臺灣東部和平地區開口充填方解石的液體來源之研究

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(1)國立臺灣師範大學理學院地球科學研究所碩士論文 Department of Earth Sciences National Taiwan Normal University Master Thesis. 臺灣東部和平地區開口充填方解石的液體來源之研究 Study of Fluid Source of Open-Filling Calcites in the Hoping Area, Eastern Taiwan. 阮氏梅 Nguyen, Thi Mai 指導教授：葉恩肇博士 Advisor: Yeh, En-Chao Ph.D.. 中華民國 107 年 1 月 January, 2018.

(2) Acknowledgements I would like to express my deep gratitude to Prof. En-Chao Yeh for providing me with the opportunity to work on an interesting research topic. I have been extremely lucky to have a supervisor who encouraged and directed guidance throughout my time as his student. I would like to thank to Prof. Horng-Sheng Mii, Prof. Jiann-Neng Fang, Prof. HueiFen Chen, Prof. Pei-Ling Wang, Prof. Ryu Uemura and and their assistants, special thanks to Yu-Ho Lee and Tzu-Hao Huang for their laboratory assistances. Thanks to Wayne Lin of Material and Chemical Research Laboratories, Industrial Technology Research Institute and lab-mates (Ping-Chuan Chen, Hao-Ding Cin and Po-Han Ho) helped me to collect samples in Hoping River, Taiwan. I give deep thanks to Professors and staff members at Department of Earth Sciences. I am deeply thankful to Directors of the Institute of Geophysics, Earthquake Information and Tsunami Warning Center, especial to Prof. Nguyen Hong Phuong who encouraged to continue my graduate studies. I appreciated thank to Chao-Yan Lin, Yung-Tian Chiu and Zhi-Wei Wu and classmates for their friendship and efforts during my time in Taiwan. I am so grateful to the National Taiwan Normal University scholarship for making it possible for me to study here. Finally, many thanks to my family and my friends for their patience and invaluable support during my long lasting study in a distant country.. i.

(3) Abstract The aim of this study is to evaluate whether the meteoric water can penetrate into the deep crust of Hoping area, eastern Taiwan. To test the hypothesis, this work investigated the fluid source of open-filling carbonates deposited on the fracture surfaces with various attitudes via Raman spectroscopy, stable isotope analysis, fluid inclusion and clumped isotope analysis. In details, Raman spectroscopy can identify the type of openfilling carbonates, analysis of oxygen and carbon stable isotopes of carbonate deposits can help to delineate the possible fluid sources. Fluid inclusion analysis can provide temperature information of open-filling carbonates. The clumped isotope of carbonates will further attain the absolute temperature for estimating the oxygen isotope of fluids. With Raman spectroscopy, calcite is identified in type A, B and Others deposits although their occurrences are quite different. Type A and Others is thick film and crystal types and is deposited on oblique-foliation fractures. Type B is thin membrane type and is deposited on parallel -foliation fractures. No dolomite is found in the carbonate deposit. Also quartz is identified in specific intervals. The carbon and oxygen isotopes of Type A, type B and type Others in meta-granite cores did not hold relationship with depth. Type A has smaller 18O with bigger 13C, while type B has similar carbon isotope with varied oxygen isotope. The oxygen isotope of marble lenses have constant values with scattered carbon isotope. The carbon and oxygen isotope pattern of marble lenses has a trend different from that of open- filling calcites. The 18O values of marble lenses from metagranite cores are consistent with those of marble lenses from marble outcrops. Fluid inclusion analysis of calcite crystals was applied to measure the homogenization temperature (Th) of location A42_2, sample O06 and location O19_2.. ii.

(4) Their Th ranges 164 - 231 ℃, 106 - 305 ℃ and 160 - 211 ℃, respectively. Calcite was formed at 3 – 6 km below the surface with the geothermal gradient of 30–60°C/km. Assuming that the oxygen of open-filling calcites are equilibrium with that of fluid at Th, the calculated 𝛿18O fluid of location A42_2 and A42_3 ranges from -13.33 to 9.52‰VSMOW and -13.08 to -8.89‰VSMOW, respectively, indicative of meteoric water from 500 to 3000m elevation. The average δ18O fluid of sample O06 is -6.26 ± 2.62‰VSMOW indicate formation from meteoric water at elevation less than 4000m. These results show that meteoric waters dominate the fluid phase in open-filling calcites. However, the calculated 𝛿18O fluid of location O19_1 were mixed meteoric water with either magmatic sources or metamorphic water. The clumped-isotope temperature of sample A42 and O19 is 209 ℃ and 92 ℃, respectively. The calculated oxygen isotope fluid of sample A42 and O19 is similar with local meteoric water at 300m elevation. Key words: oxygen and carbon isotope, clumped isotope, fluid inclusion, meteoric water, eastern Taiwan.. iii.

(5) Table of Contents Acknowledgements ............................................................................................................. i Abstract ............................................................................................................................. ii Table of Contents .............................................................................................................. iv List of Tables .................................................................................................................... vi List of Figures .................................................................................................................. vii Chapter 1. Introduction ...................................................................................................... 1 1.1Motivation ................................................................................................................. 1 1.2 Tectonic Setting and Geological Background ........................................................... 3 1.3 Sample descriptions .................................................................................................. 8 Chapter 2. Methods .......................................................................................................... 13 2. 1 Raman spectroscopy .............................................................................................. 13 2.2 Oxygen and carbon isotope analysis ....................................................................... 15 2.3 Fluid inclusion analysis .......................................................................................... 17 2.4 Clumped-isotope analysis ....................................................................................... 21 Chapter 3. Results ............................................................................................................ 26 3.1 Raman spectroscopy ............................................................................................... 26 3.2 Compositions of carbon & oxygen isotope analysis ................................................ 29 3.3 Fluid inclusion analysis .......................................................................................... 34 3.4 Clumped isotope analysis ....................................................................................... 39 Chapter 4. Discussion ...................................................................................................... 42 4.1. δ18O and δ13C compositions of open-filling calcite ................................................. 42 4.2 The compositions of marble .................................................................................... 46 4.3 Calculated δ18O fluid .............................................................................................. 54 4.4 Meteoric water ....................................................................................................... 59 iv.

(6) 4.5 Fluid sources .......................................................................................................... 64 Chapter 5. Conclusion ...................................................................................................... 68 References ....................................................................................................................... 70 Appendix A The distribution of open-filling fracture and marble lenses in core................ 74 Appendix B. The coordination of marbles and distance of marbles and meta-granites in outcrops ............................................................................................................. 76 Appendix C The carbon and oxygen isotope of core samples with depth .......................... 77 Appendix D. Carbon and oxygen isotope composition of marbles and marble lenses in outcrop ............................................................................................................... 84 Appendix E. The homogenization temperature of open-filling calcites ............................. 85 Appendix F. The calculated oxygen isotope compositions of open-filling calcites ............ 86 Appendix G. Expected temperature based on δ18O and δ18O fluid of marble lenses .......... 88 Summary of questions/answers and suggestions ............................................................... 90. v.

(7) List of Tables Table 1 Raman shifts of the reference minerals ................................................................ 14 Table 2 Abundances of isotoplogues of carbon dioxide assuming a random distribution…23 Table 3 Statistics of carbon and oxygen isotope compositions .......................................... 31 Table 4 Statistics of carbon and oxygen isotope compositions .......................................... 33 Table 5 Statistics of homogenization temperatures (Th). .................................................. 35 Table 6 Clumped-isotope compositions and depth of A42 and O19 .................................. 39 Table 7. The δ18O values in Taiwan at the different elevations base on previous work ...... 59. vi.

