The Uranium Mineralization of the , Southeast : Mineralogy,

Geochemistry, Geochronology and Ore-Genetic Model.

By

Valeria V. Li

A thesis submitted to the Graduate Program in Geological Sciences and Geological Engineering

In conformity with requirements for the

Degree of Doctor of Philosophy

Queen’s University

Kingston, Ontario, Canada

April 2016

Copyright © Valeria V. Li, 2016 Abstract

Uranium mineralization of the Quenamari Meseta, Macusani District, SE Peru, is hosted by peraluminous, sillimanite-andalusite-muscovite-biotite of the 12.3 - 6.8 Ma

Macusani Formation of the Miocene-Pliocene Quenamari Group. The main ore mineral, meta- autunite, (Ca[(UO2)(PO4)]2(H2O)6-8), occurs in fractures in association with weeksite and hydrous Mn- and Fe-mineraloids. The absence of U4+ minerals, as well as any hydrothermal alteration associated with the U ore, strongly suggests that meta-autunite is the primary U mineral. LA-ICP-MS U-Th-Pa geochronology of the meta-autunite revealed that the main ore- forming events occurred at 69 ka, 130 ka and 314-317 ka, and probably at ca. 103-113 ka, 210 ka and 400 ka, all long after the last magmatic activity in the area. The obtained ages unambiguously relate U ore formation to low-temperature processes. The δ18O and

δ2H values of the mineralizing fluids, inferred from those of the meta-autunite, range from -21.7

‰ to –12.2 ‰ and from -181 to -123 ‰, respectively, consistent with ore formation from low- temperature meteoric fluids.

The timing of ore formation, as well as the mineralogical and geochemical characteristics of meta-autunite and host rocks, such as REE patterns and alteration assemblages, suggests that

U was leached from the glassy matrix of the rhyolites, transported by meteoric waters and precipitated as meta-autunite. The majority of known deposits are located on the upper walls of active fluvial canyons, which suggests that the geomorphological environment that is now focusing groundwater flow was also favourable for meta-autunite precipitation. Meta-autunite probably precipitated through the mixing of low-temperature fluids and interaction of the uranyl ion with Fe- and Mn-mineraloids.Thus, although the Macusani U deposits are volcanic-hosted, they differ radically from documented magmatic-hydrothermal systems.

ii Acknowledgements

I would like to express my special appreciation to my supervisors Dr. Alan Clark and Dr.

Kurt Kyser. Your guidance will be always remembered.

I would like to thank sincerely the past and presents members of the Queen’s Facility for

Isotope Research, specifically Yulia Uvarova, Paul Alexandre, Evelyne Leduc, Christabel Jean,

April Vuletich and Kerry Klassen, who provided critical guidance in the analytical work. I also thank Brian Joy and Alan Grant of Queen’s University, and as Ravi Sidhu of the University of

Manitoba, for providing valuable assistance with X-ray diffraction and electron microprobe analyses, respectively.

I sincerely thank Don Chipley for providing training and technical assistance with ICP-

MS along the way, for assessing P interference on the isotopes of interest and for all the time he spent discussing the results and interpretations of the data with me. It was a pleasure to work together on such a challenging project.

The present study was generously funded by Cameco Corp., Macusani Yellowcake Inc. and Vena Resources Inc., and by a Society of Economic Geologists Student Research Grant.

I thank many talented industry geologists, particularly David Bent, Walter Cuba, Ted

O’Connor, Dan Brisbin and Laurence Stefan for sharing their knowledge and providing logistical support.

I would like to express my special gratitude to Dr. Clark for the time he spent supervising this project during my last year in the Graduate School despite his difficult personal circumstances. Dr. Clark showed me a level of scientific curiosity and meticulousness I have not imagined before.

iii I thank the staff of the School of Graduate Studies, Writing Centre and Learning

Strategies, Ban Righ Centre of Queen’s University. Particularly, I would like to thank Lisa Webb of the Ban Righ Centre and Kim McAuley, Associate Dean of the School of Graduate Studies.

Kim McAuley’s guidance, mentoring and support will be always remembered.

Last, but not least, I thank my family and friends for constant support. I sincerely thank my parents, my friends Nastia, Claire and Rasine’s family. I am eternally grateful to my husband, Alexey, but most importantly to my daughter, Amy. The birth of my daughter during my years in Graduate School gave me strength and much-needed perspective.

iv Table of contents

Abstract ...... ii

Acknowledgements ...... iii

Table of contents ...... v

List of Figures ...... ix

List of Tables ...... xvii

Chapter 1. Introduction ...... 1

1.1. Geographical and geological setting of the Quenamari Meseta ...... 2

1.2. The Macusani Formation of the Quenamari Meseta ...... 4

1.3. Uranium mineralization of the Quenamari Meseta ...... 7

1.4. Purpose of this thesis ...... 11

1.5. Thesis structure ...... 11

Chapter 2. Methodology ...... 19

2.1. Field methods ...... 19

2.2. Mineral identification methods ...... 19

2.3. Mineral and whole-rock geochemistry ...... 20

2.4. U-series geochronology ...... 22

2.5. Light-stable isotope analysis ...... 26

Chapter 3. The rhyolitic host rocks: stratigraphy, petrography, petrogenesis and

v pre-mineralization hydrothermal alteration...... 30

3.1. Introduction ...... 30

3.2. Stratigraphy of the Macusani rhyolites...... 30

3.3. Petrography of unaltered Macusani rhyolites ...... 32

3.4. Hydrolytic alteration of the Macusani rhyolites ...... 33

3.4.1. Greisen association ...... 33

3.4.2. Argillic alteration ...... 34

3.5. Petrogenesis of the Macusani rhyolites ...... 36

3.6. Conclusions ...... 37

Chapter 4. Uranium mineralization of the Macusani District ...... 57

4.1. Introduction ...... 57

4.2. Distribution of U mineralization ...... 57

4.2.1. Areal distribution and scale of U mineralization ...... 57

4.2.2. Stratigraphic distribution of U mineralization ...... 58

4.3. Mineralogy and geochemistry of the U mineralization ...... 59

4.3.1. Meta-autunite ...... 61

4.3.1. Weeksite...... 65

4.4. Conclusions ...... 66

Chapter 5. U-Th-Pa geochronology of U mineralization ...... 90

vi 5.1. Introduction ...... 90

5.2. Samples selected for geochronology ...... 91

5.3. Age Calculations ...... 91

5.4. U-series ages of the Macusani U mineralization ...... 93

5.5. Discussion ...... 95

5.6. Conclusions ...... 97

Chapter 6. Stable isotope composition of the ore-forming fluid ...... 113

6.1. Introduction ...... 113

6.2. Parameters and assumptions used in fluid composition calculation ...... 114

6.3. Isotope composition of the meta-autunites and the ore-forming fluid ...... 117

6.4. Conclusions ...... 118

Chapter 7. General Summary and Ore-Formation Model ...... 123

7.1. Introduction ...... 123

7.2. Ore mineralogy ...... 123

7.3. Timing of ore genesis ...... 124

7.4. The source of the U ...... 125

7.5. The nature of the ore-forming fluids ...... 127

7.6. The uranium trapping mechanism ...... 129

vii 7.7. Model of ore formation...... 130

7.8. Comparison to other volcanic- and -hosted U deposits...... 132

7.9. Specific Achievements of this Research ...... 134

Chapter 8. Cost analysis ...... 138

References ...... 143

Appendix A Electron microprobe analyses of alteration assemblages ...... 154

Appendix B. Electron microprobe analyses of Mn- and Fe-mineraloids ...... 162

Appendix C. Electron microprobe data for meta-autunites ...... 165

Appendix D. Composition of meta-autunite (ICP-MS) ...... 174

Appendix E. U-Pb isotope ratios ...... 176

Appendix F. U-Th-Pa isotope ratios ...... 178

viii List of Figures

Figure 1.1. A. Google Earth image of the Central Andes; B. Principal tectonic provinces of the

Central Andes and location of the Macusani , a.k.a. Quenamari Meseta, the

focus of this study...... 13

Figure 1.2. Geological map of the study area, modified after Rivera et al. (2011). Rivera et al. do

not recognize the Allincápac Group (Kontak et al., 1990), and therefore the term

“undifferentiated” Permian-through-Lower Jurassic volcanic rocks is used. Further, they do

not distinguish the Picotani Group (Sandeman et al., 1997) ...... 14

Figure 1.3. Generalized stratigraphic column of the Macusani area (based on Kontak, 1985;

Sandeman et al., 1997). Red bodies represent intrusions...... 15

Figure 1.4. View across the Quenamari Meseta looking west at the Quelccaya Ice Cap...... 16

Figure 1.5. Geomorphological features of the Quenamari Meseta. View from the Calvario Real

prospect, looking west, across the canyon of the Río Punco Pato...... 17

Figure 1.6. Location of selected uranium occurrences on the Quenamari Meseta...... 18

Figure 3.1. Schematic stratigraphic column for the eastern part of the Quenamari Meseta, based

on drill-holes at the Tantamaco, Calvario Real and Nuevo Corani prospects. U = uranium

mineralization, wavy-line between units = unconformity...... 39

Figure 3.2. Characteristic drill-core sections of unit “A”. A. Poorly-consolidated, altered

rhyolites (illite-smectite alteration) of unit A, Nuevo Corani prospect; B. Strongly

kaolinitized rhyolites at the contact between unit A and unit B, Nuevo Corani

prospect...... 40

Figure 3.3. Characteristic features of unit B, Macusani rhyolites: A. Field photo of the contact

between unit B and sedimentary basement rocks, U – weak disseminated U mineralization

ix at the contact, Tantamaco prospect; B. Drill-core showing large glassy lapilli with quartz

and biotite phenocrysts, Unit B, Tantamaco prospect...... 41

Figure 3.4. Characteristic features of the Macusani rhyolites, unit C: A. Drill-core section of unit

C, Tantamaco prospect; B. Rhyolite with small white lapilli, Unit C, Nuevo Corani

prospect...... 42

Figure 3.5. Drill-core samples of unaltered Macusani rhyolites A. Unaltered fine-grained

rhyolite, unit B, from the Calvario Real prospect, general view; B. Close up of core sample,

unit B, from the Calvario Real prospect, showing fresh rhyolite with phenocrysts of quartz

(Qz) and biotite (Bt)...... 43

Figure 3.6. Cross-polarized (CL) microscopic images of unaltered Macusani rhyolites. A.

Phenocryst of sanidine (Sa) with silimanite inclusions; B. Broken sanidine (Sa) phenocryst

with sillimanite inclusions and simple twinning...... 44

Figure 3.7. Cross-polarized (CL) microscopic images of Macusani rhyolites. A. Trigonal near-

basal section of tourmaline (Tur) phenocryst. B. Broken glass clast affected by smectite-

illite alteration (flakes at the edge of the clast)...... 45

Figure 3.8. Microscopic images showimng flow texture of the Macusani rhyolites (surface

sample, Nuevo Corani) in plane-polarized transmitted (A) and reflected (B) light. The

glassy matrix of the rhyolite surrounds sanidine (Sa) and quartz (Qz) phenocrysts. The

upper part of the images shows patches of Mn-mineraloids (Mn)...... 46

Figure 3.9. Back-scattered electron image of altered Macusani rhyolite showing partially altered

apatite and voids in rhyolite, drill-hole Ma-Is-Mi-DDH-2010-006, 31 m, Isivilla prospect. 47

Figure 3.10. Drill-core samples affected by greisen alteration A. Void filled with quartz (Qz),

Tantamaco prospect B. Rhyolite with lapilli affected by sericite (fine-grained muscovite). 48

x Figure 3.11. Back-scattered electron images of greisen alteration A. Muscovite (Ms) replacing

topaz (Tpz), drill-hole NC-VR-DDH-2008-023, 118.5 m, Amariza prospect; B. Quartz (Qz)

forms rims around voids in the rhyolite, drill-hole NC-VR-DDH-2008-023, 6.5 m, Amariza

prospect...... 49

Figure 3.12. Drill-core samples affected by strong argillic alteration A. Section of altered (illite-

smectite), friable rhyolites, drill-hole Ma-Cr-Mi-DDH-2010-08; 71-77 m; B. Section of

drill-core showing altered friable rhyolites at the unconformity between unitc B and C; drill-

hole Ma-Ta-Mi-DDH-2010-79; 53-58 m...... 50

Figure 3.13. Back-scattered electron images of intermediate-argillic alteration of the Macusani

rhyolites. A. Patches of illite (white) forming after glassy matrix, 10-Is-30B sample, drill-

hole Ma-Is-Mi-DDH-2010-03, 43.5 m, Isivilla prospect B. Illite crystals (white) and

smectite (dark-grey) forming after glassy matrix, 10-Ta-2 sample, drill-hole Ma-Ta-Mi-

DDH-2010-061, 18.5m, Tantamaco prospect...... 51

Figure 3.14. Back-scattered electron images of argillic alteration of the Macusani rhyolites, drill-

core sample 10-Is-30B, drill-hole Ma-Is-Mi-DDH-2010-03, 43.5 m, Isivilla prospect: A.

Illite (white fibrous crystals) forming after glassy matrix of the rhyolites and sanidine

crystals (Sa), Isivilla prospect B. Illite formed after sanidine (Sa), Isivilla prospect...... 52

Figure 3.15. Chondrite-normalized (Taylor and McLennan, 1985) REE patterns for: A. Unaltered

rhyolites (data from Pichavant et al., 1988b); B. Argillically-altered rhyolites (data from

3.3)...... 53

Figure 4.1. Field photographs of U mineralization: A. Meta-autunite in a subhorizontal fracture

with Fe-Si oxide selvages (black in the photo), uppermost sub-unit of the Macusani

Formation, Pinocho occurrence. B. Subvertical fracture covered with meta-autunite and

xi weeksite in association with Mn-mineraloids, uppermost sub-unit of the Macusani

Formation, Colibri II occurrence. Meta-autunite and weeksite cannot be distinguished

megascopically...... 67

Figure 4.2. Surface hand samples of U mineralization: A. Sample Clb-2, meta-autunite in

fracture and in disseminated form in Macusani rhyolite, Colibri II prospect. B. Sample Mac-

206, meta-autunite in veinlet (0.5-1 cm) in rhyolite, Tantamaco prospect...... 68

Figure 4.3. Mn-Fe mineraloids: A. Clb-1 surface sample, showing aggregates of black Mn-

mineraloids and yellow meta-autunite crystals (small yellow patches), Colibri II prospect.

B. Back-scattered electron image of Mn-Fe mineraloids (dark-grey) enclosing prismatic

meta-autunite (M-aut) crystals, surface sample, Pinocho prospect...... 69

Figure 4.4. Representative X-ray powder diffraction patterns (Cu radiation) of ore samples 10-Is-

17 and 10-Is-19 (Isivilla), Pi-1 (Pinocho) and Chi-6-1 (Chilcuno), showing peaks of meta-

autunite (M-aut), plagioclase (Pl), and unidentified mica (Mc)...... 70

Figure 4.5. Microscopic images of U mineralization, Macusani district, Tantamaco prospect,

surface sample. A. Plane-polarized transmitted light image of meta-autunite filling vein. B.

Cross-polarized transmitted light image of meta-autunite (yellow) and weeksite (blue)

filling vein...... 71

Figure 4.6. Back-scattered electron (BSE) images of U mineralization, Macusani district,

Tantamaco prospect, surface sample. A. Meta-autunite fills a void adjacent to an unaltered

sanidine phenocryst in rhyolite. B. Meta-autunite filling a void in rhyolite...... 72

Figure 4.7. Back-scattered electron (BSE) images of U mineralization, Macusani district,

Tantamaco prospect, surface sample. Meta-autunite partially replaces an apatite phenocryst

and fills a contiguous void in the rhyolite...... 73

xii Figure 4.8. Back-scattered electron (BSE) images of U mineralization, Macusani district. A.

Meta-autunite (white) and Mn-mineraloids (Mn, grey) fill a fracture in rhyolite. Nuevo

Corani prospect, surface sample. B. Meta-autunite (white) and weeksite (dark-grey area ain

middle of photo) fill a fracture in the rhyolite. Colibri II prospect, surface sample...... 74

Figure 4.9. Cross-polarized transmitted light microscopic image of moraesite (blue) and meta-

autunite (yellow). Sample NC-3, Nuevo Corani prospect, drill-hole NC01-06-08,

32.6 m...... 75

Figure 4.10. Representative X-ray diffraction powder pattern of the 10-Is-30wc sample, drill-

hole Ma-Is-Mi-DDH-2010-03, 43.5 m, Isivilla prospect, showing peaks of moraesite (Mrst)

and plagioclase (Pl)...... 76

Figure 4.11. Back-scattered electron images of moraesite, Macusani rhyolite, drill-hole Ma-Is-

Mi-DDH-2010-03, 43.5 m, Isivilla prospect A. Moraesite fills a fracture in rhyolite B.

Moraesite enclosing unaltered sanidine phenocryst...... 77

Figure 4.12. Back-scattered electron (BSE) images of microcrystals of meta-autunite enclosed in

Fe-mineraloids (dark-grey). Surface sample, Pinocho prospect. Red spots and numbers

show locations of EMPA analyses (Table 4.5.) ...... 78

Figure 4.13. Simplified chemical compositions of the Macusani meta-autunites EMPA and ICP-

MS data (Tables 4.3 and 4.6) and Eastern Desert meta-autunites (Abd El-Naby and

Dawood, 2008) presented on a triangular diagram. Red star represents ideal stoichiometric

meta-autunite with 7 water molecules...... 79

Figure 4.14. Chondrite-normalized (Taylor and McLennan, 1985) REE patterns for meta-

autunites from the Macusani area (ICP-MS data fromTable 4.8)...... 80

xiii Figure 5.1. Representative samples selected for geochronological analysis. Samples Pi-2, Chi-6

and Clb-2 were obtained by splitting meta-autunite veins longitudinally. Samples Clb-2-1

and Mac-206 are polished cutoffs of meta-autunite veins in rhyolite. Most samples are

meta-autunites, but samples Clb-2 and Clb-2-1 are meta-autunites with subordimate

weeksite. Note that samples Mac-207 (Nuevo Corani prospect) and Tut-1 (Tuturumani

prospect) used in the study are not shown. More informataion about the samples is

presented in Table 5.1...... 98

Figure 5.2. X-ray powder diffraction patterns (Cu radiation) of selected samples used in the

geochronology study, showing peaks of meta-autunite (M-aut), weeksite (Wkt), plagioclase

(Pl) and unidentified mica (Mc)...... 99

Figure 5.3. Concordia [231Pa/235U] – [230Th/234U] activity ratio diagram and U-Th-Pa age for the

Tut-1 sample, from the Tuturumani prospect. The squares represent individual analyses

with error margins...... 100

Figure 5.4. Concordia [231Pa/235U] – [230Th/234U] activity ratio diagram and U-Th-Pa ages for the

Pi-2 sample, from the Pinocho prospect. The squares represent individual analyses with

error margins...... 101

Figure 5.5. Concordia [231Pa/235U] – [230Th/234U] activity ratio diagram and estimated U-Th-Pa

age for the Mac-206 sample, from the Tantamaco prospect. The squares represent individual

analyses with error margins...... 102

Figure 5.6. Concordia [231Pa/235U] – [230Th/234U] activity ratio diagram and estimated U-Th-Pa

age for the Chi-6 sample, from the Chilcuno prospect. The squares represent individual

analyses with error margins...... 103

xiv Figure 5.7. Concordia [231Pa/235U] – [230Th/234U] activity ratio diagram and estimated U-Th-Pa

age for the Mac-207 sample, from the Nuevo Corani prospect. The squares represent

individual analyses with error margins...... 104

Figure 5.8. Concordia [231Pa/235U] – [230Th/234U] activity ratio diagram and estimated U-Th-Pa

age for Clb-2-1 sample, from the Colibri II prospect. The squares represent individual

analyses with error margins...... 105

Figure 5.9. Concordia [231Pa/235U] – [230Th/234U] activity ratio diagram and estimated U-Th-Pa

age for the Clb-2 sample, from the Colibri II prospect. The squares represent individual

analyses with error margins...... 106

Figure 5.10. Location of several uranium occurrences in the Quenamari Meseta with determined

U-Th ages (average U-Th ages from Table 5.2)...... 107

Figure 6.1. Fractionation factors as a function of temperature for δ18O as calculated by the

incremental method (-1-) (Zheng, 1991, 1993) and the smectite proxy (-2-) (from Savin and

Lee, 1988)...... 119

Figure 6.2. The isotopic compositions of meta-autunites and of the associated fluids calculated

using O and H smectite-water fractionation factors (Savin and Lee, 1988; Capuano, 1992) at

150C, and composition of the fluid calculated using O incremental fractionation factor (data

from Table 6.2)...... 120

Figure 7.1. Proposed evolution of the Macusani U deposits. (A) 12.3-6.8 Ma: the peraluminous

U-enriched rhyolites of the Macusani Formation were erupted. (B) Tertiary tectonic uplift

caused faulting, significant erosion and canyon incision in the area. (C) Around 3.5 Ma,

glaciers formed in the area; alternating glacial and interglacial periods increased erosion and

meteoric water circulation, leaching U from the Macusani rhyolites and transporting it along

xv fractures. (D) The main episodes of U ore-formation took place ca. at 69 ka, 130 ka, 314-

317 ka, and probably at ca. 103-113 ka, 210 ka and 400 ka...... 136

xvi List of Tables

Table 2.1. Drill-holes used in the study. AZ – the direction the hole was drilled, where 0 degrees points north; DIP – dip of the drill-hole in degrees, Drilled – the total length of the drill-hole in meters. Elevation is presented in metres above sea level. na – data not available...... 28

Table 2.2.Operating conditions and data acquisition parameters for U-series isotopic ratio determination during LA-ICP-MS analysis...... 29

Table 2.3. Activity ratios for in-house uraninite U-Pb standard...... 29

Table 3.1. Major and minor element composition (EMPA) and stoichiometry of smectite from

Isivilla (Is-30), Tantamaco (10-Ta-32), and Nuevo Corani (10-NC-2)...... 54

Table 3.2. Major and minor element composition (EMPA) and stoichiometry of ferric F-illite from Isivilla (10-Is-30B), Tantamaco (10-Ta-32), and Nuevo Corani (10-NC-2)...... 55

Table 3.3. REE concentrations of the Macusani rhyolites from Tantamaco (10-Ta-1, 10-Ta-8),

Calvario Real (10-Cr-4), Isivilla (10-Is-5), and Nuevo Corani (10-NC-5, 10-NC-14, 10-NC-26)

(present study, analysed by ICP-MS), with data from Pichavant et al. (1988b) for whole-rock rhyolites (MN3-330) and Macusanite glass (JV1) ...... 56

Table 4.1. Resources of the Quenamari Meseta, at a cut-off grade of 75 ppm U (Foreman, 2012;

Young and Nupen, 2013; Henkle and Associates, 2014)...... 81

Table 4.2. Chemical composition in wt.%. of Mn-mineraloids from Colibri II and Nuevo Corani and Fe-mineraloid from Pinocho (EMPA data); na- not analysed...... 81

Table 4.3. Major and minor element compositions (in wt.%) of meta-autunites from the

Macusani area. Analysed by EMPA, (*) – analysis by ICP-MS at Queen’s University...... 82

Table 4.4. Formula units for meta-autunites from various locations (calculated from data in Table

4.3)...... 83

xvii Table 4.5. Major element compositions of meta-autunite crystals (Pinocho-1, Fig. 4.12), in wt.

%, EMPA data. Analysis ID – the numbers stands for the spot number in Fig. 4.12 and the number of each individual analysis. For example Pinocho 4-5 stands for the analysis 5 at the spot number 4 at Fig. 4.12...... 84

Table 4.6. Major and minor element compositions (in wt.%) of meta-autunite from the Macusani

District, analysed by ICP-MS at Queen’s University...... 85

Table 4.7. Formula units for meta-autunites (calculated from the data in Table 4.6)...... 86

Table 4.8. Minor and trace element concentrations (in ppm) of meta-autunites

(ICP-MS data)...... 87

Table 4.9. Weeksite: Major element composition (in wt.%) and formula units.

Analysed by EMPA...... 89

Table 5.1. Samples selected for geochronological analysis. SVF denotes subvertical mineralized fractures and SHF subhorizontal mineralized fractures. Flat surfaces of the samples obtained by splitting the meta-autunite veins...... 108

Table 5.2. U-series activity ratios and apparent U-Pa and U-Th ages for meta-autunite samples from the Macusani U occurrences...... 109

Table 6.1. Parameters used in the calculation of the I-18O index ...... 121

Table 6.2. Isotopic compositions of meta-autunites and composition of the fluid calculated from meta-autunites using smectite fractionation factors (Savin and Lee, 1988; Capuano, 1992) for

150C ...... 122

Table 7.1. Main characteristics of volcanic- and granite-hosted U deposits and prospects...... 137

Table 8.1. Cost of the laboratory work...... 139

Table 8.2. Cost of the field work ...... 140

xviii Table 8.3. Cost of labour ...... 140

Table 8.4. Cost of conference and industry meetings participation ...... 141

Table 8.5. Tuition and student fees ...... 141

Table 8.6. Summary of the PhD project costs ...... 142

xix Chapter 1. Introduction

Uranium mineralization was discovered in the Macusani district of southeastern SE Peru, in the late- 1970’s, when the Instituto Nacional de Energia Nuclear (National Nuclear Energy

Institute of Peru: IPEN), conducted a countrywide exploration program for U. As a result of radiometric prospecting and trenching over an area of over 600 km2, more than 60 radiometric anomalies were identified on the Quenamari Meseta. In the mid-1980’s, U3O8 prices fell from

40$/lb to 11$/lb and exploration on the meseta was terminated. However, in the 2000’s, when prices for U were rapidly increasing, attaining 140$/lb in 2007 (International Atomic Energy

Agency, 2014), the area once again received attention. Following detailed exploration and, most importantly, drilling programs, conducted in 2009 by Vena Resources Inc. and Macusani

Yellowcake Inc, the International Atomic Energy Agency (IAEA) estimated an inferred overall resource of 6.5-13 M lbs U3O8 at 0.12-0.24 % U3O8. Currently, the resources of the Macusani deposits are estimated as following: measured and indicated 95.2 Mt at 248 ppm U3O8 (51.9

Mlbs U3O8), and inferred resources 130.0 Mt at 251 ppm U3O8 (72.1 Mlbs U3O8), at a cut-off grade of 75 ppm U (Foreman, 2012; Young and Nupen, 2013; Henkle and Associates, 2014).

The almost entirely volcanic-hosted uranium occurrences of the Macusani district were interpreted as “volcanic-type”, i.e., fundamentally magmatic-hydrothermal, deposits by Arribas and Figueroa (1985), Leroy and Aniel (1992), IAEA (2009), Dahlkamp (2010) and Nash (2010).

However, they exhibit numerous aberrant features, such the absence of U4+ assemblages and directly associated hydrothermal alteration.

1 1.1. Geographical and geological setting of the Quenamari Meseta

The area of study, the Quenamari Meseta, a.k.a. the Macusani volcanic field (centred at

Latitude 13° 57ʹ S; Longitude 70°37ʹ W), is located in Department, southeastern Peru, ≈50 km to the north of Titicaca. The area belongs to the Cordillera de Carabaya segment of the

Central Andean Eastern Cordillera (Cordillera Oriental; Figs. 1.1 A, B).

The Permian-to-Quaternary igneous rocks of the Cordillera Oriental are assigned to the

Inner Arc magmatic domain of the post-Paleozoic Central Andean (Clark et al., 1983;

1990). The Inner Arc domain and the oceanward Main Arc domain, the latter underlying the

Cordillera Occidental (Western Cordillera) and Altiplano, are both ensialic (James, 1971; Clark et al., 1973), having evolved upon a Proterozoic-through-Paleozoic crystalline basement.

However, they exhibit very distinct magmatic and tectonic features. Magmatic activity in the

Main Arc domain was entirely subduction-related and has been quasi-continuous since the mid-

Triassic. Igneous rocks of this domain are predominantly of mantle origin, with contributions from the upper and middle continental crust (Clark et al., 1990), and with calc-alkaline to weakly-alkaline affinities (Dostal et al., 1977). In contrast, magmatism in the Inner Arc domain occurred in several widely separated episodes during the Mesozoic and Cenozoic, involved both mantle and locally predominant upper crustal sources and ranged from strongly peralkaline to strongly peraluminous (Clark et al., 1990).

The regional geology of the Cordillera de Carabaya has been described by Laubacher

(1978), Kontak (1985) and Sandeman (1995). The geology of the wider Macusani district, as compiled by Rivera et al. (2011), is shown in Fig. 1.2. This does not, however, accommodate geochronological data for local intrusive and volcanic rocks provided by Kontak et al. (1990),

Cheilletz et al. (1992) and Sandeman et al. (1997). These are incorporated in the simplified

2 stratigraphic column presented in Fig. 1.3. The area is underlain by a thick sequence (10-15 km) of marine sediments (mainly semi-pelites and psammites) of to age. This was followed by the deposition of Upper Paleozoic limestones, sandstones and shales, intercalated with alkali-basaltic volcanic flows of the Permian Mitu Group. In the Triassic-to-

Early Jurassic (ca. 205-235 Ma), magmatic activity took place in the form of meta- to peraluminous granitoid bodies including the San Gabán , Coasa, Aricoma, and Limbani plutons of the Carabaya Batholith. Subsequently, still in the Jurassic (ca. 185 Ma: Kontak et al., 1990), peralkaline syenites and trachyandesites of the Allincápac Group were emplaced, and in the

Cretaceous (ca. 80-70 Ma), minor granodioritic intrusions were emplaced. Late (ca. 38

Ma) uplift, which occurred in response to the thick-skinned Incaic orogeny (Farrar et al., 1988), was followed by rapid mid-Tertiary erosion of the axis of the proto-Cordillera Oriental.

Tertiary peraluminous volcanics subsequently erupted into the evolving Crucero, Picotani and Macusani intermontane basins, and stocks and dykes intruded the margins of the basins.

Sandeman et al. (1997) proposed a new stratigraphic unit, “The Crucero Supergroup”, which incorporates the upper Oligocene to-lowermost Miocene Picotani Group and the Lower -to

Upper Miocene Quenamari Group. Rocks of the Picotani Group are represented by rhyodacites intercalated with K-rich and ultrapotassic, lamproitic and lamprophyric flows, whereas the Quenamari Group is dominated by rhyolites and two-mica syenogranites. Almost all known

U anomalies in the study area are associated with the Macusani Formation, the youngest major unit (12.3-6.8 Ma) of the Quenamari Group, underlying much the Quenamari Meseta.

The uplift of the Central Andes from the late Oligocene through to the Quaternary caused a gradual change of climate and rainfall in the area (Poulsen et al., 2010). Today, seventy percent of the rainfall on the meseta occurs during the austral summer, from November to March, when

3 easterly flow brings moisture from the Amazon Basin (Garreaud, 2003); the average annual precipitation in the Macusani area is about 3000 mm (http://www.worldweather online.com

/Macusani-weather-averages/Puno/PE.aspx acquired January 7, 2016).

The high altitude of the Central Andes (≈ 4000 – 6000 m a.s.l. overall) and the large amounts of moisture rising from the Amazon Basin constitute conditions ideal for glacier formation in a tropical region. The Quelccaya Ice Cap (Fig. 1.4), which overlies the western half of the Quenamari Meseta and Macusani volcanic field, is the largest ice mass in the tropics. It now covers an area of 70 km2 and reaches an elevation of 5645 m a.s.l. Although there is an abundance of data on the Late Quaternary (past 30-20 ka) history of the ice cap (Thompson et al., 1985; Goodman et al., 2001), its earlier, Plio-Pleistocene history is uncertain. Clapperton

(1983) argued that the Central Andes record at least five glacial Plio-Quaternary episodes, including the last glacial maximum at 1.8 Ma, as well as four episodes at 170-140 ka, 80-30 ka,

30-16 ka and 16 -10 ka, respectively. This tentative chronology is, however, based on largely

Northern Hemispheric data.

Neogene tectonic uplift, in combination with fluvial activity, caused considerable subplanar erosion of the surface and canyon incision into the Macusani volcanic field. The canyons are deep (150-250 m) and narrow (300-500 m in width) (Fig. 1.5) and some are probably related to major structures in the area. The most significant canyon is the valley of Ríos

Macusani and San Gabán, which drains the Quenamari Meseta to the Amazon Basin.

1.2. The Macusani Formation of the Quenamari Meseta

The Quenamari Meseta, largely coextensional with the Macusani volcanic field, is a

≈4400 m a.s.l. plateau, recessed into the axis of the Cordillera de Carabaya. Extrusive and

4 intrusive rhyolites of the Macusani Formation, the youngest unit of the Quenamari Group

(Sandeman et al., 1997), dominate the Macusani field. Estimation of the total volume of the rhyolitic flows is problematic as the Quelccaya Ice Cap covers a significant part of the

Quenamari Meseta. However, according to Cheilletz et al. (1992), the Macusani Formation covers an area of 860 km2, the maximum thickness of the sequence is 500m and the volume of volcanic rocks is 430 km3.

The Macusani Formation disconformably overlies deformed Devonian Ananea Formation and Carboniferous Ambo Formation marine sediments, molassic sediments and basaltic flows of the Permian Mitu Group (Kontak, 1985; Clark et al., 1990), the Jurassic peralkaline andesites of the Allincápac Complex (Kontak et al., 1990), and the Oligocene-Lower Miocene rhyodacitic volcanics and plutons of the Picotani Group (Sandeman et al., 1997). A number of monzogranitic intrusions of the Picotani Intrusive suite (the Quebrada Centilla Stock, Revancha Dyke,

Ninahuisa Stock) and rhyolitic intrusions of the Quenamari Intrusive suite (Nevado Ollo

Quenamari Plug, Cerro Cajo Orjo plug and Chaccaconiza Stock) crop out on, and to the south of, the southern margin of the Quenamari Meseta.

The Macusani Formation is a gently-dipping (≤3° NE) sequence of whitish-grey, entirely subaerial, crystal-rich (avg. 45-50%, locally up to 62% vol. crystals), peraluminous rhyolites.

Irregular dips locally reflect the pre-eruption topography of the Macusani basin (Pichavant et al.,

1988a). The rhyolites contain abundant pumice clasts (0.5-10 cm), lithoclasts (limestones, pelites, quartzites and rhyolites) and weakly-phyric bodies (0.5-25cm). They are relatively uniform in texture, but separate units can be established on the basis of erosional surfaces and concentrations of larger fragments of pumice at the base of units. According to

40Ar/39Ar data, the formation consists of a number of flows of variable thickness, although two

5 major eruptive cycles are recognized at 10±1 Ma and 7±1 Ma (Cheilletz et al., 1992), thereby dividing the Macusani Formation into Lower and Upper subunits. However, the Instituto

Geológico, Minero y Metalúrgico del Perú (INGEMMET) divides the volcanics into three members: Chacaconiza, Sapanuta and Yapamayo (De la Cruz et al., 1996). Despite the difference in nomenclature, all authors agree that U mineralization is concentrated in the upper part of the rhyolitic pile. Uranium mineralization is hosted by two series of fractures: subvertical, parallel to the columnar jointing; and gently-dipping (10-40°) faults, which cut the Upper

Macusani subunit (Arribas and Figueroa, 1985; Cheilletz et al., 1992).

