microcline up to 3 mm and quartz eh- 1 mm) with average grain size less 1 than / 2 - 1 mm.

The dolerite fragments are highly altered and almost no igneous texture is preserved. Phenocrysts of plagioclase are only identifiable by their form.

181 Figure A.14.i - Reference images for Sample Al4-a, Al4-b, and A14-c. The images show the core sequences which follow in order from one another.

182 Figure A.14.ii - Reference images for Sample A14-a,A14-b, and Al4-c.The photomicrographs illustrate the typical petrographic nature of the breccia (a), the contact between the breccia and altered dolerite clasts (b), and the typical texture of the altered dolerite clasts (c and d).

183 Sample Reference Number: AlS-a, A15-b Sample name: Breccia Reference Figure: A.lS.i

Macroscopic Description: Samples AlS-a and AlS-b constitute a single sample. These samples are virtually identical to Sample A9-b, except for two note-worthy differences: the clast sizes are smaller and there are more orange altered dolerite fragments present.

Microscopic Description: Similar to Sample A9-b. All grains are fractured.

184 Figure A.lS - Reference images for Sample AlS-a and AlS-b. Image (a} and (b) show the core sequences. Photomicrographs (c) and (d) show the typical petrographic nature of the breccia. Note the amount of carbonaceous materials and the degree of fracture in the mineral grains.

185 Sample Reference Number: A15-c Sample name: Brecciated cross-laminated sandstone Reference Figure: A.15.ii

Macroscopic Description: Light grey, medium-grained, cross-laminated micaceous sandstone. It is interlaminated with dark-grey to black carbonaceous and micaceous siltstone. Two large 3 em blebs of light grey, medium to coarse-grained, poorly sorted sandstone breccia are present in the top 8 em of the sample. The cross-lamination of the sample is interrupted by two cross­ cutting, near vertical 'veins' which connect to the blebs of breccia. The 'veins' contain the same breccia material as the blebs i.e. angular grains of milky-white, clear and smoky quartz, muscovite, and macerated carbonaceous siltstone fragments, scattered small (2 - 4 mm) lithoclasts of angular black carbonaceous siltstone and semi-rounded, milky-white massive sandstone clasts (up to 1 mm).

Microscopic Description: The trough cross-laminated sandstone has grains of quartz microcline and abundant 1 mica and carbonaceous materials. The average grain size varies from / 8 mm to 1 mm.

The breccia has weekly fractured quartz and microcline in addition to muscovite, carbonaceous material and clasts of siltstone, all set in calcite cement. The grain sizes 1 are all less than 1 mm, with an average of / 4 mm.

186 Figure A.lS.ii- Reference images for Sample AlSc. Image (a) shows the core sequence. The cut sequence is shown in (b). Photomicrographs (c) and (d) show the typical petrographic nature of the breccia and the cross-laminated sandstone respectively.

187 Sample Reference Number: AlS-d Sample name: Breccia Reference Figure: A.lS.iii

Macroscopic Description: This core sequence has many pebble- and cobble-sized breccia clasts in a dark-grey, coarse-grained, breccia matrix. The matrix contains grains of milky-white, clear and smoky quartz, muscovite, macerated carbonaceous siltstone fragments, occasional garnet grains and minor of calcite. The breccia fragments and clasts include:

• black carbonaceous and micaceous laminated siltstone • dull black, coaly siltstone • wavy laminated sandstone-siltstone • cream-coloured massive sandstone • planar laminated sandstone • semi-rounded, milky-white massive sandstone up to 1h em • dark green brecciated sulphide concretion fragments • abundant orange, altered Sample A4-a-type dolerite

Microscopic Description: All grains in the breccia are highly fractured, with matrix materials filling some fractures 1 in the larger grains. Grain sizes range from / 4 - 1 mm. Quartz with wavy extinction, microcline and muscovite are present in the calcite cemented matrix. There are clasts of oxidised, massive sandstone with similar compositions, roughly 2 em in diameter, which 1 1 are slightly finer grained ( / 4 mm- / 2 mm).

188 Figure A.lS.iii - Reference images for Sample AlSd. Image (a) shows the core sequence. Photomicrographs (b), (c) and (d) show the typical petrographic nature of the breccia at various locations in the sequence.

189 Appendix B - Full descriptions of the petrology and petrography of brecciated core sequence B

Note:

1. The core samples shown here correspond to all core samples from brecciated core

sequence Bas referred to throughout the study.

2. Each sample is described in detail. In order to avoid unnecessary descriptive

repetition, the following aspects apply to the core sequences described here

(unless otherwise stated):

• Any and all breccia clasts found within the core sequences and fragments are

angular and randomly orientated.

• All grains which constitute the sandstones and sandstone breccias are angular to

sub-angular and have medium-to-low sphericity.

• All the sandstones and sandstone breccias are poorly sorted.

• All photomicrographs were taken using plane polarised light.

• All facies labels used correspond to those as indicated in Table 3.2 (p46).

190 Sample Reference Number: B1 Sample name: Relatively unaltered dolerite Reference Figure: B.1

Macroscopic Description: This is a light grey, mafic, aphanitic dolerite (< 1 mm grain size), composed of pyroxene and plagioclase. Localised veins with calcite crystals are present.

Microscopic Description: The dolerite shows typical igneous texture i.e. crystals are randomly arranged in an irregular interlocking fabric. Plagioclase and pyroxene account for 65 %and 35 %of the volume of the rock respectively. The dolerite consists of 75 % matrix and 25 % phenocrysts. Specific details:

1 Matrix: Plagioclase occurs as / 2 mm large, lath-shaped, white to grey crystals, with Carlsbad and albite twinning. They have irregular, corroded edges.

1 Pyroxene occurs as / 4 mm sized, subhedral, pale green to orange crystals. Clinopyroxene is dominant. Orthopyroxene occurs to a lesser extent as prismatic crystals with little or no twinning, which are often intergrown with clinopyroxene. No pleochroism is visible indicating that they are most likely Mg-rich.

Fine grained interstitial plagioclase and pyroxene glass is visible as well as minor amount of chlorite and oxide minerals.

Phenocrysts: Plagioclase phenocrysts are anhedral, lath-shaped and randomly orientated with sizes ranging from 1 - 3 mm. Some show radial growth and occur as small clusters. Carlsbad and albite twinning and oscillatory zoning are present in many of the crystals. Some of these crystals show strings of orthoclase within the plagioclase host.

Pyroxenes phenocrysts are all less than 1 mm in size, subhedral and occur less frequently relative to the plagioclase phenocrysts. They are pale green or pale red-yellow in colour. Minor twinning is observed. Many show an intergrown texture with the plagioclase phenocrysts.

191 Figure 8.1 - Reference images for Sample 81. The dolerite core sample is shown in (a). Photomicrograph (b) shows the typical igneous texture of the sample. Photomicrographs (c) and (d) show twinned orthopyroxene and plagioclase phenocrysts; the former is often overgrown by the plagioclase.

192 Sample Reference Number: B2 Sample name: Dolerite Reference Figure: B.2

Macroscopic Description: A Sample B1-type dolerite with a second generation dolerite vein 5 em wide intersecting the sample at an angle of 45° to the horizontal. The vein is composed of dark grey-black, aphanitic dolerite. The contact between the dolerites is sharp. Both the host and the darker dolerite are cross-cut by 1 mm wide, fine-grained calcite veins.

Microscopic Description: The host to the vein is similar to Sample B1-type dolerite, but it is finer grained. 1 1 Plagioclase crystals are less than / 4 mm and pyroxenes less than / 5 mm in size and there are 1 mm sized phenocrysts present. The dolerite vein consists of lath-shaped plagioclase crystals and circular, fractured, pyroxenes. The average grain size for both is 1 less than I 8 mm in length and diameter respectively. Phenocrysts of plagioclase up to 1 1 / 2 mm in size are preserved which show Carlsbad and albite twinning and exhibit very faint oscillatory zoning. Some of the plagioclase is partly replaced by calcite.

193 Figure 8.2 - Reference images for Sample 82. The core sample is shown in (a). Photomicrographs (b) and (c) show the typical igneous texture of the much finer second generation dolerite, as opposed to the first generation dolerite shown in (d).

194 Sample Reference Number: B3 Sample name: Dolerite Reference Figure: B.3

Macroscopic Description: This is a light-grey, mafic, aphanitic dolerite, composed of pyroxene and plagioclase accounting for 60 % and 40 % of the volume of the rock respectively. Localised 1 mm wide calcite-filled veins occur in the rock. Phenocrysts of plagioclase and pyroxene are present. The dolerite consists of 90% matrix and 10% phenocrysts.

Microscopic Description: Dolerite shows typical igneous texture. All the properties of the minerals are similar to Sample Bl. Thus only sample-specific grain sizes given: in the matrix, plagioclase occurs 1 1 as / 4 mm sized crystals and pyroxene occurs as / 6 mm sized crystals. Fine grained interstitial plagioclase and pyroxene glass is visible. Plagioclase phenocrysts are up to 1 mm in size and pyroxenes phenocrysts are all less than 1h mm in size.

195 Figure 8.3 - Reference images for Sample 83. The core sample is shown in (a). Photomicrographs (b) and (c) show the typical igneous texture of sample.

196 Sample Reference Number: B4 Sample name: Altered dolerite Reference Figure: B.4

Macroscopic Description: This sample is a grey-green, aphanitic, altered dolerite containing 3 - 4 mm sized altered plagioclase phenocrysts.

Microscopic Description: 1 The sample is very fine grained with plagioclase crystals less than / 4 mm in length and 1 altered pyroxenes crystals less than / 8 mm. The minerals are identifiable by form and some preserve their typical features. The plagioclase phenocrysts are altered and many are almost entirely replaced by calcite and minor epidote.

197 Figure B.4- Reference images for Sample B4. The altered dolerite core sample is shown in image (a). Photomicrographs (b), (c) and (d) show the typical texture of dolerite at various magnifications. Note the replacement of plagioclase with calcite.

198 Sample Reference Number: 85 Sample name: Altered dolerite and carbonaceous sandstone Reference Figure: 8.5

Macroscopic Description: The outer 1 - 2 em zones at the top and bottom of the sequence are composed of carbonaceous, micaceous sandstone. The middle 22 em is a grey-green, aphanitic altered dolerite. The contacts with the siltstone are sharp; the top of the dolerite borders a 4 mm wide zone of black, opaque carbonaceous material. An orange and light green zone of altered dolerite, 1 em in thickness, occurs in the dolerite at either end. The remainder of the sample is dark and light green, altered dolerite which contains 1 mm wide cross-cutting veins of calcite and sulphides (including brass-coloured pyrite).

Microscopic Description: 1 The dolerite is highly altered and extremely fine-grained (crystals are less than h 2 mm). Altered plagioclase and pyroxene are identifiable by form at high magnification. Remnant plagioclase phenocrysts (1 mm in length) are present, but are highly altered, corroded and partially replaced by calcite and minor epidote.

The breccia contains 1h mm sized quartz grains microcline, muscovite, interstitial calcite and carbonaceous material. Dolerite is mixed with the breccia at the contact and contains grains of quartz sourced from the breccia. Plagioclase phenocrysts are also trapped in the zone of black, opaque and carbonaceous and altered material.

199 Figure 8.5 - Reference images for Sample 85. Image (a) shows the core sequence. Photomicrographs (b) and (c) show the altered dolerite which is flanked by carbonaceous sandstone (d and e).

200 Sample Reference Number: B6 Sample name: Altered dolerite Reference Figure: B.6

Macroscopic Description: The sample consists of grey dolerite and a steeply inclined 8 em thick, massive calcite vein with a sharp irregular contact. Below the calcite vein is coarse-grained grey sandstone. The dolerite is light grey, aphanitic mafic rock composed of pyroxene and plagioclase. Plagioclase crystals have been partly replaced by calcite. The sandstone is grey, coarse-grained and contains milky-white, clear and smoky quartz and some minor amounts of muscovite and carbonaceous material.

Microscopic Description: 1 The dolerite is composed of 60% plagioclase and 40% pyroxene, with crystal sizes of / 4 1 mm and / 8 mm respectively. The plagioclase shows more radial growth than in previous samples. Few phenocrysts are observed. Furthermore, any apparent phenocrysts may be described more accurately as accumulations or stellate aggregates of plagioclase crystals arranged radially. The minerals are altered and corroded; many have a grainy texture with very few of the typical features of the mineral being preserved. The contact between the calcite and the dolerite is relatively sharp, with some dolerite fragments present in the calcite.

201 Figure 8.6 - Reference images for Sample 86. Image (a) shows the core sequence and photomicrographs (b) and (c) show the texture of the dolerite and the contact with the calcite vein respectively.

202 Sample Reference Number: B7-a, B7-b, B7-c Sample name: Breccia Reference Figure: B.7.i and B.7.ii

Macroscopic Description: This breccia is characterised by granule- to cobble-sized (2 - 12 em) breccia clasts contained within a grey, medium- to coarse-grained sandy breccia. There are also dark grey, medium- to coarse-grained clasts of breccia present within the lighter grey breccia. These darker breccias are coarser grained, richer in macerated carbonaceous material and contain similar clasts and fragments relative to the lighter grey breccia. The breccia fragments and clasts include:

• dull black, carbonaceous coaly siltstone • lenticular-laminated micaceous and carbonaceous siltstone • medium-grained wavy-laminated sandstone and siltstone • bioturbated sandstone • flaser-laminated sandstone • dark grey immature, fine- to medium-grained massive sandstone 1 • cream-coloured massive sandstone (less than / 2 em) • Sample B4-type dolerite

Microscopic Description: The breccia matrix is composed mainly of grains of milky-white, clear and smoky quartz and microcline. It also contains calcite cement and muscovite which are both present with varying amounts throughout the sample. The size of the grains varies greatly with 1 sizes between / 8 mm to lmm being the most common. Macerated carbonaceous and micaceous siltstone fragments may be a few millimetres to a few centimetres large.

203 Figure B.7.i- Reference images for Samples B7-a and B7-b. The core sequences are shown in (a) and (b) respectively.

204 Figure B.7.ii - Reference images for Sample 67-c. Image (a) shows the core sequence and photomicrographs (b,) (c) and (d) show the texture of the breccia where indicated.

205 Sample Reference Number: B8-a, B8-b Sample name: Breccia Reference Figure: B.8.i

Macroscopic Description: These samples are dark grey, medium- to coarse-grained breccias, with many cobble­ sized (12 em) clasts of dull, black, lenticular-laminate carbonaceous siltstone as well as carbonaceous coaly siltstone and coal. The breccia contains fragments and clasts of:

• dull black, carbonaceous coaly siltstone • lenticular-laminated micaceous and carbonaceous siltstone • medium-grained wavy-laminated siltstone • semi-rounded, cream-coloured massive sandstone (less than 5 mm)

Microscopic Description: The breccia contains milky-white, clear and smoky quartz grains, microcline, muscovite, 1 and some calcite cement. The size of the grains varies between / 8 mm to 1 mm in general. Macerated carbonaceous and micaceous siltstone fragments are common with sizes of a few millimetres to a few centimetres large.

206 Figure 8.8.i - Reference images for Samples 88-a and 88-b, with the core sequences shown as image {a) and {b) respectively. Photomicrograph {c) shows the nature of the breccia and {d) the laminations of the lenticular-laminate carbonaceous siltstone.

207 Sample Reference Number: B8-c Sample name: Breccia Reference Figure: B.8.ii

Macroscopic Description: This sample is composed of two types of breccia, containing similar breccia fragments and clasts, but distinguished from each other by their different shades of grey. The two breccias are similar to those of Sample set B7 and Samples set B8 respectively. Both contain granule sized (up to 1 em) breccia clasts of dull, black, lenticular-laminate carbonaceous siltstone, carbonaceous coaly siltstone, coal and other breccia fragments and clasts is described in Sample set 87 and B8, though they are less than 1 em in size.

Microscopic Description: Both breccias contain grains of milky-white, clear and smoky and quartz, muscovite, macerated carbonaceous materials and siltstone fragments. All vary in size and abundance. See descriptions for sample set 87 and 88-a and 88-b for more details.

208 Figure B.8.ii - Reference images for Sample B8-c. Image (a) shows the core sequences. Photomicrographs (b) and (c) show the nature of the two different breccias.

209 Sample Reference Number: B9-a, B9-b, B9-c, B9-d Sample name: Breccia Reference Figure: B.9.i and B.9.ii

Macroscopic Description: The top 10 em of Sample B9-a follows from Sample B8-c and is similar in appearance. The rest of the sequences also follow from one another and may be discussed as a single sequence.

The breccia contains very coarse sand- to cobble-sized (1- 11 em) breccia clasts within a dark to light grey, medium- to coarse-grained sandy matrix. The matrix contains some calcite cement and is composed of grains of milky-white, clear and smoky quartz in varying proportions to each other throughout the sample. The matrix also contains macerated carbonaceous siltstone fragments, muscovite, and occasional garnet grains. Sample B9-c contains a 20 em section composed of cream-coloured massive sandstone which may be described as a quartz arenite. It has sharp, irregular contacts with the rest of the sample. Sample B9-d contains fragments of Sample B4-type dolerite at its base. The last 1 em is green, discoloured, medium-grained sandstone which was in contact with a large dolerite clast. It is composed of quartz and some macerated carbonaceous siltstone fragments. The breccia fragments and clasts include:

• dull black, carbonaceous siltstone • dull black, coaly, laminated siltstone with visible pyrite in some of the lamina • black carbonaceous, gravelly siltstone • grey medium-grained wavy-laminated siltstone • dull black lenticular-laminated siltstone • light grey, fine- to medium-grained planar cross-bedded sandstone • light grey, fine- to medium-grained planar laminated sandstone • dark grey, medium-grained bioturbated, planar laminated sandstone • semi-rounded, cream-coloured massive sandstone (less than 4 mm in size)

Microscopic Description: The breccia is composed of grains of milky-white, clear and smoky quartz, microcline 1 and muscovite with minor calcite cement. The size of the grains varies between / 8 mm 1 to /2 mm on average. The mineral grains are all moderately to highly fractured. Macerated carbonaceous and micaceous siltstone fragments and materials with varying sizes occur frequently throughout the matrix.

210 Figure B.9.i - Reference images for Samples B9-a and 87-b. The core sequences are shown in (a) and (b) respectively.

211 Figure 8.9.ii - Reference images for Samples 89-c and 89-d. The core sequences are shown in (a) and (b) respectively. Photomicrographs (c) and (d) show the breccia.

212 Sample Reference Number: BlO-a, BlO-b Sample name: Breccia Reference Figure: B.lO.i and B.lO.ii

Macroscopic Description: These breccia samples are dark to light grey, medium- to coarse-grained sandy matrix with very coarse sand-sized to cobble-sized (1 - 10 em) breccia clasts. They are similar to Sample Set B9, although there are more dolerite breccia fragments present in these samples. The breccia matrix is composed primarily of milky-white, clear and smoky quartz in varying proportions to each other. The matrix also contains macerated carbonaceous siltstone fragments, muscovite, and occasional garnet grains and calcite cement. The breccia fragments and clasts include:

• dull black, carbonaceous siltstone • black carbonaceous, gravelly siltstone • dull black lenticular-laminated siltstone with lamina of very coarse sand • grey medium-grained cross laminated sandstone siltstone • grey, fine to medium-grained massive sandstone • light grey, fine- to medium-grained planar laminated sandstone • semi-rounded, cream-coloured massive sandstone (less than 4 mm in size) • Sample B4-type dolerite

Microscopic Description: 1 The breccia has a matrix composed of fractured grains with an average size of / 2 mm, with minor amounts of calcite cement present in between them. The minerals include quartz, which is the dominant mineral, and a lesser amount of muscovite, minor amounts of microcline, and carbonaceous material. There are many 1 - 2 mm sized clasts of micaceous and carbonaceous siltstone present in the matrix. Further down the sequence, the intensity of fracturing of the mineral grains present in the matrix increases. The relative amounts of carbonaceous material and siltstone clasts decreases with depth.

213 Figure B.lO.i- Reference images for Samples BlO-a and BlO-b. The core sequences are shown in (a) and (b) respectively.

214 Figure B.lO.ii - Reference images for Samples BlO-a and BlO-b. Photomicrographs (a) and (b) show breccia from Sample BlO-a with siltstone clasts and opaque carbonaceous material; (c) and (d) in comparison from Sample BlO-b shows less carbonaceous material.

