Lithogeochemistry, Hydrothermal Alteration, Mineralization, Fluid Inclusion and Sulfur Isotope Study of the Halo Porphyry Copper

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Lithogeochemistry, Hydrothermal Alteration, Mineralization, Fluid Inclusion and Sulfur Isotope Study of the Halo Porphyry Copper- Molybdenum Prospect, Northeast Cambodia

シーン, セライソカ

https://doi.org/10.15017/2534418

出版情報：九州大学, 2019, 博士（工学）, 課程博士バージョン：権利関係：

Lithogeochemistry, Hydrothermal Alteration, Mineralization, Fluid Inclusion and Sulfur Isotope Study of the Halo Porphyry Copper-

Molybdenum Prospect, Northeast Cambodia

SEANG SIRISOKHA

2019

Lithogeochemistry, Hydrothermal Alteration, Mineralization, Fluid Inclusion and Sulfur Isotope Study of the Halo Porphyry Copper- Molybdenum Prospect, Northeast Cambodia

SEANG SIRISOKHA

A thesis submitted in partial fulfillment of the requirements for the degree of DOCTOR OF ENGINEERING

Department of Earth Resources Engineering Graduated School of Engineering Kyushu University, Fukuoka, Japan

Examination Committee:

Professor Koichiro Watanabe (Chairman) Professor Akira Imai Professor Kazuya Idemitsu Associate Professor Kotaro Yonezu

July, 2019 Fukuoka, Japan

Abstracts

The Halo copper-molybdenum prospect is a porphyry system in Ratanakiri province, northeastern part of Cambodia. The province has a potential for porphyry- type deposits such as porphyry copper-molybdenum (Halo prospect, China Wall prospect) and porphyry copper-molybdenum-gold (Okalla prospect). The Halo porphyry copper-molybdenum prospect lies 2km southeast of a strike slip fault trending NE-SW, known as the Phum Syarung-Dok Yong Fault corridor. The Halo prospect is hosted by intermediate to felsic intrusive and volcanic rocks. However, detailed geochemical characteristics of rocks, alteration lithogeochemistry, ore mineralization, fluid inclusion and sulfur isotope were not studied yet, which only one research was carried out on the Halo porphyry copper-molybdenite deposit, including geological mapping, termite mound geochemistry, short wave infrared (SWIR) spectroscopy on alteration mineral identification, and rock-chip geochemistry. This is the first study that focuses on the characteristics of the intrusive rocks (major elements, trace elements, and rare earth elements) to constrain petrogenesis and tectonic setting, and lithogeochemistry of intrusive and volcanic rocks to demonstrate elements transportation during hydrothermal alteration. In addition, this study also defines alteration and vein mineral paragenesis, fluid inclusion microthermometry in detail to elucidate relationships between alterations, ore mineralization and evolution of ore forming fluid. Sulfur isotope analysis was further conducted in order to understand the source of mineralized fluid at the Halo porphyry copper-molybdenum prospect.

Chapter 1 introduces the research background, location of study area, problem statement, objective of research, methodology and thesis organization.

Chapter 2 describes the regional geology, tectonic setting, deposit geology and overview on intrusive rocks and volcanic rocks in the Halo prospect. The characteristics of intrusive rocks and volcanic rocks were described on the basis of petrography. The Halo porphyry copper-molybdenum deposit, is hosted by diorite, granodiorite, granodiorite porphyry, quartz feldspar porphyry, and andesite porphyry.

Chapter 3 describes the lithogeochemistry of the intrusive rocks and volcanic rocks. The intrusive rocks and volcanic rocks in the Halo prospect, range from diorite to granite (quartz feldspar porphyry) in composition as well as dacite to trachyandesite

(andesite porphyry) in composition, respectively. They were formed in a subduction- related tectonic setting, likely a volcanic arc. Trace elements spider diagrams normalized to primitive mantle display strong enrichment in large-ion lithophile elements such as Rb, Ba and K and depletion in some high-field strength elements such as Nb and Ti, suggesting that magmas were generated in a subduction related tectonic setting. Pearce Element Ratio (PER) analysis was used in this research to identify material transfer during hydrothermal alteration. PER analysis indicates a moderate to high degree of sericite alteration of dacites, quartz feldspar porphyries, andesite porphyries and granodiorite porphyries. Moreover, three alterations in the

Halo prospect such as potassic (secondary K-feldspar and biotite), phyllic (sericite) and propylitic (epidote) alteration were identified. The potassic alteration within the quartz feldspar porphyries, andesite porphyry and granodiorite porphyry with high grad of copper ranges up to 2670ppm and molybdenum ranges up to 5297ppm. The potassic alteration zone vectoring center of the hydrothermal system may represent the locus of mineralization.

Chapter 4 documents the hydrothermal alteration, mineral paragenesis, and style of mineralization. The Halo deposit is characterized by an early potassic alteration followed by late propylitic and phyllic alterations. A variety of mineralization styles are disseminated sulfides, veinlets, and stockworks veins.

Hydrothermal alteration and mineralization can be divided into four stages, Stage I quartz+magnetite±chalcopyrite±pyrite±molybdenite veins associated with potassic alteration, Stage II quartz+molybdenite±chalcopyrite±pyrite veins associated with potassic and phyllic alteration, Stage III quartz+pyrite±chalcopyrite±sphalerite

±galena veins associated with phyllic alteration, Stage IV quartz±calcite±anhydrite

±gypsum±pyrite veinlet with weak propylitic alteration. Chalcopyrite mineralization mainly occurred as stockwork veinlets, ore-bearing quartz veins and dissemination in host rocks while molybdenite mainly occurs in quartz veins and at the margin of quartz veins. Copper and molybdenum mineralization was accompanied with both potassic and phyllic alterations.

Chapter 5 presents the fluid inclusion study and sulfur isotope analysis on quartz veins in different stages. Six types of fluid inclusions are typically observed at

Halo: vapor-mono-phase (type I), two-phase liquid+vapor, liquid-rich (type II), two- phase vapor+liquid, vapor-rich (type III), three-phase liquid+vapour+anhydrite (type

VI), three-phase liquid+vapor+opaque (type V) and multi-phase halite-bearing inclusions consisting of liquid+vapor+halite±anhydrite±hematite+opaque minerals

(type VI). Fluid inclusions in quartz+magnetite+chalcopyrite+pyrite vein (Stage I vein) and quartz vein (Stage IV vein) associated with potassic alteration and silicic alteration consist of four types of fluid inclusions (II, III, V, and VI) and six types of fluid inclusions (I-VI), respectively. The liquid-vapor homogenization temperatures

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(Th) of type VI fluid inclusions in Stage I vein and unknown stage associated potassic and silicic alteration, respectively, are lower than the halite dissolution temperatures

(Td), suggesting existence of NaCl saturated at the time of entrapment of the type VI fluid inclusions. Wide ranges of Th and Td of halite-bearing inclusions ranging from

280 to 460oC and 425 to 485oC of in Stage I vein, respectively, and 182 to 320oC, and

256 to >500oC in Stage IV vein, respectively, suggest heterogeneous entrapment of gaseous vapor and hypersaline brine. The minimum pressures and temperatures were estimated to be around 43 bars and 280oC and 10 bars and 182oC for potassic alteration and silicic alteration, respectively. Fluid inclusions in quartz+ molybdenite vein (Stage

II vein), quartz+pyrite+chalcopyrite+sphalerite+galena vein (Stage III vein), quartz+ pyrite+chalcopyrite+sphalerite+galena vein (Stage III vein) and quartz+pyrite vein

(Stage III vein) associated with phyllic alteration are composed of liquid-rich type two- phase inclusions, and they homogenize into a liquid phase at temperatures ranging widely from 174 to 264oC, 174 to 306oC, 201 to 357oC and 201 to 358oC, respectively, suggesting boiling with salinity from 4.0 to 14.0 wt. %, 0.3 to 2.0 wt. %, 0.5 to 14.0 wt. %, 1.5 to 14.0 wt. % NaCl equivalent, respectively. Pressures about 13 bars, 20 bars, 20 bars, and 13 bars were estimated for aqueous solution at 174oC, 174oC, 201oC,

201oC, respectively. Sulfur isotopic composition of ore sulfides are homogeneous

(δ34S = about +3 ‰) throughout the mineralization stages. These values are close to zero, which suggests a deep-seated, most likely a magmatic source.

Chapter 6 gives general conclusion and recommendations for further research on the Halo porphyry copper-molybdenite prospect. According to the results mention above, the Halo prospect is a porphyry copper-molybdenum prospect which was formed in a subduction-related tectonic setting, likely a volcanic arc. Drill holes HD1

iv and HD2 are situated close to the center of porphyry deposit than drill holes HD3 and

HD4. Detailed study on diamond drill cores should be carried out to interpret the subsurface alteration and mineralization that would define economic potential as well as to develop the accurate model of the mineralization area.

Acknowledgements

This research would not have been successful without help, guidance, and support from many people during my study at Kyushu University, Japan. Therefore, I would like to take this opportunity to express my gratitude towards them. I wish to express my sincere thanks to Professor Koichiro Watanabe, Department of Earth Resources Engineering, Kyushu University in Japan for his kind support and encouragement to carry out this research work, advice and reading the manuscript and give facilities in varies ways. I wish to express my special thanks to Associate Professor Tetsuya Nakanishi, Kyushu University Museum, Kyushu University, Japan for his acceptance, of being my advisor. Without his acceptance, I might have no chance to continue my study in this laboratory. Many thanks for his supervision, guidance, valuable advices, essential idea and suggestions during field work and writing dissertation. His explanation is very important for me and it can make me know more how to select good samples and organize my samples. I would like to express my deepest grateful from my heart to Professor Akira Imai, Department of Earth Resources Engineering, Kyushu University in Japan for his valuable time to review draft of my dissertation and contributing the essential ideas, constructive suggestions, helpful comment and criticism in order to improve the quality of this dissertation. This dissertation would never successfully complete without his supervision, kind support and good advices. He make me have conformable feeling during I discuss with him.

I wish to express my special thanks to Associate Professor Kotaro Yonezu, Department of Earth Resources Engineering, Kyushu University in Japan for his kindness, caring, supporting, encouragement and guidance me a lot during my study in Japan. I am thankful to him for his guidance, essential idea and suggestion during field work and value time to read my dissertation. Associate Professor Yonezu always provide me the opportunities to join many conference and field trips, it made me have a chance to learn and improve my knowledge related to my study.

I wish to express my special thanks to Assistant Professor Thomas Tindell, Department of Earth Resources Engineering, Kyushu University in Japan for his kind

vi help, advice, suggestions, encouragement, editing the manuscript and dissertation critically and guidance me how get the good samples during field work and how to prepare sulfur isotope. He also provide me the good document related to my research, it is very useful and make me can understand more about my research.

I am also grateful to my thesis examiner professor Kazuya Idemitsu for his comments and suggestions during my final defense.

I am deeply acknowledged to the ASEAN University Network/Southeast Asia Engineering Education Development Network (AUN/SEED-NET), Japanese International Cooperation Agency (JICA) for the PhD scholarship and financial support. We would like to special thank JSPS KAKENHI Grants Number 18H01927 and JSPS Core-to-Core Program provide us financial support during field work.

I am also indebted to all lecturers and Dr. Nallis Kry, a head of the Faculty of Geo-resources and Geotechnical Engineering, Institute of Technology of Cambodia, Cambodia, who has given me the constant support and guidance for my PhD at Kyushu University. A special appreciation also goes to Dr. Chea Samneang who encourage me to continue my study in Kyushu University. Honestly, without his encouragement, I might not continue Ph.D.

I am greatly thankful to Dr. Bun Kimngun and Ms. Sio Sreymean, lecturer of Geo-resources and Geotechnical Engineering, Institute of Technology of Cambodia, for providing much help in field-work.

I am deepest grateful to Mr. Jocelyn Pelletier, a Master of Science in Geology- Geoscienc, Geocoop, Montreal, Quebec, Canada for his suggestions, encouragements and advices and kindness to provide many documents and explain me the basically related to porphyry copper system. He always spends his time to explain me when I need him.

I would like to express my deepest thanks to Mr. John Dau Pau, a Vice President of Operation, Mr. Mike Weeks, a chairman in Angkor Gold, for allowing and supporting to the field research in the Halo prospect, Oyadao South area, Ratanakiri, Cambodia. I would like to thanks also for Craig T. Richardson for is excellent master thesis study made on Phum Syarung-Dok Yong Fault Corridor (Cambodia), and the

vii exceptional cooperation of Dennis Ouellet (Exploration Manager of Angkor Gold Corp.).

I am greatly thankful to the lab secretary, Ms. Mami Mampuku for her support, assistance, her speedy working to process any of my related documents. It is really joyful and fun to work with her. I also thank all the members and staffs of Economic Geology Laboratory, Kyushu University for their very great and comfortable greeting during my research study and their useful suggestions for me for all circumstances. It is really exciting and uncomfortable memories for me to work with them during laboratory works.

Last but not least, my sincere thanks and appreciation go to my beloved parents, sister and brothers who have been cut off from my love and care during this study. This study would never have been completed without their warm love, support, advices, encouragement and sacrifice. Their loves is big power for me to fight with all problems. I desire to share everything I have with you because I do love you.

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Contents

Abstracts ...... i

Acknowledgements ...... vi

Contents...... ix

List of Figures ...... xii

List of Tables ...... xxiii

Chapter 1: Introduction ...... 1

1.1 Background ...... 1

1.2. Location and accessibilities ...... 5

1.3 Statement of the Problem and Objectives ...... 6

1.4 Methodology ...... 7

1.4.1 Field work methods ...... 7

1.4.2 Laboratory work methods ...... 8

1.5 What is the porphyry deposit ...... 10

1.5.1 Overview on porphyry copper deposit ...... 10

1.5.2. Alteration-mineralization zoning in porphyry Cu deposits ...... 13

1.5.3 Porphyry Cu veinlet relationships ...... 15

1.5 Thesis Organization ...... 18

Chapter 2: Regional Geological Setting and Samples ...... 24 2.1. Introduction ...... 24

2.2. Regional Tectonic Setting and Ore Deposits of Dalat-Kratie Belt (DKB) ..... 24

2.3 Distribution of Granitic Rocks in South China and Indochina Terrane ...... 27

2.3.1 Distribution of Granitic Rocks in Cambodia and Dalat-Kratie Belt ...... 27

2.3.2 Distribution of Granitic Rocks in South China ...... 30

2.4 Geological Structure of Cambodia ...... 32

2.5 The Halo Porphyry Copper-Molybdenum Deposit ...... 34

2.6 Lithology in the Halo Prospect ...... 38

2.6.1 Outcrop Samples ...... 39

2.6.2 Drill Core Samples ...... 40

2.7 Conclusions ...... 46

Chapter 3: Lithogeochemistry of Igneous Rocks in the Halo Prospect ...... 51

3.1 Introduction ...... 51

3.2 Whole-rock Major and Trace Elements Geochemistry ...... 51

3.3 REE Geochemistry of intrusive rocks ...... 65

3.4 Molar Element Ratios ...... 69

3.5 Discussion ...... 71

3.5.1 Genetic implication ...... 71

3.5.2 Tectonic Affinity and Petrogenesis ...... 73

3.5.3 Alteration Lithogeochemistry ...... 76

3.6 Conclusions ...... 78

Chapter 4: Hydrothermal Alteration and Mineralization of the Halo Prospect 83 4.1 Introduction ...... 83

4.2 Wall Rock Alteration ...... 83

4.2.1 Surface ...... 83

4.2.2 Drill hole HD1 ...... 86

4.2.3 Drill hole HD2 ...... 90

4.2.4 Drill hole HD3 ...... 92

4.2.5 Drill hole HD4 ...... 93

4.3 Mineralization and Vein System Mineralogy ...... 97

4.4 Discussion and Conclusions ...... 108

Chapter 5: Fluid Inclusion Microthermometry and Sulfur Isotopes...... 110

5.1 Introduction ...... 110

5.2 Fluid Inclusion Petrography ...... 110

5.3 Microthermometry ...... 114

5.3.1 Stage I Vein ...... 114

5.3.2 Stage II Vein ...... 115

5.3.3 Stage III Vein ...... 115

5.3.4 Stage VI Vein ...... 117

5.4 Sulfur Isotopes Analysis ...... 121

5.5 Discussion ...... 123

5.6 Summary and Conclusions ...... 129

Chapter 6: General Conclusions and Discussion ...... 133 6.1. Comparison of porphyry copper deposit worldwide ...... 133

6.1.1 Magmatism and Ore-bearing Intrusions at the Halo ...... 133

6.2 Formation of the Halo porphyry copper-molybdenum prospect...... 137

6.3 General conclusion ...... 141

6.4 Recommendation for further research ...... 142

References ...... 143

Appendix ...... 147

List of Figures

Figure 1. 1 Mineral deposits of Indochina Terrane including Cambodia, Vietnam, Thailand and Laos (modified after Khin Zaw et al., 2010)...... 4

Figure 1. 2 Location of the Halo porphyry copper-molybdenum prospect other prospects in Ratanakiri (Modified after Angkor Gold Corp., 2018a). . 5

Figure 1. 3 Worldwide distribution of porphyry Cu deposits. Note, most of the porphyry deposits are distributed along convergent margins. Porphyry Mo deposits are not shown. Modified after Sun et al. (2013b). Data sources: Mutschler et al. (2010)...... 10

Figure 1. 4 Two different models for porphyry Cu ±Au ±Mo deposits. (A) Porphyry deposits are formed in normal arc rocks (after Richards, 201 a). According to this model, even the formation of giant porphyry deposits is nothing special but optimization of normal ore-forming processes, controlled by distinct tectonic configurations, reactive host rocks, or focused fluid flow that have helped to enhance the overall process (Richards, 2013). (B) Porphyry deposits are associated with slab melts (modified after Wilkinson, 2013), which have high initial Cu contents (Sun et al., 2011)...... 12

Figure 1. 5 Schematic of the typical hydrothermal alteration pattern encountered in porphyry-type ore deposits. These deposits have large alteration footprints; however, the distribution of each type may vary significantly in extent and form from deposit to deposit (Sillitoe, 2010)...... 14

Figure 1. 6 Schematic chronology of typical veinlet sequences in (a) porphyry Cu- Mo deposits and (b) porphyry Cu-Au de-posits associated with calc- alkaline intrusions Porphyry Cu-Au deposits hosted by alkaline intrusions are typically veinlet poor (Barr et al., 1976; Lang et al., 1995; Sillitoe, 2000, 2002). Background alteration between veinlets is mainly potassic, which is likely to contain more K-feldspar in the Mo-rich than the Au-rich porphyry Cu stockworks. Note the common absence of B- and D-type veinlets from Au-rich porphyry Cu stockworks and M-, magnetite-bearing A-, and chlorite-rich vein-lets from Mo-rich porphyry Cu stockworks. Veinlet nomenclature follows Gustafson and

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Hunt 1975; A, B, and D types) and Arancibia and Clark (1996; M type)...... 16

Figure 2. 1 Mineral deposits of Indochina Terrane including Cambodia, Vietnam, Thailand and Laos (modified after KhinZaw et al., 2010)...... 26

Figure 2. 2 Geologic map of Cambodia (United Nations, 1993) showing location of granites and their magnetic susceptibility (x10-3SI unit) (Sitha et al., 2012). Note: age of Baseth and Phnom Den (Sitha et al., 2012) and other from (Indochina Mining Limited, 2010; Richardson et al., 2016) ..... 28

Figure 2. 3 Simplified geological map of the Dalat zone shows the distribution of granitoid rocks of the Dinhquan, Cana and Deoca suites (Tien et al., 1991). Letters and number be-side solid squares denote sam-ple numbers. The upper inset shows that from mid Jurassic through mid- Cretaceous times the SE Asian margin was an Andean-type arc (Taylor and Hayes 1983). NW-direction subduction beneath the continent is evidenced by wide-spread rhyolitic volcanism and granitic intrusions along SE China (e.g. Jahn et al. 1976) and SE Vietnam. The lower inset shows Vietnam and location of study area...... 29

Figure 2. 4 Simpliﬁed geological map of south China showing the distribution of Mesozoic granitoid and volcanic rocks (modiﬁed after Yu et al., 2010; Zhou et al., 2006)...... 30

Figure 2. 5 Simplified geological map and principle features of the geological structure of Cambodia (United Nations, 1993)...... 33

Figure 2. 6 Lithological map in the Halo prospect with samples location. UTM 48N WGS84, (Richardson et al., 2016) ...... 36

Figure 2. 7 (a) Alteration map from filed observation and SWIR interpretation in the Halo prospect (Richardson et al., 2016), (b) Core logs of four drill cores studies here (from left to right HD1, HD2, HD3 and HD4) showing the approximate position of samples...... 38

Figure 2. 8 Photographs (A-C) and photomicrographs (a-c) of selected igneous rocks; (A) and (a) diorite at surface; (B) and (b) granodiorite at surface; (C) and (c) andesite at surface. Abbreviation: pl: plagioclase, Ksp: K-

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feldspar, hbl: hornblende, bt: biotite, qtz: quartz, ser: sericite, and py: pyrite...... 40

Figure 2. 9 Photographs (A-C) and photomicrographs (a-c) of selected igneous rocks (A) and (a): dacite in HD1 ; (B) and (b): quartz feldspar porphyry in HD1; (C) and (c): andesite porphyry in HD1; Abbreviation: pl: plagioclase, Ksp: K-feldspar, hbl: hornblende, bt: biotite, qtz: quartz, ser: sericite, s.bt: secondary biotite, py: pyrite and mag: magnetite. . 42

Figure 2. 10 Photographs (A-C) and photomicrographs (a-c) of granodiorite porphyry in HD-2. Abbreviation: pl: plagioclase, Ksp: K-feldspar bt: biotite, qtz: quartz, ser: sericite, s.bt: secondary biotite, epi: epidote, py: pyrite and mag: magnetite...... 43

Figure 2. 11 (A) and (a): granodiorite in HD3; (H), (h), (I) and (i): hornblende diorite in HD4. Abbreviation: pl: plagioclase, Ksp: K-feldspar, hbl: hornblende, bt: biotite, qtz: quartz, ser: sericite, s.bt: secondary biotite, epi: epidote, py: pyrite and mag: magnetite...... 45

Figure 3. 1 (a) Alteration box plot with the alteration index (AI) versus the chlorite- carbonate-pyrite index (CCPI) (Large et al., 2001); (b) TAS diagram for plutonic rocks using total alkalis versus silica of (Cox et al., 1979);

Al2O3/(K2O+Na2O)] diagram (Chappell and White, 1974; Maniar and Piccoli, 1989). Abbreviation: DIO: diorite on the surface; GRDO: granodorite on surface; QFP1: quartz feldspar porphyry in drill hole HD1, GRDP2: granodiorite porphyry in HD2; DI3 and GRD3: diorite and granodiorite, respectively, in HD3, HDI4 and HGRD4: hornblende diorite and hornblende granodiorite, respectively, in drill hole HD4. 59

Figure 3. 2 (a) Zr/TiO2versus Nb/Y diagram derived for volcanic rocks of

(Winchester and Floyd, 1976, 1977), (b) SiO2 versus K2O (wt. %)

diagram of (Peccerillo and Taylor, 1976), (c) FeOt/MgO versus SiO2 diagram (Miyashiro, 1974). Abbreviation: DC1and ANP1: dacite and andesite porphyry, respectively, in drill hole HD1 and other symbols are the same as in Figure 3.1...... 61

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Figure 3. 3 Bivariate plots of SiO2 versus selected major elements. (a) SiO2

vs TiO2, (b). SiO2 vs FeO, (c) SiO2 vs Al2O3, (d). SiO2 vs MnO, (e)

SiO2 vs MgO, (f) SiO2 vs CaO, (g) SiO2 vs Na2O (h) SiO2 vs P2O5 of the different lithological units from the Halo prospect. Abbreviation: DIO-1 to DIO-3 and GRDO-1 to GRDO-3: diorite and granodiorite, respectively, exposed on surface; DC1-1 to DC1-4, ANP1-1 to ANP1-3, and QFP1-1 to QFP1-10: dacite, andesite porphyry and quartz feldspar porphyry, respectively, in drill hole HD1; GRD2-1 to GRD2-8: granodiorite porphyry in drill hole HD2; DI3-1 to DI3-2 and GRD3-1 to GRD3-2: diorite and granodiorite, respectively, in drill hole HD3; HDI4-1 to HDI4-5 and HGRD4-1 to HGRD4-2: hornblende diorite and hornblende granodiorite, respectively, in drill hole HD4. Locations are shown in Figures 2.3 and 2.4 ...... 62

Figure 3. 4 Bivariate plots of SiO2 versus minor elements, (a) SiO2 vs Zr, (b) SiO2

vs Rb (c) SiO2 vs Sr, (d) SiO2 vs Ba, (e) SiO2 vs Sc, (f) SiO2 vs V, (g)

SiO2 vs Cu, (h) SiO2 vs Mo, (i) NaO2+KO2 vs SiO2, (j) TiO2 vs V and

(k) Zr/TiO2 vs SiO2 . Symbols are same as Figure 3.3...... 65

Figure 3. 5 Chondrite-normalized rare earth element and primitive-mantle- normalized trace element patterns of intrusive and volcanic rocks in the Halo prospect (Sun and McDonough, 1989). Symbols and abbreviations are the same as Figure 3.3 ...... 68

Figure 3. 6 PER diagram of Pr versus Nd of the least altered and altered samples in the Halo prospect showing the linear plot that indicated the samples are cogenetic; (b) PER diagram of (2Ca+Na+K)/Nd versus Al/Nd to discriminates unaltered felsic samples from altered samples. All elements are expressed as molar concentrations except for Nd which is expressed in ppm. Symbols and abbreviations are the same as Figure 3.3...... 70

Figure 3. 8 Discrimination diagram for the origin of intrusive rocks in the Halo prospect and (a) plot Y (ppm) versus Sr/Y diagram with fields from (Defant and Drummond, 1990), (b) plot of La/YbN versus YbN with fields from (Martin, 1986) ; (c) (La/Yb)N versus MgO diagram, average crustal thickness, on the basic of (La/Yb)N ratio is from (Ahmadian et al., 2009) (d) (A) Rb/Nd versus Rb diagram (after

Schiano et al., 2010); (f) (C) Plot of Al2O3+FeO+MgO+TiO2 versus

Al2O3/(FeO+MgO+TiO2) (after Patiño Douce, 1999 ). Symbols are the same as in Figure 3.1...... 75

Figure 3. 9 (a) PER diagrams showing the degree of alteration for felsic rocks. Samples with x=1 are considered as fresh while samples with x=0 are highly altered; (b) K/Al versus to alteration index (x-axis) to discriminate the alteration samples such as muscovite, K-feldspar, biotite, kaolin alteration minerals and chlorite with fresh rocks. Symbols and abbreviations are the same as Figure 3.2...... 78

Figure 4. 1 (A), (a) quartz vein cutting silicified rock associated with silicic alteration (35o/67oS, S9.3; (B), (b) quartz+pyrite vein in silicic alteration ; (C), (c) quartz+pyrite+chalcopyrite+goethite vein cutting granodiorite associated with phyllic alteration (85o/80oS, HAL17A); (D), (d) quartz+molybdenite+pyrite vein in silicic alteration (25o/90oS, S8-1)...... 84

Figure 4. 3 Photographs (A-C) and photomicrographs (a-c) of phyllic alteration in drill hole HD1; (a) quartz+pyrite+chalcopyrite vein stockworks in dacite are heavily overprinted by sericite (depth 24m); (b)

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quartz+pyrite+chalcopyrite vein cut quartz feldspar porphyry associated with phyllic alteration (depth 62m); (c) quartz+molybdenite+pyrite vein cute quartz feldspar porphyry associated with phyllic alteration (depth 74m); (d),(e),(f) sericite replaced plagioclase subordinated with groundmass of quartz, biotite altered to chlorite in phyllic alteration, (E) X-ray diffraction pattern of bulk rock and oriented samples (D1-62). Abbreviation: qtz: quartz, bt: biotite, py: pyrite, cpy: chalcopyrite, mo: molybdenite...... 86

Figure 4. 4 Potassic alteration in drill hole HD1; (a) quartz-K-feldspar veinlet cutting quartz feldspar porphyry showing potassic alteration (depth 95m); (b) quartz feldspar porphyry consisting of pervasive pink K- feldspar and patches fine-grained hydrothermal biotite (depth 111m), (c) magnetite stockworks and quartz vein with pink K-feldspar halos host in andesite porphyry (depth 126m); (d) quartz+magnetite +chalcopyrite+pyrite vein cutting andesite showing K-feldspar altered around mineralized quartz veins (depth 107m); (e) magnetite veinlets, magnetite stockworks and quartz vein with K-feldspar halo in potassic alteration (depth 106m); (f) potassic alteration of quartz feldspar porphyry consisting of pervasive pink K-feldspar and patches of fine- grained hydrothermal biotite associated with quartz+pyrite +chalcopyrite+magnetite vein (depth 120m). Abbreviation: qtz: quartz, K-fsp: K-feldspar, bt: biotite, py: pyrite, cpy: chalcopyrite, mag: magnetite, mo: molybdenite...... 88

