Composition and structure of titanian andradite from magmatic
and hydrothermal environments
by
Elizabeth Hilton
B.Sc. (Hons), Saint Mary's University, 1998.
A. THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS
FOR THE DEGREE OF
MASTER OF SCIENCE
in
THE FACULTY OF GRADUATE STUDIES (Geological Sciences Division, Department of Earth and Ocean Sciences)
We accept this thesis as conforming to the required standard
THE UNIVERSITY OF BRITISH COLUMBIA May, 2000. O Elizabeth Hilton, 2000. In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission.
Department of (fariV* Oceav\ Sciences,
The University of British Columbia Vancouver, Canada
Date Kft^ JOOO. Abstract
Titanian andradite provides a wealth of information about the environments in which they form. Zippa Mountain pluton and the Crowsnest volcanic rocks provide examples of titanian andradite formed indifferent environments (e.g., magmatic, skarn, volcanic, and hydrothermal). Electron-microprobe, petrographic, and geochemical analysis, coupled with X-ray techniques were used to determine the composition, structure, site occupancies, and to discriminate between titanian andradite formed in different environments. Site occupancies, determined from the study samples, are as follows: Ca2+ and Na+ are always assigned to the X site; Mn2+ is preferentially assigned to the X site, but may also be at the Y site; Al3+, Mg2+, Cr3+, V3+, Ti4 +, and Fe2f are always assigned to the Y site; Fe3+ may be assigned into the Y site or the Z site; and Si4+, Zr4^, and H4+ are always assigned to the Z site. The titanium substitution mechanism may be
3+ via the TiMgFe2. exchange component, indicative of octahedral Ti substitution and octahedrally controlled cell volume. Chemical zoning of magmatic and skarn titanian
andradite is irregular. Garnet from volcanic samples have irregularly zoned cores and
regularly zoned rims as does the magmatic cumulus sample. Hydrothermal samples
show regular chemical zonation.
EPMA data reveals titanian andradite zoning patterns within different rock types
and different formation environments. Dark zones in the volcanic garnet contain more
Ti02 and A1203 and less Fe203 than lighter zones. Melasyenite samples show positive
correlation between Ti02 and Fe203. Conversely, pyroxenite samples show regular
zoning with darker zones having more A1203 and less Fe203 than lighter areas. In these Ill
samples, Ti02 and Fe203 are negatively correlated. In terms of Thompson components, magmatic samples have small norms, negative MgCa-, very small H4Si- component, and positive FeMg-, whereas hydrothermal samples have positive H4Si- components, zero to slightly positive FeMg-, and large norms. On average, skarn samples have equal amounts
3+ of both TiSi- and TiMgFe2_ components and are therefore intermediate between magmatic and hydrothermal samples. Oxygen fugacify and activity of silica are
3f correlated by TiMgFe2. and TiSi- components and indicate that the magmatic samples
formed under low fQ2 conditions, skarn samples inherited \hefQ2 signature by interaction with early magmatic fluids, whereas the hydrothermal sample crystallised from a more
evolved fluid which had a higher^ and asi02. Table of Contents
Abstract
List of Figures vi
List of Tables viii
Acknowledgments ix
Chapter 1: Introduction 1
1.1 General Introduction 1
1.2 Purpose 2
Chapter 2: Literature Review of Titanium Andradite 4
2.1 Overview of Titanian Andradite 4
2.2 Anisotropy 5
2.3 Zoning in Titanian Andradite..... 6
Chapter 3: Sample Suite and Petrography 10
3.1 Geological Setting and Sample Suite 10
3.1.1 Geological Setting..., 10
3.1.2 Sample Suite 12
3.1.3 Whole Rock Geochemistry and Geochemical Methodsl2
3.2 Petrography.... 14
3.2.1 Sample Description 14
3.2.2 Petrography 16
3.2.3 Scanning Electron Microscopy 20
Chapter 4: Chemical Characteristics and Representation of Ti-Andradite....56
4.1 Chemical Mineralogy 56
4.1.1 Electron Microprobe Analyses 56
4.1.2 Compositional Zoning 56
4.2 Representation of Analyses 64 4.3 Summary : 71
Chapter 5: Other Chemical Techniques Used to Describe Ti-Andradite 101
5.1 Introduction 101
5.2 Wet-chemistry 101
5.3 FTIR and Estimates of OH 101
5.3.1 Literature Review of OH Site Occupancy 101
5.3.2 FTIR Methods : 103
Chapter 6: X-ray Diffraction Analysis 106
6.1 Introduction to Diffractometry 106
6.2 The Andradite Unit Cell by Powder Diffraction 107
6.3 Single Crystal Diffractometry 109
6.4 Summary 111
Chapter 7: An Analysis of Site Occupancy in Ti-Andradite 116
7.1 Recapitulation of Andradite Crystals 116
7.2 Literature Review of Site Occupancy in Ti-Andradite. 116
7.3 Results and Ideas from This Study 118
Chapter 8: General Conclusions and Petrogenesis 126
References 130
Appendix A EPMA Error Analysis 137
Appendix B Cation Normalisation Routine: Algorithm and Matlab Code... 163
Appendix C CD Rom of Complete EPMA Tables back cover pocket vi
List of Figures
Figure 1 Zippa location map (BC) 3
Figure 2 Zippa sample location map 24
Figure 3 Cliff sample location map 25
Figure 4 Glacier sample location map 26
Figure 5 Bartnick sample location map 27
Figure 6 Geochemical data plotted as alkali-silica, AFM diagrams 30
Figure 6 (cont'd) Trace element variation diagrams 31
Figure 7 Polished thin section pictures 32
Figure 8A SEM images of zoning of Zippa magmatic samples 43
Figure 8B SEM images of zoning of cumulus and Crowsnest samples 46
Figure 8C SEM images of zoning of dyke samples 49
Figure 8D SEM images of zoning of skarn samples 51
Figure 9 X-ray maps for ZM39B-B 55
Figures 10-24 Line traverses plotted 76
Figure 25 SEM images showing line traverses on grains 91
Figure 26 TCS component plots 96
Figure 27 TCS compilation plots 99
Figure 28 TCS compilation plots for norm of the vector 100
Figure 29 Comparison of duplicate FeO analyses 105
Figure 30 Z95-1 2 theta correction factors 113
Figure 31 Measured cell volume plots 115 Vll
Figure 32 Portion of the garnet structure projected down the c-axis 122
Figure Al EPMA analyses for the non-calibration standard plotted over time.. 140
Figure A2 Grid of analyses on the non-calibration standard 141
Figure A3 Analytical uncertainty plotted against the IS variation for EPMA analyses
for the non-calibration standard 142
Figure A4 EPMA analyses of Andr point 1 from the non-calibration standard, over
time 143
Figure A5 EPMA analyses of Andr point 2 from the non-calibration standard, over
time 144
Figure A6 EPMA analyses of Andr point 3 from the non-calibration standard, over
time 145
Figure A7 EPMA analyses of Andr point 4 from the non-calibration standard, over
time 146
Figure A8 EPMA analyses of Andr point 5 from the non-calibration standard, over
time 147 Vlll
List of Tables
Table 1 Sample suite from Zippa Mountain and related assemblages .23
Table 2 Geochemical data with norms 28
Table 3 Petrography : 37
Table 4 Representative microprobe analyses 72
Table 5 Zoning patterns summary 94
Table 6 Wet-chemical analyses of FeO in select garnet samples 104
Table 7 Calculated unit cells for selected andradite crystals from this study. 114
Table 8 J Widely accepted cation site occupancies 123
Table 9 Cation site assignments and totals '. 124
Table A1 EPMA analyses for calibration standards over time 148
Table A2 Calculated wt% for the andradite non-calibration standard 153
Table A3 EPMA analyses for the andradite non-calibration standard over
time •. 154
Table A4 EPMA analyses for the andradite non-calibration standard grid 155
Table A5 EPMA analyses for the andradite non-calibration standard, organised by
point, over time 156
Table A6 Calculated mean and standard deviation for the andradite non-calibration
standard 162 IX
Acknowledgments
The author wishes to thank Dr. Kelly Russell, Dr. Greg Dipple, and Dr. Lee Groat for guidance, supervision, and improvements of this work. Special thanks to Dr. Mati
Raudsepp for guidance and helpful suggestions for instrumentation. Dr. Ian Coulson is thanked for reviewing the thesis and for many helpful suggestions. Most of all I wish to thank my husband, my sisters, and parents for their support and encouragement. 1
Introduction
1.1 Introduction
Titanian andradite forms in both magmatic and hydrothermal environments and is most commonly associated with silica-undersaturated rocks (Howie and Woolley 1968).
Titanian andradite forms an important link between magmatic and hydrothermal
environments. Variations in its composition can be used to track variables such as fQ2
and aSi02, making it an essential phase for studying the chemical dynamics of magmatic and hydrothermal systems and also for establishing records of fluid evolution between the two systems (Russell et al. 1999). Occurrences of purely magmatic titanian andradite from western Canada include the Crowsnest volcanics, Alberta (Dingwell and Brearley
1985) and the Zippa Mountain pluton, British Columbia (e.g. Lueck and Russell 1994)
(Figure 1). Andradite from both these localities is examined in this thesis.
The Crowsnest volcanics contain examples of titanian andradite formed in extrusive alkaline igneous rocks (Dingwell and Brearley 1985). The garnet occurs as phenocrysts along with aegirine-augite, sanidine, analcite, and rare plagioclase in trachyte and phonolite flows, agglomerates and tuffs (Dingwell and Brearley 1985). The garnet is chemically zoned with Ti and Fe contents decreasing from core to rim
(Dingwell and Brearley 1985).
The Zippa Mountain pluton is located in the Iskut River map area, in northern
British Columbia about 10 km southwest of the confluence of the Iskut and Craig Rivers.
The Zippa Mountain pluton (hereafter ZMP) is roughly 3.5 by 5 km in size and has an elliptical shape (Lueck and Russell 1994). Chemically, the pluton is strongly silica- 2 undersaturated and alkaline (Coulson et al. 1999). Titanian andradite occurs as a primary magmatic phase in all rock types in the ZMP including syenite, melasyenite, and pyroxenite (Lueck and Russell 1994; Coulson et al. 1999). The pyroxenite contains up to
30% titanian andradite, melasyenite contains 5 to 20%, and syenite contains 5 to 10%
(Lueck and Russell 1994). Trachytic K-feldspar, aligned aegirine-augite crystals, titanian andradite and pyroxene-rich layers define a fabric within the syenite and pyroxenite which is interpreted as cumulus in origin (Coulson et al. 1999). At Zippa Mountain, titanian andradite also occurs in skarn. The skarn is formed by infiltration of magmatic volatiles into Paleozoic calcite marble and contains garnet of both grossular and andraditic compositions (Jaworski and Dipple 1996).
1.2 Purpose
A suite of hand samples and polished thin sections from ZMP, including both magmatic and skarn samples, as well as a volcanic sample from Crowsnest, Alberta were analysed. The purpose of this study was to determine the composition, chemical zonation patterns, and structure of titanian andradite from magmatic and hydrothermal environments. Observations and data were collected by electron probe micro-analysis
(EPMA), whole rock geochemical analysis, infrared spectroscopy, and X-ray diffraction.
Chemical compositions were compared against environment of formation. The effect of
OH in natural titanian andradite on substitution mechanisms was also studied. The role of titanium in the crystal chemistry of natural titanian andradite was determined; specifically the site occupancy and valence(s). 3
Stikine Terrane 1 Butterfly Pluton 2 Zippa Mountain 3 Galore Creek 4 Ten Mile Creek 5 Rugged Mountain
Quesnel Terrane 6 Duckling Creek/ Lorraine Complex 7 Mount Polley 8 Rayfield River 9 Kamloops Syenite 10 White Rocks Mountain 11 Averill Pluton 12 Kruger Mountain
13 Crowsnest Volcanics
Terranes
Wrangellia
] Stikinia
] Quesnellia | Cache Creek
o 400
km
Figure 1. Map of the British Columbia cordillera showing Mesozoic silica-undersaturated alkaline plutons, and the Cretaceous Crowsnest Formation, Alberta (after Lueck and Russell 1994). 4
Literature Review of Titanian Andradite
2.1 Overview of Titanian Andradite
21 A simplified chemical formula for garnet is XiY2(ZO^, where X=Ca., Mg, Fe ",
Mn2+; 7=A1, Fe3', Mn3+, V3"', Ti4', Cr3f; and Z= Si. In titanian andradite, the Z site is silica-undersaturated which allows for substitution, or coupled substitutions, of cations
such as Ti. The structure consists of alternating Z04 tetrahedra and Y06 octahedra which share corners to form the three-dimensional framework (Schwartz et al. 1980). The X cation is coordinated by eight oxygens and forms a third kind of polyhedron, a distorted cube or a triangular dodecahedron.
Grossular and andradite garnets are members of the grandite garnet series. Many andradites have compositions fairly close to the theoretical end-member. Grossular is the next common component because of the complete solid-solution that exists within the grandite series. Andradite forms a solid-solution series with the chemical end- members schorlomite and morimotoite. Schorlomite is a species of garnet containing
more than 15 wt.% Ti02 (Peterson et al. 1995). The X site of schorlomite is almost completely filled with Ca; the Y site contains Ti4+, Fe3+ and Fe2+, and Al; and the Z site is filled by Si and Fe31 and Fe2+ (Peterson et al. 1995). Morimotoite is a titanian garnet
2t which contains more than 50 mol.% of the morimotoite component, Ca3TiFe Si3012, which is derived from end member andradite by the substitution Ti + Fe2+ = 2Fe3+
(Henmietal. 1995).
The mechanism by which Ti substitutes into the andradite structure remains controversial and is examined in detail in Chapter 7. Whereas previous workers 5 indicated a direct Ti - Si substitution (e.g. Manning and Harris 1970; Weber et al. 1975b) more recent work by Armbruster et al. (1998) suggest a complex substitution whereby Al is concentrated on the octahedral site, and Ti4' can be either octahedrally or tetrahedrally coordinated, but with OH-, Fe3+, or Fe2! fdling most of the tetrahedral vacancies. All titanian andradites have an expanded tetrahedron compared to other andradites because of the hydrogarnet substitution or because of tetrahedral iron incorporation (Armbruster etal. 1998).
2.2 Anisotropy
Anisotropy is visible in titanian andradite optically, with the use of conventional optical microscopy. By definition, an optically anisotropic garnet cannot be cubic, however techniques which have higher resolution than the optical microscope, such as
X-ray diffraction, may indeed indicate an overall cubic habit (Allen and Buseck 1988).
Birefringent zones represent intermediate members of the grandite series whereas isotropic zones are closer to end-member compositions (Ivanova et al. 1998). Early workers commonly attributed anisotropy in andradite to strain or twinning (Chase and
Lefever 1960) and lamellae with compositional differences were believed to have been formed after growth (Hirai et al. 1982). More recent workers attribute anisotropy to structural inhomogeneities related to the mechanism of growth (Gali 1983; Akizuki
1984) and most commonly to cation ordering of Fe3+ and Al at the octahedral sites
(Akizuki et al. 1984; Akizuki 1984). Rossman and Aines (1986) were the first to propose that Fe3+-Al ordering was not the cause of birefringence in garnet, but that it was the result of low-symmetry distribution of OH groups. Authors in the late 1980's attributed anisotropy to some combination of strain, cation ordering, and noncubic distribution of 6
OH groups (Allen and Buseck 1988; Kingma and Downs 1989; Hatch and Griffin 1989) and even suggested that low symmetry may be the result of temperature-induced order- disorder phase transformation (Hatch and Griffin 1989). Ivanova et al. (1998) suggest that inhomogeneity results from the coexistence of two types of layers with different
Fe37Al ratios and state that birefringent zones themselves contain very fine zones, usually intermediate in composition within the grandite series.
2.3 Zoning in Titanian Andradite
Zoning is found in many minerals, including titanian andradite. Normal zoning in andradite shows an increase in Fe from core to rim, whereas reverse zoning has a decrease in Fe and an increase in Al from core to rim (Vlasova et al. 1985). Zoning can form as a result of either changing temperature (Vlasova et al. 1985) or external forcings at the site of the crystal growth (Jamtveit 1999) which include variations in oxygen fugacity, pressure, pH, and fluctuations in magmatic water content and storage depth
(Holten et al. 1997). Oscillatory zoning is a primary growth texture which is commonly superposed on longer-scale zoning, either normal or reversed (Shore and Fowler 1996).
Oscillatory zones are narrow with sharp contacts which may indicate either rapid crystal growth or rapid changes in hydrothermal solutions (Lessing and Standish 1973). Two explanations for the formation of oscillatory zoning include; extrinsic mechanisms, such as physical or chemical changes within the bulk system that are independent of local crystallisation, or intrinsic mechanisms which link crystal growth to purely local phenomena (Shore and Fowler 1996). In general, small-scale growth mechanisms are responsible for oscillatory zoning, such as u.m-scale large amplitude variation between compatible and incompatible elements (Shore and Fowler 1996). Adsorption of minor or 7 trace elements has also been proposed as a mechanism for sector zoning (Shore and
Fowler 1996).
Many workers have studied zonation patterns in titanian andradite. Gomes
(1969) found a direct correlation between colour and Ti concentration, which was corroborated by Dingwell and Brearley (1985). However, Lessing and Standish (1973), working with samples where 90% of zones were anisotropic, state that darker zones have higher Al concentrations, which was later refuted by Murad (1976) who found that birefringent zones have higher Al concentrations. Murad (1976) also found that isotropic, andradite-rich zones require a higher temperature of formation than do birefringent zones based on increasing grossular content with falling temperature in granditic garnet.