215 Sample Reference Number: 811-a, 811-b, 811-c, 811-d Sample name: Doleritic Breccia Reference Figure: B.11.i and B.11.ii

Macroscopic Description: These continuous breccia sequences are characterised by abundant granule- to cobble­ sized (2 - 10 em) dolerite breccia clasts contained within a grey, medium- to coarse­ grained sandy matrix. The breccia fragments are highly angular and randomly orientated. The matrix contains abundant calcite cement and is composed mainly of grains of milky-white, clear and smoky quartz, mixed with macerated carbonaceous siltstone fragments and muscovite. The colour of the matrix varies between dark and light grey depending on the abundance of milky-white quartz to macerated carbonaceous fragments.

The dolerite fragments in the breccia are all altered. They are aphanitic, light to dark green and have microfractures and fractures filled with calcite and some sulphides. The calcite veinlets are up to 2 mm thick. There are also occasional accumulations of euhedral pyrite crystals up to 1mm in size throughout the dolerite. Replacement of plagioclase by calcite is common.

The section between 811-a and 811-b contains a 14 em large coarse-grained, cross­ bedded sandstone dast composed of milky-white, clear and smoky quartz, macerated carbonaceous siltstone fragments and muscovite. This sandstone contains faint cross­ bed sets up to 2 em thick, inclined at roughly so to the horizontal. They have higher abundances of muscovite and smaller grain sizes, relative to the rest of the sandstone.

There are few other breccia fragments or clast types present besides the dolerite and sandstone clasts, which are also semi-rounded, cream-coloured massive sandstone clasts scattered throughout the breccia which are less than 5 mm in size.

Microscopic Description: The breccia matrix contains mildly fractured grains of quartz, microcline, perthite, muscovite and calcite cement. Minor macerated carbonaceous material is present in addition to sulphides. The largest grains are quartz grains, which are up to 3 mm in size. 1 The average grain size is between less than / 4 - 1 mm. Fragments of dolerite as small as 2- 3 mm in length are present in the breccia.

Dolerite fragments are highly altered. The minerals show few typical features, but plagioclase still retains its basic habit and remnants of zoning are occasionally preserved. The plagioclase is mostly re-crystallised and partly replaced by calcite.

216 Figure B.ll.i - Reference images for Samples Bll-a, Bll-b and Bll-c. The core sequences are shown in {a), {b) and {c) respectively overlie one another.

217 Figure B.ll.ii - Reference images for Samples B11-a, B11-b and B11-c. The photomicrographs show: (a) the breccia; (b) a dolerite fragment in the breccia; (c) zoned altered plagioclase phenocryst in the altered dolerite; (d) the dolerite under high magnification.

218 Sample Reference Number: B12-a, B12-b, B12-c, B12-d Sample name: Breccia Reference Figure: B.12.i and B.12.ii

Macroscopic Description: These continuous sections of the core consist of a light grey fine- to medium-grained breccia which contains fewer, smaller breccia fragments relative to other samples. It is 'better sorted' relative to other breccia samples which have larger ranges of clast sizes. The clasts are relatively evenly distributed throughout the sandstone. The breccia matrix consists of grains of milky-white, clear and smoky quartz, muscovite, macerated carbonaceous siltstone fragments and other carbonaceous materials. The breccia clasts and fragments vary in size from a few mm up to 2 em. They include:

• lenticular laminated, micaceous siltstone • dull black, carbonaceous coaly siltstone • light grey, medium- to fine-grained massive sandstone clasts, interlaminated with dark grey-black, micaceous siltstone; these are most likely clasts of planar-laminated, cross-bedded and trough cross-bedded sandstone • semi-rounded, cream-coloured massive sandstone (less than 8 mm)

Microscopic Description: The breccia is composed of quartz with wavy extinction, microcline, and muscovite. 1 Micaceous siltstone clasts 2 - 3 mm are common. The average grain size is I 4 mm, although larger grains up to 1 mm are present. Grains are commonly fractured. There is fine-grained interstitial material with the same mineralogy as the breccia and minor calcite cement in the matrix.

219 Figure 8.12.i -Reference images for Samples 812-a, 812-b and 812-c. The core sequences overlie one another and are shown in (a}, (b) and (c) respectively.

220 Figure B.12.ii - Reference images for Sample B12-d. The core sequence follows from B12-c. The photomicrographs (b) and (c) show the typical petrographic nature of the breccia for samples B12-a to B12-d.

221 Sample Reference Number: 813-a, 813-b, 813-c, 813-d, 813-e Sample name: Breccia Reference Figure: B.13.i, B.13.ii and B.13.iii

Macroscopic Description: These sequences are composed primarily of grey, medium-grained sandstone breccia. They all have similar matrix compositions. The type of breccia clasts and fragments vary. In Sample 813-a the breccia fragments are smaller (2 em maximum size) relative to other B13 samples. They are mainly lithoclasts of:

• lenticular-laminated, micaceous siltstone • grey medium- to fine-grained sandstone • light grey medium- to fine-grained interlaminated sandstone-siltstone • semi-rounded, cream-coloured massive sandstone (up to 1 em in size)

In Samples 813-b and 813-c, the breccia contains cobble-sized altered dolerite fragments which are frequently altered to a cream-white colour. These cream-white portions appear to have undergone partial melting and leaching and occur on the edges of larger fragments or as thin (less than 1 em wide) smears within the breccia. There are few other breccia fragments or clast types present besides the dolerite. Sample 813- dcontains two cobble-sized clasts. One is cross-laminated sandstone and the other is as cream coloured massive sandstone. Sample 813-e consists primarily of grey, cream­ coloured sandstone breccia which is almost structureless. There is, however, a change near the bottom of the sample, where the breccia has many coarse sand to pebble-sized clasts and fragments. These include carbonaceous siltstone and lenticular laminated, carbonaceous and micaceous siltstone.

Microscopic Description: The breccia has grains of milky-white, clear and smoky quartz and lesser amounts of 1 1 microcline and muscovite. The average grain size is / 4 mm to / 2 mm. There is abundant fine-grained interstitial material with the same mineralogy. There is minor calcite cement in the matrix together with varying amounts of carbonaceous material.

The dolerite fragments in Samples 813-b, 813-c and 813-d are highly altered. Plagioclase crystals retain their original form, but are partially replaced by calcite. There are many 1h mm wide cross-cutting calcite veins present filled replaced with breccia. Many dolerite fragments are partially melted; they display various zones distinguished by their degree of alteration or melting. These include zones which have undergone partial of complete melting.

222 Figure B.13.i - Reference images for Sample B13-a. Photomicrograph (b) shows the breccia and (c) and (d) demonstrate the highly altered dolerite fragments in the breccia.

223 Figure B.13.ii- Reference images for Samples B13-b. The core sample is shown in image (a). The photomicrograph (b) shows the typical breccia for these samples. The altered dolerite fragments are also all similar and typical examples of the texture are shown in photomicrograph images (c) and (d).

224 Figure 8.13.iii - Reference images for Samples 813-c, 813-d and 813-e. The sequences are shown in (a), (b) and (c) and overlie one another.

225 Sample Reference Number: B14-a and 14-b Sample name: Breccia Reference Figure: B.14.i and B.14.ii

Macroscopic Description: These are dark grey, medium- to coarse-grained sandstone breccias. The top and bottom of Sample B14-a and 14-b are interrupted by thick calcite veins. The bottom of the sample is in sharp contact with Sample B15-a and is separated from it by a fracture along the calcite vein, exposing 1 - 2 mm wide, elongated calcite crystals. The breccia fragments in the samples and clasts include:

• light grey, micaceous, laminated and lenticular-laminated siltstone • black carbonaceous siltstone • dull black, coaly siltstone 1 • semi-rounded, milky-white massive sandstone up to / 2 em in size • planar laminated sandstone

Microscopic Description: The matrix comprises grains of milky-white, clear and smoky quartz, mica, macerated carbonaceous siltstone fragments and calcite cement. There are larger (1 mm sizes) carbonaceous material fragments present in this sample as well as more calcite in the 1 1 matrix relative to other samples. Grain sizes are on average / 5 mm to h mm, with a few large grains up to 1 mm.

226 Figure 8.14.i - Reference images for Samples 814-a and 814-b. The sequences are shown in images (a) and (b). They overlie one another.

227 Figure 8.14.ii - Reference images for Samples 814-a and 814-b. The photomicrographs show: (a) the typical petrographic nature of the breccia; (b) and (c) opaque carbonaceous materials, siltstone clasts and perthite grains in the breccia.

228 Sample Reference Number: 815-a and 15-b Sample name: Brecciated dolerite Reference Figure: B.15.i and B.15.ii

Macroscopic Description: These are samples of dark green-black, aphanitic dolerite. They have been pervasively intruded by veins of calcite veins 1 mm to 1.5 em wide which cut at random directions through the samples.

Microscopic Description: The dolerites here are altered, but preserve the typical igneous texture. The average crystal size is small and all are intensely fractured. The crystals have irregular and corroded edges. The pyroxene crystals are the most highly altered. They occur as fine­ grained orange-brown mineral forms, or as ocelli which have been also been partially replaced by calcite. In areas where the intrusion of calcite veins is more frequent, melting has occurred between the veins to produce zones of extreme alteration where epidotisation is also common. These zones are distinguished from the matrix by their orange-brown colour. Plagioclase and pyroxene crystals here are partially or completely replaced by calcite.

229 Figure B.lS.i - Reference images for Samples BlS-a and BlS-b. The core sequences are shown in images (a) and {b) and follow from one another.

230 Sample Reference Number: 815-a and 15-b Sample name: Brecciated dolerite Reference Figure: B.1S.i and B.15.ii

Macroscopic Description: These are samples of dark green-black, aphanitic dolerite. They have been pervasively intruded by veins of calcite veins 1 mm to 1.5 em wide which cut at random directions through the samples.

Microscopic Description: The dolerites here are altered, but preserve the typical igneous texture. The average crystal size is small and all are intensely fractured. The crystals have irregular and corroded edges. The pyroxene crystals are the most highly altered. They occur as fine­ grained orange-brown mineral forms, or as ocelli which have been also been partially replaced by calcite. In areas where the intrusion of calcite veins is more frequent, melting has occurred between the veins to produce zones of extreme alteration where epidotisation is also common. These zones are distinguished from the matrix by their orange-brown colour. Plagioclase and pyroxene crystals here are partially or completely replaced by calcite.

229 Figure 8.15.ii - Reference images for Samples 815-a and 815-b. The photomicrographs show: {a} the typical dolerite texture with altered and fractured minerals; {b) the matrix at higher magnification; {c) and {d) alteration and melt zones between calcite veins.

231 Appendix C - Petrology and petrography of representative samples from the standard core sequence.

Note:

1. The core samples shown here were chosen due to their applicability to the mineral­

chemical, geochemical and isotopic techniques employed in this study. Further

details regarding the lithologies present in the study are may be found in Chapter 3.1. 2. Dolerite samples are listed from Types 1 to 3 (STD-DOL 1 to 3).

3. Sedimentary rock samples are listed from Types 1 to 3 (STD-SED 1 to 3).

4. Samples STD-DOL lto 3 were used for mineral chemical analyses (Chapter 3.3).

5. Samples STD-DOL 1 to 3 and STD-SED 1 to 3 were used for whole rock geochemical

analyses (Chapter 4).

6. Calcite extracted from veins in a STD-DOL1 sample was used as a standard for stable

isotope analyses (Chapter 5).

7. Sedimentary rock samples were chosen on a basis of their grain size and mineralogy.

Massive samples were selected over carbonaceous, bedded, laminated or

bioturt.bated samples to obtain the best mineralogical and whole rock geochemical

representations possible using the available analytical instrumentation.

232 Reference Number: STD-DOL 1 Sample name: Standard dolerite Type 1 Reference Figure: C.1

Macroscopic Description: A light grey aphanitic dolerite composed primarily of pyroxene and plagioclase feldspar with occasional microfractures filled with calcite.

Microscopic Description: The dolerite has all crystals are arranged in an irregular mesh and comprises 80 % matrix and 20 % phenocrysts. Plagioclase and pyroxene account for 55 % and 35 % of the volume of the rock respectively, with the remainder comprising of iddingsitic olivine, chlorite and oxides. Further details follow:

1 Matrix: Plagioclase occurs as / 2 mm long lath-shaped crystals which show both Carlsbad and albite twinning.

Pyroxene occurs primarily as augite and pigeonite. The lack of 1 pleochroism in the subhedral, / 4 mm sized crystals indicate more Mg­ rich compositions. Some enstatite and ferrosilite is present associated with the pyroxenes.

Chlorite, opaque oxides (ilmenite) and fine-grained plagioclase and pyroxene glass occur between the larger crystals. Chlorite occurs in slightly higher amounts relative to other standard samples.

Phenocrysts: Anhedral, 1 - 2 mm long plagioclase phenocrysts occur with the same characteristics of plagioclase crystal present in the groundmass. The phenocrysts also exhibit oscillatory zoning and can have show strings of orthoclase present.

1 Clinopyroxene phenocrysts are smaller (less than / 2 mm) relative to the plagioclase phenocrysts. They are pale green or pale red-yellow in colour and bluish or pinkish when thick. The crystals are subhedral, and some show twinning in the form of a single twin-plane.

Rare olivine phenocrysts are present, less than 1/2 mm in size and are iddingsitic in composition.

233 Figure C.1 - Reference images for Type 1 dolerites (STD-DOL 1). A dolerite core sample is shown in (a). Photomicrographs (b) and (c) show the typical texture of the sample.

234 Reference Number: STD-DOL 2 Sample name: Standard dolerite Type 2 Reference Figure: C.2.i and C.2.ii

Macroscopic Description: The Type 2 dolerite is represented by three dolerite core samples which are geochemically similar to Type 3 dolerites. These dolerites are aphanitic with occasional fractures and microfractures filled with calcite and patches up to 10 em in size which are coarse grained.

Microscopic Description: The dolerites have typical igneous textures and comprise between 80- 90% matrix and 10 - 20 % phenocrysts. Plagioclase and pyroxene account for 55 % and 35 % of the volume of the rocks respectively. The remainder comprises chlorite and oxides and rare iddingsitic olivine.

Matrix: Plagioclase occurs as 1/z -1 mm long lath-shaped crystals with Carlsbad and albite twinning.

Pyroxene occurs primarily as augite and occasional pigeonite

Interstitial chlorite, opaque oxides (ilmenite and Ti-magnetite), rare iddingsitic olivine and fine-grained plagioclase and pyroxene occur throughout the samples.

Phenocrysts: Plagioclase phenocrysts (1 - 2 mm) show the same characteristics of plagioclase crystals present in the matrix, although compositional zoning is sometimes visible.

1 Clinopyroxene phenocrysts (less than / 2 mm) occur as subhedral crystals which occasionally show twinning in the form of a single twin-plane.

lddingsitic olivine phenocrysts are present but rare and less than 1/z mm in size.

235 Figure C.2.i - Reference images for Type 2 dolerites (STD-DOL 2). Representative dolerite core samples are shown in (a), (b) and (c) and which display the aphanitic texture of these samples, except for the with occasional coarser grained patches present (b).

236 Figure C.3.ii - Reference images for Type 2 dolerites (STD-DOL 2).The photomicrographs correspond to and illustrate the typical petrographic nature of the dolerites from Figure C.-2 (a), (b) and (c).

237 Reference Number: STD-DOL 3 Sample name: Standard dolerite Type 3 Reference Figure: C.3.i and C.3.ii

Macroscopic Description: This dolerite Type is represented by two dolerite core samples which are geochemically similar to the Type 2 dolerites. They are structureless except for occasional coarser grained patches (1 em is size), and have fewer phenocrysts and are coarser grained then the Standard dolerite Type 2 dolerites.

Microscopic Description: The dolerites have typical igneous textures. They comprise between 90 % matrix and 10 % phenocrysts. Plagioclase and pyroxene account for 55 %and 35 % of the volume of the rocks respectively, with chlorite and oxides and rare iddingsitic olivine accounting for the remaining 10 %.

1 Matrix: Plagioclase occurs as lath-shaped, I 2 - 1 mm long crystals with Carlsbad and albite twinning.

Pyroxene occurs primarily as augite and less frequently as pigeonite

Chlorite, opaque oxides such as ilmenite and Ti-magnetite and fine­ grained plagioclase and pyroxene in-between larger crystals. Rare iddingsitic olivine is present.

Phenocrysts: Plagioclase and pyroxene phenocrysts occur less frequently than in other dolerite standards and are subhedral up 11hmm in size respectively.

238 Figure C.3.i - Reference images for Type 3 dolerites (STD-DOL 3). Representative dolerite core samples are shown in (a) and (b).

239 Figure C.3.ii - Reference images for Type 3 dolerites (STD-DOL 3). The photomicrographs correspond to and illustrate the typical textures of the dolerites from Figure C.-4 (a) and (b.

240 Reference Number: STD-DOL 3 Sample name: Standard dolerite Type 3 (chilled margin) Reference Figure: C.3.iii

Macroscopic Description: A light grey extremely fine-grained chilled margin of the STD-DOL 3-Type, composed primarily of pyroxene and plagioclase feldspar.

Microscopic Description: The dolerite has typical igneous texture, but is extremely fine grained and contains no phenocrysts. Plagioclase and pyroxene account for 60% and 45% of the volume of the rock respectively, with the remainder comprising of chlorite, oxides and possibly smectite and goethite. Further details follow:

1 1 Matrix: Plagioclase occurs as / 8 - I 2 mm long crystals which show both Carlsbad and albite twinning.

1 Pyroxene occurs as augite and with subhedral, less than / 4 mm sized crystals.

Chlorite, opaque oxides (ilmenite), fine-grained plagioclase and pyroxene, as well as smectite and goethite scattered throughout the sample.

241 Figure C.3.iii -Reference images for Type 3 dolerites chilled margin (STD-DOL 3). A dolerite core sample is shown in (a). The photomicrograph shows the extremely fine-grained nature of the dolerite and its typical texture.

242 Reference Number: STD-SED 1 Sample name: Very coarse-grained sandstone Reference Figure: C.4

Macroscopic Description: A white-grey, very coarse sandstone, with grain sizes and mineralogy representative of the coarser lithologies present throughout the standard core sequence.

Microscopic Description: This rock contains very angular, poorly sorted grains. The dominant grain sizes are coarse to very coarse (0.5 - 1 mm) with frequent granule sized grains (1 - 2 mm) and some pebble sized grains (2 - 3 mm). Quartz is the dominant mineral present. Microcline and lesser amounts of muscovite are present in addition to fine- to medium-grained interstitial material of similar compositions to whole rock. Some calcite cement is common is present in-between grains in addition to scattered occurrences of carbonaceous material.

243 Figure C.4- Reference images for Type 1 sedimentary rocks (STD-SED 1}. A core sample is shown in (a}. The photomicrograph shows the coarse-grained nature of the sandstone and its typical mineralogy.

244 Reference Number: STD-SED 2 Sample name: Medium-grained sandstone Reference Figure: c.s

Macroscopic Description: A light grey medium-grained sandstone, with grain sizes and mineralogy representative of the typical sandstones present throughout the standard core sequence. Faint cross­ bedding is present throughout the sample.

Microscopic Description: The dominant minerals present in the sandstone include quartz and microcline with interstitial muscovite, carbonaceous material and finer matrix material. The grains are 1 1 all very angular and poorly sorted with sizes ranging between / 6 and / 2 mm. There are coarse grains present throughout the sample with maximum sizes of approximately 4 mm. Some calcite cement is present in the matrix in small quantities.

245 Figure C.S - Reference images for Type 2 sedimentary rocks (STD-SED 2). A core sample is shown in (a). The photomicrograph shows the medium-grained nature of the sandstone and its typical mineralogy.

246 Reference Number: STD-SED 3 Sample name: Flaser-laminated fine-grained sandstone Reference Figure: C.6

Macroscopic Description: Cream-white coloured fine-grained sandstone. The grain sizes and mineralogy represent the typical finer-grained lithologies present throughout the standard core sequence; that is, with the exception of the interlaminated carbonaceous and micaceous components which are mostly present in unison with one another.

Microscopic Description: Very angular and poorly grains of sorted quartz and microcline comprise the bulk of the samples with interstitial carbonaceous material, muscovite and calcite cement. The 1 1 grain size varies from between / 12 mm and / 6 mm on average.

247 Figure C.6- Reference images for Type 3 sedimentary rocks (STD-SED 3). A core sample is shown in (a). The photomicrograph shows the very-fine to fine-grained nature of the sandstone and its typical mineralogy.