Figure 4. 5 Photomicrograph showing potassic alteration in HD1; (a) K-feldspar in quartz vein and groundmass of K-feldspar with magnetite and quartz on the margin of vein; (b) hornblende euhedral crystal has been altered to secondary biotite subordinated with groundmass of plagioclase, K- feldspar and quartz; (c) secondary K-feldspar replace igneous plagioclase and secondary K-feldspar and quartz occur as groundmass; (d) K-feldspar and quartz occur as groundmass with dissemination of magnetite; (e),(f) hydrothermal biotite occur as patches with chalcopyrite and magnetite in potassic alteration; (g) secondary biotite completely replace plagioclase, secondary K-feldspar rims igneous plagioclase, fined grained of secondary biotite; (h) and (i) hydrothermal

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biotite occurs as aggregates of fine-grained flakes with quartz and magnetite. Abbreviation: qtz: quartz, pl: plagioclase, K-fsp: K-feldspar, bt: biotite, ser: sericite, zr: zircon, mag: magnetite, cpy: chalcopyrite...... 89

Figure 4. 6 Vein and veinlet associated with potassic alterations in hole HD2, (a) quartz+molybdenite vein cutting by later quartz+calcite vein consisting of pervasive pink K-feldspar and patches fine-grained hydrothermal biotite (depth 218m); (b) quartz+molybedenite vein cut granodiorite porphyry (depth 220); (c) potassic altered granodiorite porphyry with pink K-Feldspar and fine-grained patches hydrothermal biotite associated with quartz+chalcopyrite+pyrite+magnetite+molybdenite vein (248m) (d) quartz+pyrite+chalcopyrite+molybdenite vein cut by later pyrite veinlet associated potassic alteration of granodiorite porphyry consisting of pink groundmass K-feldspar and fine-grained patches biotite (273m); (e) quartz+pyrite+chalcopyrite cut granodiorite porphyry (294m); (f) magnetite veinlet cutting granodiorite porphyry (depth 380m). Abbreviation: qtz: quartz, cpy: chalcopyrite, py: pyrite, mag: magnetite, mo: molybdenite...... 90

Figure 4. 7 Photomicrographs showing characteristics of potassic alteration in drill hole HD2; (a),(b) secondary K-feldspar rims igneous plagioclase, epidote alteration of plagioclase, sericite replaced plagioclase (depth 220m); (c) groundmass K-feldspar halo on quartz vein, cluster of hydrothermal biotite, secondary K-feldspar rims igneous plagioclase (depth 220m); (d),(e),(f) find-grained secondary K-feldspar rims igneous plagioclase, cluster of hydrothermal biotite, anhydrite replaced by secondary biotite, sericite replaced plagioclase and interstitial quartz in the groundmass (depth 273m and 294m) ; (g),(h) hornblende is almost altered into secondary biotite, sericite replaced plagioclase (depth 312m, 327m); (j),(k) anhydrite replaced hydrothermal biotite, sericite replaced plagioclase (depth 380m). Abbreviation K-fsp: K- feldspar, pl: plagioclase, qtz: quartz, hbl: hornblende, bt: biotite, epi: epidote, ser: sericite, cal: calcite...... 91

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Figure 4. 8 (a) quartz+molybedenite vein cutting granodiorite associated with phyllic alteration (depth 87m); (b) quartz+magnetite+chalcopyrite +pyrite vein cutting diorite associated with propylitic alteration (depth 261m); (c) quartz+molybdenite vein cut by calcite veinlet host in diorite associated with prophylitic alteration (depth 284m); photomicrograph showing phyllic alteration and propylytic alteration: (d), (e) quartz, sericite, chlorite and pyrite in phyllic alteration; (f) epidote alteration of plagioclase and chlorite in prophylitic alteration. Abbreviation: qtz: quartz, K-fsp: K-feldspar, pl: plagioclase, bt: biotite, chl: chlorite, ser: sericite, epi: epidote, py: pyrite, cpy: chalcopyrite, mo: molybedenite, mag: magnetite...... 92

Figure 4. 9 Propylititc and phyllic alteration in drill hole HD4 (a) calcite+epidote veinlets and epidote alteration in hornblende diorite (depth 224m); b) pyrite veinlet with epidote alteration halo in hornblende diorite (depth 262m); (c) quartz+anhydrite+pyrite vein cut hornblende diorite (depth 277m); (d) quartz+anhydrite+pyrite cut hornblende diorite associated with phyllic alteration (depth 289m). Abbreviation: qtz: quartz, epi: epidote, anh: anhydrite, py: pyrite...... 93

Figure 4. 10 Photomicrographs showing characteristics of propylytic and phyllic alteration in hole HAL17-004D (a),(b),(c) epidote alteration of plagioclase, sericite replaced plagioclase, anhedral quartz and calcite veinlet (D4-224, depth 224m); (d) epidote alteration of plagioclase, sericite replaced plagioclase (D4-262, depth 262m); (e) and (f) epidote alteration of plagioclase, chlorite, quartz, weakly sericite (D4-277, depth 277m); (g), (h) and (i) sericite replaced plagioclase, biotite altered to chlorite, hornblende, quartz and fine-grained pyrite (D4-289, depth 289m). Abbreviation: qtz: quartz, pl: plagioclase, bt: biotite, chl: chlorite, ser: sericite, epi: epidote, cal: calcite, py: pyrite...... 94

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chalcopyrite and pyrite in quartz+magnetite+pyrite+chalcopyrite associated with potassic alteration (D1-95); (e) and (f) chalcopyrite, magnetite, hematite and covellite disseminated throughout the rocks and veinlet are hostedin andesite dyke (D1-126) ; (g) and (h) blade- scaly molybdenite occurs as veinlet associated with phyllic alteration (D2-364 and S8.1); i) chalcopyrite inclusion in pyrite and pyrrhotite associated with phyllic alteration (HL06, outcrop sample). Abbreviations: cpy: chalcopyrite, py: pyrite, ga: galena, mag: magnetie, hm: hematite, mo: molybdenite, po: pyrrhotite and cv: covellite, D1: drill hole HD1, D2: drill hole HD2, S8.1 and HL06: outcrop sample...... 98

Figure 4. 12 Photomicrographs of ore mineralization in each vein stages: (a), (b), (c) magnetite (mag) and chalcopyrite (cpy), pyrite (py), hematite (hm) and covellite (cv) in stage I vein associated with potassic alteration;(d) molybdenite (mo) occur as veinlets in stage II associated with phyllic alteration; (e) pyrite, chalcopyrite, shpalerite (sp) and galena (ga) in stage III associated with phyllic alteration; (f) pyrite veinlets in stage IV associated with propylitic alteration...... 102

Figure 4. 13 (a), (b), (c) Stage I vein associated with potassic alteration d) Stage II vein associated with phyllic alteration; (e) Stage II and III vein associated with phyllic alteration; (f) Stage III quartz+molybdenite +pyrite+chalcopyrite vein cut by Stage IV gypsum veinlet; (g) Stage IV anhydrite+pyrite+chalcopyrite cutting diorite, with epidote and chlorite alteration halo; qtz: quartz, mag: magnetite, cpy:chalcopyrite, py: pyrite, mo: molybdenite, sp: sphalerite, ga: galena, anh: anhydrite, gym: gypsum...... 103

Figure 4. 14 (a) Cu-Mo concentration in ppm associated with phyllic alteration and silicic alteration hosted in diorite, granodiorite and silicified rock, (b) lithology and alteration zone in drill hole HAL17-001D (0-140m) with concentration of Cu-Mo (ppm), (c) Cu-Mo concentration in ppm associated phyllic alteration and potassic alteration in drill hole HD2. Abbreviation: Lith.-lithology, Alt.-alteration, Cu-copper, Mo- molybdenum...... 105

Figure 5. 1 Photomicrographs of various types of fluid inclusions (a), (b), (c), (d) Type I mono phase vapor-rich inclusion (Type I) coexist with two phase vapor-rich inclusion (Type III), Type II inclusion with liquid and a vapor bubble in quartz vein (unknown stage) associated with silicic and quartz+molybdenite vein (Stage II Vein) associated with phyllic alteration; (e), (f), (g) Type III inclusion vapor-rich inclusion coexist with liquid-rich inclusion, Type V inclusion anhydrite-bearing fluid inclusions in quartz vein (unknown stage) associated with silicic alteration; (h) and (i) Type V inclusion with liquid, a vapor bubble and opaque mineral in quartz vein (unknown stage) associated with silicic and quartz+molybdenite vein (Stage II Vein) associated with phyllic alteration; (j), (k),(l) Type VI inclusion with liquid, a vapor bubble, halite and opaque mineral in quartz vein (Stage I and unknown stage) associated with silicic and potassic alteration. Abbreviation L: liquid, V: vapor, H: halite, hm: op: opaque mineral and anh: anhydrite ..... 112

Figure 5. 2 Histograms of homogenization temperatures and salinity of fluid inclusions in different stage of quartz associated with different alteration: (a), (b) fluid inclusions in quartz+magnetite+pyrite +chalcopyrite vein (Stage I Vein) associated with potassic alteration (D1-120, depth 120m); (c), (d) fluid inclusion in quartz+molybdenite vein (Stage II) associated with phyllic alteration (S8.1, outcrop sample); (e), (f) fluid inclusion in quartz+pyrite+chalcopyrite+sphalerite +galena (Stage III) associated with phyllic alteration (S9.1,outcrop sample); (g), (h) fluid inclusions in quartz+pyrite+chalcopyrite galena+sphalerite vein (Stage III Vein) associated with phyllic alteration (D1-53, depth 53m) ; i and j) fluid inclusion quartz+ pyrite+chalcopyrite vein (Stage III vein) associated with phyllic alteration (HAL17A, outcrop sample); k and l) quartz vein (Stage IV Vein) associated with silicic alteration (S9.3, outcrop sample)...... 120

Figure 5. 3 Histogram of sulfur isotope compositions of sulfides and sulfate from the Halo Mo-Cu deposit. Abbreviation: py: pyrite, cpy: chalcopyrite, mo: molybdeneite ...... 121

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Figure 5. 5 Comparison of the Halo porphyry copper-molybdenum deposit with other porphyry copper-molybdenum deposits (Field et al., 2005; Imai, 2005, Meng et al., 2006; Zheng et al., 2017) and porphyry copper deposit from several deposit (Field and Gustafson, 1976, Ohmoto and Rye, 1979; Ohmoto and Goldhaber, 1997; Rye, 2005; Wilson et al., 2007). Abbreviation: Cu: chalcopyrite, Mo: molybdenite...... 129

Figure 6 1 Porphyry copper deposits in the context of plate tectonics (Groves et al., 2005)...... 133

Figure 6 2 Schematic tectonic evolution of Halo prospect in Dalat-Kratie Belt, Between Late Jurassic and Early Cretaceous (modified after Ding et al., 2017; Qing et al., 2018 ), Thuy et al. (2002), Thuy et al. (2004), and Manaka et al. (2012) were used as references. Abbreviation: DKB: Dalat-Kratite Belt, SWC: Southeast Cambodia including Halo prospect...... 136

Figure 6. 3 Genetic model for formation of Halo porphyry copper-molybdenum prospect. Sillitoe (2010) was used as reference. This Model: Not to Scale ...... 139

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List of Tables

Table 1. 1 Major Mines, deposits and prospects of Indochina Terrane ...... 3 Table 1. 2 Definitions of alteration and mineralization terminology used in this study; based on Titley (1982) and Gifkins et al. (2005)...... 17 Table 2. 1 Summary of petrographic characteristics of intrusive rocks in the Halo prospect ...... 46 Table 3. 1 Concentrations of major elements oxides (wt. %), trace (ppm) and rare earth elements (ppm) of intrusive and volcanic rocks in the Halo prospect ...... 52 Table 4. 1 Alteration mineral assemblages (petrography and XRD analysis) and type of alteration in the Halo prospect at surface...... 94 Table 4. 2 Alteration mineral assemblages (petrography and XRD analysis) and type of alteration in drill holes of Halo prospect...... 95 Table 4. 3 Mineral paragenesis for the Halo porphyry copper-molybdenum prospect ...... 99 Table 4. 4 Mineralization related to alteration ...... 101 Table 4. 5 summary of ore minerals assemblage and alteration in drill hole .... 106 Table 4. 6 Summary of ore minerals assemblage and alteration in drill hole ... 107 Table 5. 1 Summary of fluid inclusion petrography ...... 113 Table 5. 2 Sulfur isotope compositions (δ34S‰) of sulfides from the Halo Porphyry Mo-Cu deposit ...... 122 Table 5. 3 Summary of fluid inclusion microthermometry of the Halo deposit...... 126 Table 6. 1 Summary on rocks, mineralization, and alteration, copper and molybdenum concentration in each drill holes (HD1 to HD4) ...... 140

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Chapter 2

Chapter 1: Introduction

1.1 Background

Cambodia is one of countries of Southeast Asia situated in the Indochina peninsula which shares borders with Thailand in the west and northwest , Laos in the northeast, Vietnam in the southeast and the Gulf of Thailand in the southwest.

Presently, Indochina hosts a number of mineral deposits including epithermal and sediment-hosted ore deposit, porphyry and porphyry-related skarn deposits (Metcalfe,

2013). There are significant resources of gold, silver, and copper in Indochina for future discovery opportunities; especially under-explored districts such as Cambodia.

The Halo porphyry copper-molybdenum deposit is located in Oyadao South, Province of Ratanakiri, and northeastern Cambodia within Dalat-Kratie Belt (DKB) of southeastern portion of Indochina Terrane, 450 km northeast of the national capital city of Phnom Penh (Figure 1.1). The DKB is one of meltallogenic belts of Indochina

Terrane, which occupies the region from Cambodia to southern Vietnam. Granitic rocks intruded the southern continuations of the Truong Son and Loei Fold Belts

(Figure 1.1) (Khin Zaw et al., 2010).

In recent years, there many foreign companies do exploration in Cambodia such as Angkor Gold Corp, Renaissance Minerals (Cambodia) Limited, GeoPacific

Resources Limited etc. They are engaged in exploration and development of porphyry copper-molybdenum Porphyry, epithermal gold vein targets, and skarn potential; gold deposit; and gold-silver deposit in Ratanakiri province of Northeastern Cambodia,

Chapter 2

Mondulkiri province of Eastern Cambodia, and Preah Vihear of Northern Cambodia, respectively. Ratanakiri province is potential region to produce more porphyry and porphyry related to mineral deposit especially in Oyadao district. The Oyadao South

License is approximately 247 km2, was renewed in 2017 for 3 years with extensions for additional 4 years. The Oyadao South License contains several prospects including the Halo Prospect. The Oyadao South License has been explored by Angkor Gold Corp which cooperated with Janpan Oil, Gas and Metals National Corporation (JOGMEC)

(Angkor Gold Corp., 2015). The Halo porphyry copper-molybdenum prospect is a porphyry system in Oyadao district, northeastern part of Cambodia. The district has a potential for porphyry-type deposits such as porphyry copper-molybdenum (Halo prospect, China Wall prospect) and porphyry copper-molybdenum-gold (Okalla prospect). Moreover, this prospect is surrounded by producing mines such as Sepon,

Phu Kham (skarn in Laos), Phouc Son, Bong Mieu (sediment-hosted gold, orogenic gold, skarn copper-gold in Vietnam), Chatree (low-sulfidation epithermal gold-silver in Thailand), Phum Syrung gold mine (porphyry related to polymetallic vein deposit, north of the Halo prospect, Cambodia), (Table 1.1). This prospect is located on the edge of a monzogranite pluton to the south. The host rocks of this prospect are composed of felsic and intermediate volcanic rocks which are covered by prominent silica cap outcrops on hilltops in the area. The volcanic rocks were intruded by diorite, granodiorite, and a quartz feldspar porphyry stock. These multiple intrusions brought molybdenite and copper mineralization in veins and veinlets which are found in both the intrusive and volcanic units (Angkor Gold Corp, 2015).

Chapter 2

Table 1. 1 Major Mines, deposits and prospects of Indochina Terrane

Deposit/Prospect/Mine Deposit Types Deposit Age Resources Company /Country Besra Gold Bong Mieu (Mine) 2.3 Mt at 1.8 Orogenic Au Unknown Inc. Vietnam g/tAu

Phoc Son (Mine) Besra Gold Sediment 3.1 Mt at 6.7 Vietnam Unknown Inc. Hosted Au g/tAu

Permian– 4.75 Mt Au Sepon (Discovery Sedimentary Carboniferous for 83 Mt at MMG Ltd. Main-Mine), Laos rock -hosted Au 1.8 g/tAu 240 Mt at Porphyry- Pan Aust Phu Kham (Mine), Carboniferous– 0.55%Cu, related-skarn Company Laos Early Permian 0.24 g/t Au & Cu-Au 2.2 g /t Ag Kingsgate Chatree Epithermal Au– 3.10 Mt Au, Triassic Consolidated (Min), Thailand Ag 24.14 Mt Ag Limited Okvau (Deposit), Intrusion related 15.8Mt at Renaissance Cambodia Cretaceous Au 2.22g/t Au Minerals Ltd.

Angkor Gold Porphyry related Corp and Phum Syrung Mine 5.6 Mt at to polymetallic Triassic Mesco Gold Cambodia 3.5g/t Au vein deposit Cambodia Co., Ltd. Okalla East (Prospect) Cu-Mo-Au Angkor Gold Cretaceous N.A Cambodia Porphyry Corp. China Wall (Prospect) Cu-Mo Angkor Gold Cretaceous N.A Cambodia Porphyry Corp. Halo (Prospect) Cu-Mo Angkor Gold Cretaceous N.A Cambodia Porphyry Corp.

Chapter 2

Figure 1. 1 Mineral deposits of Indochina Terrane including Cambodia, Vietnam, Thailand and Laos (modified after Khin Zaw et al., 2010).

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1.2. Location and accessibilities

The Halo porphyry copper-molybdenum prospect is located in northeastern

Cambodia, approximately 450km northeast of the capital city of Phnom Penh. The

Halo prospect is located in Oyadao South license, Oyadao district, Ratanakiri province,

Cambodia at coordinate approximately 756000E to 760000E and 1501000N to

1503000N (Figure 1.2). It can be accessed by car or motorcycle from Phnom Penh city to Oyadao district and from Oydao district to Halo prospect by car, motorcycle and walking depend on the condition of road.

Figure 1. 2 Location of the Halo porphyry copper-molybdenum prospect other prospects in Ratanakiri (Modified after Angkor Gold Corp., 2018a).

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1.3 Statement of the Problem and Objectives

Cambodia occupies the south-central region of the Indochina peninsula.

According to the topographic conditions, Cambodia is divided into four main regions (i) the coastal plain of southwest part, (ii) the southwestern highland, (iii) the Mekong low land of central part and (iv) the eastern plateau. After the civil war was terminated in 1993, the rapid development of the city, provincial and all the sectors are so significant. Cambodia’s economy is based on tourism, agriculture and industries.

But in the future, it will be based on the petroleum and mineral resources. The mineral resource is one of the large sectors with opportunities of continued economic development in stable potential in Cambodia. Now there are many foreign companies interested in investment and exploration in this sector, whereas the geological history is poorly known and lack of mineral deposit information. For example such as the Halo prospect, there are only one research carried out on the Halo porphyry copper molybdenum prospect, regarding geological mapping, termite mound geochemistry, short wave infrared (SWIR) spectroscopy alteration mapping and rock- chip geochemistry on surface (Richardson, 2016). There are four drill holes in the Halo prospect but there are no researcher has focused on four drill holes yet. There have not been studied in detail on intrusive rocks, hydrothermal alteration, ore mineralization, fluid inclusion study, geochemical characteristics of rocks and alteration lithogeochemistry in the Halo porphyry copper-molybdenum prospect.

Specifically, this study aims to:

1. Describe and discuss the lithology, characteristics of the intrusive rocks and

volcanic rocks to constrain the petrogenesis, tectonic setting.

Chapter 2

2. Identify lithogeochemistry of intrusive and volcanic rocks to demonstrate

elements transportation during hydrothermal alteration at the Halo prospect.

3. Categorize hydrothermal alteration (surface and subsurface) in the Halo

porphyry copper-molybdenum deposit

4. Characterize ore mineralization (surface and subsurface) in the deposit and its

relationship to alteration

5. Identify the origin of hydrothermal fluid responsible for alteration and

mineralization

6. Study sulfur isotope in order to understand about source of mineralized fluid at

the Halo porphyry copper-molybdenum prospect.

1.4 Methodology

In this study, two principal methods were applied including field investigation and laboratory-based studies.

1.4.1 Field work methods This PhD study included three field seasons in the Halo prospect, Oyadao district

(September, 2016, December, 2016, December, 2017). The field work was specifically focused on:

1. Outcrop samples and representative ore sample associated with quartz veins

were collected in Halo prospect.

2. Geological structures were examined in order to compare with previous work

from Angkor Gold Corp.

3. Detailed logging of selected diamond drill and rock chip holes at the drill hole

HD1, HD2, HD3 and HD4 in the Halo prospect.

Chapter 2

4. Collection of samples from outcrop and diamond drill holes for detailed

laboratory analyses.

During the field work, the author logged and sampled a total approximately

1600m of diamond drill cores from 4 drill holes at Halo prospect.

1.4.2 Laboratory work methods

In this study, 50 outcrop samples and 200 samples recovered from four drill holes in HAL17-001D, HAL17-002D, HAL17-003D and HAL17-004D composed of intrusive rocks, volcanic rock, altered rocks, rhyolite tuff, silicified rock and ores were collected during field investigation and core observation. Sixty petrographic thin sections and forty polished sections were prepared to identify, textural characteristics, alteration minerals and ore minerals of rocks and quartz vein-bearing mineralization and observed using a Nikon Eclipse E600 POL microscope equipped with an

AdvanCam-U3II camera. Both bulk and clay fraction X-ay diffraction analysis were conducted to identify mineral composition, alteration mineral assemblage using a

Rigaku Ultima IV X-ray diffractometer at Department of Earth Resources Engineering,

Kyushu University, Japan. A scanning electron microscope (SEM) using a

SUPERSCAN SS-550, equipped with energy disperse X-ray analyzer (EDAX) at the

Center of Advanced Instrumental Analysis, Kyushu University, was used to determine the chemical composition and confirmation ore mineral.

In order to understand petrogenesis and tectonic setting, and lithogeochemistry of intrusive and volcanic rocks, whole-rock major elements oxides, trace and rare earth elements concentrations of 60 samples including diorite, granodiorite, quartz feldspar porphyry, hornblende diorite collected from surface and four drill holes HD1, HD2,

Chapter 2

HD3 and HD4 were analyzed by X-ray fluorescence (XRF) spectroscopy using a

RIGAKU RIX-3100 and by inductively coupled mass spectrometry (ICP-MS) Alilent

Technologies 7500, respectively, at the Center of Advanced Instrumental Analysis,

Kyushu University. Loss on ignition (LOI) was determined by heating the samples at

1000oC for 2 hours to get relative weight loss.

Doubly polished sections of two quartz vein samples from different depths of

HAl17-001D and five quartz vein samples from outcrop samples were prepared for fluid inclusion study. Then, the microthermometric measurements were conducted using a Linkam LK600 cooling/ heating unit with a Nikon Y-IM microscope at the

Department of Earth Resources Engineering, Kyushu University. The homogenization temperatures and the final ice-melting temperatures were measured at the heating rate of 1°C min−1. The highest temperature of current working condition was placed at

550°C. The salinities of two-phase fluid inclusions are expressed as wt.% NaCl equivalent, which were estimated from the melting temperatures of the last crystal of ice (Bodnar, 1993) and salinities of multiple phase including halite, opaque minerals, reddish hematite were calculated using the halite dissolution temperature through equation reported by Sterner et al. (1988).

Sulfur isotope measurements were made on fifteen pyrite, three chalcopyrite, three molybdenite samples and three anhydrite samples. All sulfur isotope analysis was carried out the Scottish Universities Environmental Research Centre (SUERC) in

Glasgow, UK. Sulfur isotope composition of pyrite, chalcopyrite and molybdenite were analyzed by situ laser combustion from standard-polished block with calibration and correction report from Kelley and Fallick (1990), Kelley et al. (1992) and Wagner et al. (1992). Anhydrite was separated from anhydrite-pyrite vein and purified. Around

Chapter 2

5-10mg was utilized for isotopic analysis. Sulfur isotope composition of anhydrite was analyzed by convectional combustion procedures (Coleman and Moore, 1978;

Robinson and Kusakabe, 1975). The analytical precision, based on replicate measurements international standards NBS-123 (+17.1‰), IAEA-S-3 (−31.5‰), and the SUERC standard CP-1, (−31.5‰), with 1σ reproducibility around ± 0.2‰. Sulfur isotope compositions are given in δ34S notation as per mill (‰) variations from the

Vienna Canyon Diablo Troilite (V-CDT) standard.

1.5 What is the porphyry deposit

1.5.1 Overview on porphyry copper deposit

Porphyry deposits are hosts to one of the most important economic mineral associations (Cooke et al. , 2005; Halter et al., 2005; Heinrich et al., 2004; Mutschler et al., 2010; Sillitoe, 2010), accounting for ~ 80%Cu and ~ 95% Mo of the world's total reserves. It is also an important resource of Au, Ag, Zn, Sn and W. Most porphyry

Chapter 2

deposits are found above active subduction zones (Figure 1. 3) with a few occurrences at post-collisional or other tectonic settings (Sillitoe, 2010).

The consensus is that most of the porphyry Cu±Mo±Au systems are initiated by injection of oxidized adakitic magma saturated with aqueous fluids that are S- and metal-rich, i.e., the parental magmas must be water rich and oxidized (e.g., Ballard et al., 2002; Burnham and Ohmoto, 1980; Garrido et al., 2002; Imai, 2002; Liang et al.,

2006; Mungall, 2002; Sillitoe, 2010; Stern et al., 2007; Sun et al., 2013b). It is, however, still controversial as regards to: why high oxygen fugacity is favorable for the mineralization of porphyry deposits, how oxidized the magma could be, whether adakitic magma is essential for porphyry mineralization or whether the porphyry deposits can be associated with normal arc rocks (Figure 1. 4), and why the pure porphyry Mo deposits are also closely associated with highly oxidized magmas.

Chapter 2

Figure 1. 4 Two different models for porphyry Cu ± Au ± Mo deposits. (A) Porphyry deposits are formed in normal arc rocks (after Richards, 2010a). According to this model, even the formation of giant porphyry deposits is nothing special but optimization of normal ore-forming processes, controlled by distinct tectonic configurations, reactive host rocks, or focused fluid flow that have helped to enhance the overall process (Richards, 2013). (B) Porphyry deposits are associated with slab melts (modified after Wilkinson, 2013), which have high initial Cu contents (Sun et al., 2011).

Porphyry deposits form at depths of approximately 1–6 km below the paleosurface due to magmatic–hydrothermal phenomena associated with the emplacement of intermediate to felsic intrusive complexes (Seedorff et al., 2005).

Most porphyry deposits have a spatial, temporal, and genetic association with geodynamic processes at convergent plate margins where hydrous melts are generated in the sub arc mantle. These oxidized melts transport metals and volatiles to magma chambers located in the mid to upper crust, where fractional crystallization and volatile exsolution result in porphyry ore formation.

Chapter 2

Porphyry deposits can also be classified on the basis of the composition of magmatic rocks associated with mineralization. This scheme recognizes three subcategories of calc-alkaline porphyry deposits (low-K, medium-K, and high-K) and two subcategories of alkalic porphyry deposits (silica-saturated and silica-under saturated;

Lang et al., 1995). The alkalic porphyries are exclusively of Cu–Au character, whereas calc-alkaline deposits span the entire spectrum of Cu, Au, and Mo mineralization.