Samples studied by Gomes (1969) displayed cores that tend to be rich in Ti and poor in Si and Fe relative to the rims. He argued that Ti replaced both Si and Fe, and showed that the unit cell increased in proportion to the Ti content. Cygan and Lasaga
(1982) found that Fe increases and Mg decreases core to rim, Ca and Mn exhibit a slight zoning at the edges of grains, whereas Si, Al, and Ti remain unchanged. Crowsnest samples (Dingwell and Brearley 1985) have very different zoning patterns which show
Mn, Al enrichment and Ti, Fe depletion in the core, at the boundary of the core Mn and
Al decrease with an increase in Ti and Fe, whereas the rim exhibits oscillatory zoning superimposed on normal zoning with Mn and Al increasing and Ti and Fe decreasing toward the edge. However, Hickmott and Shimizu (1990) suggest that Ti may be less soluble in an intergranular fluid which may lead to slow transport and therefore enrichment near crystal rims during rapid garnet growth. Commonly, the distribution of 8
Mn displays a bell-shaped profile in garnet (Hiekmott and Shimizu 1990; Nakano and
Ishikawa 1997).
Kerr (1981) describes two different zoning patterns in garnet. The first has an
Mg-rich core with Fe, Mn, and Ca increasing at the margin; whereas the second pattern has a Ca-rich core with other elements antipathetic. Smith and Boyd (1992) state that the most common pattern of zonation shows Cr decreasing from core to rim which could form by either growth of Cr-poor garnet during cooling at constant pressure, or by diffusion during a pressure decrease. Badar and Akizuki (1997) describe two types of chemical zoning occurring during crystal growth: the first is nearly homogeneous in chemical composition and lacks fine growth lamellae; and the second consists of fine growth lamellae with various chemical compositions.
Ivanova et al. (1998) describe garnet with isotropic zones of 3 to 4 urn thick that alternate with birefringent zones 10 to 15 u.m thick. These authors state that fine growth zonality originates from non-stationary growth dynamics, and that compositional zoning is the result of abrupt or continuous changes in the composition of the solution, as well as in P-T conditions.
Zoned titanian andradite also forms in the skarn environment. Concentric zoning is common in both magmatic and hydrofhermally grown crystals (Jamtveit 1999).
Vlasova et al. (1985) describe three types of zoning in skarn garnet: the first is defined by
Fe203 contents and is characteristic of true calcareous skarns; the second is characterised by a grossular-rich component which contains significant pyralspite components and varying contents of Ca, Mn, and Fe; and the third type contains pyrope components ranging from 4 to 25 mol% which show reverse zoning. 9
Jamtveit et al. (1993; 1995) state that zoning results from changes in the hydrothermal fluid composition at the site of garnet growth. These authors describe epitaxial growth of andradite on preexisting garnet of higher grossular compositions; a rim ward decrease in Mn, Ti, Zr, and Al; and state that the growth rate of andradite rims was larger than the cores. Jamtveit and Hervig (1994) report garnet rims enriched in light REE's, As, W, Mo, Fe, but depleted in Zr, Y, Ti, and Al, and state that isotope signatures are controlled externally during all stages of crystallisation.
Jamtveit (1999) and Jamtveit et al. (1995) state that Al-Fe partitioning between garnet and solution is sensitive to variations in temperature, pH, oxygen fugacity, and CT activity. Zonation may be the result of variable concentration gradients in the pore-fluid near the garnet fluid interface, and variations between layers are controlled by growth rather than by dissolution processes (Jamtveit 1999). 10
Sample Suite and Petrography
3.1 Geological Setting and Sample Suite
3.1.1 Geological Setting
The Zippa Mountain Igneous Complex (ZMIC) is part of an alkalic magmatic arc plutonic association, characterised by silica-undersaturated intrusions sometimes associated with silica-saturated intrusions (Lang et al. 1995). Both types of intrusions were derived from similar sources and formed in similar tectonic settings (Lang et al.
1995). These complexes were emplaced in the Canadian Cordillera of British Columbia between 210 and 200 Ma based on U-Pb dating of zircon (Lang et al. 1995) and include the Averill (Keep and Russell 1992) and Rugged Mountain (Neill and Russell 1993) plutons. An age of approximately 210 Ma is recorded by U-Pb zircon dating for the ZMP
(Jaworski and Dipple 1996). The silica-undersaturated complexes are characterised by associated pyroxenite and syenite, are generally compositionally zoned, and contain aegirine-augite, K-feldspar, biotite, igneous titanian andradite, titanite, and apatite as major phases (Lang et al. 1995).
The ZMP grades inward from pyroxenite, which forms the margin of the pluton, through melasyenite to a core of K-feldspar syenite (Lueck and Russell 1994). At the border of the pluton, pyroxenite forms lenses in calc-silicate rock, and to date five wollastonite localities have been found both within and peripheral to the ZMP.
Vishnevite-cancrinite occurs as cm-sized aggregates which weather white in pegmatitic syenite and is pseudomorphic after leucite (Lueck and Russell 1994). The pluton is cut by several different types of dykes, some of which have well-developed contacts with the 11 plutonic rocks, and others which have ambiguous contacts, such as porphyritic quartz
•if- dykes and diorite dykes respectively (Lueck and Russell 1994). Previous work by
Coulson et al. (1999) proposes that the ZMP is an alkaline intrusion of syenite and
pyroxenite formed from a mantle-derived magma with lowfo2 and <3si02. Coulson et al.
(1999) state that a single pulse of magma entered a shallow level chamber and that the source of the magma had affinities with arc-type magmas related to subduction. The parental magma began to fractionate clinopyroxene, then K-feldspar, resulting by physical sorting in side wall, marginal pyroxenite and roof zone syenite. The core continued to fractionate resulting in increased volatile contents and the crystallisation of feldspathoids. The residual magma buoyed to the roof and partly invaded the syenite to form vishnevite.
The pluton intrudes Paleozoic metasediments of the Stikine assemblage and
Triassic volcanics of the Stuhini Group (Jaworski and Dipple 1996). Wollastonite skarn
formation requires a calcite-rich protolith, a high Si02 content (either from the protolith
or from fluid infiltration), and one or both of high temperature and low C02 activity
(Jaworski and Dipple 1996). Even though the ZMP is silica undersaturated, the fluids carried enough dissolved silica to cause wollastonite skarn to form (as evidenced by the lack of calcite), but the critical factor for its formation was probably the high temperatures resulting from emplacement of syenite along with incorporation of marble xenoliths into the margin of the intrusion which would further increase the temperature
(Jaworski and Dipple 1996). Skarns result from extensive fluid infiltration into marble xenoliths within the pyroxenite border phase (Jaworski and Dipple 1996). The Paleozoic strata adjacent to the pluton are intensely metamorphosed and include calcsilicate and 12 marble (Jaworski and Dipple 1996). The calcsilicate is fine-grained, green, and contains diopside, grossular, biotite, titanian andradite, K-feldspar, and wollastonite (Jaworski and
Dipple 1996). The marble is light green to gray, is composed of recrystallised calcite, and represents a limestone protolith that was unreactive during metamorphism (Jaworski and Dipple 1996).
3.1.2 Sample Suite
Nineteen samples are used to represent the full spectrum of occurrence of titanian andradite at Zippa, including magmatic (in syenite, melasyenite, and pyroxenite), skarn, and dykes (Table 1). Sample locations are shown in Figures 2-5. From each sample a slab with representative mineralogy was cut and trimmed using a diamond saw and made into polished thin sections.
3.1.3 Whole Rock Geochemistry and Geochemical Methods
Whole rock geochemical analysis of plutonic rock samples was performed using fresh, uncontaminated samples. Rock chips were produced in a steel-faced crusher, and passed through twice to further reduce the chip size. The samples were subsequently powdered to about 200 mesh using a tungsten carbide shatter box. A total of nine magmatic samples from the ZMP were analysed for major and trace elements, ferric- ferrous iron, and water; Determined trace elements include Ga, Nb, Pb, Rb, Sr, Th, U, Y,
Zr. Geochemical data are listed in Table 2 along with calculated CIPW normative mineralogy. Major and trace elements, and loss on ignition (L.O.I.) were measured by
X-ray fluorescence spectrometry (XRF) at McGill University using an automated Phillips
PW 2400 spectrometer with a rhodium X-ray tube operating at 60kV, five X-ray detectors, five primary beam filters, eight analysing crystals, two fixed channels for 13 simultaneous measurement of Na and F, and a 102 sample autochanger. The precision for silica was within 0.5%, for the other major elements, within 1%, and for trace elements within 5%. Total iron was determined by X-ray fluorescence and FeO was determined using ammonium metavanadate titration. Water was determined at 105°C.
Ferrous detection limits were 0.01% and water detection limits were 0.01 and 1.0% for
+ H20' and H20 respectively.
The ZMP rocks are alkaline, except for one sample of pyroxenite which plots just inside the subalkaline field which is indicative of fractionation (Figure 6). The cumulus sample (1C-98-ZM39B) plots in the alkaline field (Figure 6a). All other samples are nepheline normative and have greater normative orthoclase. The AFM diagram
(Figure 6b) shows that the two pyroxenite samples and the cumulus sample are FeO enriched, whereas the other magmatic samples plot along a well defined trend from syenite, through trachytic syenite, to melasyenite with increasing FeO enrichment.
Pyroxenite samples which show FeO enrichment are indicative of fractionation and possibly contamination by hydrothermal calc-silicate rich fluids, as they are wollastonite and also diopside normative.
The trends for trace elements are shown in Figure 6c. Trends for Rb, Ba, and Sr trace elements show scatter. Other trace elements (e.g. Nb, Zr, and Y) show somewhat less scatter as most samples lie on a linear trend from syenite through pyroxenite. Y has
a negative correlation with Si02 for magmatic samples. ZM39B plots separately from the other samples and has more Nb, Zr, and Y (compatible), but less Sr, Rb, and Ba
(incompatible) than the other samples. Sr and Ba show large variations in concentration both between rock types and samples. 14
3.2 Petrography
3.2.1 Sample Description
This section starts with a description of the hand samples from the nineteen samples used in the present study. IC-98-ZM-42 is a dark green, medium grained pyroxenite containing pyroxene grains 3 to 4 mm in length. Minor (less than 10%) K- feldspar is also present. JC-98-ZM-26 is a gray, fine to medium grained pyroxenite with visibly zoned titanian andradite which range in size from 3 mm up to 1.3 cm in diameter.
Garnet is dark purple to black in color and sub- to euhedral. White calc-silicate composes about 10% of the rock and is usually found associated with the largest of the titanian andradite.
IC-98-ZM-8 is a medium grained, equigranular melasyenite containing up to 6 mm white to pink K-feldspar, up to 5 mm long green-black clinopyroxene laths, black, anhedral titanian andradite, and 5 mm biotite. IC-98-ZM-16 is very similar to ZM-8 with the exceptions that the feldspar is white to gray and the clinopyroxene is green in colour. Ti-andradite is smaller (up to 3 mm) and has a subhedral crystal habit.
IC-98-ZM-18 is a fine to medium grained syenite. K-feldspar is white to gray in colour and displays trachytic texture. Grains range in size from 2 to 4 mm. Mafic phases range in size from 1 to 5 mm, and include garnet and biotite. IC-98-ZM-27 is a medium to coarse grained syenite containing approximately 3% mafic phases comprised of 0.5 mm garnet and biotite grains. K-feldspar can be up to 1 cm in length and is pink to gray in colour. IC-98-ZM-43 is a gray, coarse grained syenite comprised of up to 2 cm-sized aggregates of vishnevite-cancrinite, K-feldspar, and titanian andradite.
IC-98-ZM-39 is a titanian andradite cumulus sample. The garnet are dense, 15 small (up to 2 mm in diameter), and euhedral. Some feldspar crystals are visible in the cumulate. The rock itself can be divided into two sections: the "B" part which is the garnet cumulus phase and the "A" phase which is a coarse grained syenite with feldspar laths up to 1 cm in length. The contact between the two phases ("C") is sharp and distinct with minimal overlap between the two.
Z95-6 is a sample of a magmatic dyke with up to 1.2 cm, euhedral titanian andradite which occur with interstitial K-feldspar and light green clinopyroxene. Z95-7 is a coarse grained sample of a magmatic dyke comprised of K-feldspar, light green clinopyroxene, and black, subhedral garnet up to 1 cm in size.
69ri/B66-5 is a porphyritic volcanic sample from the Crowsnest volcanics,
Alberta. This sample has been included in this study so that comparisons can be made between titanian andradite from a volcanic suite and those from primary magmatic samples. Black, euhedral titanian andradite crystals are up to 4 mm in size.
Z95-1 is a white to green coloured Glacier skarn which contains calc-silicate, clinopyroxene, and anhedral titanian andradite. The calc-silicate is embayed by the garnet. Z95-5 is composed of wollastonite and calc-silicate with chain garnet in the calc- silicate. Individual subhedral garnet grains are 1 mm in diameter, and can form cm long chains.
97BN1-4 and BN15-1 are from the Bartnick locality. 97BN1-4 is a coarse grained wollastonite skarn with light brown, euhedral, visibly zoned garnet. Garnet crystals can be up to 1 cm in diameter with visible zones up to 1 mm across. BN15-1 is a fine grained skarn which contains light brown, euhedral to subhedral chain gamet.
Individual, euhedral garnet can be up to 2 mm in diameter. No zoning is visible. 16
371 and 393 are from the Cliff skarn locality. Both samples consist predominantly of medium grained wollastonite, and K-feldspar. 371 has no visible garnet in hand sample, whereas 393 contains light brown, anhedral garnet up to 3.5 mm in diameter.
3.2.2 Petrography
Digital images of polished thin sections were obtained using a Polaroid
SprintScan 35 attached to an Apple Macintosh computer. Figure 7 shows images of the polished thin sections under plane polarised light. Table 3 summarizes the petrography described below.
Pyroxenite Samples
Pyroxenite samples include IC-98-ZM-42, IC-98-ZM-26. Both samples consist mainly of aegirine-augite clinopyroxene. Clinopyroxene is pleochroic clear to green and occurs as anhedral grains in groundmass, and as subhedral to euhedral phenocrystic grains. Titanian andradite occurs as a major phase only in ZM-26, where it is phenocrystic to megacrystic, euhedral, and some grains show visible zoning. In plane polarised light (PPL) under conventional optical microscopy, garnet is pale red-brown to dark brown in colour. Titanian andradite present in minor amounts in ZM-42 is interstitial and occurs with titanite. Apatite occurs in all pyroxenite samples and is colourless in PPL, has a euhedral to subhedral crystal habit, and displays first order birefringence. ZM-42 has apatite in major mineral amounts with euhedral grains included in pyroxene. Apatite occurs as fine grained groundmass in ZM-26. Titanite occurs as an accessory mineral in all pyroxenite samples. In sample ZM-42, titanite is interstitial, whereas in ZM-26 titanite is more abundant, grey to pale brown in PPL, fine 17 to medium grained, subhedral to euhedral, and displays first-order birefringence.
Abundant, small opaque inclusions litter the titanite. ZM-42 contains K-feldspar in accessory amounts. Groundmass in ZM-26 can be subdivided into two parts based on color and mineralogy: green, apatite-phiogopite-pyroxene-rich areas; and white calc- silicate areas composed of fine grained feldspars, epidote, and calcite surrounding large garnet crystals. Very minor opaque minerals occur in ZM-26 as inclusions in garnet and pyroxene.
Melasyenite Samples
Melasyenite samples include IC-98-ZM-8, and 1C-98-ZM-16. Both samples consist predominantly of K-feldspar, clinopyroxene, titanian andradite, biotite, and apatite. Euhedral titanite occurs in accessory amounts, and zircon occurs in very minor amounts included in other phases. K-feldspar displays some perthitic and vermicular texture and is partly altered to sericite and dusty opaques. Clinopyroxene is pleochroic pale green, occurs as anhedral grains, and is partly altered to dusty opaques. Titanian andradite is dark brown in colour and has an anhedral crystal habit. Biotite is orange to dark green in colour and has a subhedral crystal habit. Apatite is colourless in PPL, has a euhedral to subhedral crystal habit, and displays first order birefringence.
Syenite Samples
Syenite samples include IC-98-ZM-18, IC-98-ZM-27, and IC-98-ZM-43 and consist predominantly of K-feldspar, titanian andradite, biotite, with accessory pyroxene, and apatite included in K-feldspar. K-feldspar displays perthitic texture and is partly altered to dusty opaques, sericite, and epidote. Titanian andradite is dark brown in colour with subhedral to anhedral crystal habit. Biotite is anhedral and dark green to 18 brown in colour. Centimetre-size vishnevite-cancrinite aggregates occur in ZM-43 which are clear in PPL and hexagonal in shape. Anhedral muscovite occurs as a major phase in samples ZM-27 and ZM-18. Accessory euhedral titanite occurs in ZM-43, whereas ZM-
18 contains interstitial calcite and euhedral zircon included in K-feldspar. ZM-18 has some alignment of mafic phases and is trachytic, ZM-43 also has some alignment of mafic phases although the K-feldspar is not obviously trachytic, and ZM-27 shows no alignment or fabric.