248 Appendix D - Mineral chemical analyses of the Standard Core and Brecciated Core sequences.

Note:

1. The dolerite samples from the Standard Core use the same naming scheme as

applied to those dolerites in Appendix C:

• STD-DOL 1

• STD-DOL 2

• STD-DOL 3

2. Abbreviations used in the tables include -

• L.A. - less altered crystal

• A- altered crystal

• H.A.- heavily altered crystal

• P - phenocryst

249 Sample STD-DOLl Sample STO-DOL 2 ....j Mineral: Feldspar (0=8) Mineral: Feldspar (O=B) Ill Comment Core Core Core Core Core Rim Rim Rim Rim Rim Comment Core Core Core Core Core Rim Rim Rim Rim Rim C"' Si02 47.92 49.07 49.85 so 17 46.21 55.30 56.72 62.45 58.61 54.60 5i01 54.10 54.62 54.68 55.35 53.48 62.82 63.50 63.24 59.17 58.55 iD Ti02 0.02 0.04 0.06 0.06 0.02 0.10 0.08 0.02 0.06 0.09 Ti02 0.09 0.09 0.05 0.08 0.08 0.03 0.03 0.02 0.05 0.09 !=' Al 20 3 30.29 29.71 28.97 28.40 30.75 25.93 25.13 21.55 23.87 26.21 Al10 3 27.69 26.95 27.13 26.12 26.96 23.10 22.64 22.18 24.14 23.80 .....

Fe01ot 0.70 0.64 0.68 0.61 050 0.62 051 0.37 0.45 0.66 FeOtot 0.64 0.64 0.61 0.64 0.69 0.44 0.39 0.37 0.43 0.52 MnO 0.00 0.01 0.02 0.02 0.02 0.00 0.00 0.00 0.01 0.02 MnO 0.02 0.00 0.00 0.01 0.00 0.00 0.02 0.00 0.01 0.03 s MgO 0.06 0.14 0.08 0.12 0.07 0.06 0.04 0.13 0.01 0.08 MgO 0.12 0.10 0.12 0.11 0.09 0.02 0.02 001 0.02 0.05 c.o 16.14 15.10 14.04 13.56 16.98 10.37 9.07 4.42 7.47 10.49 12.11 11.52 11.31 10.72 11.88 5.93 5.07 4.57 7.30 7.90 :::::1 C•D I'D Na 0 .., 7 2.84 3.15 3.67 4.13 2.33 5.87 6.31 8.30 7.19 5.62 Na20 4.86 5.34 5.18 5.43 4.83 8.06 8.15 8.45 7.37 7.21 Ill K,o 0.15 0.15 0.21 0.26 0.14 0.43 0.60 1.20 0.62 0.47 K,O 0.23 0.30 0.28 0.32 0.25 0.80 0.91 LOS 0.56 0.51 n Cr20 3 0.00 0.00 0.02 0.00 0.02 0.01 0.00 o.oo 0.00 Cr20 0.00 0.01 0.00 3 0.00 0.00 0.00 0.02 0.00 0.00 0.00 0.00 ::r Total 98.19 98.04 97.60 97.49 97.12 98.73 98.52 98.44 98.41 98.30 Total 99.86 99.56 99.36 98.80 98.26 101.20 100.73 99.89 99.05 98.67 I'D 3 Si 2.23 2.29 2.33 2.34 2.18 2 52 2.59 2.82 2.67 2.51 Si 2.45 2.48 2.49 2.53 2.47 2.77 2.81 2.81 2.67 2.65 ;:;· Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Ill AI 1.66 1.63 1.59 1.56 1.71 1.39 1.35 1.15 1.28 1.42 AI 1.48 1.44 145 1.41 1.47 1.20 1.18 1.16 1.28 1.27 Ill Fetot 0.03 0.02 0.03 0.02 0.02 0.02 0.02 0.01 0.02 0.03 Fe,01 0.02 0.02 0.02 0.02 0.03 0.02 0.01 0.01 0.02 0.02 :::::1 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Ill Mg 0.00 0.01 0.01 0.01 0.00 0.00 0.00 0.01 0.00 0.01 Mg 0.01 0.01 0.01 O.Dl 0.01 0.00 0.00 0.00 0.00 0.00 -

Mineral: Pyroxene (0=6) Mineral; Pyroxene (0=6) -< Comment Core Core Core Core Core Rim Rim Rim Rim Rim Comment Core Core Core Core Core Rim Rim Rim Rim Rim 3

Si02 50.54 50.58 50.25 50.41 50.59 49.44 48.37 48.25 48.99 48.61 Si02 49.99 49.99 52.59 49.94 49.73 50.14 50.69 49.87 50.37 50.28 :::::1 I'D Ti02 0.31 0.30 0.29 0.27 0.31 0.53 0.86 0.99 0.88 0.77 Ti02 0.83 0.90 0.36 0.83 0.95 0.76 0.41 0.79 0.78 0.71 .., Al 0 !.53 Ill 2 3 1.57 2.03 1.63 1.60 0.69 0.96 1.24 1.09 1.17 AI201 1.24 1.38 0.87 1.30 1.49 0.99 0.56 1.00 0.94 1.08 ;;;- FeOtot 7.21 7.13 6.04 7.05 6.32 27.18 20.90 18.83 17.79 20.73 FeOtot 21.02 19.46 19.63 19.92 18.08 23.70 27.94 21.33 20.42 20.95 ....., MnO 0.18 0.18 0.20 0.19 0.17 0.56 0.48 MnO 0.46 0.42 0.45 0.38 0.49 0.58 0.45 0.43 0.43 .., 0.42 0.35 0.39 0.40 0 MgO 17.84 18.34 17.60 18.37 17.85 15.02 11.69 12.71 13.53 12.18 MgO 12.76 13.40 21.07 1337 12.43 12.07 14.51 10.01 11.16 12.89 CaD 19.37 18.85 20.24 18.85 19.81 5.45 15.52 16.15 15.64 14.30 CaO 13.52 14.17 4.91 13.84 15.95 12.32 5.37 16.26 15.44 12.94 3 .-+ Na20 0.22 0.19 0.19 0.19 0.21 005 0.19 0.20 0.21 0.24 Na10 0.22 0.24 008 0.22 0.26 0.17 0.04 0.22 0.18 018 ::r K20 0.01 0.00 0.00 0.00 0.00 002 0.00 0.01 0.01 0.04 K20 001 0.00 0.01 0.00 0.03 0.01 0.01 0.02 0.02 0.01 I'D Crz0 V1 3 0.59 0.64 0.97 0.79 0.82 0.04 0.00 0.01 0.01 0.00 Cr201 0.01 0.00 0.01 0.03 0.01 o.m o.o2 o.oo o.o1 0.01 .-+ Total 97.99 97.98 97.96 97.95 97.83 99.14 99.11 98.95 98.72 98.62 Total 100.28 100.16 100.10 100.06 99.55 100.79 100.24 100.06 99.84 99.61 Ill a.:::::1 s; 1.89 1.89 1.88 1.88 1.89 1.93 1.89 1.87 1.89 1.90 51 1.92 1.91 1.96 1.92 1.92 1.93 1.97 1.94 1.95 1.94 Ill.., r; 0.01 O.Dl 0.01 0.01 0.01 0.02 O.D3 0.03 0.03 0.02 n OD2 0.03 ODl 0.02 oro 0.02 0.01 0.02 0.02 0.02 a. AI 0.07 0.07 0.09 0.07 0.07 0.03 0.04 0.06 0.05 0.05 AI 0.06 0.06 0 04 0.06 0.07 0.05 OD3 0.05 O.M 0.05 n Fe,ot 0.23 0.22 0.19 0.22 0.20 0.89 0.68 0.61 0.58 0.68 Fe tot 0.68 0.62 0.61 0.64 0.58 0.76 0.91 0.69 0.66 0.68 0 Mn 0.01 O.Dl 0.01 0.01 0.01 0.02 0.02 0.01 0.01 0.01 Mn 0.01 0.01 0.01 0.01 0.01 0.02 0.02 0.01 0.01 0.01 ;o Mg 0.99 1.02 0.98 1.02 0.99 0.88 0.68 0.73 0.78 0.71 Mg 0.73 0.76 1.17 0.76 0.71 0~9 0.84 0.58 0.65 0.74 Ill c. 0.78 0.75 0.81 0.75 0.79 0.23 0.65 0.67 0.65 0.60 c. 0.56 0.58 0.20 0.57 0.66 0.51 0.22 0.68 0.64 0.54 Ill N• 0.02 0.01 0.01 0.01 0.02 0.00 0.01 0.02 0.02 0.02 Na 0.02 0.02 0.01 0.02 0.02 0.01 0.00 0.02 0.01 0.01 3 K 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 K 000 000 000 000 000 000 000 000 0.00 o.oo "0 i'D Wo 38.51 37.43 40.56 37.44 39.58 11.36 31.91 32.94 32.01 29.78 Wo 27.96 29.11 9.82 28.47 33.19 25.55 11.22 34.20 32.47 27.04 !" En 49.36 50.68 49.08 50.78 49.63 43.57 33.45 36.07 38.53 35.30 En 36.72 38.31 58.63 38.28 36.00 34.83 42.18 29.30 32.66 37.49 N ,, ,, V1 11.34 11.21 9.66 11.10 10.03 44.88 33.93 30.25 28.68 34.01 34.49 31.68 31.26 32.43 29.83 38.99 46.45 35.66 34.19 34.79 0 Sample STD-DOL 3 Sample STD-DOL3- Margm -t Mineral: Feldspar (0,8) Mineral: Feldspar (0=8) 11.1 C"' Comment Core Core Core Core Core Rim Rim Rim Rim Rim Comment Core Core Core Core Core

Si02 55.67 54.16 53.05 55.09 56.21 61.73 60.81 60.31 60.95 57.65 Si02 54.34 54.81 53.76 53.58 54.23 tD Ti02 0.10 0.07 0.06 0.07 0.08 0.05 0.03 0.05 0.03 0.06 Tr02 0.09 0.09 0.08 0.07 0.07 !=' AI203 26.13 27.07 28.24 26.11 26.02 23.00 23.38 23.54 23.35 25.65 AI203 25.80 25.47 26.12 26.46 25.77 .... FeO,ot 0.63 0.63 0.51 1.41 0.65 0.61 0.55 0.47 0.55 0.65 FeO,ot 0.76 0.74 0.78 0.76 0.74 Mna 0.00 0.01 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 Mna 0.00 0.03 0.04 0.00 0.00 n Mga 0.11 0.19 0.18 0.18 0.09 0.03 0.02 0.01 0.02 0.04 Mga 0.13 0.11 0.17 0.20 0.14 0 :::l Caa 10.44 11.65 12.42 10.58 9.99 4.67 5.98 6.62 6.07 8.72 ceo 11.09 10.28 11.24 11.32 10.69 !:!: Na 20 5.56 4.96 4.35 5.31 5.71 7.96 7.73 7.78 7.96 6.72 Na20 5.57 5.84 5.29 5.09 5.60 :::l K,a 0.33 0.26 0.20 0.31 0.35 1.06 0.76 0.58 0.62 0.36 K,a 0.36 0.37 0.28 0.25 0.32 c ro Cr20 3 0.00 0.03 0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.00 Cr20 3 0.02 0.01 0.00 0.00 0.00 a. Total 99.00 99.06 99.11 99.11 99.18 99.12 99.30 99.40 99.63 99.87 Total 98.17 97.81 97.79 97.73 97.65

s; 2.54 2.48 2.43 2.52 2.56 2.77 2.73 2.71 2.73 2.59 s; 2.50 2.53 2.48 2.48 2.51 Tl 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Tl 0.00 0.00 0.00 0.00 0.00 AI 1.40 1.46 1.53 1.41 1.40 1.22 1.24 1.24 1.23 1.36 AI 1.40 1.38 1.42 1.44 1.40 Fe,," 0.02 0.02 0.02 0.05 0.02 0.02 0.02 0.02 0.02 o.ru Fe tot 0.03 0.03 0.03 0.03 0.03 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 om Mn 0.00 0.00 0.00 0.00 0.00 Mg 0.01 0.01 0.01 0.01 0.01 0.00 0.00 0.00 0.00 0.00 Mg 0.01 0.01 0.01 0.01 0.01 Ca 0.51 0.57 0.61 0.52 0.49 0.22 0.29 0.32 0.29 0.42 Ca 0.55 0.51 0.56 0.56 0.53 Na 0.49 0.44 0.39 0.47 0.50 0.69 0.67 0.68 0.69 0.59 Na 0.50 0 52 0.47 0.46 0.50 K 0.02 0.02 0.01 0.02 0.02 0.06 0.04 0.03 0.04 0.02 K 0.02 0.02 0.02 0.01 0.02

a, 1.88 1.48 1.16 1.80 2.01 6.21 4.34 3.23 3.48 2.01 a, 1.98 2.07 1.58 1.43 1.80 Ab 48.15 42.87 38.34 46.74 49.82 70.83 67.02 65.82 67.91 57.07 Ab 46.67 49.64 45.27 44.22 47.79 An 49.97 55.65 60.50 51.46 48.17 22.96 28.65 30.95 28.61 40.92 An 51.35 48.29 53.15 54.35 50.41

Mineral: Pyroxene (0=6) Mineral: Pyroxene (0=6) Comment Core Core Core Core Core Rim Rim Rim Rim Rim Comment Core Core Core Core Core

Si01 51.10 50.90 52.83 51.11 51.88 49.92 50.30 50.30 49.63 49.42 5i0 2 48.74 49.26 49.13 48.81 48.67

Ti02 0.69 0.60 0.32 0.62 0.43 0.86 0.85 0.65 0.68 0.72 Ti0 2 0.94 0.89 0.87 0.98 0.94

AI201 1.63 1.62 0.75 1.33 0.97 1.15 1.07 0.98 0.92 0.93 AlP] 2.70 2.67 2.56 3.06 2.93

FeOtot 10.87 12.56 18.81 15.13 18.93 20.51 20.11 19.79 23.35 23.88 Fe0101 11.48 13.94 12.45 11.69 12.59 MnO 0.24 0.29 0.43 0.37 0.44 0.45 0.41 0.44 0.51 0.52 MnO 0.29 0.32 0.25 0.24 0.34 MgO 15.02 15.57 21.22 15.21 19.23 11.87 11.85 12.25 11.00 10.22 MgO 14.53 15.92 15.21 15.03 15.41 cao 19.12 16.64 5.29 15.54 6.58 14.61 14.79 15.01 13.41 13.78 CaO 19.54 15.11 17.69 17.96 17.05

Na 20 0.19 0.22 0.07 0.20 0.09 0.17 0.22 0.18 0.17 0.17 Na20 0.22 0.20 0.23 0.23 0.22

K10 0.01 0.01 0.00 0.01 0.00 0.01 0.00 0.00 0.00 0.00 K20 0.01 0.01 0.01 0.03 0.01

Cr0~ 2 o.os 0.07 0.03 0.00 0.03 0.00 0.01 0.00 0.03 0.01 Cr20 3 0.13 0.10 0.07 0.16 0.09 Total 99.21 98.66 99.90 99.79 98.72 99.64 99.80 99.73 99.84 99.76 Total 98.90 98.74 98.68 98.60 98.46

Si 1.93 1.93 1.97 1.93 1.97 1.94 1.95 1.94 1.94 1.94 Si 1.85 1.87 1.86 1.85 1.85 Ti 0.02 0.02 0.01 0.02 0.01 0.03 0.02 0.02 0.02 0.02 Tr 0.03 0.03 0.02 0.03 0.03 AI 0.07 0.07 0.03 0.06 0.04 0.05 0.05 0.04 0.04 0.04 AI 0.12 0.12 0.11 0.14 0.13

Fe101 0.34 0.40 0.59 0.48 0.60 0.67 0.65 0.64 0.76 0.78 Fetot 0.36 0.44 0.39 0.37 0.40 Mn 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.02 0.02 Mn 0.01 0.01 0.01 0.01 0.01 Mg 0.84 0.88 1.18 0.86 1.09 0.69 0.68 0.71 0.64 0.60 Mg 0.82 0.90 0.86 0.85 0.87 Ca 0.77 0.68 0.21 0.63 0.27 0.61 0.61 0.62 0.56 0.58 Ca 0.79 0.61 0.72 0.73 0.69 Na 0.01 0.02 0.01 0.01 0.01 0.01 0.02 0.01 0.01 0.01 Na 0.02 0.01 0.02 0.02 0.02 K 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 K 0.00 0.00 0.00 0.00 0.00

Wo 39.02 34.17 10 59 31.64 13.53 30.60 31.03 31.19 28.18 29.14 Wo 39.69 31.05 36.04 37.02 34.88 En 42.65 44.49 59.13 43.10 55.04 34.59 34.59 35.43 32.17 30.07 En 41.06 45.52 43.12 43.11 43.87 N ,, 17.63 20.52 30.02 24.53 3110 34.16 33.55 32.70 39.00 40.14 ,, 18.44 22.69 19.99 19.02 20.43 ,_.V1 Sample Sample Al -4 Mineral: Feldspar (0=8) Dl Comment Core Core Core Core Core Rim Rim Rim Rim Rim P.core P.core P.core P.core P.core P.rim P.rim P.rim P.rim P.rim C" Si01 51.55 53.26 52.00 54.19 53.81 59.05 58.67 59.43 60.32 60.03 51.87 48.97 49.11 48.62 52.55 53.99 55.38 55.49 53.93 55.25 tD Ti02 0.04 0.04 0.06 0.06 0.04 0.05 0.07 0.06 0.06 0.08 0.05 0.03 0.05 0.05 0.05 0.06 0.06 0.10 0.05 0.09 0 A\20 3 29.80 28.72 29.55 28.24 28.63 25.17 25.16 25.13 24.58 24.75 29.21 31.49 31.44 31.82 29.70 28.54 27.66 27.43 28.79 27.88 t.J FeOtot 0.68 0.56 0.61 0.68 0.64 0.83 1.08 0.79 0.82 1.08 0.52 0.44 0.45 0.43 0.48 0.73 0.72 0.99 0.67 0.72 MoO 0.00 0.00 0.00 0.00 0.04 0.01 0.02 0.02 0.00 0.03 0.01 0.01 0.01 0.00 noo o.o1 no2 o.oo o.oo o.o1 $ MgO 0.14 0.18 0.19 0.14 0.16 0.04 0.04 0.03 0.02 0.04 0.22 0.19 0.21 0.17 0.21 0.13 0.11 0.08 0.12 0.11 CaD 13.95 12.75 13.69 12.11 12.35 8.60 8.68 8.49 7.99 7.95 13.92 15.98 15.94 16.24 ::I 13.59 12.27 11.31 11.06 12.42 11.58 ro Na 20 3.46 4.23 3.72 4.47 4.24 6.29 6.41 6.24 6.44 6.32 3.73 2.23 2.48 2.44 3.34 4.44 4.89 5.00 4.40 4.76 ..... K,O 0.21 0.24 0.19 0.26 0.27 0.62 0.58 0.56 0.66 0.71 0.16 0.12 0.09 0.12 0.17 0.28 0.36 0.39 0.28 0.35 ~ n Cr20 3 0.01 0.00 0.00 0.00 0.01 0.00 0.01 0 01 0.00 0.00 0.01 0.00 0.01 0.00 0.01 0.00 0.00 0.02 0.00 0.00 =r Total 99.84 99.98 100.01 100.15 100.19 100.66 100.72 100.76 100.89 100.99 99.70 99.46 99.79 99.89 100.10 100.45 100.51 100.56 100.66 100.75 ro 3 Si 2.36 2.42 2.37 2.46 2.44 2.64 2.62 2.66 2.69 2.68 2.37 2.25 2.25 2.23 2.40 2.44 2.50 2.50 2.43 2.49 r;· Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 noo o.oo noo noo noo o.oo DJ AI 1.61 1.54 1.59 1.51 1.53 1.33 1.33 1.33 1.29 1.30 1.57 1.70 1.70 1.72 1.60 1.52 1.47 1.46 1.53 1.48 DJ Fetot 0.03 0.02 0.02 0.03 0.02 0.03 0.04 0.03 0.03 0.04 0.02 0.02 0.02 0.02 0.02 0.03 0.03 0.04 0.03 0.03 ::I Mo 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 DJ Mg 0.01 0.01 0.01 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