The rhyolites have traditionally been described as ash-flows, or (Francis,

1956; Noble, 1984). The very high peraluminosity and crystal content imply extremely high viscosity of the extruded material, but thick individual flows can be traced for distances of more than 10 km (Sandeman et al.; 1994). Sandeman et al. (1994) suggested that the rhyolites, which may be classified as crystal-lapilli tuffs, were extruded as frothy debris-flows, emphasizing the absence of primary volcaniclastic bedform structures, welding and tricuspate glass shards, together evidence for the absence of an initial Plinean eruption stage.

The Macusani Formation has an exceptional mineralogical composition. The main phenocrysts are quartz (7-15 vol.%), sanidine (15-20 vol.%), plagioclase (10-15 vol.%), biotite

(2-4 vol.%), muscovite (0-1 vol.%), andalusite (0-1 vol.%), cordierite (0-2 vol.%) and apatite (0-

0.5 vol.%) (Pichavant et al., 1988a). Phenocrysts are 1-2 cm in size, and are largely unaltered but commonly broken. Accessory minerals include sillimanite, tourmaline, spinel, zircon, monazite, topaz, ilmenite and rutile. The glassy matrix (45-60 vol.%) is fine-grained, partially devitrified, and locally altered to clay minerals. Obsidian glass (“macusanite”), originally interpreted as tektitic, is a common component of the rhyolites. It forms shards (0.5-5cm) of green to yellow

6 colour and can be also found in overlying alluvial sediments as pebbles. The Macusani rhyolites are mineralogicaly consistent throughout the Quenamari Meseta, from the oldest members to the youngest (Pichavant et al., 1988a).

The unusual mineralogical composition of the Macusani Formation reflects its unusual chemical composition. The rhyolites are characterized by a narrow range of SiO2 (71-75 wt.%), high contents of Al2O3 (14-16 wt.%), alkalis (NaO+K2O+Li2O+Rb2O+Cs2O=7-9 wt.%), lithophile metals (Sn, W, Ta, Be) and “volatile” elements (up to 100 ppm B and 4100 ppm F), and low FeO, MgO, CaO and TiO2. Exceptional concentrations include those of Be (up to 50 ppm), Li (835 ppm), and Rb (up to 596 ppm) (Pichavant et al., 1988b). The high index of peraluminosity (A/CNK > 1.2) indicates that the rhyolites were generated through partial melting of a pelitic crustal source, and are related to “S-type” two-mica (Noble et al.,

1984; Pichavant et al., 1988b).

1.3. Uranium mineralization of the Quenamari Meseta

Although U mineralization was discovered on the Quenamari Meseta in the late-1970’s, the first descriptions date to the mid-1980’s. In a pioneering report, Flores et al. (1983) described four uraniferous areas on the Quenamari Meseta , viz., Huiquiza, Tantamaco, Corani and

Chaccaconiza (Fig. 1.6). They observed primary (pitchblende) and secondary (gummite: a field term for yellow U minerals) U mineralization in subhorizontal fractures. The presence of pitchblende was recorded at the “Kiquitian” I, II and III occurrences in the Huiquiza area.

Subsequently, Herrera and Rosado (1984) documented five U occurrences, Huiquiza I, II,

III, Cuychine and Tantamaco, all situated close to the eastern margin of the meseta (Fig. 1.6).

They observed subhorizontal (5° NE) mineralized horizons up to 5 m in thickness and 100 in

7 lateral extent, enriched in meta-autunite and torbernite (Huiquiza 1), and disseminated meta- autunite in rhyolites of high porosity as well as meta-autunite in fault zones, where the rhyolite is affected by intense kaolinization and mylonitization. Uranium-mineralized horizons are described as associated with Fe oxides (hematite, limonite crusts) and Mn oxides, all assumed to be strictly supergene. These authors proposed several constraints for U mineralization at the

Macusani area, both structural (faults and fractures) and sedimentological-lithological

(mineralogical composition of, and voids in, rhyolites). On the basis of field observations and limited laboratory data, Herrera and Rosado (1984) proposed a preliminary ore-formation model for the U occurrences, arguing that U was oxidized and leached from the U-enriched Macusani rhyolites, transported in the form of U6+ during wet seasons and then, when physico-chemical conditions changed, precipitated as autunite. The authors, concluding that the U minerals were

“very recently” formed, emphasised the role of the oxidizing surface conditions and climate

(short wet and long dry periods and high insolation) in the ore-forming process. Although terming the meta-autunite and torbernite “secondary minerals”, the authors did not record the presence of precursor U minerals, such as uraninite or pitchblende.

Arribas and Figueroa (1985), in contrast, subsequently postulated the occurrence of pitchblende at one occurrence, viz. Pinocho, and assigned a strictly supergene, replacive, origin to the major U minerals. These authors described the Esperanza I, II, III, Chilcuno VI, Kihitian I,

II, III, Calvario, and Chapi Alto and Bajo occurrences (Fig. 1.6). Uranium mineralization was observed to occur in the upper units of the Macusani volcanics, especially those enriched in smoky quartz, biotite and andalusite, and also as disseminations in the rhyolites. The authors distinguished two types of U mineralization: primary (pitchblende) and secondary “gummite”.

Botryoidal bodies of gummite, interpreted to be after pitchblende, were observed. The

8 pitchblende was described as blackish and with low reflectance in polished section, but no X-ray or analytical data were provided. The pitchblende is described as intimately associated with pyrite and melnikovite (i.e., collomorphic pyrite/marcasite), as well as with Mn oxides. In the

Macusani U occurrences, the gummite was described as comprising autunite (the main U mineral), phosphyuranylite, uranophane, billietite and becquerelite, associated with psilomelane, a generic term for poorly-crystalline Mn oxides. However, no X-ray or other data were provided in support of these mineral identifications.

Arribas and Figueroa (1985) further argued for petrographic similarities between the U occurrences of the Macusani area and those associated with Hercynian peraluminous granites in

France, but formally advocated an exhalative, synvolcanic origin. They suggested that residual,

“deuteric” hydrothermal fluids, enriched in U and volatiles, were circulating along fractures shortly after eruption and deposited pitchblende and pyrite through reduction in the presence of

H2S or CO2, or due to temperature, pH and Eh change in a zone where hydrothermal fluids mixed with meteoric waters. Later, meteoric waters altered and oxidized pitchblende and redeposited U in the form of strictly supergene gummite.

Simultaneously, Valencia and Arroyo (1985) were studying the geochemical aspects of the Macusani rhyolites and also described the U mineralization. They sampled the Pinocho,

Chilcuno and Chapi occurrences (Fig. 1.6) and, in general, their description of the U mineralization is very similar to that of Arribas and Figueroa (1985). They also distinguished primary mineralization, consisting of botryoidal pitchblende and coffinite (noted for the first time), in association with pyrite and chalcopyrite, from secondary mineralization consisting of autunite, meta-autunite and renardite. No petrographic or X-ray diffraction data were provided, but electron microprobe data for “pitchblende” samples from an unspecified locality were

9 provided by a third party, showing a wide range of UO2 content of 39.40-79.57 wt.% as well as unusually high P2O5 contents of 0.29-23.43 wt.%.

Clark et al. (1990) for the first time documented the overall geological, geochronological and metallogenetic context of the U mineralization on both the Quenemari Meseta and the nearby Picotani Meseta. A supergene origin was accepted for the meta-autunite deposits on the basis of the studies of Arribas and Figueroa (1985) and Valencia and Arroyo (1985), as the terminal event in the evolution of a world-class polymetallic (Sn, W, Zn, Ag, U) subprovince at the northwestern extremity of the Central Andean Inner Arc domain. The most important U mineralization in the Macusani district was interpreted to have developed shortly after eruption of the youngest succession of rhyolitic flows at 7±1 Ma. A magmatic-hydrothermal origin for the postulated precursor pitchblende veins and disseminations was considered to be supported by the occurrence of CO2 – rich secondary fluid inclusions in apatite and radiation-damaged smoky quartz in the immediate host-rocks of two U occurrences, with trapping temperatures in the range

226-285 °C (A.H. Clark, unpublished data). Subsequently, in an unpublished report, Clark

(2006) proposed that such warm, post-magmatic brines leached uranium from U-enriched volcanic glass and subsequently precipitated pitchblende through mixing with cold, superficial meteoric waters.

A recent INGEMMET (Instituto Geológico, Minero y Metalúrgico del Perú) report (Rivera et al., 2011) provides an overview of the U mineralization, but provides few new data. Critically, however, it makes no reference to the IPEN publications that report the occurrence of pitchblende, thereby implicitly concurring with the work of Herrera and Rosado (1984). The authors conclude that the U was concentrated through supergene processes.

10 1.4. Purpose of this thesis

The goals of the present study are to determine the nature of the U mineralization in the

Macusani district and to propose an ore-genetic model. The study integrates mineralogy, petrography, geochemistry and geochronology with detailed geological observations.

The key issues to be addressed include:

1. The nature of the U mineralization

2. The source of the U in the system

3. Timing of ore genesis, and

4. The nature of the fluids involved in ore formation

These observations will be integrated to generate a comprehensive genetic model, and to

compare the Macusani U mineralization to that documented from other regions.

1.5. Thesis structure

Chapter 2 documents the field and analytical methods used in the study. Chapter 3 includes field and petrographic observations as well as geochemical data on the Macusani rhyolites. The possible sources of the U are discussed. In Chapter 4 the nature of U mineralization in the Macusani area is discussed. Analytical data on the mineralogy and geochemistry of the U ores are presented. Chapter 5 is focused on determining the timing of U ore-formation. Uranium-Th and U-Pa ages obtained by laser ablation (LA) inductively-coupled plasma mass spectrometry (ICP-MS) are used to correlate meta-autunite precipitation with the major Neogene and Quaternary geological and climatic events in the Central Andes. In Chapter 6 the nature of the ore-forming fluid is discussed. In addition, the possibility of using light-stable isotopic data for meta-autunite to obtain information on the nature of ore-forming fluids is

11 evaluated. Chapter 7 discusses the results of the present study and provides an integrated ore- genetic model for the U deposits of the Macusani area. A new model is compared to existing models for the U ore-formation in the Macusani area. In addition, we compare Macusani occurrences to other volcanic- and granite-hosted U deposits such as Strel’tsovskoe, Dornot and

Sierra Peña Blanca. Chapter 8 reports the cost analysis of the study.

12

Figure 1.1. A. Google Earth image of the Central Andes; B. Principal tectonic provinces of the Central Andes and location of the Macusani volcanic field, a.k.a. Quenamari Meseta, the focus of this study.

13

Figure 1.2. Geological map of the study area, modified after Rivera et al. (2011). Rivera et al. do not recognize the Allincápac Group (Kontak et al., 1990), and therefore the term “undifferentiated” Permian-through-Lower Jurassic volcanic rocks is used. Further, they do not distinguish the Picotani Group (Sandeman et al., 1997)

14

Figure 1.3. Generalized stratigraphic column of the Macusani area (based on Kontak, 1985; Sandeman et al., 1997). Red bodies represent intrusions.

15

Quelccaya Ice Сap

Figure 1.4. View across the Quenamari Meseta looking west at the Quelccaya Ice Cap.

16

Figure 1.5. Geomorphological features of the Quenamari Meseta. View from the Calvario Real prospect, looking west, across the canyon of the Río Punco Pato.

17

Figure 1.6. Location of selected uranium occurrences on the Quenamari Meseta.

18 Chapter 2. Methodology

2.1. Field methods

The present study is based on field observations of numerous outcrops and of approximately 2500 m sections of fourteen drill-holes at five localities on the Quenamari Meseta during the 2009 and 2010 field seasons (Table 2.1). The mineral compositions, textures, alteration and structures of the rhyolites, as well as the distribution of the U mineralization were examined. More than 300 hand samples and core samples of the mineralized and barren rhyolites were collected from outcrops and drill-holes at the Calvario Real, Chapi, Chilcuno, Colibri II,

Isivilla, Nuevo Corani, Pinocho, Tantamaco, Amariza and Tuturumani localities (Fig. 1.6).

Additional samples were provided by Cameco Corporation and Macusani Yellowcake Inc.

2.2. Mineral identification methods

Mineral assemblages were identified in 80 polished thin-sections using transmitted- and reflected- light microscopy. Scanning electron microscopy was performed on the thin-sections using an Amray 1830 instrument and a FEI Quanta MLA 650 environmental scanning microscope (ESEM) at the Queen’s Facility for Isotope Research (QFIR), Queen’s University,

Canada. Prior to X-raying, whole rock samples were crushed and U-mineral separates were handpicked. X-ray powder diffraction data were collected with a Panalytical X’pert Pro diffractometer, using Cu K-alpha radiation (30 kV accelerating voltage, 15 mA operating current). Standard abbreviations for mineral names used in this paper are those of Whitney and

Evans (2010).

19 Clay mineral identification

Clay minerals were separated from crushed and sieved rock samples. To extract clay-size material, crushed samples were placed in plastic beakers with deionized water and treated with an ultrasonic probe for 90 seconds. Suspended matter was transferred to plastic test tubes, which were then placed in a centrifuge. Following the centrifuging and decanting of the tubes, heavy material at the bottom of the test tubes was loosened with a little deionized water and poured onto glass plates. Following drying on a hotplate at 60 oC, the clays were X-rayed, treated with ethylene glycol vapour, and then X-rayed again.

For the ethylene glycol treatment, ethylene glycol was poured into the base of a desiccator, and the clay-coated glass plates were placed on its shelf. The samples were left in the desiccator overnight. The X-ray powder patterns of the air-dried and glycolated clay samples were compared, differences therein indicating expandable, smectite-group species.

The identification of the clay minerals was based on the morphology of the minerals in backscattered electron (BSE) microscopic images, electron microprobe analyses (see details below) and XRD patterns.

2.3. Mineral and whole-rock geochemistry

The major element compositions of minerals were determined using a JEOL JXA-8230 electron microprobe at QFIR and a Cameca SX 100 electron microprobe (EMPA) at the

University of Manitoba, Canada, both operating in wavelength-dispersion mode and with an accelerating voltage of 15 kV, a specimen current of 10 nA, and a beam size of 5 μm. To achieve representative data, five grains were analyzed from each sample, with 5 points on each grain.

Analytical results are accurate to 2% for major elements and 5% for minor elements (<1 wt.%).

20 The following standards were used for the elements sought in different minerals:

Uranium minerals (meta-autunite and weeksite): Na-albite, Ca, Si –diopside, U – UO2, Fe - fayalite, Ti –titanite, Pb – PbTe, P – apatite, K – orthoclase, Th – ThO2, Al – andalusite, Mn – spessartine.

Mn-mineraloids: Na-albite, Ca, Si –diopside, Fe -fayalite, Ti –titanite, P – apatite, K – orthoclase, Al – andalusite, Mg – olivine, Mn – spessartine, Sr – SrTiO3.

Silicate minerals (clay minerals): Na-albite, Ca, Si –diopside, Fe -fayalite, Ti –titanite, P – apatite, K – orthoclase, Al – andalusite, Mg – olivine, Mn – spessartine, F – riebeckite, Cr – chromate, V – VP2O7, Cl – tugtupite.

The concentrations of minor and trace elements of meta-autunite and whole-rock samples were collected by high-resolution inductively-coupled plasma mass spectrometry (HR-ICP-

MS) and optical emission spectroscopy (ICP-OES). In this work, water with a resistivity of 18.2

M and purified using a Milli-Q (Millipore) system was used throughout sample preparation and cleaning procedures. Hydrochloric and nitric acids used for all reagent preparation were purified by distillation in PTFE stills.

Prior to meta-autunite analysis an aliquot of 0.02 to 0.05 g from the sample was weighed and dissolved in 1 mL of concentrated HNO3 at 130C for at least 24h. The samples were then evaporated to dryness, dissolved in 2% HNO3 and spiked with In. The final weight of the sample was 1 mg.

Whole-rock samples of the host rhyolites were first crushed and pulverised to <68µm. An aliquot of 0.1 g was then weighed and digested using 4 mL HF (SeaStar Chemicals), 1 mL HCl and 1 mL HNO3 in an Anton Paar microwave digestion system. The microwave digestion system worked at power of 1200W and a maximum temperature of 210°C, but the pressure was not

21 monitored. The heating period was 10 minutes, followed by 35 minutes hold period, then the power of the microwave digestion system switched to 0w and held for 15 minutes. The resulting solution was evaporated to dryness, redissolved in concentrated HNO3 at 180C to remove any residual material, dried and dissolved in 2% HNO3, and spiked with In for measurement of the elemental concentrations. The final weight of the sample was 10 mg.

Samples of meta-autunites and whole-rocks were analysed with a Finnigan MAT

ELEMENT2 HR-ICP-MS and Thermo Scientific iCap 6000 Series HR-ICP-OES at QFIR.

Different elements were measured at different resolution powers according to the procedure used at QFIR to avoid possible mass interferences. The instruments are optimized daily for maximum sensitivity and stability. Indium was used as an internal standard during the measurements. For external calibration, standards were prepared with concentrations of 0 ppt (blank), 50 ppt, 100 ppt, 300 ppt, 500 ppt, 1 ppb, 5 ppb, 10 ppb, 50 ppb, 100 ppb, 300 ppb, 500 ppb and 1 ppm.

2.4. U-series geochronology

U-series isotopic ratios were measured by laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) using an ESI NWR 193 nanometer Ar-F Excimer laser ablation system coupled to a Finnigan Neptune MC-ICP-MS at QFIR. Operating conditions for the HR-ICP-MS and laser used during analyses are summarized in Table 2.2. The Ar-F excimer laser ablation system is equipped with illumination, a microscope viewing system, and a sample chamber. Sample preparation requires placing a flat surface within the focal plane of the laser.

The sample chamber is moved within the laser focal plane by computer-controlled motors.

Parameters including spot-size, laser power, pulse rate and fluence were optimized during analysis. Both spot- and raster- mode techniques were used. Five to 12 analyses were performed

22 for each meta-aunitine sample. During analysis, the mineral is ablated and measured with 20 scans, each representing a very small amount of the sample. Polished offcuts of meta-autunite veins and natural flat surfaces obtained by splitting of veins were used in the study. A description of the samples selected for the U-series analyses is presented in Chapter 5.

The Thermo Finnigan Neptune is a doubly-focusing, plasma source high resolution (HR)

MC-ICP-MS with a moveable array of nine Faraday collectors, four on either side of a fixed position central cup, and one high-sensitivity secondary electron multiplier (SEM).

A dynamic approach was used to measure the low abundances of 230Th, 234U, 232Th and

231Pa isotopes. Half-masses on either side of low abundance peaks were also measured and baseline intensities interpolated from the half-masses. Instrument tuning consists of daily adjusting plasma gas flows and electrostatic lens settings by the instrument software to maximize the U, Th and Pa signal intensities, while minimizing 238U16O+ intensities. The isotopic data were collected in low-resolution mode to obtain significant intensities of the low abundance isotopes, such as 234U, 230Th and 231Pa, and to resolve the molecular interferences 207Pb31P on 238U, 204Pb31P on 235U, 200Hg31P on 231Pa, 201Hg31P on 232Th and 199Hg31P on 230Th (Hg commonly occurs in the

Ar plasma gas). Typical signals were 3-10 V for 238U, 1000’s to 10,000’s cps for 230Th, and 100 to 1000’s cps for 231Pa.

A solution with U/P ratio similar to the meta-autunite samples was measured to assess P interference on the various isotopes of interest. A desolvating interface (Apex, ESI, Omaha,

Nebraska) was used to imitate the dry plasma conditions of laser ablation. The contributions to the 230Th and 231Pa signals from HgP interferences measured on the U-P solution with Apex are

2.8 cps and 2.5 cps, respectively, which indicates about 0.1% contribution to the 230Th signal and less than 2.5% contribution to the 231Pa signal. The evaluation of the molecular interference to

23 the sample signals is problematic because molecular interference magnitudes will be affected by the sample matrix. As systematic errors, they may bias the 230Th/234U and 231Pa/235U ratios to near 0.1% and 2.5% high, respectively.

Finally, the contribution of initial 230Th and 231Pa was evaluated. The Macusani rhyolites, the proposed source of the U for meta-autunites, have Th/U elemental ratios ranging from 0.5 to

2 (Pichavant et al., 1988; Leroy and George-Aniel, 1992). The 230Th half-life is 8,000 y and the age of the Macusani rhyolites is 6.8 -12.3 Ma (Cheilletz et al., 1992), which means that 230Th should be in secular equilibrium with U, giving a 230Th/238U ratio of 1.68×10-5. Thorium leached from the rhyolites should have a 230Th/232Th ratio of 3×10-5 to 8×10-6 or slightly higher, as 230Th may be leached more easily because it resides in radioactive decay-damage sites. Measured

230Th/232Th ratios of the Macusani meta-autunite are as high as 5, indicating a maximum contribution of initial 230Th of 0.002 to 0.0004%. Thorium and Pa are characterized by similar chemistries and a similar contribution of initial 231Pa is expected. Thus, measured 231Pa/230Th is typically 0.0X, which indicates a contribution of initial 231Pa of 0.2 to 0.04 %.

Sample quality assurance and quality control Quality control of the laser ablation method is challenging due to the destructive nature of the procedure, so that reproducibility for a single run cannot be assessed. Due to an inability to both ablate and measure the same material twice and the inhomogeneity of the natural samples, the LA ICP-MS results are characterised by relatively high errors.

As no standards were available to measure low-abundance Pa and Th isotopes, samples of known ages were used as reference materials. Calibration of U-Th-Pa system was conducted using an in-house uraninite standard with a known U-Pb age of 1028+/-2 Ma with up to 2% discordance (measured by Isotope Dilution-Thermal Ionization Mass Spectrometry, ID-TIMS, at

24 University of Toronto, Table 2.3). The discordance indicates Pb loss and emplies that some Th and Pa may also have been also lost at the same time. All measured [230Th/234U] and [231Pa/235U] activity ratios of the uraninite sample were below unity, i.e., below secular equilibrium. This may result from mass bias, element bias or loss of Th and Pa from the uraninite. The values nearest to secular equilibrium (sample B) are more likely to represent mass bias and element bias alone, while those farther from secular equilibrium are probably a result of combined mass bias, element bias and Th and Pa loss (samples A, C and D). For sample B, the [234U/234U] value is

3% low, but within error of secular equilibrium, [231Pa/235U] is 10-15% low and [230Th/234U] is

8% low.

Data processing and error propagation

The raw isotope intensity data were corrected to the 238U intensity, because it gave the best signal and corresponded to expected natural abundances. The peak tail correction of the ablation data was performed using baseline intensities interpolated from the half-masses. The interpolated baseline intensities normalized to 235U and 238U intensities were subtracted from the measured values of 230Th, 234U, 232Th and 231Pa.

The standard deviation was calculated for each ratio based on the number of the scans used in the calculations. Each measurement consisted of twenty scans, but scans with low intensities of the U-series isotopes (238U intensity below 1V) were excluded from the calculations.

Error propagation includes daily SEM calibration, yield errors, random errors, i.e., half- mass measurments for baselines and sample measurement errors. Errors are propagated as ratios, because ratios are more constant that the individual isotope ablation signals. Systematic errors,

25 such as possible phosphide interference and calibration using the in-house uraninite standard, are not included in error propagation.

2.5. Light-stable isotope analysis

The main U mineral of the Quenamari Meseta and the main focus of the present study is meta-autunite, hydratil calcium uranyl phosphate. The conventional procedure for the O isotope analysis of phosphates includes PO4 group extraction, as this group is characterized by strong bonds unaffected by low-temperature alteration processes (Firsching, 1961; Crowson et al. 1991;

O’Neil et al. 1994; Stephan, 2000). Phosphate samples (e.g., apatite, bones or teeth) are dissolved in HF, followed by PO4 group precipitation in the form of Ag3PO4 by Tollens' reagent.

Oxygen is then extracted from Ag3PO4 samples by a fluorization technique.

In meta-autunite, with the general formula Ca[(UO2)(PO4)]2(H2O)6-8, oxygen occurs in

2+ 3- 2+ 3- three sites – UO2 , PO4 and H2O. Both UO2 and PO4 sites involve strong bonds resistant to low-temperature alteration. For that reason, un unconventional method, which permits analysis

2+ 3 of both UO2 and PO4 groups, was used. Meta-autunite samples (n=34) from various locations were pulverized and split for O and H analysis. Before the O analysis, samples were heated at

130C to remove absorbed water and weakly-bonded interlayer H2O groups. Then the samples were placed in a nickel reaction vessel, such as are routinely used for silicates and oxides.

Oxygen was extracted from the samples using the BrF5 technique of Clayton and Mayeda

(1963). The accuracy of the extraction was evaluated by the gas yield, measured for each sample.

Yields for meta-autunites were around 100%.

26 The O isotope compositions of the meta-autunites were determined using a dual inlet

Finnigan MAT 252 isotopic ratio mass spectrometer (IRMS). Results were corrected according to internal laboratory (QFIR) standards using as BS127 and NIS8493 for oxygen.

Hydrogen isotopic compositions were measured on a Thermo Finnigan TC/EA and a

Delta plus XP IRMS after preheating at 100oC for an hour to remove adsorbed water. Obtained

H isotope compositions were corrected according to the internal laboratory (QFIR) standards,

Georgia clay and UofM.

Oxygen and H isotope ratios are reported in δ notation in units of per mil (‰) relative to the Vienna Standard Mean Ocean Water (V-SMOW). Analyses of standards are reproducible to

± 0.2 for δ18O and ± 3‰ for δ2H.

27

Table 2.1. Drill-holes used in the study. AZ – the direction the hole was drilled, where 0 degrees points north; DIP – dip of the drill-hole in degrees, Drilled – the total length of the drill-hole in metres. Elevation is presented in metres above sea level. na – data not available.

Prospect Drill Hole # AZ DIP Drilled Easting Northing Elevation

Tantamaco Ma-Ta-Mi-DDH-2010-061 90 45 220.3 334784 8460704 4387

Tantamaco Ma-Ta-Mi-DDH-2010-065 90 45 199.3 334988 8460708 4378

Tantamaco Ma-Ta-Mi-DDH-2010-057 90 45 250.5 334587 8460722 4412

Tantamaco Ma-Ta-Mi-DDH-2010-079 90 45 220 334399 8460409 4403

Isivilla Ma-Is-Mi-DDH-2010-006 360 45 71.7 333300 8462050 4150

Isivilla Ma-Is-Mi-DDH-2010-004 90 45 49.1 333200 8462000 4150

Isivilla Ma-Is-Mi-DDH-2010-003 360 45 85.2 333300 8462200 4150 NC-VR-DDH-2008-023 Amariza (NC-06-01/08) na na 250.65 328450 8464600 4465 MC-NC-VR-DDH-2008-017 Nuevo Corani (NC-03-02/08) 124 30 86.2 327452 8465397 4510 MC-NC-VR-DDH-2008-006 Nuevo Corani (NC-01-06/08) 135 20 140.2 327179 8464537 4495

Calvario Real Ma-CR-Mi-DDH-2010-008 90 45 178.1 331900 8463357 4463 MC-Ta-VR-DDH-2007-001 Tantamaco (Ta-01-01-07) 95 45 80.1 334952 8460945 4347

Nuevo Corani NC-13-01-08 135 60 190 327816 8464998 4470

Nuevo Corani NC-02-06/08 140 25 60.4 327187 8464995 4499

28 Table 2.2.Operating conditions and data acquisition parameters for U-series isotopic ratio determination during LA- ICP-MS analysis.

Neptune MC-ICP-MS Sample gas Ar, 0.98 L/min Cool gas 17.0 L/min Auxiliary gas 0.9 L/min Forward Power 1250 W Reflected Power <5W Sample measurement time 20 cycles, 4 sec each Half-mass measurement time 5 cycles, 4 sec each

Ar-F 193nm Excimer Laser Spot Size 10-15 μm Laser power 30-40% Fire rate 10 Hz Fluence 0.84 J/cm2 Carrier gas He, 1.2 L/min

Table 2.3. Activity ratios for in-house uraninite U-Pb standard

Sample [234U/238U] error [230Th/238U] error [231Pa/235U] error [230Th/234U] error

A 0.890 0.003 0.813 0.002 0.71 0.04 0.916 0.003

B 0.997 0.004 0.917 0.012 0.85 0.05 0.920 0.011

C 0.906 0.002 0.813 0.003 0.54 0.05 0.897 0.032

D 0.994 0.004 0.899 0.005 0.37 0.14 0.901 0.005

29 Chapter 3. The rhyolitic host rocks: stratigraphy, petrography, petrogenesis and pre-mineralization hydrothermal alteration.

3.1. Introduction

The entirely rhyolitic Macusani Formation (6.8 - 12.3 Ma) of the Quenamari Group

(Sandeman et al., 1997) almost exclusively hosts the U mineralization of the Quenamari Meseta.

While general information on the age and larger-scale stratigraphic relationships of the Macusani

Formation is provided in Chapter 1, more specific details of its stratigraphy, petrography, and petrogenesis and its relation to the U mineralization are presented in this chapter.

3.2. Stratigraphy of the Macusani rhyolites

The stratigraphy, mineralogy and geochronology of the Macusani rhyolites are extensively documented by Noble et al. (1984), Pichavant et al. (1988a), Clark et al. (1990),

Cheilletz et al. (1992) and Sandeman et al. (1994, 1997), as well as by INGEMMET geologists

(De la Cruz et al., 1996).

Three volcanic units, A, B and C (Fig. 3.1) were recognized during the course of this study, based on field observations of numerous outcrops and of approximately 2000 m of intersections from fourteen drill-holes at five localities (Chapter 2, Table 2.1). The rhyolites of the oldest unit, A, are observed in drill-hole NC-06-01/08 from the Nuevo Corani area (Fig. 1.6), unconformably overlying metapelites and volcanics of the Paleozoic-Mesozoic basement. These rhyolites are white-to-grey, poorly consolidated and affected by strong argillic (illite-smectite) alteration (Fig. 3.2A). The crystal content in this unit is lower than those of units B and C,

30 constituting 20-30 vol.%, and is dominated by phenocrysts of quartz and biotite, associated with strongly altered lapilli (illite-smectite alteration). The unit exceeds 35 m in thickness in the

Nuevo Corani area, but its lower contact is not there intersected. The contact with overlying unit

B is marked by an erosional surface, with strong kaolinitic alteration at the contact (Fig. 3.2B).

Volcanic unit B was intersected in all of the studied drill-holes and crops out at numerous localities on the Quenamari Meseta; it unconformably overlies both unit A (Fig. 3.2B) and the basement rocks (Fig.3.3A). The contact with the latter reflects the extremely incised topography of the pre-eruption terrain, the rhyolites at the contact containing xenoliths of strongly-altered

Mesozoic or Paleozoic rocks. Disseminated U mineralization is observed at the base of unit B, near the contact with the basement rocks at the Tantamaco occurrence (Fig.3.3A). The rhyolites of this unit are fine-grained, white-to-grey, well consolidated, and crystal-rich (30-45 vol.%).

Phenocrysts are dominated by quartz, sanidine, biotite, muscovite and andalusite. Lapilli are common, varying in size from 0.5 to 10 cm, being sub-equant or elongated, white, and coarse- grained, with a porous, altered matrix. Large phenocrysts (>2mm) of quartz and biotite are observed in the glassy lapilli (Fig. 3.3B). The lithoclasts include limestones, pelites, quartzites, andesites and rhyolites. The stratigraphic section of unit B incorporates several intervals of lapilli-rich (2% to 15%) rhyolites that probably mark unconformities. Toward the bottom of the unit, the size and abundance of lapilii increase, reaching 10 cm and 30 vol.%, respectively. The thickness of unit B in drill-hole NC-06-01/08 at the Nuevo Corani prospect is 175 m. Unit B rhyolites host U mineralization in subvertical and subhorizontal fractures, as well as in disseminated form.

Unit C, the youngest unit in this sector of the meseta, is separated from the rhyolites of unit B by an unconformity marked by an erosional surface (Fig. 3.4A). The rhyolites of unit C

31 are brown-to-grey, weakly-to-moderately altered (illite-smectite) (Fig. 3.4B). They contain 40-50 vol.% crystals, the main phenocrysts consisting of sanidine, quartz, biotite and muscovite. As in unit B, the base of the unit is rich in lapilli and lithoclasts. The thickness of unit C in the eastern part of the meseta varies from 40 m in the Nuevo Corani area to 70 m in the Tantamaco area.

3.3. Petrography of unaltered Macusani rhyolites

The proportion of phenocrysts varies from 20 vol.% for the rhyolites of Unit A up to at least 45 vol.% for units B and C. However, no significant variation in the mineral species and compositions among the different units was observed either in the course of the present study or by earlier workers.

The main phenocrysts are quartz (7-15 vol.%), sanidine (15-20 vol.%), plagioclase (10-

15 vol.%), biotite (2-4 vol.%) and muscovite (0-1 vol.%), all 0.01-2 cm in size. They are largely unaltered (Figs. 3.5A, B). Smaller phenocrysts of andalusite (0-1 vol.%), cordierite (0-2 vol.%) and apatite (0-0.5 vol.%) are also common. Accessory magmatic minerals include sillimanite, tourmaline (schorl-dravite series), spinel, zircon, monazite, topaz, ilmenite and rutile.

Plagioclase shows polysynthetic twins (Fig. 3.6A) under the microscope and sanidine shows simple twins (Fig. 3.6B). Sanidine encloses acicular crystals of sillimanite, their orientation coinciding with planes of cleavage (Fig. 3.6A). The feldspar phenoscrysts are largely unaltered, but commonly broken. Biotite occurs in the form of brown platy crystals (0.01-2 mm), some deformed. Muscovite forms smaller crystals (up to 0.7 mm) and some of them are also bent. Apatite occurs in the form of small bipyramidal crystals. Andalusite shows pink pleochroism and good cleavage. Tourmaline shows green pleochroism and trigonal cross-section

32 (Fig. 3.7A). Zircon forms bipyramidal crystals with radioactive haloes. Glass clasts are common, their size ranging from 0.01mm to 4 mm (Fig. 3.7B).

The matrix of the rhyolites is fine-grained and consists of extremely small quartz, sanidine and plagioclase crystals intergrown with volcanic glass. Some rhyolite samples exhibit a flow texture (Fig. 3.8A,B), with biotite and muscovite phenocryst basal planes oriented in the plane of flow. The observations of the present study are in agreement with those of Sandeman et al. (1994), in that no microscopic and megascopic textures indicative of ash-flow processes, such as fiamme, welding or tricuspate shards, are present.

3.4. Hydrolytic alteration of the Macusani rhyolites

This alteration of the Macusani rhyolites varies from insignificant, with unaltered sanidine phenocrysts and matrix glass, to moderate and intense. In terms of mineralogical composition and origin, alteration products fall into two broad categories: (i) weak-to-intense argillic alteration, apparently not associated with lithophile metal concentrations; and (ii) more local, high-temperature and presumably earlier, “greisen-type”. Neither facies is U-enriched.

Microscopic study also shows that some apatite phenocrysts are altered and partially or completely dissolved (Fig. 3.9).

3.4.1. Greisen association

In hand sample, the greisen-type alteration manifests itself in the form of voids filled with euhedral quartz (Fig. 3.10A) and sericite, fine-grained muscovite covering the surfaces of fractures, and brown sericitic patches (Fig. 3.10B). SEM study showed that the alteration

33 incorporates euhedral topaz (Fig. 3.11A), muscovite and quartz filling voids in the rhyolites (Fig.

3.11B).