1.5.2. Alteration-mineralization zoning in porphyry Cu deposits

The emplacement of porphyry intrusions within the shallow crust drives large- scale hydrothermal circulation, producing large volumes of hydrothermally-altered rocks. These alteration patterns provide a useful vectoring tool for exploration in porphyry systems (Figure 1.5, Sillitoe 2010). Exsolved hydrothermal fluids form zoned alteration assemblages (Lowell and Guilbert 1970). The highest temperature and most proximal to the deeper magma chamber is the sodic-calcic alteration. This alteration forms at depths between 3.5 to >6 km and is generally devoid of sulphides

(Dilles and Einaudi 1992). Potassic alteration is characterised by K-silicates (K- feldspar and/or biotite) typically with accessory magnetite and anhydrite (Lowell and

Guilbert 1970, Sillitoe 2010). This alteration assemblage occurs within the core of the system dominated by magmatic fluids, typically brines (Ulrich et al. 2002). As these magmatic fluids move away from central up flow zones, the fluids cool and acidify

(i.e. activity of H+ increases). This acidification is reflected in the more distal alteration which is dominated by feldspar-destructive sericitic alteration (Giggenbach

1984) which can involve mixing with meteoric fluids (Reynolds and Beane, 1985) and/or just magmatic fluids (Harris and Golding, 2002). As the name suggests, this

Chapter 2

alteration is dominated by sericite (finely crystalline muscovite mica), quartz and pyrite. This alteration can be structurally controlled at shallower levels and dominates the roots of high-sulphidation epithermal deposits (Sillitoe 1999). The argillic and advanced argillic alteration zones, formed from highly acidic fluids, typically sit above the porphyry center (Figure 1.5) or, in telescoped deposits where exhumation during hydrothermal activity has superimposed later fluid flow events onto the core of the system, it may overprint earlier, proximal alteration types. Propylitic alteration is peripheral to the higher temperature potassic and sericitic alteration assemblages and is characterized by chlorite, epidote and carbonate. The development of clays in porphyry systems, particularly in telescoped deposits where clays and ore zones are

Chapter 2

intimately associated, is important in mines for primarily two reasons: clays affect rock strength so have significant geotechnical impact on slope stability (Wyllie and Mah

2004) and can significantly influence recovery of copper during mineral processing

(Bulatovic et al. 1998).

1.5.3 Porphyry Cu veinlet relationships

In a general way, the veinlets may be subdivided into three groups : (1) early, quartz- and sulfide-free veinlets containing one or more of actinolite, magnetite (M type), (early) biotite (EB type), and K-feldspar, and typically lacking alteration selvages; (2) sulfide-bearing, granular quartz-dominated veinlets with either narrow or no readily recognizable alteration selvages (A and B types); and (3) late, crystalline quartz-sulfide veins and veinlets with prominent, feldspar-destructive alteration selvages (including D type). Group 1 and 2 veinlets are mainly emplaced during potassic alteration, whereas group 3 accompanies the chlorite-sericite, sericitic, and deep advanced argillic overprints. Narrow, mineralogically complex quartz-sericite-

K-feldspar-biotite veinlets with centimeter-scale halos defined by the same minerals

(±andalusite±corundum) along with abundant, finely disseminated chalcopyrite± bornite characterize the changeover from group 1 to 2 veinlets in a few deposits, although they may have been confused elsewhere with D-type veinlets because of their eye-catching halos; they are termed early dark micaceous (EDM) halo veinlets at Butte

(Meyer, 1965; Rusk et al., 2008a) and Bingham (Redmond et al., 2004), and type 4

(T4) veinlets at Los Pelambres (Atkinson et al., 1996; Perelló et al., 2007). Group 3 also includes uncommon, but economically important massive chalcopyrite± bornite±chalcocite veinlets at the high-grade Grasberg (Pollard and Taylor, 2002),

Chapter 2

Hugo Dum-mett (Khashgerel et al., 2008), and Resolution deposits as well as elsewhere (Figure 1.6).

Figure 1. 6 Schematic chronology of typical veinlet sequences in (a) porphyry Cu-Mo deposits and (b) porphyry Cu-Au de-posits associated with calc-alkaline intrusions Porphyry Cu-Au deposits hosted by alkaline intrusions are typically veinlet poor (Barr et al., 1976; Lang et al., 1995; Sillitoe, 2000, 2002). Background alteration between veinlets is mainly potassic, which is likely to contain more K-feldspar in the Mo-rich than the Au-rich porphyry Cu stockworks. Note the common absence of B- and D- type veinlets from Au-rich porphyry Cu stockworks and M-, magnetite-bearing A-, and chlorite-rich vein-lets from Mo-rich porphyry Cu stockworks. Veinlet nomenclature follows Gustafson and Hunt 1975; A, B, and D types) and Arancibia and Clark (1996; M type).

The alteration terminology used in this chapter is based on Titley (1982) and

Gifkins et al. (2005). Definitions of terms used in this study to describe various alteration assemblages and mineralization features are listed in Table 5.1.

Chapter 2

Table 1. 2 Definitions of alteration and mineralization terminology used in this study; based on Titley (1982) and Gifkins et al. (2005)

Term Definition

Pervasive Alteration that affects all primary minerals; this type of alteration is alteration typically strong or intense and is texturally destructive Selective Alteration in which specific minerals in the host rock and/or alteration porphyry intrusion have been altered; alteration of this type usually preserves or enhances primary rock textures Domainal A type of selective alteration that refers to the alteration of patches, alteration clots, or groups of clasts Vein A fracture ≥ 5 mm wide that is partially or totally in filled by hydrothermal precipitates A fracture ≥ 5 mm wide that is partially or totally in filled by hydrothermal precipitates Veinlet A fracture < 5 mm wide that is partially or totally in filled by hydrothermal precipitates Cement Minerals precipitated in situ from a fluid that bind together clast ± matrix components of a breccia, either as infill of void space or as replacement of clasts or matrix Stringer Wavy veinlets (≤ 5 mm), occurring in a discontinuous sub-parallel pattern that is partially or totally in filled by hydrothermal precipitates Multi-stage A vein that has undergone one or more stages of fracturing and infill vein by hydrothermal precipitates; examples of this style of vein include centerline veins and breccia veins in which fragments of early vein material are cemented by later stages of hydrothermal infill Centerline A multi-stage vein in which fracturing and hydrothermal mineral vein infill occurs along a line of symmetry through the center of the vein; typical of reactivated, symmetrical comb quartz veins that become in filled with sulfide minerals Vein halo Alteration (pervasive or selective) that occurs in the wall rock immediately adjacent to a vein or veinlet Ghosted Primary phenocrysts that are rimmed by alteration minerals causing them to blend in with the surrounding groundmass Weak Alteration in which most crystal edges are visible; crystal cores are alteration typically replaced; this degree of alteration intensity does not modify primary rock textures Moderate Alteration in which most crystal edges are visible and some crystal alteration margins are ghosted; crystal cores are commonly replaced; this degree of alteration intensity partially obscures primary rock textures

Chapter 2

1.5 Thesis Organization

This thesis is divided into 6 chapters. They are structured as follows:

Chapter 1 (Introduction) provides background of research, location of study area, problem statement, objective of research, methodology and thesis organization and Overview on porphyry copper deposit.

Chapter 2 (Regional Geological Setting and Petrography) contains a regional geology, tectonic setting and the intrusive and deposit geology and overview intrusive rocks and volcanic rocks in the Halo prospect. The characteristics of intrusive rocks and volcanic rocks were demonstrated by petrography and observation by hand specimen samples.

Chapter 3 (Lithogeochemistry of Igneous Rocks in Halo Prospect) describes and discuss about the characteristics of the intrusive rocks (major elements, trace elements, and rare earth elements) to constrain petrogenesis and tectonic setting, and lithogeochemistry of intrusive and volcanic rocks to demonstrate elements transportation during hydrothermal alteration at the Halo prospect.

Chapter 4 (Hydrothermal Alteration and Mineralization of Halo Prospect) documents the hydrothermal alteration, vein mineral paragenesis, and mineralization related to the alteration at surface and subsurface (drill holes HD1, HD2, HD3 and

HD4). In this chapter also discus on grade of copper and molybdenum mineralization related to alteration and the occurrence of copper and molybdenum mineralization.

Chapter 5 (Fluid Inclusion Microthermometry and Sulfur Isotopes) presents the fluid inclusion study on quartz with different stages to elucidate ore mineralization with ore forming fluid and sulfur isotope analysis in order to well-understand about source of mineralized fluid at the Halo porphyry copper-molybdenum prospect.

Chapter 2

Chapter 6 (General Discussion and Conclusions) gives general discussion, conclusion and recommendations for further research of Halo porphyry copper- molybdenite prospect.

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contraction and the transport of gold from the porphyry environment to epithermal

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Argentina. Economic Geology, 97(8), 1889-1920.

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251−298.

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palaeogeographic evolution of eastern Tethys. Journal of Asian Earth Sciences, 66,

1-33.

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conditions. Geochimica et Cosmochimica Acta, 52(5), 989-1005.

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2855-2863.

Chapter 2

Chapter 2: Regional Geological Setting and Samples

2.1. Introduction

To study regional geology is an important step for all geologists in mineral exploration. It can provide us the history of the study area such as geological frameworks, tectonic evolution, stratigraphy and lithology and so on. Therefore, this chapter reviews the background information of the tectonic regional setting geology, deposit geology and details of rock unites in the drill hole and on the surface at the

Halo porphyry copper-molybdenum prospect.

2.2. Regional Tectonic Setting and Ore Deposits of Dalat-Kratie Belt (DKB)

Cambodia is located in the southern part of Indochina Terrane, mainland of SE

Asia. The mainland SE Asia comprises several Gondwana-derived terranes including

Indochina, South China, Sibumasu and West Myanmar Terranes, which were assembled and amalgamated by subduction-collision processes during Late

Palaeozoic-Mesozoic time (Metcalfe, 1999, Figure. 2.1). The Indochina Terrane is made up of several tectonic units, which host mineralization belts such as Truong Son

Fold Belt (TSFB), Loei Fold Belt (LFB), Dalat-Kratie Belt (DKB), characterized by magmatic and metamorphic rocks and host a number of mineral deposits (Metcalfe,

2013). The Cenozoic basalts wildly lie within the Indochina Terrance that extends

Chapter 2

from eastern Thailand, Laos, across Cambodia and into southern Vietnam. Along with the North and South China Blocks, the Indochina Terrane rifted away from the northern edge of the Gondwana Supercontinent during the Devonian, resulting in the opening of the Paleotethys seaway (Searle and Morley, 2011). The subsequent

Cenozoic tectonic evolution of Cambodia, and Southeast Asia in general, followed collision between the Indian and Eurasian Plates during the Himalayan Orogeny (55-

45 Ma) and subsequent crustal extrusion before 36 Ma (Khain, 2001; Gibbon et al.,

2015).

The Oyadao South area in NE Cambodia lying on DKB consists of Triassic to

Cretaceous sedimentary rocks intruded by Cretaceous (125-75Ma) volcano-plutonic rocks, which are overlain by Quaternary intraplate basalts. The DKB extends across the region from Cambodia to southern Vietnam and overlies the southern continuation of the TSFB and LFB (Khin Zaw et al., 2010; Figure 2.1). The Cretaceous belt is chronologically comparable to the plutono-volcanic rocks of the late stage of the

Yanshanian Orogeny in SE China (140–65 Ma; Manaka et al., 2012). Thus this belt could have formed in a similar tectonic setting as a southern continuation of the

Yanshanian belt, which was formed from the subduction of the Palaeo-Pacific Plate underneath the Eurasia Plate (including Indochina Terrane) (Thuy et al., 2004; Manaka et al., 2012). The Dalat–Kratie and Southeast China magmatic belts may have been closely associated during the Jurassic-Cretaceous, and were later separated by a

Cenozoic SE Asia extrusion as a result of the Himalaya-India collision (e.g., Hall, 2002,

2011). Ore deposits in the DKB are mostly intrusion-related Au systems (Figure 2.1; e.g., Okvau, Snoul in Cambodia; KhinZaw et al., 2010 and Tien Thuanin Southern

Vietnam; Banks, 2008), porphyry Cu-Au, skarn Pb-Zn, sediment-hosted Au deposits

Chapter 2

(e.g., North Kratie in Cambodia; KhinZaw et al., 2010; Lim, 2012), and porphyry Cu-

Mo, porphyry Cu-Mo-Au porphyry (Canada Wall (CW)) and Okalla East; Angkor

Gold Corp, 2018).

Figure 2. 1 Mineral deposits of Indochina Terrane including Cambodia, Vietnam, Thailand and Laos (modified after KhinZaw et al., 2010).

Chapter 2

2.3 Distribution of Granitic Rocks in South China and Indochina Terrane

2.3.1 Distribution of Granitic Rocks in Cambodia and Dalat-Kratie Belt

The granitic rock in Cambodia as well as granitic rocks in Indochina, particularly

Vietnam were subjected a similar tectonic evolution (e.g Fontaine and Workman,

1978; Carter et al. 2001; Crater and Cliff, 2008). The granitic rocks located at Phnom

Den (including Pha Aok), Ba Phnom,Tamao, Baseth, Kompong Chnang, Phnom

Lung (Rovieng), Kon Mom (Figure 2.2). Based on geochronology age, the granites age at Baseth and Phnom Den was formed in Early Jurassic and Early Cetaceous, respectively (Sitha et al., 2012) and based on Cambodian Projects Location Map and geological map of Halo prospect (Indochina Mining Limited, 2010; Richardson et al.,

2016), granites age at OkVau, Phnom Lung , Kon Mom and Halo was form in Triassic-

Cetaceous. Additionally, all granitic rocks display typical features of I-type granites and was formed in post-Archean subduction-related environment (Sitha et al., 2012).

On the basis of petrographic and mineralogical studies, the granitoids of Dalat in Southern Vietnam were subdivided into three suites: Dinhquan, Deoca and Cana.

Rocks of the Dinhquan suite are hornblende-biotite diorites, granodiorites and minor granites. The Cana suite encompasses mainly leucocratic biotite-bearing granites with scarce hornblende. The Deoca suite is made up of granodiorites, monzogranites and granites. Geochemically, the granitoids are of sub-alkaline affinity, belong to the high-

K, calc-alkaline series, and most of them display typical features of I-type granites.

The Rb–Sr mineral and U–Pb zircon and titanite age data for the granitoids, which establish the ages of the plutonic suites as: the Dinhquan at ~112–100 Ma, Cana at

Chapter 2

~96–93 Ma and Deoca at ~92–88 Ma. Therefore, the Dalat zone began at~112 Ma ago, that is ~30–50 Ma (Thuy et al., 2004).

The granitic rock in Cambodia as well as granitic rocks in Indochina, particularly

Vietnam and South China block were subjected a similar tectonic evolution (e.g

Fontaine and Workman, 1978; Carter et al. 2001; Crater and Cliff, 2008; Jahn et al.,

1990; Chen et al., 2000). The geochronological and geochemical results of the

Yanshanian Orogeny in southeast China and Dalat-Kratie granitoids (southern

Vietnam, southeast and northeast Cambodia), provide evidence for a continuation of an Andean-type arc from southeast China via Dalat-Kratie Belt (Figure 2.1 and 2.3).

Granite gr

Cretaceous -Triassic Halo Cretaceous -Triassicg Cretaceous-Triassic r

OkVau Cretaceousg -Triassic r

Early Jurassic

Early Cretaceous

Chapter 2

Figure 2. 3 Simplified geological map of the Dalat zone shows the distribution of granitoid rocks of the Dinhquan, Cana and Deoca suites (Tien et al., 1991). Letters and number beside solid squares denote sample numbers. The upper inset shows that from mid Jurassic through mid-Cretaceous times the SE Asian margin was an Andean-type arc (Taylor and Hayes 1983). NW-direction subduction beneath the continent is evidenced by wide-spread rhyolitic volcanism and granitic intrusions along SE China (e.g. Jahn et al. 1976) and SE Vietnam.

Chapter 2

2.3.2 Distribution of Granitic Rocks in South China

The Paleo-Pacific Plate beneath the South China Block and surrounding regions was formed as a result of the subduction surrounding the Pacific Ocean that originated from the early Mesozoic. Geochemical and isotopic evidence indicates that the widely distributed Mesozoic (180–90 Ma) I-type granite reflects a subduction-related volcanic arc in southeastern China, known as the Southeast Coast Magmatic Belt (Figure 2.4;

Jahn et al., 1990; Chen et al., 2000). The Late Mesozoic geology of Southeast (SE)

Dalai

Matou

Figure 2. 4 Simpliﬁed geological map of south China showing the distribution of Mesozoic granitoid and volcanic rocks (modiﬁed after Yu et al., 2010; Zhou et al., 2006).

Chapter 2

China is characterized by widespread igneous rocks (>200,000 km2) consisting predominantly of granite, rhyolite, and subordinate maﬁc intrusive and volcanic rocks

(Figure 2.4; Zhou et al., 2006). These igneous rocks comprise two main age groups that are of Jurassic (referred to as “Early Yanshanian” in the Chinese literature) and

Cretaceous (“Late Yanshanian”) ages (Li, 2000; Li et al., 2007; Zhou and Li, 2000).

Previous studies have provided. Late Mesozoic magmatism was largely concentrated in the Cathaysia Block, and the intensity of magmatism in creased towards the ocean

(Figure 2.4) (Zhou et al., 2006). Associated granitoids with Early Yanshanian

(Jurassic) ages are mainly distributed in the in land region, whereas those with Late

Yanshanian (Cretaceous) ages are concentrated in the coastal region. Volcanic rocks were erupted mainly in the Cretaceous and generally crop out along the coast (Zhou et al., 2006). There is a consensus that Cretaceous (Late Yanshanian) magmatism along the coastal area was generated in an active continental margin setting related to subduction of the Palaeo-Paciﬁc Plate (Chen et al., 2008 ; Jahn et al. ,1990; Li et al.,

2007; Zhou et al., 2006). The combined petrological, geochemical, and isotopic features indicate that the Dalai monzodiorites were generated by olivine- and pyroxene-dominated fractional crystallization from basaltic magmas, which were in turn produced by mixing between melts from depleted asthenosphere and subduction- enriched mantle. Matou quartz-monzonites were generated by mixing between mantle- derived maﬁc magmas and crustally derived silicic magmas.

Chapter 2

2.4 Geological Structure of Cambodia

Cambodia, South Vietnam, the southern part of North Vietnam and most of Thailand together comprise part of a well-defined tectonic unit, which may be called the Indochina platform. The southern part of the Indochina platform is the continental shelf extending southwards towards the Indonesian archipelago.

The Indochina platform is a block of continental crust that has remained comparatively rigid since the Jurassic, while younger fold-belts were formed in zones of crustal deformation all around its margin. This post-Jurassic fold belts incorporated parts of a larger block of continental crust that existed after the Indosinian orogeny (Triassic-Jurassic). The principal pre-Cretaceous tectonic units of this landmass are: a core of metamorphic rocks, consolidated before the Devonian, a partial ring of Hercynian (Carboniferous) fold-belts around the core and an outer partial ring of Indosinian (Permian- Jurassic) fold-belts. The oldest rocks of

Indochina are those which make up the metamorphic basement complex formed by Precambrian or early Palaeozoic orogenesis. Part of the basement complex has remained stable (in the sense of not being re-folded) from Devonian to the present day. The eastern part of this stable block of ancient rocks constitutes the

Kontum massif of central Vietnam and adjacent parts of Laos and Cambodia.

Elsewhere, the block subsided during the Palaeozoic was covered by sedimentary formations of neritic or continental facies (Workman, 1997).

In this section the stratigraphic units represented in the geologic succession are described in geochronological order, followed by a section on the intrusive igneous units, according to the general geology of Cambodia is presented in

Geological Map of scale 1:1500 00, which is adapted from the Geological Map of

Chapter 2

Cambodia, Laos, Vietnam, Scale 1:1000000 Phan Cu Tien and et al (1988). In subsequent section, these stratigraphic units and igneous members are placed in a tectonic-metallogenic framework so that the mineral resources data can be understood within the metallogenetic history of the region.

Figure 2. 5 Simplified geological map and principle features of the geological structure of Cambodia (United Nations, 1993).

Chapter 2

The distribution of major stratigraphic-structural groups is shown in Figure

2.5, which is adapted from Fontaine and Workman (1978). This map also indicates some of the major geologic and geographic features.

Around the periphery of the central block of metamorphic rocks were formed in Palaeozoic and early Mesozoic, which was evolved into linear fold- belts. The distinction between stable and geosynclinal areas can be made only where the Triassic and older rocks are exposed, but the pre-Jurassic geology from the Lower

Palaeozoic to the Triassic suggests the existence of a land mass (Annamia) extending over much of central Indochina.

Based on the geological map (Figure 2.5), Ratanakiri province composed of basement rock such as granites and high-grade metamorphic rocks formed during

Precambrian-early Paleozoic, volcano-sedimentary rocks composed of mainly andesitic and rhyolitic, basaltic rocks formed mainly in Neogene-Quaternary, and the

Quaternary sedimentary rocks and unconsolidated sediments. Ratanakiri province has a wide variety of mineral resources such industry minerals and especially metallic minerals such as gold, copper, lead, zinc, iron, manganese, bauxite, tin and tungsten which could be explored and developed in the next future (Southern Gold,

2007).

2.5 The Halo Porphyry Copper-Molybdenum Deposit

The Halo prospect is located on the edge of a monzogranite pluton to the south which is covered with a prominent silica cap outcrops on hilltops in the area. The host rocks of the Halo prospect are composed of felsic and intermediate intrusive and volcanic rocks. The volcanic rocks were intruded by diorite, granodiorite, and a quartz feldspar porphyry stock, which brought copper and molybdenite mineralization in

Chapter 2

veins and veinlets in both the intrusive and volcanic units (Angkor Gold Corp., 2018b).

The quartz feldspar porphyry exposed on the surface is medium to coarse-grained with abundant disseminated sulfides and appears to be the intrusion that brought the molybdenum-copper mineralization. It is typically altered to silica, sericite, or sericite- chlorite (Richardson et al., 2016). Observations of the core indicate that pyrite, molybdenite and chalcopyrite veinlets and veins exposed on surface continue to the bottom of drill holes HD1 and HD2 (Figure 2.6). Drill hole HD1 shows appreciable copper and silver mineralization in the top 99 metres, with anomalous levels of molybdenum corresponding to disseminated sulfides observed in the same interval.

Included in the 99m interval is an intercept of 2,345 ppm Cu, 1.34 g/t Ag, as well as

261.4 ppm Mo over 88.9m which includes 7.9m of 8,043 ppm Cu, 2.24 g/t Ag, and

320.7 ppm Mo from 10.1 to 18.0m (Angkor Gold Corp., 2018b).

A major magnetic, concentrically ringed ‘doughnut’ anomaly is present in the central part of the Halo porphyry copper-molybdenum prospect (Richardson et al.,

2016). This magnetic anomaly is typical expression of a porphyry system with a magnetic high in the center surrounded by a zone of lower magnetic response. The high magnetism typically represents an increase of the abundance of magnetite associated with the mineralization in the center of porphyry type deposit, with

Chapter 2

Figure 2. 6 Lithological map in the Halo prospect with samples location. UTM 48N WGS84, (Richardson et al., 2016)

Chapter 2

surrounding low magnetism which reflects a depletion of the abundance of magnetite in the mineralized host rocks (Barger et al, 2008). Termite mound geochemistry revealed anomalies of copper and molybdenum at the central part of Halo (Figure 2.6) with the high up to 700ppm Cu while the anomaly is generally > 250 ppm Cu, covering

1.5km extending WNW-ESE; 1 km extending NNE-SSW. High anomaly of molybdenum is 400ppm in 1.2km by 75m, extending EW-NS from central part of Halo.

Rock chip geochemistry ranges up to 7,470 ppm Cu and up to 1,450ppm Mo at the central part of Halo (Figure 2.6; Angkor Gold Corp., 2018b). The main alteration zones developed in this prospect on the surface are inner phyllic (sericite), outer phyllic

(sericite-chlorite), argillic (kaolinite-dickite-pyrophyllite-halloysite), propylitic

(chlorite-epidote-quartz-calcite) and silicic quartz alteration according to field observation and short wave infrared spectroscopy (Figure 2.7a; Richardson et al.,

2016). Phyllic alteration is located in the central part of the Halo prospect and was overprinted by silicic alteration (outcrop sample on the hilltops, up to 15m)

(Richardson et al., 2016).

Chapter 2

2.6 Lithology in the Halo Prospect

In order to determine textural and mineral composition of each rock type, a petrographic analysis was conducted on the relatively fresh samples, least altered samples and also altered samples including outcrop samples and drill core samples

(Figure 2.8). The intrusive rocks consist of diorite, granodiorite, quartz feldspar

Chapter 2

porphyry, granodiorite porphyry, hornblende diorite and hornblende granodiorite

(Figures 2.8-2.11, Table 2.1).

2.6.1 Outcrop Samples In the central part of Halo, diorite, granodiorite, andesite and rhyolite were cut by faults trending NE-SW. In the southwestern part of Halo, andesite, rhyolitic tuff, granodiorite and syeno-granite were cut by strike slip fault trending NE-SW, known as Phum Syarung-Dok Yong Fault. Diorite and grandiorite in this study were selected along the stream parallel to a fault trending NE-SW (Figure 2.6). Diorite is dark-gray to greenish light gray in color and medium-grained, and consists mainly of plagioclase

(up to 1.2mm across), quartz (less than 1mm across), K-feldspar (up to 0.8mm long) and biotite (less than 1mm across) (Figure 2.8A, 2.8a). Granodiorite is dark-gray to greenish light gray in color and medium-grained, and consists mainly of anhedral to subhedral plagioclase (up to 1.4mm across), quartz (less than 1.2mm across), minor

K-feldspar and biotite (Figure 2.8B, 2.8b). The degree of alteration in this rock varies from weak to moderate and the original texture is generally preserved. Plagioclase is slightly altered to sericite, and biotite is altered to chlorite in diorite and granodiorite.

Pyrite and chalcopyrite are disseminated in these rocks. Andesite is dark-green in color and fine-grained, and consists mainly of anhedral to subhedral plagioclase (up to

0.3mm across), fine-grained quartz (less than 0.1mm) and hornblende (up 0.2mm across). Plagioclase is commonly replaced by sericite, whereas chlorite and epidote alterations is also widespread (Figure 2.8C, 2.8c).

Chapter 2

2.6.2 Drill Core Samples Drill hole HD1 is composed mainly of dacite and andesite which were cut by numerous pink porphyry dykes (quartz feldspar porphyry), and fine-grained mafic dykes. The rocks in this drill hole are mostly affected by hydrothermal alteration. The majority of alteration in the top 85m is phyllic alteration with patches of weak potassic

Chapter 2

alteration with magnetite. Alteration at the depth from 85 to 155m is dominated by potassic alteration associated with stockworks veinlets, magnetite veinlet, quartz+ magnetite+chalcopyrite veins, and quartz+pyrite+chalcopyrite+magnetite veins and dissemination of pyrite, chalcopyrite and magnetite. The dacite at the depth from 3 to

42m is generally yellowish in color and associated with phyllic alteration that consists of sericite+kaolinite+chlorite based on petrography and XRD analysis (Figure 2.9A,

2.9a). The quartz feldspar porphyry at the depth from 85 to 155m is generally yellow to pink in color and medium to coarse-grained, and consists of euhedral to subhedral phenocrystic plagioclase (up to 8mm across recognized in hand specimen), phenocrystic quartz (up to 2.8mm), groundmass mainly of granular quartz (less than

0.3mm), K-feldspar (less than 0.3mm across), and biotite (up to 1.4mm long), with accessory minerals those include zircon and Fe-Ti oxides (mainly magnetite). The quartz feldspar porphyry is altered with feldspar replaced by sericite, biotite replaced by chlorite, while secondary K-feldspar occurs in groundmass (Figure 3.9B, 2.9b). The andesite is pinkish dark green in color and associated with magnetite veinlets with K- feldspar halo. Hydrothermal biotite occurs as aggregates of fine-grained flakes with quartz and magnetite (Figure 2.9C, 2.9c).

Chapter 2

Figure 2. 9 Photographs (A-C) and photomicrographs (a-c) of selected igneous rocks (A) and (a): dacite in HD1; (B) and (b): quartz feldspar porphyry in HD1; (C) and (c): andesite porphyry in HD1; Abbreviation: pl: plagioclase, Ksp: K-feldspar, hbl: hornblende, bt: biotite, qtz: quartz, ser: sericite, s.bt: secondary biotite, py: pyrite and mag: magnetite.

Drill hole HD2 consists of diorite, granodiorite porphyry with patches of phyllic and weak potassic alteration. Mineralization in this drill hole occurs as quartz+molybdenite veins, quartz+pyrite+chalcopyrite veins, magnetite veinlets, quartz+chalcopyrite+pyrite+magnetite vein, pyrite veinlets and dissemination of

Chapter 2

pyrite and chalcopyrite. The granodiorite porphyry and the diorite were cut by fine mafic dykes, andesitic dykes, aplite dykes, and rhyolite dykes. The granodiorite is dark-gray, pinkish dark-gray, pinkish light green in color, and medium to coarse- grained and consists of euhedral to subhedral phenocrystic plagioclase (up to 7mm

Chapter 2

across), phenocrystic quartz (up to 3.4mm), K-feldspar (less than 0.3mm), biotite (less than 1.4mm across), and hornblende (up to 1.2mm long). Bitotite was partially altered to chlorite and secondary biotite (Figure 2.10).