Mineral: Pyroxene (0=6) -< Comment Core Core Core Core Core Rim Rim Rim Rim Rim P.core P.core P.core P.core P.core P.rim P.rim P.rim P.rim P.rim 3 Si02 49.71 51.07 51.49 50.84 51.73 49.62 50.74 49.34 50.52 49.30 51.78 51.87 51.80 53.12 50.82 49.20 49.74 49.15 48.65 49.29 ::I Ti02 0.90 ro 0.57 0.47 0.65 0.47 0.81 0.66 0.68 0.46 0.73 0.58 0.56 0.56 0.32 0.76 0.97 0.67 0.73 0.70 0.73 ..... DJ A\203 1.90 1.69 1.88 1.62 1.83 1.56 1.52 1.04 0.99 1.06 2.60 2.13 2.54 1.16 3.46 1.60 1.60 0.90 0.99 1.12 Vi" FeD,o 17.38 16.05 15.90 13.45 1 13 33 21.50 18 82 23.71 23.71 21.93 9.54 8.78 10.11 11.00 9.21 21.77 21.83 23.11 25.87 24.93 ...... MnO 0.35 0.38 0.33 0.35 0.31 0.50 0.43 0.50 0.53 0.47 0.24 0.24 0.29 0.31 0.25 0.45 0.48 0.52 0.54 0.45 0 MgO 12.52 15.83 17.20 15.93 17.38 13.38 15.54 11.88 16.90 10.23 16.13 15.27 16.28 18.53 16.05 11.57 11.65 8.61 7.40 9.34 CaO 15.91 13.12 13.77 13.07 13.14 11.41 11.07 11.48 5.16 14.44 18.25 20.33 17.58 14.70 18.07 13.88 13.34 16.22 14.89 13.16 3 Na10 0.21 0.16 0.15 0.17 0.19 0.18 0.15 0.14 0.10 0.16 0.23 0.23 0.20 0.18 0.23 0.18 0.18 0.21 0.17 0.15 s K20 0.01 0.01 0.00 0.02 0.01 0.02 0.02 0.03 0.00 0.00 0.01 0.01 0.01 0.01 0.02 0.02 0.02 0.01 0.02 0.03 ..... ro Cr 0 0.01 0.02 0.04 1 3 0.03 0.05 0.01 0.01 0.00 0.00 0.00 0.27 0.14 0.19 0.14 0.39 0.01 0.00 0.00 0.00 0.03 )> Total 98.90 98.90 98.66 98.58 98.56 98.99 98.96 98.80 98.37 98.32 99.63 99.56 99.56 99.47 99.26 99.65 99.51 99.46 99.23 99.23 Ill DJ Si 1.92 1.94 1.94 1.94 1.95 1.93 1.94 1.94 1.96 1.96 1.92 1.93 1.93 1.97 1.89 1.91 1.93 1.94 1.95 1.96 3 Ti 0.03 0.02 0.01 0.02 0.01 0.02 0.02 0.02 0.01 0.~ 0.02 0.02 0.02 0.01 0.02 0.03 0.02 0.02 0.02 0.02 -o AI 0.09 0.08 0.08 0.07 0.08 0.07 0.07 0.05 0.05 0.05 0.11 0.09 0.11 0.05 0.15 0.07 0.07 0.04 0.05 0.05 iii" fetot 0.56 0.51 0.42 0.51 0.42 0.70 0.60 0.78 0.77 0.73 0.30 0.27 0.31 0.34 0.29 0.71 0.71 0.76 0.87 0.83 !" Mn 0.01 0.01 0.01 0.01 0.01 0.02 0.01 0.02 0.02 0~2 0.01 0.01 0.01 0.01 0.01 0.01 0.02 0.02 0.02 0.02 Mg 0.72 0.90 0.97 0.91 0.98 0.77 0.89 0.70 0.98 Q~ 0.89 0.85 0.90 1.02 0.89 0.67 0.68 0.51 0.44 0.55 Ca 0.66 0.53 0.56 0.53 0.53 0.47 0.45 0.48 0.21 0.61 0.73 0.81 0.70 0.58 0.72 0.58 0.56 0.69 0.64 0.56 Na 0.02 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.02 0.02 0.01 0.01 0.02 0.01 0.01 0.02 0.01 0.01 K 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Wo 33.49 27.20 28.32 27.11 27.15 24.04 23.08 24.37 10.81 31.09 37.45 41.47 36.09 29.62 37.50 29.18 28.23 34.54 32.32 28.46 N Eo 36.67 45.66 49.23 45.99 49.96 39.22 45.08 35.10 49.25 30.65 46.06 43.35 46.51 51.95 46.35 33.85 34.31 25.51 22.35 28.11 IJ1 ,, 29.04 26.54 21.90 26.26 22.18 36.06 31.28 39.99 39.57 37.63 15.64 14.34 16.65 17.78 15 29 36.29 36.77 39.14 44.66 42.84 N Sample Sample A3-a -t I» Mineral: Feldspar (0=8) C" Comment Core Core Core Core Core Rim Rim Rim Rim Rim P.core P.core P.core P.core P.core P.rim P.rim P.rim P.rim P.rim ii) Si02 55.69 54.20 53.29 53.88 53.95 53.35 57.04 56.07 54.20 54.31 50.22 49.00 51.16 49.75 48.63 54.89 57.88 56.14 56.12 57.20 Ti02 0.11 0.08 0.03 0.05 0.08 0.06 0.07 0.06 0.07 0.08 0.06 0.03 0.04 0.03 0.04 0.05 2.33 0.10 0.09 0.08 c

Al20 3 25.83 28.03 29.07 28.70 28.77 25.66 25.68 26.44 27.59 27.40 30.89 31.66 30.20 31.18 31.94 27.19 23.36 26.63 26.57 25.98 ;.., I Fe0101 2.02 0.91 0.72 0.81 0.82 3.18 0.85 0.92 1.00 1.20 0.46 0.42 0.57 0.43 0.41 0.85 1.39 0.85 0.88 0. 72 MnO 0.02 0.01 0.00 0.00 0.00 0.00 n 0.01 0.00 0.00 0.00 0.00 0.00 0.02 0.02 0.00 0.01 0.01 0.02 0.02 0.00 0 MgO 1.23 0.20 0.24 0.26 0.22 1.88 0.06 0.09 0.36 0.35 0.19 0.18 0.22 0.19 0.18 0.15 0.49 0.09 0.12 0.08 :::l CaO 10.21 11.88 12.92 12.78 12.55 11.05 9.85 10.51 11.84 11.83 15.00 16.01 14.29 15.48 16.29 11.60 7.74 10.61 10.69 9.93 !:!". :::l Na10 4.57 4.71 4.11 4.19 4.24 4.27 5.79 5.43 4.62 4.52 2.99 2.53 3.29 2.79 2.38 4.91 6.23 5.37 5.34 5.87 c K20 0.35 0.34 0.20 0.20 0.25 0.27 0.54 0.44 0.28 0.31 0.11 0.08 0.15 0.09 0.08 0.31 0.74 0.39 0.43 0.50 I'D

Cr20 3 0.01 0.02 0.02 0.00 0.02 0.00 0.00 0.00 0.00 0.01 0.00 0.03 0.02 0.00 0.02 0.02 0.01 0.00 0.01 0.01 a. Total 100.04 100.38 100.60 100.87 100.90 99.72 99.89 99.96 99.96 100.01 99.92 99.94 99.96 99.96 99.97 99.98 100.18 100.20 100.27 100.37

Si 2.53 2.45 2.41 2.43 2.43 2.43 2.58 2.54 2.46 2.47 2.30 2.24 2.34 2.28 2.23 2.49 2.62 2.53 2.53 2.57 Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.08 0.00 0.00 0.00 AI 1.38 1.49 1.55 1.53 1.53 1.38 1.37 1.41 1.48 1.47 1.66 1.71 1.63 1.68 1.73 1.45 1.25 1.42 1.41 1.38 Fe,ot 0.08 0.03 0.03 0.03 0.03 0.12 0.03 0.03 0.04 0.05 O.Q2 O.o2 0.02 0.02 0.02 0.03 0.05 0.03 0.03 0.03 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mg 008 0.01 0.02 0.02 0.01 0.13 0.00 0.01 0.02 0.02 0.01 0.01 0.01 0.01 0.01 0.01 0.03 0.01 0.01 0.01 c. 0.50 0.58 0.63 0.62 0.61 0.54 0.48 0.51 0.58 0.58 0.73 0.79 0.70 0.76 0.80 0.56 0.38 0.51 0.52 0.48 0.40 0.41 0.36 0.37 0.37 0.38 0.51 0.48 0.41 0.40 0.27 0.22 0.29 0.25 0.21 0.43 0.55 0.47 0.47 0.51 "'K 0.02 0.02 0.01 0.01 0.01 0.02 0.03 0.03 0.02 0.02 0.01 0.00 0.01 0.01 0.00 0.02 0.04 0.02 0.02 0.03

Dr 2.21 1.95 1.16 1.16 1.45 1.68 3.07 2.51 1.62 1.81 0.64 0.46 0.87 0.52 0.46 1.77 4.43 2.23 2.45 2.82 Ab 43.76 40.96 36.11 36.81 37.39 40.46 49.96 47.11 40.72 40.14 26.34 22.14 29.15 24.47 20.81 42.61 56.67 46.74 46.31 50.23 An 54.03 57.09 62.73 62.04 61.16 57.86 46.97 50.38 57.66 58.05 73.02 77.40 69.97 75.01 78.73 55.62 38.90 51.03 51.23 46.96

Mineral: Pyroxene (0=6) Comment A.core A.core A.core A.core A.core A.rim A.rim A.rim A.rim A.rim P.core P.core P.core P.core P.core P.rim P.rim P.nm P.rim P.rim 5i02 49.29 42.12 41.59 40.70 38.94 49.65 49.65 45.75 47.09 46.15 52.21 51.80 52.54 52.47 51.33 49.89 48.31 42.76 40.00 35.33

Ti01 0.04 0.08 0.14 0.12 0.14 0.04 0.05 0.04 0.04 0.08 0.44 0.47 0.37 0.36 0.75 0.08 0.06 0.07 0.05 0.09

Al 20 3 4.19 8.54 8.33 8.29 8.24 4.57 3.20 4.03 2.97 3.30 2.69 2.84 2.05 2.07 292 3.26 3.31 2.23 3.03 2.15 FeOtot 25.03 23.11 21.67 21.66 22.82 23.63 23.64 24.51 24.08 25.50 8.27 7.61 8.33 8.12 10.50 27.87 27.54 26.86 26.12 26.93 MnO 0.41 0.19 0.12 0.14 0.17 0.39 0.33 0.43 0.33 0.38 0.20 0.21 0.21 0.22 0.24 0.51 0.61 0.56 0.50 0.56 MgO 8.84 12.35 11.75 11.55 11.26 10.58 10.91 9.31 10.07 8.48 16.65 16.16 16.90 17.15 16.68 7.97 6.83 6.32 8.64 5.62 c.o 1.60 1.84 1.80 1.87 1.99 1.31 1.33 1.47 1.05 1.23 18.73 19.97 18.71 18.64 16.97 0.90 0.99 1.10 0.96 1.00

Na20 1.08 0.71 0.97 0.87 1.04 1.04 0.68 1.15 0.72 0.29 0.22 0.27 0.24 0.22 0.25 0.30 0.26 0.29 0.42 0.34 K,o 0.35 0.28 0.26 0.27 0.23 0.38 0.36 0.36 0.15 0.13 0.02 0.00 0.01 0.01 0.00 0.11 0.08 0.11 0.24 0.13

Cr20 3 0.09 0.02 0.02 0.05 0.00 0.04 0.06 0.07 0.09 0.04 0.63 0.72 0.60 0.57 0.18 0.05 0.03 0.06 0.04 0.09 Total 90.92 89.24 86.65 85.52 84.83 91.63 90.21 87.12 86.59 85.58 100.06 100.05 99.96 99.83 99.82 90.94 88.02 80.36 80.00 72.24

Si 2.12 1.79 1.82 1.81 1.75 2.09 2.14 2.04 2.12 2.14 1.92 1.91 1.94 1.93 1.90 2.19 2.20 2.15 1.98 1.98 r; 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.01 O.Ql 0.02 0.00 0.00 0.00 0.00 0.00 AI 0.21 0.43 0.43 0.43 0.44 0.23 0.16 0.21 0.16 0.18 0.12 0.12 0.09 0.09 0.13 0.17 0.18 0.13 0.18 0.14 Fe tot 0.90 0.82 0.79 0.80 0.86 0.83 0.85 0.92 0.91 0.99 0.25 0.23 0.26 0.25 0.33 1.02 1.05 1.13 1.08 1.26 Mn 0.01 0.01 0.00 0.01 0.01 0.01 0.01 0.02 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.02 0.02 0.02 0.02 0.03 Mg 0.57 0.78 0.77 0.76 0.75 0.67 0.70 0.62 0.68 0.58 0.91 0.89 0.93 0.94 0.92 0.52 0.46 0.47 0.64 0.47 c. om 0.08 0.08 0.09 0.10 0.06 0.06 0.07 0.05 0.06 0.74 0.79 0.74 0.74 0.67 0.04 0.05 0.06 0.05 0.06 0.09 0.06 0.08 0.07 0.09 0.09 0.06 0.10 0.06 0.03 0.02 0.02 0.02 0.02 0.02 0.03 0.02 0.03 0.04 0.04 "'K O.Q2 0.02 0.01 0.02 0.01 0.02 O.Q2 O.Q2 0.01 0.01 0.00 0.00 0.00 0.00 000 0.01 0.00 0.01 0.02 0.01

Wo 4.41 4.79 4.88 5.12 5.34 3.53 3.59 4.05 2.92 3.57 38.30 40.73 37.94 37.73 34.64 2.53 2.92 3.38 2.77 3.22 N 34.69 25.21 U"' En 33.91 44.73 44.32 44.05 42.08 39.63 41.02 35.72 38.99 34.24 47.38 45.86 47.68 48.31 47.38 31.12 27.99 27.05 w Fs 56.30 47.14 46.04 46.51 47.53 51.77 52.06 54.49 54.47 60.66 13.51 12.42 13.50 13.16 17.06 64.83 67.70 67.96 60.35 69.59 ';}

Sample Sample A3-b Sample Sample A4-a 0"' Mineraf:Feldspar(0::8) Mineral: Feldspar (0=8) iD Comment Core Core Core Core Core R1m Rim Rim Rim Rim Comment A.P rim A.P.rim A.P.rim A.P.rim A.P.rim A.P.core A.P.core A.P.core A.P.core A.P.core A.core A core A. core A.core A. core 0 SiOz S1.13 52.47 S0.81 S1.66 53.20 54.06 S8.39 S8.44 S7.19 61.13 Si01 49.18 50.19 49.69 47.55 5102 0.07 17.89 20.07 2.77 0.27 55.69 54.20 53.82 52.34 54.88 noz o.o3 o.o5 o.o4 o.o4 o.o9 o.o7 o u 0.10 0.10 0.10 TIOJ 0.01 0.00 O.Ql 0.00 0.00 0.00 0.01 0.00 000 O.Ql 0.10 0.08 0.09 0.09 0.07 N Al 0 29.41 28.42 29.78 29.02 28.22 26.98 24.54 2S.35 26.12 21.37 Al 03 35.75 34.86 34 33 36 60 34.53 0.03 8.06 7.94 215 0.10 25.70 25.27 2497 25.65 24.37 2 3 1 (") FeOtot 0.44 o.ss 0.36 O.S6 0.6S 0.76 0 96 0 66 0.72 3.19 FeOtot 0.39 0.43 0.43 0.20 0.41 1.70 1.17 1.04 2.02 1.70 0.71 0.64 0.68 0.48 0.96 0 MoO 0.03 0.00 0.01 O.Dl 0.00 0.03 0.02 0.00 O.Dl 0.01 MoO 0.00 0.00 0.02 0.00 0.01 0.55 0.44 040 066 0.55 0.01 0.04 0.01 0.00 0.01 :::1 MgO 0.2S 0.21 0.25 0.26 0.18 0.25 0.69 0.06 0.09 2.21 MgO 0 60 0.78 0.82 0.21 0.77 0.64 0.58 0.49 0.82 0.73 0.06 O.G7 0.10 0.12 0.05 !::!. c. a 14.52 13.62 14.86 14.28 12.82 11.92 8.33 9.23 10.26 5.37 C•O 0.19 0 23 0.26 0.12 0.26 62.29 39.36 37.88 55.79 60.10 10.44 10.28 10.05 10.99 9.45 :::1 Na 0 3.43 3.97 3.34 3.70 4 46 4.73 6.60 6.16 5.67 6.10 Na 0 0.15 0.30 0.12 0.06 0.52 0.01 2.31 2.53 008 004 5.65 5.69 5.67 5.16 6.08 c: 2 2 (1) <,a 0.15 0.20 0.14 0.16 0.24 0.30 0.57 0.54 0.44 1.19 K,O 0.23 0.68 0.84 0.15 0.56 0.03 0.07 0.05 0.02 0.01 0.49 0.41 0.50 0.34 0.48 !=1- Cr10, 0.00 0.01 0.01 0.00 0.01 0.02 0.02 0.00 0.00 0.00 Cr103 0.00 O.Dl 0.01 0.01 0.00 0.04 0.00 0.00 0.02 0.00 0.01 0.00 0.03 0.00 0.01 Total 99.39 99.50 99.60 99.69 99.87 99.12 100.23 100.54 100.60 100.67 Total 86 50 87.48 86.53 84.90 88.08 65.36 69.89 70.40 64.33 63.51 98.86 96.68 95.93 95.17 96.36

Si 2.35 2.40 2.33 2.36 2.42 2.47 2.61 2.62 2.57 2.74 2.63 2.66 2.66 260 2.68 O.Dl 1.17 1.30 0.20 0.02 2.54 253 2.53 2.48 2.56 Ti 0 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Ti 0.00 000 0.00 000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 000 0.00 0.00 0.00 AI 1.59 1.53 1.61 1.56 1.51 1.45 1.29 1.34 1 38 113 AI 2.26 217 217 2.35 2.14 0.00 062 0.61 0.18 001 1.38 1.39 138 1.43 1.34 Fetor 0.02 0 02 0.01 0.02 0 02 0 03 0.04 0.02 0.03 0.12 Fetm 002 0.02 0.02 0.01 002 0.10 0.06 0.06 0.12 0.10 0.03 002 0.03 0.02 0.04 Mo 0.00 0.00 0 00 0.00 0.00 0 00 0.00 0.00 0.00 0.00 Mo 0.00 0.00 000 0.00 0.00 0.03 0.02 0.02 0.04 003 0.00 0.00 0.00 0.00 0.00 Mg 0.02 0.01 0.02 0.02 0.01 0.02 0.05 0.00 0.01 0.15 Mg 0.05 006 0.07 0.02 0.06 0.07 0.06 0.05 0.09 0.08 0.00 0.00 0.01 0.01 0.00 C• 0.71 0.67 0.73 0.70 0.62 0.58 0.40 0.44 0.49 0.26 c. O.Ql O.Dl 0.01 0.01 0.01 4.78 2.75 2.64 4.35 4.74 0.51 0.51 0.51 0.56 0.47 N• 0.31 0.35 0 30 0.33 0.39 0.42 0.57 0.54 049 0.53 N• 002 0.03 001 0.01 005 0.00 0.29 032 0.01 0.01 0.50 0.51 0.52 0.47 0.55 K 0.01 0.01 0.01 0.01 0 01 0.02 0.03 0.03 0.03 0.07 K 0.02 0.05 0.06 001 004 0.00 001 0.00 000 0.00 0.03 0.02 0.03 0.02 0.03

0' 0.85 1.13 0.79 0.90 1.35 1.71 3.24 3.06 2.49 7.95 a, 37 24 51.16 67 70 43.86 35.70 0.06 0.19 0.14 0.04 0.02 2.75 2.32 2.85 1.95 2.72 Ab 29.69 34.14 28.68 31.63 38.11 41.08 57.00 53.03 48.76 61.93 Ab 36.92 34.30 14.70 26.67 50.38 0.03 9.58 10.77 0.25 0.12 48.12 48.88 49.06 45.04 52.33 Ao 69.45 64.73 70 52 67.47 60.54 57.21 39.76 43.91 48.75 3013 Ao 25.84 14.53 17.60 29.47 13.92 99.91 90.23 89.09 99.70 99.86 49.13 48.80 48.10 53.01 44.95

Mineral: PyroKene (0=6) Mmeral: PyroKene (0=6) Comment l.A L.A. LA. l.A L.A. A A A A. A. Comment A A A A. H.A H.A. H.A H.A HA

St02 51.65 51.63 51 25 51.20 51.84 46.54 45.88 45.92 45.57 45 05 Si01 51.98 48.01 48.46 47 94 42.00 0.04 0.03 0.43 0.51 0.07

Ti02 0.59 0.59 0.61 0.59 0.57 0.05 0.13 0.03 0.03 0.02 Ti01 0.01 008 0.01 0.01 0.01 0.02 0.02 0.20 0.12 0.02

AI,Ol 2.75 2.45 2.94 2.99 2 23 5.83 5 39 5.88 5.50 5.82 Al,03 31.67 34.28 33.76 31.73 14.82 0.00 O.Ql 0.12 0.19 001