(8) List of Figures Figure 1.1 Summary schematic of the fluid flow regime in the Southern Alps .................... 2 Figure 1.2 Geologic map of Taiwan. .................................................................................. 3 Figure 1.3 Geological Map of Hoping River...................................................................... 6 Figure 1.4 Photos of marble outcrops in upstream and downstream. ................................... 7 Figure 1.5 Photo of a) open-filling fracture, b) close-filling fracture ................................... 8 Figure 1.6 Open filling fracture of type A, type B and type others ...................................... 9 Figure 1.7 The red line is in the right of the blue line ....................................................... 10 Figure 1.8 Distribution of open-filling fracture ................................................................. 11 Figure 1.9 Marbles and marble lenses .............................................................................. 12 Figure 2.1 Image of Labram HR800 ................................................................................. 13 Figure 2.2 Raman spectrum of reference minerals ............................................................ 14 Figure 2. 3 a) Carbonate powders were collected by micro miller. .................................... 16 Figure 2.4 Serial photomicrographs of primary inclusion in calcite.. ................................ 18 Figure 2.5 The carbon and oxygen isotopes ................................ …………..…………….19 Figure 2.6 Prepare thin section for fluid inclusion analysis ............................................... 20 Figure 2.7 THMS600 Heating and Freezing Microscope Stage Axio Scope A1 ................ 21 Figure 3.1 Raman spectra of calcite of type A, type B and type Others ............................. 27 Figure 3.2 Raman spectra of calcite of marble lenses ....................................................... 28 Figure 3.3 Photo and Raman spectra of (a) quartz and (b) chlorite .................................... 29 Figure 3.4 The plot of stable isotopes of open-filling calcite and marble lenses ................ 30 vii.

(9) Figure 3.5 The carbon isotope values versus depth. .......................................................... 31 Figure 3.6 The oxygen isotope values versus depth. ......................................................... 32 Figure 3.7 The carbon and oxygen isotope pattern of marbles and marble lenses .............. 34 Figure 3.8 Inclusion size of location A42_2 and O19_2. .................................................. 36 Figure 3.9 Homogenization temperature versus depth. ..................................................... 37 Figure 3.10 Histograms showing homogenization temperatures Th………………………38 Figure 3.11 The carbon isotope value of sample A42 and O19 versus depth ..................... 40 Figure 3.12 The oxygen isotope value of sample A42 and O19 versus depth. ................... 41 Figure 4.1 The carbon and oxygen isotope of open-filling calcites.................................... 43 Figure 4.2 The carbon and oxygen of vein calcite with depth in TCDP work .................... 44 Figure 4.3 Homogenization temperature (Th) versus depth .............................................. 45 Figure 4.4 The compositions of carbon and oxygen isotope in Hoping core and outcrop samples from previous study . ............................................................................... 46 Figure 4.5 Mean pole of sample orientation in upstream and downstream ........................ 48 Figure 4.6 Projection of marble and meta-granite in outcrops. .......................................... 49 Figure 4.7 The carbon and oxygen isotope with distance .................................................. 50 Figure 4.8 The 18O fluid of marble lenses and expected temperature............................... 51 Figure 4.9 The 13C and 18O values of fresh-water carbonates and marine limestones .... 52 Figure 4.10 Summary plot of stable isotopes and temperatures ......................................... 54 Figure 4.11 The calculated oxygen isotope fluid of open-filling calcites versus Th. .......... 57 Figure 4.12 The calculated oxygen isotope fluid of open-filling calcites ........................... 58 viii.

(10) Figure 4.13 Plot of 18O value with elevation in Taiwan. ................................................. 60 Figure 4.14 Plot of D and 18O compositions of location O19_2 .................................... 61 Figure 4.15 The O fluid of sample A42, O06 and O19 vs different elevation . ............. 63 Figure 4.16 The oxygen isotope and the calculated oxygen of fluid. ................................. 67. ix.

(11) Chapter 1. Introduction 1.1 Motivation The geochemical composition of mineralizing fluids depends on the chemical and isotopic features of the feeding fluids and host rocks, as well as by the pressure and temperature which control the relocation of chemical species in solution and the isotope repartition by exchange reactions of solutes with water (Vaselli et al., 2012, p.77). Therefore, the geochemical composition of precipitates in equilibrium with solution may be modeled, allowing to estimate the chemical-physical conditions at the time of vein formation. The origin of waters can be determined as a characteristic or conservative parameter based on the water molecule itself such as the D/H or. 18. O/16O ratio (Sheppard,. 1986, p.165). Waters, brines or aqueous fluids in geologic systems include ocean, meteoric water, metamorphic water and magmatic fluids. Fracture-filling calcite is the best candidate to constrain the geochemical features of fluid reservoirs and post-depositional and syn-tectonic fluid processes (Wang et al., 2010, p.251). The incursion of meteoric fluids into the ductile portion of the crust was analyzed in previous study (Menzies, et al., 2014, p.10) in the Southern Alps of New Zealand (Fig 1.1). The oxygen and hydrogen stable isotope of vein quartz and chlorite were used to examine fluid flow and homogenization temperatures were estimated from fluid inclusions analyses. The calculated oxygen value ranges -2.3 to -8.7‰VSMOW. These results indicated that one of the estimated fluid is purely metamorphic in origin during the precipitation of ductile deformed quartz vein but the hydrothermal systems are dominated by meteoric water in the rocks.. 1.

(12) The goal of this study is to investigate whether the meteoric water can penetrate into the deep crust of Hoping area, eastern Taiwan as previous work, this study used carbon and oxygen isotope analysis to determine the original deposition environment and fluid source of open-filling minerals. Fluid inclusions and clumped-isotope were also applied to directly reconstruct the formation temperature and fluid sources were further evaluated with openfilling calcites.. Figure 1.1 Summary schematic of the fluid flow regime in the Southern Alps. (Menzies et al., 2014, p.10). The brittle to ductile transition zone (BDTZ).. 2.

(13) 1.2 Tectonic Setting and Geological Background. Figure 1.2 Geologic map of Taiwan showing the Coastal Plain province (I) in yellow, the Western Foothills province (II) in pink, the Hsuehshan Range province (III) in brown, the Backbone Range province (IV) in purple, the pre-Tertiary metamorphic basement as violet, Longitudinal Valley province (V) in white and the Coastal Range province (VI) in orange. Blue square is the study. Inset map indicating oblique collision between the Eurasian Plate and Philippine Sea Plate (Ho, 1988). 3 đ.

(14) Taiwan is a modern mobile belt, formed by the oblique convergence between the Philippine Sea Plate and the Eurasian Plate (Ho, 1988, p. 11), with a rate is 82 mm/year (Yu et al., 1996, p. 41) (Fig 1.2). As the subduction in the south offshore of Taiwan, the inferior of Philippine Sea Plate has formed the Luzon Arc; and in the northern Taiwan, the Philippine Sea plate subducts beneath the Eurasian plate resulting in the Ryukyu arc (Fig 1.2). Taiwan located on the junction between the Ryukyu Arc and the Luzon Arc, during the Tertiary has been affected by the eastward pulsation of the plate tectonics (Juan, 1975, p.197). Generally, Taiwan can be divided into six geologic provinces (Fig 1.2). From west to east, they are the Coastal Plain (I), the Western Foothills (II), the Hsueshan Range (III), the Backbone Range (IV), the Longitudinal Valley (V) and the Coastal Range (VI). The Coastal Plain (I) is located on the western coast towards the Taiwan Strait. It is composed of young Quaternary clastic sediments. Lateritic and gravel terraces have been formed. In the southwestern part, there is also carbonates and coral reefs. The Western Foothills (II) is characterized by a series of west-facing fold and thrust sheet. It consists largely the Oligocene to Pleistocene fluvial to shelf clastic sediment (Chou, 1973, 1980; Huang and Cheng, 1983). In the Western Foothills, it occurs numerous earthquakes which evidenced the Taiwan Mountain building process. The Central Range which comprises the main body of the Taiwan orogeny, includes the Hsuehshan Range and Backbone Range. The Hsuehshan Range province (III) is composed of a continuous succession of Eocene to Miocene age. The Backbone Range is located to the west by the Hsuehshan Range and to the east by the Longitudinal Valley. In this location, it formed most of highest mountains in Taiwan. The Central Range (IV) is comprised tectonized pre-Tertiary basement (Tananao Schist) and a metamorphosed Cenozoic sedimentary cover. “Tananao Schist” is a term used for all the basement rocks in the metamorphic complex of Taiwan. The origin of the 4.