Drill hole HD3 consists of sheared andesite at the top of the hole and transitioned to granodiorite cut by fine-grained mafic dykes. Alteration consists of phyllic and propylitic alteration. Mineralization occurs as quartz+molybdenite veins, quartz+ pyrite+chalcopyrite+molybdenite veins, quartz+magnetite+chalcopyrite +pyrite veins, quartz+pyrite+chalcopyrite+sphalerite+galena veins and disseminated pyrite and chalcopyrite. The granodiorite is light pinkish green in color, and medium-grained, and consists mainly of euhedral to subhedral phenocrystic plagioclase (up to 2.4mm), phenocrystic quartz (up to 2.4mm), and groundmass mainly of K-feldspar (less than

0.2mm) (Figure 2.11A, 2.11a).

Drill hole HD4 is dominated by unaltered hornblende granodiorite and hornblende diorite, and transitioned into propylitic and phyllic altered diorite cut by massive polymetallic veins consisting dominantly of pyrite, quartz-chalcopyrite- sphalerite-galena veins and quartz-anhydrite-pyrite veins. The hornblende granodiorite and the hornblende diorite were cut by rhyolite dykes, and mafic dykes.

The hornblende diorite is dark-gray in color, and medium-grained, and consists mainly of subhedral to euhedral plagioclase (up 2 mm across), euhedral to subhedral hornblende (up to 1.5mm long), minor quartz (less than 1.2mm across) that fill interstices between hornblende and plagioclase, and trace amount of biotite flakes (less than 0.8mm across). The hornblende granodiorite is light pinkish gray in color, and medium-grained, and consists mainly of subhedral to euhedral plagioclase (up to 1mm across), quartz (less than 1mm across), K-feldspar (less than 0.6mm long), euhedral to

Chapter 2

subhedral hornblende (up to 0.8 mm long). Some plagioclases were altered to epidote

(Figures 2.11B-2.11c).

Chapter 2

Table 2. 1 Summary of petrographic characteristics of intrusive rocks in the Halo prospect

Rock type phenocryst (abundance and size, mm) Groundmass Remarks (size, mm) pl Ksp hbl bt qtz Diorite +++ + + ++ Plagioclase was ± (surface) <1.2 <0.8 <1 <1 slightly altered to sericite and biotite Granodiorite +++ ± ± + ++/+ was altered to - (surface) <1.6 <0.8 <1.2 <0.6 <1.2 chlorite.

Quartz ++ +++/++ ± + +++/++ Medium- Plagioclase was Feldspar <8 <0.4 <1.2 <1.4 <2.8 grained mostly altered k- Porphyry <0.1 feldspar or (HD1) sericite at the rims or in crystal. Hornblende was altered to secondary biotite or chlorite. Granodiorite +++ ++ ± ++/+ + Medium- Plagioclase was Porphyry <7 <0.4 <1.2 <1.4 <3.2 grained altered to feldspar (HD2) <0.1 or sericite. Biotite was altered to chlorite and secondary biotite. Granodiorite +++ ++ - ± ++ Medium- Plagioclase was (HD3) <2.4 <0.2 <0.2 <2.4 grained altered to sericite. <0.1 Biotite was altered to chlorite. Hornblende +++ + ++ - ++ - Plagioclase was diorite <2 0.6 <1.5 <1.2 slightly altered to (HD4) sericite or epidote. Hornblende +++ ++ ++/+ - ++ - Hornblende was Granodiorite <1 0.7 0.6 <1.2 altered to chlorite. (HD4) +++: abundant (>30 % volume), ++: major (10 to 30 %), +: minor (1 to1 %), ±: rare/trace (<1 %), -: not present. Abbreviation: pl: plagioclase, ksp: K-feldspar, hbl: hornblende, bt: biotite, qtz: quartz, H1, H2, H3 and H4: drill hole.

2.7 Conclusions

The Halo porphyry copper molybdenum prospect is hosted in diorite, granodiorite, quartz feldspar porphyry, granodiorite porphyry, andesite porphyry, mafic dykes, andesitic dykes, aplite dykes, and rhyolite dykes. Diorite and granodiorite

Chapter 2

exposed on surface mainly consist of plagioclase, quartz with minor K-feldspar and biotite.

Quartz feldspar porphyry and granodiorite porphyry are exposed at surface and drill hole HD1, and drill hole HD2, respectively. They are medium to coarse-grained, mainly consist of phenocrystic plagioclase, phenocrystic quartz and groundmass of secondary feldspar. The alteration minerals of these rocks are secondary K-feldspar, secondary biorite, sericite and chlorite. The quartz feldspar porphyry and granodiorite porphyry generally contain abundant disseminated pyrite, chalcopyrite, and magnetite.

The degrees of alteration in quartz feldspar porphyry are higher than granodiorite porphyry.

Diorite and granodiorite in drill hole HD3 are similar with diorite and granodiorite at surface. The diorite and granodiorite in drill hole HD3 are associated with mineralization than the diorite and granodiorite at surface. Hornblende diorite and hornblende granodiorite are presented in drill hole HD4. These rocks are mostly unaltered. They are generally composed of plagioclase, quartz and minor hornblende and K-feldspar. The main alteration minerals in these rocks are sericite, epidote, and minor chlorite. Trace pyrite and chalcopyrite are disseminated in these rocks.

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Chapter 3

Chapter 3: Lithogeochemistry of Igneous Rocks in the Halo Prospect

3.1 Introduction

Geochemistry of igneous rocks is commonly used to understand the nature of magmas and tectonic setting of magmatism. A number of ore deposits types are genetically link to magmatism, and thus an understanding the nature of magmas is an important step to establish a deposit model. In this chapter, geochemical analyses were conducted on major elements oxide, trace elements and rare earth elements of intrusive and volcanic rocks in the Halo prospect, aiming to (1) classify igneous unites, (2) constrain the tectonic setting, (3) alteration mineralogy and lithogeochemistry of intrusive and volcanic rocks from the Halo prospect.

3.2 Whole-rock Major and Trace Elements Geochemistry

Whole-rock compositions of 35 intrusive rocks and 7 volcanic rocks from the

Halo prospect (location of sample in Figure 2.4 and 2.4, Chapter 2) are determined

(Table 3.1). The effects of hydrothermal alteration on whole-rock geochemical compositions have been assessed using a combination of petrography and bivariate plots (Figure 3.1a). Thus, samples from the Halo prospect were plotted on an alteration box plot diagram using the alteration index (AI) against the chlorite-carbonate-pyrite index (CCPI) proposed by Large et al. (2001). The alteration index (AI) was calculated by 100 times of the ratio of the sum of K2O and MgO by the sum of K2O, MgO, Na2O, and CaO (Ishikawa et al., 1976). The chlorite-carbonate-pyrite indexes (CCPI) were

Chapter 3

Table 3. 1 Concentrations of major elements oxides (wt. %), trace (ppm) and rare earth elements (ppm) of intrusive and volcanic rocks in the Halo prospect

Depth Outcrop samples D1-12 D1-17 D1-24 D1-28 Samples DIO-1 DIO-2 DIO-3 GRDO- GRDO- GRDO- DC1-1 DC1-2 DC1-3 DC1-4 ID 1 2 3 Rock type Diorite Granodiorite Dacite Alteration LA LA LA LA A LA A-PH A-PH A-PH A-PH Locality Outcrop Drill hole HD1 SiO 2 69.28 (wt. %) 61.01 61.17 61.89 63.31 68.98 64.43 65.56 61.71 63.83

TiO2 0.84 0.86 0.84 0.69 0.55 0.62 0.54 0.52 0.49 0.51

Al2O3 15.67 16.28 15.09 15.58 14.25 15.71 17.96 18.01 15.11 15.67 FeOT 6.77 6.32 6.00 5.73 3.02 5.68 1.95 4.31 2.38 4.48 MnO 0.11 0.13 0.14 0.13 0.04 0.12 0.02 0.04 0.03 0.06 MgO 4.34 4.41 3.81 3.21 2.22 3.22 1.31 2.51 1.64 2.85 CaO 3.94 3.18 4.04 3.01 1.43 2.41 0.06 0.14 0.12 0.15

Na2O 1.87 2.06 1.70 2.03 1.87 2.27 0.41 1.14 1.13 1.41

K2O 2.10 2.19 2.83 2.42 4.19 2.02 7.22 4.95 6.31 4.91

P2O5 0.22 0.22 0.22 0.14 0.09 0.15 0.04 0.03 0.03 0.03 LOI 2.63 2.71 2.44 2.76 2.69 3.19 4.08 4.86 2.34 3.95 Total 99.51 99.55 98.99 99.02 99.32 99.83 99.16 98.22 98.85 97.83 Cu (ppm) 80 60 250 80 413 61 3470 2333 4336 7048 Mo n.d n.d n.d n.d 317 n.d 198 n.d 78 150 Ba 845 850 1038 926 910 432 1298 789 1133 774 Sr 553 507 599 360 236 241 151 163 157 190 Y 29 32 34 33 28 26 35 21 13 16 Zr 225 231 252 157 164 155 216 202 223 146 Rb 64 86 81 72 112 60 123 112 118 99 Nb 7 7 8 5 5 5 9 8 8 6 La 34.82 32.42 35.61 22.99 28.91 13.25 35.13 24.99 12.72 18.10 Ce 81.06 75.22 81.86 52.64 64.70 27.28 76.90 47.20 25.81 35.41 Pr 8.32 7.73 8.42 5.47 6.41 3.43 9.20 5.22 3.09 3.23 Nd 36.20 33.70 36.34 24.72 27.70 12.76 32.57 17.19 10.31 14.61 Sm 6.92 6.55 7.03 5.23 5.32 2.88 6.37 3.32 1.98 2.85 Eu 1.81 1.81 1.83 1.36 1.24 0.74 1.70 0.87 0.60 0.65 Gd 7.58 7.18 8.27 5.85 6.11 3.02 6.04 3.21 1.74 2.21 Tb 0.73 0.66 0.77 0.59 0.62 0.53 0.88 0.48 0.27 0.36 Dy 5.51 5.34 5.90 5.47 5.18 3.25 4.95 2.77 1.44 1.86 Ho 1.04 0.99 1.10 1.03 0.99 0.68 0.96 0.51 0.30 0.35 Er 3.31 3.03 3.34 3.26 3.20 2.16 2.64 1.49 0.89 1.04 Tm 0.38 0.34 0.42 0.39 0.38 0.31 0.35 0.21 0.13 0.13 Yb 3.26 2.96 3.78 3.13 3.37 2.10 2.35 1.43 0.96 0.83 Lu 0.45 0.39 0.46 0.43 0.47 0.31 0.34 0.20 0.15 0.12 Total REE 191.39 178.34 195.11 132.56 154.60 72.70 180.36 109.10 60.40 81.74 (La/Yb)N 7.66 7.86 6.76 5.27 6.16 4.53 10.73 12.53 9.55 15.62 (La/Sm)N 3.25 3.20 3.27 2.84 3.51 2.97 3.56 4.86 4.15 4.10 (Gd/Yb)N 1.92 2.01 1.81 1.55 1.50 1.19 2.13 1.86 1.51 2.20 Eu/Eu* 0.76 0.80 0.73 0.75 0.67 0.77 0.82 0.81 0.96 0.76 Ishikawa AI 52.58 55.75 53.63 52.78 66.04 52.85 94.71 85.37 86.43 83.24 CCPI 73.67 71.65 68.39 66.75 46.33 67.47 29.97 52.87 35.09 53.71 Abbreviation: DIO: diorite on the surface, GRDO: granodorite on surface, DC1: dacite in drill hole HD1, LA: Least altered, A-PH: Phyllic alteration, n.d: not determined.

Chapter 3

Table 3.1 (Cont.)

Depth D1-86 D1-88 D1-89 D1-95 D1-102 D1-111 D1-120 D1-121 D-123 D1-155 Samples QFP1- QFP1- QFP1- QFP1- QFP1- QFP1- QFP1- QFP1- QFP1- QFP1- ID 1 2 3 4 5 6 7 8 9 10 Rock type Quartz Feldspar Porphyry Alteration M-P M-P M-P M-P M-P M-P M-P M-P M-P M-P Locality Drill hole HD1 SiO 2 72.41 72.89 74.50 71.36 74.28 75.60 69.71 73.06 69.23 73.37 (wt. %)

TiO2 0.26 0.30 0.22 0.39 0.29 0.27 0.34 0.32 0.26 0.14

Al2O3 11.99 12.82 11.53 13.49 12.17 10.75 13.77 11.69 13.21 13.03 FeOT 3.11 1.68 2.54 2.71 2.03 2.41 3.07 3.28 4.31 3.19 MnO 0.02 0.01 0.02 0.04 0.03 0.01 0.10 0.03 0.03 0.03 MgO 1.03 1.30 0.94 1.61 1.17 0.91 1.60 1.27 1.29 0.53 CaO 0.09 0.12 0.10 0.21 0.14 0.11 0.13 0.12 0.11 0.07

Na2O 0.95 1.15 1.08 1.66 1.46 1.11 1.48 1.22 1.40 0.81

K2O 6.02 7.16 6.28 6.47 6.70 6.92 6.56 6.36 5.93 6.81

P2O5 0.02 0.03 0.02 0.04 0.02 0.01 0.02 0.02 0.02 0.00 LOI 2.59 1.87 1.75 1.65 1.30 1.29 1.80 1.99 2.80 1.77 Total 98.48 99.34 98.99 99.62 99.59 99.38 98.59 99.37 98.59 99.77 Cu (ppm) 1536 2204 2432 650 769 1274 1669 514 682 152 Mo 80 53 107 41 n.d n.d 34 n.d n.d n.d Ba 797 929 916 1000 877 933 927 859 826 982 Sr 90 174 92 222 177 102 141 126 118 62 Y 10 6 9 13 6 6 7 4 5 4 Zr 124 134 129 156 131 121 133 151 135 98 Rb 117 123 112 111 109 111 129 118 122 128 Nb 4 5 4.00 7.00 5 4 6 5 5 2 La 11.09 8.97 10.17 11.84 8.56 4.29 8.90 5.35 6.59 4.60 Ce 20.56 14.95 19.46 23.00 15.13 7.52 15.55 9.15 11.14 6.76 Pr 2.34 1.67 2.31 2.80 1.74 0.76 1.73 0.91 1.29 0.79 Nd 7.61 4.78 7.41 9.36 5.22 2.75 5.26 3.25 3.81 2.13 Sm 1.48 0.93 1.36 1.85 1.01 0.49 0.99 0.55 0.77 0.42 Eu 0.57 0.47 0.53 0.58 0.49 0.36 0.47 0.39 0.43 0.30 Gd 1.50 0.76 1.22 1.80 0.93 0.51 0.81 0.60 0.68 0.33 Tb 0.22 0.12 0.17 0.26 0.14 0.06 0.14 0.07 0.12 0.07 Dy 1.15 0.55 0.90 1.42 0.75 0.36 0.78 0.35 0.61 0.37 Ho 0.25 0.12 0.17 0.25 0.14 0.11 0.16 0.07 0.10 0.06 Er 0.71 0.32 0.49 0.68 0.42 0.29 0.48 0.25 0.33 0.23 Tm 0.08 0.03 0.06 0.09 0.05 0.04 0.07 0.04 0.04 0.04 Yb 0.63 0.36 0.46 0.62 0.38 0.29 0.55 0.24 0.38 0.34 Lu 0.09 0.05 0.07 0.09 0.06 0.05 0.09 0.05 0.06 0.06 Total REE 48.29 34.07 44.80 54.65 35.02 17.89 35.98 21.26 26.35 16.49 (La/Yb)N 12.56 17.84 15.92 13.70 15.98 10.75 11.54 16.24 12.32 9.64 (La/Sm)N 4.84 6.25 4.82 4.13 5.45 5.66 5.79 6.26 5.50 7.10 (Gd/Yb)N 1.96 1.75 2.21 2.40 1.99 1.48 1.21 2.10 1.46 0.79 Eu/Eu* 1.15 1.67 1.23 0.96 1.51 2.19 1.55 2.07 1.77 2.41 Ishikawa AI 87.14 86.87 85.94 81.23 83.12 86.61 83.60 84.99 82.70 89.30 CCPI 37.26 26.36 32.14 34.70 28.20 29.24 36.75 37.51 43.29 32.81 Abbreviation: QFP1: quartz feldspar porphyry in drill hole HD1, M-P: moderate potassic alteration, n.d: not determined.

Chapter 3

Table 3.1 (Cont.)

Depth D1- D1- D1- D2- D2- D2- D2- D2- D2-313 D2-356 D2-280 99 104 126 187 218 248 273 294 Samples ANP1- ANP1- ANP1- GRDP GRDP GRDP GRDP GRDP GRDP GRDP GRDP ID 1 3 2 2-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8 Rock type Andesite Porphyry Granodiorite Porphyry Alteration M-P M-P M-P W-P W-P W-P W-P W-P W-P W-P W-P Locality Drill hole HD1 Drill hole HD2

SiO2 (wt. %) 65.04 68.18 62.41 66.85 71.52 65.48 66.34 65.39 67.45 65.81 66.33

TiO2 0.52 0.52 0.77 0.36 0.29 0.38 0.38 0.45 0.38 0.41 0.41

Al2O3 15.49 14.82 15.43 11.30 11.76 14.33 13.65 14.79 13.80 14.10 14.13 FeOT 4.67 3.08 6.75 1.66 1.90 2.49 2.71 3.52 3.00 3.42 2.88 MnO 0.04 0.06 0.07 0.02 0.06 0.03 0.10 0.05 0.04 0.06 0.05 MgO 1.87 2.09 2.86 1.56 1.03 1.68 1.44 2.01 1.45 1.57 1.55 CaO 0.26 0.14 0.71 3.63 4.13 2.87 3.39 2.96 3.20 2.96 3.16

Na2O 2.11 1.67 2.14 1.52 1.79 2.10 1.88 2.42 2.07 1.99 2.09

K2O 7.39 7.08 6.00 4.81 3.16 4.50 4.24 3.55 4.34 4.99 4.23

P2O5 0.06 0.03 0.21 0.07 0.08 0.12 0.11 0.14 0.13 0.12 0.13 LOI 1.86 2.08 2.08 5.59 3.83 4.44 4.42 3.55 3.04 3.45 3.82 Total 99.32 99.73 99.42 97.35 99.54 98.40 98.64 98.82 98.89 98.87 98.78 Cu (ppm) 2003 399 371 239 383 558 332 578 481 251 767 Mo n.d n.d n.d n.d n.d n.d 46 n.d n.d n.d n.d Ba 1038 957 719 943 1007 931 953 882 958 1164 1018 Sr 307 197 283 337 221 355 325 487 460 333.00 470 Y 11 8 14 20 20 18 19 21 18 19 18 Zr 134 152 198 133 137 158 170 181 169 150 176 Rb 120 124 111 94 87 97 109 81 98 108 98 Nb 7 8 11 9 6 6 6 7 6 6 6 La 10.78 8.63 9.28 71.36 35.70 25.83 33.45 25.54 33.19 35.13 29.86 Ce 20.59 15.71 19.32 116.25 58.12 48.02 59.90 47.92 61.65 54.06 54.29 Pr 3.16 1.78 2.43 12.90 6.82 5.15 5.68 4.48 6.01 5.47 5.27 Nd 9.08 5.76 8.37 35.95 23.13 15.92 20.31 17.45 21.40 18.62 19.37 Sm 2.43 1.13 1.86 5.46 3.96 2.76 3.41 3.13 3.71 3.00 3.38 Eu 1.41 0.46 0.59 1.24 0.82 0.82 0.85 0.71 0.92 0.75 1.02 Gd 2.33 1.02 1.71 5.66 3.67 2.51 3.26 2.57 3.31 2.68 3.50 Tb 1.03 0.17 0.26 0.62 0.47 0.34 0.42 0.38 0.46 0.34 0.48 Dy 2.20 0.88 1.64 2.93 2.40 1.81 2.25 2.12 2.39 1.74 2.32 Ho 1.15 0.18 0.32 0.55 0.46 0.38 0.43 0.42 0.47 0.34 0.49 Er 1.96 0.50 0.92 1.77 1.48 1.10 1.41 1.31 1.49 1.12 1.51 Tm 1.08 0.12 0.07 0.22 0.20 0.15 0.19 0.18 0.22 0.15 0.22 Yb 1.76 0.52 0.84 1.30 1.33 1.09 1.30 1.24 1.38 0.98 1.37 Lu 1.04 0.08 0.13 0.21 0.21 0.18 0.21 0.20 0.23 0.17 0.23 Total REE 60.00 36.94 47.75 256.42 138.76 106.05 133.06 107.65 136.81 124.54 123.33 (La/Yb)N 4.40 11.98 7.97 39.30 19.22 16.96 18.52 14.79 17.24 25.81 15.58 (La/Sm)N 2.87 4.94 3.22 8.44 5.82 6.04 6.34 5.27 5.78 7.57 5.70 (Gd/Yb)N 1.10 1.63 1.69 3.59 2.28 1.90 2.08 1.72 1.98 2.27 2.11 Eu/Eu* 1.79 1.27 1.00 0.67 0.65 0.93 0.76 0.74 0.78 0.79 0.90 Ishikawa AI 79.61 83.55 75.65 55.32 41.41 55.43 51.86 50.83 52.34 57.00 52.44 CCPI 40.77 37.15 54.14 33.70 37.12 38.72 40.39 48.08 40.95 41.68 41.21 Abbreviation: ANP1: andesite porphyries in drill hole HD1, GRDP2: granodiorite porphyry in HD2, W-P: weak potassic alteration, M-P: moderate potassic alteration, n.d: not determined.

Chapter 3

Table 3.1 (Cont.)

D3- D3- D3- D3- D4- D4- D4- D4- D4- D4- D4- Depth 189 284 78 94 39 224 271 276 277 12 46 DI3- DI3- GRD3- GRD3- HDI4- HDI4- HDI4- HDI4- HDI4- HGRD4- HGRD4- Samples ID 1 2 1 2 1 2 3 4 5 1 2 Hornblende Rock type Diorite Granodiorite Hornblende diorite granodiorite Alteration LA LA LA A-PH LA A-EP LA LA LA LA LA Locality Drill hole HD3 Drill hole HD4 SiO2 (wt. %) 57.78 62.38 69.86 65.99 62.17 62.24 59.46 58.15 59.38 63.01 68.41

TiO2 0.57 0.58 0.35 0.48 0.54 0.53 0.67 0.66 0.67 0.59 0.39

Al2O3 16.08 15.08 12.86 15.20 13.09 11.45 15.64 16.37 16.21 15.37 14.06 FeOT 6.06 4.86 2.13 3.83 6.45 5.89 7.43 7.29 6.11 5.65 3.48 MnO 0.49 0.14 0.44 0.45 0.18 0.15 0.17 0.18 1.13 0.13 0.13 MgO 3.12 3.08 1.45 2.42 2.43 1.70 3.10 3.60 4.64 2.78 1.90 CaO 4.51 3.38 2.73 2.15 9.19 11.90 7.57 7.32 4.65 5.08 3.33

Na2O 2.97 2.55 1.41 1.17 1.49 1.26 1.91 2.08 2.64 2.43 2.94

K2O 1.82 2.59 4.80 4.09 1.50 0.62 1.73 1.97 1.56 2.62 3.04

P2O5 0.15 0.14 0.07 0.07 0.15 0.15 0.18 0.18 0.20 0.15 0.14 LOI 5.64 4.16 3.52 3.69 2.60 3.86 1.86 1.90 1.57 2.00 1.80 Total 99.18 98.94 99.62 99.52 99.79 99.73 99.71 99.71 98.76 99.79 99.63 Cu (ppm) 150 20 250 173 24 15 85 49 68 30 124 Mo 48 12 214 72 n.d n.d n.d n.d n.d n.d n.d Ba 295 584 1037 790 272 165 619 723 411 716 968 Sr 347 295 140 137 1079 1382 523 457 383 385 340 Y 29 23 21 23 27 25 26 22 26 27 20 Zr 83 131 136 155 128 143 117 126 93 128 135 Rb 71 104 124 143 24 13 40 44 56 72 64 Nb 5 5 5 6 5 5 4 4 4 6 6 La 15.87 14.20 25.04 14.75 18.13 20.82 13.82 14.46 14.68 16.11 17.29 Ce 31.69 27.57 45.35 28.64 37.06 40.97 28.59 29.34 31.31 32.75 33.96 Pr 3.55 2.98 4.11 3.18 3.69 4.07 3.40 3.80 3.99 4.08 3.86 Nd 14.19 11.77 16.14 12.03 16.82 17.49 13.89 13.00 14.65 14.58 12.17 Sm 3.21 2.51 3.03 2.69 3.73 3.71 3.35 3.02 3.30 3.61 2.46 Eu 0.71 0.65 0.84 0.72 0.87 0.81 1.15 1.12 0.74 0.97 0.78 Gd 2.73 2.25 2.77 2.47 3.33 3.49 3.25 3.17 3.31 3.49 2.35 Tb 0.53 0.42 0.44 0.50 0.62 0.63 0.71 0.71 0.52 0.61 0.37 Dy 3.22 2.47 2.44 2.77 3.76 3.75 3.30 3.36 3.24 3.72 2.46 Ho 0.68 0.52 0.51 0.62 0.81 0.76 0.82 0.90 0.68 0.83 0.48 Er 2.12 1.60 1.63 1.84 2.51 2.39 2.25 2.35 2.09 2.36 1.43 Tm 0.30 0.23 0.23 0.32 0.36 0.34 0.46 0.55 0.28 0.38 0.21 Yb 2.06 1.54 1.58 1.77 2.40 2.34 2.14 2.22 2.08 2.21 1.55 Lu 0.32 0.24 0.26 0.34 0.36 0.35 0.46 0.52 0.29 0.37 0.23 Total REE 81.17 68.93 104.37 72.67 94.47 101.93 77.58 78.51 81.16 86.09 79.62 (La/Yb)N 5.54 6.63 11.39 5.97 5.42 6.39 4.63 4.67 5.07 5.22 7.99 (La/Sm)N 3.19 3.65 5.34 3.54 3.14 3.62 2.66 3.09 2.87 2.88 4.53 (Gd/Yb)N 1.10 1.21 1.46 1.15 1.15 1.24 1.25 1.18 1.32 1.30 1.25 Eu/Eu* 0.71 0.82 0.88 0.84 0.74 0.68 1.05 1.10 0.68 0.82 0.98 Ishikawa AI 39.73 48.92 60.14 66.25 26.87 14.94 33.78 37.19 45.95 41.80 44.08 CCPI 65.70 60.72 36.58 54.31 74.77 80.15 74.29 72.86 71.88 62.55 47.34 Abbreviation: DI3 and GRD3: diorite and granodiorite in HD3, HDI4 and HGRD4: hornblende diorite and hornblende granodiorite in drill hole HD4, LA: Least altered, A-PH: phyllic alteration, A-EP: propylitic alteration, n.d: not determined.

Chapter 3

calculated by 100 times of the ratio of the sum of MgO and FeO by the sum of MgO,

FeO, Na2O, and K2O. All major elements used to calculate AI and CCPI are expressed as wt. %. The samples plotted on the alteration box plot diagram display (1) moderate

K-feldspar-sericite, (2) sericite, (3) sericite-chlorite-pyrite, and (4) weak epidote- calcite±albite alteration trends. However, the majority of the samples do not significantly deviate from the least-altered box (Figure 3.1a).

LOI (loss on ignition) values of least altered rocks range from 1.5 to 5.6%, while

LOI values of the altered rocks range from 1.3 to 4.8%. Some of altered rocks have the LOI value higher than least altered because the rocks are potassic alteration, therefore the LOI is not so high. Thus the LOI values may misclassify between least altered and altered sample in this study. The result of least altered rocks classified by box plot (Large et al., 2001) are consistent with the petrography. The SiO2 concentrations of intrusive rocks and volcanic rocks in the Halo prospect range from

57.7 to 75.6 wt. % and 61.7 to 68.2 wt. %, respectively. The (Na2O+K2O) versus SiO2 diagram (Cox et al., 1979) indicates that the intrusive rocks in the Halo prospect are classified as diorites, granodiorites and granites (quartz feldspar porphyry) (Figure

3.1b). A high field strength element (HFSE) bivariate plot of Zr/TiO2–Nb/Y

(Winchester and Floyd, 1976, 1977) is used to distinguish geochemically the various volcanic rocks from the Halo prospect (Figure 3.2a). The volcanic rocks plot in rhyodacite/dacite to trachyandesite fields. The rocks classifications are reliable for diorite and granodiorite as they are the least altered. The quartz feldspar porphyry spatially associated with mineralization, show strong alteration in the box plots.

Therefore, major elements are deemed unreliable to classify the rock types as strongly altered.