Zippa Cumulus Sample
Samples 1C-98-ZM-39 A, B, and C represent three distinct parts of a cumulus garnet phase in coarse grained syenite. ZM-39A represents the syenite above and not in contact with the cumulus garnet, ZM-39B represents the cumulate garnet, and ZM-39C is the contact of the syenite phase with the cumulus garnet. ZM-39A consists predominantly of K-feldspar, biotite, and titanian andradite, with accessory apatite, euhedral titanite, and secondary epidote. K-feldspar shows some zoning and is partly altered to sericite and dusty opaques. Anhedral biotite is dark green in colour and is partly altered to chlorite. Titanian andradite is brown in colour, and has a subhedral to anhedral crystal habit, except for some fine-grained crystals included in K-feldspar that are euhedral. ZM-39B consists predominantly of titanian andradite, biotite, and K- feldspar, with accessory euhedral titanite and anhedral apatite. Two distinct generations of titanian andradite are discernable based on size: small euhedral garnet which lack inclusions, and phenocrystic, anhedral to subhedral grains which have biotite inclusions.
No zoning is visible in phenocrystic garnet whereas some zoning is visible in the smaller, euhedral grains. Biotite is dark green in PPL and exists in two generations: large 19 euhedral (minor anhedral) biotite in contact with pyroxene and K-feldspar in the groundmass, and garnet inclusions. Biotite shows minor alteration to chlorite. K- feldspar is partly altered to dusty opaques. At the contact between the two phases in ZM-
39C skeletal garnet is present in the syenite phase and is replaced by biotite, epidote, and pyroxene.
Zippa Magmatic Dykes
Z95-6 and Z95-7 are magmatic dykes. Major minerals include K-feldspar, titanian andradite, clinopyroxene, and euhedral to elongate apatite. Interstitial calcite and anhedral mica occur in Z95-6. K-feldspar is perthitic in texture and partly altered to dusty opaques in both samples. In addition, K-feldspar in Z95-6 is interstitial between garnet grains and displays some vermicular texture. Titanian andradite in both samples is light to dark brown in colour, euhedral to subhedral in habit, but is visibly zoned in only Z95-6. Titanian andradite in Z95-7 may be embayed with pyroxene or K-feldspar.
Clinopyroxene is clear to very pale green in colour, displays subhedral crystal habit, and is partly altered to epidote and dusty opaques.
Crowsnest Volcanic Sample
69WB66-5 is a pristine volcanic sample of the Crowsnest volcanics rich in euhedral titanian andradite. Garnet crystals are green to brown in colour, visibly zoned, and contain fine grained clinopyroxene inclusions. Major K-feldspar is euhedral, shows some zoning, and displays minor perthitic texture. Clinopyroxene is dark green in colour and has a subhedral to anhedral crystal habit. Plagioclase is fine grained and anhedral.
Accessory titanite is euhedral and commonly twinned. Minor opaques are also present. 20
Glacier Skarn Samples
Z95-1 and Z95-5, both Glacier skarn samples, consist of titanian andradite, K- feldspar, clinopyroxene, calcite, and euhedral apatite. Anhedral wollastonite is present in both samples; in major amounts in Z95-5, and in accessory amounts in Z95-1.
Titanian andradite is dark brown to red, shows no visible zoning, is littered with inclusions and, in Z95-5, deeply embayed by calc-silicate. K-feldspar and calcite occur as interstitial grains. Clinopyroxene is light green in colour, partly altered to epidote, and can occur as either large euhedral crystals typically with anhedral titanian andradite inclusions, or itself as anhedral inclusions in other phases.
Bartnick Skarn Samples
Bartnick skarn samples (97-BN-1-4 and BN-15-1) predominantly consist of titanian andradite, anhedral wollastonite, anhedral clinopyroxene, and anhedral K- feldspar and calcite. Accessory apatite is present in BN-15-1 and the sample shows minor alignment of phases. Titanian andradite is very pale brown in colour, euhedral to subhedral, and has visible zoning in 97-BN-1-4 as well as anisotropic zones in some crystals.
Cliff Skarn Samples
The Cliff skarn samples (371 and 393) consist predominantly of anhedral wollastonite, perthitic K-feldspar, and interstitial calcite, with accessory euhedral apatite and titanite. Light brown, anhedral titanian andradite occurs in 393, but is only found as very minor interstitial grains in 371. Clinopyroxene occurs as subhedral grains intergrown with K-feldspar in sample 371. 21
3.2.3 Scanning Electron Microscopy
Scanning electron microscopy was used in conjunction with the optical microscope to further identify and characterise phases (e.g. small grains and inclusions).
Thin section traverses were selected by optical microscope. Thin sections were carbon- coated and a strip of copper tape attached to promote electron flow across the sample.
Qualitative energy-dispersion X-ray spectrometry (EDS) was done on a PHILIPS XL30 scanning electron microscope equipped with a Princeton Gamma Tech ultrathin window detector. Compositional variation in the samples was studied using digital backscattered electron (BSE) images.
Titanian andradite zoning not visible with the naked eye or in thin section was observed in BSE images. Figure 8 A-D show titanian andradite grains from all sample groups which display zoning. For each sample, different grains have been identified using different letters, and different areas on the same grain also have a number. The letters correspond to all grains, not only garnet, selected by optical microscopy for SEM and EPMA study. Qualitative EDS analysis of zoned garnet grains shows differences in
Ti, Fe, and Al between zones. Figure 8A shows zoning visible using BSE imaging for
Zippa magmatic samples. All magmatic samples display irregular zoning with the exception of several pyroxenite grains (diagrams a,c,d) which also show some regular zoning. Figure 8B shows zoning from the Zippa cumulus and Crowsnest volcanic samples. Cumulus garnet (ZM-39C) displays a combination of regular and irregular zoning in all garnet observed, with the most irregular areas concentrated in the cores.
The Crowsnest volcanic garnets commonly have a well defined core which has irregular zoning, but from the core edge to the rim displays very regular zoning. Figure 8C shows 22
zoning from both Zippa dykes samples. The magmatic dyke samples show both regular
(Z95-6) and irregular (Z95-7) zoning. Z95-6 is shown in diagrams a-f whereas Z95-7 is
shown in diagrams g-i. Figure 8D shows zoning from the Zippa skarn samples. Most
skarn samples are very irregularly zoned, with the exception of 97BN1-4 (diagrams g-r)
which has very regular zoning coupled with irregular zones inside otherwise regular
zones. Complex, non-periodic zonation patterns of this sort can be the result of periodic
external forcings, notably changes in the composition of the hydrothermal fluid (Jamtveit
1991). Some parts of certain crystals in 97BN1-4 also display sector zoning (diagrams
g,ij) and anisotropy.
Element maps, produced using SEM/EDS and characteristic X-ray lines, have
been used to show element zonation and growth zoning in garnet (Nakano et al. 1989).
Element maps of ZM39B-B, a small, euhedral, optically zoned garnet, are shown in
Figure 9. Figure 9-a shows the grain as a back-scattered electron image. Most elements
show little to no discernable zoning with this method, with the exception of Figure 9-f
which shows titanium zoning. Titanium is brightest (yellow) at the centre indicative of
- large amounts, and colour decreases toward the rim which indicates lesser amounts. No
other grains tested show discernable zoning with this method. 23
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XZ © © © X) TJ © "8 CO 3 © x: x: © © © S>x : x: c 3 js X) c CO x: © E 3 © © CO CO 3 x: x: E* © C 3 C CO © CO ^ c CQ O o CO CD O CO CO CO S © N CO X> CO 81 S if) If) o CD CD CD i N I- N N CO 42 CD 00 c o '55 | c5 '55 c o CD 8 1! « >> c 8 >. x: CO s x> O) I E CD TJ ID c >. «= CL CD c 8 CD CO W TJ CO TJ ro c ca 5 c TJ CD xCD: c 1 2 2 |(0 ro TJ x: t X? sz c © g-i c CO X) 12 ro CO LO LO LO co cn z CO N CO CO Figure 8A. BSE images of grains showing zoning in Zippa magmatic samples. a-e) pyroxenite; f-g) melasyenite; h-o) syenite. 44 Figure 8A. Continued. Figure 8A. Continued. 46 Figure 8B. BSE images of grains showing zoning in Zippa cumulus and Crowsnest volcanic samples, a-k) cumulus; l-r) Crowsnest. 47 IC-98-ZM-39C-I IC-98-ZM-39C-W Figure 8B. Continued. 48 69WB66-F 69WB66-G Figure 8B. Continued Z95-6-M Z95-6-Mcloseup w Z95-6-P1 Figure 8C. BSE images of grains showing zoning in Zippa dyke samples. Figure 8C. Continued. Figure 8D. BSE images of grains showing zoning in Zippa skarn samples. a-f) Glacier; g-r) Bartnick; s-u) Cliff. 52 Figure 8D. Continued. 53 Figure 8D. Continued. Figure 8D. Continued. 55 Figure 9. SEM elemental X-ray maps for IC98ZM39B grain b. a) BSE image; b) Si; c) Ca; d) Fe; e) Al; f) Ti. 56 Chemical Characteristics and Representation of Titanian Andradite 4.1 Chemical Mineralogy 4.1.1 Electron Microprobe Analyses Compositions of garnet were determined using a Cameca SX 50 electron microprobe. Operating conditions were 15 kV and 20 nA beam current. Estimates of analytical uncertainties are described in Appendix A. Compositions were measured for all textural varieties of garnet, including phenocrysts, smaller euhedral garnet, and interstitial grains. Garnet samples were also chosen for analysis on the basis of zoning that was visible under optical microscopy or during BSE imaging. Straight-line traverses were performed on individual grains and, where possible, multiple grains were analysed within a single sample. Traverses from core to rim were done where possible, however slight deviations from a straight-line were sometimes necessary to avoid inclusions or flaws in the grain. Garnet compositions were converted to structural formulae and Thompson components using Matlab script ti and.m (Appendix B). The program assumes eight cations and twelve oxygens and on that basis calculates iron valences. Cation distributions over the X, Y, and Z sites are forced, within the program, to totals of approximately 3, 2, and 3, respectively. 4.1.2 Zoning Observed in Microprobe Analyses Representative median microprobe analyses with their corresponding structural formulae and Thompson components are given in Table 4. For full microprobe analyses, structural formulae and Thompson components, inclusions, and bad or unknown analyses 57 (in Excel 4.0), see cd-rorri in Appendix C. The process of eliminating inclusions, bad analyses, and unknowns from the microprobe data is described below. Inclusion analyses that were intentionally spotted and probed were removed from the general data into a separate table labeled "Inclusions". The elimination process for "bad" data included analyses that: a) were taken too near the edge of a grain or pit or crack, b) have an abnormal ion distribution (ie. not the 3-2-3 site distribution), c) have either very low ion totals or ion totals greater than 8, d) represent other mineral compositions that were not spotted, or e) have oxide totals outside of the accepted 101 -99 ± 3 wt.% range. The low value of 96, wt.% was established as a cut-off to avoid eliminating any analyses which contain large amounts of water, though this total for a non-hydroxyl-rich garnet analysis would normally be considered to be too low. Figure 8A-D contains back-scattered electron images of zones that were analysed. Zoning is described in terms of grain by grain patterns within a sample, patterns common to different rock types, patterns in calculated structural formulae, and patterns common to different environments of formation. Oxides which are excluded from this discussion show no significant zoning. "Major" oxides refer to those oxides present in the samples in the greatest abundance, including Si02, Ti02, A1203, Fe203, and CaO. Compositional profiles for selected grains (Figures 10-24) show zoning in most of the major oxides. The lines along which compositional profiles were constructed for selected grains are shown in Figure 25. Compositional profiles for ZM39C (Figures 10-16) are described below. In ZM39B, grains a and h (Figures 10 and 11), high Si02 content correlates with high Fe203, 58 and low Ti02 and A1203. In grains i, n, w, and x (Figures 12, 13, 15, and 16), Ti02 shows reverse zoning (decreases from core to rim), and high Ti02 content correlates with low MnO content. In grain n, A1203 and Fe203 are negatively correlated, and in grain x, low Ti02 content correlates with low Fe203, and high A1203 and Si02 contents. Figure 15 shows a low SiOz peak which corresponds to a low total oxides peak which may indicate the presence of OH. In grain o (Figure 14), high Si02 correlates with high A1203 and CaO, and low Ti02 and Fe203. Compositional profiles for 69WB66-5 (Figures 17-20) show that Ti02 has pronounced oscillatory zoning in all but grain e (Figure 18), in which it shows normal zoning (increases from core to rim). In grains e and p (Figures 18 and 20), high Ti02 content correlates with low Fe20, content, whereas in grain b (Figure 17) high A1203 content correlates with low CaO content. Compositional profiles for Z95-5 (Figures 21 and 22) show that both Ti02 and Si02 show oscillatory zoning and that these pattens are opposite. In Z95-5, grain f (Figure 21), high Si02 content correlates with high A1203 and CaO and low Ti02 content. Compositional profiles for 97BN1-4 (Figures 23 and 24) show that high Ti02 content correlates with high Fe203 and low A1203 and CaO contents. In grain b (Figure 23) high Si02 content correlates with high A1203 and CaO contents; and low Si02 content corresponds to a low total oxides content which may indicate the presence of OH. Zoning patterns within rock types Table 5 summarizes the zoning patterns for each sample described below. Chemical zoning in titanian andradite from pyroxenite typically shows regular zoning in which darker zones have more A1203 (and Ti02 in one grain) and less Fe203. 59 Decreases of wt.% in Ti02 are accompanied by proportional increases in Fe203 for most grains, and Fe203 shows the opposite overall zoning pattern to the other major oxides. Most subhedral melasyenite titanian andradite grains show no zoning in BSE however, those few that do show irregular zoning contain darker areas which have more Ti02 and less Fe203 wt.% than do light areas. Changes in TiOz wt.% may be accompanied by inversely proportional or proportional changes in Fe203, and slight increases in A1203 for interstitial grains, but slight decreases for subhedral grains. Fe203, whether reverse or normal, shows the opposite overall zoning pattern to the other major oxides. Ti02 and A1203 may show opposite oscillatory zoning patterns, A1203 and CaO may show opposite oscillatory zoning patterns, or A1203 and Fe203 show opposite oscillatory zoning patterns. Zoning patterns observed in subhedral, anhedral, and interstitial titanian andradite syenite grains include irregular zoning near rims. Dark zones show larger values of Ti02 and A1203 and lesser values of Fe203 than do lighter zones. Ti02 and Fe^ show the same oscillatory zoning pattern, but opposite to that of A1203. CaO shows the same zoning pattern as A1203 in some grains. Overall from core to rim, A1203 and CaO commonly have reverse zoning, whereas Ti02 and Fe203 show normal zoning, though Ti02 may instead show the opposite overall zoning pattern from core to rim as compared to other major oxides. In most grains, A1203 changes by approximately half that of the Ti02 change from point to point, however in some grains AI203 and Fe203 change with nearly the same rate from point to point. Zoning patterns observed in subhedral to anhedral, and euhedral titanian andradite cumulus grains include irregular zoning near the core and regular zoning near 60 the rim in BSE. Darker areas have larger amounts of Ti02 and A1203 and lesser amounts of Fe203 than do lighter zones. A1203 and CaO show the same oscillatory zoning pattern, opposite to that shared by Ti02 and Fe203. Compositional profiles show that Si02 shares the same oscillatory zoning pattern as A1203 and CaO. From core to rim, either Fe203 or A1203 shows the opposite zoning pattern as compared to the other major oxides. Ti02 and Fe203 change in wt.% by approximately the same amount from point to point for two grains, and A1203 changes by some fraction of the other two. The majority of magmatic dyke titanian andradite grains show no visible zoning in BSE. Zoning patterns observed in subhedral to anhedral, or parts of larger, magmatic dyke grains include irregular zoning near the rim in which darker zones have more A1203, but may have either more or less Ti02, and more or less Fe203 than lighter zones. Regular zoning is found in half the grains and has darker zones which show more Al203, less Fe203, and either more or less Ti02 than light zones. For most grains, Ti02 and Fe203 show the same oscillatory zoning pattern, as do AJ203 and CaO but opposite to the pattern of Ti02 and Fe203. However, in several grains A1203 and Fe203 show the same oscillatory zoning pattern, which may be the opposite pattern of either Ti02 or CaO. Fe203 shows reverse overall zoning. Several grains show that A1203 and Fe203 change by approximately the same wt.