(15) metamorphism and diastrophism are identified in: (1) the Tananao Schist formation of Late Mesozoic during ~110 to 77 Ma (Jahn and Liou, 1977; Jahn et al., 1986; Lan et al., 1990; Lo and Yui, 1996; Lan et al., 1996) or during 95-82 Ma (Lo and Onstott, 1995) in the western the Tailuko belt low P/high T and the Yuli belt high P/low T in the eastern Backbone Range. Rocks in Tailuko belt included: schist, gneiss, migmatite (39-40 Ma) (Ho, 1988, p. 36), metamorphosed limestone, green schist, siliceous schist and amphibolite (82.5-86.5 Ma). The Yuli belt is composed of epidote amphibolite (79 Ma) (Ho, 1988, p. 36), glaucophane schist (8-14 Ma) (Ho, 1988, p. 36), epidote amphibolite (4.6 Ma) (Ho, 1988, p. 36), and mica schist (6-10 Ma) (Ho, 1988, p. 36). Yuli belt included the mafic tectonic fragments and metamorphosed oceanic rocks (Ho, 1988, p. 37). The Cenozoic sedimentary cover lies uncomfortably the pre-Tertiary basement with age of (Paleocene, Miocene and Eocene). The Longitudinal Valley (V) is deformed sediments between the Eurasian Continental Margin and the Philippine Sea Plate. It is located between the Central Range to the west and the Coastal Range to the east (Ho, 1988; Tsai, 1986). The Longitudinal Valley province hosts a multitude of active faults (i.e. the Longitudinal Valley Fault, the Luyeh Fault and Chihshang Fault). The Coastal Range in eastern Taiwan, is accreted portion of the Luzon arc-trench system. Hoping area lies in the northern end of Tailuko belt of the Backbone Range of Taiwan. The main rock in the area includes not only marble but also gneisses. The local geological map shows that meta-granite lies in between marbles (Fig 1.3). Star area is the drill site where core samples were collected. Crossed areas are where marbles and marbles lenses were collected in upstream and downstream (Fig 1.4 a & b).. 5.

(16) Figure 1.3 Geological Map of Hoping River. Star and cross point the locations of drilling site and outcrops, respectively.. 6.

(17) Figure 1.4 Photos of marble outcrops in upstream and downstream.. 7.

(18) 1.3 Sample descriptions In order to evaluate fluid sources of open-filling minerals, 75 open-filling minerals and 8 marble lenses were collected from meta-granite cores at the depth from 43 to 603 m. The distribution of open-filling fracture samples were listed in Appendix A. Based on detailed core examination (Lin, 2015, p.22), fracture-filling minerals in the meta-granite can be divided into two groups: open-filling and close filling (Fig 1.5).. Figure 1.5 Photo of a) open-filling fracture, b) close-filling fracture (Lin, 2015, P.54). 8.

(19) Open-filling fracture including 3 types are type A, type B and type Others. Type A and Others are oblique to foliation; type B is parallel to foliation. In open-filling fractures, minerals appear in all samples but their minerals are different. Type A and type others have thick minerals and crystals as well; type B has thin mineral (Fig 1.6).. Figure 1.6 Open filling fracture of type A, type B and type others. 9.

(20) Figure 1.7 The red line is in the right of the blue line showing the top and the bottom of core sample; dash lines showing the foliation. Based on tendency analysis of previous study (Lin, 2015, p.78), compared with attitudes of open-filling parallel- foliation (type B), attitudes of open-filling obliquefoliation (type A and Others) is more consistent with predicted attitudes of higher dilation tendency analyzed from in-situ stress data, suggesting that mineral deposit oblique to foliation might precipitate in the current stress state (Fig 1.8).. 10.

(21) Figure 1.8 Distribution of open-filling fracture (Lin, 2015, p.78) 11.

(22) For investigating original isotope signals of marble and possible isotope evolution of marble lenses, twenty-four marbles were collected in both upstream (Fig 1.9a) and downstream (Fig 1.9b) of Hoping and two marble lenses were sampled in upstream. The outcrop coordination of marbles and marbles lenses in upstream and downstream were listed in Appendix B.. a). b) Figure 1.9 Marbles and marble lenses were collected in a) upstream b) downstream of Hoping area. 12.

(23) Chapter 2. Methods 2. 1 Raman spectroscopy For calculating the oxygen isotope of fluid equilibrated with paleo-temperature inferred from other information, we need to know the type of minerals before damaging the samples for other analyses. Several methods can identify mineral types such as infrared spectroscopy, X-ray diffraction, and Raman spectroscopy. In this study, Raman spectroscopy was used to identify carbonate minerals among dolomite, aragonite, magnesite and calcite because this method is non-destructive and gives information about the molecular composition and crystal structure of the compounds.. Figure 2.1 Image of Labram HR800.. Samples were measured by a Horiba Jobin-Yvon HR800 in National Taiwan Museum (Fig 2.1). Raman spectra were excited by a standard He-Ne laser 633nm at a resolution of 2 cm-1 in the range between 100 and 4000cm-1 at room temperature. In order 13.

(24) to improve the signal to noise ratio, the highest magnification was repeated acquisition. Spectra were calibrated using the 520 cm-1 line of a silicon wafer (Sun et al., 2014, p.159). The differences of Raman shifts among carbonate minerals like calcite (CaCO3), dolomite ((Ca,Mg(CO3)2), Magnesite (MgCO3) and aragonite (CaCO3) have been detailed with Raman spectroscopy showed in Fig. 2.2 and Table 1.. Figure 2.2 Raman spectrum of reference minerals a) calcite (CaCO3); b) dolomite ((Mg,Ca(CO3)2); c) Aragonite (CaCO3) and d) Magnesite (MgCO3). Table 1 Raman shifts of the reference minerals Mineral. Wavenumber (cm-1). Dolomite. 176, 301, 724, 1100. Aragonite. 142, 152, 179, 205, 247, 260, 701, 1084. Magnesite. 283, 329, 738, 1094. Calcite. 155, 280, 711, 1086. 14.

(25) The Raman spectra of aragonite (CaCO3) has been identified with bands at 142, 152, 179, 205, 701 and 1084 cm-1 (Ferrer et al., 2013, p.83). The fundamental bands of magnesite (Mg,CaCO3) are located at 283, 329, 738 and 1094 cm-1 (Bischoff et al., 1985, p.583). The dolomite bands are at 176, 301, 724 and 1100 cm-1 (Ferrer et al., 2013, p.83). Raman shifts calcite (CaCO3, trigonal), are located at 155, 280, 711 and 1086 cm-1 (Ferrer et al., 2013, p.83).. 2.2 Oxygen and carbon isotope analysis Before conducting a fluid inclusion and clumped-isotope analysis, the carbon and oxygen isotopic compositions of the prepared samples were measured (i.e. their δ18O and δ13C values). In details, analysis results of oxygen and carbon stable isotopes of carbonate deposits can help to delineate the fluid oxygen isotope with corresponding temperature of mineral formation and further decipher the possible fluid sources. A total of 99 samples were selected for carbon and oxygen isotopic analyses, which including 65 carbonates and 8 marble lenses from cores and 24 marbles and 2 marble lenses from outcrops. Each sample was drilled three locations and each location was took three powders with different depths if possible (Fig 2.3).. 15.