FeOtot 8.22 9.10 7.02 6.93 7.88 19.35 20.89 19.50 19.96 18.82 Fe0 101 0.40 0.37 034 0.52 1.97 38.28 38.06 41.12 37.93 37.32 MoO 0 21 0.25 0.20 0.18 0.20 0.04 0 09 0.06 0.04 0.05 MoO 0.01 0.00 0.00 0.00 000 0.46 0.47 0.91 0.90 0 39 MgO 17.80 16.69 16.49 16.41 16.60 14.06 12.89 13.74 13.42 13.97 MgO 039 0.46 0.61 0.53 2.63 11.55 10.93 10.59 12.10 12.21 c.a 17.51 18.45 19.80 19.83 19.72 0.99 1.63 1.21 0.93 1.11 c. a 0.44 0.32 0.25 0.55 0.10 8.07 8.78 4.71 6.14 7.86

Na_,O 0.21 0.19 0.23 0.23 0.19 1.00 0.74 0.69 0.48 0.97 Na70 2.99 0.49 0.48 0.81 0.09 0.02 0.03 0.05 0.07 0.03 K,O 0.01 0.00 0.00 O.Dl 0.00 0.11 0.19 0.11 0.12 0.13 K,O 0.20 0.21 0.24 0.32 066 0.02 0.02 0.04 0.02 002

Crp 3 0.91 0.39 1.09 1.24 0.35 0.08 0.06 0.11 0.09 0.16 Cr20 3 0.01 0.03 0.02 0.00 0.20 0.00 0.00 0.03 0.00 0.02 Total 99.86 99.74 99.63 99.61 99.58 88.05 87.89 87.25 86.14 86.10 Total 88.10 84.25 84.17 82.41 52.48 58.46 58.35 58.20 58.08 57.95

Si 1.90 1.91 1.89 1.89 1.92 1.98 1.98 1.98 2.00 1.96 Si 2.15 2.11 2.13 2.15 2.53 0.00 0.00 O.Q3 0.04 0.00 Ti 0.02 0.02 0.02 0.02 0.02 0.00 0.00 0.00 0.00 0.00 Ti 0.00 0.00 0.00 0.00 0.00 0.00 o.oo 0.01 0.01 0.00 AI 0.12 0.11 0.13 0.13 0.10 0.29 0.27 0.30 0.29 0.30 AI 1.54 1.77 1.75 1.68 1.05 0.00 0.00 O.Ql O.Q2 000 0.10 2.19 2.42 2.18 2.14 "~ 0.25 0.28 0.22 0.21 0.24 0.69 0.75 0.70 0.73 0.69 Fe tot 0.01 0.01 0.01 0.02 2.19 Mo O.Dl 0.01 0.01 0.01 0.01 0.00 0 00 0.00 0.00 0.00 Mo 0.00 0.00 0.00 0.00 0.00 003 om 0.05 0.05 0.02 Mg 0.98 0.92 0.91 0.90 0.92 0.89 0.83 0.89 0.88 0.91 Mg 0.02 0.03 0.04 0.04 0.24 1.18 1.12 1.11 1.24 1.25 C• 0.69 0.73 0.78 0.78 0.78 0.05 0.08 0.06 0.04 0.05 c, 0.02 0.02 0.01 0.03 O.Dl 0.59 0.65 0.35 0.45 0.58 N• 0.01 0.01 0.02 0.02 0.01 0.08 0.06 0.06 0.04 0.08 N• 0.24 0.04 0.04 0.07 O.Dl 0.00 0.00 O.Dl O.Ql 0.00 K 0.00 0.00 0.00 0.00 0.00 0.01 0.01 O.Ql 0.01 001 K 0.01 0.01 0.01 0.02 0.05 0.00 0.00 0.00 0.00 0.00

wo 35.57 37.43 40.59 40.79 39.88 2.62 4.34 3 26 2.55 2.98 Wo 6.51 14.66 10.98 17.06 1.75 18.15 19.85 11.25 14.02 17.60 Eo 50.32 47.12 47.04 46 97 46.71 51.86 47.80 51.52 5129 52.25 Eo 8.03 29.33 37.29 22.88 63.92 36.14 34.39 35.19 38.44 3805 ,, 13.33 14.76 11.52 11.39 12.71 40.71 44.29 41.86 43.77 40.04 " 5.35 15.38 13.56 14.58 31.49 45.63 45.63 53.34 47.25 44.22 N VI ~ Sample Sample AS·b -t Ill Mineral: Feldspar (0=8) 0" Comment A A. A. A. A. A. A. A. A. A. A. A. ~ A. A. A. A. A. A A. ji) Si01 45.05 46.10 45.43 47.04 51.69 48.09 51.99 49.54 55.22 58.94 59.98 58.42 UM 64.19 62.84 65.14 62.18 66.94 66.94 68.27 Ti02 0.02 0.00 0.00 0.00 0.01 0.00 0.01 0.04 0.01 0.00 0.01 0.01 0.00 0.02 0.03 0.04 0.04 0.00 0.00 0.06 c Al 20 3 30.59 31.52 36.02 36.38 30.07 37.75 30.81 35.06 28.25 23.95 22.66 27.82 n~ 19.43 24.10 20.22 26.41 20.88 20.88 19.55 N

Fe0101 0.46 0.40 0.27 0.28 0.21 0.32 0.16 0.38 0.15 0.40 0.13 0.17 0.10 0.08 0.29 0.11 0.27 0.31 0.31 0.91 MoO 0.00 0.02 0.01 0.00 0.01 0.00 0.00 0.01 0.00 0.04 0.00 0.01 om 0.00 0.00 0 00 0.01 0.00 0.00 0.03 n MgO 0.88 0.80 0.23 0.24 0.23 0.21 0.16 0.23 0.17 0.17 0.11 0.13 om 0.05 0.09 0.04 0.09 0.04 0.04 0.20 0 :::J CaO 0.14 0.14 0.09 0.15 0.16 0.09 0.06 0.15 0.08 0.19 0.33 0.10 0.11 0.13 0.16 0.13 0.13 0.18 0.18 0.28 !:!'. Na20 0.18 0.16 0.16 0.17 3.27 0.11 3.44 1.46 4.96 7.20 8.29 5.82 9.27 10.79 7.73 10.45 7.37 10.33 10.33 11.08 :::J K,O 0.76 0.55 0.09 0.26 0.10 0.12 c 0.09 0.11 0.13 0.14 0.17 0.16 0.10 0.10 0.13 0.17 0.12 0.14 0.14 0.14 ro Cr20 1 0.07 0.06 0.03 0.00 0.00 0.00 0.02 0.02 0.00 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.01 0.01 0.00 a. Total 78.15 79.75 82.33 84.35 85.91 86.68 86.75 87.02 88.98 91.08 91.67 92.60 ~s 94.79 95.37 96.30 96.64 98.83 98.83 100.52

s; 2.67 2.68 2.55 2.58 2.73 2.57 2.72 2.61 2BO 2.88 2.89 2.83 2.~ 2.96 2.94 2.97 2.87 2.98 2.98 2.98 Tl 0.00 0.00 0.00 0.00 0.00 om 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 000 0.00 0.00 0.00 0.00 AI 2.14 2.16 2.38 2.35 1.87 2.38 1.90 2.18 1.69 1.38 1.29 1.59 1.24 1.06 1.33 1.09 1.44 1.10 1.10 1.01 Fewt 0.02 0.02 0.01 0.01 0.01 0.01 0.01 0.02 0.01 0.02 0.01 0.01 0.00 0.00 0.01 0.00 0.01 0.01 0.01 0.03 Mo 0.00 0.00 0.00 0.00 0.00 om 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mg 0.08 0.07 0.02 0.02 0.02 om 0.01 0.02 0.01 0.01 0.01 0.01 0.00 0.00 0.01 000 0.01 0.00 0.00 0.01 c. 0.01 0.01 0.01 0.01 0.01 0.01 0.00 0.01 0.00 0.01 0.02 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 N• 0.02 0.02 0.02 0.02 0.34 0.01 0.35 0.15 0.49 0.~ 0.78 0.55 O.U 0.96 0.70 0.92 0.66 0.89 0.89 0.94 K 0.06 0.04 0.01 0.01 0.02 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

Oc 66.02 60.39 22.02 18.97 4.85 31.18 1.86 5.25 1.81 1.51 1.23 1.33 0.70 0.60 1.08 1.05 1.05 0.88 0.88 0.81 Ab 23.76 26.70 59.49 54.47 92.65 47.39 97.20 89.66 97.33 97.08 96.65 97.75 98.65 98.74 97.80 98.27 97.99 98.18 98.18 97.82 Ao 10.21 12.91 18.49 26.56 2.51 21.43 0.94 5.09 0.87 142 2.13 0.93 0.65 0.66 1.12 0.68 0.96 0.95 0.95 1.37

Mineral: Pyro)(ene (0:6) Comment H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A.

Si02 36.22 10.7Z 14.28 7.65 16.19 9.33 9.10 4.40 5.65 4.51 4.58 5.72 5.55 1.70 3.27 3.51 0.02 0.80 0.05 3.88

Ti02 15.27 0.07 0.39 0.19 0.48 0.76 1.23 0.12 0.19 0.46 0.03 2.90 0.26 0.23 0.07 008 0.05 0.05 0.06 0.42

Al20 3 10.45 9.19 4.36 2.43 4.60 3.14 2.74 1.92 1.66 1.38 1.97 2.28 1.71 1.02 0.91 1.38 0.00 0.69 0.01 2.07 FeOtot 7.74 9.62 28.63 36.27 23.74 31.88 30.56 30.75 12.08 33.72 9.67 26.72 33.09 28.84 9.76 22.85 10.61 10.23 9.51 33.81 MnO 0.17 0.88 0.85 0.85 0.63 0.83 0.82 0.74 0.44 0.89 0.36 0.61 0 70 0.93 0.41 0.61 0.88 0.37 0.35 0.79 MgO 1.60 9.12 7.41 9.91 5.62 8.40 7.48 9.68 9.80 9.26 10.64 6.00 9.51 10.88 10.06 8.55 10.26 10.51 10.56 8.19 Cao 1.89 23.80 4.89 3.60 5.78 3.39 5.30 10.64 27.85 6.90 30.52 12.38 5.20 13.37 31.38 18.65 33.28 31.87 33.84 4.70 Na20 3.53 0.23 1.71 1.15 0.99 0.34 0.98 0.27 0.89 1.20 0.62 0.32 0.78 0.12 0.47 0.18 0.02 0.02 0.04 0.26 K,O 4.13 0.04 0.87 0.34 2.17 1.23 0.99 0.40 0.23 0.16 0.02 0.58 0.47 0.12 0.01 0.47 0.01 0.01 0.02 0.34

Cr20 1 0.00 0.00 0.03 0.00 0.00 0.00 0.00 0.04 0.00 0.02 0.03 0.02 0.02 0.02 0.01 0.03 0.01 0.01 0.03 0.01 Total 81.00 63.67 63.42 62.39 60.20 59.30 59.20 58.96 58.79 58.50 58.44 57.53 57.29 57.23 56.35 56.31 55.14 54.56 54.47 54.47

s; 1.74 0.61 0.88 0.49 1.05 0.63 0.61 0.29 0.35 0.30 0.28 0.40 0.38 0.12 0.21 0.24 om 0.05 om 0.29 Tl 0.55 0.00 0.02 0.01 0.02 0.04 0.06 0.01 0.01 0.02 0.00 0.15 0.01 0.01 0.00 om 000 0.00 000 0.02 AI 0.59 0.62 0.32 0.18 0.35 0.25 0.22 0.15 0.12 0.11 0.14 0.19 0.14 0.08 0.07 0.11 om 0.05 000 0.18 Fetot 0.31 0.46 1.47 1.93 1.29 1.80 1.72 1.71 0.62 1.91 0.50 1.57 1.91 1.64 0.52 1.31 0.58 0.57 0.53 2.10 Mo 0.01 0.04 0.04 0.05 0.03 0.05 0.05 0.04 0.02 0.05 0.02 0.04 0.04 0.05 0.02 OM O.M 0.02 0.02 0.05 Mg 0.11 0.78 0.68 0.94 0.54 0.84 0.75 0.96 0.90 0.93 0.97 0.63 0.98 1.10 0.96 OB7 1.01 l.M 1M 0.91 Ca 0.10 1.46 0.32 0.24 0.40 0.24 0.38 0.76 1.84 0.50 2.01 0.93 0.38 0.97 2.15 1.37 2.35 2.26 2.~ 0.37 Na 0.33 0.03 0.20 0.14 0.12 0.04 0.13 0.03 0.11 0.16 0.07 0.04 0.10 0.02 0.06 oro 0.00 0.00 0.01 0.04 K 0.25 0.00 0.07 0.03 0.18 0.11 0.08 0.03 O.Q2 0.01 0.00 0.05 0.04 0.01 0.00 OM ~00 0.00 om 0.03

Wo 11.13 54.40 13.12 8.70 18.27 9.44 14.43 25.01 55.38 16.62 58.51 32.77 13.23 29.68 60.45 42.35 61.84 60.99 62.86 12.91 13.11 29.01 27.66 33.33 24.72 32.55 28.35 3166 27.12 31.04 28 38 22.10 33.66 33.61 26.97 27.01 26.53 27.99 27.29 31.31 N U"' '"Fs 38.14 15.64 50.93 52.95 51.34 56.30 52.39 42.19 14.30 47.11 10.96 43.60 49.52 36.24 10.94 29.90 11.56 10.95 9.71 54.49 U"' Sample Sample A9-a -1 Mineral: Feldspar (Oo=S) 11.1 Comment A. A. A. A. A. A. A. A. A. A. A. A. A. A. A. A. A. A. A. A. C" SiO, 54.14 49.64 57.94 46.77 55.90 56.75 48.89 44.02 45.40 45.60 47.58 46.61 48.00 47.26 49.18 49.11 45.88 48.25 49.12 46.64 ;;- Ti0 2 0.02 0.00 0.00 0.02 0.00 0.03 0.03 0.02 0.00 0.01 0.00 0.01 0.00 0.00 0.00 0.00 0.01 0.01 0.00 0.00 !=' AI203 35.50 32.19 35.60 34.40 35.60 34.56 36.02 33.32 37.11 37.74 35.09 34.39 29.90 36.96 37.85 30.37 23.49 26.93 26.12 28.97 N

Fe01ot 0.33 0.47 0.20 0.34 0.32 0.36 0.30 0.34 0.25 0.33 0.43 0.24 0.31 0.36 0.35 0.20 0.30 0.13 0.25 0.22 MnO 0.01 0.02 0.00 0.02 0.01 0.02 0.00 0.03 0.00 0.01 0.02 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.01 0.01 () MgO 0.13 0.84 0.23 0.38 0.29 0.68 0.26 0.18 0.28 0 0.60 0.37 0.72 0.49 0.29 0.31 0.27 0.29 0.23 0.30 0.24 ::J CaO 0.05 0.09 0.10 0.07 0.01 0.13 0.00 0.09 0.03 0.00 0.10 0.05 0.09 0.05 0.07 0.13 0.13 0.11 0.15 0.07 :::!. Na,p 0.10 0.08 0.07 0.07 0.31 0.07 0.06 1.92 0.07 1.07 3.46 0.94 0.24 3.61 6.45 6.15 6.04 4.99 ::J 0.09 0.08 c K20 0.05 0.95 0.08 0.76 0.09 0.75 0.46 0.11 0.21 0.12 0.73 0.66 0.44 0.20 0.12 0.09 0.60 0.09 0.21 0.16 ro Cr20 3 0.05 0.07 0.00 0.04 0.01 0.05 0.04 0.03 0.01 0.00 0.05 0.00 0.01 0.00 0.02 0.04 0.00 0.01 0.02 0.02 a. Total 90.38 84.35 94.22 83.09 92.62 93.44 86.29 80.26 83.39 84.18 84.75 83.34 82.47 86.04 88.12 83.79 77.16 81.86 82.20 81.32

51 2.57 2.66 2.58 2.60 2.59 2.63 2.59 2.63 2.58 2.55 2.64 2.65 2.75 2.57 2.58 2.77 2.90 2.81 2.84 2.78 Tl 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 AI 2.38 2.16 2.37 2.26 2.32 2.22 2.31 2.11 2.35 2.40 2.22 2.16 1.83 2.28 2.34 1.83 1.39 1.57 1.52 1.70 Fe tot 0.02 0.02 0.01 0.02 0.01 0.02 0.01 0.02 0.01 0.01 0.02 0.01 0.01 0.02 0.02 0.01 0.01 0.01 0.01 0.01 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0 00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mg 0.01 0.07 0.02 0.05 0.03 0.06 0.04 0.03 0.02 0.02 0.05 0.02 0.02 0.02 0.02 0.02 0.02 0.01 0.02 0.02 Ca 0.00 0.01 0.01 0.00 0.00 0.01 0.00 0.01 0.00 0.00 0.01 0.00 0.01 0.00 0.00 0.01 0 01 0.01 0.01 0.00 Na 0.01 0.01 0.01 0.01 0.03 0.01 0.01 0.20 0.01 0.01 0.01 0.11 0.35 0.10 0.02 0.36 0.63 0.59 0.58 0.48 K 0.00 0.07 0.01 0.05 0.01 0.05 0.03 0.01 0.01 0.01 0.05 0.04 0.03 0.01 0.01 0.01 0.04 0.01 0.01 0.01

o, 20.49 82.81 29.59 82.15 15.80 77.67 83.46 3.54 56.45 49.67 79.32 28.35 7.62 11.97 22.08 1.58 5.71 0.94 2.21 2.05 Ab 62.29 10.60 39.35 11.50 82.72 11.02 16.54 94.02 36.77 50.33 11.56 69.85 91.07 85.51 67.11 96.50 93.25 98.09 96.47 97.20 An 17.21 6.59 31.06 6.35 1.47 11.31 0.00 2.44 6.77 0.00 9.13 1.80 1.31 2.51 10.82 1.92 1.04 0.97 1.32 0.75

Mineral: Pyroxene (0=6) Comment H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. Si02 38.26 36.01 25.36 16.58 14.12 5.35 4.74 5.27 2.53 0.74 1.12 5.16 3.35 1.01 2.51 9.14 1.97 1.40 1.70 0.04 Ti02 20.93 1.47 0.06 0.00 0.02 0.43 0.01 0.00 0.04 2.25 0.08 0.00 1.78 7.22 0.04 0.65 0.01 14.54 0.18 0.04 AI203 12.28 10.40 12.35 10.02 8.20 4.13 1.46 1.86 0.98 0.28 0.39 2.91 1.57 0.41 1.53 4.38 0.75 0.72 1.11 0.03 FeOtot 2.67 18.29 18.73 31.49 32.10 37.01 38.64 35.80 36.89 39.61 40.73 11.04 33.79 28.86 11.40 29.47 10.87 24.88 36.71 9.97 MnO 0.08 0.48 0.36 0.76 0.54 0.72 0.84 0.64 0.54 0.93 0.81 0.74 0.66 0.74 0.36 0.56 0.56 0.62 0.73 0.36 MgO 0.84 4.10 4.93 7.47 9.01 10.04 10.45 11.55 12.51 11.45 12.00 10.52 11.70 8.59 10.66 7.59 10.36 6.55 10.60 10.12 cao 1.91 3.18 5.44 1.94 2.08 3.37 3.66 3.60 5.16 3.54 3.29 27.07 4.57 10.11 29.54 2.81 30.87 6.16 3.00 33.46

Na 20 5.91 7.23 3.40 2.17 0.42 0.15 1.11 0.71 0.48 0.09 0.09 0.54 0.13 0.22 0.33 1.48 0.37 0.20 0.19 0.03 K,O 1.27 0.30 0.13 0.03 0.35 0.09 0.02 0.36 0.01 0.07 0.14 0.04 0.19 0.04 0.01 0.06 0.00 0.06 0.02 0.01

Cr201 0.06 0.01 0.01 0.02 0.04 0.10 0.03 0.02 0.02 0.03 0.03 0.00 0.06 0.03 0.01 0.03 0.01 0.03 0.00 0.00 Total 84.21 81.47 70.77 70.48 66.88 61.39 60.96 59.81 59.16 58.99 58.68 58.02 57.80 57.23 56.39 56.17 55.77 55.16 54.24 54.06