% from point to point, and Ti02 changes by either the same or half that amount. Zoning patterns observed in subhedral to euhedral volcanic titanian andradite grains include regular zoning in which darker areas show more Ti02 and A1203 and less Fe203 than lighter areas, and irregular cores which are visible optically. In one grain, Ti02 and CaO have the same oscillatory zoning pattern, and in compositional profiles 61 Ti02 and Fe203 have opposite oscillatory zoning peaks. From core to rim Ti02 shows reverse zoning whereas Fe203 shows normal zoning. The change in wt.% from point to point for Ti02 is twice the wt.% change for Fe203. Anhedral titanian andradite grains from the Glacier locality contain abundant inclusions and commonly show no zoning in BSE, however those that do show irregular zoning in BSE have darker zones which show more A1203 and less Fe203 and Ti02 than lighter zones. Ti02 and Fe203 share the same oscillatory zoning pattern, as do A1203 and CaO, opposite to that of Ti02 and Fe203. Overall from core to rim, whether normal or reverse, Ti02 and Fe203 have the same zoning pattern, and A1203 and CaO share the same pattern, opposite to Ti02 and Fe203. Al203 and CaO change in wt.% by approximately the same amount from point to point, whereas in most grains the change in wt.% for Fe203 and Ti02 from point to point is either half or approximately the same. The two Bartnick samples have entirely different titanian andradite grain and zoning types. 97BN1-4 has coarse grained, euhedral grains which contain abundant inclusions, and have fine regular zoning with darker zones which show more A1203 and less Ti02 and Fe203 than lighter zones. Ti02 and Fe203 have the same overall zoning pattern, and A1203 and CaO share the same pattern, opposite to Ti02 and Fe203. A1203 and Fe203 consistently change in wt.% by approximately the same amount from point to point. BN15-1 has sub-anhedral grains which contain abundant inclusions, and have irregular zoning in which darker zones for anhedral grains show more A1203 and Ti02 and less Fe203 than lighter zones, whereas subhedral grains show more A1203 and less Ti02 and Fe203. Zoning patterns observed in anhedral titanian andradite Cliff grains show irregular zoning in which darker zones show more A1203 and less Ti02 and Fe203 than lighter zones. Commonly, A1203 and CaO share the same pattern, opposite to Ti02 and Fe203. Interstitial grains show irregular zoning in which darker zones have more A1203 and Ti02 and less Fe203, and from core to rim Ti02 and A1203 have the same overall reverse zoning pattern whereas Fe203 and CaO share the same pattern, opposite to Ti02 and A1203. Zoning patterns within different environments Across the sample suite, no systematic trends in zoning occur with respect to brightness in back-scattered electron images, however within different environments of formation trends do occur as described below. Partly resorbed, euhedral volcanic grains are considered the most primary of the grains in this study. Cumulus grains, though not resorbed, share many similarities with the volcanic grains (from Crowsnest) including euhedral to subhedral shape; irregular zoning near the core and regular zoning near the rim in which darker zones show more Ti02 and A1203 and less Fe203 than lighter areas; A1203 and CaO have the same oscillatory zoning pattern, opposite to that shared by Ti02 and Fe203; and the change in wt.% from point to point for Ti02 is either the same or twice the wt.% change for Fe203. Syenite grains also possess these early-formed characteristics, however A1203 changes by approximately half that of the Ti02 change from point to point, whereas in some grains A1203 and Fe203 change wt.% with nearly the same rate from point to point. Melasyenite grains generally show no zoning, or show irregular zoning, in which darker zones have more Ti02 and less Fe203 wt.%. Ti02 and A1203 show opposite oscillatory zoning patterns, A1203 and CaO show opposite oscillatory zoning patterns, or A1203 and 63 Fe203 show opposite oscillatory zoning patterns. Changes in Ti02 wt.% may be accompanied by proportional increasing or decreasing changes in Fe203, and slight increases in A1203. Pyroxenite grains show only regular zoning in which darker zones have more A1203 and less Fe203, but show no change in Ti02. Decreases of wt.% in Ti02 are accompanied by proportional increases in Fe203. Magmatic dykes show either regular or irregular zoning in which darker zones have more A1203, but may have either more or less Ti02, and more or less Fe203 than lighter zones. Ti02 and Fe203 may show the same oscillatory zoning pattern however, AI203 and Fe203 may also share the same zoning pattern, as may Ti02 and CaO. In summary, as crystallisation progresses, the grains begin to lose more and more, or to retain only certain parts, of the early zoning characteristics, however, all magmatic grains do indicate substitution and possibly replacement between Ti02, Fe203, and A1203. Except for Cliff samples and Z95-1, skarn samples have a larger content of Al203 (up to 22 wt.%) and therefore have a larger grossular component than magmatic garnet. Cliff samples have more A1203 than magmatic samples but less than other skarn samples, and have the most properties in common with, and are also physically closest to, syenite magmatic samples. Cliff samples show irregular zoning in which darker zones have the same properties as early formed magmatic zones; A1203 and CaO have the same oscillatory zoning pattern, opposite to that shared by Ti02 and Fe203; and the change in wt.% from point to point for Ti02 is either the same or twice the wt.% change for Fe203. Cliff samples likely formed from early fluids driven off the pluton. Skarn with larger grossular components likely formed from infiltration of later and likely more evolved plutonic fluids, as they possess similar characteristics to later magmatic stages 64 including irregular to regular, or the absence of, zoning; darker zones which show more A1203, and less Ti02 and Fe203 tnan lighter zones; Ti02 and Fe203 share the same oscillatory zoning pattern, as do A1203 and CaO, opposite to that of Ti02 and Fe203. In summary, Cliff samples formed from early formed plutonic fluids, Bartnick sample BN15-1 was intermediate as it contains properties common to both Cliff and other skarns, whereas Bartnick sample 97BN1-4 was likely the last to form from more evolved fluid, owing to its large euhedral grains, zoning similar to later magmatic samples, and properties such as anisotropism and twinning which are not found in other samples. 4.2 Representation of Analyses Thompson space representation expresses mineral analyses as end-member mineral chemical formula with variable exchange components (Russell et al. 1999). The twelve linearly independent components used to describe garnet compositions from this study include the additive component andradite, and eleven exchange components: AlFe(3+h CrFe(3+)-, FeMg-, H4Si-, MgCa-, MnCa-, NaFe(3+)2Ca-, TiMgFe(2+)-, TiSi-, VFe(3+)-, and ZrSi-. For a complete discussion on how to convert to Thompson components, see Appendix B in Russell et al. (1999). Thompson component representation readily discriminates between titanian andradite derived from magmatic vs. hydrothermal environments, as different substitution mechanisms operate in different environments (Russell et al. 1999). Magmatic garnet always has zero H4Si- and positive FeMg-, whereas hydrothermal garnet always has zero FeMg- and positive H4Si- (Russell et al. 1999). Russell et al. (1999) state that Ti in hydrothermal andradite is expressed as TiSi- and exploits deficiencies at the tetrahedral site, whereas igneous titanian andradite 3+ contains both TiSi- and TiMg[Fe ].2 and uses coupled substitutions involving octahedral 65 cations. The exchange components do not directly represent crystallographic substitution mechanisms (Russell et al. 1999); however, the values of those components which represent the only exchange mechanism by which an element can enter the formula are equivalent to the number of atoms per formula unit, whereas two exchange components involving the same substitution (eg. Ti) do not represent an equivalent number of atoms per formula unit. Ca is used as a linearly dependent component and should be zero for all analyses. For those analyses which have non-zero values, the implication is that the Ca component is not redundant and that these garnet would lie in another compositional space, possibly grossular space, as compared to the titanian andradite space. The andradite component is always perfect at 1.000. The norm of the vector of exchange components provides an idea of how far the analysis is from the true andradite composition which is an exact zero value. The norm of each analysis is determined by squaring each component (excluding the andradite component), adding all those values together, then taking the square root of the sum of squares. The norms of the vector for all of the magmatic samples (as shown in Table 4), including the two dykes, are less than one. All magmatic samples have varying amounts 3 of both TiSi- and TiMg[Fe "].2, zero residual Ca, negative MgCa- component, very small H4Si- component, and positive FeMg-. The pyroxenite sample ZM26 shows more skarn-like component values especially near edges and cracks in crystals, therefore these reflect infiltration of a late- stage skarn fluid and do not reflect the original pyroxenite values. The H4Si- component values for ZM26 are quite low (less than 0.06), as compared with skarn H4Si- values, but 66 are accompanied by zero FeMg- components. The melasyenite sample ZM8 for some analyses (randomly distributed across several grains) has a large H4Si- component (up to 0.09) and zero FeMg-. ZM16 has a zero or slightly positive MgCa- component, randomly distributed across several grains and across several BSE-visible zones. Syenite sample ZM18 has some very large amounts of H4Si- component, up to 0.16, and zero FeMg- component, mainly located on rim analyses, as does ZM43 with amounts up to 0.32, and ZM39A has values up to 0.17. ZM27 predominantly has non- negative MgCa- components, and ZM39A also has some non-negative MgCa- components. Larger H4Si- components at the rims may indicate infiltration of mid-stage skarn fluid. The cumulus garnet sample ZM39B has predominantly negative MgCa- component, but also has many non-negative values (up to 0.05), whereas WB66-5 has positive MgCa- components (up to 0.11). The volcanic analyses have exactly zero H4Si- for all points (and positive FeMg- values), whereas ZM39B shows some slightly elevated H4Si- amounts up to 0.10, consistently located on grain rims and accompanied by zero FeMg-. The magmatic dyke samples predominantly show small norm values but also have several values of one or over, and zero or slightly positive FeMg-. Z95-7 has many large values of H4Si- component (up to 0.2), whereas Z95-6 also has some large values of H4Si-, but these are less common than in Z95-7, and are accompanied by large norm values. In both samples, larger H4Si values are located near cracks, in dark zones, and near rims of grains, however entire grains may display these values where crisscrossed by 67 small cracks. Cliff samples also have norms less than one and therefore share yet another property with the magmatic samples, whereas most other skarn samples have norms greater than one. The Cliff and Glacier Z95-1 samples generally have equal amounts of 3+ both TiSi- and TiMg[Fe ].2, zero residual Ca, negative MgCa- component, zero or positive FeMg-, and small or zero H4Si- component, except for several points in both rock types which have large H4Si- components located near cracks or rims. The Glacier calc-silicate sample and the Bartnick BN15-1 have intermediate norms greater than one, whereas 97BN1 -4 has the largest norm (1.63) and is therefore furthest in composition from a true andradite. The two samples with the largest norms (Z95-5 and 97BN1-4) also have some of the largest values for the MgCa- component, up to 0.04. All three samples show zero residual Ca, relatively no average TiMg[Fe3+]_2, predominantly positive MgCa- component, zero or positive FeMg-, and a mixture of both small and large (up to 0.20) H4Si- components where large values are located at points in dark zones, near cracks, and sometimes at the rim. Figure 26 illustrates the division between magmatic and skarn samples and also the more subtle divisions which exist within some sample types in terms of TiSi- and 3+ TiMg[Fe ].2 exchange components. Igneous samples have greater quantities of both 3+ TiSi- and TiMg[Fe ].2, zero H4Si- and positive FeMg-, whereas true hydrothermal 3+ samples plot in the negative quadrant for both TiMg[Fe ].2 and FeSiMgH4 (FeMg- component minus the H4Si- component) (Russell et al. 1999). Skarn samples plot between the two extremes. The two pyroxenite samples plot separately, especially in terms of the AlFe- component, likely indicative of skarn fluid infiltration in ZM26 as 68 other skarn samples plot in the same position. However, the two samples may have a slightly different origin. As suggested by Coulson et al. (1999), in addition to the pyroxenite border phase, there may exist two additional pyroxenite units one of which originated from a liquid not a crystal mush and occurs as fine-grained dykes, whereas the other unit consists of large tabular bodies that contain stringers of calc-silicate. Though neither sample is reported as a dyke, the possibility of different origins should not be discounted as ZM42 is finer grained and ZM26 contains some calc-silicate. The melasyenite samples also plot independently of one another also likely as a result of skarn fluid infiltration which has affected ZM16 more than ZM8, as ZM8 shows larger 3+ amounts of both TiSi- and TiMg[Fe ].2, and plots lower on the AlFe(3+)- diagram. The dyke samples also show evidence of minor skarn fluid infiltration and some points plot quite high on the AlFe(3+)- diagrams. However, both dyke samples are clearly magmatic 3+ as both have large values of both TiSi- and TiMg[Fe ].2. The two Glacier samples plot separately, especially in terms of the AlFe(3+)- component. Z95-1 exhibits a stronger magmatic affinity with larger amounts of both TiSi- and TiMgfFe34].^ and smaller AlFe(3+)- components. Some points for Z95-5 plot in the lower left quadrant on the FeSiMgH4 diagram which is indicative of more true hydrothermal affinities. Both Bartnick samples show stronger hydrothermal affinities than do other skarn samples and 3+ have almost zero or negative TiMg[Fe j\2, large AlFe(3+)- components, and some points (mostly from BN1-4) plot in the lower left quadrant on the FeSiMgH4 diagram. Those points, such as BN1-4, which are "more hydrothermal" than other skarn samples, but do not plot as low in the lower left quadrant on the FeSiMgH4 diagram as "true hydrothermal" samples (as defined by Thompson component work by Russell et al. 69 (1999)), will hereafter be referred to as hydrothermal. Cliff samples both show magmatic affinities. 371 plots very low and slightly apart from 393 on the AlFe(3+)- diagram. Figure 27 further illustrates the division between magmatic, skarn, hydrothermal, and dyke samples in terms of Thompson components. The Zippa igneous samples fall into two groups: those points which have not been infiltrated by skarn fluid; and those points which have been infiltrated, in which case these points plot higher on the AlFe(3+)- diagram and near the lower left quadrant on the FeSiMgH4 diagram. The dykes plot mainly between the two igneous groups. The skarn samples plot between 3+ igneous, rich in both TiSi- and TiMg[Fe ].2 components, and hydrothermal affinity, for which points plot in the lower left quadrant on the FeSiMgH4 diagram. The range is best seen on the AlFe(3+)- diagram in which three groups of skarn are discernable. Those samples richest in the AlFe(3+)- component are hydrothermal and plot near the top of the diagram, skarn samples intermediate between magmatic and hydrothermal affinities plot in the middle of the diagram, whereas those skarn samples closest in affinity to the igneous samples plot near the bottom with varying amounts of the TiSi- component. In summary, magmatic samples show small norms, negative MgCa- components, 3+ very small H4Si-, positive FeMg- components, and contain both TiSi- and TiMg[Fe ].2 components; whereas hydrothermal samples predominantly have positive H4Si-, zero to slightly positive FeMg-, norms greater than one, and Ti expressed mainly as the TiSi- component only (Figure 28). Skarn samples are more similar to the magmatic samples (which plot furthest left on Figure 28f), although some skarn samples show component characteristics intermediate between the magmatic and "true" hydrothermal extremes '70 (which plot furthest right on Figure 28f). Magmatic dykes have experienced skarn fluid infiltration as these samples show zero to slightly positive FeMg-, and predominantly show a large H4Si- component. Oxygen fugacity and silica activity Titanian andradite compositions reflect/^ conditions at the time of formation (Virgo et al. 1976a), specifically a strong correlation exists between increasing 3+ TiMg[Fe ].2 component and decreasing fQ2, and TiSi may be considered a proxy for asi02 (Russell etal. 1999). Russell et al. (1999) state that the ZMP evolved to a higher fQ2 state in conjunction with the evolution of a fluid phase, and that skarn samples inherit fQ2 from the magmatic fluid but have an increased aSiQ2 as a result of cooling of magmatic volatiles and interaction of the fluid with quartzite. Low/^ values for titanian andradite are indicative of crystallisation at high pressure, however H2 diffusion and sulphur loss are two mechanisms which can result in pressure, and consequently^, changes (Virgo et al. 1976b). Natural garnet become more and more silicon-deficient with increasing fQ2 (Huckenholz et al. 1976). Data from this study as shown in Figure 27 (TiSi- vs. 3+ TiMg[Fe ].2 plots) concur with these findings and show that the igneous samples show lower fQ2 (i.e. they plot higher on the TiSi- vs. TiMgFe- diagram) and lower asj02 than the skarn and hydrothermal samples which plot closer to the origin, indicative of crystallisation at higher fQ2 values from a more evolved fluid. asio2 is also increased in the skarn samples, also indicative of evolution of the original magmatic fluid to a slightly 3+ more oxidizing fluid (negative TiMg[Fe ]_2) and is even more increased in the hydrothermal samples. Dykes show some effects of interaction with both the original 71 fluid (low <2Sio2) and a slightly more evolved fluid (higher aSi02 andf02), but show almost no indication of interaction with the highly evolved hydrothermal fluid which shows the highest asi02 and/o2 signature. 