Alteration of this type typically forms at temperatures in the range 250-400°C through the incursion of acidic magmatic-hydrothermal brines with high HF/H2O fugacity ratios. Although widely associated with lithophile-metal mineralization, e.g., Sn and W, it characteristically precedes ore deposition, and the absence of, e.g., cassiterite or wolframite in the Sn- and W-rich

Macusani rhyolites in not, therefore, unexpected. This hydrolytic alteration was not, however, followed by lithophile-metal concentration.

3.4.2. Argillic alteration

The widespread intermediate-argillic alteration of the rhyolites manifests itself in a loss of coherence and a change of colour from grey to white (Fig. 3.12A, B) or brownish-grey. The lapilli are preferentially affected by this alteration, rather than the matrix of the rhyolites.

Advanced-argillic alteration in form of kaolinite-quartz is observed only in drill-hole NC-06-

01/08 at the contact between units A and B (Fig. 3.2B), implying a control by major discontinuaties in the rhyolitic succession.

Microscopic study of argillically-altered rocks shows that the glassy matrix is partially devitrified and locally altered to flakes 0.1 mm in size, which appear colourless in plane light and bright yellow to green in crossed polars. The SEM study showed that clay minerals form radial clusters of fibrous and tabular crystals (1-40μm), replacing the matrix of the rhyolites and sanidine phenocrysts (Fig. 3.13A,B; 3.14A,B). Obsidian clasts are also affected by argillic alteration; alteration rims develop around the glass clasts (Fig. 3.7B). The argillic alteration, affecting the matrix of the rhyolites, probably causes the fragility of the rhyolites.

The argillic assemblages consist of two distinct clay minerals: illite and smectite.

34 The clay minerals were identified based on morphology, XRD and chemical data as non- expandable fibrous illite and expandable smectite. (For details of clay mineral identification see

Chapter 2 and Appendix A).

The Ca-smectite (CaO 1.53-1.95 wt. %) is characterized by a narrow range of SiO2

(46.39-48.76 wt. %), but wide ranges of Al2O3 (11.06-28.83 wt.%) and FeO (0.77-21.12 wt. %)

(Table 3.1). Smectite from the Nuevo Corani occurrence has the lowest Al2O3 (11.06 wt.%) and highest FeO (21.12 wt.%) concentrations. The chemical compositions of samples 10-Is-30 and

10-Ta-32 correspond to Ca montmorillonite, whereas that of sample 10-NC-2 corresponds to nontronite. The illite is characterized by exceptionally high F (7.75-8.65 wt. %) and FeO (9.21-

12.84 wt. %), and by narrow ranges of SiO2 (43.44-44.75 wt. %), Al2O3 (22.85-24.56 wt.%), and

K2O (9.01-9.63 wt.%) (Table 3.2). The high FeO content of the Macusani illite is similar to that described by Eggleton and Gerald (2011) from Muloorina, South Australia.

Rhyolites from the Tantamaco, Calvario Real, Isivilla and Nuevo Corani and Chapi prospects, affected by the argillic alteration, are depleted in total REE (12-36 ppm) relative to unaltered rhyolites (65 to 120 ppm, Table 3.3, concentrations of Ho, Er, Tm, Yb and Lu, are below the detection limits of the ICP-MS method). The normalized REE patterns of the rhyolites

(Pichavant et al., 1988b and this study) are relatively flat with slight negative Eu anomalies

(Figs. 3.15A, B) caused by plagioclase fractionation. The REE pattern of the obsidian

(“macusanite”) is different from those of the rhyolites and can be described as “gull-wing”, i.e., relatively flat with a strong Eu anomaly (Fig. 3.15A), reflecting extreme plagioclase fractionation (Pichavant et al., 1988a).

Rhyolites from the Tantamaco, Calvario Real, Isivilla and Nuevo Corani and Chapi U prospects affected by argillic alteration are characterized by a weak positive Ce anomaly (Fig.

35 3.15B), which probably records postmagmatic low-temperature alteration of the rhyolites.

Tetravalent Ce is less mobile under oxidizing conditions than REE3+(Akagi and Masuda, 1998) and tends to stay with the solid phase. The mobility of REE under oxidizing conditions also explains the lower total concentration of REE in the altered rhyolites relative to the unaltered:

REE may have been released from the glassy matrix of the rhyolites by oxidizing fluids.

3.5. Petrogenesis of the Macusani rhyolites

The petrogenesis of the highly-peraluminous Macusani magmas could be explained by two different models: (i) assimilation of metapelitic material by mantle-derived magmas, or (ii) direct partial melting of an aluminous crustal source (Noble et al., 1984). However, the first hypothesis is not supported by petrographic observation, as there is no exposed mafic volcanism in the area, and no exotic mafic igneous inclusions or xenoliths in the Macusani rhyolites.

Pichavant et al. (1988b) concluded that Macusani magmas were produced by direct partial melting of the continental crust. However, the source of heat was probably hot, mantle-derived mafic magmas.

The high index of peraluminosity (>1.2), recording the presence of Al-rich phases such as muscovite, andalusite, cordierite and sillimanite, the presence of sillimanite in the restite, and the

87 86 high Sr/ Sri ratios (whole-rock 0.72555: Noble et al., 1984; Pichavant et al., 1988b) suggest that Macusani rocks were formed by the partial melting of an aluminous crustal source.

Moreover, the high δ18O values (12.1-12.4 ‰: Pichavant et al., 1988b) indicate that the protoliths were metapelitic. The chemical and mineralogical homogeneity of the Macusani rhyolites on the entire Quenamari Meseta and the small amount of restite (5%) suggest that similar, but not identical protoliths were melted and that insignificant crystal fractionation occurred before

36 eruption. The minor volume of strongly-fractionated melt represented by the volcanic glass,

“macusanite”, exhibits a characteristic composition different from the main Macusani rhyolites, including its REE pattern (Fig. 3.15A). Macusanite contains high Li (3,450 ppm), B (1,950 ppm), F (13,300 ppm) and Cl (427 ppm) (Pichavant et al., 1988b), and is strongly enriched in Sn,

W, Be and Nb as well as in incompatible elements such as U, Rb and Cs, and is correspondingly depleted in Th, Zr and REE.

Peraluminous melts were traditionally regarded as being generated in continental crust at relatively low temperatures and under H2O-saturated conditions. However, these conditions would cause crystallization of the magma before it reaches the surface (Clarke, 1981). In the case of the Macusani rhyolites, the mineralogical relationships indicate that the melt was generated at high temperatures (800°C) and under H2O-undersaturated conditions (Pichavant et al., 1988), an environment now considered normal for strongly peraluminous intrusive and extrusive rocks

(Patiño-Douce, 1999; Sylvester, 1998).

3.6. Conclusions

According to Cheilletz et al. (1992), the volume of the Macusani Formation is approximately 430 km3. The U content of the rhyolites is exceptionally high, with an average of

20-28 ppm in unaltered rhyolites (Leroy and Aniel, 1992; H.A. Sandeman and A.H. Clark, unpublished data), with that of the obsidian bodies reaching 160 ppm (H.A. Sandeman and A.H.

Clark, unpublished data). In contrast, the average U content of typical granites is 3-4.8 ppm

(Turekian, 1961; Taylor, 1964). The present study shows that U-hosting phases, mainly the glassy matrix of the rhyolites, with average U content of 15 ppm (Leroy and Aniel, 1992), as well as the glass clasts in the rhyolites, are affected by intermediate-argillic alteration. Although

37 the illite-smectite alteration is not spatially related to the U mineralization, it could have promoted release of U from the glassy matrix of the rhyolites over millions of years. The combination of these factors makes the Macusani Formation an enormous potential source of leachable U and thus a favourable environment for the formation of U deposits.

38

Figure 3.1. Schematic stratigraphic column for the eastern part of the Quenamari Meseta, based on drill-holes at the Tantamaco, Calvario Real and Nuevo Corani prospects. U = uranium mineralization, wavy-line between units = unconformity.

39 A

10 cm Drill hole NC-06-01/08; 217-224m

B

Contact Unit A

Unit B

Drill hole NC-06-01/08; 215.5m 3 cm

Figure 3.2. Characteristic drill-core sections of unit “A”. A. Poorly-consolidated, altered rhyolites (illite-smectite alteration) of unit A, Nuevo Corani prospect; B. Strongly kaolinitized rhyolites at the contact between unit A and unit B, Nuevo Corani prospect.

40 A Unit B

U

Contact

Basement Tantamaco prospect

B 3 cm

Lapilli

Drill-hole Ma-Ta-Mi-DDH-2010-079; 168.5m

Figure 3.3. Characteristic features of unit B, Macusani rhyolites: A. Field photo of the contact between unit B and sedimentary basement rocks, U – weak disseminated U mineralization at the contact, Tantamaco prospect; B. Drill- core showing large glassy lapilli with quartz and biotite phenocrysts, Unit B, Tantamaco prospect.

41 A 3 cm

Unit C Unit B

Drill-hole Ma-Ta-Mi-DDH-2010-079; 53.1m

B 2.5cm

Unit C Lapilli

Drill-hole NC-03-02/08; 81.5m

Figure 3.4. Characteristic features of the Macusani rhyolites, unit C: A. Drill-core section of unit C, Tantamaco prospect; B. Rhyolite with small white lapilli, Unit C, Nuevo Corani prospect.

42 A 2 cm

Drill-hole Ma-CR-Mi-DDH-2010-08; 96 m

B

Lapilli 1 cm

Bt

Qz

Drill-hole Ma-CR-Mi-DDH-2010-08; 109.2 m

Figure 3.5. Drill-core samples of unaltered Macusani rhyolites A. Unaltered fine-grained rhyolite, unit B, from the Calvario Real prospect, general view; B. Close up of core sample, unit B, from the Calvario Real prospect, showing fresh rhyolite with phenocrysts of quartz (Qz) and biotite (Bt).

43 A

Sa

Mac-106

B

Sa

Mac-106

Figure 3.6. Cross-polarized (CL) microscopic images of unaltered Macusani rhyolites, Chilcuno VI prospect. A. Phenocryst of sanidine (Sa) with silimanite inclusions; B. Broken sanidine (Sa) phenocryst with sillimanite inclusions and simple twinning.

44 A

Tur

Mac-109

B Glass clast

Mac-106

Figure 3.7. Cross-polarized (CL) microscopic images of Macusani rhyolites, Chilcuno VI prospect. A. Trigonal near-basal section of tourmaline (Tur) phenocryst. B. Broken glass clast affected by smectite-illite alteration (flakes at the edge of the clast).

45 A

Mn

Sa

Qz

Mac-202

B

Mn

Sa

Qz

Mac-202

Figure 3.8. Microscopic images showing local flow texture of the Macusani rhyolites (surface sample, Nuevo Corani) in plane-polarized transmitted (A) and reflected (B) light. The glassy matrix of the rhyolite surrounds sanidine (Sa) and quartz (Qz) phenocrysts. The upper part of the images shows patches of Mn-mineraloids (Mn).

46 Ap

Ms

10-Is-6

Figure 3.9. Back-scattered electron image of altered Macusani rhyolite showing partially altered apatite and voids in rhyolite, drill-hole Ma-Is-Mi-DDH-2010-006, 31 m, Isivilla prospect.

47 A 1.5 cm

Qz

Lapilli

Drill-hole Ma-Ta-Mi-DDH-2010-057; 152 m

B 2 cm

Sericite

Drill-hole Ma-Is-Mi-DDH-2010-06; 22.5 m

Figure 3.10. Drill-core samples affected by greisen alteration A. Void filled with quartz (Qz), Tantamaco prospect B. Rhyolite with lapilli partially replaced by sericite (fine-grained muscovite).

48 A

Ms

Ms Tpz

Tpz

10-NC-18

B

Qz Qz

Sa

10-NC-2

Figure 3.11. Back-scattered electron images of greisen alteration A. Muscovite (Ms) replacing topaz (Tpz), drill- hole NC-VR-DDH-2008-023, 118.5 m, Amariza prospect; B. Quartz (Qz) forms rims around voids in the rhyolite, drill-hole NC-VR-DDH-2008-023, 6.5 m, Amariza prospect.

49 A

Drill-hole Ma-Cr-Mi-DDH-2010-08; 71-77 m

B contact

Unit B Unit C

Drill-hole Ma-Ta-Mi-DDH-2010-079; 53-58 m

Figure 3.12. Drill-core samples affected by strong argillic alteration A. Section of altered (illite-smectite), friable rhyolites, drill-hole Ma-Cr-Mi-DDH-2010-08; 71-77 m; B. Section of drill-core showing altered friable rhyolites at the unconformity between unitc B and C; drill-hole Ma-Ta-Mi-DDH-2010-79; 53-58 m.

50

A

matrix

Ilt Qz

Is-30B

B Qz

Ilt

Sme matrix

10-Ta-2

Figure 3.13. Back-scattered electron images of intermediate-argillic alteration of the Macusani rhyolites. A. Patches of illite (white) forming after glassy matrix, 10-Is-30B sample, drill-hole Ma-Is-Mi-DDH-2010-03, 43.5 m, Isivilla prospect B. Illite crystals (white) and smectite (dark-grey) forming after glassy matrix, 10-Ta-2 sample, drill-hole Ma-Ta-Mi-DDH-2010-061, 18.5m, Tantamaco prospect.

51 A

Ilt Ilt

Ilt Sa Ilt

10-Is-30B

B

Ilt

Sa

10-Is-30B

Figure 3.14. Back-scattered electron images of argillic alteration of the Macusani rhyolites, drill-core sample 10-Is- 30B, drill-hole Ma-Is-Mi-DDH-2010-03, 43.5 m, Isivilla prospect: A. Illite (white fibrous crystals) forming after glassy matrix of the rhyolites and sanidine crystals (Sa), Isivilla prospect B. Illite formed after sanidine (Sa), Isivilla prospect.

52

A. 1000

327

100 325

MH8 MH6 10

MH4 chondrite MH3 1 MH5 REE unaltered rhyolite/REE rhyolite/REE unaltered REE 324 obsidian glass 0 La Ce Nd Sm Eu Gd Dy Er Yb

B. 100

Tantamaco

Nuevo Corani

10 Calvario Real

Isivilla

Chapi 1

0 REE altered rhyolite/REE chondrite rhyolite/REE altered REE La Ce Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Figure 3.15. Chondrite-normalized (Taylor and McLennan, 1985) REE patterns for: A. Unaltered rhyolites (data from Pichavant et al., 1988b); B. Argillically-altered rhyolites (data from 3.3).

53 Table 3.1. Major and minor element composition (EMPA) and stoichiometry of smectite from Isivilla (Is-30), Tantamaco (10-Ta-32), and Nuevo Corani (10-NC-2).

Sample ID 10-Is-30  10-Ta-32  10-NC-2 

SiO2 46.77 1.76 48.76 1.40 46.39 3.61

Al2O3 24.63 1.05 28.83 2.84 11.06 4.90

TiO2 0.04 0.03 0.04 0.03 0.03 0.02 FeO 0.77 0.13 2.46 0.46 21.12 7.22 MnO 0.05 0.02 0.05 0.02 0.03 0.13 MgO 0.49 0.08 0.40 0.05 0.95 0.12 CaO 1.64 0.09 1.53 0.30 1.95 0.30 BaO 0.00 0.00 0.04 0.04 0.03 0.02

Na2O 0.16 0.18 0.07 0.02 0.08 0.05

K2O 0.20 0.16 0.16 0.09 0.42 0.30 F 0.73 0.16 1.80 0.44 1.53 0.72 Cl 0.03 0.01 0.04 0.01 0.07 0.02 O = F 0.31 0.07 0.02 0.01 0.42 0.27 O = Cl 0.01 0.00 0.41 0.10 0.14 0.25

H2O 3.48 3.31 2.91 Total 78.67 2.75 87.06 2.84 86.01 7.01

Tetrahedral site Si 3.66 3.50 3.81 Aliv 0.34 0.50 0.19 Octahedral site Alvi 1.93 1.95 0.88 Ti 0.00 0.00 0.00 Fe 0.05 0.15 1.45 Mn 0.00 0.00 0.00 Mg 0.06 0.04 0.12 Interlayer site Ca 0.14 0.12 0.17 Na 0.02 0.01 0.01 K 0.02 0.02 0.04 Ba 0.00 0.00 0.00 Anions OH* 1.82 1.59 1.59 F 0.18 0.41 0.40 Cl 0.00 0.00 0.01 Total 8.22 8.29 8.67

54 Table 3.2. Major and minor element composition (EMPA) and stoichiometry of ferric F-illite from Isivilla (10-Is-30B), Tantamaco (10-Ta-32), and Nuevo Corani (10-NC-2).

Sample ID Is-30B  10-Ta-32  10-NC-2 

SiO2 44.75 1.16 43.44 0.46 44.68 1.92

Al2O3 24.56 1.11 22.85 0.23 22.86 1.00

TiO2 0.19 0.08 0.31 0.06 0.23 0.06 FeO 9.21 0.75 12.84 0.27 12.47 0.73 MnO 0.81 0.06 1.07 0.03 0.45 0.03 MgO 0.22 0.17 0.37 0.07 0.30 0.09 CaO 0.21 0.17 0.06 0.08 0.24 0.14 BaO 0.01 0.02 0.02 0.03 0.04 0.04

Na2O 0.37 0.06 0.39 0.05 0.32 0.11

K2O 9.01 0.85 9.63 0.11 9.20 0.24 F 7.75 0.64 8.20 0.49 8.63 0.54 Cl 0.01 0.01 0.06 0.00 0.04 0.01 O = F 3.26 0.27 2.12 0.02 0.24 0.03 O = Cl 0.00 0.00 0.66 0.11 1.84 0.12

H2O 0.37 0.09 0.00 Total 94.21 2.13 96.55 0.88 97.38 0.95

Tetrahedral site Si 3.32 3.26 3.32 Aliv 0.68 0.74 0.68 Octahedral site Alvi 1.47 1.28 1.33 Ti 0.01 0.02 0.01 Fe 0.57 0.81 0.78 Mn 0.05 0.07 0.03 Mg 0.02 0.04 0.03 Interlayer site Ca 0.02 0.00 0.02 Na 0.05 0.06 0.05 K 0.85 0.92 0.87 Ba 0.00 0.00 0.00 Anions OH* 0.18 0.05 0.00 F 1.82 1.95 2.03 Cl 0.00 0.01 0.01 Total 9.04 9.21 9.16

55 Table 3.3. REE concentrations of the Macusani rhyolites from Tantamaco (10-Ta-1, 10-Ta-8), Calvario Real (10-Cr- 4), Isivilla (10-Is-5) and Nuevo Corani (10-NC-5, 10-NC-14, 10-NC-26) (present study, analysed by ICP-MS), with data from Pichavant et al. (1988b) for whole-rock rhyolites (MN3-330) and. Macusanite glass (JV1)

La Ce Nd Sm Eu Gd Dy Er Yb Total

10-Ta-1 2 5 3 1 0 1 1 0 - 13 10-Ta-8 3 7 3 - - - 0 - - 13 10-CR-4 2 6 3 1 - 1 0 - - 13 10-Is-5 2 7 4 1 - 1 1 - - 15 10-Is-30 4 13 5 1 - 1 1 - 0 24 10-NC-5 5 13 6 1 0 1 1 0 - 28 10-NC-14 6 15 7 2 0 1 1 - - 32 10-NC-26 8 22 8 1 - 1 - - - 41 Cha-7 6 16 9 2 0 1 1 0 0 37 MH3 15 31 14 3 1 2 2 1 1 70 MH4 13 29 14 3 0 2 2 1 1 65 MH5 15 31 14 3 0 3 2 1 1 70 MH6 13 32 13 3 0 3 2 1 1 69 MH7 19 40 19 4 1 - 2 1 1 86 MH8 18 - 16 3 17 - 2 1 57 323 ------0 324 18 38 17 4 1 4 2 1 1 86 325 25 57 23 6 1 4 3 1 1 119 326 ------0 327 17 39 17 5 1 3 3 1 1 86 330 ------0 JV1 2 5 - 1 0 1 1 0 0 10

56 Chapter 4. Uranium mineralization of the Macusani District

4.1. Introduction

The U mineralization of the Macusani district occurs mainly as meta-autunite, with subordinate, but locally predominant, weeksite, in the form of open stockworks and largely contiguous disseminations (Figs. 4.1A, B; 4.2A,B). It is hosted almost entirely by the Macusani

Formation rhyolites, but very locally occurs in coarse interflow clastic sediments along the eastern margin of the volcanic field.

4.2. Distribution of U mineralization

4.2.1. Areal distribution and scale of U mineralization

More than thirteen U occurrences are known on the Quenamari Meseta (Fig. 1.6), most located close to its eastern and north-eastern margins. The most economically promising Kihitian

Complex, which includes the Chilcuno Chico, Quebrada Blanca, Tuturumani and Tantamaco centres, is located at the eastern margin of the meseta, on the lip of the Río Macusani- Río San

Gabán valley. The measured and indicated resource of this cluster of prospects is 47.7 Mt at a grade of 261 ppm U3O8, and a cut-off grade of 75 ppm U, and comprising 27.4 Mlbs U3O8.

(Table 4.1). The measured and indicated resources of the second largest complex, Colibri II/III and Tuturumani, located about 5 km to the west, are 27.9 Mt at 240 ppm U3O8 , representing in

14.7 Mlbs U3O8. The isolated Corachapi deposit at the northern margin of the meseta contains

11.6 Mt at 195 ppm U3O8 , or 5.0 Mlbs U3O8. The Isivilla group includes the Isivilla, Calvario

Real, Puncopata and Calvario I deposits, with a measured and indicated resource of 4.6 Mt at

57 350 ppm U3O8, or 3.5 Mlbs U3O8. Finally, the Corani Group, including the Calvario II, Calvario

III (Calvario Real in Fig. 1.6 inludes both Calvario II and Calvario III), Nuevo Corani and

Amariza) prospects, hosts 3.4 Mt at 166 ppm U3O8, and 1.3 Mlbs U3O8 (Foreman, 2012; Young and Nupen, 2013; Henkle and Associates, 2014). In total, therefore, the drilled prospects host measured and indicated resources of 95.2 Mlbs U3O8.

4.2.2. Stratigraphic distribution of U mineralization

Most previous studies (e.g., Arribas and Figueroa, 1985; Valencia and Arroyo, 1985) have stated that the U mineralization occurs predominantly in the upper units of the rhyolitic

Macusani Formation. However, deep drilling at the largest prospect, Kihitian, has revealed high- grade (1.80% U3O8) mineralization up to 100m below the bed of the Rio Macusani, hosted by 10

Ma flows (Drill hole PT-CH4-V: Foreman, 2012; Young and Nupen, 2013; Henkle and

Associates, 2014). In the sector studied in detail herein, i.e., the Nuevo Corani prospect, the lowest rhyolites, i.e. unit A (Chapter 3) are barren. Southward extension of the stratigraphic relationships documented in that area indicates that unit A corresponds to the 10 Ma eruptive cycle (Cheilletz at al., 1992), suggesting that the mineralizing fluids penetrated to greater depth in the Kihitian sector that further north.

Unit B rhyolites host U mineralization in subvertical and subhorizontal fractures, as well as in disseminated form. The most notable subhorizontal fractures are up to 100 m in length and

0.5 to 5 cm wide and filled with meta-autunite in association with Fe and Mn oxide mineraloids.

Such occurrences include the Pinocho and Chilcuno projects at an elevation of approximately

4350 m a.s.l.. Disseminated U mineralization is observed both in the vicinity of the mineralized fractures and independently, as in the Tantamaco area. Disseminated U mineralization is also observed at the base of unit B, near the contact with the basement rocks at the Tantamaco

58 occurrence (Chapter 3, Fig. 3.3A). The rhyolites in the vicinity of U mineralization are rich in smoky quartz phenocrysts, which can be used as a guide to disseminated U mineralization. Unit

C mineralization is hosted in subvertical and subhorizontal fractures, as well as in disseminated form. Subvertical fractures occur as evenly-spaced, parallel features. Small (<1mm), yellow prismatic crystals of meta-autunite form crusts and, in association with black Mn-mineraloids, cover the surfaces of the subvertical fractures. However, not all of the latter contain meta- autunite, some being entirely unoccupied or covered by flakes of sericite, white and red clays, or

Mn-mineraloids.

4.3. Mineralogy and geochemistry of the U mineralization

Several previous descriptions of the U mineralization in the Macusani area (e.g., Arribas and Figueroa, 1985; Valencia and Arroyo, 1985) documented both uraninite and pseudomorphs of gummite after uraninite. Thus, Arribas and Figueroa (1985) specifically described pitchblende from one occurrence, Pinocho, occurring as botryoidal aggregates altered to yellow gummite and autunite. In order to assess these observations, in this study the blackish phases intimately associated with meta-autunite (Fig. 4.3A) at the Pinocho, Colibri II, Nuevo Corani and Chilcuno occurrences were studied by optical microscopy, XRD, SEM and EMPA. The phases in question appear grey in plane-polarized reflected light and dark-grey or opaque in transmitted light, and

XRD scans indicate that they are amorphous, while SEM and EMPA data reveal that they are either Mn-rich or Fe-rich, and that U is present in, at most, low concentrations.

The black phases associated with meta-autunite and weeksite at the Colibri II and Nuevo

Corani prospects are Mn-rich (MnO 45.02-60.18 wt. %), hydrous oxides, containing variable

SiO2 (0.62-16.38 wt.%), Al2O3 (3.43-9.18 wt.%), K2O (2.19-3.32 wt. %) and CaO (1.75-1.92

59 wt.%), and minor Na2O, MgO, P2O5, FeO, TiO2 and SrO (Table 4.2). Low total values reflect high contents of H2O. Due to the wide range of chemical compositions and the poor crystallinity, the phase is not ascribed a specific mineralogical name.

In contrast to the Mn-mineraloids at the Colibri II and Nuevo Corani prospects, the black botryoidal aggregates at Pinocho are amorphous Fe-Si phases. EMPA analysis of a black phase, occurring in close association with meta-autunite, shows high FeO (58.35 wt.%) and SiO2 (20.58 wt.%) contents, with Al2O3 (1.84 wt.%), P2O5 (1.51 wt.%) and CaO (1.11 wt.%). The Fe phase contains minor amounts (<0.25 wt.%) of Na2O, MgO, MnO, TiO2, SrO and BaO (See Appendix

B for details). Uranium is present in small amounts (average UO3 for sample Pi-1 is 0.40 wt.%, n=11; Table 4.2.). Small (100-300 μm) platy crystals of meta-autunite are observed within the Fe phase (Fig. 4.3B). Meta-autunite occurs in close association with Mn-mineraloids and Fe-Si phases at a number of showings, including the mineralized subhorizontal fractures at Pinocho and Chilcuno, which have Fe-Si oxide selvages. Mn-mineraloids in association with meta- autunite cover the surfaces of fractures at the Colibri II and Nuevo Corani projects. Sulphides such as pyrite (“melnikovite”), previously described by Arribas and Figueroa (1985), were not found.

The present study shows that U mineralization of the Macusani deposits predominantly consists of meta-autunite (Ca[(UO2)(PO4)]2(H2O)6-8), with weeksite a persistent minor phase.

The subhorizontal fractures (Chilcuno, Pinocho occurrences) host predominantly meta-autunite, while subvertical fractures contain both meta-autunite and weeksite (Colibri II and Calvario Real occurrences).

60 Previous research also recorded the presence of torbernite, phosphyuranylite, uranophane, coffinite, billietite and becquerelite (Arribas and Figueroa, 1985), as well as renardite (Valencia and Arroyo; 1985), but these minerals were not confirmed in the present study.

4.3.1. Meta-autunite

Autunite and meta-autunite belong to a group of uranyl phosphate minerals (autunite and meta-autunite group), with the general formula (A[(UO2)(PO4)]2(H2O)n), where A is Ca, K or

Na, and n varies from 12 to 6, depending on the temperature and humidity. Under ambient conditions, meta-autunite, containing 6-8 water molecules, is a stable phase (Sowder et al., 2000;

Suzuki et al., 2005). Autunite and meta-autunite can be distinguished by XRD analysis by the difference in the basal spacing (Suzuki et al., 2005). The XRD patterns of the Macusani samples are consistent with meta-autunite (e.g., Fig. 4.4), characterised by a basal spacing of 8.32 Å.

Petrographic study showed that meta-autunite, in the form of yellow and orange, fine- grained masses, as well as prismatic and platy crystals, forms veins (Figs. 4.5A,B). Meta- autunite also fills voids (Figs. 4.6A,B) in the rhyolites, forms rims around crystals of sanidine and biotite and replaces phenocrysts of magmatic apatite (Fig. 4.7) and monazite. Although extensively searched for, no fluid inclusions were observed in meta-autunite.

Meta-autunite occurs in association with Mn- and Fe- mineraloids (Fig. 4.8A), weeksite

(Fig. 4.8B) and, in one occurrence (Nuevo Corani), with moraesite (Fig. 4.9). Moraesite,

Be2(PO4)(OH)4(H2O), was also confirmed from the Tantamaco and Isivilla (Fig. 4.10), prospects, where, however, it is not associated with meta-autunite. Moraesite occurs as a white clay-like mineral filling small (<1 cm) veins and covering the surfaces of fractures. Identification of moraesite was challenging due to the limitations of the microprobe and SEM techniques that cannot detect light elements like Be. However, small amounts of the mineral were separated by

61 hand-picking and X-ray analysis confirmed the identification (Fig. 4.10). SEM study shows that moraesite fills fractures in the rhyolites (Fig. 4.11 A, B).

Meta-autunite samples were analysed by both EMPA and, to broaden the sample coverage and provide information on Be and other light-elements not readily detected by EPMA,

ICP-MS methods (see Chapter 2 for details of analytical procedures). Averaged compositions derived from several EMPA analyses are presented in Table 4.3, and Table 4.4 provides formula units calculated from these data. For sample Pinocho-1 (Fig. 4.12), the full EMPA data are presented in Table 4.5, whereas for the rest of the samples they are presented in Appendix C. The

ICP-MS data for major and minor elements are presented in Table 4.6, and Table 4.7 provides formula units calculated from these data. Table 4.8 provides minor and trace element concentrations determined by ICP-MS method.

To represent the overall variation in meta-autunite compositions (EMPA results), a triangular CaO-UO3-P2O5 diagram was used (Fig. 4.13). Meta-autunite from different prospects all show some variation in major element chemistry and water contents and are slightly U- enriched, but generally plot close to the ideal meta-autunite composition.

Most of the meta-autunite compositions obtained by ICP-MS are obvious outlliers. In particular, most unusually high or low values of UO3 and Fe2O3 were obtained using this method

(Table 4.6.). It is likely that traces of Mn- and Fe- mineraloids, occurring in close association with meta-autunite, could have been leached by HNO3 during sample preparation. The samples were analyzed by XRD prior to ICP-MS analysis to avoid contamination (see Chapter 2 for details), but this would not detect amorphous phases. Therefore, ICP-MS data may record the overall chemistry of the composite vein material, not specifically that of meta-autunite.

62 The EMPA results are less variable then those for ICP-MS, and more consistent with published EMPA and wet-chemistry analyses of meta-autunite (Volborth, 1959; Abd El-Naby and Dawood, 2008; Lazic et al., 2009). Thus, values from EMPA vary from 62.49 to 65.16 wt.% for UO3, from 4.17 to 5.44 wt.% for CaO and from 15.01 to 16.98 wt.% for P2O5. For comparison, meta-autunite from the Daybreak mine, Washington (Volborth, 1959), is characterized by 63.92 wt. % UO3, 5.16 wt. % CaO and 15.54 wt.% P2O5, whereas that from the

Cer Mountain, Serbia (Lazic et al., 2009) contains 56.63 wt. % UO3, 5.54 wt.% CaO and 16.77 wt.% P2O5. The significant minor elements include Al (0.10-0.85 wt.% Al2O3), K (0.04-1.25 wt.% K2O), Fe (0.07-0.59 wt.% Fe2O3) and Sr (Table 4.3 SrO determined by EMPA for one sample, Pi-1: 0.89 wt.%). The totals of element oxides vary from 84.77 to 89.32 wt.%, evidence for various degrees of dehydration of the meta-autunite samples.

EMPA also provides information on compositional variations within single grains of meta-autunite. Thus, for the sample Pinocho-1, five spots were analyzed (Fig. 4.12; Table 4.5.).

The values for a single crystal 300 μm long range from 61.18 to 68.30 wt.% for UO3, from 4.23 to 6.04 wt.% for CaO, and from 14.72 to 16.77 wt.% for P2O5. Significant variations in water content are observed within single meta-autunite grains (estimated from total oxide values that vary from 86.19 to 92.58 wt.%)

Sample Pi-2 from Pinocho yielded unusually high Fe2O3 contents of 7.61 wt.%, which is probably caused by contamination of the meta-autunite by Fe-mineraloids that occur in close association. Samples Pi-2, Chi-6-1 and Clb-2-1 are characterized by high Be contents of 3785,

3137 and 1977 ppm, respectively (Table 4.8). However, it is impossible to determine if the Be is in the structure of meta-autunite or also records contamination. Petrographic study provides

63 evidence that meta-autunite may occur in close association with moraesite, e.g., these minerals are juxtaposed in a core sample from the Nuevo Corani prospect.

ICP-MS analysis of sample Chi-6-1 from the Chilcuno prospect shows an exceptional

UO3 content of 76.08 wt. %, 10-15 wt.% higher than that of the meta-autunites from the other localities (Table 4.6, Fig. 4.13). Valencia and Arroyo (1985) report phases containing such high amounts of U and interpret them as uraninite. However, the yellow appearance of the sample and its XRD pattern (Fig. 4.4) are not consistent with uraninite. Sample Chi-6-1 is also characterized by low P2O5 (3.41 wt.%) and CaO (1.87 wt.%), as well as high K2O (4.98 wt.%) and Al2O3 (2.64 wt.%) contents. Low P2O5 and high K2O may indicate weeksite ((K2(UO2)2(Si5O13)(H2O)4) contamination of the analysed sample. Another possibility is the presence of U-enriched meta- autunite, similar to those described by Abd El-Naby and Dawood (2008) from the Eastern Desert of Egypt containing up to 67.57 wt. % UO3, low P2O5 (8.12-12.59 wt.%) and CaO (5.57-9.30 wt.

%), as well as high K2O (1.03-1.60 wt.%) and SiO2 (0.80-1.60 wt.%), comparable to those of sample Chi-6-1. Abd El-Naby and Dawood (2008) suggested that the elevated U content of

2+ meta-autunite is caused by (UO2) replacement for Ca, resulting in the release of P into solution.

Meta-autunite samples from all of the Macusani localities contain variable, but significant, amounts of Al2O3 (0.10-3.46 wt.%), SiO2 (0.01-2.01 wt.%), SrO (0.16- 1.43 wt.%),

K2O (0.04-4.98 wt.%) and BaO (0.04-0.83 wt.%) (EMPA and ICP-MS data, Tables 4.3, 4.6).

Strontium, Ba, K and Ba, as well as Rb, substitute for Ca in the interlayer space of the meta- autunite structure. Meta-autunite from the only other economically significant occurrence, the

Daybreak mine, Mount Spokane Area, USA, is also characterized by a high SrO content of 1.38 wt.%. (Volborth, 1959).