(26) Figure 2. 3 a) Carbonate powders were collected by micro miller. b) Each sample was drilled three locations and each location was took three powders with different depths. Coin is for scale.. Carbonate powders were reacted with 100% H3PO4 at 90℃ to liberated CO2 gas. The isotopic compositions are expressed in 𝛿-notation that is defined as: Rsample. δ = ( Rstandard − 1) x1000‰. (Eq.1). Where R is the ratio of 18O/16O or 13C/12C Rsample is the isotope ratio of samples Rstandard is the isotope ratio of the standard All stated carbon isotopic ratios are C with respect to Vienna Pee Dee Belemnite (VPDB), and oxygen isotopic ratios are with respect to Vienna Standard Mean Ocean Water (VSMOW). The isotopic analyses of calcite were measured on a Micro Mass Iso-Prime Isotope Ratio Mass at the Department of Earth Sciences, National Taiwan Normal University. In this study, the standard oxygen and carbon isotope values of (NBS-19-2 were -2.20‰ and + 1.95‰and the and C values of CO1 were -2.45‰ and +2.45‰, respectively with precision less than 0.1‰. For oxygen isotope analysis, the. 16.

(27) relationship between VPDB and VSMOW is defined as (IAEA 1983): VSMOW = 1.0308618OPDB + 30.86‰).. 2.3 Fluid inclusion analysis Fluid inclusion can be used to decipher for the temperature of past geologic events. Each rock may contain billions of tiny fluid inclusions (Edwin Roedder, 1984, p7). Most of these billion inclusions may record the same temperature. Basically the idea of fluid inclusions for geo-thermometry come from the result of differential shrinkage between the host mineral and the inclusion fluid during cooling from the temperature of trapping to the temperature of observation. The fluid shrinks far more than the host, and in the simplest case, the differences shows up as an appeared bubble in the fluid at surface temperature. The homogenization temperature was measured by heating the sample until the bubble disappears (the fluid inclusion homogenizes) as viewed through microscope (Fig 2.4). The measurements of homogenization temperatures (Th) were acquired at heating rate of 20°C/min. Heatings for measurements of homogenization temperatures were taken before the freezing tests, which necessary to measure eutectic temperatures (Te) and ice melting temperatures (Tm). This sequence of measurements was performed to avoid an increase in the volume of the fluid inclusions cavities (stretching) due to ice crystallization and producing meaningless Th values.. 17.

(28) Figure 2.4 Serial photomicrographs of primary inclusion in calcite from location O19_2. During heating, the volume of the bubble decreases until the homogenization temperature; this inclusion would be said to “homogenization temperature in the liquid phase at 170°C”.. Three samples of open-filling calcites include one sample from type A (A42) and two samples from type Others (O06 and O19) from cores were chosen for fluid inclusion analysis. Three samples were chosen because (1) their carbon and oxygen isotope value have litter variation, (2) their stable isotope have bigger, middle and smaller value and (3) they have big crystal to make thin section (Fig 2.5).. 18.

(29) Figure 2.5 The carbon and oxygen isotope of sample A42, O06 and O19 were chosen for fluid inclusion analysis.. Procedure of making thin sections for fluid inclusion Step 1: Clean rock The core samples are cleaned thoroughly with water by toothbrush to wash away clay or dirt and then are dried at room temperature. Step 2: Cut the slab Mark a line on the rock with the sharper. At the location close to where powdered carbonates for stable isotope analysis were collected (Fig.2.6a). Step three: Cut the slab. 19.

(30) Using the slab saw cutter cut a slab from the rock along the line marked before. Then thin section (4 mm in thickness) is cut on a plane perpendicular to any planar fabric via saw cutter (Fig. 2.6b). Step 3: Grinding Take the slab, place it on the coarsest grinding disk with some water from faucet (Fig. 2.6c). Use only one finger on the back of the slab piece and grind with a medium to light pressure and move slab in circular route around disk. Grind it until all the saw marks or roughing marks are gone and slab becomes transparent (Fig. 2.6d).. Figure 2.6 Prepare thin section for fluid inclusion analysis 20.

(31) Thick slice specimens were polished ~ to 30nm roughness, then fluid inclusion is observed by using a THMS600 Heating and Freezing Microscope Stage Axio Scope A1 in National Taiwan Ocean University. The THMS600 has a temperature range from -196 to 600℃ with LNP95 (Fig 2.7).. Figure 2.7 THMS600 Heating and Freezing Microscope Stage Axio Scope A1. 2.4 Clumped-isotope analysis Carbonate lumped-isotope thermometry (Ghosh et al., 2006; Eiler, 2007) is a new tool for paleo-temperature reconstructions based on measurements of the degree of ordering of 13C and 18O into bonds with each other in lattices of carbonate minerals. The isotope exchange for carbon dioxide is shown in equation: 13. C16O2 + 12C18O16O ⇄ 13C18O16O + 12C16O2. (Eq.2). The Δ47 analysis is based on the tendency of heavy carbon and oxygen isotopes of calcium carbonate (CaCO3) to preferentially “clump” together, which is influenced by 21.

(32) the temperature at which the calcite precipitated (Schauble et al., (2006); Ghosh et al., (2006); Eiler, (2007). Clumped isotope geochemistry evaluates the amount of “clumping” found within gaseous CO2, which is the resultant product of acid digestion of calcite. The isotopologue of the CO2 gas that is evaluated for this study has an ionic mass of 47, which correlates to the 13C-18O-16O species. In addition, this analysis also measures masses 44, 45, and 46, which again calculates both the δ18O and the δ13C of the sample to give further verification of the stable isotope ratios (Table 2). In order to quantify such deviation, 47 is defined in the following equation: 𝑅47. 𝑅46. 𝑅45. 47= [(𝑅47∗ − 1) − (𝑅46∗ − 1) − (𝑅45∗-1)] ×1000‰]. (Eq.3). Whereas R47, R46, R45 refers to the measured and the calculated stochastic 47/44, 46/44, 45/44 ratio of the analyzed CO2. For CO2 (R = x/12C, or x/16O) with R45* = R13 + 2 R17. (Eq. 4). R46* = 2 R18 + 2 R13 R17 + (R17)2. (Eq. 5). R47* = 2 R13 R18 + 2 R17 R18 + R13 (R17)2. (Eq. 6). To prepare samples for clumped isotope measurements, A42 and O19 were selected for clumped-isotope composition to determine crystallization temperature and further evaluate fluid sources the crystallization in the Qatar Stable Isotope Laboratory at Imperial College London. 8-12 mg powders of each sample were took by micro miller with a 0.5 mm drill bit. Unlike the stable isotope analysis, the calcite for each of sample was combined and crushed into a single sample and reacted with 3.5% hydrogen peroxide for one day to remove organic materials and stirred for 5 min to produce CO2. This process was repeated five – seven days until no CO2 appears anymore. Then samples were dried in an oven at 55℃ overnight. Samples firstly were reacted with pure phosphoric acid at 90℃ water bath for 10 minutes. Then carbon dioxide and water were 22.

(33) collected in trap 1 by a liquid nitrogen trap for 20 minutes. By changing the liquid nitrogen trap to a -90℃ slush, made by liquid nitrogen and ethanol, the carbon dioxide was separated from water and then passed through a Porapak TM column at -35℃ for about 60 minutes in order to remove trace organic gases. After that, carbon dioxide was re-purified from water in trap 2 (Huang, 2017, p.12). Table 2 Abundances of isotoplogues of carbon dioxide assuming a random distribution of isotopes (Modified from Eiler et al., 2007). Mass. Isotopogue. Relative abundance. 44. 12. C16O16O. 98.40%. 45. 13. C16O16O. 1.11%. 12. C17O16O. 748 ppm. 12. C18O16O. 0.40%. 46. 47. 48. 49. 13. C O O. 84 ppm. 12. C17O17O. 0.142 ppm. 13. C18O16O. 44.4 ppm. 12. C18O17O. 1.50 ppm. 13. C17O17O. 1.60 ppb. 12. 17. 16. 18. 18. 3.96 ppm. 18. 17. C O O. 13. C O O. 16.8 ppb. 13. C18O18O. 44.5 ppb. Finally, the carbon dioxide collected in trap 3 was analyzed by using the Thermo Fisher MAT 253 gas source isotope ratio mass spectrometer, the CO2 gases were analyzed for masses 44 to 49 inclusive. And a software program named “Easotope” (John and Bowen, 2016) was used to perform all of the data processing. Procedures from Daëron et al., 2016 and Schaller et al. 2016 published the procedures was used for processing parameters to avoid 17O correction-problems. The measured mass 47 includes 23.