4.3 Summary Five different titanian andradite types are identified on the basis of zoning and Thompson components which include: magmatic "A" or primary magmatic samples which include ZM39B and WB66-5; magmatic "B" which include most magmatic samples (e.g. ZM16); skarn "A" which can be further subdivided into two groups including Cliff samples which show a magmatic affinity in chemical zoning (e.g. 371), and most other skarn samples excluding BN1-4 (e.g. Z95-1) which grade between skarn "A" and skarn "B"; skarn "B" consists of only the hydrothermal sample BN1-4; and dyke samples which have a magmatic signature overprinted by skarn "A" fluids (e.g. Z95-6). 72 QQ O CO LO O -t- LO OO LO LO LO LO o LO CO o CD oo co T- O t>- i CM LO co CN co o co OO CM CN O CM O O LO o o o cp o o o CO CD d d CN d od CM d d d d d d d d CM 2 wlco CN CO CD Nco u<5CD 3 CD CN T- CD LO oo CO CN oo r- 00 CO o CD o CN o CO 00 T- CD O T— CM oo CN CD CO CN O 5) 00 CM O CM O O LO CM o od CM o o o cp o o CM to CM d d 00 d CD d d d d d d d d N 00 o O CD CM o CD CD CD O o CM o S O oo oo CD o o T— O O co CO o 00 o 00 O O o r>- o o o T— CO O T- d CN ob CM CM CM d d 00 d CD d d d d d d o d 5 CD O CO N. 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J- CO CO T co CD J= co ro -^r 7- o o t !± 11£ 1 N < O > f— LL 2 I 76 G 400 0 400 Microns from core Microns from core Figure 10. Compositional profiles for ZM39C, grain a. Oxides are in wt%. Error bars represent 2S analytical uncertainty. 77 Total oxides 34 ZrO2 _ 0 4 CaO 32 ^^^JLj. 30 1.2 MnO 0.8 0 400 0 400 Microns from core Microns from core Figure 11. Compositional profiles for ZM39C, grain h. Oxides are in wt%. Error bars represent 2S analytical uncertainty. 78 Figure 12. Compositional profiles for Zm39C, grain i. Oxides are in wt%. Error bars represent 2S analytical uncertainty. 79 Total oxides CaO 32 MnO 0.8 28 Fe203 24 20 0 400 0 400 Microns from core Microns from core Figure 13. Compositional profiles for ZM39C, grain n. Oxides are in wt%. Error bars represent 2S analytical uncertainty. 80 Figure 14. Compositional profiles for ZM39C, grain o. Oxides are in wt%. Error bars represent 2S analytical uncertainty. 81 Total oxides 34 CaO 32 Mn0 0.8 0 400 800 0 400 800 Microns from core Microns from core Figure 15. Compositional profiles for ZM39C, grain w. Oxides are in wt%. Error bars represent 2S analytical uncertainty. 82 0 400 0 400 Microns from core Microns from core Figure 16. Compositional profiles for ZM39C, grain x. Oxides are in wt%. Error bars represent 2S analytical uncertainty. 83 Figure 17. Compositional profiles for 69WB66-5, grain b. Oxides are in wt%. Error bars represent 2S analytical uncertainty. 84 0 400 0 400 Microns from core Microns from core Figure 18. Compositional profiles for 69WB66-5, grain e. Oxides are in wt%. Error bars represent 2S analytical uncertainty. 85 8 100 A1203 4 Total 96 oxides 0 92 0.8 36 ZrO204 CaO 32 1 0 28 6 1.5 Ti02 A MnO 0.5 40 28 Si0236 Fe203 24 32 20 0 400 800 0 400 800 Microns from core Microns from core Figure 19. Compositional profiles for 69WB66-5, grain n. Oxides are in wt%. Error bars represent 2S analytical uncertainty. 86 Figure 20. Compositional profiles for 69WB66-5, grain p. Oxides are in wt%. Error bars represent 2S analytical uncertainty. 87 Figure 21. Compositional profiles for Z95-5, grain f. Oxides are in wt%. Error bars represent 2S analytical uncertainty. 88 Figure 22. Compositional profiles for Z95-5, grain I. Oxides are in wt%. Error bars represent 2S analytical uncertainty. 89 Figure 23. Compositional profiles for 97BN1-4, grain b. Oxides are in wt%. Error bars represent 2S analytical uncertainty. 90 34 0.4 MnO 0.2 ! 40 Si02 36 32 1 r 0 500 1000 0 500 1000 Microns from core Microns from core Figure 24. Compositional profiles for 97BN1-4, grain c. Oxides are in wt%. Error bars represent 2S analytical uncertainty. 91 Figure 25. SEM images of grains showing the lines along which compositional profiles were constructed. Analyses were done at 20 \in\ intervals, except for 69WB66-F which were done at 10 um intervals. 92 Figure 25. Continued. 94 CM O V CO CM CM CN CO CO CO O O CO tM CM i- p o OCO o o V V LL 0) CM LL. CO V o o CD LCUO TO O) TO o ra "c '• ~ o 3 o TO N N O) No N N N o CO iS 2; >. >s ^ >. ^- ^ _ t co 3^3 £ •2 '5 S «> 3 .E TO TO TO TO sz 'ro 'ro 'co 'co 2 w w £ ra co CO (0 co N 2 co c a n TO ro ra l co x: bh i ra l in CO CO o X) 3 O TJ co o •J=3 Li CO to CO CD ra .C 7 c o szc 3 x3 i C e o OCOCOLOCOCOCOCOtO CO CO U> CO NI CD ro CO >. co ro CO E E § fc .2 JS O) rag, "O CO c c c c g to ro -§ JS JS co CD CO CO CO CO c SEE > o o mMi m o l o E >.>->.>, 3 to W) CO C o3 .c ' + 06 o3 + + + 08 + E CD CD CO > T3 s O o cu cu Ea . E CD E g CL £ co o CD a. > a. 8 o CO o m = 75 = CO ro ro ro c O co o O O ro ro CM c o £ o g 0 ro ^ >. Pyroxenite -0.20 0 00 0.20 0.40 -0-20 000 020 TiSi TiSi Melasyenite 1 1 1 • zm8 T zml6 - - 1 1 0.00 0 20 0*0 -020 0.00 020 0« -0« -O20 O.X 020 040 TiSi TiSi FeSiMgH4 Syenite 0.60 1 i • i * zml8 * zm27 - * zm43 0.40 - ^ zm39a * + 0.20 - * it 0.00 f f , i . i , t Q.X 020 0.40 -020 0.00 020 0.00 020 TiS TGi FeSMgB4 Figure 26. Thompson component plots for all samples from this study. For each sample, plots include exchange components TiSi- vs. TiMgFe(3+)2-; TISI- vs. AIFe3+-; and ((FeMg)-H4Si) vs. TiMgFe(3+)2-. 97 Glacier Bartnick 2 00 , .- 97BN1-4 O BN15-1 3»U • mi— fl.QG 020 FeStMgW Cliff * - - , ! 0.40 -0.20 -0.2D 0.00 0.20 0.40 0.60 FeSIMgB4 Figure 26. Continued. 98 Dykes 0 60 Cumulus 0.00 0 20 -0.40 -0.20 0.00 0.20 0.40 0.60 0.40 -0.20 FeSIMgH4 TiSi Volcanic 1 1 1 I • 69WB66-5 - - _ • • 0.00 j- i c 1,1. 0.40 .[)20 •0 20 0.00 0.20 0.40 0.40 o*o FeSiMgH4 Figure 26. Continued. 99 i , • • O Decreasing aSi02 Igneous • Crowsnest] 8 A - _ rr 0 OQ) cP — o o Decreas i o o 0 • °c ° . 1 t 0 00 0.20 -0.40 -0.20 0.40 0.GO TISI 1 i 1 ! 1 A Skarn « - - 5 - •""020 >* I ,1,1, 0.*J -0.20 0.00 020 -0.40 -0 20 0.00 0.20 040 0 60 TiSi FeSiMgW 1 1 1 1 •' 1 Decreasing aSiO, - X Dykes Q, * 040 - u **** - - £ CD ca a *~0.20 X X tt - 0.00 0.00 j-— 1 i ' , 0.00 0.20 0.40 -0.20 0.00 0.20 040 -020 0.00 0 20 0.40 0 60 •O.20 TiSi TiSi FeSiMgH4 Figure 27. Thompson component compilation plots for all igneous, skarn, and dyke samples from this study. Plots are as in Figure 26. 100 c) Skarn 0.40 Q80 120 160 2 0 040 060 120 160 2 0 040 060 120 160 2 Norm Norm Norm 0 040 080 120 160 2 0 . 040 060 120 160 2 0 040 060 120 160 2 Norm Norm Norm Figure 28. Thompson component compilation plots for all igneous, dyke, and skarn samples from this study, a, b, c plots are norm of the vector vs. H4Si-; d, e, f plots are norm of the vector vs. TiMgFe(3+)2-. 101 Other Chemical Techniques Used to Describe Titanian Andradite 5.1 Introduction To fully characterise titanian andradite, several other chemical techniques were used including wet-chemical analysis, and FTIR spectroscopy. Wet-chemical analyses were performed at McGill University, and infrared spectroscopy was done in the chemistry department at the University of British Columbia. 5.2 Wet-chemical Analyses Ten samples were analysed for FeO content by wet-chemical analysis for use in establishing site occupancies of the iron cations. Samples were chosen to represent each of the different rock types and environments of formation in this study, also X-ray diffraction was done on those samples on which duplicate analyses were performed; whereas other samples were chosen based on the amount of material available for analysis as each analysis requires at least 0.25 grams of pure powdered crystal. Analytical precision of FeO measurements was tested on five of the analysed samples through duplicate analyses (Table 6). Several of the duplicate analyses differ outside of detection limit error because of the small amount of sample available for analysis, and because of slightly inhomogeneous powders caused by small inclusions within the crystals. Figure 29 shows comparisons of duplicate analyses for the five samples. Both analyses for each sample should plot on the 1:1 line. Deviation from this line is caused by the above mentioned factors as well as by analytical discrepancies. 5.3 FTIR and Estimates of OH 5.3.1 Literature Review of OH Site Occupancy 102 Solid solution relationships exist between andradite and hydroandradite, and in such H-rich garnets, OH" likely occupies the tetrahedral sites and substitutes into the site 4 4 according to the reaction (O^) " <-»• (Si04) " (Basso et al. 1981; Rossman and Aines 1986; Lager et al. 1989, Matsyuk et al. 1998; Amthauer and Rossman 1998) which requires silica undersaturation at the tetrahedral site (Onuki et al. 1982; Lager et al. 1989; Armbruster 1995; Matsyuk et al. 1998) and charge balance is achieved by 04H4 (Lager et al. 1989). Certain authors propose that OH" substitutes into the octahedral or dodecahedral sites as a coupled substitution, such as with Fe (Amthauer and Rossman 1998; Basso et al. 1981), however Lager et al. (1989) repudiate this idea. Armbruster et al. (1998) indicate that Ti4h bearing octahedra are favourably surrounded by OH groups or by (Fe,+, Al3+) tetrahedra. These authors also state that previous authors who assigned Al to the Z site to balance the Si deficiency were unaware of the hydrogarnet substitution and were therefore in error, and all Al should be assigned to the octahedron. Peters (1965) and Armbruster et al. (1998) state that substitution of H for Si causes an increase in cell edge, a decrease in refractive index, and possibly birefringence in garnet caused by low-symmetry distribution of the OH groups (Rossman and Aines 1986). All Ti must be in the 3+ valence state and at the octahedral site to correct for the increase in cell dimensions (Basso et al. 1981; Onuki et al. 1982; Lager et al. 1989; Armbruster 1995; Armbruster et al. 1998). OH" content in titanian andradite can be up to 2.5 wt% H20, and increases with increased Ti-content (Armbruster 1995; Amthauer and Rossman 1998). The OH" content of titanian andradite from volcanic suites ranges from 0.01 to 0.04 wt% H20, whereas OH" content of skarn titanian andradite falls between the igneous and volcanic extremes (Amthauer and Rossman 1998). ' • 103 5.3.2 FTIR Methods Infrared spectroscopy is an extremely sensitive method for detecting trace amounts of water within crystal structures (Wilkins and Sabme 1973). A few parts per million water can be detected in a mineral using this technique which can produce OH stretching bands in the absorption spectrum usually between 3600-3000 cm"' (Wilkins and Sabine 1973; Rossman and Aines 1991). Pressed pellets were made for all samples from this study using 200 mg KBr mixed with 2 mg powdered, hand-picked single crystal titanian andradite. Qualitative infrared spectroscopy was done for several samples from this study by Lee Groat, however no water was detected. The samples either have no water present, or this water was insignificant enough to be masked by background noise. Table 6: Wet-chemical analyses of FeO in select garnet samples. Sample FeO (%) Fe203 (%) Total Fe as Fe203 Z951 1.66 23.24 25.09 Z951 1.78 23.11 25.09 ZM16 3.17 21.16 24.68 ZM16 3.35 20.95 24^68 ZM39B 2.16 23.65 26.05 ZM39B 2.12 23.69 26.05 BN14 1.47 . 3.28 4.91 BN14 1.19 3.57 4.91 69WB665 3.12 19.74 23.21 69WB665 3.13 19.73 23.21 ZM26 1.71 15.33 17.23 Z956 1.75 18.78 20.72 Z957 1.23 23.16 24.53 Z955 0.54 10.74 11.34 BN151 0.68 11.12 11.88 Detection limit(%): 0.01 0.01 Note: Total iron provided by microprobe analyses FeO determined using ammonium metavanadate titration 105 Figure 29. Comparison of FeO concentrations for duplicate analyses from several samples. The 1:1 line indicates identical duplicate analyses of perfectly homogeneous crystals which lack inclusions. 106 X-ray Diffraction Analysis 6.1 Introduction to Diffractometry Atoms are arranged in a periodic way in crystals. As X-rays fall on a crystal, each atom becomes the centre of a scattered wavelet which interfere with one another to produce an observable diffraction phenomena on a photographic plate placed normal to the incident beam (Guinier 1952). When X-rays of known wavelength fall on a crystal, the determination of the crystal structure is possible (Guinier 1952). To determine the whole crystal structure, it is sufficient to know the nature and positions of the atoms of one unit cell (Guinier 1952). The Bragg relationship shows how the crystal spacing can be determined by measuring the angles of diffraction if the wavelength of the X-rays is known. The Bragg relationship states "If an incident ray, of wavelength X, encounters lattice planes of spacing d at an angle 9, it gives rise to a diffracted ray in the direction of the ray reflected by the planes considered, on condition that nA,=2dsin9, where n is a whole number..." (Guinier 1952). Measurements of diffraction angles of X-rays allow us to determine only the point lattice of the crystal but to determine the arrangements of atoms within the unit cell, measurements of the intensities of diffracted beams are required (Guinier 1952). Intensity of X-rays depends on the arrangement of the atoms of the base and the relative values of the intensities are usually measured or estimated from lattice planes in the crystal (Guinier 1952). To deduce the structure of a crystal from its diffraction pattern involves determination of the reciprocal lattice, the determination of the crystal lattice, and the determination of the position of the atoms in the unit cell. X-rays provide only the 107 measurements of intensity of the diffracted beams (Guinier 1952). Either powder or single crystals may be used in X-ray diffraction, however single crystals provide a more complete analysis as the diffraction patterns are simpler (Guinier 1952). There are two methods of examining single crystals: the rotating crystal method in which a beam of monochromatic X-rays is used, and the Laue method in which polychromatic radiation is used (Guinier 1952). Polychromatic diagrams are less rich in information than are monochromatic diagrams, they do not give the absolute values of the lattice constants of the crystal, and are only easily interpreted if an important axis is coincident with the direction of incidence (Guinier 1952). In summary, single crystal diffractometry is used to determine crystal structures which includes the measurement of unit cell parameters, and the nature of the atomic arrangement. 