Chapter 3

On the SiO2 versus K2O discrimination diagram for intrusive and volcanic rocks (Figure 3.2b), intrusive rocks are medium-K calc-alkaline, high-K calc-alkaline and shoshonitic fields (Peccerillo and Taylor, 1976). The samples with high-K values contain hydrothermal K-feldspar and biotite, implying that K was added to the rocks during hydrothermal alteration (potassic alteration). Thus, it is interpreted that the high-K trend is a result of potassic alteration and does not reflect primary igneous composition (e.g., shoshonite). The least altered granodiorite (GRDP2) plots in high-

K calc-alkaline to shoshonite. Therefore, the primary igneous compositions of rock belong to the high-K calc-alkaline series. The least altered diorite and granodiorite exposed on surface plot in medium-K to high-K calc-alkaline field. Thus the primary composition of diorite and granodiorite belongs to medium-K calc-alkaline series.

Diorite and granodiorite (DI3 and GRD3) plot on boundary between medium-K and high-K calc-alkaline field. Least altered hornblende diorite (HDI4) plots in medium-

K calc-alkaline field except one sample with strong alteration plot in low-K calc- alkaline filed. The primary igneous compositions of the hornblende diorite belong to the high-K calc-alkaline series. In contrast, low-K composition is also affected by hydrothermal alteration. The granodiorite (HGRD4) plots on boundary between medium-K to high-K calc-alkaline, is close to primary igneous rock compositions.

Based on the box plot and SiO2 versus K2O (wt. %) diagram, some samples are strongly affected by K mobility. Therefore, we further use Pearce element ratios (PER) analysis to discuss in next section in order to elucidate about alteration lithogeochemistry (Pearce, 1986). Classification of rocks based on the ASI (alumina saturation index =A/CNK [Al2O3/(CaO+K2O+Na2O)]) (Figure 3.1c) (Maniar and

Piccoli, 1989) indicates that granodiorite porphyry (GRDP2), diorite (DI3),

Chapter 3

granodiorite (GRD3), hornblende diorite (HDI4) and hornblende granodiorite

(HGRD4) are metaluminous field. The ASI values less than 1.1 suggest that granitoids in this area predominantly I-type granite afﬁnity (Chappell and White, 1974).

Magnetic susceptibility of hornblende diorite (three samples), hornblende granodiorite

(1 sample) and granodiorite porphyry (4 samples) range from 20.3 to 28.0×10-3 in SI unite, 17.20 ×10-3 in SI unite and 3.5 to 6.8×10-3 in SI unite, respectively, corresponding to magnetite series (>3×10-3 in SI unite, Ishihara, 1977). Moreover, these rocks show a marked decrease in P2O5 when the SiO2 contents are increase

(Figure 3.3h), are considered as the fractionated I-type granite. They lack aluminous minerals (e.g., muscovite, tourmaline and garnet), but have magmatic assemblage of amphibole and biotite (Figure 2.5-2.8 in chapter 2), which are consistent with features of I-type granite (Chappell and White, 1992; Barbarin, 1999). These characteristics indicate that the Halo prospect intrusive complex represents I-type magmatism.

Additionally, based on diagram FeOt/MgO versus SiO2 (Figure 3.2c), the intrusive and volcanic plot in calc-alkanie series, even though quartz feldspar porphyry, dacite and andesite are altered rocks but the results are closely with fresh and least altered rocks.

Thus, the result are reliable to use.

Chapter 3

Al2O3/(CaO+K2O+Na2O)] versus A/NK [=molar Al2O3/(K2O+Na2O)] diagram (Chappell and White, 1974; Maniar and Piccoli, 1989). Abbreviation: DIO: diorite on the surface; GRDO: granodorite on surface; QFP1: quartz feldspar porphyry in drill hole HD1, GRDP2: granodiorite porphyry in HD2; DI3 and GRD3: diorite and granodiorite, respectively, in HD3, HDI4 and HGRD4: hornblende diorite and hornblende granodiorite, respectively, in drill hole HD4.

Chapter 3

Figure 3. 2 (a) Zr/TiO2versus Nb/Y diagram derived for volcanic rocks of (Winchester and Floyd, 1976, 1977), (b) SiO2 versus K2O (wt. %) diagram of (Peccerillo and Taylor,

1976), (c) FeOt/MgO versus SiO2 diagram (Miyashiro, 1974). Abbreviation: DC1and ANP1: dacite and andesite porphyry, respectively, in drill hole HD1 and other symbols are the same as in Figure 3.1.

Chapter 3

Figure 3. 3 Bivariate plots of SiO2 versus selected major elements. (a) SiO2 vs TiO2, (b). SiO2 vs FeO, (c) SiO2 vs Al2O3, (d). SiO2 vs MnO, (e) SiO2 vs MgO, (f) SiO2 vs CaO, (g) SiO2 vs Na2O (h) SiO2 vs P2O5 of the different lithological units from the Halo prospect. Abbreviation: DIO-1 to DIO-3 and GRDO-1 to GRDO-3: diorite and granodiorite, respectively, exposed on surface; DC1-1 to DC1-4, ANP1-1 to ANP1-3, and QFP1-1 to QFP1-10: dacite, andesite porphyry and quartz feldspar porphyry, respectively, in drill hole HD1; GRD2-1 to GRD2-8: granodiorite porphyry in drill hole HD2; DI3-1 to DI3-2 and GRD3-1 to GRD3-2: diorite and granodiorite, respectively, in drill hole HD3; HDI4-1 to HDI4-5 and HGRD4-1 to HGRD4-2: hornblende diorite and hornblende granodiorite, respectively, in drill hole HD4. Locations are shown in Figures 2.3 and 2.4

Bivariate diagrams for selected major elements versus SiO2 are shown in Figure

3.3. The TiO2, FeO, MnO, MgO, P2O5 contents decrease as the SiO2 contents increase

(Figures 3.3a, 3.3b, 3.3d, 3.3e and 3.3h), suggesting igneous fractional crystallisation processes (Wilson, 1989). However, Al2O3 content is poorly correlated with SiO2, while K2O, CaO, and Na2O are scattered (Figure 3.2b, 3.3f and 3.3g), this may be

Chapter 3

explained by element mobility during hydrothermal alteration. The K2O contents of quartz feldspar porphyry, andesite and dacite are high ranging from 4.9 to 7.4 wt. % with low CaO and Na2O contents ranging from 0.06 to 0.70 wt. % and 0.41 to 2.14 wt. %, respectively. They are strongly altered (Figure 3.1a), it means that K2O gained while CaO and Na2O were lost during potassic and phyllic alteration.

Bivariate diagrams for selected trace elements versus SiO2 are shown in Figure

3.4. Concentrations of high field strength (HFS) cations (eg.,V, Zr, and Sc) of intrusive and volcanic rocks decrease as SiO2 content increase (Figure 3.4a, 3.4e, and 3.4f). A similar antithetic relationship is shown between the large ion lithophile (LIL) elements

(eg., Sr, Ba, and Rb) and SiO2 (Figure 3.4b-3.4d). These mobile LIL elements are considerably scattered than the HFS cations, which is excepted since LIL elements are more mobile to secondary processes. Cu concentrations of dacite, quartz, feldspar porphyry and andesite range from 2,333 to 7,048ppm, 152 to 2,432ppm and 371 to

2,003ppm, respectively. Cu content of granodiorite porphyry ranges from 239 to

767ppm. For diorite, granodiorite, hornblende diorite and hornblende granodiorite of less altered samples, Cu content ranges from 15 to 85ppm, in contrast for moderate altered sample of diorite and granodiorite in which the Cu content ranges from 150 to

413ppm. Based on box plot diagram and petrography, the Cu concentration of altered sample is high compared to the less altered samples. The highest Cu concentration is associated with phyllic alteration hosted in dacite. Mo concentration of diorite, granodiorite, quartz feldspar porphyry and granodiorite porphyry are generally lower than 214ppm (Table 3.1and Figure 3.4g-3.4h). The linear variation in NaO2+KO2 vs

SiO2, TiO2 vs V, Zr/TiO2 vs SiO2 and various major elements suggests that igneous rocks are co-magmatic (Figures 3.3 and Figure 3.4i–3.4k).

Chapter 3

Figure 3. 4 Bivariate plots of SiO2 versus minor elements, (a) SiO2 vs Zr, (b) SiO2 vs Rb (c) SiO2 vs Sr, (d) SiO2 vs Ba, (e) SiO2 vs Sc, (f) SiO2 vs V, (g) SiO2 vs Cu, (h) SiO2 vs Mo, (i) NaO2+KO2 vs SiO2, (j) TiO2 vs V and (k) Zr/TiO2 vs SiO2 . Symbols are same as Figure 3.3.

3.3 REE Geochemistry of intrusive rocks

The concentration of rare earth element (REE) and other trace elements of intrusive and volcanic rocks are given in Table 3.1. Chondrite-normalized REE patterns (Sun and McDonough, 1989) of the intrusive and volcanic rock from the Halo prospect (diorite, granodiorite, granodiorite porphyry, quartz feldspar porphyry, dacite and andesite) show general enrichment of light REEs (LREE) ((La/Yb)N) = 4.4 to 39.3) and depletion of heavy REEs (HREE) ((Gd/Yb)N = 0.79 to 3.59) (Figure 3.5). Distinct weakly negative Eu anomaly (Eu/*Eu = 0.65 to 0.98) of diorite, granodiorite, and granodiorite porphyry would be indicative of removal of plagioclase (Davidson et al,

2013). Quartz feldspar porphyry, dacite and andesite porphyry characterized by negative to positive Eu anomalies (Eu/*Eu = 1.15 to 2.41). Negative of Eu anomalies possible fractionation of Eu to plagioclase, while the positive Eu anomalies suggest that Eu present in primary plagioclase is immobile during potassic alteration, while other REE were slightly removed during potassic alteration. Thus, REE patterns were slightly mobile during alteration. The primitive mantle-normalized trace elements

Chapter 3

diagram of intrusive and volcanic rocks in Halo are characterized by enrichments of large-ion lithophile elements (LILE, such as K, Rb and Ba) and depletions of high field strength elements (HFSE, such as Nb and Ti) (Figure 3.5).

Quartz feldspar porphyry samples (QFP1-1 to QFP1-4) contain higher total REE concentration ranging from 44.8 to 54.6 ppm compared to quartz feldspar porphyry samples (QFP1-5 to QFP1-10) ranging from 16.4 to 35.9ppm. Based on petrography, all quartz feldspar porphyries are potassicaly altered and samples QFP1-1 to QFP1-4 are less altered than the samples QFP1-5 to QFP1-10. This suggests that the REE were slightly removed during potassic alteration, except for Eu which was accommodated in plagioclase and immobile during potassic alteration.

Chapter 3

Figure 3. 5 Chondrite-normalized rare earth element and primitive-mantle-normalized trace element patterns of intrusive and volcanic rocks in the Halo prospect (Sun and McDonough, 1989). Symbols and abbreviations are the same as Figure 3.3

Chapter 3

3.4 Molar Element Ratios

General element ratios (GERs) and Pearce element ratios (PERs) are both molar element ratios (MERs) used to depict geochemical processes such as alteration

(Pearce, 1986; Stanley and Russell, 1989). PER analysis uses molar element concentrations ratio to the molar concentration of an element which has remained unchanged during mass transfer processes, i.e. a ‘conserved’ element (Stanley and

Madeisky, 1994; Stanley and Madeisky, 1995). Thus in order to quantify the intensity of hydrothermal alteration around major mineralized zones, it is necessary to use a technique that distinguish the metasomatic impact of the mineralizing ﬂuids, a prerequisite for which is pre-existing geochemical heterogeneity in the host rocks. It is also necessary to discriminate between the effects of hydrothermal activity and other events such as weathering or metamorphism. A conserved element must be identified for use as a denominator in the PERs. Conserved elements are also used to test the cogenetic character of the rocks and group them accordingly. A PER diagram of Pr versus Nd shows the same behavior during alteration and a best-fit line with a positive slop that intersects the origin indicating that the rocks are derived from a single precursor (Figure 3.6a; MacLean and Barret, 1993). The samples are cogenetic, thus

PER can be adapted (Stanley and Madeisky, 1994).

A PER plot of (2Ca+Na+K) versus Al/Nd (Figure 3.6b) discriminates between unaltered and hydrothermally altered felsic rocks. The least altered samples plot closer to the feldspar-plagioclase control line with slop of 1 from the origin while the completely sericitized samples plot closer to the line with slop of 1/3 from the origin

(Urqueta et al., 2009). The dacite samples plot around and toward the muscovite

Chapter 3

control line with slop of 1/3, suggesting the dacite has been affected by quartz-sericite- pyrite (phyllic) alteration (Figure 3.6b) while the quartz feldspar porphyry, andesite porphyry, diorite and granodiorite samples plot between the plagioclase and the muscovite control lines, suggesting that these rocks have been affected by varying degree of sericite alteration. This is consistent with plagioclase replaced by sericite

Chapter 3

observed in petrography. Potassic alterations such as secondary biotite or secondary

K-feldspar in rocks are not discriminated from unaltered rocks on this diagram.

Epidote alteration is represented by the control line with slope of 16/3. The hornblende diorite samples plot between the epidote and plagioclase control lines consistent with petrography and XRD analysis.

3.5 Discussion

3.5.1 Genetic implication The enrichment of LILEs and depletion of Nb and Ti is characteristic feature of magmas generated in a subduction-related tectonic setting (Wood et al., 1979; Briqueu et al., 1984). The low Nb depletion is typical of calc-alkaline magmatic rocks formed in subduction zone environments and may be regarded as an indicator of crustal involvement in magmatic process (Rollinson, 1993; Lan et al., 1996). Moreover, in the

(Y+Nb) versus Rb, and Y versus Nb diagrams (Figure 3.7a and 3.7b; Pearce et al.,

1984), samples plot within the field of volcanic arc granite. Furthermore, Rb/Zr vs. Nb diagram, the intrusive rocks plot within island arc setting (Figure 3.7c). It is consistent

Chapter 3

Figure 3. 7 (a), (b) tectonic discrimination diagrams for plutonic rocks (Pearce et al., 1984), (c) Rb/Zr vs. Nb diagram (Brown et al., 1984), VAG: volcanic-arc granite, COLG: syn-collision granite, WPG: within plate granite, ORG: oceanic ridge granite. Symbols and abbreviations are the same as Figure 3.3. with the lithochemistry of porphyry copper-(molybdenum-gold) deposits formed by magmatic-hydrothermal fluids generated from subduction related magmatism.

Chapter 3

3.5.2 Tectonic Affinity and Petrogenesis The fresh and least-altered diorite and granodiorite were selected to discriminate between typically arc rocks and arc adakite. In the commonly used Sr/Y versus Y diagram, the diorite and granodiorite dominantly plot in typical arc (Figure 3.8a;

Defant and Drummond, 1990). This result is consistent with relatively unfractionated

HREE patterns of the samples plotted in Figure 3.2. Furthermore, based on the

(La/Yb)N versus YbN diagram, the diorite and granodiorite plot in the field of post-

Archean subduction-related granitoids (Figure 3.8b; Martin, 1986). This is in the good agreement with the conclusion of Taylor and Hayes, (1983) who assumed that the

Southeast Asian margin was an Andean-type magmatic arc (subduction of the western Pacific plate under the south-east Asian continental margin) from mid-

Jurassic to mid-Cretaceous. Y versus Sr/Y diagram and La/YbN versus YbN diagram show that the intrusive rocks plot in the post-Archean subduction-related granitoids or slab-dehydration post-Archean granitoids. As a whole, the intrusive rock in the Halo prospect are less contaminated with the continental crust and fractionated in higher oxidized condition compared with other porphyry deposit such as Qulong porphyry copper-molybdenum deposit (Xiao et al., 2011), porphyry copper deposit in El

Salvador (Cornejo et al., 1997). Therefore, low (La/Yb)N ratios in the Halo prospect rule out considerable amounts of fractionated amphibole from a hydrous magma.

Chapter 3

Figure 3. 8 Discrimination diagram for the origin of intrusive rocks in the Halo prospect and (a) plot Y (ppm) versus Sr/Y diagram with fields from (Defant and

Drummond, 1990), (b) plot of La/YbN versus YbN with fields from (Martin, 1986), ;

(c) (La/Yb)N versus MgO diagram, average crustal thickness, on the basic of (La/Yb)N ratio is from (Ahmadian et al., 2009) (d) (A) Rb/Nd versus Rb diagram (after Schiano et al., 2010); (e) (C) Plot of Al2O3 +FeO +MgO +TiO2 versus Al2O3/(FeO + MgO +

TiO2) (after Patiño Douce, 1999 ). Symbols are the same as in Figure 3.1.

Considering La/Yb as a crustal thickness proxy in intermediate to felsic calc- alkaline rocks prospect, arc crustal thickness in Halo prospect was probably <40 km at the time of emplacement of normal calc-alkaline granitoids (Figure 3.8b and 3.8c).

Chapter 3

Additionally, the samples trend in the plots of Rb/Nd versus Rb diagram (Fig. 3.8d) also suggest that hybrid magma mixing probably is the dominant factor in the magma evolution. Their low contents of TiO2 <1.0 wt. % (least altered rocks), high content of

Y >15 ppm) and strong depletions of HFSE (Nb, Ti) are similar to arc magmas (Figure

3.5), suggesting a source of hydrous mantle wedge metasomatized by slab derived fluids (Tasumi et al., 1986; Schmidt et al., 2004). Moreover, intrusive rocks have low

Al2O3/(FeO+MgO+TiO2) ratios and fall into field of partial melting of amphibolite

( Figure 3.8e) (Patiño Douce, 1999), further indicating that they were mainly derived from partial melting of basaltic meta-igneous rocks.

3.5.3 Alteration Lithogeochemistry In the PER diagram (2Ca+Na+K)/Nd versus Ca/Nd (Figure 3.6b), quartz feldspar porphyry and andesite porphyry are only moderately altered while dacite exhibits the highest alteration indices. Rock units with highest alteration are indicated by sericite alteration. Moreover, the behaviour of K during alteration can be broadly understood in the PER diagram of K/Al versus (2Ca+Na+K)/Al for felsic lithologies

(Figure 3.9b; Urqueta, 2009). These diagrams spatially provide the location of the main alteration minerals by discriminating between potassic, sericite and argillic alteration for felsic and intermediate lithologies. The least altered rocks plot closer to

(1, 0) while potassic alteration mineral (K-feldspar and biotite) plot towards the (1, 1), muscovite plot at (1/3, 1/3) and kaolin group minerals and chlorite plot at (0, 0).

General and Pearce element ratios can identify the three alterations in the Halo prospect such as potassic (secondary K- feldspar and biotite), phyllic (sericite) and propylitic (epidote) alteration. Results are also consistent with petrography (Figures

2.5-2.8, in Chapter 2 and Figure 3.9).

Chapter 3

Pearce Element Ratios (PERs) diagrams can discriminate between the effects of hydrothermal activity and other events such as weathering or metamorphism.

Moreover, these diagrams also can determine the alteration index (AI) by identifying the slop of the line connecting the sample point and its origin. AI is defined by dividing the ordinate value (y-axis) with absicca value (x-axis) (Urqueta et al., 2009). AI values were rescaled so that a value of 1, representing AI of an unaltered samples as 0%, and

AI of totally altered rocks as 100%. AI of the quartz feldspar porphyry and the andesite porphyry associated potassic alteration ranges from 11.8 to 32.3% and that of the dacite associated with phyllic alteration ranges from 43.3 to 66.6% while that of two samples of granodiorite porphyry ranges from 5.1 to 11.9%. The potassic alteration within the quartz feldspar porphyry, andesite porphyry and granodiorite porphyry are accompanied with high grade of copper up to 2,670 and molybdenum up to 5,297ppm.

Chapter 3

Moreover, the high grade of copper up to 7048 ppm associated with phyllic alteration that hosted in dacite with high AI.

3.6 Conclusions

The diorite and granodiorite belong to medium-K calc-alkaline to high-K calc- alkaline series while rock-series of volcanic rocks and quartz feldspar porphyries were not determined due to the mobility of K during alteration. The intrusive rocks in the

Halo prospect display features of trace elements typical of the magmatism related to a subduction zone, such as enrichment of LILE and negative anomalies of Nb and Ti.

The intrusive rocks and volcanic rocks plot within the domains of volcanic arc granite based on spider diagram, (Y+Nb) versus Rb diagram, and Y versus Nb diagram.

General element ratios and Pearce element ratios (PER) define three alterations in the

Halo prospect such as potassic (secondary K-feldspar and biotite), phyllic (sericite)

Chapter 3

and propylitic (epidote) alteration. The alteration index of the dacite and the quartz feldspar porphyry calculated from PER are higher than that of the granodiorite porphyry. This is consistent with the high copper concentration of the dacite and the quartz feldspar porphyry up to 7,048 ppm.

References

Ahmadian, J., Haschke, M., McDonald, I., Regelous, M., RezaGhorbani, M., Emami,

M. H., & Murata, M. (2009). High magmatic flux during Alpine-Himalayan

collision: Constraints from the Kal-e-Kafi complex, central Iran. Geological

Society of America Bulletin, Vol. 121, pp.857-868.

Briqueu, L. and Bougault, H. Joron, J. L. (1984) Quantification of Nb, Ta, Ti and V

anomalies in magmas associated with subduction zones-petrogenetic implications,

Earth and Planetary Science Letters, Vol.68, pp. 297-308.

Brown, G.C., Thorpe, R.S., Webb, P.C., 1984. The geochemical characteristics of

granitoids in contrasting arcs and comments on magma sources. J. Geol. Soc.

Lond. Vol.141, pp. 413 –426.

Cox, K. G., Bell, J. D. and Pankhurst, R. J. (1979) The interpretation of igneous rocks,

George Allen and Unwin Boston, London. 450p.

Davidson, J., Turner, S. and Plank, T. (2013) Dy/Dy*: Variations Arising from Mantle

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Defant, M. J. and Drummond, M. S. (1990) Derivation of some modern magmas by

melting of young subducted lithosphere, Nature, Vol. 347, pp. 662-665.

Chapter 3

Lan, C. Y. J., Jahn, B. M., Mertzman, S. A. and Wu, T. W. (1996) Subduction-related

granitic rocks of Taiwan, Journal Southeast Asian Earth Science, Vol. 14, pp. 11-

28.

Large, R. R., Gemmell, J. B., Paulick, H. and Huston, D. L. (2001) The alteration box

plot: A simple approach to understanding the relationships between alteration

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MacLean, W. H. and Barrett, T. J. (1993) Lithogeochemical techniques using

immobile elements, Journal of Geochemical Exploration, Vol. 48, pp. 109-133.

Martin, H. (1986) Effect of steeper Archean geothermal gradient on geochemistry of

subduction-zone magmas, Geology, Vol. 14, pp. 753-756.

Maniar, P.D., Piccoli, P.M., 1989. Tectonic discrimination of granitoids. Geological

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Douce, A. E. P. (1999). What do experiments tell us about the relative contributions

of crust and mantle to the origin of granitic magmas?. Geological Society, London,

Special Publications, Vol, 168, pp. 55-75.

Pearce, J. A., Harris, N. B. W. and Tindle, A. G. (1984) Trace element discrimination

diagrams for the tectonic interpretation of granitic rock, Journal of Petrology,

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Pearce, T. H. (1986) A contribution to the theory of variation diagrams, Contribution

to Mineral and Petrology, Vol. 19, pp.142-157.

Peccerillo, A. and Taylor, S. R. (1976) Geochemistry of Eocene Cal-Alkaline Volcanic

Rocks from the Kastamonu Area, Northern Turkey, Contributions to Mineralogy

and Petrology, Vol. 58, pp. 68-81.

Chapter 3

Rollinson, H. R. (1993) Using Geochemical Data: Evaluation, Presentation, and

Interpretation, Longman Scientific and Technical, Singapore. 352p.

Stanley, C. R. and Madeisky, H. E. (1995) Lithogeochemical exploration for

hydrothermal mineral deposits using Pearce Element Ratio diagrams, In:

Extended Abstracts, 17th IGES, 15–19 May, Townsville, Queensland, pp. 259–

262.

Stanley, C. R. and Madeisky, H. E. (1994) Lithogeochemical exploration for

hydrothermal ore deposits using Pearce Element Ratio analysis. In: Lentz, D.R.,

(Ed.) Alteration and alteration processes associated with ore-forming systems. In

Short Course Notes of Geological Association of Canada, Vol.11, pp.193-212.

Stanley, C. R. and Russell, J. K. (1989) Petrologic Hypothesis Testing with Pearce

Element Ratio Diagrams: Derivation of Diagram Axes, Contributions to

Mineralogy and Petrology, Vol. 103, pp. 78-79.

Schiano, P., Monzier, M., Eissen, J.P., Martin, H., Koga, T., 2010. Simple mixing as

the major control of the evolution of volcanic suites in the Ecuadorian Andes.

Contrib. Mineral. Petrol, Vol, 160, pp. 297–312

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basalts: implication for mantle composition and processes. In Saunder, A. D. and

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The tectonics and geologic evolution Southeast Asian seas and islands, part 2”, in

Geophysical Monograph 27, D.E. Hayes, eds: American Geophysic Union,

Washington, pp. 23-56.

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Urqueta, E., Clark, A.H., Stanley, C. R., Oates, C. J. and Kyser, T. K. (2009)

Lithogeochemistry of the Collahuasi porphyry Cu–Mo and epithermal Cu–Ag (–

Au) cluster, northern Chile: Pearce element ratio vectors to ore, Geochemistry:

Exploration, Environment, Analysis, Vol. 9, pp. 9-17.

Winchester, J. A. and Floyd, P. A. (1977) Geochemical Discrimination of Different

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to classify and discriminate between magma series erupted in different tectonic

settings, Earth and Planetary Science Letters, Vol. 68, pp. 297-308.

Chapter 4

Chapter 4: Hydrothermal Alteration and Mineralization of the Halo Prospect

4.1 Introduction

This chapter documents the hydrothermal alteration, vein mineral paragenesis, and mineralization related to the alteration at surface and subsurface (drill holes HD1,

HD2, HD3 and HD4).

4.2 Wall Rock Alteration

4.2.1 Surface Hydrothermal fluids produced various hydrothermal alteration zones across the pluton, including potassic, phyllic, propylitic, argillic and silicic alteration. The main alteration zones developed in this prospect on the surface are inner phyllic (sericite), outer phyllic (sericite-chlorite), argillic (kaolinite, dickite-pyrophyllite-hallosyite), propylitic (chlorite-epidote-quartz-calcite) and silicic alteration (quartz) according to field observation and SWIR interpretation. Phyllic alteration is distributed the central part of the Halo prospect and was overprinted with silicic alteration (outcrop sample on the hilltops, up to 15m, Figure 2.4 in chapter 2). To clarify the alteration zoning,

XRD analysis and petrographic analysis were conducted on 24 samples in this study

(Table 4.1, Appendix 1). Quartz vein cutting silicified rock and quartz bearing pyrite exposed at the hilltop near drill hole HD3 and HD1, respectively, in silicic zone

Chapter 4

(Figures 4.1A-4.1b). Quartz+pyrite+chalcopyrite+goethite vein cutting granodiorite associated with phyllic alteration along the fault trending NE-SW (Figures 4.1C, 4.1c).

Quartz+molybdenite vein cutting granodiorite associated with phyllic alteration near the drill hole HD3 with high concentration of molybdenum about 6537ppm (Figures

4.1D, 4.1a). Under the microscope, sericite alteration halos surround quartz+molybdenite+pyrite vein, while plagioclase was transformed into sericite with groundmass quartz (Figures 4.2a-4.2c). Moreover in granodiorite, K-feldspars and plagioclase were partially altered to sericite, while biotite was altered to chlorite

(Figures 4.2d-4.2f). Silicic alteration contains abundant quartz crystals (Figures 4.2h-

4.2i). According to the result of XRD and petrography analyses, the alteration zone from previous research (Richardson, 2016) is consistent with our result for silicic zone

Chapter 4

Figure 4. 2 (a) quartz+molybdenite+pyrite vein host in granodiorite associated with phyllic alteration; (b), (c) sericitic alteration halos around a quartz+molybdenite +pyrite vein; (d) pyrite veinlet cut granodiorite associated with phyllic alteration; (e), (f) phyllic alteration shows K-feldspar and plagioclase replaced by sericite and biotite altered to chlorite; (g) silicified rock; (h) and (i) photomicrograph of silicic alteration showing quartz crystal. Abbreviation: qtz: quartz, K-fsp: K-feldspar, bt: biotite, chl: chlorite, ser: sericite, py: pyrite, mo: molybdenite. but it is a little bit different for phyllic alteration zone. Based on our result, inner phyllic and outer phyllic alteration by previous study (Richardson, 2016) are merged into a phyllic alteration that consists of mineral assemblage sericite±chlorite±smectite

±kaolinite (Table 4.1). Samples description and XRD results are demonstrated in

Appendix 1.