(34) not only mainly of. 13. C18O16O, but also minor of. 12. C17O16O and. 13. C17O17O. The 18O. values of calcite were calculated using the acid fractionation factors of Kim and O’Neil (1977) with the correction of Bohm et al., (2000). The raw ∆47 values were standardized by comparison to CO2 gases heated to achieve a nearly random distribution, and were corrected for temperature dependent fractionation during acid digestion. The standard error of the mean in the case of replicate analysis and the standard deviation are 0.02% for ∆47 0.05% for 18O, and 0.1% for 13C by Kluge et al., (2015). The standard errors of measured 13C and 18O values in our samples are less than 0.01‰. For clumped isotope analysis, the standard errors of 47 value are less than 0.02‰. The standard errors of clumped-derived temperature are less than 12℃.. 24.

(35) 25.

(36) Chapter 3. Results 3.1 Raman spectroscopy The Raman spectroscopy analyses in this study included 81 open-filling fracture samples (41 samples of type A, 12 samples of type B and 20 samples of type Others) and 8 marble lenses. The aim of Raman spectroscopy work is to determine what kind of minerals based on their reflectance spectra. Results of type A, type B and type Others are consistent with spectra of calcite. And, no any peak is related to aragonite (CaCO 3), dolomite (Ca, Mg(CO3)2) and magnesite (MgCO3). Fig. 3.1 illustrates the Raman spectra of calcite in type A, type B and type Others. The characteristic peak of calcite at 155, 282, 712 and 1086 cm 1. has been identified by compared with the reference minerals (Fig 2.2).. 26.

(37) Figure 3.1 Raman spectra of calcite of type A, type B and type Others (sample A42, B02, O19 are belonged to type A, type B and type Other, respectively). 27.

(38) Figure 3.2 Raman spectra of calcite of marble lenses. The Raman spectra of calcite of marble lenses were observed at the characteristics peaks of 152, 282, 711 and 1086 cm-1 (Fig 3.2) as the same with reference pattern of calcite (Fig 2.2). Also quartz and chlorite are identified in vein. Raman spectra of quartz with sample strong peaks at 128 cm-1 and at 464 cm-1 have been described by Fig 3.3a. Chlorites are found in the steep kink bands, it possess three predominant peaks at 198 cm-1, 546 cm-1 and 675 cm-1 shown in Fig. 3.3b.. 28.

(39) Figure 3.3 Photo and Raman spectra of (a) quartz and (b) chlorite. 3.2 Compositions of carbon & oxygen isotope analysis The 18O of open-filling calcites range from -2.16‰ to +20.58‰VSMOW, while 13C values range from -11.23‰ to -0.16‰VPDB (Appendix C). The oxygen and carbon isotope compositions of open-filling calcites and marble lenses are show in Fig 3.4. The oxygen isotope compositions of marble lenses have constant values with distributed carbon isotope. Type A and type Others have smaller 18O with bigger 13C. Type B has similar carbon isotope with varied oxygen isotope.. 29.

(40) Figure 3.4 The plot of stable isotopes of open-filling calcite and marble lenses from cores.. The carbon isotope values of carbonate powders range from -7.78‰ to -0.16‰ for type A (n=169); from -6.67‰ to -4.63‰ for type B (n=36); from -11.23‰ to -0.28‰ for type Others (n=86) and the 13C composition of marble lenses (n=49) range from -9.74‰ to -4.39‰ (Appendix C). The carbon isotope of type B has an average of ±‰VPDB (Table 3) which is almost constant with depth (Fig 3.5). The 13C of marble lenses ±‰VPDB (Table 3) also shows variation with depth. The 13C of fracture-filling carbonates do not have a trend with depth (Fig 3.5).. 30.

(41) Table 3 Statistics of carbon and oxygen isotope compositions form of open-filling calcites and marble lenses from meta-granite cores. Sample. 13C (‰VPDB). 18O (‰VSMOW). n. Type A. ±. ±. . Type B. ±. ±. . Type Others. ±. ±. . Marble lenses. ±. ±. . Figure 3.5 The carbon isotope values with depth.. 31.

(42) The oxygen isotope composition of calcite powders collected from meta-granite cores versus depth is shown in Fig 3.6. In detail, the 18O values of calcites range from 2.16‰ to 14.14‰VSMOW for type A, from -1.79‰ to 20.58‰VSMOW for type Others, from 4.44‰ to 19.23‰VSMOW for type B and from 10.18‰ to 11.53‰VSMOW for marble lenses (Appendix C). The oxygen compositions of marble lenses 18O (= 11.13 ± 0.38‰VSMOW) show little variation with depth compared with open-filling calcites (Table 3). The 18O of fracture-filling carbonates have no trend with depth (Fig 3.6).. Figure 3.6 The oxygen isotope values versus depth.. 32.

(43) Table 4 Statistics of carbon and oxygen isotope compositions of marbles and marble lenses in outcrops. Sample. 13C (‰VPDB). 18O (‰VSMOW). n. Marble lenses. ±. ±. . Marble (upstream). ±. ±. . Marble (downstream). ±. ±. . To investigate isotope signals of marbles and marble lenses in outcrops, 24 marbles were collected from both upstream and downstream of Hoping River and 2 marble lenses were collected in upstream. Their results are show in Table 4 the carbon and oxygen isotopes of marbles range from +0.23 to +4.28‰VPDB and from +10.36 to +24.28‰VSMOW, respectively (Appendix D). The 13C of marble in upstream has some variation from +0.23 to +3.86‰VPDB. Similarly, the carbon isotope values of marble in downstream oscillate between +2.20 and +4.28‰VPDB. Nevertheless, the oxygen isotope values of marble in downstream ±‰VSMOW are heavier than that of marble in upstream ±‰VSMOW(Table 4). Marbles in upstream and downstream have bigger 18O with smaller 13C. The carbon and oxygen isotopes of marble lenses in outcrops are similar to the oxygen and carbon isotope pattern of marble lenses in cores, the oxygen isotope of marble lenses in outcrops have constant values with distributed carbon isotope.. 33.

(44) Figure 3.7 The carbon and oxygen isotope pattern of marbles and marble lenses from outcrops.. 3.3 Fluid inclusion analysis Each inclusion we measured 30 measurements, inclusion sizes generally vary from20 to 50 µm (Fig 3.8). Fluid inclusion analysis was performed in type A (location A42_2) and type other (sample O06 and location O19_2). Fig 3.9 shows histograms of homogenization temperatures (Th) of the fluid inclusions within the calcite crystal from 164 – 231°C for sample A42 at 464.66m depth; from 106 – 305 ℃ for sample O06 at 217.05m depth and 160 – 211°C for sample O19 at 426.19m depth. The highest homogenization temperature was recorded at 305°C and lowest at 106°C. Although, the average homogenization temperature of location A42_2 (Th =190.76 ± 16.31°C) is higher 34.

(45) than that of sample O06 (Th =184.77 ± 48.12°C) and location O19_2 (Th =181.08 ± 16.79°C) (Table 5), error bar of sample O06 is overlapped with sample A42 and O19. Therefore, homogenization temperatures of three samples did not significantly change with depth (Fig 3.9), suggested that the local geothermal gradient was very low 30°C - 60°C/km during calcite precipitation (Lin, 2000, p.193).. Table 5 Statistics of homogenization temperatures (Th), temperature of first ice melting (Te) and last ice melting (Tm ) of sample A42; O19 and O06. No. Th (°C). Te (°C). Tm (°C). A42. ±16.31. ±3.35. ±0.27. O06. ±. ±. ±0.43. O19. ±16.79. ±. ±0.23. 35.