6.2 The Andradite Unit Cell by Powder Diffraction Five samples, ZM16, ZM39B, 69WB66-5, Z95-1, and 97BN1-4, were selected for detailed X-ray work based on different rock types, different environments of formation, and different chemical compositions of andradite. The unit cell for sample 97BN1-4 could not be determined as the sample has strong and very fine chemical zoning which produces peaks which are wide and interfere with one another. Powder XRD analyses were carried out at the University of British Columbia using a Siemens D5000' diffractometer at operating conditions 40mA and 40kV, 0.04 step, 2mm divergence and antiscatter slits, 0.2mm receiving slit, and incident and diffracted beam Soller slits. Hand-picked single crystals from each of the samples were powdered for XRD analysis using a mortar and pestle. CaF2 was added (1:2) to the powdered andradite. Clean glass 108 slides were moistened with ethanol, a small amount of powder mixture was placed in the centre of the slide, and a probe was used to spread the powder evenly and in random orientation over the slide to prepare the smear mount. The resulting raw peak files contain both andradite peaks as well as CaF2 peaks, which are very well constrained and can be used to determine a correction factor based on the difference between the accepted 26 CaF2 values and the measured 26 values once Ka2 peaks have been stripped using either the EVA or PowderX programs. The correction factor found for CaF2 can then be applied to the andradite peaks for a particular sample. Usually, an average of the differences between several strong theoretical and measured peaks is adequate for use as a correction factor however, as was the case for Z95-1, if each difference is drastically different and the average does not represent the differences for the majority of the CaF2 peaks, an alternate course must be taken to determine individual correction factors for each andradite peak. For sample Z95-1, a graph was constructed (Figure 30) of the measured CaF2 26 values versus the difference between the measured and theoretical CaF2 values. A best- fit line was drawn through this data. The vertical distance from each point to the best-fit line, either positive or negative, is the correction factor for that point. A CaF2 point and its corresponding correction factor was applied to the nearest measured andradite value to produce corrected andradite values. In this case, each andradite may have a different correction factor. Once the correction factors were determined and applied to the andradite values, the program Celref2 was used to determine the actual unit cell of the andradite for each sample, as listed in Table 7. Values used in this program include: A"ctl = l .5406; 109 26,=15.000; 262=148.000; system=cubic; space group=/a3ci; CT=12.045A (for Z95-1, a=12.056A after Deer et al. 1997). A pure quartz-CaF2 mixture was done under the same conditions as the andradite to monitor the accuracy of the XRD. The quartz unit cell is known to four decimals and is highly reproducible. The results are listed in Table 7. The measured quartz values are within one significant figure and accurate to the third decimal of the accepted quartz unit cell: 6.3 Single Crystal X-Ray Diffractometry The methods used to obtain single crystal X-ray diffraction data involve several steps including crystal selection, data collection, and structure refinements. The first step in single crystal X-ray diffractometry is to crush some of the selected sample and pick six or seven grains which are placed in the air grinder. The crystal selected for analysis must be a true single crystal, round, and 0.2 mm in size. The selected crystal was mounted on the end of a glass fibre using epoxy. The fibre was mounted in a Siemens P3 automated four-circle diffractometer operated at 50 to 55 kV and 25 to 35 mA, with graphite-monochromatized MoKa radiation. After taking the photographic plate, twenty-five strong reflections distributed in more than one octant of the reciprocal lattice (Basciano 1999) were chosen and entered into the computer. The four-circle centres these reflections and calculates probable cell parameters and the orientation matrix required to collect a data set (Basciano 1999). The correct unit cell was determined using 50 high-angle reflections in the range 54 to 59 2q and least-squares refinement produced the cell dimensions for each crystal (Lam 1998). no Intensity data were collected in the 0-20 scan mode, using ninety-six steps with a scan range from [20(MoATa,)-l.l°] to .[26(MoATa,)+l.l°] and a variable scan rate between 2.0 and 29.37min depending on the intensity of an initial one second count at the centre of scan range. Backgrounds were measured for half the scan time at the beginning and end of each scan. The stability of the crystal was monitored by collecting two standard reflections after every 23 measurements. There were no significant changes in their intensities during data collection. Data was then collected for the absorption correction. One octant of reflections was collected from 3 to 60° 29. Ten to 14 strong reflections uniformly distributed with regard to 29 were measured at 5° intervals of vj; (the azimuthal angle corresponding to rotation of the crystal about its diffraction vector) from 0 to 355° (Basciano 1999). These data were then used to calculate the absorption correction, which was then applied to the entire data set. The data were also corrected for Lorentz, polarization, and background effects, averaged and reduced structure factors. Structure solution and refinement were done using the Siemens SHELXTL Version 5.03 system of programs. For structure solution the heavy atoms of the mineral were located using the Patterson method followed by inputting the lighter elements. Once a trial structure has been obtained, the refinement process can be carried out. The three fractional coordinates for each atom are refined except where the origin of the unit cell must be fixed or where an atom is situated on a symmetry element, which causes one or more of the atom coordinates to be fixed and not refined (Basciano 1999). The lowest R value was found through various steps including setting cations and possible anions anisotropic, restricting observed data to larger a(F) values, omitting individual Ill reflections, using a weighting factor, and refining atoms versus a substituting element. Once heavy atoms have been located and refined as a trial structure, a difference Fourier wall usually yield the positions of the remaining non-hydrogen atoms. Before the final refinements of the structures, the program STRUCTURE TIDY was used to standardise the atomic positions (Lam 1998). 6.4 Summary Powder XRD analysis for the volcanic sample indicates a cubic cell and a small cell volume, which eliminates the possibility of large amounts of undetected water, as water substitution increases the cell edge of the tetrahedra. ZM39B shows exactly the same cell dimensions and volume as the volcanic sample, which indicate yet more similarities between the two, aside from those determined by EPMA analysis. The melasyenite sample (ZM16) shows slightly larger cell dimensions and a larger volume. The larger volume may be indicative of OH substitution, however Virgo and Huckenholz (1974) statethat both Fe3+ - O and Ti4+ - O bond distances are larger than the Si-0 bond length and substitution of either (or both) cation(s) on the tetrahedral site accounts for the cell parameter increase and also a cell volume increase. The only skarn sample tested with powder XRD shows a volume increase which may be indicative of tetrahedral ly coordinated water. Figure 31 shows the relationship between cell volumes and chemistry. A general linear correlation exists between cell volume and amount of Ti02 (Figure 31a) as well as 3+ between cell volume and the TiMg[Fe ].2 Thompson exchange component (Figure 3If). 3+ The TiMg[Fe ].2 correlation is much stronger than the Ti02 correlation. The trend in Figure 31 f continues through Ti equal to zero, or ideal andradite. This may indicate that 112 cell volume varies with Ti02 content and that the titanium substitution mechanism may 3+ be via the TiMg[Fe ].2 exchange component for all andradite crystals. While Thompson components do not represent real mechanisms of element substitution, they may be 3+ correlated to actual mechanisms of exchange, therefore the TiMg[Fe ].2 correlation may indicate that volume is controlled by octahedrally coordinated cation exchanges and possibly that Ti substitution is controlled at this site. No correlation was evident between cell volume and H4Si, however most values for the samples examined were zero for this exchange component. 113 Figure 30. Z95-1 2 theta CaF2 correction factors. Solid line represents best-fit through the data. Vertical axis represents the difference between theoretical and measured values. The correction factor is equivalent to the vertical distance from each point to the best-fit line. Points that lie above the zero line have a positive correction whereas those below are negative. 114 to to E o L_ H— fl- CM fl- CD m jo o> fl- "fl ro h- CD uo co fl- "to N- ^ o CD 05 05 05 -fl" fl" fl" £ CM iro_ CO g CM fl" - - IT) O O O ~o O CM Csi CM CN I c fl- CD LO X> 0) 00 o> a) cn o •fl- -fl fl- CM -fl CM _C0D) O O O (0 II CN CM CN OJ Q 05 0)01 Ct CO Zr co X 31, N- T "fl -fl" CD CJ) co CN •fl CM t_ =5 O O O CD CM •o o CM CN CN «S 5 £ CD CD &l E o CJ CD O CD O CO CO CO CO CN fl" fl" CD 00 CO 00 3 CD C CO T> •fl- 0 § | J2 CD P JJ CD O CD i CN CD Li. CO CD CD _CD O _Q CD CD 00 gg co cn O N co N N 115 27 . b) i 26 • 25 O - T A 24 - • 23 i . i 1735 1740 1745 1750 1755 1760 1735 1740 1745 1750 1755 1760 Cel\dume Cell\bLime 008 1.7 i • d) i ' i 16 A T 15 - - 1.4 1.3 i , i i 1735 1740 1745 1750 1755 1760 1735 1740 1745 1750 1755 1760 Cell\rfolume CeBXAbtume 0.16 0.16 1735 1740 1745 1750 1755 1760 1735 1740 1745 1750 1755 1760 CellUAffne CelNAjlume Figure 31. Measured cell volumes for several samples from this study. Cell volumes are as in Table 7, whereas all other values are as in Table 4. Legend is as in Figure 26. a) Cell volumes vs. Ti02 wt.%; b) cell volumes vs. Fe203 wt.%; c) cell volumes vs. Fe2+ calculated formula unit; d) cell volumes vs. Fe3+ formula unit; e) cell volumes vs. TiSi- Thompson components; f) cell volumes vs. TiMgFe(3+)2-. 116 An Analysis of Site Occupancy in Titanian Andradite 7.1 Recapitulation of Andradite Crystals 2+ The general chemical formula for garnet is X3Y2(Z04)3, where A"=Ca, Mg, Fe , Mn24; 7=A1, Fe3+, Mn3+, V3+, Ti4+, Cr; and Z= Si. In titanian andradite, the Z site is silica- undersaturated which allows for substitution, or coupled substitutions, of cations, such as Ti and OH. The structure consists of alternating Z04 tetrahedra and Y06 octahedra which share corners to form the three-dimensional framework (Figure 32). The X cation is coordinated by eight oxygens and forms a third kind of polyhedron that is a distorted cube or a triangular dodecahedron. The polyhedra are distorted as the shared edges are not equal (shortened) to unshared edges because of the radius of the X ion and any substitution at theX-site will affect the whole garnet structure. 7.2 Literature Review of Site Occupancy in Titanian Andradite Titanian andradite occurs as a primary magmatic phase in the ZMP. Titanian garnets have been used to discuss the relationships between Si, Fe3+, Al, and Ti in zoned crystals. It is widely accepted (though still debated) that Ti4+ occurs mainly in the octahedral position replacing Fe3+ and that the relative preference for the tetrahedral site must be in the order Al>Fe>Ti (Huggins et al. 1977). The site occupancies of OH and Ti3+ are unresolved. Table 8 shows the most widely accepted cation site substitutions for titanian andradite. Isaacs (1968) states that the principle exchange mechanism in andradite is Ti4+ replacing Fe and that no relation of Si with Ti nor Fe is evident. Isaacs (1968) also hypothesizes the possibility of Ti substituting in valence states other than, or in addition 117 to, four but suggests that they would likely appear in chemical analyses as four only. It was previously believed that Ti directly substituted for Si, but Si is not the only element being replaced by Ti, as the cation imbalance caused by declining Si is better matched by Fe31 at this site than by Ti4+ (Howie and Woolley 1968) or by combined Fe3+ and Fe2t (Armbruster et al. 1998). Whether Ti4+ or Fe3+ substitute at the tetrahedral site, the similarity of the bond distances Fe3+ -O and Ti4+ -O, both of which are larger than the Si-0 bond length, will produce an increase of the cell parameter and the cell volume (Virgo and Huckenholz 1974). Substitution of Si occurs in decreasing preference by Al, Fe3+, and Ti4+ (Hartman 1969; Huggins et al. 1977a); however at high temperatures, the tetrahedral site preference is argued by Schwartz et al. (1980) to be Fe3+ >A1 >Ti4+. Hartman (1969) shows that Ti4+ takes on preferentially octahedral coordination and Fe3+ takes on tetrahedral coordination. The role of Ti4+ has been debated since 1969 by various authors. Manning and Harris (1970) state that Ti4'1" prefers the tetrahedral Si sites which was later confirmed by Weber et al. (1975b), Huggins et al. (1976b), Huggins et al. (1977b), Kuhberger et al. (1989), Dingwell and Brearley (1985). Some authors maintain that Ti4+ substitutes at the octahedral site, thereby displacing Fe3+ and Al3+ to the tetrahedral site (Moore and White 1971; Dowry 1971; Weber at el. 1975a; Amthauer et al. 1977; Gongbao and Baolei 1986; Peterson et al. 1995; Locock et al. 1995) whereas others state that Ti4+ can be either tetrahedrally or octahedrally coordinated (Armbruster et al. 1998; Waychunas 1987; Tarte et al. 1979; Huggins et al. 1976b) with Al preferring octahedral coordination (Armbruster et al. 1998). Yet another school of thought calls for the existence of Ti3+ (Isaacs 1968; Dowty 1971; Huggins et al. 1976b; Amthauer et al. . 118 1977; Gongbao and Baolei 1986; Kuhberger etal. 1989; Locock et al. 1995; Malitesta et al. 1995, Armbruster et al. 1998) which substitutes exclusively at the octahedral sites (Manning and Harris 1970; Dowty and Clark 1973; Basso et al. 1981; Onuki etal. 1982; Dingwell and Brearley 1985; Waychunas 1987; Kuhberger et al. 1989; de Groot et al. 1992; Locock et al. 1995; Malitesta et al. 1995; Merli et al. 1995) or, alternatively, substitutes exclusively at the tetrahedral site (Huggins et al. 1975). Huckenholz et al. (1976) state that natural garnet samples are characterised by Si+Ti > 3.0 per formula unit and therefore it is necessary to consider part of the iron and titanium as Fe2+ and Ti3+, respectively. As Ti is always in excess relative to the calculated Si deficiencies, the presence of other cations is necessary to ensure that charge is balanced. Huggins et al. (1976b) neither confirm nor deny the existence of Ti3+ in andradite but state that it can not be distinguished from Fe2+. 7.3 Results and Ideas from This Study Though some of the experimental attempts herein to solve or further our understanding of titanian andradite site occupancies have proved unsuccessful, some conclusions and interpretations can be made. Microprobe analysis and the resulting calculated atoms per formula unit show, for the most part, that all of the Ca2+must be assigned to the X site and that this site is then approximately 2.9/3.0 full. Na+ and Mn2+, usually combined, add up to fill any vacancies on the X site. Mn2+ substitution at the X site would not cause structural distortions. If the X site is filled with both Ca2f and Na+, then the remaining Mn2+ must be assigned to the Y site. The presence of both valences of Fe is confirmed by wet-chemical analyses. Al34 and Mg*+ must be assigned to the 7 site, as is any excess Mn. Fe2+, Cr, V, Ti4+ are also 119 assigned to this site. Most Fe3* can also be assigned to this site, with generally 0.1 ions over the 2.0 Y site total, which are then assigned to the Z site. However, with regards to the assignment of Fe3+ and Ti4+, it is their combined total that requires some reassignment to the Z site, but it is unclear whether the excess is made up of only one, or a combination of the cations. Cell volume, as determined by powder XRD analyses, varies 3+ with Ti02 content and the titanium substitution mechanism may be via the TiMg[Fe ].2 exchange component and in octahedral coordination, as opposed to substitution via the TiSi- component and tetrahedral coordination. Therefore Ti4+ is assigned to the octahedral site. The author has assigned any excess on the Y site as Fe3+, but with acknowledgment that the excess may well be caused by Ti4+ or by a combination of these cations. Totals for these cation site assignments are shown in Table 9. With excess Fe3", all Si, Zr and calculated H assigned to the Z site, most totals are only slightly below 3.0, which may be accounted for by a slight underestimation of the totals for either the iron or titanium valence, or by underestimation of the total water content. The exceptions to this cation assignment are sample BN1-4 and the volcanic sample which are both over 3.0 total for the Z site, at 3.06 and 3.09, respectively. The volcanic sample total can be explained because of the higher than average total iron (wt%), thereby some of the iron is likely in the wrong valence, which is evident in the Y site total 2.25/2.0. XRD analysis for the volcanic sample indicates a cubic cell and a small cell volume, which eliminates the possibility of large amounts of undetected water, as water substitution increases the size of the tetrahedra. As either Ti4+ or Fe3+ substitute on the tetrahedral site, the cations will produce an increase of the cell parameter and the cell volume (Virgo and Huckenholz 1974), therefore most of the iron 120 is likely in the 2+ valence state, and all of the f i is in octahedral coordination. The BN1-4 Fsite total is slightly elevated at 2.09/2.0, however the main cause of the high cation site totals lies with the Z site. Although none of the samples tested in the 1R trials showed appreciable OH, the presence of anisotropy in this sample is indicative of either large amounts of undetectable OH, or cation ordering of Fe31 and Al at the octahedral sites. Cation ordering explains the elevated Y site total as there may be more Fe3+ on this site than is allotted, which brings the Z site total down slightly. A lower Z site cation total could accommodate the larger amounts of water necessary to produce anisotropy. Natural garnet become more and more silicon-deficient with increasing f02 (Huckenholz et al. 1976) as is the case with BNl-4, thereby making even more room on the Z site for water substitution. No cell volume is available for this sample, however the skarn sample tested with powder XRD showed a slight volume increase which may be indicative of Z site water: Future Work Future work still to be performed on titanian andradite includes solving the site occupancies of cations on the Y and Z sites, as well as determining the valence(s) of titanium. The most likely way to solve for Ti valence is with the use of X-ray absorption spectra (de Groot et al. 1992). The presence of total water in natural titanian andradite. could be determined using either single crystal X-ray diffraction given the appropriate time scales, or thermogravimetric analysis in which the sample is heated on a balance and the resulting weight loss is equivalent to the amount of water driven off. Electrolytic water determination has also been used to quantitatively measure the water content of silicates (Wilkins and Sabine 1973). Once the presence and amount of water can be 12.1 established, the site occupancy then needs to be determined, most likely by the use of single crystal diffraction or of Mossbauer spectroscopy (Gongbao and Baolei 1986). Figure 32. Portion of the garnet structure projected down the c-axis (after Schwartz et al. 1980). Note the framework of alternating corner-shared Y06 octahedra and Z04 tetrahedra, and the chains of alternating edge-shared X08 dodecahedra and Z04 tetrahedra. Table 8: Widely accepted cation site occupancies. dodecahedral octahedral tetrahedral cation Xsite Ysite Z site Refetence Si4+ 1* e.g.