64 Macusani meta-autunites are characterised by exceptionally high Al2O3 contents (up to

3.46 wt.%; for comparison, that of the Eastern Desert meta-autunite does not exceed 0.05 wt.%) and high As (up to 4184 ppm). Both Al and As, as well as Si, may occupy the P site in the meta- autunite structure because they form similar bonds

The ThO2 contents of the meta-autunite samples do not exceed 0.49 wt.%. Such low contents are consistent with an oxidizing ore-forming fluid, whereby U is leached from the source, transported and precipitated, whereas Th tends to remain with solid phases. The PbO contents of meta-autunites range from 0.00 to 0.06 wt.%, indicative of the young age of the

Macusani mineralization, with only minor Pb produced from U decay.

Macusani meta-autunite samples are characterized by total REE contents ranging from 69 ppm for the Pinocho project to 804 ppm for the Chilcuno project (Table 4.8, ICP-MS data). The chondrite-normalized REE patterns of the meta-autunites from Isivilla, Tuturumani, Nuevo

Corani, Chilcuno, Colibri II and Pinocho are similar, with pronounced negative Eu and Ce anomalies, and are slightly heavy REE-enriched relative to light REE (Fig. 4.14).

4.3.1. Weeksite

Weeksite ((K2(UO2)2(Si5O13)(H2O)4), in association with meta-autunite, forms veins in rhyolites (Figs. 4.5B, 4.8B). Two samples, from Calvario Real and Colibri II, were analysed by

EMPA (Table 4.8), revealing 48.69-51.33 wt.% UO3, 28.36-29.47 wt.% SiO2, 3.05-4.61 wt.%

K2O, 0.81-0.86 wt.% CaO, 0.77-2.03 Al2O3 wt.% and 0.78-0.91 P2O5 wt.%. The formula units calculated from the EMPA data are also presented in Table 4.9.The Macusani weeksite is characterized by unusually high Al2O3 and P2O5 contents but is otherwise similar to that from the

Anderson mine, Arizona (Jackson and Burns, 2001; Fejfarova et al., 2012), which contains 58.36 wt.% UO3, 29.93 wt.% SiO, 4.85 wt.% K2O, 3.72 wt.% BaO and 0.67 wt.% CaO. The high

65 apparent P2O5 content of the Macusani weeksite (e.g., sample Clb-2-1) may indicate intimate intergrowth with meta-autunite (Fig. 4.8B).

4.4. Conclusions

Meta-autunite is established as the main ore mineral of the Macusani U deposits, occurring in fractures and in disseminated form at all of the studied prospects (Calvario Real,

Chapi, Chilcuno, Colibri II, Isivilla, Nuevo Corani, Pinocho, Tantamaco, Amariza and

Tuturumani), whereas pitchblende was not observed at any of these localities. In particular, the botryoidal pseudomorphs of gummite after pitchblende previously described by Arribas and

Figueroa (1985) from the Pinocho occurrence were not confirmed. The botryoidal aggregates from Pinocho are Fe-Si mineraloids, whereas black crusts associated with meta-autunite at

Colibri II and Nuevo Corani are Mn-mineraloids. In the presence of disseminated meta-autunite, these dark assemblages would be radioactive, have the appearance of pitchblende and potentially have bulk chemical compositions similar to that of pitchblende. The field and mineralogical observations of the present study are, however, in agreement with the conclusions of Herrera and

Rosado (1984) and Rivera et al. (2011) that the main ore mineral is meta-autunite and that uraninite or its alteration products are absent or rare. Uraninite or secondary minerals may be present in very minor amounts in the district, but the most important mineralization is, if not exclusively, of meta-autunite, in association with weeksite, Mn- and Fe-hydroxides and, apparently locally, moraesite.

66

A 2 cm

rhyolites

U mineralization rhyolites

Pinocho 50 cm

B 30 cm

Mn-mineraloids

U mineralization Colibri II

Figure 4.1. Field photographs of U mineralization: A. Meta-autunite in a subhorizontal fracture with Fe-Si oxide selvages (black in the photo), uppermost sub-unit of the Macusani Formation, Pinocho occurrence. B. Subvertical fracture covered with meta-autunite and weeksite in association with Mn-mineraloids, uppermost sub-unit of the Macusani Formation, Colibri II occurrence. Meta-autunite and weeksite cannot be distinguished megascopically.

67 A 2 cm Disseminated meta-autunite

Meta-autunite

Clb-2

B

5 cm Meta-autunite

Mac-206

Figure 4.2. Surface hand samples of U mineralization: A. Sample Clb-2, meta-autunite in fracture and in disseminated form in Macusani rhyolite, Colibri II prospect. B. Sample Mac-206, meta-autunite in veinlet (0.5-1 cm) in rhyolite, Tantamaco prospect.

68 A 2 cm Meta-autunite Mn-mineraloids

Colibri II

B

M-aut

Pi-3

Figure 4.3. Mn-Fe mineraloids: A. Clb-1 surface sample, showing aggregates of black Mn-mineraloids and yellow meta-autunite crystals (small yellow patches), Colibri II prospect. B. Back-scattered electron image of Mn-Fe mineraloids (dark-grey) enclosing prismatic meta-autunite (M-aut) crystals, surface sample, Pinocho prospect.

69

Figure 4.4. Representative X-ray powder diffraction patterns (Cu radiation) of ore samples 10-Is-17 and 10-Is-19 (Isivilla), Pi-1 (Pinocho) and Chi-6-1 (Chilcuno), showing peaks of meta-autunite (M-aut), plagioclase (Pl), and unidentified mica (Mc).

70 A

M-aut

Qz Qz

Mac-206

B

Wkst

M-aut

Mac -206206

Figure 4.5. Microscopic images of U mineralization, Macusani district, Tantamaco prospect, surface sample. A. Plane-polarized transmitted light image of meta-autunite filling vein. B. Cross-polarized transmitted light image of meta-autunite (yellow) and weeksite (blue) filling vein.

71 A Sa

M-aut Qz Sa

Mac-206 Qz 500 μm

B Qz

Qz

M-aut

Bt

50 μm Mac-206

Figure 4.6. Back-scattered electron (BSE) images of U mineralization, Macusani district, Tantamaco prospect, surface sample. A. Meta-autunite fills a void adjacent to an unaltered sanidine phenocryst in rhyolite. B. Meta- autunite filling a void in rhyolite.

72

Qz

Sa

M-aut

Ap

Qz Sa

Mac-206 50 μm

Figure 4.7. Back-scattered electron (BSE) images of U mineralization, Macusani district, Tantamaco prospect, surface sample. Meta-autunite partially replaces an apatite phenocryst and fills a contiguous void in the rhyolite.

73 A San

Mn

M-aut

Mac-202

B

M-aut

M-aut

Clb-2-1

Figure 4.8. Back-scattered electron (BSE) images of U mineralization, Macusani district. A. Meta-autunite (white) and Mn-mineraloids (Mn, grey) fill a fracture in rhyolite. Nuevo Corani prospect, surface sample. B. Meta-autunite (white) and weeksite (dark-grey area in middle of photo) fill a fracture in the rhyolite. Colibri II prospect, surface sample.

74

M-aut

moraesite

NC-3

Figure 4.9. Cross-polarized transmitted light microscopic image of moraesite (blue) and meta-autunite (yellow). Sample NC-3, Nuevo Corani prospect, drill-hole NC01-06-08, 32.6 m.

75

Figure 4.10. Representative X-ray diffraction powder pattern of the 10-Is-30wc sample, drill-hole Ma-Is-Mi-DDH- 2010-03, 43.5 m, Isivilla prospect, showing peaks of moraesite (Mrst) and plagioclase (Pl).

76

A Sa

Moraesite

matrix

10-Is-30A

B Sa

Moraesite

10-Is-30A

Figure 4.11. Back-scattered electron images of moraesite, Macusani rhyolite, drill-hole Ma-Is-Mi-DDH-2010-03, 43.5 m, Isivilla prospect A. Moraesite fills a fracture in rhyolite B. Moraesite enclosing unaltered sanidine phenocryst.

77

Figure 4.12. Back-scattered electron (BSE) images of microcrystals of meta-autunite enclosed in Fe-mineraloids (dark-grey). Surface sample, Pinocho prospect. Red spots and numbers show locations of EMPA analyses (Table 4.5.)

78

Figure 4.13. Simplified chemical compositions of the Macusani meta-autunites (from EMPA and ICP-MS data: Tables 4.3 and 4.6) and Eastern Desert meta-autunites (Abd El-Naby and Dawood, 2008) presented on a triangular diagram. Red star represents stoichiometric meta-autunite with 7 water molecules.

79 REE patterns of the Macusani meta-autunites

Figure 4.14. Chondrite-normalized (Taylor and McLennan, 1985) REE patterns for meta-autunites from the Macusani area (ICP-MS data fromTable 4.8).

80 Table 4.1. Resources of the Quenamari Meseta, at a cut-off grade of 75 ppm U (Foreman, 2012; Young and Nupen, 2013; Henkle and Associates, 2014).

Resources Measured + Indicated Inferred

Complex/Deposit Tonnage, Mt Grade, ppm Tonnage, Mt Grade, ppm U3O8

U3O8 Kihitian 47.7 261 83.6 273

Isivilla 4.6 350 16.1 293

Corani 3.4 166 6.1 131

Colibri II/III and 27.9 240 20.4 170 Tuturumani

Corachapi 11.6 195 3.8 230

Total 95.2 248 130.0 251

Table 4.2. Chemical composition in wt.%. of Mn-mineraloids from Colibri II and Nuevo Corani and Fe-mineraloid from Pinocho (EMPA data); na- not analysed.

Occurrence Colibri II Nuevo Corani Pinocho Sample ID Clb-2-1 Mac 202 Pi-1 n=10 ± σ n=28 ± σ n=11 ± σ

Na2O 0.28 0.05 0.30 0.24 0.04 0.04

SiO2 0.62 0.05 16.38 12.83 20.58 5.43 MgO 0.83 0.05 0.46 0.23 0.22 0.11

Al2O3 3.43 0.23 9.18 4.51 1.84 0.75

K2O 2.19 0.09 2.32 0.96 na na

P2O5 0.31 0.01 0.43 0.28 1.51 0.32 CaO 1.75 0.13 1.92 0.40 1.11 0.16 MnO 60.18 0.66 45.02 13.31 0.07 0.05 FeO 0.57 0.24 1.10 0.86 58.35 7.53

TiO2 0.01 0.02 0.07 0.07 0.04 0.03 SrO 0.32 0.09 0.21 0.10 0.02 0.03 BaO na na na na 0.07 0.04

UO3 na na na na 0.40 0.13 Total 70.49 1.62 77.39 33.79 84.25 14.62

81 Table 4.3. Averaged major and minor element compositions (in wt.%) of meta-autunites from the Macusani area. Analysed by EMPA, (*) – analysis by ICP-MS at Queen’s University. Occurrence Calvario Real Colibri II Nuevo Corani Pinocho Tantamaco Tuturumani Sample 10-CR-9  Clb-2-1  Mac-202  Pi-1  Mac-206  Tut-1 

SiO2 0.48 0.57 2.72 1.48 1.14 1.28 0.60 0.49 0.52 0.22 0.50 0.40

Al2O3 0.29 0.35 0.85 0.75 0.38 0.64 0.15 0.14 0.49 0.69 0.10 0.17

K2O 1.25 1.10 0.28 0.14 0.26 0.13 na na 0.05 0.05 0.04 0.02 BaO 0.04 0.05 0.00* na na na 0.28 0.23 0.19* na 0.48* na

ThO2 0.01 0.03 0.01 0.02 0.01 0.01 na na 0.00 0.01 0.02 0.03

UO3 65.16 1.45 62.49 2.98 64.04 3.57 66.43 1.41 64.52 2.11 64.24 1.82 CaO 5.29 0.77 5.44 0.25 4.96 0.64 5.38 0.39 4.17 0.77 4.63 0.18

Na2O 0.08 0.06 0.02 0.02 0.01 0.01 0.02 0.01 0.00 0.00 0.02 0.06 MgO 0.10 0.06 0.02 0.03 0.00 0.01 0.03 0.02 0.01 0.02 0.00 0.00

P2O5 16.98 0.78 15.36 1.05 14.83 2.22 16.08 0.45 15.01 0.81 16.10 0.40 MnO 0.07 0.09 0.02 0.02 0.29 0.24 0.01 0.02 0.01 0.02 0.02 0.02

Fe2O3 0.07 0.09 0.10 0.10 0.05 0.11 0.59 0.41 0.48 0.70 0.13 0.17

TiO2 na na 0.02 0.03 0.04 0.03 0.02 0.03 0.03 0.02 0.02 0.02

Cr2O3 na na 0.01 0.01 0.01 0.02 na na 0.01 0.01 0.02 0.02

V2O5 na na 0.02 0.04 0.00 0.04 na na 0.01 0.03 0.03 0.05 PbO na na 0.03 0.06 0.02 0.03 na na 0.02 0.03 0.05 0.06

SO2 na na 0.01 0.01 0.00 0.01 na na 0.01 0.01 0.01 0.01

Y2O3 na na 0.07 0.05 0.05 0.04 na na 0.23 0.21 0.04 0.05

Tb2O3 na na 0.03 0.05 0.04 0.06 na na 0.02 0.04 0.04 0.06 CuO na na na na na na na na 0.02 0.03 na na SrO na na 0.53* na na na 0.89 0.13 1.31* na 1.69* na Total, wt % 89.32 2.22 84.77 3.48 84.98 5.05 89.87 1.47 85.11 2.03 85.50 1.94

82 Table 4.4. Formula units for meta-autunites from various locations (calculated from data in Table 4.3). Occurrence Calvario Real Colibri II Nuevo Corani Pinocho Tantamaco Tuturumani Sample 10-CR-9 Clb-2-1 Mac-202 Pi-1 Mac-206 Tut-1 Cation Si 0.068 0.382 0.170 0.086 0.078 0.074 Al 0.048 0.141 0.066 0.025 0.088 0.018 Ti 0.000 0.003 0.004 0.002 0.003 0.002 Fe 0.009 0.013 0.007 0.079 0.067 0.017 Mn 0.008 0.003 0.037 0.001 0.002 0.002 Mg 0.021 0.005 0.000 0.006 0.001 0.000 Ca 0.797 0.818 0.791 0.825 0.674 0.733 Na 0.021 0.005 0.001 0.005 0.000 0.006 K 0.224 0.051 0.050 0.000 0.009 0.008 Ba 0.002 0.000 0.000 0.016 0.011 0.028 Sr 0.000 0.043 0.000 0.000 0.000 0.000 Cr 0.000 0.001 0.001 0.000 0.001 0.002 V 0.000 0.002 0.000 0.000 0.001 0.003 U 1.926 1.843 2.003 1.996 2.042 1.994 Th 0.000 0.000 0.000 0.000 0.000 0.001 P 2.022 1.826 1.869 1.948 1.914 2.013 Y 0.000 0.005 0.004 0.000 0.018 0.003 Tb 0.000 0.002 0.002 0.000 0.001 0.002 Total cations 5.146 5.141 5.006 4.988 4.911 4.906

83 Table 4.5. Major element compositions of meta-autunite crystals from a single sample (Pinocho-1, Fig. 4.12), in wt. %, EMPA data. Analysis ID – the numbers stands for the spot number in Fig. 4.12 and the number of each individual analysis. For example Pinocho 4-5 stands for analysis 5 at spot number 4 at Fig. 4.12.

Analysis ID SiO2 Al2O3 MnO BaO UO3 CaO Fe2O3 Na2O P2O5 SrO Total

Pinocho 1-1 0.73 0.25 0 1.1 66.14 5.96 0.31 0.03 16.21 0.75 91.48

Pinocho 1-2 0.37 0.12 0.02 0.52 66.68 5.17 0.25 0.02 16.43 0.79 90.37 Pinocho 1-3 0.91 0.2 0 0.55 65.23 5.58 0.9 0 15.57 0.63 89.57 Pinocho 1-4 0.52 0.17 0 0.4 66.93 5.85 0.51 0.04 15.97 0.86 91.25 Pinocho 1-5 0.86 0.26 0.04 0.39 66.91 5.86 0.5 0 16.25 0.52 91.59

Pinocho 2-1 0.03 0.02 0.04 0.05 66.8 5.31 0.06 0.02 16.77 1.07 90.17 Pinocho 2-2 0 0 0 0.22 67.83 5.31 0.13 0.03 16.33 0.92 90.77 Pinocho 2-3 0 0.01 0 0 65 5.07 0.49 0 16.36 0.62 87.55 Pinocho 2-4 0.02 0 0 0 67.1 5.09 0.32 0 16.26 0.78 89.57 Pinocho 2-5 0.31 0.03 0.05 0.22 66.89 4.23 0.6 0 16.12 0.92 89.37

Pinocho 3-1 0 0 0.03 0.15 66.57 4.88 0.18 0.01 16.51 1.04 89.37 Pinocho 3-2 0.09 0 0 0.23 67.69 5.46 0.35 0 16.43 0.9 91.15 Pinocho 3-3 0.03 0.01 0 0.22 68.3 4.98 0.17 0.02 16.64 0.74 91.11 Pinocho 3-4 0.09 0 0 0 65.17 5.16 0.51 0.02 16.33 0.93 88.21 Pinocho 3-5 0.24 0.04 0 0.04 66.3 5.33 0.8 0 16.49 0.98 90.22

Pinocho 4-1 0.81 0.17 0 0.12 65.83 5.69 0.82 0.05 15.9 0.89 90.28 Pinocho 4-2 0.69 0.12 0 0.09 65.6 5.14 0.76 0 16 0.86 89.26 Pinocho 4-3 0.97 0.11 0 0.24 64.16 4.79 1.44 0.02 15.41 0.93 88.07 Pinocho 4-4 0.28 0.1 0.01 0.06 67.23 5.66 0.22 0.01 16.52 0.94 91.03 Pinocho 4-5 1.36 0.29 0 0.46 65.86 5.21 1.78 0.01 15.47 0.9 91.34

Pinocho 5-1 1.29 0.33 0.06 0.59 61.18 5.55 1.55 0.03 14.72 0.89 86.19 Pinocho 5-2 1.42 0.38 0.02 0.26 65.65 6.04 0.6 0.03 15.72 1.01 91.13 Pinocho 5-3 0.98 0.17 0 0.33 66.27 5.25 0.71 0.03 16.25 1 90.99 Pinocho 5-4 0.84 0.17 0.02 0.29 67.26 5.55 0.38 0.04 16.12 0.95 91.62 Pinocho 5-5 0.65 0.15 0.03 0.38 67.65 5.73 0.52 0.01 16.43 1.03 92.58

84 Table 4.6. Major and minor element compositions (in wt.%) of meta-autunite from the Macusani District, analysed by ICP-MS at Queen’s University.

Project Chilcuno Isivilla Nuevo Corani Nuevo Corani Pinocho Sample name Chi-6-1 Is-2 Mac-207 NC-1 Pi-2

SiO2 0.18 0.07 0.06 0.01 0.07

Al2O3 2.64 1.12 2.41 1.67 3.46

K2O 4.98 0.12 0.19 0.61 0.21 BaO 0.10 0.83 0.29 0.33 0.23

ThO2 0.49 0.36 0.40 0.33 0.39

UO3 76.08 57.10 63.20 53.12 55.88 CaO 1.87 3.36 5.36 3.82 6.90

Na2O 0.18 0.11 0.01 0.08 0.12 MgO 0.06 0.05 0.08 0.07 0.57

P2O5 3.41 14.23 15.65 12.92 16.41 MnO 0.02 0.01 0.01 0.01 0.01

Fe2O3 0.09 0.21 0.76 0.46 7.61

TiO2 0.00 0.01 0.02 0.01 0.02

Cr2O3 DL DL 0.00 DL 0.00

V2O5 0.00 DL 0.00 0.00 0.00 PbO 0.06 0.03 0.03 0.03 0.04

SO2 na na na na na

Y2O3 0.02 0.03 0.04 0.15 0.02

Tb2O3 0.00 0.00 0.00 0.00 DL CuO 0.00 0.00 0.01 0.00 0.00 SrO 0.16 1.40 1.43 1.36 0.96 Total, wt % 90.34 79.03 89.94 74.98 92.89

85 Table 4.7. Formula units for meta-autunites (calculated from the data in Table 4.6).

Occurrence Chilcuno Isivilla Nuevo Corani Nuevo Corani Pinocho

Sample Chi-6-1 Is-2 Mac-207 NC-1 Pi-2

Cation

Si 0.032 0.012 0.008 0.001 0.010

Al 0.564 0.215 0.400 0.338 0.575

Ti 0.000 0.001 0.002 0.001 0.002

Fe 0.015 0.031 0.099 0.073 0.000*

Mn 0.003 0.001 0.001 0.001 0.001

Mg 0.017 0.011 0.017 0.018 0.120

Ca 0.364 0.587 0.809 0.701 1.044

Na 0.062 0.035 0.004 0.025 0.034

K 1.153 0.024 0.034 0.133 0.037

Ba 0.007 0.053 0.016 0.022 0.013

Sr 0.017 0.132 0.117 0.135 0.000

Cr 0.000 0.000 0.000 0.000 0.000

V 0.000 0.000 0.000 0.000 0.000

U 2.902 1.955 1.870 1.910 1.657

Th 0.020 0.013 0.013 0.013 0.013

P 0.524 1.964 1.866 1.872 1.961

Y 0.002 0.002 0.003 0.014 0.002

Tb 0.000 0.000 0.000 0.000 0.000

Total cations 5.683 5.038 5.257 5.259 5.467

“*”- Fe was excluded from the formula units calculations for sample Pi-2, as the extremely high Fe2O3 content (7.61 wt.%) is probably caused by contamination of the sample by Fe-oxides.

86 Table 4.8. Minor and trace element concentrations (in ppm) of meta-autunites from the Macusani district (ICP-MS data).

Location Pinocho Chilcuno Isivilla Nuevo Corani Tantamaco Colibri II Sample ID Pi-2 Chi-6-1 Is-2 Mac-207 Mac-206 Clb-2-1

As 1496 194 3581 1718 4184 743 Be 3785 3137 210 235 249 1977 Bi 4 12 24 51 36 9 Ce 11 24 31 13 142 2 Co 29 DL DL DL DL DL Cr 23 DL DL DL 2 DL Cs 75 352 12 28 24 318 Cu 20 17 22 12 94 10 Dy 10 48 DL 53 64 59 Er 9 15 82 92 43 38 Eu 0 6 1 1 5 5 Gd 5 58 25 7 46 42 Ho 2 6 29 17 12 12 La 6 252 54 14 106 189 Li 177 7 10 121 135 6 Lu 2 15 4 39 10 4 Mg 3428 367 301 432 866 314 Mn 68 170 21 161 131 29 Na 923 1314 588 569 263 833 Nb 26 DL 7 3 5 0 Nd 8 237 40 16 176 191 Ni 8 DL 0 10 29 DL

87 Table 4.8. (Continuation) Minor and trace element concentrations (in ppm) of meta-autunites (ICP-MS data)

Location Pinocho Chilcuno Isivilla Nuevo Corani Tantamaco Colibri II Sample ID Pi-2 Chi-6-1 Is-2 Mac-207 Mac-206 Clb-2-1 Pd 7 12 65 55 20 35 Pr 2 61 11 4 41 51 Rb 68 4095 132 139 107 2332 Sb 1 DL 1 DL DL DL Sc DL DL DL DL 2 DL Sm 3 61 16 5 53 50 Sn 12 2 8 4 14 4 Tb DL 9 13 4 9 8 Ti 119 4 20 63 185 19 Tl 13 19 6 2 5 3 Tm 1 2 8 26 8 5 V 20 3 DL 4 5 2 W 8 DL 764 4 10 DL Y 170 178 1384 1220 615 540 Yb 10 11 32 267 71 32 Zn 469 119 87 108 257 131 Zr 2 DL 2 1 DL DL Total: 11026 10822 7600 5533 8056 7999

DL - below detection limit. Au, B, Cd, Hf, Hg, Mo, Pt, Re, S, Se and Te concentrations were all below detection limits.

88 Table 4.9. Weeksite from Calvario Real and Colibri II prospects: Major element composition (in wt.%) and formula units. Analysed by EMPA.

Occurrence Calvario Real Colibri II Sample ID 10-Cr-9 Clb-2-1 n=25 ± σ n=7 ± σ

K2O 4.61 0.39 3.05 0.43 BaO 0.35 0.09 na na CaO 0.86 0.06 0.81 0.08

Na2O 0.22 0.06 0.15 0.02

UO3 51.33 1.36 48.69 2.41

ThO2 0.03 0.04 na na

SiO2 29.47 0.57 28.36 1.16

Al2O3 0.77 0.11 2.03 0.82 MgO 0.04 0.03 na na

Fe2O3 0.05 0.06 0.05 0.03 MnO 0.02 0.03 na na

P2O5 0.91 0.09 0.78 0.08 Total 88.66 83.92 Cations Si 5.660 5.632 Al 0.174 0.476 Fe 0.010 0.010 Mn 0.003 0.000 Mg 0.012 0.000 Ca 0.176 0.173 Na 0.083 0.058 K 1.130 0.774 Ba 0.027 0.000 U 2.071 2.032 Th 0.001 0.000 P 0.148 0.131 Total cations 9.495 9.286

n- number of analysis; na – not analysed, σ – standart deviation

89 Chapter 5. U-Th-Pa geochronology of U mineralization

5.1. Introduction

Herrera and Rosado (1984) described meta-autunite, the main U mineral of the Macusani deposits, as a secondary mineral, which formed “muy reciente”, i.e., very recently. However, no geochronological data were provided in support of this model.

In the present research, an attempt was initially made to date the U mineralization using the U-Pb method (Li et al., 2012). The 206Pb/238U ratios of the meta-autunite samples vary from

0.00008 to 0.00016 and the 207Pb/235U ratios from 0.00084 to 0.00684 for (Appendix E). Such small ratios indicate a lack of radiogenic Pb in the system and hence the very young age of the samples. Thus, the apparent age from the 206Pb/238U system varies from 0.35 to 1.06 Ma.

However, the common Pb attains 52% of the total Pb, which implies that 207Pb/206Pb and

207Pb/235U ages are subject to large errors and, therefore, ambiguous.

However, U-series geochronology, specifically the 238U/230Th and 235U/231Pa methods that use two separate decay schemes based on two isotopes of U, is well suited for dating the deposits. These methods cover time intervals of 600 ka and 250 ka, respectively, and their combination provides an opportunity to assess the accuracy of apparent dates. Whereas use of U- series methods has traditionally been limited by complex sample preparation that involved dissolution of the sample and spiking, recent studies (Eggins et al., 2005) show that in situ

238U/230Th dating can be successfully performed on a variety of materials using laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS).

90 This study employs LA-ICP-MS to obtain both 238U/230Th and 235U/231Pa ages on U ore samples from the Quenamari Meseta and to compare the ages to past major geological and climatic events, thereby refining the ore formation model.

5.2. Samples selected for geochronology

Seven samples of meta-autunite from outcrops at the Colibri II, Tantamaco, Tuturumani,

Nuevo Corani, Chilcuno and Pinocho prospects were selected for U-series geochronology (Table

5.1; Fig. 5.1.). Samples Chi-6 and Pi-2 were collected from subhorizontal mineralized fractures and the others from subvertical fractures. The samples fron Colibri II prospect comprised intergrown meta-autunite and weeksite.

Prior to analysis, the U minerals were verified (Fig. 5.2) by X-ray powder diffraction analysis using a Panalytical X’pert Pro diffractometer, using Cu K-alpha radiation (30 kV accelerating voltage, 15 mA operating current). SEM study showed that weeksite occurs in close association with meta-autunite in sample Clb-2-1 (Fig. 4.8B), the textural relationships indicating that both minerals formed roughly at the same. Samples of U minerals in veins (Chi-6, Pi-2 and

Clb-2) were cleaned of debris and flat surfaces, obtained by splitting of the vein, were used for the LA-ICP-MS analysis. Samples Clb-2-1 and Clb-2 were collected from the same location at the Colibri II project and were used to examine the effects of different sample preparation techniques. The details of methodology and data processing are discussed in Chapter 2.

5.3. Age Calculations

The ages of the Macusani samples were calculated assuming initial 230Th and 231Pa to be zero, and 231Th, 234Th and 234Pa to have been in secular equilibrium at the time of meta-autunite

91 formation. The absence of initial 230Th and 231Pa is a basic assumption for the U-Th-Pa geochronology method and is based on the geochemical characteristics of these elements. Under oxidizing conditions, U is leached from the rocks and transported, whereas Th and Pa have low solubilities and tend to remain with residual solid phases (Edwards et al., 2003).

The following basic age equations were used:

(1) 231Pa/235U age equation

and (2) 230Th/238U age equation

where: (1) ratios in square brackets are activity ratios defined as ai= λiNi (λi is the decay constant

-λ238t -λ235t and Ni the number of atoms for nuclide I); (2) λi – λ238 = λi; λi - λ235 = λi; e = e =1, where

λi is the decay constant for nuclide i and t is time; and (3) the decay constants are λ230 = 9.1577

-6 -6 -5 ×10 ; λ234 = 2.8263 ×10 , λ231 = 2. 115 ×10 , as determined by Cheng et al. (1998).

The advantage of using the combined 238U/230Th and 235U/231Pa methods is that this provides an opportunity to assess the validity of the apparent ages. The degree of agreement between U-Th and U-Pa apparent ages can be assessed in a concordia diagram, in which the ordinate axis of the diagram represents the calculated 231Pa/235U activity ratio and the abscissa the calculated 230Th/234U activity ratio. The concordia line, analogous to that in the U-Pb method, represents the activities for which 231Pa and 230Th ages are in agreement.

92 5.4. U-series ages of the Macusani U mineralization

Analyses of U-series isotopes show that for the samples of U minerals from the Macusani area, [234U/238U] activity ratios are near secular equilibrium, e.g. unity (0.8452 to 1.084). The values above unity would traditionally be interpreted as indicating recent addition of U to the sample, whereas values below unity would represent recent loss of U. No significant difference between the isotopic ratios of the centres and margins of veins was detected (Table 5.2).

The calculated apparent U-Th ages of the meta-autunites from the Macusani district show a wide range from 62 ka to 408 ka, while the apparent U-Pa ages range from 19 ka to 174 ka

(Table 5.2). There are fewer U-Pa than U-Th ages because some samples have [231Pa/ 235U] ratios exceeding unity, indicating that 231Pa and 235U are in secular equilibrium and the age of the samples exceeds the upper limit of the U-Pa method (Edwards et al., 2003).

On average, U-Pa ages are younger than those obtained from U-Th dating. The incongruent U-Pa and U-Th ages indicate open-system behaviour, i.e., loss or gain of U, Th and

Pa after meta-autunite formation. The degree of agreement between U-Th and U-Pa apparent ages was assessed on concordia diagrams for each sample (Figs. 5.3-5.9).

Some samples, e.g., Tut-1 and Pi-2 are concordant or near-concordant within error (Figs.

5.3-5.4). Sample Tut-1 has a concordant age of ca. 220 ka and the Pi-2 sample yields concordant ages of ca. 220 ka and 160 ka, both thereafter remaining closed systems. Samples Mac-206 and

Chi-6, displaying no lower intersects with concordia, have upper intersects at 140 ka and 400 ka, respectively (Figs. 5.5, 5.6). Sample Mac-207 has a lower interupt with concordia at ca. 40 ka and an upper intercept at ca. 500 ka (Fig. 5.7).

Sample Clb-2-1 (Fig. 5.8) is near-concordant within error, formed at ca. 110 ka and experienced limited Pa loss thereafter, as recorded in the positions of the points below the

93 concordia line. Sample Clb-2 (Fig. 5.9), collected from the same location as Clb-2-1, is, on the other hand, discordant, with no lower intercept with concordia and an upper intersect at ca. 210 ka. The differing ages reveal that U mineralization in the Colibri II did not form simultaneously, but rather over several episodes. There are several aspects that may have also contributed to the difference in the results. Sample Clb-2-1 is a polished offcut, whereas sample Clb-2 was obtained by splitting a meta-autunite vein. Offcut samples have some advantages over natural flat surface samples, e.g., smoother relief of the ablated surface, which may affect the geochronology results. Finally, samples Clb-2-1 and Clb-2 contain weeksite as a subsidiary phase, but its exact amount in each sample is unknown. The dating of a mineral mixture may be associated with some complications.

The discordance of the analyses is usually attributed to U gain or loss, as U6+ is much more mobile under oxidizing conditions than Th and Pa (Edwards et al., 2003). However, extreme U loss would be required to shift points above the concordia line. Uranium gain in meta- autunite, which contains ca. 60 wt.% UO3, is unlikely as this would require an increase in U content of ca. 50%, especially for some samples (Mac-207, Chi-6 and Clb-2). Therefore, loss or gain of Th and Pa is considered the most likely process to have occurred in the Macusani meta- autunites.

If Th and Pa are gained or lost in the same ratio as they existed in the mineral, the analyses will define a discordia that intercepts the origin. If, however, the gained or lost Th and

Pa have a ratio different from that of the original mineral, the discordia will not intersect the origin. Thus, samples Clb-2 and Mac-206 have no lower intercept with concordia and illustrate loss or gain of Th and Pa with ratios much lower than those in the original mineral, despite the similar chemistries of these elements. Samples Mac-207 and Chi-6, exhibiting lower intercepts

94 with concordia, may have also lost Th and Pa in ratios different from those originally in the mineral. Therefore, the ages obtained from the lower intercepts with concordia are ambiguous.

The ages obtained from the upper intercept with concordia, on the other hand, are not affected by the ratios of lost Th and Pa, as long as this ratio is the same for all measured points of the sample. The upper intercept ages, therefore, are more reliable. Samples Chi-6 and Mac-207 most likely represent loss of Th and Pa with the same ratio, so that their upper intercept ages are valid.

5.5. Discussion

The U-series ratios obtained for the U minerals of the Macusani district are applicable for

U-Th and U-Pa geochronology. The concordia diagrams reveal that open-system behavior prevailed for most of the meta-autunite samples and, therefore, reliable ages are determined only for concordant samples and those with discordia with upper intercepts with concordia. The plotted points suggest Th and Pa gain and loss, rather than U gain or loss after initial mineral formation. No systematic differences in isotopic ratios and ages between the margins and centres of the meta-autunite veins were noted.

The samples provided averaged U-Th ages at 69 ka (Clb-2-1), 130 ka (Pi-2) and 314-317 ka (Pi-2 and Tut-1), and probably reliable upper intercepts of ca. 103-113 ka (Mac-206), 210 ka

(Clb-2) and 400 ka (Chi-6). These ages are much younger that the last recorded magmatic activity in the Macusani area at 6.8 Ma (Cheilletz et al., 1992), demonstrating that meta-autunite formation was not directly related to magmatic processes. The obtained ages are also younger than the last glacial maximum in the Central Andes at 1.8 Ma (Clapperton; 1983), a period when glaciers, including mountain ice-caps, covered a much greater area of the Eastern Cordillera than at any subsequent period. Clapperton suggested that the Central Andes experienced as many as

95 four major subsequent episodes of glaciation at 170-140 ka, 80-30 ka, 30-16 ka and 16 -10 ka.

The U-Th ages of meta-autunite at the Colibri II (69-79ka, Clb-2-1 sample) and Pinocho (130 ka) prospect coincide with two of these periods, whereas ages of the meta-autunite from other localities coincide with interglacial periods. This would imply that meta-autunite precipitation was not restricted to interglacial periods characterized by wet and warm climates (Stroup et al.,

2014), when sufficient water could have been released to transport and deposit U, but was, in part, coincident with glacial periods as well. However, it should be emphasized that there are no radiometric age constraints on glacial advances or retreats in the region prior to 12 ka (Mercer et al., 1977) and the tentative glaciate chronology of the area is based on largely Northern

Hemispheric data.