51 1.76 1.62 1.34 0.91 0.83 0.35 0.31 0.35 0.17 0.05 0.08 0.32 0.23 0.07 0.16 0.64 0.13 0.11 0.13 0.00 Tl 0.72 0.05 0.00 0.00 0.00 0.02 0.00 0.00 0.00 0.12 0.00 0.00 0.09 0.39 0.00 0.03 0.00 0.85 0.01 0.00 AI 0.66 0.55 0.77 0.65 0.57 0.32 0.11 0.14 0.08 0.02 0.03 0.21 0.13 0.03 0.12 0.36 0.06 0.07 0.10 0.00

Fetot 0.10 0.69 0.83 1.45 1.58 2.02 2.11 1.97 2.05 2.29 2.34 0.57 1.94 1.73 0.61 1.72 0.59 1.62 2.28 0.56 Mn 0.00 0.02 0.02 0.04 0.03 0.04 0.05 0.04 0.03 0.05 0.05 0.04 0.04 0.04 0.02 0.03 0.03 0.04 0.05 0.02 Mg 0.06 0.27 0.39 0.61 0.79 0.98 1.02 1.13 1.24 1.18 1.23 0.98 1.20 0.92 1.02 0.79 1.00 0.76 1.17 1.01 ca 0.09 0.15 0.31 0.11 0.13 0.24 0.26 0.25 0.37 0.26 0.24 1.81 0.34 0.78 2.03 0.21 2.15 0.51 0.24 2.40 Na 0.53 0.63 0.35 0.23 0.05 0.02 0.14 0.09 0.06 0.01 0.01 0.07 0.02 0.03 0.04 0.20 0.05 0.03 0.03 0.00 K 0.07 0.02 0.01 0.00 0.03 0.01 0.00 0.03 0.00 0.01 0.01 0.00 0.02 0.00 0.00 0.01 0.00 0.01 0.00 0.00

Wo 11.86 8.90 16.87 5.13 5.62 8.44 8.62 8.62 11.75 8.46 7.75 54.60 11.20 25.40 57.38 8.10 59.09 19.11 7.77 63.04 N 7.26 15.97 21.27 27.48 33.87 34.98 38.49 38.06 39.35 39.89 28.81 30.43 27.59 28.28 38.23 26.53 U"' ,,En 34.24 39.64 29.53 30.03 en 14.44 38.50 42.78 57.01 58.45 55.90 52.41 49.82 46.63 53.10 52.52 13.91 48.34 43.56 12.65 53.76 12.04 51.49 53.11 10.32 Sample Sample A14-b -1 Mineral: Feldspar (0"'8) Ill C" Comment A. A. A. A. A. A. A. A. A. A. A. A. A. A. A. A. A. A. Si01 48.02 45.25 46.59 47.61 48.21 48.33 47.53 47.66 48.81 48.77 47.80 50.09 49.11 49.00 48.75 49.21 48.63 49.88 52.45 54.06 nr

Ti0 2 0.43 0.00 0.00 0.01 0.00 0.00 0.00 0.02 0.00 0.37 0.00 0.02 0.01 0.00 0.00 0.01 0.01 0.00 0.01 0.00 0 AI201 27.50 33.95 35.33 32.64 32.23 31.03 35.21 36.25 32.19 30.03 36.77 29.39 33.20 33.32 35.78 34.26 36.88 33.89 32.79 31.54 N

Fe0,0, 0.78 1.96 0.44 0.77 0.47 0.72 0.47 0.46 0.62 0.88 0.41 1.14 0.56 0.53 0.41 0.48 0.47 0.77 0.46 0.43 MnO 0.01 0.05 0.01 0.02 0.02 0.00 0.00 0.00 0.00 0.02 n 0.00 0.02 0.00 0.00 0.01 0.02 0.01 0.02 0.00 0.00 0 MgO 1.97 0.88 0.42 1.06 1.02 1.53 0.59 0.41 1.34 1.83 0.45 1.71 1.17 1.22 0.50 1.02 0.43 1.23 0.40 0.37 :::::1 CaO 0.26 0.42 0.07 0.11 0.13 0.22 0.08 0.05 0.13 0.29 0.04 0.24 0.10 0.18 0.13 0.13 0.17 0.20 0.12 0.10 !:!: Na 0 0.11 :::::1 2 0.13 0.39 0.07 0.21 0.07 0.08 0.11 0.05 0.08 0.09 0.47 0.06 0.06 0.48 0.05 0.60 0.06 2.63 3.55 c K,o 2.98 0.40 0.17 1.26 1.39 1.97 0.41 0.16 1.76 2.37 0.16 2.25 1.44 1.51 0.27 1.12 0.15 1.43 0.22 0.16 I'll Cr201 0.29 0.05 0.01 0.14 0.07 0.13 0.03 0.02 0.12 0.18 0.02 0.17 0.11 0.13 0.02 0.11 0.06 0.13 0.00 0.03 a. Total 82.35 83.09 83.43 83.69 83.75 84.00 84.40 85.14 85.02 84.80 85.76 85.50 85.76 85.95 86.35 86.41 87.41 87.61 89.08 90.24

Si 2.70 2.53 2.58 2.64 2.66 2.66 2.61 2.59 2.66 2.66 2.58 2.71 2.65 2.64 2.61 2.64 2.57 2.64 2.69 2.72 Ti 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 AI 1.82 2.24 2.31 2.13 2.10 2.01 2.28 2.32 2.07 1.93 2.34 1.87 2.11 2.11 2.26 2.16 2.29 2.11 1.98 1.87 Fe tot 0.04 0.09 0.02 0.04 0.02 0.03 0.02 0.02 0.03 0.04 0.02 0.05 0.03 0.02 0.02 0.02 0.02 0.03 0.02 0.02 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mg 0.17 0.07 0.03 0.09 0.08 0.13 0.05 0.03 0.11 0.15 0.04 0.14 0.09 0.10 0.04 0.08 0.03 0.10 0.03 0.03 Ca 0.02 0.03 0.00 0.01 0.01 0.01 0.00 0.00 0.01 0.02 0.00 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 Na 0.01 0.01 0.04 0.01 0.02 0.01 0.01 0.01 0.01 0.01 0.01 0.05 0.01 0.01 0.05 0.01 0.06 0.01 0.26 0.35 K 0.21 0.03 0.01 0.09 0.10 0.14 0.03 0.01 0.12 0.17 0.01 0.16 0.10 0.10 0.02 0.08 0.01 0.10 0.01 0.01

Or 88.54 42.09 20.69 86.37 76.44 87.12 68.47 43.34 90.48 86.65 48.43 71.07 89.15 86.17 24.35 85.81 12.45 84.66 5.10 2.84 Ab 4.97 20.79 72.15 7.29 17.55 4.70 20.31 45.28 3.91 4.45 41.40 22.56 5.65 5.20 65.80 5.82 75.70 5.40 92.57 95.67 An 6.49 37.12 7.16 6.33 6.00 8.17 11.22 11.37 5.61 8.90 10.17 6.37 5.20 8.63 9.85 8.37 11.85 9.94 2.33 1.49

Mineral: Pyroxene (0=6) Comment H.A. HA H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. H.A. SiOz 15.06 41.85 23.90 25.08 16.29 13.01 9.19 12.82 2.05 2.29 1.23 1.07 1.20 1.45 0.79 2.31 0.27 5.83 0.76 0.64 Ti02 54.57 0.12 0.07 5.68 0.05 0.10 0.07 0.21 0.27 0.09 0.03 0.03 0.02 0.16 0.01 0.09 0.02 0.13 0.03 0.02 AI203 6.50 12.36 7.83 9.49 7.28 3.35 2.57 5.39 0.99 0.77 0.03 0.02 0.04 0.45 0.02 0.81 0.02 2.02 0.11 0.03 FeOtot 2.73 10.62 28.69 20.24 35.18 37.84 34.96 27.96 40.74 42.67 36.85 34.94 35.60 41.98 35.80 42.13 31.41 35.57 34.03 29.27 MnO 0.12 0.32 0.80 0.45 1.26 1.10 0.95 0.55 1.06 1.23 0.55 0.44 0.48 1.48 0.58 1.69 0.54 0.84 0.64 0.48 MgO 0.56 2.10 4.99 4.54 7.98 8.98 8.45 5.55 8.68 8.36 17.25 17.78 17.15 7.72 16.83 6.07 22.19 5.79 16.95 19.93 CaO 3.56 6.23 2.48 2.44 1.85 2.02 6.11 7.01 5.02 3.22 2.31 3.84 3.18 4.11 3.32 3.43 2.43 5.48 4.15 6.16

Na 20 0.64 4.97 3.60 3.88 1.73 0.61 1.50 0.31 0.25 0.44 0.07 0.07 0.09 0.20 0.06 0.25 0.07 0.46 0.14 0.14 K,O 1.83 3.36 0.13 0.48 0.06 1.53 0.16 1.57 0.06 0.04 0.03 0.01 0.02 0.19 0.03 0.28 0.02 0.79 0.05 0.03

Cr20 3 0.07 0.00 0.02 0.07 0.04 0.01 0.02 0.04 0.02 0.01 0.01 0.03 0.00 0.00 0.00 0.01 0.00 0.01 0.00 0.02 Total 85.64 81.93 72.51 72.35 71.72 68.55 63.98 61.41 59.14 59.12 58.36 58.23 57.78 57.74 57.44 57.07 56.97 56.92 56.86 56.72

Si 0.81 1.87 1.27 1.33 0.90 0.76 0.57 0.83 0.14 0.16 0.08 0.07 0.08 0.11 0.05 0.17 0.02 0.42 0.05 0.04 Ti 2.21 0.00 0.00 0.23 0.00 0.00 0.00 0.01 0.01 0.00 0.00 0.00 0.00 0.01 0.00 0.01 0.00 0.01 0.00 0.00 AI 0.41 0.65 0.49 0.59 0.47 0.23 0.19 0.41 0.08 0.06 0.00 o.oo 0.00 0.04 0.00 0.07 0.00 0.17 0.01 0.00 Fetot 0.12 0.40 1.28 0.90 1.62 1.85 1.81 1.52 2.38 2.51 2.02 1.90 1.96 2.55 1.99 2.63 1.67 2.16 1.90 1.57 Mn 0.01 0.01 0.04 0.02 0.06 0.05 0.05 0.03 0.06 0.07 0.03 0.02 0.03 0.09 0.03 0.11 0.03 0.05 0.04 0.03 Mg 0.04 0.14 0.40 0.36 0.65 0.78 0.78 0.54 0.90 0.88 1.69 1.72 1.69 0.84 1.67 0.68 2.10 0.63 1.69 1.91 ca 0.20 0.30 0.14 0.14 0.11 0.13 0.41 0.49 0.38 0.24 0.16 0.27 0.22 0.32 0.24 0.27 0.17 0.43 0.30 0.42 Na 0.07 0.43 0.37 0.40 0.18 0.07 0.18 0.04 0.03 0.06 0.01 0.01 0.01 0.03 0.01 0.04 0.01 0.06 0.02 0.02 0.13 0.19 0.01 0.03 0.00 0.11 0.01 0.13 0.01 0.00 0.00 0.00 000 0.02 0.00 0.03 0.00 0.07 0.00 0.00

Wo 43.83 8.08 6.84 N 23.48 6.80 7.88 4.61 5.04 14.51 20.75 12.38 8.10 4.98 10.58 7.19 9.38 4.83 15.39 8.94 12.35 V'l En 9.59 11.01 19.04 20.39 27.66 31.19 27.92 22.86 29.80 29.27 51.71 52.04 51.37 27.66 50.73 23.09 61.44 22.62 50.83 55.59 -....J Fs 32.32 31.62 56.30 49.07 59.94 61.02 51.13 54.74 56.70 60.63 43.04 39.62 41.44 60.82 41.84 66.30 33.48 59.65 39.68 31.55 Sample Sample Bl Sample Sample B4 -1 Mineral: Feldspar (0=8) Mineral: Feldspar {0=8) 11.1 Comment Core Core Core Core Core Rim Rim Rim Rim Rim Comment A. A. ~ A. A. A. A. A. A. C"

Si02 51.90 52.12 52.77 52.05 51.28 52.88 51.40 53.64 54.34 53.10 5i02 53.90 54.51 54.68 ~~ 54.05 54.27 53.49 54.71 53.48 55.51 iD Ti02 0.05 0.04 0.05 0.05 0.04 0.09 0.02 0.06 0.07 0.08 Ti02 0.12 0.09 0.13 0.10 0.10 0.11 0.10 0.13 0.10 0.12 c AI203 27.57 27.14 27.53 26.98 27.09 26.94 27.44 26.59 26.76 26.89 AI20, 26.49 26.29 25.88 m~ 25.98 26.11 26.63 25.49 26.17 24.84 w Fe0ro1 0.53 0.51 0.48 0.69 0.52 2.00 0.73 0.47 0.51 0.62 Fe0101 0.74 0.84 0.96 0~ 0.99 0.81 0.72 0.92 1.00 0.92 MnO D.OO 0.03 0.01 0.03 0.02 0.00 D.OO 0.00 0.00 0.00 MnD 0.00 0.00 0.03 0.01 0.02 0.01 0.02 D.OO 0.01 D.OO MgO 0.16 0.08 0.17 0.07 0.12 0.78 0.07 0.03 0.08 0.06 MgD 0.21 0.15 0.14 0.22 0.14 0.1R 017 0.09 0.19 0.08 s: CaD 14.30 14.08 13.10 14.02 14.90 10.92 12.31 8.99 8.53 10.08 CaD 12.08 11.36 10.69 11.50 11.22 11.14 11.68 10.51 11.56 9.84 ::r I'D Na 20 3.78 3.92 3.78 3.93 3.79 5.02 7.01 7 94 7.38 5.76 Na20 5.04 5.14 5.31 4.99 5.13 5.07 4.85 5.55 5.02 5.79 Q,)'"' K,D 0.20 0.25 0.22 0.27 0.24 0.62 0.22 0.63 0.62 0.54 K,D 0.31 0.42 0.56 0.~ 0.43 0.40 0.33 0.56 0.33 0.65 Cr20 D.OO 0.01 0.00 0.00 0.00 0.00 Cr 0 0.02 0.00 0.00 0.00 0.00 0.00 0.00 n 3 0.00 0.01 0.00 0.02 2 3 0.00 0.01 0.01 :::T Total 98.49 98.18 98.11 98.09 98.00 99.25 99.20 98.36 98.29 97.15 Total 98.92 98.85 98.42 •n 98.17 98.12 98.01 97.98 97.94 97.79 I'D 3 s; 2.40 2.42 2.45 2.42 2.39 2.41 2.30 2.41 2.45 2.46 ~ ~ 2.50 2.51 2.49 2.50 2.50 2.47 2.52 2.47 2.56 ;:;· r; 0.00 0.00 0.00 0.00 0.00 0.00 ODD 0.00 0.00 0.00 n ~ o.oo 0.00 0.00 0.00 0.00 D.OO 0.00 0.00 0.00 Q,) AI 1.50 lAB 1.51 1.48 1.49 1.45 1.45 1.41 1.42 1.47 ~~ 1.42 1.40 1.42 1.41 1.42 1.45 1.38 1.43 1.35 M Q,) Few, 0.02 ODl 0.02 0.03 0.02 0.08 O.D3 0.02 0.02 OD2 Fe, 01 0.03 0.03 0.04 O.D3 0.04 O.D3 0.03 0.04 0.04 0.04 ::J Q,) Mn 0.00 000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 0.00 0.00 D.OO 0.00 0.00 0.00 Mg 0.01 0~1 0.01 0.00 0.01 0.05 0.00 0.00 0.01 000 Mg 0.01 0.01 0.01 0.02 0.01 0.01 0.01 0.01 0.01 0.01 -

Mineral: Pyroxene (0=6) Mineral: Pyroxene (0=6) -< Comment Core Core Core Core Core Rim Rim Rim Rim Rim Comment A. A. ~ A. A. A. A. A A. A. 3 Si0 2 47.81 45.95 47.41 47.23 46.60 46.61 44.41 44.06 44.66 44.25 5i0 2 34.81 29.70 ms 38.18 32.30 29.29 31.03 36.68 31.24 31.28 ::J Ti0 2 0.52 0.84 0.49 0.51 0.23 0.42 0.78 0.78 0.78 0.82 Ti02 3.71 2.77 0.06 1.40 0.16 3.03 0.15 0.06 0.07 0.05 I'D AI203 1.56 1.23 1.57 1.45 1.50 0.82 1.30 0.95 1.16 1.03 AIP1 17.33 17.32 ~~ 16.06 16.00 16.17 17.37 17.45 17.16 17.55 0::

, iii' Fe0,0 8.99 13.64 8.60 10.72 7.53 17.38 15.35 20.21 16.44 18.63 Fe0101 23.54 27.64 m~ 19.80 27.20 23.40 27.47 20.26 25.43 24.85 MnO 0.22 0.33 0.26 0.24 0.24 0.42 0.31 0.39 0.30 0.39 MnO 0.10 0.10 om D.DS 0.09 0.11 0.08 0.07 0.11 0.10 =i' MgD 16.39 16.52 16.70 17.00 17.70 13.32 13.49 12.34 13.09 12.15 MgO 6.77 7.99 8M 5.07 8.12 6.61 7.99 6.10 7.16 7.27 0 CaD 19.23 16.30 18.96 16.16 18.28 14.24 17.09 14.08 16.32 15.36 CaO 1.39 0.90 0.72 1.35 0.67 5.29 0.52 1.70 1.32 1.19 3 Na 20 0.19 0.18 0.20 0.18 0.20 0.08 0.22 0.19 0.21 0.18 Nap 0.94 0.40 0.39 0.86 0.37 0.97 0.26 1.11 0.63 0.51 n K,O D.OO 0.01 D.OO O.Q2 0.01 0.01 0.01 0.00 0.00 0.01 K10 1.32 0.10 D~ 2.40 0.12 0.17 0.06 0.86 0.07 0.07 0 I'D Cr 20 3 0.14 0.03 0.22 0.09 0.75 0.01 0.07 0.02 0.03 0.01 Cr20 3 0.08 0.05 O.M 0.07 0.08 0.07 0.08 0.05 0.08 0.10 '"' Total 95.05 95.03 94.41 93.60 93.04 93.31 93.03 93.02 92.99 92.83 Total 89.99 86.97 85.27 85.11 85.11 85.01 84.34 83.27 82.97 CJ -~ Vl Q,) s; 1.85 1.80 1.84 1.86 1.83 1.90 1.80 1.82 1.82 1.83 s; 1.50 1.33 1.37 1.72 1.47 1.33 1.41 1.66 1.45 1.45 3 r; 0.02 0.02 0.01 0.02 0.01 0.01 0.02 0.02 0.02 0.03 T1 0.12 0.09 0.00 0.05 0.01 0.10 0.01 0.00 0.00 0.00 '0 AI 0.07 0.06 0.07 0.07 0.07 0.04 0.06 0.05 0.06 0.05 AI 0.88 0.92 0.83 0.85 0.86 0.87 0.93 0.93 0.94 0.96 iii' Fe tot 0.29 0.45 0.28 0.35 0.25 0.59 0.52 0.70 0.56 0.64 Fe rot 0.85 1.04 1.13 0.75 1.04 0.89 1.05 0.77 0.99 D.96 Vl Mn 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 Mn 0.00 0.00 D.OO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mg 0.95 0.96 0.97 1.00 1.03 0.81 0.82 0.76 0.80 0.75 Mg 0.43 0.53 0.58 0.34 DSS 0.45 0.54 0.41 0.49 0.50 Ca 0.80 0.68 0.79 0.68 0.77 0.62 0.74 0.62 0.71 0.68 Ca 0.06 0.04 0.03 0.07 0.03 0.26 0.03 0.08 0.07 0.06 Na 0.01 0.01 0.02 0.01 0.02 0.01 0.02 0.02 0.02 0.01 Na 0.08 0.03 0.03 0.08 0.03 0.09 0.02 0.10 0.06 0.05 K 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 K 0.07 0.01 0.01 0.14 0.01 0.01 0.00 0.05 0.00 0.00

Wo 38.89 32.44 38.41 33.28 37.14 30.52 35.47 29.76 34.22 32.59 Wo 4.50 2.65 1.99 5.25 2.00 15.53 1.57 6.03 4.13 3.79 En 46.12 45.75 47.08 48.71 50.05 39.72 38.96 36.30 38.19 35.88 En 30.47 32.79 33.17 27.43 33.69 27.01 33.53 30.10 31.14 32.20 N ,, 14.30 21.16 13.77 17.34 12.07 29.45 24.75 33.21 26.80 30.84 ,, 59.53 62.42 62.90 61.27 62.32 52.30 63.49 56.75 61.17 61.07 VI 00 Sample Sample 85 Sample Sample Bll-c -f Mineral: Feldspar (0=8) Mineral: Feldspar (0=8) 11.1 Comment A A. A. A. A. Comment H.A. H.A. H.A. H.A. H.A. H.A. H.A. tr