Chapter 4

4.2.2 Drill hole HD1

Generally, the shallow depths (~14 to 85m) of this drill hole are dominated by phyllic alteration hosted in volcaniclastic rocks (dacite composition), whereas deeper part from 85m to 155m of drill hole HD1 associated with potassic alteration hosted in quartz feldspar porphyries and andesite porphyries. The phyllic alteration assemblages

Figure 4. 3 Photographs (A-C) and photomicrographs (a-c) of phyllic alteration in drill hole HD1; (a) quartz+pyrite+chalcopyrite vein stockworks in dacite are heavily

Chapter 4

overprinted by sericite (depth 24m); (b) quartz+pyrite+chalcopyrite vein cut quartz feldspar porphyry associated with phyllic alteration (depth 62m); (c) quartz+ molybdenite+pyrite vein cute quartz feldspar porphyry associated with phyllic alteration (depth 74m); (d),(e),(f) sericite replaced plagioclase subordinated with groundmass of quartz, biotite altered to chlorite in phyllic alteration, (E) X-ray diffraction pattern of bulk rock and oriented samples (D1-62). Abbreviation: qtz: quartz, bt: biotite, py: pyrite, cpy: chalcopyrite, mo: molybdenite. are dominated by sericite±kaolinite±chlorite. The main vein assemblages associated with phyllic alteration include quartz+pyrite+chalcopyrite vein stockworks, quartz+ pyrite+chalcopyrite vein, pyrite+chalcopyrite veins and quartz+molybdenite±pyrite± chalcopyrite vein (Figure 4.3A-5C). Intense phyllic alteration is characterized by pervasive replacement of plagioclase by sericite and weak replacement of biotite by chlorite with dissemination of pyrite and chalcopyrite (Figure 4.3a-4.3c and Figure

4.3E). Summary of alteration mineral assemblages and type of alteration in the Halo prospect at surface are demonstrated in Table 4.1. Core description and XRD analysis show in Appendix 2.

Potassic alteration is characterized by a mineral assemblage of K- feldspar+sericite+biotite±chlorite. Veins or veinlets associated with potassic alteration are biotite veinlets, quartz-K-feldspar vein, magnetite veinlets, quartz+magnetite

+chalcopyrite vein, quartz+pyrite+chalcopyrite+magnetite vein, pyrite+chalcopyrite veinlet accompanied with dissemination of pyrite, chalcopyrite and magnetite.

Magnetite is mainly disseminated or occurs as hairline micro-veinlets (Figures 4.4a-

4.4i).

Chapter 4

Figure 4. 4 Potassic alteration in drill hole HD1; (a) quartz-K-feldspar veinlet cutting quartz feldspar porphyry showing potassic alteration (depth 95m);(b) quartz feldspar porphyry consisting of pervasive pink K-feldspar and patches fine-grained hydrothermal biotite (depth 111m), (c) magnetite stockworks and quartz vein with pink K-feldspar halos host in andesite porphyry (depth 126m); (d) quartz+magnetite +chalcopyrite+pyrite vein cutting andesite showing K-feldspar altered around mineralized quartz veins (depth 107m); (e) magnetite veinlets, magnetite stockworks and quartz vein with K-feldspar halo in potassic alteration (depth 106m); (f) potassic alteration of quartz feldspar porphyry consisting of pervasive pink K-feldspar and patches of fine-grained hydrothermal biotite associated with quartz+pyrite +chalcopyrite+magnetite vein (depth 120m). Abbreviation: qtz: quartz, K-fsp: K- feldspar, bt: biotite, py: pyrite, cpy: chalcopyrite, mag: magnetite, mo: molybdenite.

K-feldspar in the veins is intergrown with quartz or occurs discontinuously at the vein margins (Figure 4.5a). Secondary biotite replaced hornblende while secondary

K-feldspar replaced plagioclase and groundmass and sericite replaced the core of plagioclase by potassic alteration (Figures 4.5B-4.5d). Biotite and chlorite occur as centerline of quartz vein while pyrite and chalcopyrite formed as clots in secondary

Chapter 4

biotite. Hydrothermal biotite and magnetite formed as patches in the quartz feldspar porphyry (Figures 4.5e, 4.5f). Secondary K-feldspar occurs on rim of plagioclase and in groundmass (Figure 4.5g). Hydrothermal biotite occurs as aggregates of fine grained flakes with quartz and magnetite (Figures 4.5h-6i).

Figure 4. 5 Photomicrograph showing potassic alteration in HD1; (a) K-feldspar in quartz vein and groundmass of K-feldspar with magnetite and quartz on the margin of vein; (b) hornblende euhedral crystal has been altered to secondary biotite subordinated with groundmass of plagioclase, K-feldspar and quartz; (c) secondary K- feldspar replace igneous plagioclase and secondary K-feldspar and quartz occur as groundmass; (d) K-feldspar and quartz occur as groundmass with dissemination of magnetite; (e),(f) hydrothermal biotite occur as patches with chalcopyrite and magnetite in potassic alteration; (g) secondary biotite completely replace plagioclase, secondary K-feldspar rims igneous plagioclase, fined grained of secondary biotite; (h) and (i) hydrothermal biotite occurs as aggregates of fine-grained flakes with quartz and magnetite. Abbreviation: qtz: quartz, pl: plagioclase, K-fsp: K-feldspar, bt: biotite, ser: sericite, zr: zircon, mag: magnetite, cpy: chalcopyrite.

Chapter 4

4.2.3 Drill hole HD2 Ten granodiorite porphyry samples from HAL17-002D (depths:187m, 218m,

220m, 248m, 273m, 294m, 327m 356m, 364m, and 380m) are dominated by weak potassic alteration, characterized by mineral assemblage of K-feldspar+biotite

+sericite±chlorite±anhydrite ±epidote (Table 4.2). The ore minerals are disseminated in rocks, in addition to quartz+molybedenite vein, quartz+chalcopyrite+pyrite

+magnetite+molybdenite vein, quartz+molybdenite+pyrite vein, and quartz+ chalcopyrite+pyrite vein and magnetite veinlet (Figures 4.6a-4.6h).

Figure 4. 6 Vein and veinlet associated with potassic alterations in hole HD2, (a) quartz+molybdenite vein cutting by later quartz+calcite vein consisting of pervasive pink K-feldspar and patches fine-grained hydrothermal biotite (depth 218m); (b) quartz+molybedenite vein cut granodiorite porphyry (depth 220); (c) potassic altered granodiorite porphyry with pink K-Feldspar and fine-grained patches hydrothermal biotite associated with quartz+chalcopyrite+pyrite+magnetite+molybdenitevein (248m) (d) quartz+pyrite+chalcopyrite+molybdenite vein cut by later pyrite+veinlet associated potassic alteration of granodiorite porphyry consisting of pink groundmass K-feldspar and fine-grained patches biotite (273m); (e) quartz+pyrite+chalcopyrite cut granodiorite porphyry (294m); (f) magnetite veinlet cutting granodiorite porphyry(depth 380m). Abbreviation: qtz: quartz, cpy: chalcopyrite, py: pyrite, mag: magnetite, mo: molybdenite.

Chapter 4

Fine-grained of K-feldspar rims igneous plagioclase, accompanied with cluster of hydrothermal biotite and groundmass on the margin of quartz vein (Figures 4.7a-

4.7b). Phenocrysts of biotite are altered chlorite and subordinated with groundmass of quartz whispered in potassic alteration (Figure 4.7c). Secondary K-feldspar rims igneous plagioclase phenocrysts, accompanied with fine-grained hydrothermal biotite.

Chapter 4

The core of plagioclase was altered to sericite. Anhydrite replaced hydrothermal biotite (Figure 4.7d-4.7f). Hornblende is almost completely altered into aggregates of shredded biotite, only the original shape of the hornblende phenocrysts remains and anhydrite replaced secondary biotite (Figures 4.7g-4.7i).

4.2.4 Drill hole HD3

Granodiorite and diorite in HD3 are mostly affected by phyllic alteration and prophylitic alteration. Phyllic alteration is characterized by a mineral assemblage of sericite+chlorite and the mineral assemblage of the propylitic alteration is typically epidote+chlorite+sericite. Mineralization associated with phyllic and propylitic alteration include quartz+molybdenite vein, quartz+magnetite+chalcopyrite+pyrite vein and disseminated pyrite and chalcopyrite in host rocks (Figure 4.8a-4.8c).

Figure 4. 8 (a) quartz+molybedenite vein cutting granodiorite associated with phyllic alteration (depth 87m); (b) quartz+magnetite+chalcopyrite+pyrite vein cutting diorite associated with propylitic alteration (depth 261m); (c) quartz+molybdenite vein cut by calcite veinlet host in diorite associated with prophylitic alteration (depth 284m); photomicrograph showing phyllic alteration and propylytic alteration:(d), (e)quartz, sericite, chlorite and pyrite in phyllic alteration; (f) epidote alteration of plagioclase and chlorite in prophylitic alteration. Abbreviation: qtz: quartz, K-fsp: K-feldspar, pl: plagioclase, bt: biotite, chl: chlorite, ser: sericite, epi: epidote, py: pyrite, cpy: chalcopyrite, mo: molybedenite, mag: magnetite.

Chapter 4

Pervasive sericite replaced plagioclase while chlorite replaced biotite with disseminated pyrite (Figure 4.8d-f). Propylitic alteration is characterized by intense epidote alteration of plagioclase, with weak chlorite alteration of biotite (Figures 4.8g-

4.8i).

4.2.5 Drill hole HD4

Five samples from HD4 are characterized by propylitic and phyllic alteration hosted in hornblende diorite. Propylititc alteration is characterized by mineral assemblage of epidote+chlorite +sericite+calcite and phyllic alteration is characterized by mineral assemblage of sericite+chlorite. Mineralization consists of disseminated minor pyrite and trace chalcopyrite, pyrite veinlet, quartz+anhydrite+pyrite vein

(Figures 4.9a-4.9e).

Figure 4. 9 Propylititc and phyllic alteration in drill hole HD4(a) calcite+epidote veinlets and epidote alteration in hornblende diorite (depth 224m); b) pyrite veinlet with epidote alteration halo in hornblende diorite (depth 262m); (c) quartz+anhydrite+pyrite vein cut hornblende diorite (depth 277m); (d) quartz+anhydrite+pyrite cut hornblende diorite associated with phyllic alteration (depth 289m). Abbreviation: qtz: quartz, epi: epidote, anh: anhydrite, py: pyrite.

Propylitic alteration consist mainly of epidote alteration of plagioclase with lesser chlorite alteration biotite (Figure 4.10a-4.10f). Phyllic alteration occurs as selective replacement of plagioclase to sericite, while biotite and hornblende altered to

Chapter 4

chlorite (Fig. 12g-12i). Alteration mineral assemblages and type of alteration in drill holes of the Halo prospect are demonstrated in Table 4.2.

Table 4. 1 Alteration mineral assemblages (petrography and XRD analysis) and type of alteration in the Halo prospect at surface.

Type of Sample ID Name of rock Mineral assemblages No. Alteration 1 ALT01 Oxidized rock sericite Phyllic 2 ALT02 Diorite sericite+chlorite Phyllic 3 ALT03 Diorite sericite+chlorite Phyllic 4 ALT04 Granodiorite sericite+chlorite Phyllic 5 ALT05 Diorite sericite+chlorite Phyllic 6 ALT06 Silicified rock sericite+chlorite Phyllic 7 ALT07 Diorite sericite+chlorite Phyllic 8 ALT08 Granodiorite sericite+chlorite Phyllic 9 ALT09 Granodiorite sericite+chlorite Phyllic

Chapter 4

Table 4.1 (Cont.)

10 ALT10 Diorite sericite+chlorite+smectite Phyllic 11 ALT11 Granodiorite sericite+chlorite Phyllic 12 ALT12 Granodiorite sericite+chlorite+smectite Phyllic 13 ALT13 Granodiorite sericite+chlorite Phyllic 14 ALT14 Granodiorite sericite+chlorite Phyllic 15 ALT15 Granodiorite sericite+chlorite Phyllic 16 ALT16 Granodiorite sericite+chlorite Phyllic 17 ALT17 Granodiorite sericite+chlorite Phyllic 18 ALT18 Granodiorite sericite+chlorite Phyllic 19 ALT19 Andesite sericite+chlorite Phyllic 20 ALT20 Granodiorite sericite+chlorite Phyllic 21 ALT21 Granodiorite sericite+chlorite Phyllic 22 ALT22 Silicified rock quartz Silicic 23 ALT23 Granodiorite sericite+chlorite Phyllic 24 ALT24 Silicified rock quartz Silicic 25 ALT25 Silicified rock quartz Silicic 26 ALT26 Silicified rock quartz+sericite Silicic 27 ALT27 Silicified rock quartz Silicic 28 ALT28 Silicified rock quartz Silicic

Table 4. 2 Alteration mineral assemblages (petrography and XRD analysis) and type of alteration in drill holes of Halo prospect.

No Rock Types Sample Mineral assemblages Type of Name Alteration 1 Clay D1-1.40 sericite +kaolinite Phyllic 2 Altered rock D1-4.70 sericite +kaolinite Phyllic 3 Altered rock D1-7.70 sericite +kaolinite Phyllic 4 DC1 D1-12.5 sericite+kaolinite+chlorite Phyllic 5 DC1 D1-14.15 sericite+kaolinite+chlorite Phyllic 6 DC1 D1-17 sericite+kaolinite+chlorite Phyllic 7 DC1 D1-28 sericite+kaolinite+chlorite Phyllic 8 DC1 D1-43.45 sericite+kaolinite+chlorite Phyllic 9 QFP1 D1-50.15 sericite+kaolinite+chlorite Phyllic 10 QFP1 D1-59.40 sericite+kaolinite+chlorite Phyllic 11 QFP1 D1-62.0 sericite+kaolinite+chlorite Phyllic 12 QFP1 D1-67.40 sericite+kaolinite Phyllic 13 QFP1 D1-70-30 sericite+kaolinite+chlorite Phyllic 14 QFP1 D1-73-3 sericite+kaolinite+chlorite Phyllic 15 QFP1 D1-80-30 sericite+chlorite Phyllic 16 QFP1 D1-89 K-feldspar+sericite+biotite+chlorite Potassic

Chapter 4

Table 4.2 (Cont.) 17 QFP1 D1-90.80 K-feldspar+sericite+biotite+chlorite Potassic 18 QFP1 D1-97.75 K-feldspar+sericite+biotite+chlorite Potassic 19 ADNP1 D1-100.40 K-feldspar+sericite+biotite+chlorite Potassic 20 QFP1 D1-104 K-feldspar+ericite+biotite+chlorite Potassic 21 ANP1 D1-107 K-feldspa+sericite+biotite+chlorite Potassic 22 QFP1 d1-111 K-feldspa+sericite+biotite+chlorite Potassic 23 QFP1 D1-120.5 K-feldspar+ericite+biotite+chlorite Potassic 24 QFP1 D1-121.2 K-feldspar+ericite+biotite+chlorite Potassic 25 ADNP1 D1-126.70 K-feldspar+ericite+biotite+chlorite Potassic 26 DI2 D2-17.75 sericite+chlorite Phyllic 27 DI2 D2-65 sericite+chlorite Phyllic 28 GRDP2 D2-187 K-eldspar+biotite+sericite+chlorite Potassic +anhydrite 29 GRDP2 D2-218 K-feldspar+biotite+sericite+chlorite Potassic +anhydrite 30 GRDP2 D2-248 K-feldspar+sericite+biotite+chlorite Potassic 31 GRDP2 D2-273 Kfeldspar+biotite+sericite+chlorite Potassic +anhydrite 32 GRDP2 D2-294 K-feldspar+sericite+biotite+chlorite Potassic +andhyrite+epidote 33 GRDP2 D2-313 K-feldspar+biotite+sericite+ Potassic chlorite+anhydrite 34 GRDP2 D2-356 K-feldspar+sericite+biotite+chlorite Potassic +andhyrite+epidote 35 GRDP2 D2-364 K-feldspar+sericite+biotite+chlorite +andhyrite+epidote Potassic 36 GRDP2 D2-380 K-feldspar+sericite+biotite Potassic +chlorite+andhyrite 37 GRD3 D3-78 sericite+chlorite Phyllic 38 GRD3 D3-94 sericite+chlorite Phyllic 39 GRD3 D3-218 epidote+sericite+chlorite Propylitic 40 DI3 D3-259 epidote+sericite+chlorite Propylitic 41 DI3 D3-261 epidote+sericite+chlorite Propylitic 42 DI3 D3262 epidote+sericite+chlorite Propylitic 43 DI3 D3-284 epidote+sericite+chlorite Propylitic 44 HGRD4 D4-37 epidote+sericite+chlorite Propylitic 45 HGRD4 D4-39 epidote+sericite+chlorite Propylitic 46 HGRD4 D4-40 epidote+sericite+chlorite Propylitic 47 HGRD4 D4-87 epidote+sericite+chlorite Propylitic 48 HDI3 D4-223 epidote+sericite+chlorite Propylitic 49 HDI3 D4-277 epidote+chlorite+sericite+anhydrite Propylitic 50 HDI3 D4-300 epidote+chlorite+sericite Propylitic 51 HDI3 D4-320 epidote+chlorite+sericite Propylitic Abbreviations: DC1, QFP1 and ANP1: dacite, quartz feldspar porphyry, andesite porphyry, respectively in drill hole HD1, DI2 and GRDP2: diorite and granodiorite porphyry in HD2, DI3 and GRD3: diorite and granodiorite in HD3, respectively, HDI4 and HGRD4: hornblende diorite and hornblende granodiorite in drill hole HD4.

Chapter 4

4.3 Mineralization and Vein System Mineralogy

A variety of mineralization styles are disseminated sulfides, veinlets, and stockworks veins. Ore minerals are dominated by pyrite, chalcopyrite, and molybdenite, with minor magnetite, sphalerite, hematite, pyrrhotite, and galena.

Gangue minerals include quartz, plagioclase, K-feldspar, sericite, chlorite, biotite, with minor hornblende, epidote, anhydrite, and calcite. Anhedral chalcopyrite, pyrite, and galena occur in stockwork quartz veinlets, and are disseminated associated with phyllic alteration (Figure 4.11a-4.11c). Chalcopyrite, pyrite, magnetite, and hematite were formed in quartz vein and as dissemination in rock associated with potassic alteration

(Figure 4.11d-4.11f). Molybdenite mainly occurs in quartz vein and the margin of quartz vein and pyrite, chalcopyrite and pyrrhotite are disseminated associated with phyllic alteration (Figure4.11.g-4.11i).

Chapter 4

Figure 4. 11 Photomicrograph of (a) anhedral of chalcopyrite on the margin of quartz stockwork veinlets associated with phyllic alteration (24m); (b) disseminated of anhedral chalcopyrite in feldspar porphyry in phyllic alteration (D1-28); c) galena and chalcopyrite in quartz+galena+sphalerite+pyrite+chalcopyrite veinlets; d) subhedral- anhedral of chalcopyrite and pyrite in quartz+magnetite+pyrite+chalcopyrite associated with potassic alteration (D1-95); (e) and (f) chalcopyrite, magnetite, hematite and covellite disseminated throughout the rocks and veinlet are hostedin andesite dyke (D1-126) ; (g) and (h) blade-scaly molybdenite occurs as veinlet associated with phyllic alteration (D2-364 and S8.1); i) chalcopyrite inclusion in pyrite and pyrrhotite associated with phyllic alteration (HL06, outcrop sample). Abbreviations: cpy: chalcopyrite, py: pyrite, ga: galena, mag: magnetie, hm: hematite, mo: molybdenite, po: pyrrhotite and cv: covellite, D1: drill hole HD1, D2: drill hole HD2, S8.1 and HL06: outcrop sample.

Based on the structural, textural, crosscutting relationships, mineralogy and related hydrothermal alteration types, four stages of veins can be distinguished:

Stage I: quartz+magnetite±chalcopyrite±pyrite±molybdenite±pyrrhotite vein

(also call as A vein). These veins mainly occur in quartz feldspar porphyry, granodiorite porphyry and andesite porphyry associated potassic alteration but also occurs locally in diorite associated propylitic alteration (1 sample). These veins sometime accompanied by alteration halos of K-feldspar and biotite veinlets. Sericite, chlorite with minor epidote and anhydrite are found in rocks that associated with this veins (Table 4.3). In this stage, secondary K-feldspar completely replaces and rims plagioclase phenocrysts and occurs as groundmass. Hydrothermal biotite and magnetite occurs as pathches associated with pyrite.

Chapter 4

Table 4. 3 Mineral paragenesis for the Halo porphyry copper-molybdenum prospect

Stage Hydrothermal period Supergene period Mineral Stage I Stage II Stage III Stage IV Quartz ++++ ++++ ++++ +++ K-feldspar ++++ +++ Biotite ++ ++ Sericite ++ +++ +++ Anhydrite + +++ Gypsum +++ Chlorite ++ ++ ++ ++ Epidote + + +++ Kaolinite + + Calcite +++ Pyrite +++ ++ +++ +++ Pyrrhotite + Molybdenite ++ ++++ Chalcopyrite +++ + + Covellite + Sphalerite ++ Galena ++ Magnetite ++++ Hematite + + Goethite +

++++: Major, +++: Common, ++: Minor, +: Trace

Chalcopyrite formed within quartz vein and magnetite formed on the margin quartz vein in quartz feldspar porphyry (Stage I, Figure 4.12a, 4.13a) associated with potassic alteration. Chalcopyrite, magnetite, hematite, covellite, pyrite occurs on the margin of quartz vein in andesite porphyry associated with potassic alteration (Figure 4.12b,

Chapter 4

4.13b). Magnetite intergrowth coexisting with pyrite and chalcopyrite and magnetite inclusion in pyrite and chalcopyrite occur in potassic alteration, hosted in granodiorite porphyry (Stage I, Figure 4.12c, and 4.13c).

Stage II: quartz+molybdenite±chalcopyrite±pyrite vein (also call as B vein).

This stage is the main molybdenum mineralizing stage characterized molybdenite at margins and centerlines of quartz veins with sericite alteration halos and minor of pyrite and chalcopyrite, which are associated with phyllic and potassic alteration.

Pyrrohotite are disseminated in the rocks that associated with stage II vein. Phyllic alteration is characterized by the development of sericite alteration selvages along the margins of ore-bearing veins and selective replacement of feldspar phenocryst by sericite. These veins are often cut by later stage veins (Figure 4.13c). Molybdenite occurs within quartz vein in granodiorite porphyry and granodiorite (Stage II, Figure

4.12d, 4.13d-4.13e) followed by later stage quartz+pyrite+chalcopyrite+sphalerite

+galena (stage III, Figure 4.12e, 4.13f), associated with phyllic alteration.

Stage III: quartz+pyrite±chalcopyrite±sphalerite±galena vein or veinlet. The quartz+pyrite veinlets often cut the early vein. The sulfides are mainly pyrite, with minor sphalerite, galena and trace of chalcopyrite. This stage also formed in stockwork and vein ores. This veins mainly associated with phyllic alteration that consist of sericite with minor of chlorite and trace kaolinite.

Stage IV: quartz±calcite±anhydrite±gypsum±pyrite±chalcopyrite vein or veinlet

(Figure 4.13g). These veins are found mainly in propylitic alteration, but also occur locally in phyllic and potassic alteration. In this stage vein occurred within the stockwork and vein ores. Pyrite occurs within anhydrite vein of hornblende diorite

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associated with propylitic alteration (stage IV, Figure 4.12f; 4.13g).

Quartz+pyrite+chalcopyrite veinlet cut Stage I vein and Stage II vein, associated with potassic alteration and phyllic alteration, while quartz+anhydrite+pyrite vein associated with propylitic alteration.

Table 4. 4 Mineralization related to alteration

Chalcopyrite and molybdenite were mostly accompanied with phyllic and potassic alteration (Table 4.4). The main ore mineral of copper is chalcopyrite which is disseminated in host rock, stockworks vein and veins. These veins mainly consist of quartz+magnetite+chalcopyrite+pyrite±molybdenite vein, quartz+molybdenite+ chalcopyrite±pyrite vein, quartz+pyrite+chalcopyrite vein, and quartz+pyrite

+sphalerite+galena+chalcopyrite vein (Figure 4.13a-4.13c). The main molybdenum mineral in the deposit is molybdenite, which occurs as center-line filling of veins and at margin of quartz+molybdenite±chalcopyrite±pyrite vein (Figure 4.13d-4.13f).

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Figure 4. 13 (a), (b), (c) Stage I vein associated with potassic alteration d) Stage II vein associated with phyllic alteration; (e) Stage II and III vein associated with phyllic alteration; (f) Stage III quartz+molybdenite+pyrite+chalcopyrite vein cut by Stage IV gypsum veinlet; (g) Stage IV anhydrite+pyrite+chalcopyrite cutting diorite, with epidote and chlorite alteration halo; qtz: quartz, mag: magnetite, cpy:chalcopyrite, py: pyrite, mo: molybdenite, sp: sphalerite, ga: galena, anh: anhydrite, gym: gypsum.

Copper mineralization at Halo is associated with potassic and phyllic alteration.

High copper concentration is hosted in dacite, quartz feldspar porphyry and porphyritic granodiorite associated with phyllic and potassic alteration. High concentration of copper (7048ppm) is associated with stockwork veinlets and disseminated at the shallow depth approximately 10-28m of the drill hole HD1 (Figure 4.14b). The copper concentration associated with potassic alteration in the quartz feldspar porphyry and andesite porphyry is around 150 to 2670 ppm in the drill hole HD1 (disseminated and veins, stockworks veinlets, Figure 4.14, Table 4.4 and 4.5). Copper concentration associated with potassic alteration in the granodiorite porphyry is around 250-877ppm where copper minerals occur as veins and dissemination (HD2, Figure 4.14c Table 4.4 and 4.5). The copper mineralization in the dacite associated with phyllic alteration is higher than diorite and granodiorite associated with phyllic alteration in the drill hole

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HD2, HD3, HD4 and surface. Copper concentration in surface is high concentration up 1662 ppm hosed in oxidized rock while the low copper concentration range from 8 to 545ppm (disseminated in host rocks) and 35 to 823ppm (vein with rock) (Figure

4.14a).

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Molybdenum mineralization at Halo mainly occurs as veins hosted in the granodiorite porphyry and quartz feldspar porphyry that associated with phyllic and potassic alteration (Tables 3.4-3.5). Higher grades of molybdenum (6537ppm) occurs locally within the quartz+molybdenite veins (Figure 4.14a, Tables 4.5 and 4.6).

Molybdenum-bearing quartz veins occurs within the zone of phyllic alteration with weak potassic alteration. The ore minerals are mainly molybdenite and pyrite, and gangue minerals are quartz and sericite with minor amounts of chlorite and calcite.

The most quartz+molybdenite veins are hosted in the drill hole HD3.