Samples from different prospects have different U-Th ages (Fig. 5.10) and, in addition to a range of ages for U mineralization over the entire Macusani area, ages obtained for individual samples also show significant variability. For example, samples from the same Colibri II location

(Clb-2 and Clb-2-1) gave differing U-Th ages of 69 ka and 210 ka, whereas analysis of the Pi-2 sample from Pinocho shows two distinct ages at 130 ka and 317 ka. The range of ages indicates that meta-autunite was not deposited in a single event over the entire Quenamari Meseta, but rather in a series of episodes.

The variability in ages for individual samples, in combination with the evidence of open- system behaviour apparent from some analyses, and the locations of the majority of ore bodies on the walls of active fluvial canyons suggest that U ore precipitation, although apparently episodic and related to major climatic factors, is an ongoing process. Thus, even slight local changes in the water circulation regime could result in meta-autunite precipitation. Ice cores from the Quelccaya Ice Cap indicate significant variations in precipitation over relatively short

96 intervals of time. For example, at least four periods of excess precipitation (>20% of the annual mean) are recorded in the ice cores during the past 1500 years (Thompson et al., 1985). Although similar episodes have not been identified in detail for the past 400 ka, they would certainly effect

U movement in the system and contribute to U mineral precipitation.

Formation of meta-autunite mineralization in the Macusani area shares a number of characteristics with U mineralization in the Murray Basin, Australia, where highly fractionated,

U-enriched, S-type Lake Boga granites host torbernite, meta-natroautunite and saleeite in fractures (Birch et al., 2011). The U-Th apparent ages for U-phosphates from the Murray basin range from 505 ka to 115 ka and, as in the Macusani area, only generally correlate with interglacial periods.

5.6. Conclusions

For the first time, LA-ICP-MS analysis was successfully used to obtain both U-Th and U-

Pa apparent ages of meta-autunite samples. The U-Th geochronology indicates that U ore of the

Quenamari Meseta was deposited in a series of episodes between ca. 69 and 500 ka. These results confirm the previous U-Pb studies that show that the apparent ages of the Macusani meta- autunites are younger than 1 Ma (Li et al., 2012) and are much younger than the last magmatic activity in the Macusani area, which took place at 6.8 Ma (Cheilletz et al., 1992). Thus, the U-Th geochronology indicates that U ore-formation of the Macusani was unambiguously related to

Quaternary, low-temperature, surficial processes.

97 Chi-6 Clb-2 2.5c m Pi-2

Samples Pi-2 Pinocho prospect Chi-6 Chilcuno prospect Clb-2 Colibri II prospect Clb-2-1 Colibri II prospect Mac-206 Tantamaco prospect Clb-2-1 Mac-206

Figure 5.1. Representative samples selected for geochronological analysis. Samples Pi-2, Chi-6 and Clb-2 were obtained by splitting meta-autunite veins longitudinally. Samples Clb-2-1 and Mac-206 are polished cutoffs of meta-autunite veins in rhyolite. Most samples are meta-autunites, but samples Clb-2 and Clb-2-1 are meta-autunite with subordimate weeksite. Note that samples Mac-207 (Nuevo Corani prospect) and Tut-1 (Tuturumani prospect) used in the study are not shown. More information about the samples is presented in Table 5.1.

98

Figure 5.2. X-ray powder diffraction patterns (Cu radiation) of selected samples used in the geochronology study, showing peaks of meta-autunite (M-aut), weeksite (Wkt), and unidentified mica (Mc).

99 1.6 Tut-1, Tuturumani

1.4

1.2

300ka U 250ka 150ka 200ka 1 120ka 235 100ka 80ka Pa/ 0.8

231 50ka Age ca. 220ka 0.6

0.4 20ka

0.2

0 0 0.2 0.4 0.6 0.8 1 1.2 230Th/234U

Figure 5.3. Concordia [231Pa/235U] – [230Th/234U] activity ratio diagram and U-Th-Pa age for the Tut-1 sample, from the Tuturumani prospect. The squares represent individual analyses with error margins.

100 1.2 Pi-2, Pinocho

200ka 250ka 300ka 150ka 1 120ka 100ka 80ka 0.8 Ages ca.160ka

U 50ka ca. 220ka 235

0.6

Pa/ 231 0.4 20ka 0.2

0 0 0.2 0.4 0.6 0.8 1 1.2 230Th/234U

Figure 5.4. Concordia [231Pa/235U] – [230Th/234U] activity ratio diagram and U-Th-Pa ages for the Pi-2 sample, from the Pinocho prospect. The squares represent individual analyses with error margins.

101 3 Mac-206, Tantamaco

2.5

U Age 2

235 ca. 140ka Pa/

1.5 231

250ka 300ka 100ka 150ka 200ka 1 50ka 0.5

0 0 0.2 0.4 0.6 0.8 1 1.2 230Th/234U

Figure 5.5. Concordia [231Pa/235U] – [230Th/234U] activity ratio diagram and estimated U-Th-Pa age for the Mac-206 sample, from the Tantamaco prospect. The squares represent individual analyses with error margins.

102 Chi-6, Chilcuno 1.2

200ka 250ka 300ka 150ka 1 120ka 100ka 80ka 0.8 Age

ca. 400ka

U 50ka 235

0.6

Pa/ 231 0.4 20ka

0.2

0 0 0.2 0.4 0.6 0.8 1 1.2 230Th/234U

Figure 5.6. Concordia [231Pa/235U] – [230Th/234U] activity ratio diagram and estimated U-Th-Pa age for the Chi-6 sample, from the Chilcuno prospect. The squares represent individual analyses with error margins.

103

1.2 Mac-207, Nuevo Corani

200ka 250ka 300ka 150ka 1 120ka 100ka 80ka

0.8 Age

U >500ka

50ka 235

0.6

Pa/ 231 0.4 20ka

0.2

0 0 0.2 0.4 0.6 0.8 1 1.2 230Th/234U

Figure 5.7. Concordia [231Pa/235U] – [230Th/234U] activity ratio diagram and estimated U-Th-Pa age for the Mac-207 sample, from the Nuevo Corani prospect. The squares represent individual analyses with error margins.

104

1.2 Clb-2-1

200ka 250ka 300ka 150ka 1 120ka 100ka

80ka

U 0.8 Age

235 ca.110ka 50ka

Pa/ 0.6 231

0.4 20ka 0.2

0 0 0.2 0.4 0.6 0.8 1 1.2 230Th/234U

Figure 5.8. Concordia [231Pa/235U] – [230Th/234U] activity ratio diagram and estimated U-Th-Pa age for Clb-2-1 sample, from the Colibri II prospect. The squares represent individual analyses with error margins.

105

1.2 Clb-2, Colibri II

200ka 250ka 300ka 150ka 1 120ka 100ka Age 80ka

0.8 ca. 210ka

U 50ka 235

0.6

Pa/ 231 0.4 20ka 0.2

0 0 0.2 0.4 0.6 0.8 1 1.2 230Th/234U

Figure 5.9. Concordia [231Pa/235U] – [230Th/234U] activity ratio diagram and estimated U-Th-Pa age for the Clb-2 sample, from the Colibri II prospect. The squares represent individual analyses with error margins.

106

Figure 5.10. Location of several uranium occurrences in the Quenamari Meseta with determined U-Th ages (average U-Th ages from Table 5.2).

107 Table 5.1. Samples selected for geochronological analysis. SVF denotes subvertical mineralized fractures and SHF subhorizontal mineralized fractures. Flat surfaces of the samples obtained by splitting the meta-autunite veins.

Elevation Style of Mineral Sample Sample Prospect (m) mineralization composition preparation Mac-206 Tantamaco 4383 SHF meta-autunite offcut Nuevo Mac-207 4505 SVF meta-autunite offcut Corani

meta-autunite Clb-2-1 Colibri II 4517 SVF offcut and weeksite

meta-autunite Clb-2 Colibri II 4517 SVF flat surface and weeksite

Chi-6 Chilcuno 4390 SHF meta-autunite flat surface flat surface Pi-2 Pinocho 4351 SHF meta-autunite

Tut-1 Tuturumani 4383 SHF meta-autunite flat surface

108 Table 5.2. U-series activity ratios and apparent U-Pa and U-Th ages for meta-autunite samples from the Macusani U occurrences.

[234U/238U] [234U/238U] [230Th/238U] [230Th/238U] [230Th/234U] [230Th/234U] [230Th/234U] [231Pa/235U] [231Pa/235U] [231Pa/235U] Sample Ratio Error Ratio Error Ratio Error Age (ka) Ratio Error Age (ka) Mac-206, Tantamaco MAC 206-1 edge 0.968 0.002 0.55 0.00 0.57 0.00 92 0.73 0.01 61 MAC 206-2 center 0.948 0.002 0.50 0.00 0.53 0.00 82 0.71 0.02 59 MAC 206-3 edge 0.973 0.001 0.54 0.01 0.56 0.01 88 0.71 0.01 58 MAC 206-3 edge 0.964 0.007 0.62 0.01 0.64 0.01 111 0.77 0.01 69 MAC 206-4 center 0.980 0.003 0.50 0.01 0.51 0.01 78 1.17 0.22 NS MAC 206-5 edge 1.013 0.009 0.57 0.01 0.56 0.01 90 0.70 0.06 56 MAC 206-6 center 1.041 0.016 0.64 0.02 0.63 0.02 109 0.70 0.09 56 MAC 207-6 center 0.971 0.002 0.58 0.00 0.60 0.00 99 0.70 0.03 57 MAC 206-7 center 0.973 0.002 0.94 0.04 0.97 0.04 373 2.62 0.21 NS MAC 206-8 edge 0.955 0.004 0.54 0.01 0.57 0.01 91 0.58 0.05 41 MAC 206-9 edge 0.965 0.001 0.57 0.01 0.59 0.01 95 0.72 0.03 60 MAC 206-10 edge 0.956 0.002 0.58 0.01 0.61 0.02 101 0.59 0.12 41

Mac -207, Nuevo Corani MAC 207-1 edge 0.950 0.002 0.51 0.00 0.54 0.01 84 0.68 0.02 53 MAC 207-2 edge 0.946 0.003 0.52 0.01 0.55 0.01 87 0.69 0.03 55 MAC 207-3 edge 0.948 0.003 0.53 0.00 0.56 0.00 89 0.70 0.01 56 MAC 207-4 center 0.946 0.005 0.58 0.00 0.62 0.01 104 0.71 0.01 58 MAC 207-4a center 0.895 0.002 0.73 0.00 0.82 0.00 184 0.82 0.01 80 MAC 207-7 edge 0.968 0.001 0.60 0.01 0.61 0.01 104 0.69 0.07 55 MAC207-7 edge 0.936 0.006 0.96 0.01 1.03 0.01 NS 0.96 0.05 151 MAC 207-8 0.918 0.004 0.90 0.00 0.97 0.00 398 0.86 0.01 92 MAC 207-9 0.903 0.004 0.84 0.00 0.93 0.00 290 0.87 0.01 97 MAC 207-12 0.888 0.002 0.85 0.01 0.96 0.01 340 0.90 0.01 107

109 Table 5.2. (cont.).

[234U/238U] [234U/238U] [230Th/238U] [230Th/238U] [230Th/234U] [230Th/234U] [230Th/234U] [231Pa/235U] [231Pa/235U] [231Pa/235U] Sample Ratio Error Ratio Error Ratio Error Age (ka) Ratio Error Age (ka) Pi-2, Pinocho Pi 2-1 0.927 0.010 0.66 0.02 0.72 0.01 137 0.63 0.20 46 Pi 2-2 0.987 0.014 0.68 0.03 0.68 0.03 125 0.75 0.14 65 Pi 2-3 0.973 0.013 0.68 0.01 0.70 0.01 132 0.87 0.08 94 Pi 2-4 0.975 0.037 0.68 0.03 0.69 0.01 128 0.89 0.02 104 Pi2-5 1.046 0.029 0.69 0.01 0.67 0.02 120 0.76 0.13 66 Pi 2-6 0.945 0.016 0.66 0.01 0.70 0.02 130 0.86 0.13 93 Pi 2-7 0.926 0.015 0.66 0.01 0.71 0.01 134 0.55 0.25 37 Pi 2-8 0.920 0.004 0.65 0.01 0.70 0.01 132 0.83 0.05 82 Pin 2-3 0.933 0.013 0.87 0.01 0.92 0.02 277 0.87 0.02 94 Pin 2-4 0.955 0.007 0.89 0.01 0.93 0.02 287 0.96 0.03 147 Pin 2-8 0.931 0.005 0.89 0.02 0.95 0.02 331 0.94 0.04 132 Pin 2-9 0.942 0.006 0.89 0.02 0.95 0.02 336 0.84 0.05 85 Pin 2-11 0.948 0.012 0.91 0.01 0.96 0.02 352 0.91 0.02 111

Tut-4, Tuturumani Tut 4-1 0.945 0.008 0.86 0.01 0.92 0.01 278 1.01 0.03 NS Tut 4-2 0.919 0.004 0.87 0.01 0.94 0.01 304 0.94 0.03 132 Tut 4-3 0.918 0.005 0.89 0.01 0.98 0.01 408 0.95 0.03 138 Tut 4-4 0.921 0.003 0.85 0.01 0.93 0.01 282 1.03 0.04 NS Tut 4-5 0.915 0.003 0.87 0.01 0.94 0.01 310 0.94 0.04 132 Tut 4-6 0.914 0.004 0.88 0.01 0.98 0.01 401 0.98 0.04 174 Tut 4-7 0.917 0.004 0.86 0.01 0.93 0.01 293 1.03 0.04 NS Tut 4-8 0.914 0.003 0.86 0.01 0.94 0.01 305 0.95 0.02 140 Tut 4-9 0.919 0.003 0.86 0.01 0.94 0.01 305 1.01 0.04 NS Tu 4-10 0.939 0.007 0.86 0.01 0.92 0.02 278 1.33 0.07 NS Tut 4-11 0.927 0.004 0.86 0.01 0.93 0.01 287 1.15 0.07 NS

110 Table 5.2. (cont.).

[234U/238U] [234U/238U] [230Th/238U] [230Th/238U] [230Th/234U] [230Th/234U] [230Th/234U] [231Pa/235U] [231Pa/235U] [231Pa/235U] Sample Ratio Error Ratio Error Ratio Error Age (ka) Ratio Error Age (ka) Clb-2, Colibri II clb 2-2 0.943 0.036 0.45 0.02 0.48 0.02 72 0.43 0.07 26 clb 2-4 0.909 0.016 0.47 0.02 0.52 0.02 81 0.38 0.14 22 clb 2-5 0.975 0.004 0.72 0.02 0.74 0.02 145 0.83 0.09 83 clb 2-6 0.964 0.006 0.69 0.02 0.71 0.02 135 0.92 0.06 117 clb 2-7 0.952 0.011 0.68 0.01 0.71 0.01 135 0.71 0.19 58 clb 2-8 0.947 0.008 0.73 0.01 0.77 0.01 161 0.73 0.05 61 clb 2-9 1.010 0.026 0.68 0.02 0.71 0.04 134 0.80 0.10 76

Clb-2-1, Colibri II clb 21-1 edge 0.865 0.012 0.38 0.02 0.45 0.02 64 0.61 0.08 44 clb 21-2 edge 0.943 0.008 0.44 0.02 0.47 0.02 68 0.33 0.40 19 clb 21-3 edge 0.946 0.008 0.47 0.02 0.50 0.01 75 0.58 0.16 41 clb 21-4 edge 0.928 0.008 0.40 0.01 0.44 0.01 62 0.58 0.09 41 clb 21-5 edge 0.958 0.007 0.47 0.02 0.50 0.02 74 0.37 0.21 21 clb 21-6 center 0.924 0.009 0.43 0.03 0.47 0.03 68 0.42 0.25 26 clb 21-7 center 0.923 0.005 0.47 0.02 0.51 0.02 77 0.60 0.06 43 clb 21-8 center 0.906 0.009 0.42 0.02 0.47 0.03 68 0.53 0.22 35 clb21-9 center 0.852 0.015 0.37 0.03 0.43 0.04 62 0.61 0.03 44 clb 21-10 center 0.910 0.006 0.44 0.02 0.49 0.02 72 0.64 0.07 48

111 Table 5.2. (cont.).

[234U/238U] [234U/238U] [230Th/238U] [230Th/238U] [230Th/234U] [230Th/234U] [230Th/234U] [231Pa/235U] [231Pa/235U] [231Pa/235U] Sample Ratio Error Ratio Error Ratio Error Age (ka) Ratio Error Age (ka) Chi-6, Chilcuno Chilcuno 1 1.084 0.023 1.01 0.02 0.97 0.01 394 0.94 0.01 132 Chilcuno2 0.931 0.006 0.75 0.02 0.79 0.03 170 0.82 0.12 80 Chilcuno3 0.931 0.006 0.75 0.02 0.79 0.03 170 0.84 0.12 86 Chilcuno 5 0.932 0.011 0.83 0.02 0.89 0.02 239 0.90 0.07 109 Chilcuno 6 0.918 0.004 0.83 0.01 0.91 0.01 257 0.85 0.04 89 Chilcuno 6-6 0.909 0.003 0.52 0.01 0.58 0.01 93 0.56 0.15 38 Chilcuno6-8 0.969 0.002 0.56 0.01 0.58 0.01 93 0.58 0.14 40 Chilcuno 6-9 0.977 0.013 0.57 0.01 0.58 0.01 95 0.67 0.02 52 Chilcuno 6-11 0.963 0.006 0.51 0.01 0.53 0.01 81 0.55 0.11 38 Chilcuno 7 0.933 0.013 0.79 0.02 0.84 0.02 200 0.86 0.06 91 Chilcuno 8 0.932 0.008 0.78 0.03 0.84 0.05 198 0.78 0.05 72 Chilcuno10 0.924 0.004 0.83 0.01 0.89 0.02 243 0.86 0.01 91 Chilcuno 11 0.932 0.005 0.78 0.02 0.84 0.02 199 0.83 0.02 82 Chilcuno12 0.938 0.007 0.79 0.02 0.85 0.03 206 0.80 0.08 76 Chilcuno13 0.965 0.005 0.72 0.02 0.75 0.02 150 0.82 0.03 80

“edge” and “centre” refer to the position of the analysed point in the meta-autunite vein.

112 Chapter 6. Stable isotope composition of the ore-forming fluid

6.1. Introduction

Light-stable isotope techniques have not been previously documented for U6+ minerals, and the present study is the first attempt to apply these techniques to, specifically, meta-autunite.

The isotopic composition of the mineral is closely related to the structure and type of bonds represented therein (Hoefs, 2004). Meta-autunite (Ca[(UO2)(PO4)]2(H2O)6-8) is composed of uranyl-phosphate sheets, with cations and water in the interlayer spaces. There are strong

3- 6- internal bonds in the PO4 tetrahedra and UO6 square bipyramids, as well as relatively weak external bonds between uranyl-phosphate sheets and cations, and extremely weak bonds between uranyl-phosphate sheets and H2O groups (Locock and Burns, 2003). This structure bears some similarities to those of clay minerals, in particular smectites, which have layers composed of Si- tetrahedra and Al-octahedra, with exchangeable cations and H2O groups occupying the interlayer space. Light-stable isotopic studies of meta-autunite, therefore, are likely to be associated with the difficulties typical for clay minerals, such as large surface area and presence of interlayer water, which rapidly exchange isotopes with atmospheric and meteoric waters (Hoefs, 2004).

Despite this, Sheppard and Gilg (1996) show that clay minerals are often out of isotopic equilibrium with local surface water, implying that some information on past environments and, by analogy, may be recorded in meta-autunite.

113 6.2. Parameters and assumptions used in fluid composition calculation

Knowledge of both the isotope fractionation factors between a mineral and water and the temperature at which the mineral formed is required in order to calculate the isotopic composition of the fluid. The O isotope fractionation factor determined for smectite-water by

Savin and Lee (1988) and the H isotope fractionation factor for smectite-water of Capuano

(1992) were used herein as proxies for the fractionation between meta-autunite and water, as smectite has types of bonds similar to those in meta-autunite.

The O isotope fractionation factor for meta-autunite was also calculated using a

“modified increment” method proposed by Zheng (1991; 1993). This method is based on the correlation observed between the bond strengths in the mineral and the degree of 18O-enrichment of the mineral relative to quartz. The increment method allows for quantification of the 18O- enrichment of the mineral by calculating the oxygen isotope index (I-18O) of the mineral in question (min) relative to the reference mineral (ref). The I-18O index is defined as:

18 3/2 3/2 I- Omin= (M16/M18) ref/2n0(M16/M18) min ct-0 ×V,

where V is the oxidation state of the cation in question, nct and no are the numbers of cations and

16 18 O per formula, M16 and M18 are the atomic weight of the molecules with O and O,

18 18 respectively, and i’ct-o is the O-increment normalized to the O-increment of the Si-O bond:

i’ct-o=ict-o/isi-o

114 18 The I- O increment is a function of cation-oxygen bond strength (cct-o), which depends on the cation oxidation state (V) and coordination number of the cation (CNct) and corresponding ionic radii of cation and O (rct+ro):

cct-o = V/ (rct+ro)CNct

The I-18O increment is also a function of the effect of cation mass on the isotopic substitution

(Wct-o), which is defined as:

Wct-o=(mct+m16/mct+m18)×(m18/m16)

16 Where mct is the atomic weight of the cation, and m16 and m18 are the atomic weight of O and

18O, respectively.

The strongly-bonded cations in meta-autunite contribute more to the total I-18O index than the weakly-bonded cations (Zheng, 1993). The weight of the contribution is reflected by a parameter q, which is defined by:

q = Vk, k=-1, 0, +1.

3- where k = -1 is assumed for strongly-bonded cations, such as those in the complex anions PO4

6- 2+ and UO6 , and k = +1 is assumed for weakly-bonded complex anions (e.g., Ca ).

115 The influence of H2O groups was not considered in these calculations, as the contribution of these weak bonds is small, and a significant amount of the interlayer water is lost during the preheating of the samples.

Calculations for meta-autunite were carried out for the uranyl-phosphate sheet, per 12 O; the other parameters are listed in Table 6.1. The calculated I-18O index for meta-autunite equals

0.9078, which gives a fractionation factor for O of 1000lnα=3.55×(106/T2)+15.77. This curve is nearly identical to that of the empirical smectite-water oxygen curve of Savin and Lee (1988):

(Fig. 6.1.).

The temperature of meta-autunite formation in the Macusani district has not been precisely established. However, LA-ICP-MS U-Th-Pa geochronology of meta-autunite samples from the Quenamari Meseta confirm the young age of U mineralization (Chapter 5). Macusani meta-autunites formed after 500 ka, a long time after the last magmatic activity in the area, which took place 6.8 Ma ago (Cheilletz et al., 1992). Thus, U ore-formation was related to

Quaternary, most likely low-temperature, surficial processes.

As Quaternary paleoclimate data on the Macusani area are limited, the estimation of the temperature may be associated with large uncertainties. The present-day average temperature for the Macusani area varies from 10C for the coldest month of June to 26C for the hottest months of October and December. The isotopic composition of the ore-forming fluid was calculated for a temperature of 15C , the average annual present-day surface temperature for the Macusani region (http://www.worldweatheronline.com/Macusani-weather-averages/Puno/PE.aspx).

However, based on the monthly average temperatures, the temperature for the fluid calculation is estimated with error of ± 5-10C.

116 6.3. Isotope composition of the meta-autunites and the ore-forming fluid

Stable isotopic compositions of meta-autunites range from 5.2 ‰ to 14.7 ‰ for δ18O and from -141 ‰ to -83 ‰ for δ2H (Table 6.2). The wide range of δ2H values is related to the fact that, of all elements, hydrogen exhibits the largest variations in stable isotope ratios due to the largest mass difference relative to the mass of the element between two stable isotopes – 1H and

2H (Hoefs, 2004). Additionally, the range of δ18O and δ2H values may reflect inability to remove the interlayer water completely during the sample preparation. For hydrogen isotope analysis, samples of meta-autunite are heated to 1000 C to remove surface-adsorbed water, but this also causes loss of some, but not all, interlayer water (Sowder et al., 2000; Suzuki et al., 2005). For oxygen isotope analysis, samples of meta-autunite are heated to 1300 C, which causes an almost complete water loss from the interlayer space. However, high gas yields after the O extraction

(100% and more, see Chapter 2 for details) reveal survived interlayer water. Due to various degrees of dehydration of the meta-autunite samples during sample preparation, the precision of the H- and O-isotope analysis of meta-autunite requires careful interpretation of the isotopic variation.

The composition of the fluid calculated using smectite-water O and H fractionation factors as proxies for autunite-water fractionation (Fig. 6.2.) ranges from -21.7‰ to -12.2‰ for

δ18O and from -181‰ to -123‰ for δ2H. The composition of the fluid calculated using the incremental fractionation factor for 15C ranges from -21.8 ‰ to -12.3 ‰ for δ18O (Table 6.2.), which is very close to the compositions established using the smectite-water fractionation factor, and for that reason was not separately plotted on Fig.6.2. Most of the fluid compositions calculated for 15C plot close to the global meteoric water line and isotopic compositions of the

117 nearby Quelccaya Ice Cap (Thompson and Davis, 2005), the main active water source in the

Macusani area (Fig. 6.2.). Eight of the δ2H values calculated at 15oC are lower than expected but the large variation of isotopic ratios typical for H (Hoefs, 2004) and various degrees of dehydration of the meta-autunite samples would have an impact on the results. The isotope composition of the fluid plotted well below the range of magmatic fluids.

6.4. Conclusions

A temperature of 15C seems the reasonable for the ore-forming fluid, as fluid compositions calculated for this temperature are also in agreement with the environment expected from the geochronology (Chapter 5). This implies a Quaternary, low-temperature process for U ore formation. The calculated δ18O values of the water which formed the meta- autunite vary from -21.7‰ to -12.2‰, which is consistent with formation of meta-autunite from low-temperature meteoric fluids as suggested by Herrera and Rosado (1984).

118

Figure 6.1. Fractionation factors as a function of temperature for δ18O as calculated by the incremental method (-1-) (Zheng, 1991, 1993) and the smectite proxy (-2-) (from Savin and Lee, 1988).

119 Figure 6.2. The isotopic compositions of meta-autunites and of the associated fluids calculated using O and H smectite-water fractionation factors (Savin and Lee, 1988; Capuano, 1992) at 150C, and composition of the fluid calculated using O incremental fractionation factor (data from Table 6.2). * - data for Quelccaya Ice Cap from Thompson and Davis, 2005; ** - data on arc and crustal felsic magmas fluids from Hedenquist and Lowenstern, 1994.

120

18 Table 6.1. Parameters used in the calculation of the I- O index: CNct – coordination number of cation; rct+ro – ionic radii of cation and anion; mct - the atomic weight of the cation; Wct-o – effect of cation mass on the isotopic 18 18 substitution; cct-o – cation-oxygen bonds strength, Ict-o – O-increment; and i’ct-o - the normalized O-increment (Zheng, 1991; 1993).

CNc rst+ro Bond mct Wct-o Cct-o Ict-o I’ct-o t (Å) U6+-O 6 2.13 238.03 1.05651 0.46948 0.02581 1.02049 P5+-O 4 1.55 30.97 1.03878 0.80645 0.03068 1.06070 Ca2+-O 8 2.50 40.08 1.04224 0.10000 0.00414 0.03278

121 Table 6.2. Isotopic compositions of meta-autunites and composition of the fluid calculated from meta-autunites using smectite fractionation factors (Savin and Lee, 1988; Capuano, 1992) for 150C,; Fluid* - δ18O values of the fluid obtained using a fractionation factor calculated by the incremental method for 150C.

Fluid*, Sample Location Meta-autunite Fluid, t=150C t=150C 18 2 18 2 18 δ O δ H δ Of δ Hf δ Of* Chi-5 Chilcuno 11.2 -129 -15.7 -169 -15.8 Chi-6-1 Chilcuno 10.0 -92 -16.9 -132 -17.0 Chi-6-2 Chilcuno 5.2 -99 -21.7 -139 -21.8 Chi-6-3 Chilcuno 11.4 -87 -15.5 -128 -15.6 Chi-6-4 Chilcuno 8.7 -91 -18.1 -131 -18.2 Chi-6-5 Chilcuno 9.6 -86 -17.3 -126 -17.4 Clb-2-1 Colibri II 6.8 -98 -20.1 -138 -20.2 Clb-2-3 Colibri II 8.7 -103 -18.2 -143 -18.3 Clb-2-4 Colibri II 8.6 -94 -18.2 -134 -18.3 Clb-2-5 Colibri II 11.4 -97 -15.5 -137 -15.6 10-Is-10 Isivilla 13.2 -116 -13.7 -156 -13.8 10-Is-17 Isivilla 11.8 -123 -15.1 -163 -15.2 10-Is-19 Isivilla 11.1 -123 -15.8 -163 -15.9 Is-2 Isivilla 12.7 -117 -14.2 -157 -14.3 M-206/1 Tantamaco 9.3 -141 -17.6 -181 -17.7 M-206/2 Tantamaco 12.7 -141 -14.2 -181 -14.3 M-206-1 Tantamaco 9.7 -112 -17.2 -152 -17.3 Mac-207-1 Nuevo Corani 11.1 -96 -15.8 -136 -15.9 Mac-207-2 Nuevo Corani 8.1 -101 -18.8 -141 -18.9 Mac-207-3 Nuevo Corani 10.4 -83 -16.5 -123 -16.6 Mac-207-4 Nuevo Corani 9.9 -97 -17.0 -138 -17.1 Mac-207-5 Nuevo Corani 8.7 -96 -18.2 -136 -18.3 NC-1 Nuevo Corani 10.2 -107 -16.7 -148 -16.8 Pi-1 Pinocho 9.3 -138 -17.6 -178 -17.7 PI-2 Pinocho 14.5 -92 -12.4 -132 -12.5 PI-2-2 Pinocho 10.6 -95 -16.3 -135 -16.4 PI-2-3 Pinocho 11.1 -100 -15.8 -140 -15.9 PI-2-4 Pinocho 9.3 -88 -17.6 -128 -17.7 Tut-1 Tuturumani 10.2 -110 -16.7 -150 -16.8 Tut-4-1 Tuturumani 12.4 -100 -14.5 -140 -14.6 Tut-4-2 Tuturumani 10.4 -93 -16.5 -133 -16.6 Tut-4-3 Tuturumani 14.7 -100 -12.2 -140 -12.3 Tut4-4 Tuturumani 10.0 -96 -16.9 -137 -17.0

122 Chapter 7. General Summary and Ore-Formation Model

7.1. Introduction

The significance of the magmatic U enrichment of the Macusani rhyolites to mineralization has been recognized by all previous studies (Herrera and Rosado, 1984; Arribas and Figueroa, 1985; Clark et al., 1990; Leroy and George-Aniel, 1992). However, the mode of transport of the U, i.e., magmatic-hydrothermal versus meteoric fluids, the process of ore formation, and even the mineralogical composition of the ore have remained contentious. The present study provides new data on the mineralogy, geochemistry and geochronology of the

Macusani deposits that permit establishment of a new genetic model.

7.2. Ore mineralogy

The present study shows that meta-autunite is the main ore mineral of the U deposits in the Macusani district and that weeksite is a persistent minor phase. Meta-autunite is observed in fractures and in disseminated form at all of the studied localities (Calvario Real, Chapi,

Chilcuno, Colibri II, Isivilla, Nuevo Corani, Pinocho, Tantamaco and Tuturumani), whereas weeksite was observed at Colibri II and Calvario Real. Meta-autunite also occurs in association with Mn- and Fe- mineraloids and, in one confirmed occurrence, Nuevo Corani, with moraesite.

Pitchblende, however, has not been observed at any of these localities, and, specifically, the botryoidal pseudomorphs of “gummites after pitchblende” described by Arribas and Figueroa

(1985) from the Pinocho occurrence were not confirmed. Instead, X-ray powder diffraction

(XRD) and electron microprobe analysis (EMPA) data indicate that botryoidal aggregates from the Pinocho occurrences are Fe-Si mineraloids, and that black crusts associated with meta-

123 autunite at Colibri II and Nuevo Corani are Mn-mineraloids. In the presence of disseminated meta-autunite, these dark assemblages would be radioactive, have the appearance of pitchblende and could attain bulk chemical compositions approaching that of pitchblende. Specifically, the high UO3 content of one of the samples (Chi-6), similar to that reported by Valencia and Arroyo

(1985), can be attributed to isomorphic substitution in the structure of meta-autunite similar to that reported from the Eastern Desert of Egypt (Abd El-Naby and Dawood, 2008), rather than to pitchblende. The coffinite-pyrite-chalcopyrite associations described by Valencia and Arroyo

(1985) from an unspecified locality on the Quenamari Meseta were also not observed. Instead, the field and mineralogical observations of the present study are in agreement with those of

Herrera and Rosado (1984) and, implicitly, Rivera et al. (2011), i.e., the ore minerals are meta- autunite and weeksite and that uraninite or its alteration products are either rare or absent.

The meta-autunite is characterized by 53.12-76.08 wt.% UO3, 1.87-6.90 wt.% CaO, 3.41-

16.98 wt.% P2O5, 0.10-3.46 wt.% Al2O3, 0.01-2.01 SiO2 wt.%, 0.16- 1.43 wt.% SrO, 0.04-4.98 wt.% K2O and 0.04-0.83 wt.% BaO, a compositional range similar to that of meta-autunites from other localities, e.g., the Eastern Desert of Egypt (Abd El-Naby and Dawood, 2008) and the

Daybreak mine, USA (Volborth, 1959).

7.3. Timing of ore genesis

The U-series ratios obtained for meta-autunites of the Macusani district are applicable for

U-Th and U-Pa geochronology. The samples provided averaged U-Th ages at 69 ka (Clb-2-1),

130 ka (Pi-2) and 314-317 ka (Pi-2 and Tut-1) and probably reliable upper discordia-concordia intercepts of ca. 103-113 ka (Mac-206), 210 ka (Clb-2) and 400 ka (Chi-6). These ages are much younger that the last recorded magmatic activity in the Macusani area at 6.8 Ma (Cheilletz et al.,

124 1992), demonstrating that meta-autunite formation was not directly related to magmatic processes. The obtained ages are also younger than the last glacial maximum in the Central

Andes at 1.8 Ma, but some of the ages, 130 ka of the Pi-2 sample and 69 ka of the Clb-2-1 sample, coincide approximately with subsequent episodes of glaciation at 170-140 ka and 80-30 ka (Clapperton, 1983). However, the meta-autunite ages from other localities coincide with interglacial periods. This would imply that meta-autunite-precipitation was not restricted to interglacial periods characterized by wet and warm climates (Stroup et al., 2014), when sufficient water could readily have been released to transport and deposit U, but was, in part, nearly coincident with glacial periods as well. The U-Th-Pa geochronology unambiguously indicates that U ore-formation of the Macusani was related to Quaternary, low-temperature, surficial processes.

The concordia 231Pa/235U - 230Th/234U diagrams reveal that open-system behavior prevailed for most of the meta-autunite samples. The plotted points (Figs. 5.3- 5.9) suggest Th and Pa gain and loss, rather than U gain or loss after initial mineral formation. The variability in ages for individual samples, in combination with the evidence of open-system behaviour apparent from some analyses, and the locations of the majority of ore bodies on the walls of active fluvial canyons, suggest that U-ore precipitation, although apparently episodic and related to major climatic factors, is probably an ongoing process.