Si01 72.49 53.75 75.18 52.71 56.04 St02 64.46 54.94 53.05 53.66 50.00 39.54 39.12 tD Ti0 0.52 0.07 2 0.13 0.65 0.04 Ti01 0.00 0.03 0.01 0.02 0.03 0.02 0.00 c Al20 3 13.67 23.14 9.39 14.94 19.65 Al20 3 17.66 26.39 19.84 20.73 16.68 14.36 11.84 i.u

Fe0 101 2.08 3.04 4.11 11.87 0.29 Fe0101 0.34 0.99 3.15 1.79 0.56 0.72 0.72 MnO 0.01 0.03 0.00 0.02 0.06 MnO 0.07 0.00 0.22 0.10 0.22 0.47 0.73 n MgO 0.52 0.70 1.11 2.58 0.13 MgO 0.08 0.56 1.14 0.76 0.25 0.33 0.40 0 ::J CaO 3.56 8.21 2.35 0.75 7.04 CaO 3.74 8.43 9.03 9.44 14.37 22.68 22.82 ~. Na 0 2 4.61 5.69 2.68 0.64 8.24 Na20 11.90 5.14 7.17 6.94 7.84 5.75 6.18 ::J K,O 0.29 1.10 0.15 7.24 0.13 K,O 0.03 1.02 0.40 0.21 0.15 0.13 0.06 r:::: (!) Cr 0 0.02 0.02 2 3 0.00 0.04 0.01 Crz0 3 0.00 0.02 0.03 0.00 0.00 0.00 0.03 a. Total 97.80 95.78 95.18 91.68 91.64 Total 98.29 97.61 94.06 93.71 90.21 84.11 81.96

Si 3.46 2.54 3.78 2.75 2.71 Si 2.86 2.54 2.52 2.56 2.46 2.11 2.14 Ti 0.02 0.00 0.00 0.03 0.00 T' 0.00 0.00 0.00 0.00 0.00 0.00 0.00 AI 0.77 1.29 0.56 0.92 1.12 AI 0.92 1.44 1.11 1.17 0.97 0.90 0.76 Fe tot 0.08 0.12 0.17 0.52 0.01 Fe,ot 0.01 0.04 0.13 0.07 0.02 0.03 0.03 Mn 0.00 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.01 0.00 0.01 0.02 0.03 Mg 0.04 0.05 0.08 0.20 0.01 Mg 0.01 0.04 0.08 0.05 0.02 0.03 0.03 Ca 0.18 0.42 0.13 0.04 0.36 Ca 0.18 0.42 0.46 0.48 0.76 1.30 1.34 Na 0.43 0.52 0.26 0.06 0.77 Na 1.02 0.46 0.66 0.64 0.75 0.60 0.66 K 0.02 0.07 0.01 0.48 0.01 K 0.00 0.06 0.02 0.01 0.01 0.01 0.00

Or 2.82 6.61 2.42 81.88 0.70 Or 0.14 6.41 2.12 1.12 0.62 0.47 0.21 Ab 68.11 51.96 65.73 11.00 67.45 Ab 85.08 49.09 57.71 56.45 49.37 31.30 32.82 An 29.07 41.43 31.85 7.12 31.85 An 14.78 44.49 40.17 42.43 50.01 68.23 66.97

Mineral: Pyroxene (0=6) Mineral; Pyroxene (0=6) Comment A. A. A. A. A. A. A. A. A. A. Comment A. A. A. A. A. A. A. A. A. A.

Si02 49.00 40.74 31.09 30.68 29.79 30.46 41.79 29.44 20.91 35.63 Si02 44.89 46.18 44.69 44.92 43.76 33.84 31.27 31.05 30.89 31.39

Ti02 0.04 0.22 0.08 0.17 0.08 1.02 0.09 0.08 0.05 0.05 Ti0 2 3.25 3.88 1.82 1.88 2.38 2.91 0.55 0.08 0.08 0.48

AI20J 26.62 18.86 16.64 17.47 15.89 14.60 16.26 16.45 13.03 14.69 Alpl 18.58 17.80 18.57 18.93 17.74 14.36 14.08 14.09 14.08 14.12

FeD rot 7.45 16.33 28.19 29.41 28.41 26.06 11.65 27.69 21.31 13.44 Fe01ot 13.18 11.60 14.51 13.20 15.60 24.56 28.09 28.59 28.56 27.50 MnO 0.03 0.02 0.05 0.04 0.03 0.03 0.08 0.06 0.46 0.01 MnO 0.04 0.03 0.02 0.04 0.03 0.03 0.04 0.05 0.05 0.03 MgO 1.79 3.73 12.93 7.25 12.14 6.87 3.03 11.93 7.20 7.05 MgO 5.73 4.76 6.03 6.02 6.73 11.64 13.93 13.77 13.72 13.32 CaD 2.46 5.69 0.32 1.65 0.27 6.19 8.47 0.30 14.30 0.45 CaD 4.43 4.68 4.43 4.66 3.32 0.77 0.44 0.38 0.34 0.39

Na20 3.69 2.92 0.11 0.34 0.10 1.03 4.62 0.07 0.23 2.73 Na20 3.59 3.45 3.60 3.70 3.19 0.79 0.10 0.10 0.09 0.19 K,O 0.20 1.40 0.06 0.79 0.09 0.26 0.24 0.08 0.30 0.93 K,O 0.96 2.20 0.63 0.48 0.99 0.52 0.07 0.09 0.08 0.11

Cr20l 0.02 0.04 0.12 0.06 0.08 0.09 0.04 0.12 0.02 0.03 Cr1 03 0.03 0.02 0.01 0.02 0.01 0.08 0.14 0.09 0.08 0.06 Total 91.30 89.95 89.59 87.86 86.88 86.61 86.27 86.22 77.81 75.01 Total 94.68 94.60 94.31 93.85 93.75 89.50 88.71 88.29 87.97 87.59

Si 1.97 1.70 1.32 1.36 1.31 1.36 1.78 1.30 1.03 1.74 Si 1.76 1.82 1.76 1.77 1.74 1.44 1.34 1.34 1.33 1.36 Ti 0.00 0.01 0.00 0.01 0.00 0.03 0.00 0.00 0.00 0.00 Ti 0.10 0.12 0.05 0.06 0.07 0.09 0.02 0.00 0.00 0.02 AI 1.26 0.93 0.83 0.91 0.82 0.77 0.82 0.86 0.75 0.85 AI 0.86 0.83 0.86 0.88 0.83 0.72 0.71 0.71 0.72 0.72 Feror 0.25 0.57 1.00 !.09 1.04 0.97 0.42 1.02 0.88 0.55 Fe tot 0.43 0.38 0.48 0.44 0.52 0.87 1.01 1.03 1.03 1.00 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mg 0.11 0.23 0.82 0.48 0.79 0.46 0.19 0.79 0.53 0.51 Mg 0.34 0.28 0.35 0.35 0.40 0.74 0.89 0.88 0.88 0.86 Ca 0.11 0.25 0.01 0.08 0.01 0.30 0.39 0.01 0.75 0.02 Ca 0.19 0.20 0.19 0.20 0.14 0.04 0.02 0.02 0.02 0.02 Na 0.29 0.24 0.01 0.03 0.01 0.09 0.38 0.01 0.02 0.26 Na 0.27 0.26 0.27 0.28 0.25 0.07 0.01 0.01 0.01 0.02 K 0.01 0.07 0.00 0.04 0.01 0.01 0.01 0.00 0.02 0.06 K 0.05 0.11 0.03 0.02 0.05 0.03 0.00 0.00 0.00 0.01

Wo 13.74 19.65 0.81 4.78 0.70 16.70 28.05 0.80 35.72 1.75 Wo 15.05 17.42 14.36 15.40 10.77 2.08 1.08 0.93 0.83 0.98 "-1 En 13.91 17.93 45.47 29.23 43.89 25.80 13.96 44.02 25.03 38.15 En 27.08 24.65 27.20 27.68 30.39 43.65 47.40 46.82 46.82 46.59 1.1'1 Fs 35.07 44.18 53.22 64.21 54.94 52.47 30.31 54.84 38.21 40.90 Fs 35.81 34.70 37.32 34.79 40.11 50.42 51.08 51.81 51.94 51.56 1.0 Sample Sample B13-b -1 Mineral: Feldspar (0=8) IIJ C" Comment A. A. A. A. A. A. A. A. A. A. A. A. A. A. A. ii) Si02 68.69 68.83 68.17 68.17 68.22 68.11 66.71 66.98 65.84 65.98 65.61 65.04 63.11 63.52 64.10 Ti02 0.01 0.01 0.00 0.00 0.01 0.00 0.05 0.02 0.04 0.34 0.01 0.02 1.88 0.31 0.54 c Al 20 3 19.01 18.73 18.50 18.93 18.66 18.90 19.63 19.06 18.44 18.50 18.11 18.41 17.79 17.43 16.76 w FeOtt>t 0.07 0.09 0.29 0.10 0.13 0.07 0.37 0.25 1.27 0.44 0.19 0.83 1.19 0.62 0.33 I MnO 0.00 0.02 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.00 0.00 0.01 0.02 0.00 0.01 n MgO 0.02 0.01 0.02 0.00 0.03 0.00 0.25 0.14 0.53 0.16 0.02 0.40 0.50 0.19 0.11 0 :::J CaO 0.00 0.08 0.07 0.00 0.01 0.03 0.09 0.17 0.14 0.18 0.12 0.10 0.16 0.06 0.08 !:!. Na 0 2 11.99 11.92 10.19 11.94 12.06 11.89 9.14 9.00 9.23 9.08 7.20 7.48 8.55 2.24 2.96 c:::J K,O 0.09 0.08 2.50 0.09 0.09 0.06 2.82 3.18 2.76 2.76 6.04 4.99 2.96 11.47 10.65 (!) Cr203 0.00 0 01 0.00 0.00 0.01 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 c.. Total 99.96 99.80 99.77 99.27 99.25 99.12 99.10 98.86 98.25 97.48 97.35 97.34 96.20 95.85 95.61

s, 300 3.01 3.01 2.99 3.00 3.00 2.98 3.00 2.97 3.00 3.01 2.98 2.93 3.05 3.08 Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.07 0.01 0.02 AI 0.98 0.97 0.96 0.98 0.97 0.98 1.03 1.01 0.98 0.99 0.98 1.00 0.97 0.99 0.95

Fetot 0.00 0.00 0.01 0.00 0.00 0.00 0.01 0.01 0.05 0.02 0.01 0.03 0.05 0.02 0.01 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mg 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.01 0.04 0.01 0.00 0.03 0.03 0.01 0.01 Ca 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.01 0.01 0.00 0.01 0.00 0.00 Na 1.01 101 0.87 1.02 1.03 1.01 0.79 0.78 0.81 0.80 0.64 0.67 0.77 0.21 0.28 K 0.01 0.00 0.14 0.01 0.01 0.00 0.16 0.18 0.16 0.16 0.35 0.29 0.18 0.70 0.65

o, 0.49 0.44 13.85 0.49 0.49 0.33 16.80 18.70 16.33 16.52 35.36 30.35 18.40 76.85 69.99 Ab 99.51 99.19 85.82 99.51 99.47 99.53 82.75 80.46 82.98 82.58 64.05 69.14 80.77 22.81 29.57 An 0.00 0.37 0.33 0.00 0.05 0.14 0.45 0.84 0.70 0.90 0.59 0.51 0.84 0.34 0.44

Mineral: Pyroxene (0=6) Comment A. A. A. A. A. A. A. A. A. A. Si02 32.49 32.32 31.57 31.34 31.32 30.88 30.56 29.93 29.97 28.55 TiOz 0.05 0.07 0.06 0.27 0.08 0.07 0.13 0.07 0.07 0.03 AI203 16.72 16.59 15.96 16.40 15.88 15.43 15.95 15.33 15.15 14.36 FeOtot 27.61 27.44 27.57 26.96 27.85 28.12 27.56 28.05 27.49 27.81 MnO 0.05 0.03 0.03 0.05 0.03 0.05 0.04 0.05 0.06 0.06 MgO 13.43 13.45 12.73 12.24 12.36 12.56 12.31 12.42 12.29 11.16 CaO 0.35 0.34 0.47 0.37 0.32 0.38 0.37 0.41 0.30 0.40

Na20 0.16 0.17 0.16 0.20 0.13 0.12 0.13 0.12 0.14 0.13 K,o 0.18 0.17 0.20 0.41 0.17 0.15 0.17 0.15 0.18 0.18

Cr20 3 0.04 0.03 0.01 0.06 0.03 0.03 0.05 0.01 0.03 0.02 Total 91.08 90.61 88.76 88.30 88.17 87.79 87.27 86.54 85.68 82.70

Si 1.35 1.35 1.35 1.35 1.35 1.34 1.33 1.32 1.33 1.32 Ti 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 AI 0.82 0.82 0.80 0.83 0.81 0.79 0.82 0.79 0.79 0.78 Fe tot 0.96 0.96 0.99 0.97 1.01 1.02 1.00 1.03 1.02 1.08 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mg 0.83 0.84 0.81 0.78 0.80 0.81 0.80 0.81 0.81 0.77 ca 0.02 0.02 0.02 0.02 0.01 0.02 0.02 0.02 0.01 0.02 Na 0.01 0.01 0.01 0.02 0.01 0.01 0.01 0.01 0.01 0.01 K 0.01 0.01 0.01 0.02 0.01 0.01 0.01 0.01 0.01 0.01

N Wo 0.87 0.85 1.20 0.97 0.83 0.97 0.97 1.06 0.79 1.09 (j) En 46.70 46.90 45.32 44.85 44.55 44.74 44.69 44.57 44.82 42.14 0 ,, 51.70 51.47 52.74 53.23 54.01 53.73 53.73 53.81 53.73 56.13 Sample Sample 813-c Sample Sample B15·a 0} Mineral: Feldspar (0=8) Mineral: Feldspar {0=8) Comment A. A. A. A. A. Comment A. A. A. A. A A A. A. A. C"

Si02 69.70 69.54 69.44 69.15 66.41 Si02 52.44 54.41 52.21 51.50 52.82 51.76 51.31 51.39 50.41 51.60 tD Ti02 0.00 0.03 0.01 0.02 0.04 Ti01 0.05 0.05 0.06 0.05 0.08 0.07 0.06 0.08 0.04 0.07 0 AI203 19.02 18.91 18.86 18.87 18.96 AI103 28.94 26.69 28.46 28.95 27.90 27.85 28.57 28.24 28.38 27.80 w fe0 101 0.12 0.11 0.07 0.16 2.23 Feo,.,, 0.77 1.55 0.81 0.80 0.72 0.90 0.71 0.73 0.75 0.71 MnO 0.00 0.03 0.00 0.00 0.02 MnO 0.00 0.02 0.00 0.00 0.03 0.01 0.03 0.02 0.02 0.01 () MgO 0.01 0.00 0.01 0.02 0.85 MgO 0.20 0.49 0.24 0.17 0.19 0.28 0.19 0.16 0.22 0.12 0 CaO 0.01 0.05 0.01 0.03 0.12 CaO 13.48 10.82 13.11 13.47 12.52 13.06 13.23 13.22 14.10 12.75 ::I :::!". Na20 11.69 11.78 11.78 11.74 10.81 Na1 0 3.90 4.81 3.87 3.71 4.21 3.92 3.77 3.83 3.65 3.98 ::I K,O 0.05 0.10 0.05 0.06 0.32 K,O 0.19 0.27 0.20 0.17 0.23 0.22 0.19 0.22 0.18 0.23 c ro Cr20 3 0.00 0.00 0.00 0.00 0.00 Cr10 3 0.01 0.00 0.00 0.00 0.02 0.03 0.02 0.01 0.00 0.01 a. Total 100.65 100.62 100.25 100.07 99.81 Total 100.01 99.29 99.05 98.86 98.74 98.21 98.08 97.94 97.78 97.31

s, 3.03 3.02 3.03 3.02 2.93 s, 2.39 2.49 2.40 2.37 2.43 2.40 2.38 2.39 2.35 2 41 Tl 0.00 0.00 0.00 0.00 0.00 r, 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 AI 0.97 0.97 0.97 0.97 0.98 AI 1.55 1.44 1.54 1.57 1.51 1.52 1.56 1.55 1.56 1.53

Fetot 0.00 0.00 0.00 0.01 0.08 Fe tot 0.03 0.06 0.03 0.03 0.03 0.03 0.03 0.03 0.03 003 Mn 0.00 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mg 0.00 0.00 0.00 0.00 0.06 Mg 0.01 0.03 0.02 0.01 0.01 0.02 0.01 0.01 0.02 0.01 Ca 0.00 0.00 0.00 0.00 O.ot Ca 0.66 0.53 0.65 0.67 0.62 0.65 0.66 0.66 0.70 0.64 Na 0.99 0.99 1.00 0.99 0.92 Na 0.34 0.43 0.35 0.33 0.38 0.35 0.34 0.35 0.33 0.36 K 0.00 0.01 0.00 0.00 0.02 0.01 0.02 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

Or 0.28 0.55 0.28 0.33 1.90 Or 1.09 1.62 1.17 099 1.34 1.28 1.12 1.28 1.02 1.35 Ab 99.67 99.21 99.67 99.52 97.50 Ab 33.99 43.86 34.41 32.93 37.32 34.75 33.64 33.95 31.57 35.61 An 0.05 0.23 0.05 0.14 0.60 An 64.92 54.52 64.42 66.07 61.34 63.97 65.24 64.76 67.40 63.04

Mineral: Pyroxene (0=6) Mineral: Pyroxene (0=6) Comment A A. A. A A. A. A. A. A. Comment A. A. A. A. A. A A.

Si02 48.99 45.22 41.43 37.97 39.56 39.47 43.25 41.71 45.33 45.64 Si02 31.46 30.72 31.46 31.42 5.53 4.67 0.18 0.04 0.06 0.14

Ti0 2 0.00 0.05 7.57 0.31 0.08 0.08 10.26 0.04 4.10 0.14 Ti01 0.09 0.12 0.07 0.05 0.04 0.05 0.02 0.00 0.01 000

AI20 3 16.85 16.57 15.55 16.34 16.53 16.85 14.49 16.66 15.69 16.71 Alp 3 13.07 12.89 12.86 12.76 1.16 1.21 0.03 0.02 0.02 0.06

Fe0101 9.79 12.88 10.82 18.65 17.17 16.78 6.60 14.74 8.65 10.25 Fe0 1.,1 29.61 30.03 29.52 28.53 35.71 31.59 37.23 33.38 33.22 27.07 MnO 0.03 0.03 0.00 0.04 0.02 0.03 0.02 0.05 0.02 0.02 MnO 0.03 0.03 0.03 0.06 0.50 0.36 0.42 0.91 0.50 0.83 MgO 4.27 5.77 4.86 8.33 7.66 7.55 3.19 6.28 4.04 5.02 MgO 12.15 12.52 12.23 12.33 10.37 14.62 9.40 11.65 14.50 14.33 CaO 0.52 0.51 0.60 0.45 0.45 0.47 0.72 0.45 0.56 0.49 Cao 0.41 0.32 0.32 0.32 8.48 8.37 10.54 11.32 8.69 13.38

Na20 4.24 3.21 3.90 1.92 2.70 2.62 4.97 3.59 5.06 4.56 Na 20 0.13 0.11 0.10 0.11 0.12 0.05 0.03 0.04 0.03 0.02 K,O 3.15 2.88 2.04 1.66 1.42 1.62 1.55 1.48 152 1.70 K,O 0.13 0.08 0.10 0.12 0.19 0.09 0.01 0.00 0.00 0.01

Cr20 3 0.04 0.08 0.03 0.06 0.06 0.04 0.02 0.03 0.03 0.03 Cr 20 3 0.02 0.03 0.01 0.05 0.00 0.02 0.02 0.05 0.04 0.03 Total 87.88 87.20 86.80 85.73 85.65 85.51 85.07 85.03 85.00 84.56 Total 87.10 86.85 86.70 85.75 62.10 61.03 57.88 57.41 57.07 55.87

s, 2.04 1.91 1.79 1.65 1.71 1.71 1.91 1.80 1.96 1.96 Si 1.39 1.36 1.39 1.40 0.36 0.29 0.01 0.00 0.00 0.01 r; 0.00 0.00 0.25 0.01 0.00 0.00 0.34 0.00 0.13 0.00 Tl 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 AI 0.83 0.82 0.79 0.84 0.84 0.86 0.75 0.85 0.80 0.85 AI 0.68 0.67 0.67 0.67 0.09 0.09 0.00 0.00 0.00 0.00

Fetot 0.34 0.45 0.39 0.68 0.62 0.61 0.24 0.53 0.31 0.37 Fe tot 1.09 1.11 1.09 1.07 1.92 1.65 2.18 1.91 1.87 1.53 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 O.Q3 O.Q2 0.02 o.os 0.03 0.05 Mg 0.26 0.36 0.31 0.54 0.49 0.49 0.21 0.41 0.26 0.32 Mg 0.80 0.83 0.81 0.82 0.99 1.37 0.98 1.19 1.46 1.44 ca 0.02 0.02 0.03 0.02 002 0.02 0.03 0.02 0.03 0.02 ca 0.02 0.02 0.02 0.02 0.58 0.56 0.79 0.83 0.63 0.97 Na 0.34 0.26 0.33 0.16 0.23 0.22 0.42 0.30 0.42 0.38 Na 0.01 0.01 0.01 0.01 0.01 0.01 0.00 0.01 0.00 0.00 K 0.17 0.16 0.11 0.09 0.08 0.09 0.09 0.08 0.08 0.09 K 0.01 0.00 0.01 0.01 0.02 0.01 0.00 0.00 0.00 0.00

Wo 2.36 2.07 2.59 1.50 1.53 1.63 3.67 1.65 2.50 2.05 Wo 1.04 0.80 0.81 0.82 19.32 17.85 24.26 24.77 18.64 27.80 En 26.95 32.61 29.19 38.64 36.29 36.47 22.61 32.00 25.13 29.17 En 42.68 43.34 43.05 43.99 32.87 43.38 30.11 35.47 43.28 41.43 ,, 35.89 41.72 37.75 48.28 45.55 45.45 27.92 42.56 31.45 34.33 ,, 55.69 55.37 55.68 54.68 47.31 38.58 45.50 39.60 37.97 30.70 N 0'1 ...... Appendix E - Geochemical analyses of the Standard Core and Brecciated Core sequences.