(46) Figure 3.8 Inclusion size of location A42_2 and O19_2.. 36.

(47) Figure 3.9 Homogenization temperature vs depth for location A42_2, O19_2 and O06. Error bars of Th is 1 standard deviation.. Freezing measurements for temperature of first ice melting (Te) and last ice melting (Tm) were made in aqueous saline inclusions. Te ranges from -49°C to -27°C for sample A42; from -40°C to -28°C for sample O19 and from -56°C to -32°C for sample O06. Tm for these fluid inclusions ranges from −1.02 °C to +0.3°C (Fig 3.10).. 37.

(48) 38.

(49) 3.4 Clumped isotope analysis The results of clumped isotopic compositions, 47 value and temperatures derived from sample A42 and O19 are shown in Table 6. The 47 value of sample A42 collected at a depth of 464 m is 0.415‰ and sample O19 collected at 426 m is 0.547‰. The calculated precipitation temperatures based on the 47-T calibration line from Kluge et al., (2015) are 209°C for A42 and 92°C for O19, respectively. As shown in Table 6, although the calculated temperatures of clumped-isotope analysis are increased with depth, it is very difficult to give reasonable interpretation by only two samples. Table 6 Clumped-isotope compositions and depth of A42 and O19 Experiment No. Depth (m). T°C. 13C (‰VPDB). 18O (‰VPDB). 18O (‰VSMOW). 47 (CDES). A42. 464.66. 209. -1.83. -29. 1.03. 0.415. O19. 426.19. 92. -6.11. -19.71. 10.6. 0.547. 39.

(50) Figure 3.11 The carbon isotope value of sample A42 and O19 verus depth for clumpedisotope.. The 13C values of clumped-isotope are -1.83‰ and -6.11‰ for location A42_2 and O19_2, respectively (Table 6). The carbon clumped-isotope values of location A42_2 and O19_2 are increased with depth (Fig 3.11). The oxygen clumped-isotope values of location A42_2 and O19_2 are 1.03‰ and 10.6‰VSMOW, respectively (Table 6). The 18O values are decreased with depth (Fig 3.12), opposite with the 13C pattern. Comparison with the carbon and oxygen isotope values, those of clumped-isotope of A42 and O19 have a trend with depth. In this study, because only two powders were analyzed for clumped-isotope analysis, it is very difficult to give reasonable interpretation. For the temperature result, the clumped temperature of sample A42 is similar with homogenization 40.

(51) temperature of fluid inclusion, but homogenization temperature of sample O19 is larger than clumped temperature of clumped-isotope.. Figure 3.12 The 18O value of sample A42 and O19 versus depth for clumped-isotope.. 41.

(52) Chapter 4. Discussion 4.1. 18O and 13C compositions of open-filling calcite In the section 2.2, we descripted that each sample was drilled three locations and each location was took three powders with different depths if possible (Fig 2.3). Thus, more or less nine calcite powders were collected per sample. As results, 18O values of openfilling calcites in all samples range from -2.16‰ to +20.58‰VSMOW and 13C values range from -11.23‰ to -0.16‰VPDB. In details, in fig 4.1, the carbon isotope of foliationoblique samples have variable value, however foliation-parallel samples have consistent value even considering measurement errors. For example, the carbon isotopes of sample A42 within location 1 are similar and values of location 2 are similar with that of location 3 (Fig 4.1a). However, the carbon isotope values of sample O19 are consistent with location 1&2 but different to location 3 (Fig 4.1b). The carbon isotope compositions of sample B13 have similar values for different depths (Fig 4.1c). Nevertheless, in Fig.3.6 the oxygen isotopes have inconstant values for all samples (no matter foliation -parallel and foliation oblique open-filling calcites). For instance, the oxygen isotope values of sample A42 range for +5.52 to +6.89‰VSMOW at location 1 (3 powders) and similar from -1.85 to 0.37‰VSMOW at location 2 and 3 (6 powders) (Fig 4.1e). For sample O19 (Fig 4.1f) and B13 (Fig 4.1g), 18O values fluctuate from +5.26 to +15.16‰VSMOW at all 3 locations (9 powders) per sample. Since the oxygen compositions of open-filling calcites for each sample were different, it suggested that the different oxygen isotopes of calcites might come from different 18O fluid, we will discuss more details in section 4.3.. 42.

(53) Figure 4.1 The carbon and oxygen isotope of open-filling calcites of sample A42, O19, B13 and VC11 for each location (1.1, 1.2, 1.3 ……..3.2, 3.3 are drilled references in fig 2.4).. 43.

(54) Figure 4.2 The carbon and oxygen of vein calcite with depth in TCDP work (Wang et al., 2010).. In order to know which cause might not be reasonable, we will check with previous work with similar situation first. In the previous study (Wang et al., 2010, p.252), the oxygen isotope values of fracture-filling carbonates ranged from 10‰ to 20‰VSMOW generally increased with depth. The carbonate isotope values of vein increased from -10‰ to -2‰VPDB at the depth from 400 to 1290m, and then decreased to -12.5‰ below 1290m (Fig. 4.2). They assumed that the fluid isotope balanced with the vein carbonate isotope, then they used to the equilibrium equation to calculate the oxygen of fluid by the equation of Õ Neil et al., (1969) based on the temperature inferred by the high local geothermal gradient obtained from the well-logging (22–25oC/km). Contrary to their work, the oxygen and carbon isotope of open-filling calcites in this study range from -11.23 to -0.16‰VBDP 44.

(55) and -2.16 to 20.58‰VSMOW, respectively (Figure 3.5 & 3.6). These results showed that the carbon and oxygen isotope do not have trend with depth, it probably did not be strongly influenced by geothermal gradient (gentle slope = -0.007) if geothermal gradient was constant (Fig 4.3). There will be more discussion for fluid origin in section 4.5.. Figure 4.3 Homogenization temperature (Th) versus depth of open-filling calcite showing a gentle slope.. 45.

(56) 4.2 The compositions of marble The stable isotopes of oxygen and carbon of marble lenses in core samples range from 10.18‰ to 11.93‰VSMOW and -9.74‰ to -4.17‰VPDB (Fig 3.4), respectively. To compare with these isotope compositions, we collected 26 marble samples from outcrop included 2 marble lenses. The 18O and 13C of marble lenses values in outcrop samples ranged from +10.08‰ to +10.68‰VSMOW and -2.2 to 0.79‰VPDB, respectively (Fig 4.4). As results, the oxygen isotopes of marble lenses in core samples are similar to the oxygen isotopes of marble lenses in outcrop samples. Nonetheless, the carbon isotopes of marble lenses have fluctuated value for core and outcrop samples.. Figure 4.4 The compositions of carbon and oxygen isotope in Hoping core and outcrop samples from previous study (Wang Lee and Teng, 1986) and our data.. 46.

(57) Analyses of marble in outcrop yielded that 18O values ranging from +17.52‰ to +24.28‰VSMOW for upstream samples and +15.67‰ to +23.01‰VSMOW for downstream samples (Fig 4.4). The 13C values in upstream and downstream samples range from +0.23‰ to 3.83‰VPDB and +2.31‰ to +4.28‰VPDB, respectively (Fig 4.4). A former research of marble outcrops in Hoping to Tailuko area (Wang Lee and Teng, 1986) showed that the 18O and 13C values ranged from +12.0‰ to +25.2‰VSMOW and +0.1‰ to 4.0‰VPDB, respectively, which is similar to our results. For investigating the possible causes of stable isotope composition from marble to marble lenses, the isotope compositions the boundary between marble and meta-granite (Fig 4.7). To calculate distance between marble and meta-granite along the profile, we plotted sample orientation by steoreonet, we determined mean pole of sample orientation (Fig 4.5). Then, the profile was drew perpendicular to mean strike (Fig 4.6). The horizontal created with the profile an angle Distance between marbles and meta-granites (l) is determined by projection of sample location onto the profile, which is parallel to strike orientation. These results were listed in Appendix B. . 47.