7.4. The source of the U

Arribas and Figueroa (1985) proposed that magmatically-derived, relatively hot brines were the source of U, which precipitated as pitchblende and later was remobilized low- temperature fluids. In contrast, Herrera and Rosado (1984) Leroy and George-Aniel (1992) and

125 Rivera et al. (2011) suggested that U was leached from the Macusani rhyolites by meteoric fluids and precipitated directly as meta-autunite.

The apparent absence of pitchblende in all of the studied U occurrences and drill-holes, as well as the absence of reduced mineral associations (pyrite-chalcopyrite) makes the first hypothesis improbable.

The U content of the Macusani rhyolites is exceptionally high, with an average of 20 ppm in unaltered rocks, and a significant proportion of the U is hosted, not by accessory minerals such as monazite, but by the fine-grained glassy groundmass and the abundant obsidian

(“macusanite”) bodies. The groundmass constitutes about 50 vol. % of the rhyolites and its average U content is 15 ppm (Leroy and Aniel, 1992). According to Cheilletz et al. (1992), the volume of the Macusani Formation is approximately 430 km3, which makes it an enormous potential source of U. Therefore, leaching of the Macusani rhyolites could have readily mobilized sufficient U6+ for the formation of the deposits.

The present study shows that that U-hosting phases, mainly the glassy matrix of the rhyolites and the glass clasts that are also enriched in P are affected by argillic alteration, specifically to illite and minerals of the smectite group. Dissolved apatite phenocrysts, which are likely minor sources of P for meta-autunite, are also observed.

The evidence of the alteration and connection between meta-autunite and rhyolites, as source-rocks for meta-autunite formation, is also recorded in the REE patterns of the phases. All of the rhyolite and meta-autunite samples from Macusani have negative Eu anomalies. The Eu anomaly, formed as a result of magmatic plagioclase fractionation, preserved in altered and unaltered rhyolites and inherited by oxidizing fluid and meta-autunite precipitated therefrom.

Rhyolites from the Tantamaco, Calvario Real, Isivilla and Nuevo Corani and Chapi occurrences

126 are depleted in REE (12-36 ppm) relative to unaltered rhyolites (65 ppm to 120 ppm, Pichavant et al., 1988b), whereas meta-autunite samples from the Macusani area are characterized by high total REE contents (69-804 ppm). The REE may have been released from the glassy matrix of the altered rhyolites, transported by oxidizing fluids and precipitated later in meta-autunite.

Rhyolites from the Tantamaco, Calvario Real, Isivilla, Nuevo Corani and Chapi occurrences have slight positive Ce anomalies, whereas the meta-autunite samples have significant negative

Ce anomalies. Given that tetravalent Ce in oxidizing conditions is less mobile than REE3+(Akagi and Masuda, 1998), formation of a positive Ce anomaly in the altered source and a negative Ce anomaly in the oxidizing fluid and minerals precipitated therefrom are consistent with the rhyolites as a source of the REE and, by analogy, the uranium (Braun et al., 1990; Hidaka et al.,

2005). Although, illite-smectite alteration is not spatially related to the mineralization, it could have promoted the release of U from the glassy matrix of rhyolites over millions of years and therefore have contributed to meta-autunite formation.

7.5. The nature of the ore-forming fluids

The nature of the fluid involved in formation of the U mineralization is reflected in the

REE patterns and isotopic compositions of H and O of the meta-autunites.

Negative Ce anomalies observed in the normalized REE patterns of the meta-autunites are indicative of the oxidizing nature of the ore-forming fluid (Braun et al., 1990; Hidaka et al.,

2005). In addition, the calculated δ18O values of the water which formed the meta-autunite at low temperatures vary from -21.7‰ to -12.2‰, which is consistent with formation of meta-autunite from modern, i.e., high-altitude, low-temperature meteoric fluids, as suggested by Herrera and

Rosado (1984) and Rivera et al. (2011). A modern origin for the fluids is also reflected in the U-

127 Pb, U-Th and U-Pa ages of less than 1 Ma for the mineralization. Most of the fluid compositions calculated for 15C, the average surface temperature in the region, plot close to the global meteoric water line and fall within the isotopic range for the Quelccaya Ice Cap (Thompson and

Davis, 2005). There is no evidence of reducing, high-temperature fluids that would be required for uraninite precipitation, as suggested by Arribas and Figueroa (1985). A.H. Clark

(unpublished data) documented CO2-rich secondary fluid inclusions with homogenization

(minimum) temperatures in the narrow range, 226-285°C, hosted by quartz and apatite phenocrysts from the walls of fractures, but these fluids probably represent an earlier alteration stage (intermediate argilitic alteration) with no unambiguous connection to the mineralization.

Uranium was probably transported in the form of a phosphate complex, the predominant uranyl complex in oxidized natural waters (Langmuir, 1978). No carbonate minerals were found in or around the ore zones, which suggests that the activity of dissolved CO2 was low and that

2- carbonate complexes of U were not significant. Low activities of CO3 decrease the solubility of meta-autunite (Langmuir, 1978), and thus lower the concentrations of U, P and Ca required for its precipitation.

The presence of the moraesite in association with meta-autunite (Nuevo Corani prospect, sample NC-3) indicates that Be was mobile at some stage, or locally, during U ore formation. Be mobility is enhanced in meteoric waters by release of soluble F, which can occur as a result of the weathering of fluorite-rich rocks (Ginzburg and Shatskaya 1964; Novikova 1967; Grigor’yev

1997). The Macusani rhyolites, especially their glass, are enriched in F (1.33 wt.% F in volcanic glass: Pichavant et al., 1988b). Weathering of the Macusani rhyolites could therefore have released considerable F, which could have mobilized Be from the Macusani rhyolites.

128 7.6. The uranium trapping mechanism

The majority of known deposits in the eastern and northeastern part of the Quenamari

Meseta crop out on the upper walls of the largest active fluvial canyons. Thus, the geomorphological environment that is now focusing groundwater flow was the most favourable for the precipitation of meta-autunite ore. Furthermore, the highest-grade deposits (Chilcuno and

Pinocho) are located along the longest-lived valley of the Rio Macusani. Therefore, the location of the mineralization is largely controlled by structures and groundwater flow paths, rather than a specific chemistry of the host rocks. High U concentrations required for meta-autunite precipitation can be achieved by the prolonged, perhaps millions of years, interaction of oxidizing fluids with the U-rich Macusani rhyolites. Although information on high-grade U mineralization at depth in the Kihitian sector is limited and no ore samples from the lower units of the Macusani rhyolites were involved in the present study, it is possible that mixing have occurred between deeper groundwater which had leached U over time and shallower, more recent groundwater.

The solubility of U minerals is also strongly affected by the presence of highly absorbing phases that can induce precipitation even when the solution is undersaturated with a phase

(Dall’aglio et al., 1974; Langmuir, 1978; Sato et al., 1997). Iron and Mn-oxides absorb U onto their surfaces and incorporate microcrystals of U minerals, which can act as nucleation sites for further meta-autunite precipitation (Sato et al., 1997). In the Macusani area, meta-autunite is coeval with Fe- and Mn-mineraloids and occurs in intimate association with them in a number of localities (Pinocho, Chilcuno, Colibri II, Nuevo Corani). The samples of Fe-Si mineraloids from the Pinocho occurrence are characterized by 0.40 wt.% UO3, where U is absorbed by Fe-Si mineraloids, and also contain micro-crystals of meta-autunite (Fig. 4.3). These associations

129 support the contention that the presence of the highly absorbing phases also affected meta- autunite precipitation. For example, the high-grade U occurrences, e.g., Chilcuno and Pinocho, occur as subhorizontal fractures filled by meta-autunite with Fe- and Mn-mineraloids selvages.

Another possible mechanism of U ore precipitation, although minor and local, is precipitation through evaporation of the U-bearing fluid. Thus, weeksite

(K2(UO2)2(Si5O13)(H2O)4), a consistent minor phase in the Macusani U ore, is a uranyl silicate with a U/Si ratio of 2:5. High U/Si ratios required for weeksite precipitation can be achieved by evaporation of U-bearing meteoric fluids (Finch and Murakami, 1999).

7.7. Model of ore formation

Field observations and the mineralogical and geochemical data of the present study support the U ore formation model proposed by Herrera and Rosado (1984), wherein U was leached from the Macusani rhyolites and the U mineralization precipitated as meta-autunite directly from low-temperature, oxidizing meteoric fluids. The alternative ore-formation model proposed by Arribas and Figueroa (1985), Valencia and Arroyo (1985) and Dahlkamp (2010) proposes hydrothermal formation of primary, pitchblende-sulphide mineralization, and subsequent mobilization of U by meteoric waters and precipitation of meta-autunite in fractures.

The apparent absence of such primary U4+ mineralization and directly associated hydrothermal alteration, as well as the absence of geochronological ages approaching those of the recorded magmatic or hydrothermal activity in the area, make the argument for hydrothermal U ore- formation unconvincing.

Based on geological, mineralogical and geochemical factors, as well as the results of geochronological analysis, a more specific ore-formation model can be proposed (Fig. 7.1):

130 (1) The peraluminous rhyolites of the Macusani Formation were produced by partial melting of a crustal metapelite source (Noble et al., 1984; Pichavant et al., 1988b) (Fig. 7.1A). Between 12.3 and 6.8 Ma (Cheilletz et al., 1992), U-rich rhyolites erupted as frothy debris-flows (Sandeman et al., 1995). A minor volume of strongly fractionated melt, represented by volcanic glass, is even further enriched in U, containing up 160 ppm U (H.A. Sandeman and A.H. Clark, unpublished data). .

(2) Late-magmatic hydrothermal greisen-type alteration locally affected the rhyolites, forming topaz-muscovite-quartz associations. This was followed by extensive intermediate-argillic alteration. However, the exact timing of these alteration stages is uncertain, and no U enrichment occurred during either stage.

(3) Episodic tectonic uplift throughout the later Tertiary caused faulting and canyon incision in the area (Fig. 7.1B). The rise of the Andes also promoted glacier formation on the high peaks, including the Quelccaya Ice Cap. The glacial history of the Central Andes incorporates at least five glacial episodes, including the last glacial maximum at 1.8 Ma, as well as four episodes at

140-170 ka, 30-80 ka, 16-30 ka and 10 -16 ka (Clapperton, 1983). Tertiary tectonic uplift of the

Central Andes (Poulsen et al., 2010) and later Quaternary glacial activity triggered an intense morphological and hydrological rejuvenation of the Macusani area.

(4) Alternating glacial and interglacial periods increased erosion and meteoric water circulation along the fracture systems, facilitating the leaching of U from Macusani Formation rhyolites and macusanite and its transport along fractures (Fig. 7.1C). Continuous, relatively slow fluid movement along the subhorizontal fractures may have been a significant factor in the precipitation of U ore. To provide this continuous flow, the elevation of subhorizontal fractures should have coincided with the water table at that time - the largest U occurrences, at Chilcuno

131 and Pinocho, as well as the disseminated U mineralization of the Tantamaco area, share the same elevation, around 4350m a.s.l., which may have marked the past groundwater table in unit B.

(5) Uranium as meta-autunite is precipitated as a primary phase from meteoric water due to mixing of low-temperature fluids, interaction of the fluid with highly absorbing Fe- and Mn- mineraloids, and, to a lesser extent, evaporation under favourable semi-arid climatic conditions.

The main episodes of ore-formation took place at 69 ka, 130 ka, 314-317 ka, and probably at ca.

103-113 ka, 210 ka and 400 ka (Fig. 7.1D). The limited open system behaviour and the position of most known ore bodies on the walls of active fluvial canyons suggest that U mobilization and precipitation, although episodically related to climate factors, may be an ongoing process

7.8. Comparison to other volcanic- and granite-hosted U deposits.

A number of authors have compared the Macusani deposits to other volcanic-hosted or hydrothermal U deposits. Arribas and Figueroa (1985) noted some similarities between the U occurrences of the Macusani area and U deposits of the Hercynian granites of France. Both are hosted by peraluminous magmatic rocks and have a strong connection to primary U-enrichment in the melt. Similarly, Dahlkamp (2010) suggested that the Macusani U mineralization could be compared to the largest known volcanic-hosted deposits at Strelt’sovskoe, Russia, based on the volcanic host rocks and presumed pitchblende-sulphide ore association.

However, the present study reveals a number of critical differences between the

Macusani deposits and other volcanic- or granite-hosted U deposits. As summarized in Table 7.1, these include: (1) The mineralogical composition of the ore is distinct in that U4+ minerals are absent in the Macusani U deposits and meta-autunite is the main U ore mineral; (2) The U mineralization of the Macusani district is much younger than U mineralization of the

132 Streltsovskoe or Dornot deposits and do not coincide with any recoded magmatic or hydrothermal activity in the area.

There are some similarities between the Macusani U deposits and some other volcanic- hosted deposits. As with the deposits at Macusani, the Sierra Peña Blanca deposit (Mexico), the

Spor Mountain Be-U deposit (Utah) and the BaiYangHe deposit (China) involved meteoric waters during the late stages of ore-formation, although the mineral associations in each are distinct (George-Aniel et al. 1991; Lindsey, 1981; Shabaga et al., 2013: Table 7.1).

The only other known economic occurrence of meta-autunite, the Daybreak mine,

Washington, is hosted by granitic plutons of Cretaceous to Tertiary age. The plutons are jointed and range in composition from hornblende granodiorite to quartz monzonite and alaskite and associated pegmatites and aplites. Host rocks within the shear zones of the deposit are affected by intense alteration, including kaolinitization, sericitization and “removal of Fe-oxides”

(Dahlkamp, 2010). Dark green masses and aggregates of meta-autunite fill open fractures in the monzonites and form pods up to 10 cm thick and 1.5 m long at the level of the water-table. Meta- autunite also occurs in thin veins and as disseminations in gouge zones (Volborth, 1959). The

Daybreak mine was a relatively small U deposit that produced about 20 t U at an average grade of 0.25% (Dahlkamp, 2010). Although the host rocks are distinct, the proposed origin of the meta-autunite at the Daybreak mine is similar to that of the Macusani occurrences, wherein leaching of U from the host rocks was by circulating groundwaters, with subsequent precipitation of meta-autunite along a fluctuating water table (Dahlkamp, 2010).

133 7.9. Specific Achievements of this Research

. The main ore U mineral of the Macusani deposits in all occurrences is meta-autunite.

Paragenetic relationships indicate that meta-autunite precipitated directly from a fluid, and is not a product of the in situ alteration of primary U4+ minerals.

. The black phases occurring in close association with meta-autunite, previously described as uraninite and pitchblende, are Fe- and Mn-mineraloids.

. LA-ICP-MS was successfully used to obtain both U-Th and U-Pa apparent ages of the

Macusani meta-autunites. The meta-autunite samples provided averaged U-Th ages at 69 ka, 130 ka, and 314-317 ka, and probably reliable upper discordia-concordia intercepts of ca. 103-113 ka, 210 ka and 400 ka.

. The U-Th-Pa geochronology unambiguosuly indicates that U ore-formation was related to Quaternary, low-temperature, surficial processes. The ages of meta-autunites coincide with both interglacial and glacial periods.

. Stable isotopic techniques for meta-autunite were evaluated and the oxygen isotope fractionation factor for meta-autunite was calculated. The average δ18O values of water calculated to have formed the meta-autunite vary from -21.7‰ to -12.2‰, δ2H values vary from

-181 to -123 ‰ and are consistent with formation of meta-autunite from low-temperature meteoric fluids.

. Based on mineralogical, geochemical and geochronological data and field observations an ore formation model is proposed for the Macusani U deposits. The Macusani U deposits are volcanic-hosted, but the ore-forming process was not of magmatic-hydrothermal nature. The combination of the following critical factors was responsible for the formation of the U deposits in the Macusani area: (1) the large amount of U available from the groundmass of the

134 peraluminous rhyolites of the Macusani Formation, (2) the Tertiary tectonic uplift which caused faulting, significant erosion and canyon incision in the area, (3) the intermittent glacial and interglacial periods which increased meteoric water circulation, (4) mixing of low-temperature fluids and interaction of the fluid with highly absorbing Fe- and Mn-mineraloids caused meta- autunite precipitation.

135

Figure 7.1. Proposed evolution of the Macusani U deposits. (A) 12.3-6.8 Ma: the peraluminous U-enriched rhyolites of the Macusani Formation were erupted. (B) Extensive intermediate-argillic alteration of the rhyolites. Tertiary tectonic uplift caused faulting, significant erosion and canyon incision in the area. (C) Around 3.5 Ma, glaciers formed in the area; alternating glacial and interglacial periods increased erosion and meteoric water circulation, leaching U from the Macusani rhyolites and transporting it along fractures. (D) The main episodes of U ore- formation took place ca. at 69 ka, 130 ka, 314-317 ka, and probably at ca. 103-113 ka, 210 ka and 400 ka.

136

Table 7.1. Main characteristics of volcanic- and granite-hosted U deposits and prospects.

Age of U Name Location Rock types U ore mineralogy Reference mineralization Macusani Peru peraluminous rhyolites >600 ka meta-autunite, weeksite This study , andesite, coffinite-pitchblende-molybdenite, brannerite, trachydacite, rhyolite, Streltsovskoe Russia 134-136 Ma fluorite, pyrite, marcasite, galena, sphalerite, Aleshin et al., 2007 interlayered sedimentary native Cu horizons alkaline and peralkaline Dornot Mongolia rocks: basalt-trachy- 138-135 Ma coffinite, U-titanite, pitchblende is less common Mironov et al. 1993 andesite-rhyolite peralkaline and George-Aniel et al. Sierra Peña Ilmenite-pitchblende-pyrite association, Mexico peraluminous rhyolitic 32-1.6 Ma 1991; Fayek and Ren, Blanca uranophane, weeksite ash-flow sheets 2007 Spor topaz-bearing rhyolites, USA 21-6 Ma weeksite and beta-uranophane Lindsey, 1981 Mountain alkali rhyolites uranophane, Mn- and Pb-oxides, fluorite, pyrite, BaiYangHe China peraluminous rhyolites unknown Shabaga et al., 2013 hematite

Daybreak USA granites, monzanites unknown meta-autunite Dahlkamp, 2010

137 Chapter 8. Cost analysis

The cost of the PhD project is combined from the cost of the laboratory work (Table 8.1), cost of the field-work (Table 8.2), cost of labour (Table 8.3), cost of conference and industry meetings participation (Table 8.4) and student tuitions and fees (Table 8.5). The total cost of the project is $ 308,190 CAN (Table 8.6).

The sources of funding included:

 Cameco Corp. and Vena Resources Inc. bursary to V.Li ($ 48,000 CAN)

 Macusani Yellowcake Inc. bursary to V.Li ($ 48,000 CAN)

 Queen’s University International Graduate Student Award to V.Li ($ 28,900 CAN)

 Society of Economic Geologists travel grant to V.Li ($ 2,000 CAN)

 Society of Economic Geologists student research grant to V.Li ($ 2,500 CAN)

 Queen’s University Dean’s Special Award to V.Li ($ 5,000 CAN)

 Natural Sciences and Engineering Research Council grant to K.Kyser

138 Table 8.1. Cost of the laboratory work

Number of Subtotal, Type of analysis Laboratory Rate, CAD units CAD U-Th-Pa QFIR $1890/day 17 days 32,130 geochronology

U-Pb geochronology QFIR $1890/day 10 days 18,900

Stable Isotopes – δ18O QFIR $70/sample 43 samples 3,010

Stable Isotopes – δ2H QFIR $40/sample 43 samples 1,720

Thin-section Queen's University $40/sample 80 thin sections 3,200 preparation

XRD analysis QFIR $25/sample 50 samples 1,250

SEM QFIR $35/hour 62 hours 2,170

70 hours Microprobe QFIR $35/hour 2,450 (approx.) University of 30 hours Microprobe $80/hour 2,400 Manitoba (approx.) Laboratory $67,230 total

139 Table 8.2. Cost of the field work

Location and Duration Description Subtotal, CAD year Approximately $70 per day of accommodation Macusani, 1 month costs and $2700 of transportation costs 4,800 Peru, 2009 (international and domestic flights) Macusani, Approximately $80 per day of accommodation 3 weeks 4,300 Peru, 2010 costs and $2700 of transportation costs Shipping Based on UPS rate chart, average shipping cost samples from would be around $25/kg; cost calculated for 100 2,500

Peru kg shipment weight

Field total $11,600

Table 8.3. Cost of labour

PhD student's research assistantship Average of $1600/month 72 months 122,400

RA total $122,400

140

Table 8.4. Cost of conference and industry meetings participation

Subtotal, Event Description CAD Cameco, 2010, Approx. $800 for flights and $200 per day of 1,400 Saskatoon, SK accommodation costs (3 days) Cameco, 2012, Approx. $800 for flights and $200 per day of 1,400 Saskatoon, SK accommodation costs (3 days) SEG 2012, Lima, Airfare $1400, $220 for registration and poster printing, 2,320 Peru daily costs of ca. $140/day (5 days) GAC-MAC 2014, $200 of transportation costs, $240 for registration and 1,040 Fredericton, NB poster printing, daily costs of ca. $150/day (4 days) Meetings $61,60 total

Table 8.5. Tuition and student fees

Subtotal, Fees Duration and rate CAD Tuition (for international 21 full-time terms 3 part-time terms 92,400 PhD students) averaging $4100 per term averaging $2100 per term

Other student fees Average of $1200 per academic year (total 7 years) 8,400

Fees total $100,800

141 Table 8.6. Summary of the PhD project costs

Laboratory total $67,230

Field total $11,600

RA total $122,400

Meetings total $6,160

Fees total $100,800

Grand total $308,190

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153 Appendix A. Electron microprobe analyses of rhyolite alteration assemblages

Sample ID 10-IS-30B Illite Location Isivilla ------

SiO2 46.00 45.94 44.16 47.86 44.63 44.67 44.71

Al2O3 23.40 23.29 24.69 27.51 23.92 25.54 24.59

TiO2 0.38 0.19 0.14 0.27 0.30 0.26 0.18

FeO 7.72 8.43 9.43 8.06 9.03 8.59 9.19 MnO 0.63 0.76 0.84 0.81 0.78 0.81 0.81 MgO 0.70 0.16 0.19 0.56 0.19 0.28 0.12 CaO 0.60 0.05 0.07 0.54 0.09 0.22 0.12 BaO 0.03 0.00 0.01 0.02 0.03 0.04 0.03

Na2O 0.31 0.44 0.37 0.28 0.47 0.47 0.42

K2O 7.27 9.52 9.77 7.00 8.85 8.55 9.33

F 7.26 7.82 8.36 8.71 7.39 7.93 7.47 Cl 0.03 0.00 0.00 0.01 0.00 0.01 0.00 Sum 94.32 96.61 98.02 101.63 95.68 97.35 96.97 O = F 3.06 3.29 3.52 3.67 3.11 3.34 3.15 O = Cl 0.006 0.001 0.00 0.002 0.001 0.001 0.001 Total 91.26 93.32 94.50 97.96 92.57 94.01 93.83

154 Sample ID 10-IS-30B Illite

Location Isivilla ------

SiO2 44.55 44.62 44.07 44.83 43.19 43.95

Al2O3 24.45 24.73 24.17 25.87 23.84 23.80

TiO2 0.16 0.13 0.14 0.17 0.10 0.16

FeO 9.74 9.81 9.97 8.80 9.45 9.96

MnO 0.82 0.89 0.90 0.75 0.82 0.88

MgO 0.10 0.09 0.14 0.10 0.18 0.17

CaO 0.11 0.08 0.14 0.10 0.39 0.17

BaO 0.00 0.00 0.00 0.00 0.00 0.02

Na2O 0.33 0.38 0.35 0.37 0.32 0.31

K2O 9.71 9.71 9.31 9.58 8.59 9.17

F 7.93 8.32 7.33 8.45 6.15 7.66 Cl 0.01 0.01 0.00 0.00 0.01 0.01

Sum 97.91 98.76 96.51 99.03 93.04 96.26 O = F 3.34 3.50 3.09 3.56 2.59 3.23

O = Cl 0.002 0.001 0.000 0.001 0.002 0.003

Total 94.57 95.26 93.43 95.47 90.44 93.03

155

Sample ID 10-IS-30B Illite 10 Ta 32 Illite Location Isivilla -- Tantamaco ------

SiO2 44.87 43.22 43.77 44.06 43.28 43.14 42.94

Al2O3 24.96 23.57 22.97 23.20 22.69 22.76 22.63

TiO2 0.15 0.16 0.28 0.38 0.36 0.25 0.28

FeO 9.81 10.13 12.69 12.74 13.18 13.06 12.54 MnO 0.82 0.81 1.02 1.06 1.09 1.11 1.05 MgO 0.16 0.21 0.38 0.41 0.30 0.30 0.47 CaO 0.12 0.29 0.02 0.03 0.02 0.00 0.20 BaO 0.00 0.03 0.00 0.00 0.06 0.00 0.06

Na2O 0.42 0.34 0.35 0.46 0.35 0.36 0.43

K2O 9.56 9.18 9.71 9.60 9.60 9.76 9.49

F 8.17 7.28 8.98 8.07 7.65 8.23 8.08 Cl 0.00 0.01 0.05 0.06 0.06 0.06 0.05 Sum 99.04 95.22 100.23 100.06 98.64 99.03 98.22 O = F 3.44 3.07 0.12 0.16 0.15 0.11 0.12 O = Cl 0.000 0.001 2.03 1.82 1.73 1.86 1.82 Total 95.60 92.15 98.09 98.08 96.76 97.06 96.27

156 Sample ID 10-NC-2 Illite Location Nuevo Corani ------

SiO2 42.89 42.73 45.09 43.70 44.08 43.81 44.58

Al2O3 23.04 22.44 22.15 22.93 21.87 22.20 22.44

TiO2 0.33 0.29 0.25 0.32 0.22 0.18 0.26

FeO 12.97 13.29 12.68 13.25 13.21 12.85 12.99 MnO 0.44 0.46 0.48 0.51 0.45 0.46 0.43 MgO 0.27 0.43 0.41 0.23 0.39 0.24 0.33 CaO 0.28 0.31 0.30 0.53 0.17 0.19 0.34 BaO 0.02 0.00 0.00 0.11 0.07 0.04 0.04

Na2O 0.33 0.31 0.19 0.29 0.22 0.35 0.28

K2O 9.18 9.24 9.07 9.12 9.29 9.25 9.30

F 9.15 8.67 8.45 9.74 8.08 8.92 8.32 Cl 0.04 0.04 0.05 0.03 0.04 0.04 0.04 Sum 98.93 98.20 99.11 100.75 98.10 98.52 99.36 O = F 0.14 0.12 0.10 0.13 0.09 0.07 0.11 O = Cl 2.06 1.96 1.91 2.20 1.82 2.01 1.88 Total 96.73 96.12 97.10 98.42 96.18 96.43 97.37

157 Sample ID 10-NC-2 Illite 10-IS-30B Smectite Location Nuevo Corani -- Isivilla ------

SiO2 49.15 43.87 47.65 46.24 49.53 47.11 45.61

Al2O3 21.42 24.92 24.36 24.85 26.07 25.50 23.49

TiO2 0.15 0.22 0.04 0.00 0.04 0.00 0.06

FeO 11.42 11.45 0.71 0.56 0.74 0.88 0.92 MnO 0.43 0.42 0.05 0.07 0.07 0.06 0.05 MgO 0.26 0.15 0.41 0.48 0.64 0.46 0.47 CaO 0.12 0.04 1.56 1.67 1.68 1.78 1.53 BaO 0.00 0.06 0.00 0.00 0.00 0.00 0.00

Na2O 0.31 0.58 0.52 0.05 0.11 0.07 0.09

K2O 8.72 9.64 0.52 0.10 0.09 0.14 0.14

F 8.57 8.03 0.80 0.96 0.64 0.49 0.72 Cl 0.04 0.05 0.03 0.03 0.04 0.03 0.04 Sum 100.59 99.44 76.65 75.01 79.65 76.53 73.11 O = F 0.06 0.09 0.34 0.40 0.27 0.21 0.30 O = Cl 1.93 1.81 0.01 0.01 0.01 0.01 0.01 Total 98.60 97.53 76.31 74.60 79.37 76.31 72.80

158 Sample ID 10 Ta 32 Smectite Location Tantamaco ------

SiO2 48.59 47.84 47.96 48.59 51.49 49.44 47.23

Al2O3 32.52 31.17 28.56 30.99 23.85 30.09 28.33

TiO2 0.03 0.00 0.06 0.00 0.06 0.06 0.05

FeO 3.01 2.85 2.48 2.62 1.57 2.65 2.59 MnO 0.04 0.03 0.07 0.05 0.08 0.06 0.02 MgO 0.41 0.29 0.39 0.40 0.46 0.41 0.42 CaO 2.14 1.42 1.58 1.36 1.84 1.70 1.29 BaO 0.01 0.07 0.06 0.08 0.00 0.02 0.00

Na2O 0.11 0.10 0.08 0.08 0.06 0.07 0.06

K2O 0.27 0.35 0.13 0.11 0.15 0.13 0.13

F 2.10 1.86 1.57 1.53 2.53 2.08 1.21 Cl 0.03 0.03 0.03 0.06 0.04 0.03 0.04 Sum 89.26 86.01 82.97 85.87 82.12 86.75 81.37 O = F 0.01 0.00 0.02 0.00 0.03 0.03 0.02 O = Cl 0.47 0.42 0.35 0.35 0.57 0.47 0.27 Total 88.77 85.59 82.59 85.53 81.53 86.26 81.08

159 Sample ID 10-NC-2 Smectite Location Nuevo Corani ------

SiO2 44.91 36.25 49.95 47.12 47.68 45.48 47.33

Al2O3 20.78 12.56 19.12 18.07 18.86 10.01 9.87

TiO2 0.01 0.03 0.08 0.01 0.03 0.04 0.01

FeO 7.87 8.28 9.37 11.93 10.84 22.82 23.37 MnO 0.19 0.43 0.18 0.11 0.12 0.02 0.02 MgO 0.67 0.96 0.78 0.91 0.81 0.95 0.90 CaO 1.27 1.70 1.32 1.89 2.21 1.98 1.76 BaO 0.00 0.02 0.03 0.08 0.00 0.04 0.02

Na2O 0.12 0.13 0.10 0.16 0.18 0.02 0.02

K2O 0.87 0.28 0.94 0.69 0.96 0.32 0.33

F 1.13 0.92 1.58 2.09 3.22 1.07 1.02 Cl 0.07 0.08 0.05 0.04 0.06 0.09 0.08 Sum 77.89 61.63 83.50 83.08 84.97 82.83 84.74 O = F 0.01 0.01 0.03 0.00 0.01 0.45 0.43 O = Cl 0.25 0.21 0.36 0.47 0.73 0.02 0.02 Total 77.63 61.41 83.11 82.61 84.23 82.36 84.29

160 Sample ID 10-NC-2 Smectite Location Nuevo Corani -- --

SiO2 45.57 45.84 46.43

Al2O3 9.24 9.36 8.99

TiO2 0.05 0.02 0.03

FeO 23.34 22.91 23.44 MnO 0.00 0.01 0.03 MgO 0.99 1.11 0.95 CaO 2.00 1.93 1.80 BaO 0.04 0.05 0.00

Na2O 0.08 0.09 0.07

K2O 0.32 0.29 0.30

F 0.89 1.75 1.22 Cl 0.07 0.06 0.08 Sum 82.61 83.41 83.34 O = F 0.38 0.74 0.51 O = Cl 0.02 0.01 0.02 Total 82.21 82.66 82.81

161 Appendix B. Electron microprobe analyses of Mn- and Fe- mineraloids

Mn-mineraloids Location Colibri II, sample Clb-2-1- Point 1 /1 2 /1 3 /1 4 /1 5 /1 6 /1 7 /1 8 /1 9 /1

Na2O 0.22 0.21 0.27 0.34 0.25 0.32 0.25 0.29 0.33

SiO2 0.63 0.69 0.57 0.63 0.61 0.63 0.67 0.61 0.53 MgO 0.76 0.76 0.84 0.83 0.85 0.92 0.83 0.86 0.81

Al2O3 3.38 3.68 3.55 3.52 3.34 3.26 3.77 3.36 3.00

K2O 2.05 2.06 2.13 2.18 2.26 2.25 2.27 2.20 2.31

P2O5 0.32 0.33 0.30 0.33 0.29 0.30 0.33 0.30 0.30 CaO 2.01 1.86 1.86 1.70 1.62 1.62 1.65 1.74 1.71 MnO 58.89 60.33 59.75 59.96 60.92 61.07 60.40 59.90 60.42 FeO 0.99 0.83 0.70 0.41 0.34 0.21 0.45 0.59 0.57

TiO2 0.00 - - 0.02 0.02 0.05 - - - SrO 0.36 0.46 0.26 0.35 0.26 0.16 0.36 0.36 0.34 Total 69.61 71.21 70.24 70.27 70.77 70.79 70.97 70.22 70.32

Mn-mineraloids Location Nuevo Corani, sample Mac 202 Point 10 /1 11 /1 12 /1 13 /1 14 /1 15 /1 16 /1 17 /1 18 /1

Na2O 0.26 0.26 0.14 0.23 0.21 0.19 0.29 0.24 0.09

SiO2 18.72 17.98 10.60 16.49 17.78 14.62 12.86 11.82 0.54 MgO 0.39 0.31 0.33 0.36 0.34 0.32 0.32 0.34 0.43

Al2O3 12.56 12.02 7.92 10.91 11.91 10.21 8.31 8.32 1.84

K2O 2.08 1.92 1.61 1.92 1.88 1.79 1.81 1.83 1.82

P2O5 0.29 0.38 0.33 0.30 0.35 0.31 0.33 0.33 0.41 CaO 1.99 2.12 2.26 1.97 1.95 2.27 2.29 2.40 2.29 MnO 40.53 41.23 51.52 44.29 42.06 45.33 47.99 48.38 64.69 FeO 1.42 1.08 0.75 1.14 1.15 0.98 0.99 0.89 0.36

TiO2 0.11 0.02 0.03 0.07 0.11 0.04 - 0.08 0.02 SrO 0.26 0.16 0.13 0.18 0.11 0.20 0.17 0.21 0.37 Total 78.59 77.48 75.61 77.87 77.84 76.26 75.37 74.85 72.86

162 Mn-mineraloids Location Nuevo Corani, sample Mac 202 Point 19 /1 20 /1 21 /1 22 /1 23 /1 24 /1 25 /1 26 /1 27 /1

Na2O 0.13 0.11 0.13 0.12 0.25 0.17 0.50 0.75 0.48

SiO2 0.54 0.49 20.83 19.64 21.63 21.21 26.30 28.68 22.95 MgO 0.30 0.42 0.36 0.34 0.35 0.38 0.62 0.43 0.39

Al2O3 1.80 2.10 13.13 13.18 12.86 13.60 13.48 13.68 10.90

K2O 1.97 2.16 1.46 1.19 1.72 1.51 3.28 4.45 3.25

P2O5 0.47 0.48 0.22 0.20 0.25 0.21 0.43 0.42 1.37 CaO 1.93 1.90 2.30 2.39 2.24 2.53 1.59 1.56 1.64 MnO 62.60 66.06 38.18 37.86 37.73 38.46 32.46 31.33 34.40 FeO 0.25 0.28 1.34 1.34 1.48 1.55 2.57 1.51 1.84