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Chapter 4 Table 4. 5 summary of ore minerals assemblage and alteration in drill hole, +++: Major, ++: Common, +: Minor, -: None, n.d: Not determined

Cu Mo Sample ID Rock vein Alteration cpy cv mo py po mag hm sp ga ppm ppm D1-1 clay Reddish orange clay Argillic No data 329 497

D1-24 DC1 qtz+py+cpy vein Phyllic +++ - - ++ - - - + - 4336 n.d

D1-28 DC1 qtz+py+cpy vein ,qtz stockwork Phyllic +++ - - ++ - - - + - 7048 150

D1-53.2 QFP1 qtz+ga+sp+py+cpy vein Phyllic ++ - - +++ + - - + + 867 n.d

D1-65 QFP1 qtz+mo+py vein Phyllic ++ - +++ ++ - - - - - 985 3808

D1-71 QFP1 qtz+py+cpy+ga vein Phyllic ++ - - +++ - - - - + No data

D1-74 QFP1 qtz+mo+py vein Phyllic + - ++ +++ - - - - - 276 1003

D1-89 QFP1 qtz+mag+cpy+py vein and stockwork Potassic +++ - - ++ - ++ - - - 2432 nd

D1-95 QFP1 qtz+mag+cpy+py vein Potassic +++ - +++ - ++ + - 696 n.d

D1-107 ANP1 qtz+mag+cpy+py vein Potassic ++ + - ++ - +++ - - - 2670 n.d

D1-111 QFP1 bt veinlets with quartz vein stockwork Potassic 1274 n.d

D1-120.50 QFP1 qtz+mag+cpy+py+bt vein Potassic +++ + - +++ + ++ - - - 1869 181

D1-121 QFP1 qtz+mag+cpy+py vein Potassic ++ - - ++ - +++ - - - 511 185

D1-126 ANP1 qtz+mag+cpy+py vein Potassic +++ + - ++ + +++ +++ - - 371 n.d

D2-218 GRDP2 qtz+mo vein Potassic ++ - ++ ++ - - - - - 408 532

D2-220 GRDP2 qtz+mo vein Potassic + - ++ ++ - - - - - 223 655

D2-248 GRDP2 qtz+mag+cpy+py+mo vein Potassic +++ - ++ +++ - ++ - - - 845 796

D2-248 GRDP2 Host rock Potassic ++ - - ++ - - - - - 558 n.d

D2-294 GRDP2 Host rock Potassic +++ - - ++ - ++ - - - 758 n.d

D2-313 GRDP2 Host rock Potassic ++ - - +++ - + - - - 481 n.d

D2-356 GRDP2 qtz+cpy+py+mo veinlet Potassic +++ - + ++ - - - - - 877 33

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Chapter 4 D2-364 GRDP2 qtz+mo veinlet Potassic + - +++ ++ - - - - - 131 5297

D2-380 GRDP2 mag-veinlet Potassic ++ - - ++ - ++ - - - 802 38

D3-78 GRD3 qtz+mo vein Phyllic + - +++ + - - - - - 74 1945

D3-94 GRD3 qtz+mo vein cut by qtz+py+sp vein Phyllic + - +++ +++ - - - + - 96 1721

D3-189.7 DI3 qtz+mo+py vein cut by gypsum vein Propylitic + - +++ ++ - - - - - 32 1679

D3-261 DI3 qtz+mag+cpy+py cutting cal veinlet with epi Propylitic +++ - - + - +++ - - - No data

D3-284 DI3 qtz+mo+py vein cut cal-vein and epi-py veinlet Propylitic + - ++ ++ - - - - - n.d 1144

D4-227 HDI4 anh+qtz+py vein Prophylitic + - - +++ - - - - - n.d n.d

D4-320 HDI4 qtz+cal vein Prophylitic + - - + - - - - - No data Abbreviation: qtz: quartz, cpy: chalcopyrite, py: pyrite, cv: covellite, po: pyrrhotite, sp: sphalerite, goe: goethite, epi: epidote, cal: calcite, anh: anhydrite, DC1, ANP1, and QFP1: dacite, andesite porphyry and quartz feldspar porphyry, respectively, in drill hole HD1; GRD2: granodiorite porphyry in drill hole HD2; DI3and GRD3: diorite and granodiorite, respectively, in drill hole HD3; HDI4: hornblende diorite in drill hole HD4

Table 4. 6 summary of ore minerals assemblage and alteration in drill hole, +++: Major, ++: Common, +: Minor, - : None, n.d: Not determined

Cu Mo Sample ID Rock vein Alteration cpy cv mo py po goe sp ga hm ppm ppm S8.1 Granodiorite qtz+mo+py vein Phyllic alteration + + +++ + - - - - - 141 6537 S9.1 Granodiorite qtz+py+sp+cpy vein Phyllic alteration + - - +++ - - + - - 325 n.d Hl17A Diorite qtz+py+cpy vein Phyllic alteration + - - +++ - +++ - - - 35 533 Hl17F Diorite qtz+py vein Phyllic alteration + + - +++ - - - - - 823 353 ALT11 Diorite Host rock Phyllic alteration ++ - - +++ + - - - - 160 n.d ALT18 Granodiorite Host rock Phyllic alteration ++ + - +++ + - - - - 413 n.d ALT20 Granodiorite Host rock Phyllic alteration ++ + - +++ + - - - - 60 223 ALT21 Granodiorite Host rock Phyllic alteration ++ + - +++ + - - - - 38 n.d ALT26 Silicified Rock qtz vein Silicic alteration + + - + - - - - + No data No data ALT28 Silicified Rock qtz+py vein Silicic alteration + + - ++++ - - - + - No data No data Abbreviation: qtz: quartz, cpy: chalcopyrite, py: pyrite, cv: covellite, po: pyrrhotite, sp: sphalerite, goe: goethite, epi: epidote, 107

Chapter 4

4.4 Discussion and Conclusions

Rock textures, types of veins, patterns of alteration and mineral assemblages at

Halo similar to theory porphyry copper-molybdenum deposit from many parts of the world (e.g., Lowell and Guilbert, 1970), in terms of considering the porphyritic texture of rock, an early potassic alteration, late phyllic alteration and propylitic alteration.

HD1 and HD2 consist of potassic alteration and phyllic alteration, while HD3 and HD4 consisting of phyllic alteration and propylitic alteration. The copper concentration of HD1 range from 106 to 7048 ppm with molybdenite from 41 to 3308 ppm (Depth: 1 to 140m). The concentration of copper and molybdenum of HD2 range from 205 to 877 ppm and 33 to 5297 ppm, respectively, at depth from 8.5 to 364m

(Figure 4.15c). The high grade of copper ore occurs as stockwork quartz veinlets enveloped by phyllic alteration (sallow level), which overprinted on potassic alteration

(HD1). The high grade of molybdenum ore occurs as veins in granodiorite, and granodiorite associated with phyllic and potassic alteration. According to present of potassic and phyllic alteration associated mineralization style such as stockworks veinlets, magnetite veinlets, quartz+magnetite+chalcopyrite veins, quartz+pyrite

+chalcopyrite+magnetite veins, quartz+pyrite+chalcopyrite+molybdenite vein, quartz+molybedenite veins, quartz+chalcopyrite+pyrite+magnetite+molybdenite vein, quartz+molybdenite+pyrite vein, quartz+chalcopyrite +pyrite vein, hosted in the quartz feldspar porphyry, andesite porphyry and granodiorite porphyry with high grad of copper up to 7048ppm and molybdenum up to 5297 ppm in the drill hole number

HD1and HD2, thus the drill hole HD1 and HD2 are the most hosts of mineralization that connected to the mineralized porphyry system.

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The mineralization at Halo prospect occurred mainly in the quartz feldspar porphyry and granodiorite porphyry. The stockwork, vein type mineralization and dissemination ores in rocks are recognized in the Halo deposit.

The Halo copper-molybdenum deposit shows similar geological features and alteration zoning outward from the major orebody, alteration zones shift from potassic

(K-feldspar+biotite+sericite+chlorite±anhydrite±epidote) to phyllic (sericite±chlorite

±kaolinite±smectite), propylitic (epidote+chlorite+sericite+calcite), and silicic alteration. Copper mineralization was accompanied with both potassic and phyllic alteration. The main ore minerals are pyrite, chalcopyrite, and molybdenite, which are mostly associated which potassic and phyllic alteration. Chalcopyrite is the most important economic ore mineral.

Based on crosscutting relationships and mineralization of veins, the ore-forming process is divided into four stages such as: Stage I quartz+magnetite±molybdenite

±chalcopyrite±pyrite±pyrrhotite vein; Stage II quartz+molybdenite±chalcopyrite

±pyrite vein; Stage III quartz+pyrite+chalcopyrite±sphalerite±galena vein; and Stage

IV quartz±calcite±anhydrite±gypsum ± pyrite vein or veinlet.

References

Lowell, J.D. and Guilbert, J.M. (1970) Lateral and vertical alteration-mineralization

zoning in porphyry ore deposits. Economic Geology, 65, 373−408.

Richardson, C. T., Craig, J. R., Adrian, M. and Kurtis, D. (2016) Controls on

Polymetallic Vein Deposits and Porphyry Deposits in the Phum Syarung-Dok

Yong Fault Corridor, Ratanakiri Province, Cambodia, Unpublished Poster, Society

of Economic Geologists, 2016.

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Chapter 5: Fluid Inclusion Microthermometry and Sulfur Isotopes

5.1 Introduction

This chapter presents the fluid inclusion study in quartz with different stages to elucidate ore forming fluid and sulfur isotope analysis in order to understand about source of mineralized fluid at the Halo porphyry copper-molybdenum prospect.

5.2 Fluid Inclusion Petrography

Fluid inclusion was studied on the basis of petrography and microthermometry to constrain the pressure, temperature, and salinity of fluids related to quartz vein formation, alteration and metal assemblage. Fluid inclusions were identified as either primary or secondary in origin based on the criteria of Roedder (1984) and Bondar et al. (1985). The fluid inclusions identified as primary were measured in this study. Fluid inclusions are abundant in quartz of all vein types in different alteration zones in Halo, and ranging from 1 to 30µm in diameter. The major types of fluid inclusion are recognized in the analyzed quartz veinlets on the basis of phase content at room temperature. Based on the phase content at room temperature, the observed inclusions are mainly categorized into six types as follows (Table 5.1).

Type I: mono phase vapor; (V). These inclusions (3 to 10µm in diameter) are rounded isometric or elliptic in shape (Figure 5.1a, 5.1b). They consist only of vapor.

Type I inclusions occur in quartz vein (Stage VI vein) associated with trace amount of

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pyrite, chalcopyrite, hematite, magnetite and covellite of silicic alteration and quartz+molybdenite+pyrite vein (Stage II vein) associated with phyllic alteration.

Type II: liquid-rich (liquid+vapor). These inclusions (5 to 30µmin diameter) are in the form of oval, irregular, negative crystal and elliptical in shape (Figure 5.1c and

5.1d). They consist of a liquid and a < 50% vapor, and H2O is the major component.

They are the most abundant in various stage veins and alteration zones.

Type III: vapor-rich (vapor+liquid). These inclusions (5 to 15µmin diameter) are oval, negative crystal, rounded and irregular in shape (Figure 5.1e). They consist of a liquid and a>50% vapor. They occur in cluster with type I, II and VI in quartz+magnetite+pyrite+chalcopyrite vein (Stage I vein); quartz+molybdenite+pyrite vein (Stage II vein); quartz+pyrite+chalcopyrite+sphalerite+galena vein (Stage III vein) and; and quartz vein (Stage IV vein) associated with potassic, phyllic and silicic alteration, respectively.

Type IV: anhydrite-bearing liquid+vapor+opaque fluid inclusions. They contain a vapor bubble, a brine, anhydrite and opaque minerals. These inclusions (8 to 22µmin diameter) are in the form of rounded, elongated and irregular in shape, with vapor occupying 10 to 25vol% (Fig. 5.1f and 5.1g). They occur only quartz vein (Stage IV vein) associated with silicic alteration.

Type V: three phase liquid+vapor+opaque mineral. They contain a vapor bubble, a brine and/or hematite (rounded in shape), and/or chalcopyrite (variously rounded, triangular, diamond in shape) and/or opaque minerals (unknown mineral). These inclusions (6 to 20µmin diameter) are oval and irregular in shape, with a vapor occupying 10 to 35 vol% (Fig 5.1h and 5.1i). They occur in all quartz veins, but are

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absent in the quartz+pyrite+chalcopyrite+sphalerite+galena vein (Stage III vein, D1-

53) associated with phyllic alteration.

Type VI: halite-bearing liquid+vapor+opaque mineral fluid inclusions. They contain a vapor bubble, a brine liquid, a transparent cubic daughter crystal identified as halite, and/or one or more minute blebs of opaque mineral and /or reddish rounded

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hematite and/or chalcopyrite (rounded and triangular in shape) being the commonest daughter mineral similar to other porphyry copper deposits (Ulrich et al., 2002, Ulrich et al., 1999). The inclusions vary from 8 to 20µm in size and have rectangular, elongated and irregular in shape, with a vapor phase occupying 10-22 vol% (Figure

5.1j-5.1l).

Table 5. 1 Summary of fluid inclusion petrography

Measured Vol % Size Sample ID Vein Types Alteration Types number of vapor µm D1-120.0 qtz+mag+py+cpy vein Potassic 15 Type II 10-40 5-10 120.0m Stage I vein 5 Type III 55-60 8-10 7 Type V 10-20 6-10 10 Type VI 10-20 8-13 S8.1 qtz+mo vein Phyllic 21 Type II 8-30 6-20 Stage II Vein 4 Type III 60-95 6-9 5 Type V 10-30 8-12 S9-1 qtz+py+cpy+sp+ga vein Phyllic 33 Type II 12-45 5-20 Stage III Vein 2 Type III 55-80 5-11 1 Type V 15 12 D2-53.0 qtz+py+cpy+sp+ga vein Phyllic 27 Type II 8-50 5-12 53.0m Stage III Vein Hal17.A qtz+py+cpy vein Phyllic 15 Type II 15-50 5-12 Stage III Vein S9-3 qtz vein Silicic 34 Type II 15-45 8-30 Stage VI Vein 10 Type III 55-90 5-15 9 Type IV 10-25 8-20 16 Type V 5-35 6-20 15 Type VI 8-22 8-20 Abbreviation: qtz: quartz, py: pyrite, cpy: chalcopyrite, mag: magnetite, mo: molybdenite, goe: goethite. Type I: V, Type II: L+V, Type III: V+L, Type IV: L+V+A+op, Type V: L+V+op, Type VI; L+V+H±hm±cpy±op; L: liquid, V: vapor, anh: anhydrite, op: opaque mineral, H: halite,

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5.3 Microthermometry

5.3.1 Stage I Vein

Fluid inclusions in quartz+pyrite+chalcopyrite+magnetite vein (Stage I vein, depth 120m of HD1) associated with potassic alteration consist of liquid-rich (Type

II), vapor-rich (Type III), three phase vapor+liquid+opaque mineral (Type V) and halite-bearing inclusions (Type VI, liquid+vapor+halite±hematite±opaque mineral).

Ice melting temperature of vapor-rich inclusions was not obtained. The homogenization temperature (Th) and halite dissolution temperature (Td) of type VI range from 280 to 460oC and 425 to 485oC, respectively (Figure 5.2a). The liquid- vapor homogenization temperatures of halite-bearing fluid inclusions (Type VI) are lower than the halite dissolution temperatures. Thus, the salinities were calculated at the temperature of Th by equation reported by Sterner et al. (1988), assuming the hydrothermal solution was saturated with NaCl at the trapping temperature. Similar phenomena have been reported from several porphyry deposit such as the Mamut deposit in Malaysia (Nagano et al., 1977, Imai, 2000), the Dizon deposit in Philipines

(Imai, 2005) and Batu Hijau deposit in Indonesia (Imai and Ohno, 2005; Imai and

Nagai, 2009). The homogenization temperatures (Th) (from vapor+liquid to liquid) of type II, type V, and VI range from 203 to 309oC, 340 to 450oC and 280 to 460oC with salinity ranging from 1.2 to 8.4 wt. %, 10.0 to17.0wt. %, 36.0 to 55.0wt. % NaCl equiv, respectively. The homogenization temperatures (Th) of type III ranges from 215 to

364oC (Figure 5.2a and 5.2b).

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5.3.2 Stage II Vein Fluid inclusions in quartz+molybdenite+pyrite vein (Stage II vein, outcrop sample) associated with phyllic alteration consist of type II, type III, and type V inclusions. Ice melting temperature of type III and type V inclusions were not obtained.

The homogenization temperatures of type II inclusions range from 174 to 264oC with salinity from 4.0 to 14.0 wt. % NaCl equivalent. The homogenization temperatures of type III and type V inclusions range from 214 to 350oC and 205 to 280oC, respectively

(Figure 5.2c and 5.1d). The homogenization temperatures of type III and type V inclusions are 214oC and 280oC with corresponding salinity 0.8 wt. % and 9.8wt. %

NaCl equivalent, respectively. The entrapment of boiling fluid is supposed according to the coexistence of gas-rich inclusions and the wide range of homogenization temperatures. In the boiling system, the lower temperature represents the trapping temperature. Thus the formation temperature of the quartz vein associated with quartz vein associated with molybdenite and pyrite was about 174oC.

5.3.3 Stage III Vein

Fluid inclusions in quartz+pyrite+sphalerite+chalcopyrite vein (Stage III vein) associated with phyllic alteration (S9.1, outcrop sample) consist of type II, type III and type V inclusions. The homogenization temperatures of type II, and type III range from

201 to 357o C, and 327 to 357oC with a salinity of 0.53 to 14 wt. % and 3.60 to 5 wt. %

NaCl equivalent, respectively (Figure 5.2e and 5.2f). The homogenization temperatures of type V inclusion is 223oC and the salinity were not obtained. The entrapment of boiling fluid is supposed according to coexistence of gas-rich inclusion and the wide range of homogenization temperatures. In the boiling system, the lower temperature represents the trapping temperature. Thus the formation temperature of

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quartz vein associated with quartz vein associated with pyrite, sphalerite and chalcopyrite was about 201oC.

Fluid inclusions in quartz+galena+sphalerite+pyrite+chalcopyrite vein (Stage III vein, D1-53, depth 53m of HD1) associated with phyllic alteration are composed two phase liquid-vapor inclusions. Liquid-rich two phase inclusions are typically 4-12µm in length and 2-10 µm in width; vapor ~ 10-45 vol. %. The homogenization temperatures range from 174 to 306oC with final ice melting temperatures range from

-0.35oC to -2oC and corresponding salinity range from 0.35 to 2.0 wt. % NaCl equivalent (Figure 5.2g, 5.h). The wide ranges of homogenization temperatures as well as various liquid-vapor ratios of fluid inclusions in quartz+ganela

+sphalerite+chalcopyrite vein are supposed the entrapment of boiling fluid (Reodder,

1984, Bodnar et al., 1985, Imai, 2005).

Fluid inclusions of quartz+pyrite vein (Stage III Vein) associated with phyllic alteration (HAL17.A, outcrop sample, elevation, and 215m) consist two phase liquid- rich inclusions. The homogenization temperature ranges from 201 to 358oC with salinity ranging from of 1.5 to 14 wt. % NaCl equivalent (Figure 5.2i and 5.2j). The wide ranges of homogenization temperatures as well as various liquid-vapor ratios quartz+pyrite vein are supposed the entrapment of boiling fluid (Reodder, 1984,

Bodnar et al., 1985, Imai, 2005).

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5.3.4 Stage VI Vein Fluid inclusions of quartz vein with trace pyrite, chalcopyrite, hematite and covellite associated with silicic alteration (S9.3, outcrop sample) consist of six types of fluid inclusions (I-VI). Some vapor-rich fluids were not homogenized at temperature below 500oC. The homogenization temperatures (Th) (from vapor liquid to liquid) of type II, type IV, type V, and type VI fluid inclusions excluding the measurements are not homogenized below 500oC, range from 201 to 330oC, 200 to

370oC, 162 to 286oC, and 182 to 320oC with salinity ranging from 0.5 to 17.0 wt. %,

6.0 to16.0 wt. %, 7.0 to 21.0 wt. %, 31.0 to 44.0 wt. % NaCl equiv., respectively

(Figure 5.2k and 5.2l). The homogenization temperatures (Th) of type III ranges from

290 to 366oC and the salinity were not obtained.

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Figure 5. 2 Histograms of homogenization temperatures and salinity of fluid inclusions in different stage of quartz associated with different alteration: (a), (b) fluid inclusions in quartz+magnetite+pyrite+chalcopyrite vein (Stage I Vein) associated with potassic alteration (D1-120, depth 120m); (c), (d) fluid inclusion in quartz+molybdenite vein (Stage II) associated with phyllic alteration (S8.1, outcrop sample); (e), (f) fluid inclusion in quartz+pyrite+chalcopyrite+sphalerite+galena (Stage III) associated with phyllic alteration (S9.1,outcrop sample); (g), (h) fluid inclusions in quartz+pyrite+chalcopyrite+galena+sphalerite vein (Stage III Vein) associated with phyllic alteration (D1-53, depth 53m) ; i and j) fluid inclusion quartz+pyrite+chalcopyrite vein (Stage III vein) associated with phyllic alteration (HAL17A, outcrop sample); k and l) quartz vein (Stage IV Vein) associated with silicic alteration (S9.3, outcrop sample).

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5.4 Sulfur Isotopes Analysis

Sulfur isotope were measured on fifteen pyrite, three chalcopyrite, three molybdenite samples and three anhydrites. All samples were selected from quartz vein in drill holes and surface. The δ34S values of 21 sulfides from different types ores are concentrated in narrow range near +3‰, from -2.5‰ to +4.5‰ (Figure 5.3), with an average of +2.1‰. The δ34S values of fifteen pyrite sample range from -2.1‰ to

+4.3‰, with an average of +2.5‰ and the δ34S values of three chalcopyrite range from

-2.5‰ to +0.5‰, with an average of -0.8‰. The δ34S values of three molybdenite samples range from +0.5‰ to +4.5‰, with an average of +2.6‰. The δ34S values of three anhydrite samples range from +14.6‰ to +15.9‰, with an average 15.2‰. The determined δ34S values are summarized in Table 5.2, shown in histograms in Figure

5.3.

Figure 5. 3 Histogram of sulfur isotope compositions of sulfides and sulfate from the Halo Mo-Cu deposit. Abbreviation: py: pyrite, cpy: chalcopyrite, mo: molybdeneite

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Table 5. 2 Sulfur isotope compositions (δ34S‰) of sulfides from the Halo Porphyry Mo-Cu deposit

No Sample Location Vein types Stages veins Alteration Minerals δ34S (‰) 1 HAL06-1 Outcrop sample qtz+py vein cut silicified rock Stage III Silicic py +3 2 HAL06-2 Outcrop sample qtz+py vein silicified rock Stage III Silicic py +3.3 3 S8.1 Outcrop sample qtz+mo+py vein cut GRDO stage I Silicic Mo +0.5 4 S9.1 Outcrop sample qtz+py+sp+cpy vein cut GRGO stage III Silicic py +4.3 5 D1-74.0 #D1, 74.0m qtz+py+mo vein cut QFP1 stage II Phyllic py +3.3 6 D1-95.0 #D1, 95.0m qtz+mag+py+cpy vein cut QFP1 stage 1 potassic py +3.3 7 D1-120.0 #D1, 120.0m qtz+mag+cpy+py vein cut QFP1 stage I potassic py +2.5 8 D1-126.0 #D1, 126.0m qtz+mag+py+cpy vein cut QFP1 stage I potassic py +2.7 9 D1-126.0 #D1, 126.0m qtz+mag+py+cpy vein cut ANDP1 stage I potassic cpy +0.5 10 D2-234.1 #D2, 234.1m qtz+cpy cut GRDP2 stage IV - cpy -0.5 11 D2-234.1 #D2, 234.1m qtz+py cut GRDP2 stage IV - py +2.9 12 D2-248.0 #D2, 248.0m qtz+mag+py+cpy+mo vein cut GRDP2 stage I potassic py -2.1 13 D2-248.0 #D2, 248.0m qtz+mag+py+cpy vein cut GRDP2 stage I potassic cpy -2.5 14 D2-275.0 #D2, 275.0m qtz+py+ga vein stage IV - anh +15.1 15 D3-189.0 #D3, 189.0m qtz+py+mo vein cut GRD3 stage II Phyllic py +3 16 D3-189.0 #D3, 189.0m qtz+py+mo vein cut GRD3 stage II Phyllic Mo +2.8 17 D3-94.0 #D3, 189.0m qtz+py+sp+cpy vein cut GRD3 stage III Phyllic py +3.6 18 D3-94.0 #D3, 94.0m qtz+py+sp+cpy vein cut GRD3 stage III Phyllic py +3.1 19 D3-94.0 #D3, 94.0m qtz+mo vein cut GRD3 stage II Phyllic Mo +4.5 20 D4-277.0 #D4, 277.0m anhyrite+quartz+py cut HDI4 stage IV Propylitic py +2.8 21 D4-277.0 #D4, 277.0m anhyrite+quartz+py cut HDI4 stage IV Propylitic py +1.4 22 D4-277.0 #D4, 277.0m anhyrite+quartz+py cut HDI4 stage IV Propylitic anh +15.9 23 D4-307.0 #D4, 307.0m anhyrite+quartz+py cut HDI4 stage IV Propylitic py +1.7 24 D4-307.0 #D4, 307.0m anhyrite+quartz+py cut HDI4 stage IV anh +14.6 Abbreviations: #D1: HD1, #D2: HD2, #D3: HD3, #D4: HD4 (drill holes), number after D1, D2, D3 and D4: Depth; QFP1 and ANDP1: quartz feldspar porphyry and andesite porphyry, respectively, in HD1, GRDP2: granodiorite porphyry, GRD3: granodiorite in HDI4: hornblende diorite in HD4, cpy: chalcopyrite, py: pyrite, mo: molybdenite, anh: anhydrite

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5.5 Discussion

The occurrence of halite-bearing hypersaline fluid inclusions in quartz+magnetite+pyrite+chalcopyrite vein and quartz vein associated with potassic and silicic alteration, respectively. Similar phenomena have been reported from several porphyry deposit such as the Mamut deposit in Malaysia (Nagano et al., 1977, Imai,

2000), the Dizon deposit in Philipines (Imai, 2005) and Batu Hijau deposit in Indonesia

(Imai and Ohno, 2005; Imai and Nagai, 2009).

The liquid-vapor homogenization temperatures (Th) of type VI inclusions in quartz+magnetite+chalcopyrite+pyrite vein (Stage I vein) and quartz vein (Stage VI

Vein, S9.3, outcrop sample) are lower than the halite dissolution temperatures (Td).

Thus it suggests that there is the presence saturated of NaCl at the time of entrapment of the type VI fluid inclusions. Wide ranges of Th and Td of halite-bearing inclusions in quartz+magnetite+chalcopyrite+pyrite vein and quartz vein ranging from 280 to

460oC, 182 to 320oC and 425 to 485oC, 256 to >500oC, respectively, suggest heterogenous entrapment of inclusion fluids of gaseous vapor and hypersaline brine with variable ratios. Similar phenomena have been reported from several porphyry deposit such as Imai, 2005; Imai and Ohno, 2005; Imai and Nagai, 2009). Thus, the minimum Th of halite-bearing inclusions can be considered as the trapping temperature of quartz+magnetite+chalcopyrite+pyrite vein and quartz vein with the estimated salinity 31 wt. % NaCl equivalent and 37wt. % NaCl equivalent, respectively. The aqueous fluid immiscible region into hypersaline brine and dilute vapor encountered at 280oC and 182oC suggests the minimum pressure to be about 43 bars and 10 bars based on the liquid-vapor-halite three phase line (Figure 5.4) assuming the saturation of NaCl (Roedder and Bondar, 1980, 1997).

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Fluid inclusion in quartz+galena+sphalerite+pyrite+chalcopyrite vein (Stage III vein), quartz+pyrite+chalcopyrite vein (Stage III Vein), quartz+pyrite +chalcopyrite

+sphalerite+galena vein (Stage III Vein), quartz+molybdenite vein (Stage II Vein) associated with phyllic alteration are mostly dominated by liquid-rich inclusions. The estimated pressure of all vein associated with phyllic alteration are plotted along the boiling point curve of pure water as the inclusion fluid are presumed to be dilute aqueous fluid.

The liquid-rich two-phase fluid inclusion of quartz+pyrite+chalcopyrite

+sphalerite+galena vein, quartz+pyrite+chalcopyrite vein, quartz+pyrite+chalcopyrite

+galena+sphalerite vein, quartz+molybdenite vein homogenized into liquid phase at temperatures ranging widely from 174 to 306oC, 201 to 358oC,201 to 357oC and 174 to 264oCwith salinity range from 0.3 to 2.0wt. %, 1.5 to 14.0 wt. %, 0.5 to 14.0 wt.%,

4.0 to 14.0 wt.% NaCl equivalent, respectively (Figure 5.2). The trapping temperature of hydrothermal fluid are considered to be around 174oC, 201oC, 201oC, and 174oC since the entrapment of boiling hydrothermal solution is supposed. Thus the depth and temperature of about 13 bars and 174oC, 20 bars and 201oC, 20 bars and 201oC and

13bars and 174oC (Hass, 1984; Roedder and Bondar, 1980; Roedder, 1984, Imai,

2005) are estimated for the hydrothermal fluid precipitated quartz associated with galena, sphalerite, pyrite, chalcopyrite; quartz associated with pyrite, goethite, chalcopyrite; quartz associated with pyrite, sphalerite, chalcopyrite; and quartz associated with molybdenite, pyrite, respectively (Figure 5.4). Results of ﬂuid inclusion microthermometry on quartz veins including homogenization temperature, salinity and pressure are summarized in Table 5.3.

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Figure 5. 4 Relationship between homogenization temperature and pressure deduced from fluid inclusion microthermometry. The boiling point curve originating from the critical point of pure water (Sourirajan and Kennedy, 1962) and the liquid-vapor-halite three phase line (Roedder and Bodnar, 1980, 1997) are illustrated for reference. Symbols: solid diamond ( ): quartz+pyrite+chalcopyrite+magnetite vein stage I vein associated with potassic alteration (D1-120, 120m in HAL17-001D); white diamond ( ): quartz veinlet associated with silicic alteration (S9-3, surface sample near drill hole HAL17-003D); open rectangular ( ): quartz+galena+sphalerite+pyrite +chalcopyrite vein , stage III associated with phyllic alteration (#D1-53,53m in HAL17-001D), open circle ( ): quartz+pyrite+sphalerite+chalcopyrite vein (Stage III vein) associated with phyllic alteration, open triangular ( ): quartz+pyrite+goethite+chalcopyrite vein associated with phyllic alteration, ssolid circle ( ): quartz+molybdenite+pyrite vein, Stage II associated with phyllic alteration

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Table 5. 3 Summary of fluid inclusion microthermometry of the Halo deposit.