Note:

1. Dolerite Samples 1 to 7 of the Standard Core are subdivided using the same naming

scheme as applied to those dolerites in Appendix C:

• Dolerite 1 is of dolerite Type 1 (STD-DOL 1).

• Dolerites 2 to 4 are of dolerite Type 2 (STD-DOL 2).

• Dolerites 5 to 7 are of dolerite Type 3 (STD-DOL 3).

262 Table E.l- Geochemical analyses of the Standard Core.

Type Dolerite Dolerite Dolerite Dolerite Dolerite Dolerite Dolerite Sandstone Sandstone Sandstone Sample No. 1 2 3 4 5 6 7 1 2 3

Si02 51.13 51.99 51.72 51.43 52.03 52.4 50.2 81.26 83.8 77.5 Al,o, 14.37 13.65 14.23 14.13 13.1 13.06 15.06 8.11 8.17 11.75

Fe 20 3 10.63 12.26 11.69 11.78 12.86 13.15 12.31 1.3 0.98 1.69 MgO 8.53 6.05 5.78 5.83 5.39 5.77 3.27 0.53 0.24 0.31 CaO 10.04 9.99 10.29 10.07 8.74 8.53 6.24 0.72 0.77 0.22

Na20 2.14 2.43 2.41 2.72 2.75 2.73 3.34 1.34 1.14 1.99

K20 0.73 0.86 0.83 0.83 0.92 0.87 1.02 4.95 3.15 3.76

Ti02 0.91 1.17 1.15 1.14 1.52 1.55 1.77 0.08 0.21 0.49

P20 5 0.14 0.21 0.2 0.2 0.21 0.23 0.27 0.02 0.11 0.07 MnO 0.16 0.19 0.19 0.18 0.19 0.19 0.1 0.01 0.02 0.02 cr,o, 0.076 0.035 0.035 0.036 0.021 0.021 0.023 0.002 0.003 0.004 Ni 160 47 48 46 48 61 64 <20 <20 <20 Sc 34 40 40 39 33 32 36 1 4 5 LOI 0.9 0.9 1.2 1.4 2 1.2 6.1 1.6 1.3 2 Sum 99.74 99.74 99.76 99.76 99.73 99.73 99.72 99.87 99.89 99.84

Ba 211 285 258 292 434 352 467 1048 832 988 Be <1 <1 <1 <1 <1 <1 1 <1 1 1 Co 45.7 42.9 38.9 41.3 41.4 46.1 48 2 3 1.5 Cs 0.6 0.4 0.5 0.3 0.3 0.3 0.6 1.1 1.4 1.5 Ga 17.6 18.7 17.1 19 18.9 20.2 22.1 10.6 8.6 13 Hf 2.5 3 3 2.7 3.4 4.3 4.7 3.1 3.2 7.6 Nb 3.4 7.2 6.5 6.4 5.1 5.9 6.7 1.7 4.8 9.4 Rb 19.4 21.1 19.4 18.8 21.3 21 23.9 131.3 103.8 117.9 Sn 1 1 <1 4 1 1 1 <1 2 2 Sr 184.3 225.7 244.2 268.5 296.9 279.2 413.9 134.6 153.4 147.1 Ta 0.2 0.5 0.4 0.4 0.3 0.3 0.4 0.2 0.4 0.8 Th 2 2.3 1.9 2.1 1.7 1.7 1.8 4.5 6.5 9 u 0.3 0.5 0.5 0.5 0.4 0.5 0.5 1.1 1.4 2.5 v 265 312 291 300 332 331 365 16 21 31 w <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 0.9 Zr 92.7 109.9 103.4 101.6 124.3 144.8 163.4 97.3 112.2 259.7 y 24.6 27 24.8 25.1 27.8 31.6 29.3 3.9 12.6 16.7 La 9.5 13.7 12.9 12.6 12 13.7 14.3 7.5 14.8 22 Ce 21.6 29.7 27.9 27.8 27.2 31.3 33.5 13.5 29.8 47.6 Pr 2.72 3.72 3.52 3.58 3.67 4.25 4.54 1.6 3.71 5.67 Nd 12.1 16 15.2 15.4 16.7 19.7 20.1 5.8 13.9 21.9 Sm 3.12 3.85 3.69 3.67 4.27 4.98 4.95 1.05 2.64 4.13 Eu 0.93 1.18 1.13 1.17 1.47 1.55 1.59 0.46 0.69 1.1 Gd 3.75 4.34 4.06 4.09 5.03 5.55 5.69 0.82 2.31 3.44 Tb 0.68 0.76 0.73 0.74 0.88 0.97 0.97 0.13 0.39 0.56 Dy 4.05 4.54 4.36 4.33 4.92 5.35 5.49 0.73 2.26 2.86 Ho 0.87 0.94 0.88 0.88 1.01 1.13 1.08 0.14 0.46 0.6 Er 2.5 2.65 2.53 2.67 2.83 3.12 3.05 0.46 1.26 1.75 Tm 0.37 0.41 0.39 0.4 0.41 0.46 0.45 0.07 0.18 0.29 Yb 2.43 2.68 2.43 2.55 2.56 2.78 2.87 0.48 1.21 2.06 Lu 0.35 0.39 0.37 0.37 0.37 0.41 0.41 0.07 0.17 0.3 Mo 0.3 0.5 0.5 0.5 0.6 0.6 0.5 0.2 0.2 <0.1 Cu 89.3 105.6 105.1 104.5 134.2 123.2 134.2 2.1 3.7 1.6 Pb 1.5 2.1 2 1.7 1.5 1.7 2.1 11.1 2.5 6.6 Zn 30 46 51 36 59 57 115 10 16 26 Ni 63.7 9.8 13.9 15.7 12.9 24.1 53.3 3.1 4 3 As <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 0.7 1.5 <0.5 Cd <0.1 <0.1 0.1 <0.1 <0.1 <0.1 0.2 <0.1 <0.1 <0.1 Sb <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Bi <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Ag <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Au 4.7 3.2 2.5 1.8 1.6 1.2 2.5 <0.5 <0.5 <0.5 Hg 0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 Tl <0.1 <0.1 <0.1 <0.1 <0.1 0.2 <0.1 <0.1 <0.1 <0.1 Se <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

263 Table E.2- Geochemical analyses of the brecciated core sequence A (Core A).

Type Dolerite Dolerite Dolerite Dolerite Dolerite Dolerite Dolerite Dolerite Dolerite Dolerite Breccia Breccia Breccia Breccia Breccia 5ampleNo. 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5

Si02 51.38 51.16 51.05 48.08 48.14 50.78 36.04 36.1 35.83 35.89 62.01 68.89 76.58 74.65 72.21

Al 20 3 14.45 14.5 14.68 17.59 17.59 16.53 16.46 16.57 20.89 21 10.62 9.53 7.34 9.32 10.34

Fe 20 3 12.17 12.28 12.05 9.03 8.94 7.85 10.68 10.56 13.07 13.01 6.82 3.77 1.76 3.21 4.06 MgO 5.87 5.83 5.89 5.59 5.49 5.1 2.79 2.75 3.33 3.34 3.09 1.02 0.49 0.84 1.17 CaO 10.19 10.26 10.37 7.77 7.74 8.33 12.43 12.49 2.58 2.56 5.06 4.98 4.47 2.32 2.08

Na 20 2.39 2.38 2.49 3 3 2.72 2.6 2.61 2.08 2.08 1.18 1.09 0.95 0.68 0.87 K,o 0.71 0.7 0.5 0.48 0.47 0.74 0.48 0.48 0.9 0.91 2.04 3.21 3.09 2.87 2.82

Ti0 2 1.19 1.19 1.18 1.36 1.36 1.06 1.35 1.37 2.09 2.07 0.54 0.38 0.27 0.39 0.5 P20s 0.19 0.18 0.19 0.22 0.22 0.13 0.21 0.21 0.59 0.58 0.2 0.06 O.D3 0.16 0.07 MnO 0.19 0.19 0.19 0.09 0.08 0.1 0.29 0.29 0.26 0.27 0.19 0.06 0.05 0.04 0.04

Cr 20 3 0.023 0.023 0.022 0.028 0.027 0.081 0.026 0.025 0.035 0.036 0.013 0.004 0.003 0.006 0.008 Ni 60 54 65 73 71 140 77 84 87 86 27 <20 <20 <20 22 Sc 41 41 40 47 46 37 46 45 45 45 12 9 5 9 13 LOI 1 1.1 1.1 6.5 6.7 6.3 16.4 16.3 18.1 18 8.1 6.8 4.8 5.4 5.6 Sum 99.75 99.76 99.73 99.69 99.72 99.74 99.73 99.74 99.73 99.73 99.82 99.84 99.87 99.86 99.84

Ba 232 236 500 349 334 318 414 404 358 364 526 760 711 685 686 Be <1 <1 <1 <1 <1 <1 1 <1 1 1 2 2 <1 1 1 Co 42 41.9 43.1 49.2 49.6 51.6 52.4 54.5 71.7 71 12.2 6.3 4.2 9.7 12.3 Cs 0.5 0.5 3.3 0.7 0.7 0.8 0.7 0.7 1.6 1.7 4.6 2.5 1.9 2.4 2.7 Ga 17.9 17.9 19 20.4 21.8 17.8 19.9 19.8 13.5 13.7 14.3 13.8 9.2 12.3 14.2 Hf 2.9 3 3 3.2 3.4 2.8 3.5 3.3 3.9 3.9 5.2 4.8 4 4.2 6.2 Nb 5.5 5.7 6 6.6 6.6 3.7 6.4 6.4 10.9 10.9 8.3 7.4 5.9 6.7 7.8 Rb 15.8 16.2 12 5.8 5.7 19 11.3 11 45.2 45.4 91.3 116.5 106 103.4 106.2 Sn 1 <1 <1 <1 <1 <1 <1 <1 1 1 2 1 <1 1 2 Sr 203.4 203.5 266.4 400.8 401 467.8 482.1 486.5 181.8 183.3 231.7 314.3 311 185.1 207.3 Ta 0.4 0.3 0.3 0.4 0.4 0.3 0.4 0.4 0.6 o.s 0.7 0.6 o.s 0.6 0.6 Th 1.8 1.9 1.9 2.1 1.8 2.5 2 2.1 3.2 3.3 9.5 7.9 8.3 10.7 11.2 u 0.4 0.4 0.4 0.5 0.4 0.3 0.4 0.4 1.3 1.4 2.5 1.9 1.7 2.2 2.2 v 308 304 310 344 335 270 341 341 367 372 76 40 21 49 71 w <0.5 <0.5 <0.5 <0.5 <0.5

264 Table E.3- Geochemical analyses of the brecciated core sequence B (Core B).

Type Dolerite Dolerite Dolerite Dolerite Dolerite Dolerite Dolerite Dolerite Dolerite Dolerite Breccia Breccia Breccia Breccia Breccia Sample No. 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5

Si0 2 51.76 51.6 51.19 41.75 38.26 38.03 45.86 41.71 41.99 41.21 81.72 72.88 72.72 56.68 74.87

Al 20 3 14.69 14.89 14.42 18.45 15.93 15.81 17.18 17.65 17.66 13.31 4.79 12.34 11.5 13.26 10.42

Fe 20 3 10.38 10.36 12.42 9.88 10.53 10.6 14.78 14.84 14.77 11.27 0.92 2.76 3.09 8.61 3.88 MgO 7.83 7.8 5.93 2.6 2.03 2.04 6.41 6.95 6.89 4.7 0.33 1.12 1.43 3.54 1.5 CaO 9.83 9.89 10.41 11.43 13.28 13.34 1.7 5.4 5.35 12.37 4.82 0.97 2.04 4.68 1.73 Na20 2.34 2.37 2.41 2.89 2.81 2.79 5.09 3.27 3.26 2.32 0.39 0.92 2.03 3.32 1.29

K20 0.62 0.62 0.71 0.87 0.97 0.97 0.58 0.63 0.63 0.46 1.66 2.77 3.24 1.73 2.65 Ti02 0.95 0.94 1.18 1.46 1.3 1.3 1.39 1.37 1.37 1 0.35 0.55 0.38 0.84 0.49 P20s 0.12 0.12 0.18 0.24 0.21 0.21 0.23 0.22 0.22 0.16 0.02 0.1 0.04 0.09 0.04 MnO 0.16 0.16 0.19 0.19 0.29 0.29 0.05 0.08 0.08 0.26 0.11 0.03 0.05 0.1 0.04

Cr20 3 0.06 0.061 0.019 O.D28 O.D25 0.025 0.028 0.027 0.026 0.02 0.004 0.01 0.006 0.013 0.005 Ni 91 90 59 67 65 61 73 71 68 65 <20 <20 27 43 <20 Sc 33 34 41 49 44 45 45 46 46 36 3 9 6 24 7 LOI 1 0.9 0.7 9.9 14.1 14.3 6.4 7.5 7.4 12.7 4.8 5.4 3.3 6.9 2.9 Sum 99.76 99.75 99.76 99.73 99.76 99.74 99.73 99.69 99.71 99.75 99.92 99.83 99.82 99.78 99.84

Ba 210 207 206 476 341 335 317 342 338 220 333 643 858 557 727 Be <1 <1 <1 1 1 <1 1 <1 <1 <1 <1 3 2 1 2 Co 44.3 42.3 43.7 45.2 44.6 44.6 63.6 54.1 50.5 42.2 2.9 7.5 5.9 18.6 6.7 Cs 0.8 0.8 0.5 0.7 1 1 1.8 1.7 1.7 0.7 1.6 6.9 3.7 1.7 5 Ga 16.5 17.3 17.8 22.4 19.1 17.7 15.4 19.9 19.9 16.1 6.9 15 12.4 18.3 12.2 Hf 2.4 2.5 2.9 3.8 3.2 2.9 3.4 3.1 2.9 2.3 8.9 6.3 3.9 5.7 6.7 Nb 3.3 3.2 5.3 7.3 6.3 6.3 6.7 6.2 6.1 4.7 8.8 13 9.3 8.7 9.5 Rb 16.3 16.3 17.7 18.9 24.5 23.5 11.8 10.1 9.9 10.1 57.9 108.4 113.1 55.1 97.7 Sn <1 <1 1 1 1 <1 <1 <1 1 <1 1 3 2 2 4 5r 186.1 172.4 209.5 390.1 493 486.5 196.8 309.9 304.8 580.2 219.8 159.8 201.9 294.5 187.1 Ta 0.3 0.3 0.4 0.4 0.4 0.5 0.4 0.4 0.4 0.3 0.7 0.8 0.6 0.5 o.s Th 2.3 2.4 1.7 2 1.8 1.9 2 1.8 1.9 1.5 5.3 14.1 6 6.6 11.1 u 0.3 0.3 0.4 0.5 0.5 0.4 0.6 0.5 0.4 0.3 1.8 4.2 1.5 2.1 2.3 v 254 242 316 377 336 325 350 341 333 256 19 71 47 163 43 w <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 0.8 1.4 0.9 0.8 0.9 Zr 88.6 86.2 102.2 128.2 116 114.5 114.7 116.5 115.3 84.1 329.5 213.6 150.5 195.9 234.2 y 23.1 22.1 26.6 38.3 34.8 34.2 28.8 29.1 28.4 23.5 16.6 24.7 12.5 20.4 15.8 La 9.4 9.1 10.5 16.3 13.6 13.8 11.5 11.3 10.8 8.4 8.6 37.1 14.6 16.9 27.3 Ce 21.7 21.1 23.9 33.3 30 30.4 27.6 25.8 25.8 18.9 16.9 67.4 26.8 37.7 56.2 Pr 2.84 2.69 3.12 4.67 3.88 3.81 4.08 3.46 3.37 2.5 2.03 8.43 3.48 4.48 6.57 Nd 12.1 11.5 14 21.2 17.6 17.9 18.9 15.8 15 11.7 8.1 29.5 14.2 18 24.9 Sm 3.11 2.91 3.55 5.16 4.3 4.26 5.01 4.12 4.06 3 1.68 5.25 2.23 3.62 4.45 Eu 0.94 0.91 1.12 1.68 1.46 1.48 1.49 1.41 1.41 0.97 0.49 1.22 0.73 0.84 0.87 Gd 3.62 3.47 4.16 6.02 5.35 5.28 5.68 4.9 4.79 3.59 1.78 5.49 2.36 3.59 3.6 Tb 0.66 0.63 0.77 1.07 0.98 0.97 0.97 0.85 0.83 0.68 0.37 0.82 0.35 0.65 0.58 Dy 3.86 3.76 4.55 6.28 5.75 5.93 5.43 4.93 4.86 4.03 2.49 4.79 2.05 3.54 2.97 Ho 0.83 0.79 0.98 1.33 1.21 1.19 1.11 1.04 1.04 0.9 0.55 0.86 0.41 0.76 0.58 Er 2.42 2.3 2.83 3.9 3.37 3.41 3.07 3.11 3.08 2.64 1.88 2.53 1.15 2.15 1.61 Tm 0.37 0.33 0.42 0.58 0.5 0.5 0.45 0.47 0.45 0.4 0.3 0.41 0.18 0.35 0.26 Yb 2.28 2.11 2.58 3.6 3.08 2.99 2.88 2.92 2.93 2.55 2.03 2.57 1.21 2.14 1.52 Lu 0.34 0.32 0.39 0.52 0.46 0.45 0.44 0.45 0.43 0.39 0.32 0.42 0.19 0.37 0.27 Mo 0.3 0.3 0.5 0.6 0.6 0.5 1.1 0.4 0.4 0.5 0.4 1.7 0.3 5.6 0.4 Cu 89.3 89.1 134.8 158.7 140.9 140.2 145.3 148.6 147.9 95.4 3.2 2.8 3.2 41.3 6.2 Pb 1.6 1.7 1.8 3.2 3.8 3.6 3.5 2.2 2.3 4.2 1.5 4.3 3.9 10.1 3.6 Zn 34 35 42 107 100 100 108 100 100 71 7 18 18 72 35 Ni 36.4 35.1 22.9 68 64.7 64.8 76 68.3 67.3 63 4.7 21.7 10.9 36.6 12.7 As <0.5 0.6 0.8 0.6 0.7 0.7 0.9 0.6 0.6 1.6 <0.5 1.1 <0.5 0.5 <0.5 Cd <0.1 <0.1 <0.1 0.1 0.1 <0.1 <0.1 <0.1 0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Sb <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Bi <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Ag <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Au <0.5 <0.5 0.6 2.1 0.6 1.4 1 1.6 1.1 1 <0.5 1.4 0.8 1.2 0.7 Hg <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 0.01 0.01 <0.01 0.03 Tl <0.1 <0.1 <0.1 0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 0.2 <0.1 0.2 Se <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <::0.5 <0.5 <0.5 <0.5

265