(58) Figure 4.5 Mean pole of sample orientation in upstream and downstream. 48.

(59) Figure 4.6 Projection of marble and meta-granite in outcrops.. 49.

(60) Figure 4.7 The carbon and oxygen isotope with distance relationship between marble and meta-granite in outcrops. We assumed that the 18O fluid values of marble lenses are equilibrium with 18O fluid values of metamorphic waters, therefore the temperature was calculated based on Eq.7. The inferred temperature of marble lenses range from 137.19°C to 11516.68°C (Appendix G). The clumped isotope temperature of marble collected from the Backbone Range of Taiwan ranges from 95°C to 329°C, (Lasker et al., 2016), the clumped isotope temperature of calcite veins in Chingshui area range from 136°C to 264°C (Lu et al., 2017), the temperature of calcite hosted in Carrara marbles is 250°C (Vaselli, et al., 2012) and the clumped-isotope of carbonate veins from the SAFOD ranges from 110°C to 115°C (Luetkemeyer et al., 2016) (yellow square in fig. 4.8). Based on previous work, the higher temperature from 480°C to 1050°C will made crystal broken and lower temperature below 95°C, inclusion size is very small. In next work, we expected that the temperature from higher than 95°C and less than 480°C. 50.

(61) Figure 4.8 The 18O fluid of marble lenses and expected temperature.. 51.

(62) Figure 4.9 The 13C and 18O values of fresh-water carbonates and marine limestones by Keith and Weber (1964). The comparison between the carbon and oxygen isotopes of open-filling calcites and marbles in this study and marbles in previous works.. Fig 4.9 shows the 13C and 18O values from marine limestone (cyan square ) and fresh-water carbonates (orange square) based on Kieth and Weber, (1964) (table 1 & 2, p. 1795-1796). The oxygen isotope value of fresh-water carbonate and marine limestones ranges from 20.3 to 26.3‰VSMOW and 20.8 to 29.6‰VSMOW, respectively. The carbon isotope value of marine limestone and freshwater carbonates ranged from -0.07‰ to 1.96‰VPDB and -6.64‰ to -2.24‰VPDB, respectively. The distribution the 13C and 18O values of marbles from previous study (Lee et al., 1986, table 1, p.37) range from 0.14 to 3.58‰VPDB and from 14.38 to 25.16‰VSMOW, respectively (purple square in Fig 52.

(63) 4.9). These results were overlapped with most of marbles in upstream and downstream of Hoping area. Based on the conclusions of Keith and Weber, (1964), the isotope composition of oxygen and/or carbon of calcite can be changed due to exchange between calcite and fluid. Although all the carbon composition of marble in upstream lie within the region indicative of a marine limestone, a substantial number of the oxygen isotope values do not conform to this trend (pale yellow in Fig 4.9). The carbon isotope compositions clearly demonstrate that the marble studied are probably of marine origin.. 53.

(64) 4.3 Calculated δ18O fluid. Figure 4.10 Summary plot of stable isotopes and temperatures of sample A42, O06 and O19 and clumped isotope temperature (sample A42_2 and O19_2 are the location where were made thin sections for fluid inclusion and clumped isotope analysis).. After resulting δ18O value of open-filling calcites in section 3.2 and related forming temperature in section 3.3 and 3.4, the δ18O of fluid will be evaluated in this section. Here, the δ18O fluid was calculated using the calcite-water oxygen isotope fractionation equation (O’Neil et.al., 1969, p.5547) (Eq.7): T(℃) = √𝛿18 𝑂. 2.78×106. 𝑐𝑎𝑙 −𝛿. 18 𝑂 𝑓𝑙𝑢𝑖𝑑 +2.89. − 273.15. (Eq.7). 54.

(65) Cause of variations in δ18O fluid can either be from changes in temperatures, fluid composition, or both of them (Zheng and Hoefs, 1993). 30 measurements of homogenization temperatures were conducted for location A42_2 and O19_2 from one thin section and 18 measurements for O06 from 5 thin sections. The average homogenization temperature of sample A42, O06 and O19 is 191±16℃, 187±46℃ and 185±17℃, respectively (Fig 4.9). The oxygen fluid values were calculated based on Eq.7, because temperature measurements were not conducted on all location for isotope analysis, the assumption that temperature was the same for all isotope compositions of open-filling calcites were made. In details, 9 isotope compositions of sample A42 (blue in Fig 4.10) and 30 homogenization measurements at location A42_2 were used to calculate δ18O fluid (red triangle in Fig 4.11). Total, 270 values δ18O fluid at location A42_2 were calculated. The δ18O fluid value at location A42_2 range from -13.75 to -10.22‰VSMOW (red bar in Fig 4.12a); from -6.27 to -1.63‰ and -13.50 to -8.89‰VSMOW at location A42_1 and A42_3, respectively (black and red bar in Fig 4.12a). Fig 4.10 show that location A42_1 have bigger δ18O and smaller δ13C than location A42_2 and location A42_3 and the calculated oxygen fluid values at location A42_2 and A42_3 is similar, but different with that of A42_1, it suggested that the δ18O fluid at location A42_1 is not reliable. For sample O06, it was made five thin sections from different location of the whole sample. The δ18O fluid was calculated by 6 oxygen isotope values time with 18 homogenization temperatures. Results show that the δ18O fluid value of sample O06 range from -12.08 to -0.53‰ (Fig 4.12b). For sample O06, the calculated oxygen fluid range from -12.08 to -0.53‰VSMOW, from -13.54 to -2.01‰VSMOW and from -11.93 to -0.91‰VSMOW at location O06_1, O06_2 and O06_3, respectively. The δ18O fluid values of whole sample O06 are overlapped together. For sample O19, the δ18O fluid values also calculated similar to sample A42 with 55.

(66) 30 homogenization temperatures and 9 oxygen isotope values. The δ18O fluid of location O19_2 range from -6.67 to 4.09‰ (blue bar in Fig 4.12b); from -3.86 to 6.24‰ and from 6.67 to 0.8‰ at location O19_1 and O19_3, respectively (black and red bar in Fig 4.12b). Two oxygen isotope powders of A42_2 and O19_2 are used for clumped-isotope analysis. The δ18O of location A42_2 and O19_2 are 1.03‰ and 10.6‰VSMOW, respectively. The clumped isotope temperatures of open-filling calcites of A42 and O19 powders are 209 and 92℃, respectively (Fig 4.12). Based on Eq.7, the δ18O fluid were calculated by the oxygen isotope values with clumped isotopes are -8.04‰ and -7.36‰ for location A42_2 and O19_2, respectively (red line in Fig 4.12 a & c).. 56.

(67) Figure 4.11 The calculated oxygen isotope fluid of open-filling calcites vs Th. Black, blue and red rectangle represents the 18O fluid at location 1, location 2 and location 3, respectively. 57.

(68) Figure 4.12 The calculated oxygen isotope fluid of open-filling calcites. Black, blue and red rectangle represents the 18O fluid at location 1, location 2 and location 3, respectively. Red line represents the 18O fluid of clumped-isotope. 58.

(69) 4.4 Meteoric water The meteoric water have a wide range of oxygen and hydrogen isotope, like meteoric waters come from all areas in the world (Craig, 1961). In order to evaluate whether fluid of open-filling calcites come from meteoric water, we plotted δ18O with elevation range from 0m to 4000m in Fig.4.7 following previous work (Shieh, et.al, 1983, p.130): For h ≦ 760m: δ18O = -0.0062h - 6.1‰. (Eq.8). For h ≧ 760m: δ18O = -0.0012h - 9.6‰. (Eq. 9). Where h is altitude in meters. Table 7. The δ18O values in Taiwan at the different elevations base on previous work (Shieh, 1983, p.130). Elevation (m). δ18O(‰VSMOW). Elevation (m). δ18O(‰VSMOW). 4000. -14.4. 400. -8.58. 3000. -13.2. 300. -7.96. 2000. -12.0. 200. -7.34. 1000. -10.8. 100. -6.72. 500. -9.2. 0. -6.1. The δ18O values of meteoric water in Taiwan were calculated based on Eq.8 and Eq.9 at the elevations ranged from 0m to 4000m height (Table 7). The oxygen isotope of local meteoric water is lighter with high elevations (Fig 4.13).. 59.