Salinity Measured Td of halite (°C) Pressure Depth Sample ID Vein Types Alteration Types Th (°C) (wt %) number (bar) (m) NaCl eq D1-120.0 qtz+mag+cpy+py vein Potassic 12 Type II 203-309 - 1.2-8.4 120m Stage I Vein 2 Type III 340-450 - - 7 Type V 215-364 - 10.0-17.0 10 Type VI 280-460 425-485 36.0-55.0 43 S8.1 qtz+mo+vein Phyllic 21 Type II 174-264 - 4.0-14.0 13 130 Stage II Vein 4 Type III 214-350 - - 5 Type V 205-280 - - S9-1 qtz+py+cpy+sp+ga vein Phyllic 33 Type II 201-357 - 0.5-14.0 20 200 Stage III Vein 2 Type III 327-357 - 3.6-5.0 1 Type V 223.7 - - D2-53.0 qtz+py+cpy+sp+ga vein Phyllic 27 Type II 174-306 - 0.3-2.0 13 130 53m Stage III Vein Hal17.A qtz+py+cpy vein Phyllic 15 Type II 201-358 - 1.5-14.0 20 200 Stage III Vein S9-3 qtz vein Silicic 34 Type II 201-330 - 0.5-17.0 Stage VI 10 Type III 290->366 - - 9 Type IV 200-370 - 6.0-16.0 16 Type V 162-286 - 7.0-21.0 15 Type VI 182-320 256 ->500 31.0-44.0 10 Abbreviation: Th: vapor-liquid homogenization temperature, Td: halite dissolution temperature, Tm: ice-melting temperature, qtz: quartz, py: pyrite, cpy: chalcopyrite, mag: magnetite, mo: molybdenite, goe: goethite. Type I: V, Type II: L+V, Type III: V+L, Type IV: L+V+A+op, Type V: L+V+S, Type VI; L+V+H±hm±cpy±op; L: liquid, V: vapor, A: anhydrite, S: opaque mineral, H: halite. Salinity estimated by fluid ice-melting temperature (Bondar &Vityk, 1994) and halite dissolution temperature (Sterner et al., 1988); salinity of two phase ; wt% NaCl=0.00+1.78Tm-0.0442Tm2+0.000557Tm3 and salinity of halite-bearing fluid inclusion wt% NaCl = 26.242 + ( 0.4928×Td ) + ( 1.42 × Td2 ) (0 .223 ×Td3 ) + ( 0.04129×Td4 ) ( 0.006295×Td 5 ) − (0 .001967×Td 6 )+ ( 0.00011112×Td7 ) ; Note: Td = (Td /100). For the inclusions having Th < Td, the salinities were calculated at the temperature of Td, assuming that the hydrothermal solution was saturated with NaCl at the trapping temperature

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Fluid inclusion in quartz+pyrite+chalcopyrite+magnetite vein (Stage I vein) and quartz vein (Unknown stage) associated with potassic and silicic alteration, respectively, consist of halite-bearing fluid inclusion, therefore the presence of high saline inclusions in the vein ore shows that the deposition of vein ore is near the mineralizing center of magmatic hydrothermal. Quartz vein associated with slilicic alteration contains type I-VI fluid inclusions. The type V and VI inclusion contains chalcopyrite as daughter mineral.

34 The δ SH2S of the ore-forming fluid is calculated about +0.6‰ in average value using the δ34S value of pyrite, pyrite, and molybdenite (Table 5.3), formation temperature of quartz+pyrite+chalcopyrite+magnetite vein, quartz+pyrite+sphalerite

+chalcopyrite, and quartz+molybdenite+pyrite vein from fluid inclusion study and

6 2 equation Δ(sulfide-H2S) = A(10 /T ) that A is equilibrium isotopic fractionation factor of

34 sulfur compounds with respect to H2S Ohmoto and Rye (1979). The δ SH2S values

34 coincide within the δ SH2S range for magmatic fluids (e. g., -3‰ to +3%) defined by

Ohmoto and Rye, 1979.

34 The range of δ Ssulfide+sulfate values from the Halo copper-molybdenum

34 34 porphyry deposits (δ Ssulfide from -2.5 to +4.5 ‰ and δ Ssulfate from +14.6 to +15.9 ‰) is similar to the range typical for porphyry copper deposits worldwide (Figure 5.5;

34 34 δ Ssulfide: -3 to +1 ‰; δ Ssulfate: +8 to +15 ‰; Field and Gustafson, 1976, Ohmoto and

Rye, 1979; Ohmoto and Goldhaber, 1997; Rye, 2005; Wilson et al., 2007). The near-

34 zero δ Ssulfide values for the Halo indicate a predominantly magmatic sulfur source

(e.g., Ohmoto and Rye, 1979; Field and Fifarek, 1985). Moreover, the δ34S values of sulfide from the Halo porphyry deposit is consistent with other porphyry deposits such as Butte porphyry copper-molybdenum, Dabu porphyry copper-molybdenum and

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Qulong porphyry copper-molybdenum deposits (Figure 5.5), all of which are closed to the primitive mantle range (+0.5‰; Chaussidon et al., 1989), indicated contribution from the mantle to the ore-forming fluids.

The δ34S values of anhydrite and pyrite vein associated propylitic alteration in drill hole HD4 at depth 277m and 307m are +15.9 ‰ and +1.4 ‰ and +14.6 ‰ and

+1.7 ‰, respectively. The difference of δ34S values between anhydrite and pyrite at depth 277m and 307m 14.5 ‰, and are 12.9 ‰, corresponding to 407.7°C and 450.5°C, assuming equilibrium in sulfur isotopic fractionation (Ohmoto and Goldhaber, 1997).

This seems too high considering the mode of occurrence of late stage vein associated with propylitic alteration, and may suggest isotopic disequilibrium.

The wide range of negative to positive δ34S sulfide values and the narrow range of δ34S sulfate compositions for the Halo prospect (Figure 5.5) indicates mineral

2- deposition from a relatively oxidized, sulfate dominant (i.e., H2S/SO4 < 1) magmatic- hydrothermal fluid (Ohmoto and Rye, 1979; Rye, 1993).

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This study

5.6 Summary and Conclusions

Based on the existence of saturated NaCl, the minimum pressure and temperature are estimated to be about 43 bars and 280oC and 10 bars and 182oC, during precipitation of quartz+pyrite+chalcopyrite+magnetite vein (Stage I Vein) and quartz vein associated potassic and silicic alteration, respectively. The homogenization temperature of quartz+galena+sphalerite+pyrite+chalcopyrite vein (Stage II vein) ranging widely from 174 to 306oC suggests boiling and the salinity ranges from 0.35 to 2 wt. % NaCl equivalent. In a boiling system, a pressures of about 13bars, 20bars,

20bars and 13bars are estimated for the dilute aqueous solution of 174oC, 201oC,

201oC and 174oC from quartz vein associated with galena, sphalerite, pyrite, chalcopyrite; quartz vein associated with pyrite, goethite, chalcopyrite; quartz vein

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associated with pyrite, sphalerite, chalcopyrite; and quartz vein associated with molybdenite, pyrite, respectively. The δ34S value of sulfide at the Halo prospect (about

+3‰), indicating that mineralization at the Halo prospect was magmatic in origin.

References

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Hoefs, J. (2009) Stable Isostope Geochemistry. Springer-Verlag., Berlin Heidelberg,

1-285.

Imai, A. (2000) Genesis of the Mamut porphyry copper deposit, Sabah, East Malaysia.

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Imai, A. (2005) Evolution of hydrothermal system at the Dizon porphyry Cu-Au

deposit, Zambales, Philippines. Resource Geology, 55, 73– 90.

Imai, A. and Ohno, S. (2005) Primary ore mineral assemblage and Fluid inclusion

study of the Batu Hijau porphyry Cu-Au deposit, Sumbawa, Indonesia. Resource

Geology, 55, 239–248.

Nagano, K., Takenouchi, S., Imai, H. and Shoji, T. (1977) Fluid inclusion study of the

Mamut porphyry copper deposit, Sabah, Malaysia. Mining Geology, 27, 201-212.

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Ohmoto, H. and Goldhaber, M. B. (1997) Sulfur and carbon isotopes. In Barnes, H. L.

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Ohmoto, H. and Rye, R. O. (1979) Isotopes of sulfur and carbon, in Geochemistry of

Hydrothermal Ore Deposit. 2nd edn. (Barnes, H. L., ed.) John Wiley, 509–567.

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Polymetallic Vein Deposits and Porphyry Deposits in the Phum Syarung-Dok

Yong Fault Corridor, Ratanakiri Province, Cambodia. (Poster)

Roedder E. and Bodnar, R. J. (1980) Geologic pressure determinations from fluid

inclusion studies. Annual review of earth and planetary sciences, 8, 263-301.

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the metal budget of porphyry copper deposits. Nature, 399, 676–679.

Ulrich, T., Günther, D. and Heinrich, C.A. (1999) Gold concentrations of magmatic

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Ulrich, T., Günther, D. and Heinrich, C.A. (2002) The evolution of aporphyry Cu–Au

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Chapter 6: General Conclusions and Discussions

6.1. Comparison of porphyry copper deposit worldwide

6.1.1 Magmatism and Ore-bearing Intrusions at the Halo

As mentioned previously in chapter 3, many geological and geochemical features of the Halo prospect are consistent with typical porphyry copper deposit worldwide (Sillitoe, 1992; Groves et al., 1998, 2005) (Figure 6.1).

Figure 6 1 Porphyry copper deposits in the context of plate tectonics (Groves et al., 2005). Porphyry copper deposits commonly occur in both continental and island-arc orogenic settings. Based on Rb/Zr vs. Nb diagram, Halo prospect was formed island arc setting (Figure 6.1).

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The formation of hydrothermal ore deposits including porphyry deposits is closely link with subduction zone magmas. Magmatic fluid is the main source of metals and their ligands (Hedenquist and Lowenstern, 1994). Porphyry copper deposits are associated with magmas ranging from alkaline to low-K calkaline to shoshonitic, which from diorite to syenite porphyry stocks (e.g. Cline and Bodnar,

1991; Sillitoe, 2000; Silitoe, 2002; Lickford et al. 2007). Furthermore, host intrusions associated with porphyry copper deposits are closely associated oxidized and arc related to I-type magnetite series (Burnham an d Ohmoto, 1980; Hedenquist and

Lowenstern, 1994; Ishihara and Terashima, 1989, Imai, 2000, 2001, 2002; Sillitoe,

2010).

Data from this study show that the magma responsible for the ore-bearing intrusions in the Halo copper-molybdenum prospect is generally diorite to granodiorite in composition and belong to the medium-K calc-alkaline to high-K calc-alkaline series. Cline and Bodnar, (1991) reported that typical calc-alkaline magmas have sufficient copper, chlorine, water to produce economic porphyry copper mineralization as long as the important factors are present. Moreover, based on the geochemical classification of granitic rocks, magnetic susceptibility (Maniar and Piccoli, 1989,

Ishihara, 1977), and present of magnetite in rocks, the intrusive rocks in the Halo prospect are I-type magnetite series, considered to have formed by partial melting of igneous protoliths. It has also been described that I-type magnetite series are potentially more developed in base metals such as Cu or Mo (Sillitoe, 1992; Camus and Dilles, 2001). The intrusive rocks were generated in volcanic arc setting-based trace element and arc crustal thickness in the Halo prospect was probably <40km at the time of emplacement of the granitoids. Moreover, the fresh hornblende diorite and

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granodiorite and least altered of diorite granodiorite and granodiorite porphyry have low Al2O3/(FeO+MgO+TiO2) ratios and fall into field of partial melting of amphibolites (Patiño Douce, 1999), further indicating that they were mainly derived from partial melting of basaltic meta-igneous rocks. Based on geochemical features of the Halo prospect, the hydrous basaltic magmas interacted with the upper plate lithosphere and provide heat and volatiles to induce the partial melting of lower crust during magma mixing process.

The intrusive rocks in the Halo prospect display features of trace elements typical of the magmatism related to a subduction zone, such as enrichment of LILE and negative anomalies of Nb and Ti. Furthermore, based on the (La/Yb)N versus YbN diagram, the diorite and granodiorite plot in the field of post-Archean subduction- related granitoids (Martin, 1986). This is in the good agreement with the conclusion of

Taylor and Hayes, (1983) who assumed that the Southeast Asian margin was an

Andean-type magmatic arc (subduction of the western Pacific plate under the southeast Asian continental margin) from mid-Jurassic to mid-Cretaceous. Based on geological map in the Halo prospect, the Halo prospect are composed of felsic and intermediate intrusive rocks (Cretaceous) (Richardson et al., 2015). The Halo prospect in NE Cambodia lying on Dalat-Kratie Belt consists of Triassic to Cretaceous sedimentary rocks intruded by Cretaceous (125-75Ma) volcano-plutonic rocks. The

DKB extends across the region from Cambodia to southern Vietnam (Khin Zaw et al.,

2010). The Cretaceous belt is chronologically comparable to the plutono-volcanic rocks of the late stage of the Yanshanian Orogeny in SE China (140–65 Ma; Manaka et al., 2012). Thus this belt could have formed in a similar tectonic setting as a southern continuation of the Yanshanian belt, which was formed from the subduction of the

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Palaeo-Pacific Plate underneath the Eurasia Plate including Indochina Terrane such as southern Anhui in china; Tien Thuan in Vietnam, Okvau, North Kratie, Halo prospect in Cambodia (Thuy et al., 2004; Manaka et al., 2012; Qing et al., 2018).

The age of intrusive rock (Cretaceous) and geochemical results of the Halo porphyry copper-molybdenum prospect provide evidence for a continuation of an

Andean-type arc from SE China via Dalat-Kratie belt including Halo prospect. Based on the result above, it can conclude that the Halo porphyry copper-molybdenum was formed during mid-Jurassic to mid-Cretaceous associated with I-type granite affinity at shallow crust (Figure 6.2) similar to formation of Au-related magmatism in south

Anhui in south china (Hu et al., 2018); Dexing porphyry Cu–Mo–Au deposit in east

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China (porphyry copper-molybdenum-gold, porphyry-skarn-vein copper in south china and northwest china (Mao et al., 2005, 2006, 2008,209; Zhou et al., 2007; Li et al., 2010).

6.2 Formation of the Halo porphyry copper-molybdenum prospect

Genetic model for the Halo porphyry copper-molybdenum prospect is presented

(Figure 6.3). The Halo porphyry copper molybdenum prospect hosted in diorite, granodiorite, quartz feldspar porphyry, granodiorite porphyry, andesite porphyry, mafic dykes, aplite dykes, and felsic dykes. Quartz feldspar porphyry and granodiorite porphyry are consider as the main intrusive body and most favorable host copper- molybdenum mineralization. They intersected drill hole HD1 and HD2, are associated with potassic alteration and dominated by Cu-Fe sulfide mineralization, quartz vein stockworks and magnetite veins. Drill hole HD3 consists of sheared andesite at the top of the hole and transitioned to granodiorite cut by fine-grained mafic dykes. Alteration consists of phyllic and prophylitic alteration. Even though, this drill hole is absent of potassic alteration but it consists more quartz+molybedenite vein that associated with phyllic alteration and quartz+magnetite+chalcopyrite+pyrite associated with propylitic alteration if compare to drill hole HD4. The drill hole HD3 is close to ore body than drill hole HD4 because drill hole HD4 is dominated by unaltered hornblende granodiorite and hornblende diorite with weakly phyllic and propylitic alteration and lack of ore mineralization (Table 6.1).

According to petrography analysis and alteration index calculated from PER analysis, they indicate that the rocks in hole HD1 are mostly affected by hydrothermal alteration compare to another 3 drill holes HD2, HD3 and HD4 (Table 6.2). Potassic

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alteration are hosted in quartz feldspar porphyry and granodiorite porphyry but quartz feldspar porphyry are more altered than granodiorite porphyry. Moreover, the degree of phyllic alteration associated with quartz feldspar porphyry and dacite are higher than phyllic alteration associated with diorite, granodiorite and granodiorite porphyry in drill hole HD2, HD2, and HD3. The highly altered zone vectoring center of the hydrothermal system may represent the locus of mineralization. According to result that mention above, the Halo prospect is a porphyry copper-molybdenum prospect and drill hole HD1 and HD2 are situated close to the center of porphyry deposit than drill hole HD3 and HD4. Mineralization, alteration, copper and molybdenum concentration in each drill holes are summarized in Table 6.1 based on the results in previous chapter

2, 3, and 4.

Furthermore, the Halo prospect consists of hydrothermal anhydrite occur as vein and veinlet and magnetite anhydrite in least altered granodiorite porphyry (Chapter 4).

The occurrence of magnetite anhydrite and hydrothermal anhydrite indicates the magnetic hydrothermal system in the Halo prospect is highly oxidized and sulfur-rich with abundant sulfates similar phenomena of porphyry copper-molybdenum deposit in Qulong, Southern Tibet, China report by Xiao et al. (2011), porphyry copper deposit in Waisoi, Viti Levu, Fiji (Imai et al., 2007).

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Figure 6. 3 Genetic model for formation of Halo porphyry copper-molybdenum prospect. Sillitoe (2010) was used as reference. This Model: Not to Scale

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Table 6. 1 Summary on rocks, mineralization, and alteration, copper and molybdenum concentration in each drill holes (HD1 to HD4)

Drill Rocks Mineralization Alteration Cu-Mo hole (ppm)

HD1 Quartz feldspar qtz stockworks Alteration index (AI) Cu up to porphyry, dacite, veinlets, mag veinlet, of quartz feldspar 7,048 andesite and mafic qtz+mag+cpy porphyry : 11.8 to dykes veins,qtz+py+cpy+mag 32.3% and AI of Mo up to veins, qtz+mo veins, Dacite= 43.3 to 3,808 qtz+py+cpy+sp+ga 66.6% vein, disseminated Potassic and phyllic alteration

HD2 Granodiorite qtz+mo veins, AI of granodiorite Cu up to porphyry, diorite, qtz+cpy+py+mag+mo porphyry 5.1 to 877 vein, qtz+py+cpy 11.9%. felsic dykes, mafic veinlet, mag veinlets, Mo up to dyke, and aplite pyrite veinlets, cal Weak potassic and 5,297 dykes veinlet, anhydrite phyllic alteration veins, disseminated

HD3 Granodiorite, qtz+mo veins, Phyllic and propylitic Cu up to 96 diorite, felsic quartz+py+cpy+mo alteration dykes, mafic dyke, veins, Mo up to and by breccia qtz+mag+cpy+py vein, 1,945 vein. qtz+py+cpy+sp+ga vein, disseminated

HD4 Hornblende massive py, Mostly dominated by No data granodiorite, qtz+cpy+sp+ga veins unaltered hornblende hornblende diorite and qtz+anh+py veins granodiorite, rhyolite dykes, and hornblende diorite. mafic dykes. propylitic and phyllic alteration

Based on results above: Drill holes HD1 and HD2 are situated close to the center porphyry deposit than drill holes HD3 and HD4.

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6.3 General conclusion

Major conclusion for this research area are:

1. The Halo copper-molybdenum porphyry prospect is predominately by diorite,

granodiorite, quartz feldspar porphyry, granodiorite porphyry, andesite

porphyry, mafic dykes, andesitic dykes, aplite dykes, and rhyolite dykes.

2. The intrusive rocks and volcanic rocks plot within the domains of volcanic

arc granite based on spider diagram, (Y+Nb) versus Rb diagram, and Y versus

Nb diagram. The intrusive rocks have medium-K calc-alkaline to high-K

calc-alkaline series.

3. A variety of mineralization styles are disseminated sulfides, veinlets, and

stockworks veins. Ore minerals are dominated by pyrite, chalcopyrite, and

molybdenite, with minor magnetite, sphalerite, hematite, pyrrhotite, and

galena.

4. Based on crosscutting relationships and mineralization of veins, the ore-

forming process is divided into four stages such as: Stage I quartz+magnetite±

±chalcpyrite±pyrite±molybdenite±pyrrhotite vein; Stage II quartz+

molybdenite±chalcopyrite±pyrite vein; Stage III quartz+pyrite±chalcopyrite

±sphalerite±galena vein; and Stage IV quartz±calcite±anhydrite±gypsum

±pyrite±chalcopyrite vein. Hydrothermal alteration is characterized by

potassic, prophylitic and phyllic alterations.

5. Halite-bearing fluid inclusions presented in Halo prospect. Similar

phenomena have been reported from several porphyry deposits.

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34 34 6. The range of δ Ssulfide values and δ Ssulfate values from the Halo copper-

molybdenum porphyry prospect are similar to the range typical for porphyry

copper deposits worldwide.

7. These feature of Halo porphyry copper-molybdenum prospect are consistent

with porphyry system worldwide.

6.4 Recommendation for further research

In order to better constrain the genetic model for porphyry mineralization throughout the Halo prospect, additional studies further to the work conducted in this thesis should be considered:

. Detail study on diamond drill cores should be carried out to interpret the

subsurface alteration and mineralization that would be define economic

potential as well as to develop the accurate model of the mineralization area.

. XRF analysis should be conducted more in order to know the zoning of

mineralization.

. Fluid inclusion and sulfur isotope study related to alteration and mineralization

also should be done more in each stage of vein and alteration in order to trace

the source of the hydrothermal fluids and their evolution and make genetic

model of deposit.

. Intrusive and volcanic rocks associated with mineralization and alteration

should be dated in order to predict period of magmatic activity and hence the

time of mineralization/alteration as well.

. Further δ18O and δD analyses on main-stage alteration minerals (e.g., biotite,

muscovite and chlorite) would improve constraints on the various types of

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hydrothermal fluids involved in alteration of the rocks and ore formation, and

on the amount of mixing that occurred between the different fluids.

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Appendix

Appendix 1: Description of outcrop samples and XRD Analysis

Note: ALT 02, ALT03, ALT05, ALT07, ALT10 are diorite and have the same composition of mineral and ALT11-ALT18 are granodiorite.

No Name of Field Description Pictures rock ALT01 Oxidized Reddish oxidized rock rock Located in phyllic alteration. It consists of illite by XRD. The concentration of copper is higher than un-oxidized sample like diorite and granodiorite ATL02-ALT28

Cu=1652ppm

ALT03 Diorite Phyllic alteration: sericite+chlorite It is dominated by quartz, feldspars, plagioclase, hornblende and also some pyrite.

ALT05 Diorite Phyllic alteration: sericite+chlorite It is dominated by quartz, feldspars, plagioclase, hornblende and also some pyrite.

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ALT06 Silicified Silicic alteration: quarz+sericite rock

ALT10 Diorite Phyllic alteration: Sericite+chlorite+smectite It is dominated by quartz, feldspars, plagioclase, hornblende and pyrite.

Ore minerals: pyrite, chalcopyrite, pyrrhotite.

ALT11 Granodiorite Phyllic alteration Dark greenish medium grained granodiorite consist of quartz, plagioclase with minor hornblende. Ore minerals: pyrite, chalcopyrite, pyrrhotite. Hornblende partially altered to chlorite and plagioclase altered to sericite.

ALT13 Granodiorite Phyllic alteration: sericite+chlorite

Similar with ALT11

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Appendix

ALT17 Granodiorite Phyllic alteration Sericite+chlorite It is medium to coarse grain and consists of quartz, plagioclase, feldspar, biotite and hornblende. Disseminated: Pyrite, chalcopyrite, pyrrhotite and covellite.

Location: 0756848E, 1502288N

ALT18 Granodiorite Phyllic alteration Sericite+chlorite It is intermediate rock consists of quartz, plagioclase, feldspar, biotite and hornblende. Disseminated: Pyrite, chalcopyrite, pyrrhotite and covellite.

Location: 0756758E, 1502265N Elevation: 188m

ALT19 Andesite Phyllic alteration Sericite+chlorite It is a fine-grained, extrusive igneous rock, consists mainly of plagioclase with other minerals such as hornblende, pyroxene and biotite.

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ALT20 Granodiorite Phyllic alteration Sericite+chlorite It is dominated by quartz, feldspar, and hornblende. Pyrite veinlet Disseminated: Pyrite, chalcopyrite, pyrrhotite and covellite.

Location: 0756746E, 1502258N Elevation: 188m

ALT21 Granodiorite Phyllic alteration Sericite+chlorite

Almost altered to silicified rock. It consists of quartz, plagioclase and feldspar

Ore mineral: pyrite, chalcopyrite, covellite,

ALT22 Silicified Silicic alteration: rock quartz

ALT23 Silicified Silicic alteration: rock Quartz

Ore mineral: pyrite, chalcopyrite, covellite, hematite

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ALT27 Silicified Silicic alteration rock It is dominated by quartz, feldspars, plagioclase and also some pyrite. But it most abundant of quartz.

Location: 0756931E, 1502344N

ALT28 Pyrite In silicic alteration zone bearing quartz

Ore mineral: pyrite, chalcopyrite and galena

151

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153

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157

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159

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Appendix

Representation of X-ray diffraction pattern of bulk rock/random powder analysis Qtz: quartz, Il: Illite, Fsp: Feldspar, Pl: plagioclase, Ser: Sericite, Kao: Kaolinite, Chl: chlorite, Sm: Smectite

Appendix 2: Sample Description and XRD Results in Drill hole HD1

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Reddish Clay (Cu=329ppm, Mo=497ppm); (2) dacite associated phyllic alteration (Cu= 3883ppm, Mo=168ppm) (3) quartz stockwork veins hosted dacite (Cu=, 4336ppm, Mo=78ppm) associated with phyllic alteration; (4) quartz veinlets hosted in dacite with disseminated chalcopyrite, pyrite (Cu=7048ppm, Mo=150ppm); (5) feldspar porphyry disseminated with pyrite and chalcopyrite , (5) quartz vein hosted dacite associated with phyllic alteration (867ppm, Mo=107ppm) , (6) quartz feldspar porphyry, (7) pyrite veinlet hosted quartz feldspar porphyry associated in phyllic alteration; (8) quartz+molybdenite+pyrite vein was cut by pyrite veinlet (Cu=276ppm, Mo=1003ppm). Note: The number after D1 are number of depth in drill hole HD1.

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(9) quartz feldspar porphyry associated with potassic as teration (Cu=1536, Mo=80ppm); (10) quartz feldspar porphyry with quartz+magnetite+chalcopyrite +pyrite veinlet show pinky groundmass K-feldspar in potassic alteration (Cu=2204ppm, Mo=107ppm); (11) quartz+magnetite+pyrite +chalcopyrite veinlet in feldspar porphyry associated with potassic alteration (Cu=1668ppm, Mo=n.d); (12) quartz veinlets and magnetite veinlets in andesite associated potassic alteration (Cu=399ppm, Mo=n.d). Note: The number after D1 are number of depth in drill hole HD1.

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(13) Potassic altered andesite and quartz feldspar porphyry with quartz+magnetite+chalcopyrite+pyrite vein, andesite intruded by quartz feldspar porphyry (Cu=2670, Mo=n.d in vein); (14) quartz+chalcopyrite+pyrite+magnetite vein cut quartz feldspar porphyry associated potassic alteration (Cu=1669, Mo=34ppm disseminated in rock, Cu=1869ppm, Mo=181ppm in vein with rock); (15) quartz+magnetite+chalcopyrite+pyrite on the margin of vein and biotite+chlorite +chalcopyrite+pyrite in centerline of quartz vein hosted in quartz feldspar porphyry show potassic alteration (Cu=511ppm, Mo-181ppm in rock) (16) quartz+magnetite +K-feldspar cuted by pyrite+chalcopyrite veinlet hosted in andesite showing potassic alteration (Cu=371ppm, n.d). The number after D1 are number of depth in drill hole HD1.

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167

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168

Appendix

X-ray diffraction pattern of bulk rock and oriented samples ; Qtz: quartz, K-fsp: K- feldspars, Pl: plagioclase, Chl: chlorite, Ser: sericite, Kao: Kaolinite.

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Appendix 3: Sample Description in Drill hole HD2

Core samples in HD2: diorite (depth 33.10-37.20mm); felsic dyke (completed silicified) and fine grained greenish gray andesite with calcite veinlet (depth: 160.48- 165m)

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Granodiorite porphyry with pinky xenolith (fine grained of K-feldspar) possible aplite (depth: 226.14m-231m); light pinky granodiorite porphyry cut by quartz+ chalcopyrite+pyrite+magnetite+molybdenite vein and gypsum vein (depth: 251.80- 257.23m).

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Granodiorite porphyry cut by quartz+molybedenite vein and calcite veinlet (358.40- 369m), show potassic altered groundmass with patchy biotite, hornblende altered to chlorite and feldspar replaced by epidote.

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Diorite with pyrite filling fracture and pyrite and chalcopyrite disseminated associated with phyllic alteration (Cu=133ppm, Mo=n.d), (2) Diorite (Cu=277ppm, Mo=n.d); (3) andesite dyke; (4) granodiorite light pink with xenolith of fine grained K-feldspar (possible aplite); (5) pinky light green granodiorite porphyry; (6) pinky granodiorite porphyry associated with potassic alteration show potassic altered groundmass with patchy biotite, chlorite altered hornblende, epidote altered feldspar, pyrite and chalcopyrite

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