TiO2 0.04 - 0.10 0.18 0.13 0.10 0.26 0.05 0.10 SrO 0.38 0.42 0.09 0.08 0.12 0.10 0.18 0.15 0.18 Total 70.40 74.41 78.14 76.50 78.75 79.80 81.66 83.00 77.50

Mn-mineraloids Location Nuevo Corani, sample Mac 202 Point 28 /1 29 /1 30 /1 31 /1 32 /1 33 /1 34 /1 35 /1 36 /1 37 /1

Na2O 0.27 0.13 0.19 0.17 0.17 0.15 0.38 0.77 1.09 0.49

SiO2 19.93 0.57 2.72 1.36 0.56 0.74 25.81 50.45 39.32 33.47 MgO 0.36 0.64 0.63 0.68 0.58 0.67 0.75 0.18 0.21 1.35

Al2O3 12.60 3.11 2.57 4.62 2.55 3.22 15.53 9.89 12.35 11.75

K2O 2.13 1.97 2.38 1.81 2.08 1.84 4.24 2.85 5.23 2.84

P2O5 0.47 0.28 1.02 0.20 0.26 0.18 0.43 1.02 0.60 0.55 CaO 1.92 1.93 2.06 1.91 1.79 1.93 1.39 1.01 1.06 1.25 MnO 40.49 63.55 60.53 59.94 63.17 62.14 29.86 20.30 26.53 29.01 FeO 1.11 0.22 0.13 0.22 0.28 0.21 2.65 0.61 0.70 3.85

TiO2 0.08 0.03 0.01 0.02 - - 0.25 0.05 0.06 0.11 SrO 0.23 0.27 0.36 0.30 0.35 0.30 0.23 0.21 0.13 0.17 Total 79.57 72.69 72.60 71.21 71.79 71.38 81.50 87.35 87.28 84.82

163

Fe-Si phase Location Pinocho, sample Pi-1 Sample ID Pi-1-16 Pi-1-17 Pi-1-18 Pi-1-24 Pi-1-25 Pi-1-26

Na2O 0.16 0.02 0.03 0.03 0.03

SiO2 19.15 15.20 16.21 14.74 17.27 19.14 MgO 0.23 0.11 0.22 0.18 0.14 0.10

Al2O3 1.17 1.16 2.50 1.54 1.42 1.31

P2O5 1.69 1.63 1.00 1.26 2.11 1.68 CaO 1.23 1.25 0.91 0.98 1.15 0.92 MnO 0.10 0.15 0.03 0.03 0.20 0.08

Fe2O3 64.17 62.60 42.87 49.11 65.31 64.44

TiO2 0.06 0.08 0.03 0.01 0.02 0.00 SrO 0.03 0.11 0.02 0.00 0.04 0.00 BaO 0.06 0.09 0.05 0.12 0.00 0.08

UO3 0.45 0.47 0.49 0.32 0.48 0.39 Total 88.33 83.02 64.33 68.31 88.16 88.16

Fe-Si phase Location Pinocho, sample Pi-1 Sample ID Pi-1-27 Pi-1-28 Pi-1-40 Pi-1-41 Pi-1-42

Na2O 0.03 0.04 0.07 0.05 0.00

SiO2 22.83 24.07 22.24 33.88 21.62 MgO 0.17 0.26 0.19 0.48 0.37

Al2O3 1.52 1.52 1.83 3.43 2.87

P2O5 1.50 1.66 1.47 1.06 1.54 CaO 1.05 1.31 1.14 1.37 0.96 MnO 0.03 0.06 0.03 0.05 0.05

Fe2O3 61.33 61.98 63.61 53.94 52.44

TiO2 0.04 0.00 0.04 0.11 0.05 SrO 0.04 0.01 0.00 0.04 0.00 BaO 0.09 0.04 0.12 0.08 0.02

UO3 0.31 0.45 0.27 0.14 0.61 Total 88.93 91.38 91.00 94.62 80.53

164 Appendix C. Electron microprobe data for meta-autunites

Sample ID 10-CR-9 10-CR-10 10-CR-11 10-CR-12 10-CR-13 Location Calvario Real, sample 10-CR-9 Average Minimum Maximum Standard Deviation

SiO2 0.027 0.164 0.188 1.431 0.606 0.483 0.027 1.431 0.572

Al2O3 0.006 0.030 0.094 0.802 0.512 0.289 0.006 0.802 0.353

K2O 0.896 1.177 3.140 0.610 0.421 1.249 0.421 3.140 1.095 BaO 0.000 0.000 0.075 0.101 0.000 0.035 0.000 0.101 0.049

ThO2 0.000 0.000 0.000 0.000 0.061 0.012 0.000 0.061 0.027

UO3 63.040 65.190 65.800 64.790 66.980 65.160 63.040 66.980 1.445 CaO 5.060 5.430 4.080 5.820 6.040 5.286 4.080 6.040 0.771

Na2O 0.131 0.126 0.000 0.087 0.035 0.076 0.000 0.131 0.057 MgO 0.098 0.201 0.054 0.039 0.118 0.102 0.039 0.201 0.064

P2O5 16.700 16.990 18.320 16.430 16.450 16.978 16.430 18.320 0.784 MnO 0.178 0.161 0.000 0.000 0.000 0.068 0.000 0.178 0.093

Fe2O3 0.020 0.025 0.047 0.233 0.024 0.070 0.020 0.233 0.092 Total 86.156 89.494 91.797 90.343 91.247 89.807 86.156 91.797 2.222

165 Sample ID Clb-2-1 Clb-2-1 Clb-2-1 Clb-2-1 Clb-2-1 Clb-2-1 Clb-2-1 Clb-2-1 Clb-2-1 Clb-2-1 Clb-2-1 Clb-2-1 Location Colibri II, sample Clb-2-1

SiO2 0.151 0.018 - 0.114 0.076 3.270 3.555 3.597 2.564 4.168 2.939 0.940

Al2O3 - - - - 0.028 0.707 1.901 1.834 1.262 2.141 1.637 0.381

K2O 0.007 0.011 0.001 0.156 0.106 0.569 0.145 0.213 0.098 0.194 0.188 0.119 BaO na na na na na na na na na na na na

ThO2 - - 0.024 0.008 - - - - 0.016 0.032 - 0.073

UO3 65.846 57.172 67.415 68.134 63.906 61.364 59.535 61.966 58.619 59.841 60.327 64.318 CaO 5.844 5.301 6.171 5.687 5.840 5.290 5.438 5.780 5.220 5.742 5.387 5.439 NaO ------0.050 - 0.015 - 0.026 0.006 MgO - 0.001 0.016 0.000 - 0.021 0.091 0.078 0.059 0.097 0.040 0.030

P2O5 16.891 14.771 16.612 16.492 16.356 15.578 15.055 15.801 12.719 15.317 15.053 16.569 MnO 0.046 - - 0.022 - - 0.045 0.024 0.005 0.013 0.048 0.041

Fe2O3 0.000 0.000 0.000 0.095 0.000 0.000 0.154 0.164 0.181 0.300 0.165 0.014

TiO2 0.051 - 0.000 0.040 0.064 0.000 0.000 0.000 0.013 0.056 0.095 0.029

Cr2O3 0.024 0.000 0.000 0.028 0.000 0.036 0.000 0.000 0.030 0.000 0.000 0.000

V2O5 0.000 0.166 0.005 0.000 0.036 0.000 0.031 0.025 0.000 - 0.000 0.000 PbO 0.000 0.014 0.205 0.000 0.168 0.000 0.000 0.000 0.010 0.000 0.000 0.000

SO2 0.028 0.009 0.000 0.000 0.000 - 0.000 0.014 0.002 0.014 0.000 0.014

Y2O3 0.057 0.012 - 0.021 0.011 0.133 0.014 0.160 0.000 0.093 0.051 0.024

Tb2O3 0.000 0.011 0.041 0.013 0.000 0.082 0.000 0.000 0.014 0.000 0.012 0.041 Total 88.930 77.465 90.476 90.804 86.573 87.035 86.007 89.647 80.825 88.000 85.964 88.038

166 Sample ID Clb-2-1 Clb-2-1 Clb-2-1 Clb-2-1 Clb-2-1 Clb-2-1 Standard Location Colibri II, Clb-2-1 Average Minimum Maximum Deviation

SiO2 3.340 3.584 2.010 1.716 2.632 1.531 2.011 0.000 4.168 1.480

Al2O3 1.612 1.630 0.864 0.686 1.132 0.717 0.918 0.000 2.141 0.750

K2O 0.298 0.315 0.244 0.278 0.233 0.243 0.190 0.001 0.569 0.135 BaO na na na na na na - 0.000 0.000 na

ThO2 0.004 - - - - 0.002 0.006 0.000 0.073 0.020

UO3 62.010 62.046 65.004 64.588 62.788 64.193 62.726 57.172 68.134 2.981 CaO 5.403 5.456 5.811 5.456 5.366 5.548 5.565 5.220 6.171 0.253 NaO 0.023 0.033 0.014 0.032 - 0.018 0.010 0.000 0.050 0.017 MgO - 0.021 0.007 - - - 0.025 0.000 0.097 0.034

P2O5 15.401 15.928 16.401 17.062 16.238 16.888 15.840 12.719 17.062 1.047 MnO 0.052 0.051 0.022 0.047 0.000 0.039 0.024 0.000 0.052 0.022

Fe2O3 0.247 0.242 0.071 0.077 0.165 0.060 0.107 0.000 0.300 0.098

TiO2 0.032 0.070 0.017 0.017 0.000 0.000 0.027 0.000 0.095 0.030

Cr2O3 0.000 0.000 0.000 0.023 - - 0.008 0.000 0.036 0.013

V2O5 0.015 0.000 0.037 0.000 0.094 0.000 0.022 0.000 0.166 0.043 PbO 0.000 0.000 0.002 0.012 0.025 0.000 0.024 0.000 0.205 0.060

SO2 0.024 0.000 0.000 0.000 -0.003 0.000 0.005 0.000 0.028 0.009

Y2O3 0.121 0.070 0.112 0.066 0.137 0.099 0.065 0.000 0.160 0.053

Tb2O3 0.079 0.000 0.161 0.121 0.000 0.023 0.033 0.000 0.161 0.047 Total 88.656 89.439 90.772 90.171 88.795 89.358 87.609 77.465 90.804 3.479

167 Sample ID 206-1 206-2 206-3 206-4 206-5 206-6 206-7 206-8 206-9 206-10 206-11 206-12 Location Tantamaco, sample Mac-206

SiO2 0.806 0.652 0.624 0.748 0.638 0.638 0.706 0.650 0.543 0.723 0.363 0.124

Al2O3 0.584 0.206 0.114 0.099 0.198 0.715 0.742 2.760 0.121 0.284 1.654 0.069

K2O 0.054 0.015 0.130 0.043 0.009 0.000 0.057 0.215 0.051 0.073 0.058 0.007 BaO na na na na na na na na na na na na

ThO2 0.013 0.000 0.000 0.007 0.000 0.006 0.000 0.000 0.006 0.005 0.000 0.004

UO3 68.794 66.860 65.802 66.705 67.226 65.793 61.502 64.956 62.086 63.183 61.786 63.378 CaO 4.655 4.901 4.788 5.005 5.067 4.264 3.695 1.837 4.322 4.214 3.010 4.018

Na2O 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 MgO 0.000 0.000 0.000 0.000 0.000 0.000 0.003 0.000 0.000 0.000 0.074 0.013

P2O5 14.626 14.417 15.148 14.013 13.606 13.763 16.715 15.453 14.071 15.089 15.738 15.652 MnO 0.045 0.000 0.042 0.039 0.055 0.011 -0.002 0.000 0.000 0.023 0.000 0.000

Fe2O3 - 0.000 - 0.062 0.015 0.071 3.013 0.142 0.796 0.849 0.893 0.168

TiO2 0.039 0.000 0.000 0.038 0.034 0.045 0.000 0.036 0.043 0.025 0.072 0.050

Cr2O3 0.000 0.000 0.000 0.002 0.000 0.030 0.000 0.027 0.007 0.000 0.026 0.026

V2O5 0.047 0.041 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.018 PbO 0.012 0.000 0.031 0.028 0.101 0.000 0.003 0.000 0.020 0.001 0.000 0.088

SO2 0.016 0.008 0.027 - 0.010 0.006 0.024 - 0.013 0.000 0.002 0.000

Y2O3 0.504 0.439 0.245 0.121 0.360 0.568 0.370 0.246 0.233 0.595 0.013 0.006

Tb2O3 0.000 0.000 0.060 0.000 0.000 0.033 0.000 0.028 0.000 0.008 0.000 0.071 CuO 0.005 0.000 0.007 0.031 0.048 0.045 0.045 0.000 0.000 0.000 0.000 0.038 Total 90.197 87.538 87.015 86.938 87.365 85.987 86.873 86.346 82.310 85.072 83.689 83.730

168 Sample ID 206-13 206-14 206-15 206-16 206-17 206-18 Standard Location Tantamaco, sample Mac-206 Average Minimum Maximum Deviation

SiO2 0.167 0.230 0.364 0.295 0.764 0.299 0.518 0.124 0.806 0.224

Al2O3 0.098 0.085 0.452 0.037 0.322 0.356 0.494 0.037 2.760 0.687

K2O 0.028 0.000 0.050 0.007 0.051 0.036 0.049 0.000 0.215 0.052 BaO na na na na na na na na na na

ThO2 0.043 -0.003 0.000 -0.003 0.000 0.000 0.004 -0.003 0.043 0.011

UO3 64.475 63.043 63.945 64.753 65.330 61.832 64.525 61.502 68.794 2.105 CaO 4.304 4.211 3.959 4.438 4.528 3.909 4.174 1.837 5.067 0.769 NaO 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 MgO 0.001 0.000 0.000 0.000 0.000 0.013 0.006 0.000 0.074 0.017

P2O5 15.225 15.823 15.206 15.604 14.885 15.104 15.008 13.606 16.715 0.808 MnO 0.000 0.016 0.000 0.000 0.012 0.000 0.013 -0.002 0.055 0.019

Fe2O3 0.459 0.486 0.647 0.339 0.410 0.252 0.478 0.000 3.013 0.703

TiO2 0.019 0.010 0.000 0.000 0.067 0.000 0.027 0.000 0.072 0.024

Cr2O3 0.000 0.000 0.000 0.024 - 0.000 0.008 0.000 0.030 0.012

V2O5 0.000 0.000 0.029 0.000 0.000 0.118 0.014 0.000 0.118 0.030 PbO 0.065 0.045 0.000 0.027 0.000 0.000 0.023 0.000 0.101 0.032

SO2 0.027 0.014 0.007 0.000 0.014 0.015 0.010 0.000 0.027 0.010

Y2O3 0.000 0.000 0.043 0.000 0.345 0.000 0.227 0.000 0.595 0.213

Tb2O3 0.000 0.000 0.004 0.000 0.143 0.104 0.025 0.000 0.143 0.042 Total 0.091 0.004 0.058 0.000 0.009 0.020 0.022 0.000 0.091 0.027 85.003 83.964 84.762 85.522 86.874 82.057 85.625 82.057 90.197 2.033

169 Sample ID 202-1 202-2 202-3 202-4 202-5 202-6 202-7 202-8 Location Nuevo Corani, sample Mac-202

SiO2 3.444 0.429 0.751 0.670 4.225 0.459 0.766 0.257

Al2O3 2.144 0.151 0.119 0.116 1.160 0.054 0.221 0.004

K2O 0.351 0.175 0.306 0.164 0.595 0.222 0.182 0.139 BaO na na na na na na na na

ThO2 0.008 0.026 0.000 0.037 0.000 0.000 0.000 0.032

UO3 63.057 69.030 65.639 65.924 59.307 57.193 60.304 65.307 CaO 4.911 5.734 5.323 5.876 4.195 3.790 4.280 4.756

Na2O 0.000 0.000 0.000 0.000 0.015 0.000 0.000 0.000 MgO 0.028 - 0.000 0.022 0.016 0.000 0.000 0.000

P2O5 15.198 17.874 15.091 14.857 12.984 17.151 11.551 12.585 MnO 0.069 0.112 0.607 0.038 0.082 0.314 0.400 0.252

Fe2O3 0.066 0.000 0.000 0.091 0.007 0.002 0.021 0.000

TiO2 0.088 0.014 0.041 0.013 0.000 0.025 0.042 0.000

Cr2O3 0.000 0.012 0.012 0.012 0.002 0.031 0.020 0.000

V2O5 0.000 0.046 0.000 0.095 0.035 0.000 0.084 0.003 PbO 0.000 0.000 0.098 0.000 0.017 0.000 0.069 0.000

SO2 0.000 0.000 0.007 - 0.000 0.027 - 0.000

Y2O3 0.009 0.009 0.011 0.100 0.041 0.031 0.092 0.037

Tb2O3 0.034 0.214 0.050 0.000 0.000 0.045 0.083 0.004 Total 89.406 93.821 88.055 88.000 82.681 79.342 78.114 83.374

170 Sample ID 202-9 202-10 202-11 202-12 Standard Location Nuevo Corani, sample Mac-202 Average Minimum Maximum Deviation

SiO2 0.530 0.882 0.564 0.740 1.143 0.257 4.225 1.280

Al2O3 0.038 0.415 0.037 0.064 0.377 0.004 2.144 0.641

K2O 0.296 0.357 0.225 0.135 0.262 0.135 0.595 0.131 BaO na na na na 0.000 0.000 na

ThO2 0.015 0.011 0.000 0.000 0.011 0.000 0.037 0.014

UO3 64.942 64.676 68.716 64.436 64.044 57.193 69.030 3.568 CaO 5.121 5.580 5.104 4.822 4.958 3.790 5.876 0.638

Na2O 0.047 - 0.000 0.000 0.005 0.000 0.047 0.014 MgO 0.000 0.000 0.000 0.000 0.000 0.000 0.028 0.011

P2O5 15.944 16.339 16.996 11.383 14.829 11.383 17.874 2.219 MnO 0.429 0.304 0.802 0.118 0.294 0.038 0.802 0.236

Fe2O3 0.000 0.387 0.000 0.000 0.048 0.000 0.387 0.111

TiO2 0.029 0.036 0.107 0.030 0.035 0.000 0.107 0.032

Cr2O3 0.000 0.048 0.000 - 0.011 0.000 0.048 0.015

V2O5 0.000 0.067 0.111 0.000 0.000 0.000 0.111 0.043 PbO 0.000 0.000 0.000 0.003 0.016 0.000 0.098 0.033

SO2 0.000 0.012 0.000 0.000 0.002 0.000 0.027 0.010

Y2O3 0.100 0.026 0.096 - 0.045 0.000 0.100 0.040

Tb2O3 0.000 0.000 0.000 0.068 0.041 0.000 0.214 0.062 Total 87.490 89.137 92.757 81.791 86.122 78.114 93.821 5.050

171 Sample ID Tut-1-1 Tut-1-2 Tut-1-3 Tut-1-4 Tut-1-5 Tut-1-6 Tut-1-7 Tut-1-8 Location Tuturumani, sample Tut-1 SiO2 0.451 0.382 0.309 0.507 1.532 1.041 0.567 0.254 Al2O3 0.125 0.035 0.068 0.014 0.579 0.346 0.027 0.026 K2O 0.031 0.092 0.052 0.031 0.046 0.052 0.032 0.017 BaO na na na na na na na na ThO2 0.000 0.000 0.038 0.017 0.002 0.000 0.099 - UO3 64.328 61.333 64.677 66.736 63.533 60.947 63.858 63.700 CaO 4.776 4.740 4.558 5.053 4.385 4.461 4.630 4.630 Na2O 0.000 - 0.000 0.000 0.216 0.037 0.000 0.000 MgO 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 P2O5 16.317 15.576 16.425 16.124 15.986 15.772 16.091 16.406 MnO 0.000 0.000 0.032 0.073 0.022 0.000 0.000 0.006 Fe2O3 0.123 0.000 0.043 0.139 0.008 0.200 0.421 0.537 TiO2 0.000 0.002 0.000 0.067 0.018 0.012 0.011 0.053 Cr2O3 0.000 0.033 0.000 0.051 0.000 0.018 0.001 0.009 V2O5 0.087 0.000 0.000 0.000 0.126 0.000 0.000 0.000 PbO 0.000 0.123 0.000 0.000 0.000 0.083 0.124 0.076 SO2 0.000 0.020 0.000 0.030 0.001 0.011 0.000 0.017 Y2O3 - 0.000 0.081 0.000 0.003 0.135 - 0.050 Tb2O3 0.000 0.000 0.120 0.000 0.000 0.000 0.000 0.000 Total 86.235 82.335 86.402 88.842 86.456 83.113 85.859 85.776

172 Sample ID Tut-1-9 Tut-1-10 Tut-1-11 Tut-1-12 Tut-1-13 Location Tuturumani, sample Tut-1 Average Minimum Maximum Standard Deviation SiO2 0.157 0.668 0.198 0.160 0.270 0.500 0.157 1.532 0.396 Al2O3 0.035 0.022 0.022 0.018 0.047 0.105 0.014 0.579 0.168 K2O 0.053 0.033 0.029 0.036 0.047 0.042 0.017 0.092 0.019 BaO na na na na na 0.000 0.000 na ThO2 0.000 0.000 0.000 0.000 0.054 0.016 0.000 0.099 0.031 UO3 65.632 63.057 67.072 64.981 65.308 64.243 60.947 67.072 1.819 CaO 4.680 4.345 4.646 4.691 4.616 4.632 4.345 5.053 0.181 Na2O - 0.000 0.021 0.022 0.000 0.022 0.000 0.216 0.060 MgO 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 P2O5 15.561 15.528 16.831 16.199 16.422 16.095 15.528 16.831 0.399 MnO 0.060 0.034 0.000 0.000 0.009 0.018 0.000 0.073 0.025 Fe2O3 0.000 0.061 0.033 0.134 0.015 0.132 0.000 0.537 0.168 TiO2 0.000 0.025 0.052 0.025 0.000 0.020 0.000 0.067 0.023 Cr2O3 0.028 0.000 0.037 0.031 0.000 0.016 0.000 0.051 0.018 V2O5 0.000 0.000 0.041 0.000 0.111 0.028 0.000 0.126 0.048 PbO 0.000 0.154 0.000 0.011 0.022 0.045 0.000 0.154 0.058 SO2 0.013 0.001 0.003 0.000 0.000 0.007 0.000 0.030 0.010 Y2O3 0.005 0.160 0.050 0.000 0.036 0.040 0.000 0.160 0.055 Tb2O3 0.000 0.065 0.152 0.164 0.000 0.039 0.000 0.164 0.064 Total 86.219 84.153 89.185 86.470 86.957 86.000 82.335 89.185 1.938

173 Appendix D. Composition of meta-autunite (ICP-MS)

Sample ID M206-1 M206-2 M207 NC-1 Chi-5 Chi-6-1 Tut-1 Is-2 Pi-1 Pi-2 Clb-2

Location Tantamaco Nuevo Corani Chilcuno Tuturumani Isivilla Pinocho Colibri

Major elements (wt. %)

Ca 1.94 1.85 3.83 2.73 3.04 1.34 3.14 2.4 2.58 4.93 2.61

Fe 0.5 2.16 0.53 0.32 11.88 0.06 1.18 0.15 33.53 5.02 0.06

Pb 0.04 0.05 0.03 0.03 0.06 0.06 0.03 0.03 0.02 0.04 0.05

Th 0.37 0.37 0.35 0.29 0.31 0.43 0.32 0.32 0.26 0.34 0.4

U 53.46 51.63 52.59 44.2 37.06 63.31 47.36 47.52 11.39 46.5 59.33

V ------

P 6.34 6.29 6.83 5.64 5.4 1.49 5.83 6.21 1.81 7.16 3.77

Trace elements (ppm)

Total 62.66 62.35 64.16 53.21 57.76 66.69 57.86 56.64 49.59 63.99 66.21

Al 11178.5 11175.2 12747.1 8860.8 6525.9 13954.4 12755.6 5915.4 28057 18287.1 8695.6

As 3581.3 3962.9 1387.8 1717.9 1562.4 194 4184 1116.8 2267.5 1495.8 743.5

Au ------

B ------

Ba 1721.7 3229.7 2571.1 2906.9 284.4 911.7 4263.3 7406 1218.8 2035.4 64.4

Be 210 195.2 122.8 235.4 1629.3 3137.4 249.1 140.5 1111.2 3785.2 1977.1

Bi 24.32 25.56 6.71 51.37 - 12.23 36.24 11.29 2.57 3.68 9.26

Cd - - - - 107 - - - 5.25 - -

Co - - - - 10.09 - - - 34.51 28.98 -

Cr - - 4.48 - - - 1.83 - 12.73 23 -

Cs 12.34 4.45 13.77 27.75 25.92 352.46 23.77 9.78 116.44 74.56 317.68

Cu 21.61 43.33 40.08 11.76 12.44 17.06 93.91 16.35 47.29 20.42 10.29

Dy - 201.05 17.82 53.42 28.08 47.69 64.07 19.92 7.47 9.68 58.77

Er 82.04 180.63 19.22 91.93 17.66 14.54 43.35 13.72 5.39 8.55 37.74

Eu 1.44 2.95 3.85 0.58 1.95 5.97 5.01 0.22 0.82 0.27 5.01

Gd 24.77 44.69 2.96 6.77 26.6 58.23 46.1 5.91 6.24 4.57 41.58

Hg ------

Ho 28.57 49.04 4.23 16.91 5.34 6.4 12.38 4.07 1.59 2.46 12.1

K 1472.3 2674.1 1571.4 5062.2 1325 41336.5 1151.6 960.6 1820.1 1714.4 29817.8

La 53.83 110.62 5.08 13.97 4.88 252.06 106.32 4.36 11.16 6.23 189.05

Li 10.14 7.25 97 120.56 72.59 7.32 134.76 52.59 98.09 176.58 5.66

Lu 3.98 8.86 5.96 38.66 5.78 14.52 9.56 2.93 1.18 1.6 3.86

174 Mg 301.2 319.9 499.4 432.1 762.5 366.7 866 281.6 5031.4 3428 314

Mn 20.5 51.01 85.74 160.7 92.51 170.03 131.3 36.08 307.23 67.55 28.64

Na 587.9 679.7 102.9 1086.7 1314 262.6 830.3 448 922.7 569.2 833.2

Nb 6.73 8.4 1.63 0.65 - 4.88 2.96 0.66 26.12 3.07 0.48

Nd 39.94 86.58 4.91 22.11 236.92 175.78 6.3 17.17 8.27 15.99 191.12

Ni 0.43 - 17.13 11.08 - 29.19 - 11.13 7.61 9.9 -

P ------

Pb 8.66 12.32 16.6 26.66 15.37 32.22 20.34 14.9 6.03 35.01 5.88

Pd 64.53 88.66 20.42 11.72 19.63 14.1 1.43 6.81 55.26 35.17

Pr 11.47 24.36 1.4 3.91 60.82 40.91 1.35 3.91 1.93 3.97 50.58

Rb 132.1 183.5 49 48.2 4095.3 107 50.5 60.7 68.5 138.7 2331.8

Re ------

S ------

Sb 0.67 2.11 - 0.15 - - - 0.69 0.82 - -

Sc - - - - - 2.11 - 4.57 - - -

Se ------

Si 84.3 105.5 272.6 0 820.6 438.1 342 368.3 321.9 385.4 771.5

Sm 15.65 31.61 39.71 14.24 61.44 53.34 3.25 5.86 2.79 5.45 49.82

Sr 11045.3 9105.3 12066.8 7171.9 1342.6 14303 11853.7 2484.2 8079.9 11532 4476.8

Tb 12.82 17.81 1.44 4.68 9.5 9.37 2.47 18.89 3.53 8.21

Te ------

Th 2.2 2.92 15.07 10.2 9.04 2.17 2.42 2.27 20.64 10.76

Ti 20.23 13.69 99.14 2.23 4.4 185.19 54.7 11.68 119.07 63.39 18.62

Tl 6.35 12.07 1.57 49.76 18.63 4.92 6.11 13.27 1.56 3.49

Tm 7.86 18.97 4.62 2.37 1.77 7.87 2.57 0.86 1.46 25.83 5.38

V 6.42 3.82 57.13 2.89 5.02 96.43 20.46 3.57 2.49

Y 1383.7 2729.9 283.8 225.9 177.5 615.3 196.6 66.2 170.2 1219.8 539.7

Yb 32.12 73.11 44.15 12.42 10.66 71.21 21.39 5.98 9.87 266.9 31.52

Zn 87.1 183.5 188.5 261.6 119.3 257.3 29.3 895.5 469.2 107.9 131.2

Zr 1.83 1.12 - - - - 0.53 0.41 2.25 1.18 -

Total trace (wt.%) 0.227 0.446 0.055 0.050 0.031 0.095 0.026 0.101 0.066 0.160 0.070

Total all 62.88 62.80 64.22 57.81 66.72 57.95 56.66 49.69 64.06 53.37 66.28

175 Appendix E. U-Pb isotope ratios

The U-Pb method was conducted on the Macusani samples for preliminary age determination. LA-ICP-MS was used to obtain Pb/Pb and U/Pb isotope ratios of the mineralization and therefore to determine the age of the U mineralization. Meta-autunite sample were ablated by a frequency-quintupled (213 nm) Nd-YAG laser (LUV213, New Wave-

Merchantek, Fremont, California) and then brought in to a Finnigan Mat Element HR-ISP-MS

(Finnigan MAT, Bremen, Germany). The operating parameters used for ablation were 50 μm spot size, laser power 45%, fire rate 2 Hz, fluency 0.033mJ.

Before taking measurements of U and Pb isotope ratios, the instrument was calibrated and check carried out using in-house davidite standard which has been well characterized. Every second measurement was a gas blank flowing through the laser sample chamber. Correction for

Hg was made.

U-Pb isotopic ratios for meta- autunite from Pinocho prospect

Pb comm, % 207Pb/206Pb ±er 206Pb/238U ±er 207Pb/235U ±er

Pl_1h 52.45 0.762 0.044 0.00016 0.00003 0.00683 0.00135 Pl_1f 48.56 0.644 0.036 0.00008 0.00001 0.00170 0.00016 Pl_1g 56.34 0.705 0.039 0.00016 0.00002 0.00244 0.00023 Pl_1e 0.00 0.117 0.050 0.00005 0.00002 0.00084 0.00027 Pl_1d 0.00 0.354 0.272 0.00006 0.00020 0.00295 0.00191

176

Ages derived from ratios for meta-autunite from Pinocho prospect

Age 207Pb/206Pb, Ma Age 206Pb/238U, Ma Age 207Pb/235U, Ma discordance

Pl_1h 4852.58 1.01 6.92 99.98 Pl_1f 4611.34 0.51 1.72 99.99 Pl_1g 4740.64 1.06 2.48 99.98 Pl_1e 1909.06 0.35 0.86 99.98 Pl_1d 3724.61 0.41 2.99 99.99

177 Appendix F. U-Th-Pa isotope ratios

Ratio Sample ID Mineral Location 234U/238U 232Th/238U 230Th/232Th 231Pa/235U 230Th/238U 230Th/234U Clb21-1 Autunite Colibri 5.319E-05 2.490E-06 4.818E+00 2.213E-05 6.282E-06 1.185E-01 Clb21-2 -- 5.604E-05 3.371E-06 3.530E+00 3.225E-05 7.871E-06 1.400E-01 Clb21-3 -- Clb21-4 -- 5.517E-05 3.029E-06 2.883E+00 2.660E-05 7.105E-06 1.286E-01 Clb21-5 -- 5.712E-05 4.205E-06 2.203E+00 3.122E-05 7.890E-06 1.380E-01 Clb21-6 -- 5.420E-05 1.283E-05 6.598E-01 3.182E-05 7.274E-06 1.332E-01 Clb21-7 -- 5.410E-05 1.206E-05 8.367E-01 3.398E-05 7.585E-06 1.401E-01 Clb21-8 -- 5.340E-05 9.190E-06 8.959E-01 3.461E-05 7.024E-06 1.313E-01 Clb21-9 -- 5.093E-05 2.718E-05 4.791E-01 6.592E-05 6.107E-06 1.196E-01 Clb21-10 -- 5.400E-05 3.381E-06 2.905E+00 4.108E-05 7.355E-06 1.363E-01

Clb_2_1 Autunite Colibri 6.224E-05 1.322E-05 5.663E-01 4.875E-05 6.473E-06 1.110E-01 Clb_2_2 -- 5.155E-05 1.726E-05 5.247E-01 1.286E-04 7.126E-06 1.382E-01 Clb_2_3 -- 5.078E-05 1.838E-05 7.906E-01 8.472E-05 7.422E-06 1.462E-01 Clb_2_4 -- 5.210E-05 3.176E-05 5.148E-01 4.865E-05 7.677E-06 1.476E-01 Clb_2_5 -- 5.451E-05 1.990E-05 9.642E-01 5.736E-05 1.257E-05 2.306E-01 Clb_2_6 -- 5.445E-05 2.035E-05 9.930E-01 5.074E-05 1.146E-05 2.102E-01 Clb_2_7 -- 5.520E-05 2.560E-05 8.775E-01 7.829E-05 1.148E-05 2.081E-01 Clb_2_8 -- 5.355E-05 1.911E-05 8.601E-01 3.387E-05 1.271E-05 2.375E-01 Clb_2_9 -- 5.615E-05 1.179E-04 8.682E-01 5.306E-04 1.181E-05 2.089E-01

178

Error Sample ID Mineral Location 234U/238U 232Th/238U 230Th/232Th 231Pa/235U 230Th/238U 230Th/234U Clb21-1 Autunite Colibri 5.828E-07 4.908E-07 1.144E+00 2.932E-06 4.114E-07 8.165E-03 Clb21-2 -- 4.786E-07 9.728E-07 6.046E-01 5.885E-06 5.697E-07 9.849E-03 Clb21-3 -- Clb21-4 -- 3.887E-07 3.133E-07 3.240E-01 3.874E-06 2.331E-07 3.991E-03 Clb21-5 -- 2.824E-07 3.824E-07 2.504E-01 5.173E-06 4.115E-07 7.094E-03 Clb21-6 -- 7.268E-07 1.418E-06 6.289E-02 5.326E-06 4.810E-07 7.813E-03 Clb21-7 -- 4.121E-07 1.313E-06 1.670E-01 3.938E-06 4.036E-07 7.406E-03 Clb21-8 -- 4.755E-07 8.825E-07 9.607E-02 5.135E-06 3.875E-07 6.982E-03 Clb21-9 -- 5.798E-07 6.762E-06 1.179E-01 1.685E-05 3.822E-07 7.176E-03 Clb21-10 -- 3.840E-07 6.040E-07 3.620E-01 7.250E-06 3.550E-07 6.690E-03

Clb_2_1 Autunite Colibri 6.462E-06 1.936E-06 5.910E-02 2.158E-05 3.186E-07 1.299E-02 Clb_2_2 -- 1.778E-06 3.901E-06 7.394E-02 5.957E-05 2.891E-07 3.837E-03 Clb_2_3 -- 3.576E-07 8.506E-06 1.289E-01 6.467E-05 4.279E-07 8.482E-03 Clb_2_4 -- 8.233E-07 1.071E-05 9.146E-02 1.470E-05 3.062E-07 5.817E-03 Clb_2_5 -- 1.837E-07 3.730E-06 1.311E-01 1.261E-05 3.199E-07 5.698E-03 Clb_2_6 -- 2.493E-07 4.108E-06 1.574E-01 8.302E-06 3.428E-07 5.950E-03 Clb_2_7 -- 5.962E-07 5.586E-06 1.437E-01 2.100E-05 3.840E-07 6.941E-03 Clb_2_8 -- 3.941E-07 2.499E-06 9.211E-02 4.459E-06 1.488E-07 2.769E-03 Clb_2_9 -- 1.169E-06 7.155E-05 3.200E-01 3.949E-04 6.932E-07 1.196E-02