-Basso et al. 1981 Ti4+ 2* 2 Armbruster et al. 1998 Ti3+ 1 cannot eg. Basso et al. 1981 Zr4+ 2 Deer, Howie, Zussman 1997 AI3+ 1 cannot Armbruster et al. 1998 1 Huggins et al. 1977 Cr3+ 2 Deer, Howie, Zussman 1997 V3+ 1 Locock et al. 1995 Fe3+ cannot 2 2 Armbruster et al. 1998 Fe2+ cannot 2 2 Armbruster et al. 1998 Mn2+ 2 2 Locock etal. 1995 Mg2+ cannot 1 Lager etal. 1989, Labotka 1995 Ca2+ 1 Armbruster et al. 1998 Na+ 1 Locock et al. 1995 H+ 3* 3 1 Amthauer + Rossman 1998 1 * = element must go on this site 2* = element sometimes goes on this site 3* = element could possibly go on this site 124 co CO i- |v- O CD CO CN T— COC D CN CO o o CN -r- 00 CO co T- O CM o CM co O CD O CD O O O CD O o o CO CO T— T— c\i oo odd O O CD d ci ci CN d d CO CO co d d i- CN d d d T- 00 CD o O CJ) O xj- O CM CN O CO t- LO •M- r-~ CO co co o o O O h- o o o co O CO o o o co o o CcNn Oo Oo TO- O O O O O CN oO oO co T- co od d CN d N CO o> O COOT-K-O-t-T-OOCNh-T-CM o CO o co o CSI COT-OCNOON-OT-OCOOO o cr> o cn oo o o o CMdddddT-^dddcN'dd co ^ cd CN d CO CO T- T- d T- CM d Oi O -cooLOLOLnT 00 ocNi-cooT -LO OO N CD o> LO LO LO oqcNO^roo^rooocnoo o co o o o o CN dddddT-'dddcNod cd d •sr CD T- r- cd -r-^ ro CN O CO N CO Oj O ^rCDT-O CDT-OOOCN^rcOCN o o CD o CO o o o in ^ ^ o cqcNOcoooLoooocnoo n T- r- co d N CO CN d d d d d -c^ d d d CMid d od CN O N co O) O CO v-cooLno-r-ooT-'^-i-h-'M*' CD CD 00 cr> T- CN CO LO LO oocooooocooooooo cn T- CO T- o o T- cn cNddddd-r-dddcddd o o cd d d T d N co T— co - OJ CN CO O) O CNCOOT-OO^TOT-CDCDOO LO LO CD r- O cn cocNocooooooocnoo CD O o r>- r- cn CN O O O O O o co o CN d CO CN T- O O O CN O O co co CN o CN d Q- ^ CMI-T- CT T T- )i— -^J-i—r-CDOrOO co LO o T CO LO co coC D co ^) T- h- i- O O CN 00 T- T- CDCOOT-OOIDOOOOOO cn co T— cd cd d d T— CN d CD 4 cNdddddt-'dddcddd CN ? 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This thesis has contributed three things to further the understanding of titanian andradite. Firstly, chemical compositions of titanian andradite were determined for the different environments of formation. Secondly, chemical zonation patterns unique to different environments of formation were . established. Thirdly, the crystal chemistry of titanian andradite was examined, specifically the role and substitution mechanism of Ti and, to a lesser extent, the role of OH on the crystal chemistry. The results from the various tests performed on the whole- rock samples from this study are summarised below and these results are applied to a petrogenesis for the sample suite. Geochemical results indicate that pyroxenite samples have undergone fractionation as evidenced by FeO enrichment, and sample ZM39B contains fewer incompatible trace elements than do other samples, indicative of an early formation. Of petrographical significance is sample 97BN1-4, which is the only sample from this study that has anisotropic zones, twinning, and visible regular zoning in the titanian andradite. Chemical zoning is visible using BSE imaging. Magmatic titanian andradite samples show irregular zoning, the volcanic sample has irregularly zoned cores and regularly zoned rims, as does ZM39B. Titanian andradite from magmatic dykes shows 127 both regular and irregular zoning, skarns show only irregular zoning, with the exception of 97BN1 -4 which is very regularly zoned but contains irregular zones inside of the regular zones. EPMA data from titanian andradite reveals zoning patterns within different rock types and between different environments of formation. Both the volcanic and cumulus samples have the same patterns, including: darker zones which have more Ti02 and A1203 and less Fe203 than lighter zones; A1203 and CaO have the same zoning pattern, opposite to that shared by Ti02 and Fe203; and the change in Ti02 is the same or twice that of Fe203. In the syenite samples, A1203 changes by half that of Ti02, whereas the melasyenite samples show that Ti02 change equal the changes of Fe203, and generally shows either no zoning or irregular zoning. The pyroxenite samples show regular zoning with darker zones which have more Al203 and less Fe203 than lighter areas, as well as equal and opposite changes in Ti02 and Fe203. The magmatic dykes show regular or irregular zoning in which the darker areas contain more A1203 than lighter areas. Cliff samples share many characteristics with the early-formed magmatic samples, whereas other skarn samples are similar to later magmatic stages and show the absence of zoning and have darker areas which contain more A1203. Thompson components provide definite ways to distinguish between titanian andradite formed in different environments. Magmatic samples have small norms, negative MgCa-, very small H4Si component, and positive FeMg-, whereas hydrothermal samples predominantly have positive H4Si, zero to slightly positive FeMg-, and larger norms. Magmatic dykes have been infiltrated by an externally derived fluid as they have zero or slightly positive FeMg- components, and many large H4Si values. Cliff and other 128 3+ skarn samples have near equal average amounts of both TiSi- andTiMg[Fe ].2 components, small norms, and are therefore intermediate between magmatic and hydrothermal samples, in terms of fluid evolution. 97BN1-4 has the largest norm and is, furthest in composition from a true andradite. Five different titanian andradite types identified on the basis of zoning and Thompson components are as follows: magmatic "A" or primary magmatic samples which include ZM39B and WB66-5; magmatic "B" which include most of the magmatic samples (e.g. ZM16); skarn "A" which can be further subdivided into two groups including Cliff samples which show a magmatic affinity in chemical zoning, and most other skarn samples excluding BN1-4; skarn "B" consists of only the hydrothermal sample BN1-4; and dyke samples which have a magmatic signature overprinted by skarn "A" fluids. Titanian andradite site occupancies as determined from the study samples are as follows: Ca2+ and Na+ are always assigned to the X site; Mn2+ is preferentially in dodecahedral coordination, but may also be in octahedral coordination; Al3+, Mg24, Cr3+, V3t, Ti4+, and Fe2" are always in octahedral coordination; Fe3+ may be either octahedrally or tetrahedrally coordinated; and Si4+, Zr4", and H4+ are always in tetrahedral coordination. Cell volume varies with Ti02 content and the titanium substitution 3+ mechanism may be via the TiMg[Fe ].2 exchange component, indicative of octahedral Ti substitution and octahedrally controlled cell volume. The petrogenesis of the Zippa sample suite is as follows, based on the data collected from titanian andradite in this study. The volcanic and cumulus ZM39B samples were the earliest to form based on euhedral, resorbed grains, identical zoning 129 3+ patterns, and low f02 and aSl02 values which are correlated by the TiMg[Fe ].2 and TiSi components, respectively. The magmatic samples formed next and fractionated by sorting from syenite through pyroxenite, and EPMA data indicate substitution and replacement between Ti02, Fe203, and A1203. One of the pyroxenite samples may have originated from a liquid, as opposed to other magmatic samples which originated from a crystal mush. The pluton evolved to a higher fQ2 state in conjunction with the evolution of a fluid phase. LowfQ2 values for titanian andradite are indicative of crystallisation at high pressure, however H2 diffusion and sulphur loss are two mechanisms which can result in pressure, and consequently/^,, changes (Virgo et al. 1976b). Cliff samples interacted with early fluids driven off the pluton and inherited the/Q2 signature from the magmatic fluid, and share many zoning and TCS properties with magmatic samples. However the Cliff samples also have an increased c3si02 as a result of cooling of the magmatic volatiles and interaction of the fluid with quartzite. Glacier and BN15-1 have all the characteristics of true skarn samples and likely formed after Cliff and before 97BN1-4, the fluids of which migrated back into the pluton probably along dykes which bear TCS evidence of interaction with both the original magmatic fluid and with slightly more evolved skarn fluids. 97BN1-4 was likely the last to fornix based on petrographic evidence, and crystallised from a more evolved fluid, as it has the largest crystals with the most complex zoning patterns, is the furthest in composition from true andradite, shows higher fQ2 and aSi02 than the magmatic or skarn samples based on TCS evidence, and has fine zones with well defined edges, indicative of long-lived interaction with a continuously or abruptly changing fluid. 130 References Akizuki, Mizuhiko. 1984. Origin of optical variations in grossular-andradite garnet. American Mineralogist, 69, pp. 328-338. Akizuki, M., Nakai, H., and Suzuki, T. 1984. Origin of iridescence in grandite garnet. American Mineralogist, 69, pp. 896-901. Allen, F.M., and Buseck, P.R. 1988. XRD, FTIR, and TEM studies of optically anisotropic grossular garnets. American Mineralogist, 73, pp. 568-584. Amthauer, G., and Rossman, G.R. 1998. The hydrous component in andradite garnet. American Mineralogist, 83, pp. 835-840. Amthauer, G., Annersten, H., and Hafner, S.S. 1977. The Mossbauer spectrum of 57Fe in titanium-bearing andradites. Physics and Chemistry of Minerals, 1, pp. 399-413. Armbruster, T. 1995. Structure refinement of hydrous andradite, Ca3Fe, 54M%20Al026(SiO4)165(04H4), ,5, from the Wessels mine, Kalahari manganese field, South Africa. European Journal of Mineralogy, 7, pp. 1221- 1225. Armbruster, T., Birrer, J., Libowitzky, E., and Beran, A. 1998. Crystal chemistry of Ti- bearing andradites. European Journal of Mineralogy, 10, pp. 907-921. Badar, M.A. and Akizuki, M. 1997. Iridescent andradite garnet from the Sierra Madre Mountains, Sonora, Mexico. Neus Jahrb. Mineral. Monatsh., 12, pp. 529-539. Bascianno, Laurel. 1999. Personal communication. Basso, R., Giusta, A.D., and Zefiro, L. 1981. A crystal chemical study of a Ti-containing hydrogarnet. Neus Jahrb. Mineral. Monatsh., 5, pp. 230-236. Chase, A.B., and Lefever, R.A. 1960. Birefringence of synthetic garnets. American Mineralogist, 45, pp. 1126-1129. Coulson, I.A., Russell, J.K., and Dipple, G.M. 1999. Origins of the Zippa Mountain Pluton: a Late Triassic, arc-derived, ultrapotassic magma from the Canadian Cordillera. Canadian Journal of Earth Sciences, 36:9, pp. 1415-1434. Cygan, R.T. and Lasaga, A.C. 1982. Crystal growth and the formation of chemical zoning in garnets. Contributions to Mineralogy and Petrology, 79, pp. 187-200. 131 Deer, W.A., Howie, R.A., andZussman, J. 1997. Rock-forming Minerals, Vol. 1A Orthosilicates. The Geological Society, London. de Groot. F.M., Figueiredo, M.O., Basto, M.J., Abbate, M., Petersen, H, and Fuggle, J.C. 1992. 2p X-ray absorption of titanium in minerals. Physics and Chemistry of Minerals, 19, pp. 140-147. Dingwell, D.B., and Brearley, M. 1985. Mineral chemistry of igneous melanite garnets from analcite-bearing volcanic rocks, Alberta, Canada. Contributions to Mineralogy and Petrology, 90, pp. 29-35. Dowty, E. 1971. Crystal Chemistry of titanian and zirconian garnet: 1. Review and spectral studies. American Mineralogist, 56, pp. 1983-2009. Dowty, E. and Clark, JR. 1973. Crystal structure refinement and optical properties of a Ti3+ fassaite from the Allende meteorite. American Mineralogist, 58, pp. 230-242. Gali, S. 1983. Grandite garnet structures in connection with the growth mechanism. Z. Kristallogr., 163, pp. 43-52. Gomes, C. B. 1969. Electron microprobe analysis of zoned melanites. American Mineralogist, 54, pp. 1654-1661. Gongbao, W., and Baolei, M. 1986. The crystal chemistry and Mossbauer study of schorlomite. Physics and Chemistry of Minerals, 13, pp. 198-205. Guinier, Andre. 1952. X-ray crystallographic technology. Hilger and Watts Ltd., London. Pp. 330. Hartman, P. 1969. Can Ti4+ replace Si4+ in silicates? Mineralogical Magazine, 37:287, pp.366-369. Hatch, DM. and Griffin, D.T. 1989. Phase transitions in the grandite garnets. American Mineralogist, 74, pp. 151-159. Henmi, C, Kusachi, I., Henmi, K. 1995. Morimotoite, Ca3TiFe2+Si3012, a new titanian garnet from Fuka, Okayama Prefecture, Japan. Mineralogical Magazine, 59, pp. 115-120. Hickmott, D.D., and Shimizu, N. 1990. Trace element zoning in garnet from the Kwoiek Area, British Columbia: disequilibrium partitioning during garnet growth? Contributions to Mineralogy and Petrology, 104, pp. 619-630. Hirai, H, Sueno, S., Nakazawa, H. 1982. A lamellar texture with chemical contrast in grandite garnet from Nevada. American Mineralogist, 67, pp. 1242-1247. 132 Holten, T., Jamtveit, B., Meakin, P., Cortini, lyfc, Blundy, J., and Austrheim, H. 1997. Statistical characteristics and origin of oscillatory zoning in crystals. American Mineralogist, 82, pp. 596-606. Howie, R.A. and Woolley, AR. 1968. The role of titanium and the effect of Ti02 on the cell-size, refractive index, and specific gravity in the andradite-melanite- schorlomite series. Mineralogical Magazine, 36:282, pp. 775-790. Huckenholz, H., Holzl, E., Huggins, F.E., and Virgo, D. 1976. A reconnaissance study of the Ti-garnet stability field at defined oxygen fugacities. Carnegie Institution of Washington Yearbook, 75, pp. 711-720. Huggins, F.E., Virgo, D., Holzl, E., and Huckenholz, H.G. 1975. Distribution of Al, Fe3', and Ti4+ between the octahedral and tetrahedral sites in garnets between Ca3Al2Si3012 and Ca3Fe2Ti, 416Si1.584012. Carnegie Institution of Washington Yearbook, 74, pp. 579-585. Huggins, F.E., Rosenhauer, M., and Virgo, D. 1976a. The intrinsic oxygen fugacities and the oxidation states of iron and titanium in natural melanite and schorlomite garnets. Eos, Transactions, American Geophysical Union, 57:4, p. 339. Huggins, F.E., Virgo, D., and Huckenholz, H.G. 1976b. The crystal chemistry of melanites and schorlomites. Carnegie Institution of Washington Yearbook, 75, pp. 705-711. Huggins, F.E., Virgo, D., and Huckenholz, G. 1977a. Titanium-containing silicate garnets. I. The distribution of Al, Fe3+, and Ti4+ between octahedral and tetrahedral sites. American Mineralogist, 62, pp. 475-490. Huggins, F.E., Virgo, D., and Huckenholz, G. 1977b. Titanium-containing silicate garnets. II. The crystal chemistry of melanites and schorlomites. American Mineralogist, 62, pp. 646-665: Isaacs, T. 1968. Titanium substitutions in andradites. Chemical Geology, 3, pp. 219-222. Ivanova, T.I., Shtukenberg, AG., Punin, Y.O., Frank-Kamenetskaya, O.V., and Sokolov, P.B. 1998. On the complex zonality in grandite garnets and implications. Mineralogical Magazine, 62(6), pp. 857-868. Jamtveit, Bjorn. 1991. Oscillatory zonation patterns in hydrothermal grossular-andradite garnet: nonlinear dynamics in regions of immiscibility. American Mineralogist, 76, pp. 1319-1327. Jamtveit, Bjorn. 1999, In Press. Crystal growth and intracrystalline zonation patterns in hydrothermal environments. In Growth, dissolution and pattern formation in geo- 133 systems. B. Jamtveit and P. Meahin (eds.), Kluwer Academic Publ., Holland. Jamtveit, B., and Hervig, R.L. 1994. Constraints on transport and kinetics in hydrothermal systems from zoned garnet crystals. Science, 263, pp. 505-508. Jamtveit, B., Wogelius, R.A., and Fraser, D.G. 1993. Zonation patterns of skarn garnets: records of hydrothermal system evolution. Geology, 21, pp. 113-116. Jamtveit, B., Ragnarsdottir, K.V., and Wood, B.J. 1995. On the origin of zoned grossular- andradite garnets in hydrothermal systems. European Journal of Mineralogy, 7, pp. 1399-1410. Jaworski, B.J. and Dipple, G.M. 1996. Zippa Mountain wollastonite skarns, Iskut River map area. Geological Fieldwork 1995, Paper 1996-1. Keep, M. and Russell, J.K. 1992. Mesozoic alkaline rocks of the Averill plutonic complex. Canadian Journal of Earth Sciences, 29, pp. 2508-2520. Kerr, A. 1981. Zoning in garnets from the mainland Lewisian. Mineralogical Magazine, 44, pp. 191-194. Kingma, K.J., and Downs, J.W. 1989. Crystal structure analysis of a birefringent andradite. American Mineralogist, 74, pp. 1307-1316. Kuhberger, A., Fehr, T., Huckenholz, H.G., and Amthauer, G. 1989. Crystal chemistry of a natural schorlomite and Ti-andradites synthesized at different oxygen fugacities. Physics and Chemistry of Minerals, 16, pp. 734-740. Labotka, Theodore C. 1995. Evidence for immiscibility in Ti-rich garnet in a calc-silicate hornfels from northeastern Minnesota. American Mineralogist, 80, pp. 1026- 1030. Lager, G.A., Armbruster, T., Rotella, F.J'., and Rossman, G.R. 1989. OH substitution in garnets: X-ray and neutron diffraction, infrared, and geometric-modeiing studies. American Mineralogist, 74, pp. 840-851. Lam, Anita Eva. 1998. An X-ray crystallographic study of the crystal structures of four tellurium oxysalt minerals: Dugganite, Choloalite, Rodalquilarite, and Graemite. Unpublished M.Sc. thesis, University of British Columbia. Lang, J.R., Lueck, B., Mortensen, J.K., Russell, J.K., Stanley, C.R., and Thompson, J.F.H. 1995. Triassic - Jurassic silica-undersaturated and silica-saturated alkalic intrusions in the Cordillera of British Columbia: implications for arc magmatism. Geology, 23:5, pp. 451-454. 