179

Activity ratio Sample Mineral Location [234U/238U] [232Th/238U] [230Th/232Th] [231Pa/235U] [230Th/238U] [230Th/234U] ID Clb21-1 Autunite Colibri 9.661E-01 7.941E-07 8.952E+05 4.755E-01 3.724E-01 3.868E-01 Clb21-2 -- 1.018E+00 1.075E-06 6.560E+05 6.929E-01 4.665E-01 4.568E-01 Clb21-3 -- 0.000E+00 Clb21-4 -- 1.002E+00 9.662E-07 5.357E+05 5.715E-01 4.211E-01 4.198E-01 Clb21-5 -- 1.037E+00 1.341E-06 4.094E+05 6.709E-01 4.677E-01 4.502E-01 Clb21-6 -- 9.844E-01 4.094E-06 1.226E+05 6.837E-01 4.311E-01 4.346E-01 Clb21-7 -- 9.825E-01 3.847E-06 1.555E+05 7.300E-01 4.496E-01 4.572E-01 Clb21-8 -- 9.700E-01 2.931E-06 1.665E+05 7.437E-01 4.163E-01 4.285E-01 Clb21-9 -- 9.250E-01 8.671E-06 8.902E+04 1.416E+00 3.620E-01 3.904E-01 Clb21-10 -- 9.808E-01 1.078E-06 5.397E+05 8.825E-01 4.360E-01 4.448E-01

Clb_2_1 Autunite Colibri 1.130E+00 4.216E-06 1.052E+05 1.047E+00 3.837E-01 3.624E-01 Clb_2_2 -- 9.362E-01 5.507E-06 9.750E+04 2.762E+00 4.224E-01 4.511E-01 Clb_2_3 -- 9.222E-01 5.863E-06 1.469E+05 1.820E+00 4.399E-01 4.773E-01 Clb_2_4 -- 9.462E-01 1.013E-05 9.566E+04 1.045E+00 4.551E-01 4.816E-01 Clb_2_5 -- 9.901E-01 6.346E-06 1.792E+05 1.232E+00 7.453E-01 7.524E-01 Clb_2_6 -- 9.889E-01 6.492E-06 1.845E+05 1.090E+00 6.790E-01 6.860E-01 Clb_2_7 -- 1.003E+00 8.166E-06 1.631E+05 1.682E+00 6.807E-01 6.792E-01 Clb_2_8 -- 9.727E-01 6.094E-06 1.598E+05 7.276E-01 7.536E-01 7.749E-01 Clb_2_9 -- 1.020E+00 3.759E-05 1.613E+05 1.140E+01 6.998E-01 6.819E-01

180

Ratio Sample ID Mineral Location 234U/238U 232Th/238U 230Th/232Th 231Pa/235U 230Th/238U 230Th/234U Nuevo Mac207-1 Autunite 5.655E-05 3.041E-05 3.430E-01 3.747E-05 9.420E-06 1.665E-01 Corani Mac207-2 -- 5.608E-05 2.638E-05 3.870E-01 2.781E-05 9.539E-06 1.700E-01 Mac207-3 -- 5.655E-05 1.686E-05 6.166E-01 3.791E-05 9.808E-06 1.733E-01 Mac207-4 -- 5.690E-05 1.721E-05 8.535E-01 3.728E-05 1.073E-05 1.888E-01 Mac207-5 -- 5.652E-05 1.052E-05 1.177E+00 3.793E-05 1.020E-05 1.804E-01 Mac207-6 -- 5.809E-05 1.040E-05 1.083E+00 3.488E-05 1.071E-05 1.843E-01 Mac207-7 -- 5.767E-05 3.177E-05 3.647E-01 3.540E-05 1.102E-05 1.909E-01

Nuevo CR-weeksite 1 Weeksite 5.653E-05 2.779E-05 3.860E-01 9.294E-05 5.475E-06 9.685E-02 Corani CR-weeksite 2 -- 5.631E-05 5.343E-05 1.684E+00 2.243E-04 6.513E-06 1.167E-01 CR-weeksite 3 -- 5.423E-05 1.536E-05 5.329E-01 6.230E-05 5.519E-06 1.019E-01 CR-weeksite 4 -- 5.673E-05 1.265E-05 2.801E-01 2.104E-04 3.363E-06 5.884E-02

Mac 206-1 Autunite Tantamaco 5.754E-05 1.075E-06 1.086E+01 3.185E-05 1.011E-05 1.756E-01 Mac 206-2 -- 5.666E-05 3.863E-06 2.968E+00 3.576E-05 9.209E-06 1.625E-01 Mac 206-3 -- 5.778E-05 1.025E-06 1.222E+01 3.430E-05 9.922E-06 1.717E-01 Mac 206-4 -- 5.852E-05 8.672E-07 1.090E+01 7.753E-05 9.063E-06 1.548E-01 Mac 206-5 -- 5.742E-05 8.510E-07 1.177E+01 3.557E-05 9.482E-06 1.646E-01 Mac 206-6 -- 5.912E-05 1.020E-06 1.104E+01 3.347E-05 1.093E-05 1.844E-01 Mac 206-7 -- 5.787E-05 9.974E-07 2.156E+01 1.126E-04 1.723E-05 2.978E-01 Mac 206-8 -- 5.657E-05 3.522E-06 3.723E+00 2.850E-05 9.832E-06 1.736E-01 Mac 206-9 -- 5.738E-05 1.336E-06 1.067E+01 2.878E-05 1.047E-05 1.824E-01 Mac 206-10 -- 5.683E-05 1.657E-06 9.457E+00 3.067E-05 1.086E-05 1.909E-01

181

Error Sample ID Mineral Location 234U/238U 232Th/238U 230Th/232Th 231Pa/235U 230Th/238U 230Th/234U Nuevo Mac207-1 Autunite Corani 1.421E-07 2.324E-06 2.424E-02 2.817E-06 7.359E-08 1.265E-03 Mac207-2 -- 2.270E-07 1.540E-06 2.440E-02 3.040E-06 1.110E-07 2.050E-03 Mac207-3 -- 1.730E-07 1.110E-06 3.050E-02 4.830E-06 5.250E-08 8.750E-04 Mac207-4 -- 5.890E-07 1.470E-06 1.710E-01 4.080E-06 8.520E-08 2.140E-03 Mac207-5 -- 2.010E-07 9.990E-07 1.310E-01 4.200E-06 1.390E-07 2.270E-03 Mac207-6 -- 2.010E-07 5.280E-07 5.760E-02 1.590E-06 7.180E-08 1.190E-03 Mac207-7 -- 7.930E-08 1.810E-06 1.760E-02 2.530E-06 9.020E-08 1.470E-03

Nuevo CR-weeksite 1 Weeksite Corani 1.200E-06 6.880E-06 1.070E-01 2.660E-05 3.140E-07 5.210E-03 CR-weeksite 2 -- 8.020E-07 3.270E-05 1.170E+00 1.680E-04 1.110E-06 2.100E-02 CR-weeksite 3 -- 5.890E-07 3.210E-06 9.030E-02 2.060E-05 2.040E-07 4.140E-03 CR-weeksite 4 -- 8.450E-07 1.170E-06 1.550E-01 1.990E-04 1.630E-06 2.780E-02

Mac 206-1 Autunite Tantamaco 2.070E-07 1.130E-07 8.380E-01 1.800E-06 5.600E-08 7.450E-04 Mac 206-2 -- 1.670E-07 4.660E-07 3.470E-01 3.890E-06 8.980E-08 1.630E-03 Mac 206-3 -- 9.870E-08 9.720E-08 1.690E+00 2.510E-06 7.490E-08 1.320E-03 Mac 206-4 -- 3.290E-07 5.000E-08 5.920E-01 2.080E-05 2.990E-07 5.090E-03 Mac 206-5 -- 7.320E-07 4.560E-08 7.040E-01 3.470E-06 2.050E-07 2.950E-03 Mac 206-6 -- 6.860E-07 4.240E-08 5.450E-01 1.910E-06 3.050E-07 5.040E-03 Mac 206-7 -- 1.730E-07 1.120E-07 2.510E+00 1.170E-05 7.300E-07 1.280E-02 Mac 206-8 -- 2.870E-07 4.240E-07 5.490E-01 3.220E-06 1.610E-07 2.310E-03 Mac 206-9 -- 7.810E-08 1.570E-07 1.790E+00 1.560E-06 1.880E-07 3.240E-03 Mac 206-10 -- 1.570E-07 2.220E-07 1.560E+00 2.610E-06 3.180E-07 5.400E-03

182

Activity

ratio

Sample ID Mineral Location [232Th/238U] [230Th/232Th] [231Pa/235U] [230Th/238U] [230Th/234U] [234U/238U] Nuevo Mac207-1 Autunite 1.027E+00 9.700E-06 6.374E+04 8.050E-01 5.583E-01 5.434E-01 Corani Mac207-2 -- 1.019E+00 8.415E-06 7.191E+04 5.975E-01 5.654E-01 5.549E-01 Mac207-3 -- 1.027E+00 5.379E-06 1.146E+05 8.146E-01 5.813E-01 5.657E-01 Mac207-4 -- 1.033E+00 5.490E-06 1.586E+05 8.011E-01 6.361E-01 6.162E-01 Mac207-5 -- 1.027E+00 3.357E-06 2.188E+05 8.150E-01 6.048E-01 5.888E-01 Mac207-6 -- 1.055E+00 3.318E-06 2.012E+05 7.494E-01 6.349E-01 6.015E-01 Mac207-7 -- 1.047E+00 1.013E-05 6.778E+04 7.606E-01 6.530E-01 6.230E-01

Nuevo CR-weeksite 1 Weeksite 1.027E+00 8.863E-06 7.172E+04 1.997E+00 3.245E-01 3.161E-01 Corani CR-weeksite 2 -- 1.023E+00 1.704E-05 3.130E+05 4.819E+00 3.860E-01 3.808E-01 CR-weeksite 3 -- 9.849E-01 4.900E-06 9.903E+04 1.339E+00 3.271E-01 3.327E-01 CR-weeksite 4 -- 1.030E+00 4.035E-06 5.205E+04 4.520E+00 1.993E-01 1.920E-01

Mac 206-1 Autunite Tantamaco 1.045E+00 3.430E-07 2.017E+06 6.843E-01 5.992E-01 5.731E-01 Mac 206-2 -- 1.029E+00 1.232E-06 5.516E+05 7.683E-01 5.458E-01 5.302E-01 Mac 206-3 -- 1.049E+00 3.271E-07 2.272E+06 7.369E-01 5.881E-01 5.602E-01 Mac 206-4 -- 1.063E+00 2.766E-07 2.026E+06 1.666E+00 5.372E-01 5.052E-01 Mac 206-5 -- 1.043E+00 2.715E-07 2.186E+06 7.642E-01 5.621E-01 5.372E-01 Mac 206-6 -- 1.074E+00 3.253E-07 2.051E+06 7.190E-01 6.477E-01 6.016E-01 Mac 206-7 -- 1.051E+00 3.182E-07 4.007E+06 2.419E+00 1.021E+00 9.717E-01 Mac 206-8 -- 1.027E+00 1.123E-06 6.917E+05 6.123E-01 5.828E-01 5.666E-01 Mac 206-9 -- 1.042E+00 4.263E-07 1.984E+06 6.184E-01 6.207E-01 5.953E-01 Mac 206-10 -- 1.032E+00 5.286E-07 1.757E+06 6.588E-01 6.437E-01 6.230E-01

183 Ratio Sample ID Mineral Location 234U/238U 232Th/238U 230Th/232Th 231Pa/235U 230Th/238U 230Th/234U Nuevo Mac207_7 Autunite 5.362E-05 2.698E-05 6.957E-01 4.436E-05 1.703E-05 3.176E-01 Corani Mac207_8 -- 5.219E-05 2.334E-05 7.355E-01 4.026E-05 1.585E-05 3.037E-01 Mac207_12 -- 5.077E-05 2.379E-05 6.747E-01 4.791E-05 1.468E-05 2.957E-01

Mac_206_1 Autunite Tantamaco 5.169E-05 4.684E-06 2.469E+00 3.587E-05 1.021E-05 1.977E-01 Mac_206_2 -- 5.390E-05 3.095E-05 2.947E+00 6.047E-04 1.190E-05 2.188E-01 Mac_206_3 -- 5.435E-05 2.417E-06 6.239E+00 3.870E-05 1.076E-05 1.980E-01

Chilcuno_1 Autunite Chilcuno 5.392E-05 1.030E-05 1.673E+00 3.610E-05 1.352E-05 2.480E-01 Chilcuno_3 -- 5.633E-05 5.226E-05 7.696E-01 4.036E-05 1.391E-05 2.472E-01 Chilcuno_2 -- 5.303E-05 3.653E-05 5.973E-01 3.485E-05 1.393E-05 2.624E-01 Chilcuni_4 -- 5.366E-05 4.658E-05 4.460E-01 3.273E-05 1.301E-05 2.423E-01 Chilcuno_5 -- 5.301E-05 4.435E-05 4.840E-01 5.381E-05 1.429E-05 2.700E-01 Chilcuno_6 -- 5.247E-05 9.248E-05 3.154E-01 5.617E-05 1.440E-05 2.743E-01 Chilcuno_7 -- 5.295E-05 3.611E-05 5.627E-01 5.113E-05 1.303E-05 2.464E-01 Chilcuno_8 -- 5.379E-05 3.313E-05 8.428E-01 2.802E-05 1.343E-05 2.496E-01 Chilcuno_10 -- 5.273E-05 1.486E-05 1.321E+00 3.279E-05 1.373E-05 2.604E-01 Chilcuno_11 -- 5.316E-05 1.591E-05 1.008E+00 4.528E-05 1.330E-05 2.502E-01 Chilcuno_12 -- 5.205E-05 2.045E-05 9.164E-01 4.288E-05 1.323E-05 2.540E-01 Chilcuno_13 -- 5.396E-05 2.197E-05 5.984E-01 3.620E-05 1.161E-05 2.152E-01

184 Error Sample ID Mineral Location 234U/238U 232Th/238U 230Th/232Th 231Pa/235U 230Th/238U 230Th/234U Nuevo Mac207_7 Autunite Corani 2.939E-07 1.929E-06 4.634E-02 4.368E-06 2.436E-07 4.970E-03 Mac207_8 -- 2.939E-07 1.808E-06 5.072E-02 2.349E-06 9.587E-08 2.362E-03 Mac207_12 -- 1.294E-07 1.238E-06 4.893E-02 3.198E-06 1.493E-07 3.300E-03

Mac_206_1 Autunite Tantamaco 3.727E-07 4.140E-07 1.924E-01 3.193E-06 1.253E-07 3.110E-03 Mac_206_2 -- 7.825E-07 2.606E-05 4.643E-01 4.209E-04 8.429E-07 1.166E-02 Mac_206_3 -- 3.891E-07 3.026E-07 9.913E-01 3.317E-06 1.352E-07 2.019E-03

Chilcuno_1 Autunite Chilcuno 1.646E-06 1.156E-06 4.244E-01 3.965E-06 8.167E-07 8.064E-03 Chilcuno_3 -- 7.866E-07 1.785E-05 1.217E-01 1.350E-05 5.753E-07 9.997E-03 Chilcuno_2 -- 5.242E-07 4.836E-06 2.141E-01 7.742E-06 3.643E-07 5.981E-03 Chilcuni_4 -- 3.776E-07 1.077E-05 8.638E-02 6.152E-06 3.952E-07 6.648E-03 Chilcuno_5 -- 1.022E-06 9.144E-06 8.275E-02 1.266E-05 2.891E-07 5.454E-03 Chilcuno_6 -- 2.206E-07 3.455E-05 6.153E-02 9.209E-06 3.647E-07 6.700E-03 Chilcuno_7 -- 7.155E-07 8.119E-06 1.666E-01 6.713E-06 4.627E-07 9.470E-03 Chilcuno_8 -- 8.079E-07 6.923E-06 3.148E-01 6.811E-06 4.697E-07 7.788E-03 Chilcuno_10 -- 2.965E-07 3.016E-06 1.913E-01 3.292E-06 3.357E-07 6.279E-03 Chilcuno_11 -- 2.584E-07 2.477E-06 8.346E-02 1.050E-05 4.023E-07 7.367E-03 Chilcuno_12 -- 3.852E-07 3.234E-06 1.321E-01 7.190E-06 3.842E-07 6.834E-03

185 Activity

ratio

Sample ID Mineral Location [232Th/238U] [230Th/232Th] [231Pa/235U] [230Th/238U] [230Th/234U] [234U/238U] Nuevo Mac207_7 Autunite 9.739E-01 8.605E-06 1.293E+05 9.531E-01 1.010E+00 1.036E+00 Corani Mac207_8 -- 9.479E-01 7.444E-06 1.367E+05 8.649E-01 9.395E-01 9.910E-01 Mac207_12 -- 9.222E-01 7.589E-06 1.254E+05 1.029E+00 8.704E-01 9.651E-01

Mac_206_1 Autunite Tantamaco 9.388E-01 1.494E-06 4.588E+05 7.708E-01 6.049E-01 6.451E-01 Mac_206_2 -- 9.789E-01 9.874E-06 5.477E+05 1.299E+01 7.051E-01 7.139E-01 Mac_206_3 -- 9.871E-01 7.710E-07 1.159E+06 8.315E-01 6.379E-01 6.461E-01

Chilcuno_1 Autunite Chilcuno 9.793E-01 3.286E-06 3.108E+05 7.757E-01 8.016E-01 8.093E-01 Chilcuno_3 -- 1.023E+00 1.667E-05 1.430E+05 8.672E-01 8.243E-01 8.066E-01 Chilcuno_2 -- 9.631E-01 1.165E-05 1.110E+05 7.488E-01 8.254E-01 8.565E-01 Chilcuni_4 -- 9.745E-01 1.486E-05 8.288E+04 7.031E-01 7.712E-01 7.908E-01 Chilcuno_5 -- 9.628E-01 1.415E-05 8.994E+04 1.156E+00 8.469E-01 8.813E-01 Chilcuno_6 -- 9.531E-01 2.950E-05 5.861E+04 1.207E+00 8.533E-01 8.951E-01 Chilcuno_7 -- 9.617E-01 1.152E-05 1.046E+05 1.099E+00 7.721E-01 8.041E-01 Chilcuno_8 -- 9.770E-01 1.057E-05 1.566E+05 6.019E-01 7.963E-01 8.147E-01 Chilcuno_10 -- 9.576E-01 4.739E-06 2.456E+05 7.045E-01 8.140E-01 8.500E-01 Chilcuno_11 -- 9.656E-01 5.076E-06 1.873E+05 9.728E-01 7.882E-01 8.165E-01 Chilcuno_12 -- 9.453E-01 6.523E-06 1.703E+05 9.213E-01 7.841E-01 8.289E-01 Chilcuno_13 -- 9.800E-01 7.008E-06 1.112E+05 7.777E-01 6.882E-01 7.025E-01

186 Ratio Sample ID Mineral Location 234U/238U 232Th/238U 230Th/232Th 231Pa/235U 230Th/238U 230Th/234U Chi_6_2 Autunite Chilcuno 5.237E-05 6.713E-06 1.418E+00 1.327E-05 8.268E-06 1.575E-01 Chi_6_3 -- 5.062E-05 3.211E-06 3.163E+00 2.526E-05 8.818E-06 1.736E-01 Chi_6_4 -- 5.169E-05 2.518E-06 3.009E+00 2.362E-05 6.045E-06 1.170E-01 Chi_6_5 -- 5.099E-05 4.679E-06 2.232E+00 2.569E-05 9.334E-06 1.830E-01 Chi_6_6 -- 5.110E-05 1.010E-05 1.399E+00 6.089E-05 8.500E-06 1.666E-01 Chi_6_7 -- Chi_6_8 -- 5.451E-05 3.115E-05 3.817E-01 3.541E-05 9.504E-06 1.743E-01 Chi_6_9 -- 5.379E-05 2.398E-05 5.193E-01 3.811E-05 9.559E-06 1.776E-01 Chi_6_10 -- 5.379E-05 6.545E-06 3.780E+00 3.114E-05 9.702E-06 1.804E-01 Chi_6_11 -- 5.423E-05 2.307E-05 5.924E-01 4.569E-05 8.668E-06 1.604E-01 Chi_6_12 -- 5.435E-05 5.091E-05 1.949E-01 2.829E-05 9.104E-06 1.676E-01

Pinocho2_1 Autunite Pinocho 5.536E-05 6.281E-06 4.257E+00 6.046E-05 1.540E-05 2.782E-01 Pinocho2_2 -- 5.208E-05 3.807E-06 5.546E+00 5.680E-05 1.512E-05 2.903E-01 Pinocho2_3 -- 5.399E-05 2.745E-06 9.122E+00 4.405E-05 1.537E-05 2.849E-01 Pinicho2_4 -- 5.430E-05 5.608E-06 3.928E+00 6.962E-05 1.589E-05 2.927E-01 Pinocho2_6 -- 5.350E-05 1.478E-06 1.653E+01 4.143E-05 1.488E-05 2.781E-01 Pinocho2_7 -- 5.333E-05 4.553E-06 9.124E+00 2.956E-05 1.592E-05 2.982E-01 Pinocho2_8 -- 5.282E-05 7.979E-06 6.102E+00 5.389E-05 1.523E-05 2.883E-01 Pinocho2_9 -- 5.370E-05 1.321E-05 4.231E+00 6.439E-05 1.565E-05 2.924E-01 Pinocho2_11 -- 5.315E-05 2.055E-06 1.880E+01 4.179E-05 1.539E-05 2.894E-01

187 Error Sample ID Mineral Location 234U/238U 232Th/238U 230Th/232Th 231Pa/235U 230Th/238U 230Th/234U Chi_6_2 Autunite Chilcuno 1.168E-06 7.010E-07 1.097E-01 2.179E-06 1.283E-07 2.697E-03 Chi_6_3 -- 6.969E-07 3.353E-07 2.437E-01 2.352E-06 1.345E-07 1.513E-03 Chi_6_4 -- 2.309E-07 4.189E-07 3.065E-01 5.684E-06 2.012E-07 4.069E-03 Chi_6_5 -- 1.339E-07 3.736E-07 1.733E-01 2.621E-06 9.375E-08 1.752E-03 Chi_6_6 -- 2.226E-07 3.134E-06 1.584E-01 3.282E-05 3.722E-07 7.445E-03 Chi_6_7 -- Chi_6_8 -- 1.652E-07 2.821E-06 4.928E-02 2.916E-06 1.094E-07 1.982E-03 Chi_6_9 -- 2.196E-07 5.180E-06 6.007E-02 5.919E-06 2.155E-07 3.721E-03 Chi_6_10 -- 9.903E-08 8.576E-07 1.366E+00 3.658E-06 5.987E-08 1.056E-03 Chi_6_11 -- 5.897E-07 3.433E-06 1.086E-01 1.026E-05 1.570E-07 3.830E-03 Chi_6_12 -- 4.781E-07 3.677E-06 1.358E-02 4.451E-06 1.598E-07 2.938E-03

Pinocho2_1 Autunite Pinocho 5.057E-07 1.918E-06 7.999E-01 1.264E-05 1.972E-07 3.221E-03 Pinocho2_2 -- 3.267E-07 7.290E-07 8.616E-01 1.879E-05 1.845E-07 3.623E-03 Pinocho2_3 -- 4.571E-07 4.094E-07 1.589E+00 5.321E-06 1.784E-07 3.826E-03 Pinicho2_4 -- 3.261E-07 7.110E-07 6.151E-01 1.641E-05 1.482E-07 3.390E-03 Pinocho2_6 -- 5.561E-07 3.429E-07 5.045E+00 9.114E-06 4.331E-07 7.544E-03 Pinocho2_7 -- 3.463E-07 1.547E-06 2.347E+00 8.918E-06 3.313E-07 5.532E-03 Pinocho2_8 -- 4.148E-07 3.680E-06 1.205E+00 1.214E-05 4.133E-07 7.806E-03 Pinocho2_9 -- 6.341E-07 6.916E-06 1.126E+00 1.828E-05 4.856E-07 9.983E-03 Pinocho2_11 -- 5.324E-07 6.315E-07 4.175E+00 7.416E-06 2.008E-07 3.196E-03

188 Activity ratio Sample ID Mineral Location [234U/238U] [232Th/238U] [230Th/232Th] [231Pa/235U] [230Th/238U] [230Th/234U] Chi_6_2 Autunite Chilcuno 9.512E-01 2.141E-06 2.635E+05 2.850E-01 4.900E-01 5.141E-01 Chi_6_3 -- 9.194E-01 1.024E-06 5.878E+05 5.426E-01 5.227E-01 5.667E-01 Chi_6_4 -- 9.389E-01 8.032E-07 5.591E+05 5.075E-01 3.583E-01 3.819E-01 Chi_6_5 -- 9.261E-01 1.493E-06 4.147E+05 5.519E-01 5.532E-01 5.974E-01 Chi_6_6 -- 9.280E-01 3.222E-06 2.599E+05 1.308E+00 5.038E-01 5.436E-01 Chi_6_7 -- 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 Chi_6_8 -- 9.900E-01 9.937E-06 7.092E+04 7.607E-01 5.633E-01 5.690E-01 Chi_6_9 -- 9.770E-01 7.648E-06 9.650E+04 8.187E-01 5.666E-01 5.797E-01 Chi_6_10 -- 9.769E-01 2.088E-06 7.024E+05 6.690E-01 5.750E-01 5.886E-01 Chi_6_11 -- 9.849E-01 7.359E-06 1.101E+05 9.816E-01 5.138E-01 5.234E-01 Chi_6_12 -- 9.871E-01 1.624E-05 3.622E+04 6.078E-01 5.396E-01 5.470E-01

Pinocho2_1 Autunite Pinocho 1.006E+00 2.004E-06 7.910E+05 1.299E+00 9.131E-01 9.078E-01 Pinocho2_2 -- 9.459E-01 1.214E-06 1.031E+06 1.220E+00 8.963E-01 9.473E-01 Pinocho2_3 -- 9.805E-01 8.756E-07 1.695E+06 9.464E-01 9.110E-01 9.297E-01 Pinicho2_4 -- 9.862E-01 1.789E-06 7.298E+05 1.496E+00 9.417E-01 9.551E-01 Pinocho2_6 -- 9.716E-01 4.715E-07 3.071E+06 8.901E-01 8.822E-01 9.076E-01 Pinocho2_7 -- 9.686E-01 1.452E-06 1.695E+06 6.352E-01 9.435E-01 9.733E-01 Pinocho2_8 -- 9.593E-01 2.545E-06 1.134E+06 1.158E+00 9.025E-01 9.408E-01 Pinocho2_9 -- 9.752E-01 4.214E-06 7.863E+05 1.383E+00 9.274E-01 9.542E-01 Pinocho2_11 -- 9.654E-01 6.554E-07 3.494E+06 8.979E-01 9.121E-01 9.445E-01

189 Ratio Sample ID Mineral Location 234U/238U 232Th/238U 230Th/232Th 231Pa/235U 230Th/238U 230Th/234U Pi_2_1 Autunite Pinocho 5.275E-05 3.867E-06 5.713E+00 7.386E-05 1.177E-05 2.232E-01 Pi_2_2 -- 5.520E-05 3.031E-06 7.115E+00 3.347E-05 1.165E-05 2.115E-01 Pi_2_3 -- 5.547E-05 7.819E-06 5.301E+00 1.116E-04 1.203E-05 2.170E-01 Pi_2_4 -- 5.690E-05 1.006E-05 6.027E+00 1.741E-04 1.392E-05 2.438E-01 Pi_2_5 -- 5.734E-05 6.153E-06 4.534E+00 5.497E-05 1.211E-05 2.126E-01 Pi_2_6 -- 5.303E-05 1.400E-05 2.113E+00 9.450E-05 1.289E-05 2.442E-01 Pi_2_7 -- 5.254E-05 3.838E-06 4.029E+00 5.155E-05 1.179E-05 2.245E-01 Pi_2_8 -- 5.176E-05 3.316E-06 4.624E+00 1.073E-04 1.081E-05 2.089E-01

Tuturumani4_1 Autunite Tuturumani 5.239E-05 1.789E-05 1.501E+00 5.041E-05 1.413E-05 2.696E-01 Tuturumani4_2 -- 5.108E-05 2.336E-05 8.862E-01 5.129E-05 1.484E-05 2.896E-01 Tuturumani4_3 -- 5.201E-05 3.736E-05 7.193E-01 4.993E-05 1.541E-05 2.958E-01 Tuturumani4_4 -- 5.114E-05 2.037E-05 1.080E+00 5.075E-05 1.417E-05 2.766E-01 Tuturumani4_5 -- 5.116E-05 2.410E-05 1.162E+00 5.160E-05 1.462E-05 2.853E-01 Tuturumani4_6 -- 5.211E-05 4.141E-05 6.638E-01 5.511E-05 1.569E-05 3.008E-01 Tuturumani4_7 -- 5.169E-05 1.383E-05 1.732E+00 4.842E-05 1.466E-05 2.834E-01 Tuturumani4_8 -- 5.161E-05 6.679E-05 5.858E-01 4.964E-05 1.494E-05 2.893E-01 Tuturumani4_9 -- 5.141E-05 2.312E-05 1.580E+00 5.127E-05 1.472E-05 2.859E-01 Tuturumani4_10 -- 5.129E-05 1.184E-05 2.491E+00 6.640E-05 1.408E-05 2.742E-01 Tuturumani4_11 -- 5.114E-05 8.443E-06 2.936E+00 5.763E-05 1.413E-05 2.759E-01

190 Error Sample ID Mineral Location 234U/238U 232Th/238U 230Th/232Th 231Pa/235U 230Th/238U 230Th/234U Pi_2_1 Autunite Pinocho 2.216E-07 1.260E-06 6.768E-01 2.274E-05 2.757E-07 5.446E-03 Pi_2_2 -- 7.345E-07 4.923E-07 2.529E+00 4.031E-06 2.371E-07 4.833E-03 Pi_2_3 -- 6.526E-07 2.439E-06 1.415E+00 4.028E-05 1.639E-07 3.164E-03 Pi_2_4 -- 9.723E-07 5.372E-06 1.081E+00 1.132E-04 1.207E-06 1.976E-02 Pi_2_5 -- 1.365E-06 1.739E-06 8.679E-01 1.096E-05 2.255E-07 5.119E-03 Pi_2_6 -- 5.432E-07 4.296E-06 3.926E-01 3.313E-05 1.038E-06 2.121E-02 Pi_2_7 -- 4.319E-07 5.756E-07 4.180E-01 9.416E-06 1.120E-07 2.533E-03 Pi_2_8 -- 2.696E-07 6.925E-07 4.953E-01 3.957E-05 2.164E-07 4.084E-03

Tuturumani4_1 Autunite Tuturumani 5.733E-07 4.943E-06 2.359E-01 3.780E-06 2.722E-07 4.815E-03 Tuturumani4_2 -- 4.723E-07 3.717E-06 1.195E-01 4.307E-06 3.462E-07 4.933E-03 Tuturumani4_3 -- 4.172E-07 9.986E-06 7.889E-02 5.880E-06 3.271E-07 5.489E-03 Tuturumani4_4 -- 3.449E-07 6.285E-06 1.065E-01 4.244E-06 2.710E-07 4.426E-03 Tuturumani4_5 -- 2.929E-07 6.935E-06 1.506E-01 3.746E-06 2.968E-07 4.699E-03 Tuturumani4_6 -- 1.997E-07 1.087E-05 7.702E-02 6.157E-06 2.463E-07 4.200E-03 Tuturumani4_7 -- 3.223E-07 2.586E-06 2.907E-01 5.274E-06 2.349E-07 4.060E-03 Tuturumani4_8 -- 3.375E-07 2.485E-05 8.899E-02 5.824E-06 2.184E-07 3.715E-03 Tuturumani4_9 -- 2.978E-07 4.273E-06 4.219E-01 3.282E-06 3.589E-07 6.244E-03 Tuturumani4_10 -- 5.591E-07 2.047E-06 5.940E-01 9.436E-06 3.268E-07 5.321E-03 Tuturumani4_11 -- 4.164E-07 1.769E-06 4.508E-01 6.889E-06 3.033E-07 5.139E-03

191 Activity ratio Sample ID Mineral Location [234U/238U] [232Th/238U] [230Th/232Th] [231Pa/235U] [230Th/238U] [230Th/234U] Pi_2_1 Autunite Pinocho 9.581E-01 1.233E-06 1.062E+06 1.587E+00 6.976E-01 7.283E-01 Pi_2_2 -- 1.003E+00 9.669E-07 1.322E+06 7.191E-01 6.906E-01 6.901E-01 Pi_2_3 -- 1.007E+00 2.494E-06 9.851E+05 2.398E+00 7.132E-01 7.083E-01 Pi_2_4 -- 1.033E+00 3.209E-06 1.120E+06 3.741E+00 8.251E-01 7.956E-01 Pi_2_5 -- 1.041E+00 1.963E-06 8.425E+05 1.181E+00 7.179E-01 6.937E-01 Pi_2_6 -- 9.631E-01 4.466E-06 3.927E+05 2.030E+00 7.640E-01 7.970E-01 Pi_2_7 -- 9.542E-01 1.224E-06 7.486E+05 1.108E+00 6.986E-01 7.326E-01 Pi_2_8 -- 9.401E-01 1.058E-06 8.592E+05 2.306E+00 6.408E-01 6.816E-01

Tuturumani4_1 Autunite Tuturumani 9.515E-01 5.706E-06 2.789E+05 1.083E+00 8.378E-01 8.799E-01 Tuturumani4_2 -- 9.278E-01 7.452E-06 1.647E+05 1.102E+00 8.795E-01 9.451E-01 Tuturumani4_3 -- 9.447E-01 1.192E-05 1.337E+05 1.073E+00 9.132E-01 9.652E-01 Tuturumani4_4 -- 9.288E-01 6.498E-06 2.008E+05 1.090E+00 8.400E-01 9.025E-01 Tuturumani4_5 -- 9.291E-01 7.687E-06 2.159E+05 1.109E+00 8.664E-01 9.311E-01 Tuturumani4_6 -- 9.465E-01 1.321E-05 1.233E+05 1.184E+00 9.299E-01 9.817E-01 Tuturumani4_7 -- 9.389E-01 4.411E-06 3.219E+05 1.040E+00 8.688E-01 9.249E-01 Tuturumani4_8 -- 9.375E-01 2.130E-05 1.089E+05 1.066E+00 8.854E-01 9.442E-01 Tuturumani4_9 -- 9.338E-01 7.376E-06 2.935E+05 1.102E+00 8.726E-01 9.331E-01 Tuturumani4_10 -- 9.316E-01 3.777E-06 4.630E+05 1.427E+00 8.348E-01 8.948E-01 Tuturumani4_11 -- 9.289E-01 2.693E-06 5.455E+05 1.238E+00 8.376E-01 9.003E-01

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