134 Lessing, P. and Standish, R.P. 1973. Zoned garnet from Crested Butte, Colorado. American Mineralogist, 58, pp. 840-842. Locock, A., Luth, R.W., Cavell, R.G., Smith, D.G.W., Duke, M.J.M. 1995. Spectroscopy of the cation distribution in the schorlomite species of garnet. American Mineralogist, 80, pp. 27-38. Lueck, B.A. and Russell, J.K. 1994. Geology and origins of the Zippa Mountain igneous complex with emphasis on the Zippa Mountain pluton, northern British Columbia. In Current Research 1994-A, Geological Survey of Canada, pp. 77-85. Malitesta, C, Losito, I., Scordari, F., and Schingaro, E. 1995. XPS investigation of titanium in melanites from Monte Vulture (Italy). European Journal of Mineralogy, 7, pp. 847-858. Manning, P.G., and Harris, D.C. 1970. Optical-absorption and electron-microprobe studies of some high-Ti andradites. Canadian Mineralogist, 10, pp. 260-271. Matsyuk, S.S., Langer, K., and Hosch, A. 1998. Hydroxyl defects in garnets from mantle xenoliths in kimberlites of the Siberian platform. Contributions to Mineralogy and Petrology, 132, pp. 163-179. Matsyuk, S.S., Langer, K., and Hosch, A. 1998. Erratum to: Hydroxyl defects in garnets from mantle xenoliths in kimberlites of the Siberian platform. Contributions to Mineralogy and Petrology, 133, p. 418. Merli, M., Callegari, A., Cannillo, E., Caucia, F., Leona, M., Oberti, R., and Ungaretti, L. 1995. Crystal-chemical complexity in natural garnets: structural constraints on chemical variability. European Journal of Mineralogy, 7, pp. 1239-1249. Moore, R.K. and White, W.B. 1971. Intervalence electron transfer effects in the spectra of the melanite garnets. American Mineralogist, 56, pp. 826-840. Murad, E. 1976. Zoned, birefringent garnets from Thera Island, Santorini Group (Aegean Sea). Mineralogical Magazine, 40, pp. 715-719. Nakano, T. and Ishikawa, Y. 1997. Chemical zoning of pegmatite garnets from the Ishikawa and Yamanoo areas, northeastern Japan. Geochemical Journal, 31, pp. 105-118. Nakano, T., Takahara, H., andNishida, N. 1989. Intracrystalline distribution of major elements in zoned garnet from skarn in the Chichibu Mine, Central Japan: illustration by color-coded maps. Canadian Mineralogist, 27, pp. 499-507. Neill, I., and Russell, J.K. 1993. Mineralogy and chemistry of the Rugged Mountain 135 pluton: a melanite-bearing intrusion. /^Geological fieldwork 1992, Grant, B. and Newell, J. (eds.), British Columbia Ministry of Energy, Mines, and Petroleum Resources Paper 1993-1, pp. 149-157. Novak, G.A. and Gibbs, G.V. 1971. The crystal chemistry of the silicate garnets. American Mineralogist, 56, pp. 791 -825. Onuki, H., Akasaka, M., Yoshida, T., and Nedachi, M. 1982. Ti-rich hydroandradites from the Sanbagawa metamorphic rocks of the Shibukawa area, Central Japan. Contributions to Mineralogy and Petrology, 80, pp. 183-188. Peters, T.J. 1965. A water-bearing andradite from the Totalp serpentine. American Mineralogist, 50, pp. 1482-1486. Peterson, R.C, Locock, A.J., and Luth, R.W. 1995. Positional disorder of oxygen in garnet: the crystal-structure refinement of schorlomite. The Canadian Mineralogist, 33, pp. 627-631. Rossman, G.R. and Aines, R.D. 1986. Spectroscopy of a birefringent grossular from Asbestos, Quebec, Canada. American Mineralogist, 71, pp. 779-780. Rossman, G.R. and Aines, R.D. 1991. The hydrous components in garnets: Grossular- hydrogrossular. American Mineralogist, 76, pp. 1153-1164. Russell, J.K., Dipple, G.M., Lang, J.R., and Lueck, B. 1999. Major element discrimination of titanian andradite from magmatic and hydrothermal environments: An example from the Canadian Cordillera. European Journal of Mineralogy, 11:6, pp. 919-935. Schwartz, K.B., Nolet, D.A., and Burns, R.G. 1980. Mossbauer spectroscopy and crystal chemistry of natural Fe - Ti garnets. American Mineralogist, 65, pp. 142-153. Shore, M and Fowler, AD. 1996. Oscillatory zoning in minerals: a common phenomenon. The Canadian Mineralogist, 34, pp. 1111-1126. Smith, D. and Boyd, F.R. 1992. Compositional zonation in garnets in peridotite xenoliths. Contributions to Mineralogy and Petrology, 112, pp. 134-147. Tarte, P., Cahay, R., and Garcia, A. 1979 Infrared spectrum and structural role of titanium in synthetic Ti-garnets. Physics and Chemistry of Minerals, 4, pp. 55-63. Virgo, D. and Huckenholz, H.G. 1974. Physical properties of synthetic titanium-bearing grandite garnets. Carnegie Institution of Washington Yearbook, 73, pp. 426-433. Virgo, D., Rosenhauer, M., and Huggins, F.E. 1976a. Intrinsic oxygen fugacities of 136 natural melanites and schorlomites and ^crystal-chemical implications. Carnegie Institution of Washington Yearbook, 75, pp. 720-730. Virgo, D., Huggins, F.E., and Rosenhauer, M. 1976b. Petrologic implications of intrinsic oxygen fugacity measurements on titanium-containing silicate garnets. Carnegie Institution of Washington Yearbook, 75, pp. 730-735. Vlasova, D.K., Podlesskiy, K.V., Kudrya, P.F., Boronikhin, V.A., and Muravitskaya, G.N. 1985. Zoning in garnets from skarn deposits. International Geology Review, 27:4, pp. 465-482. Waychunas, G.A. 1987. Synchrotron radiation XANES spectroscopy of Ti in minerals: Effects of Ti bonding distances, Ti valence, and site geometry on absorption edge structure. American Mineralogist, 72, pp. 89-101. Weber, H.P., Virgo, D., and Huggins, F.E. 1975a. The role of titanium in the crystal chemistry of synthetic melanites and schorlomites. Eos, Transactions, American Geophysical Union, 56:6, p. 462. Weber, H.P., Virgo, D., Huggins, F.E. 1975b. A neutron-diffraction and "Fe Mossbauer study of a synthetic Ti-rich garnet. Carnegie Institution of Washington Yearbook, 74, pp. 575-579. Westphal, M., Jaworski, B., Dipple, G.M., and Bingemer, A. 1999, In Press. The Isk wollastonite deposits of Northwestern British Columbia. In: Industrial Minerals in Canada, CTM special volume. Wilkins, R.W.T. and Sabine, W. 1973. Water content of some nominally anhydrous silicates. American Mineralogist, 58, pp. 508-516. 137 Appendix A: EPMA Error Treatment Electron microprobe analyses of titanian andradite were carried out as described in Chapter 4. Spectrometer configurations for elemental analysis were as follows: spectrometer one (crystal LIF) analysed for Fe, Mn, Cr, spectrometer two (crystal TAP) analysed for Mg, Al; spectrometer three (crystal PET) analysed for Ca, Ti, Zr, V; and spectrometer four (crystal TAP) analysed for Si, Na, Zr. Calibration standards for the different elements were as follows: albite standard S430 forNa, diopside standard S439 for Mg, grossular standard S007 for Al and Ca, almandine standard S467 for Si and Fe, rutile standard S442 for Ti, vanadium metal standard S309 for V, chromite standard S382 standard for Cr, rhodonite standard S459 for Mn, and zircon standard S387 for Zr. The rutile, grossular, and almandine standards were analysed on the same spot on each crystal at the beginning and end of each data collection sequence as shown in Table Al to monitor any changes caused by mechanical error within the probe during a collection run. Any changes in the collection values on the calibration crystals were also monitored from day to day as a check for proper calibration and crystal setup before running unknowns, as the Ix/Istd should ideally always be 1.000. Three experiments were run on an andradite non-calibration standard (SO 17) (Novak and Gibbs 1971). The published formula of this crystal is [{Caj^MgoojMnoo^tFe, 99Al00]](Si3)O,2] (Novak and Gibbs 1971) and the recalculated composition is outlined in Table A2. First, the non-calibration standard analyses were recorded through time from which analytical uncertainty was determined. Second, a grid on and around the area analysed on the non-calibration standard was analysed to 138 determine whether the grain itself was zoned. Third, the same five points were analysed at the beginning, middle, and end of each collection sequence to show any machine variation within a collection sequence and over time. In the first experiment, the andradite non-calibration standard was used to monitor reproducibilty of the machine from day to day, from which analytical uncertainty was estimated. An example of the analyses of the andradite non-calibration standard are shown in Table A3 (see cd-rom in Appendix C for complete table). All analyses are plotted against time in Figure Al which show minor, random fluctuations about the mean. The first fifty one points show larger fluctuations about the mean as they were not analysed on exactly the same part of the crystal as the remaining analyses so were not used to describe analytical uncertainty, as described below. Second, a grid on the non-calibration standard was used to determine whether the grain itself was zoned. The non-calibration andradite was analysed over a small area in this study (Figure A2) and was found to be weakly zoned with respect to Ca, Al, Fe, and Si (Figure A3, Table A4. See cd-rom in Appendix C for complete table). Therefore no direct comparison can be made between the reported Novak and Gibbs (1971) results and those listed herein without knowledge of the exact location of their analyses on a zoned crystal. Third, machine variation within a collection sequence and over time was determined. After the first fifty one analyses, five points in row three of Figure A2 were each analysed at the beginning, middle, and end of each run (Table A5) to establish consistency of analytical technique, as well as to establish the exact analytical uncertainty as shown in Table A6. The first 51 points analysed on the andradite standard 139 were not included in the calculation of the analytical uncertainty as these points were not on exactly the same five points analysed the remainder of the time, and therefore would contribute sample variance to the probe machine variance because of the weakly zoned nature of the crystal. Plots of oxides for each of the five repeatedly analysed points are shown in Figures A4-A8 which show that almost all apparent variations in elemental percentages are within analytical uncertainty and are therefore random. The large 26 values associated with A1203 and Fe203 (approximately ± 1 wt.%) are possibly a result of compositional variations in the non-calibration standard at a scale smaller than the probe beam size, and therefore these calculated 2 thetas may contribute sample variance to the probe machine variance. Ideally, the values listed by Novak and Gibbs (1971) should correspond to those analysed in this study, however this study analysed and re-analysed only a small part of the crystal whereas Novak and Gibbs (1971) do not describe the location, the number of analyses done, nor their analytical conditions or setup procedures, therefore no direct comparison can be made. The andradite monitor established that all analyses of unknowns, completed during the whole analysis period, were performed under identical probe conditions, as the andradite standard results did not vary outside of analytical uncertainty. 140 104 Total 100 96 36 Cao 35 34 20 Fe203 15 10 16 AI203 12 8 08 T.02 04 0 40 80 120 160 Analysis number Figure Al: Non-calibration standard plotted as oxide concentration against number of analysis (increasing over time). The mean for each set of oxide analyses is represented by a solid horizontal line. Vertical lines demarck analyses collected in a single day. 141 |^ Garnet Figure A2: Grid of analyses on non-calibration andradite. Solid lines represent cracks in the crystal. Points Andr 1-5 were measured on row 3 (end analysis 31). Row-end numbers correspond to analysis numbers of Table A4. Individual analyses are spaced at five microns, both horizontally and vertically. 142 2 e) •Fe row 5 -j whole •Al box 0 0 2 2 ^' d) row 4 row 9 1 - ~ • i ^ 0 * 2 rcw 3 row 8 1 *-• o ^ 0 2 2 b- row 2 row 7 1 i 0 fc^ L 2 «0| row 1 -j row 6 1 0 o 0 1 2 0 1 2 Analytical uncertainty Analytical uncertainty Figure A3: Minimum analytical uncertainty for each oxide is plotted against the IS variation for analyses of the non-calibration andradite collected by rows (Fig.A2). All points are as labelled in j). Elements clustered near (0,0) include Ti, Zr, V, Cr, Mn, Mg, Na. The 1:1 line indicates estimated^analytical uncertainty. Points above the 1:1 line indicate oxides with estimated 102 Total 100 oxides 98 Zr02 Ti02 40 16 Si02 38 Fe203 12 36 10 20 30 10 20 30 Analysis Analysis Figure A4: Oxides, collected thrice per probe session at Andr point 1 (row 3, Fig.A2), are plotted against analysis number. The solid horizontal line is the mean for each set of oxide analyses, and the error bar at the end of each of the lines represents analytical uncertainty. 144 102 AI203 Total 100 oxides 98 Zr02 CaO Ti02 MnO 40 16 SiQ2 38 Fe203 12 36 10 20 30 10 20 30 Analysis Analysis Figure A5: Oxides, collected thrice per probe session at Andr point 2 (row 3, Fig.A2), are plotted against analysis number. The solid horizontal line is the mean for each set of oxide analyses, and the error bar at the end of each of the lines represents analytical uncertainty. 145 16 102 AI203 u Total 100 oxides 12 98 36 Zr02 CaO 35 34 Ti02 MnO 40 16 Si02 38 Fe203 12 36 8 0 10 20 30 10 20 30 Analysis Analysis Figure A6: Oxides, collected thrice per probe session at Andr point 3 (row 3, Fig.A2), are plotted against analysis number. The solid horizontal line is the mean for each set of oxide analyses, and the error bar at the end of each of the lines represents analytical uncertainty. 146 14 102 AI203 12 Total 100 oxides 10 98 36 Zr02 CaO 35 34 Ti02 MnO a8 0.6 16 *Si02 Fe203 12 0 1 0 20 30 0 1 0 20 30 Analysis Analysis Figure Al: Oxides, collected thrice per probe session at Andr point 4 (row 3, Fig.A2), are plotted against analysis number. The solid horizontal line is the mean for each set of oxide analyses, and the error bar at the end of each of the lines represents analytical uncertainty. 147 0 1 0 20 30 0 1 0 20 30 Analysis Analysis Figure A8: Oxides, collected thrice per probe session at Andr point 5 (row 3, Fig.A2), are plotted against analysis number. 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SSOZ HZ ••<0>u.2SOZi- 163 Appendix B: Cation Normalisation Routine % % PROGRAM TI AND.M % NEW VERSION WITH Zr corrected % % MATLAB script to compute titanian andradite % mineral formulas from oxide weight percent data. % % Algorithm is based on 8 cations, 12 oxygens or oxygen and OH equivalents. % Oxides (in order) include: % Si02 Ti02 A1203 Zr02 Cr203 V203 Fe203 FeO MnO MgO CaO Na20 H20 % % DATA is input as row vectors of oxide weight percents [and.dat] % % Computes cations in the following order: % Si Ti Al Zr Cr V Fe3+ Fe2+ Mn Mg Ca Na (H)4 % % Computes Thompson Components as follows: % Andradite (Additive component) Ca3Fe(3+)2Si3012 % TiSi-, AlFe(3+>, ZrSi-, CrFe(3+)-, VFe(3+)-, % TiMgFe(2+)-, FeMg-, MnCa-, MgCa-, Ca (Linearly Dependent), NaFe(3+)2Ca-, H4Si- % %OUTPUT includes: % andecho.out echo file of input data (oxides & total % andcats.out optimized anion distribution (cations & total cats & total O's) % andrecalc.out new oxide totals based on mineral formula (oxides & total)_ % andtcs.out cations represented as thompson component basis % % 'PROGRAM TI_AND.M' delete andlog.out; diary andlog.out; echo off; format short G; % CONSTANTS catn=8; oxyn=T2; % Change this if you change oxide list (Water input as H20) n_cat=13; 164 c=[l 1 2 12 2 2 11112 2]; o=[2 2 3 2 3 3 3 1 1 1 1 1 1]; ox_eq=o./c; % H20 operates as (OH)4 = = Si02 == 2 Oxy's ox_eq(13)=2; atom=[28.086 47.900 26.9815 91.22 51.996 50.942 55.847 55.847 54.938 24.312 40.080 22.9898 1.00797]; mw=atom.*c+ 15.9994*o; % Read in transformation matrix load and_coef.dat; c_matrix=and_coef; % read in data & create matrix of'n' analyses with'm' oxides load and.dat; w=and; rawdat= [w sum(w')']; save echoand.out rawdat -ascii dw=size(w) ncomps=dw(l) n_ox=dw(2) rhs vector=zeros(n cat, 1); x_vector=zeros(n_cat, 1); a _matrix=zeros(n_cat); for i=l:n_cat a_matrix(i,i)=1.0; end % Process individual garnet analyses for j=l :n_comps w(j,7)=w(j,7)+w0,8)*1.1113; w(j,8)=0:0; cats0=(w(j,:).*c./mw)*8/(sum(w(j,:).*c./mw)), ox_tot=sum(catsO. *ox_eq); del_ox= 12-ox_tot; if delox <= 0 % e.g., h2o not present rhs_vector=catsO; rhs_vector(8)=12.0; a_matrix(7,8)=1.0; a_matrix(8, :)=ox_eq; 165 x_vector=(a_matrix\rhs_vector')'; else cats0=cats0/(del_ox/4 +1); cats0(13)=del_ox/(2 - oxJot/8); x_vector=catsO; end % STORE cation normalization catout(j,:)=[x_vector sum(x vector) sum(x_vector.*ox_eq)]; % Recalculate oxide formulas (convert (H4 to H20) mol_mass=(x_vector. *mw./c); mol_mass( 13)=x_vector( 13)*2*mw( 13); wt_new= 100*mol_mass/sum(mol_mass); wtnewout(j,:)=[wt_new sum(wtnew)]; % COMPUTE TCS FROM Xvector tcs(j, :)=[x_vector*c_matrix]; end % Write out optimized cation formula save andcats.out catout -ascii save andrecalc.out wtnewout -ascii save and tcs.out tcs -ascii %END OF PROGRAM - JKR 08/99 revised 11/99 > o o O CD a> crC O • - ro CD CO CN od CN T— od co CD JZ d £ c o £ CD" CN - tu E .co LO co ro x: XI o co xi <" >, LO ?l in cn xi = TJ CN to CD ro CD o o o CO CO CO O CO o o CO T— O T- CD O LO 10 •= c m c o ° LO CN CN h~ OO CO o TJ o d 0) ^. c CO 3 'E CD JL T— CO CN CO CO LO T— ai d to 3 o ® II o s ° c f 03 O •S Q. s E ° .2 + §•« < 1 CD" S CD 0) CD xj CZ -G O * 1- CD CN o ro e c £ *• >«>> •-c o _ xi ro 8 O .2 cn £ "S 5_ « II II \ XI c CD o cn ojQ 03 J.5 -9 X n — —> 3 _ « in 3 >- N 2: O < < _l Z < Z D 5 h- 0- CC < O c : z o: 11 I CD « E - 4) CD 30 TJ CD TJ TJ TJ CD C CD CD © © x> C C C o co j- c "5 fci ° '5 S CO '2 c CO t_ o CO C CO CO CO CD CD E © co CD E 8 © x: to Q. 52 to CO D t_ -5 u. l_ CD CO C0 TJ 2 CO © a CD o TJ 8 © 8 © 8 E CL