(70) Figure 4.13 Plot of 18O value with elevation in Taiwan. These values were calculated based on previous study by Shieh, 1983.. 57.6mg crystal CaCO3 of location O19_2 was used the oxygen and hydrogen of fluid inclusion analysis (Uemura et al., 2015). The 18O and D compositions are -9.6‰ and -58.6‰, respectively (Figure 4.13).. This result covered meteoric water at 564m. elevation. The calculated temperature is 57°C, 114°C and 72°C based on Eq.7 with 18O calcite value from stable isotope analysis for location O19_2 (3 location).. 60.

(71) Figure 4.14 Plot of D and 18O compositions of location O19_2. As results in section 4.3, the oxygen isotope fluid at location A42_2 (blue bar in Fig 4.15a) is as the same as that of A42_3 (red bar Fig 4.15a), range from -13.75‰ to -8.4‰. These values show that the 18O values of fluid at location A42_2 and location A42_3 lie in a wide range of elevations from 3000m to 0m. The average of calculated oxygen isotope fluid at location A42_2 is -11.76 ± 0.91‰VSMOW, it shows that the 18O values of fluid at location A42_2 is at elevation about 2000m. In much the same way with location A42_2, the average of calculated fluid at location A42_3 is -10.91 ± 0.91‰VSMOW, it shows that the 18O values of fluid of location A42_2 is at elevation about 1000m. However, the 18O fluid at location A42_1 (black bar in Fig 4.15a) range from -6.1‰ to -1.13‰ is bigger than that of location A42_2 and A42_3. Consequently, they do not lie in these line, suggesting that the fluid of A42_1 calcite did not come from meteoric water. Similarly, for sample 61.

(72) O06, the calculated oxygen values of fluid of location O06_1, O06_2 and O06_ 3 (black, blue and red bar in Fig 4.15b) are similar, range from -13.54 to -0.54‰. Figure 4.8b shows that the calculated oxygen values of a part of location O06_1 and O06_2 lie in a wide range of elevation from 0 to 2000m and that of location O06_ 3 lie in elevation from 0 to 3000m. The calculated oxygen isotope of fluid of location O19_3 (red bar in Fig 4.15c) was covered that of local meteoric water at elevation from 0 to 100m high. However, the 18O values of fluid of location O19_1 and O19_2 (blue & red bar in Fig 4.15c) is heavier than the 18O values of meteoric water in Taiwan with elevation range from 0 to 3000m (Fig 4.15c). It indicates that the calculated oxygen fluid did not come from meteoric water. For clumped isotope analysis, the 18O values of fluid of sample A42 and O19 were showed in section 4.3, the computed δ18O fluid of sample A42 is -8.04‰VSMOW and that of sample O19 is -7.36‰VSMOW (red line in Fig 4.15a &c). As a consequence, the oxygen isotope of fluid of A42 and O19 are overlapped with δ18O values of the meteoric water in drainage divides of 300m to 400m and 100m to 200m, respectively.. 62.

(73) Figure 4.15 The O fluid of sample A42, O06 and O19 vs different elevation in Taiwan. Black, blue and red rectangle represents location 1, location 2 and location 3, respectively. 63.

(74) 4.5 Fluid sources In figure 4.16a (red & blue rectangle), it shows that the δ18O fluid of location A42_2 and A42_3 were covered that of meteoric water at elevation from 500 to 3000m and 400 to 3000m, respectively. The δ18O fluid of location A42_2 and A42_3 implied that meteoric water could play an important role of forming open-filling calcites. Similar to the δ18O fluid of sample A42, those of sample O06 are within the range of meteoric water (Fig 4.16b). In details, the calculated δ18O fluid of location O06_1, O06_2 and O06_3 (black, red & blue rectangle in Fig 4.16b, respectively) were covered that of local meteoric water at different altitudes from 3000m to 0m. The δ18O fluid of location O06_1 is similar with that of location O06_2, which is covered in meteoric water source from 0 to approximately 2000m height, while that of location O06_3 is covered from 0 to 3000m height. The calculated δ18O fluid of location O06_1, O06_2 and O06_3 imply that meteoric water might play an important role of forming open-filling calcites. However, the oxygen isotopes of the shaded area in Fig 4.11b are below sea level and it is located at the range between meteoric and metamorphic or magmatic waters. It could not be the single component of meteoric waters, anymore. So, it might indicate a mixture sources (Fig 4.16b). The δ18O fluid at location O19_3 (red rectangle in Fig 4.16c) are located at the area in meteoric water line at elevation from 0 to 100m. Fig 4.11 shows that the δ18O compositions of magmatic waters range from 5.5 to +9.5‰VSMOW (cyan bar in Fig 4.16 Sheppard., 1986, p.171). The δ18O compositions of metamorphic waters range from 3 to +20‰VSMOW (green bar in Fig 4.16). Compared with the δ18O fluid at location O19_1 (black rectangle in Fig 4.16c) is as same as O19_2 (blue rectangle in Fig 4.16c), and both were covered both ranges of the magmatic waters, and the range of metamorphic waters. This suggests that the mineralizing fluids were mixed meteoric water with (1) magmatic 64.

(75) sources, (2) metamorphic waters or (3) mixing between magmatic and metamorphic waters (Fig 4.16c). In previous study (Lu et al, 2017, p.5), the δ18O fluid of thermal fluid, which precipitated the calcite scaling in well IC-13 in the Chingshui geothermal area, ranges from -6.5 to -5.1‰. Their works indicated that their data was covered with local meteoric water, which range from -11 to 0‰ (Liu et al., 1990). The average δ18O fluid values of sample O06 is -6.26 ± 2.62‰ as the result of the δ18O fluid of calcite in Chingshui area. Therefore, the δ18O fluid of sample O06 might also come from local meteoric water origin. On the other hand, the δ18O fluid precipitating calcite veins in and near surface outcrops of fault zones at Chingshui geothermal area were calculated by Eq1 range from -1.0 ± 1.6‰VSMOW to 10.0 ± 1.3‰VSMOW (Lu et al, 2017, p.7). They suggested that these oxygen isotopes might originate from two parts: one came from meteoric water with the smaller 18O compositions, the other might come from either magmatic or metamorphic fluids with bigger 18O compositions. The δ18O fluid at location O19_3 (red rectangle in Fig 4.16c) range from -3.75±0.94‰ is same as results with smaller 18O compositions. Therefore, these data might come from local meteoric water. While, δ18O fluid of location O19_1 and O19_2 (black & blue rectangle in Fig 4.16c, respectively) range from 0.22±0.94‰VSMOW. The results indicated that the δ18O fluid of location O19_1 and O19_2 may be generated by either magmatic or metamorphic processes. A previous study (Laskar et al., 2016, p.4) analyzed marbled collected close to boundary between marble and meta-granite in Hoping area. The clumped temperature of sample 910726-3C/3E ranged from 169°C to 256°C and from 95°C to 166°C. The oxygen isotope composition of fluid in their study was calculated based on Eq.7 (O’Neil et al., 65.

(76) 1969), which ranges from -1.9 to 10.7‰. The positive and high values showed that the fluid sources have different origins and/ or resulted from extensive interaction with rocks during penetration process while the fluid phase originated from local meteoric water with negative the 18O fluid (Laskar et al., 2016, p.3). In comparison, the clumped temperature of sample A42 and O19 in this study is 209°C and 92°C, respectively. The clumped temperature of sample A42 is similar with that of marbles of sample 910726-3C/3E and the temperature of sample O19 is smaller than that of marbles of sample 910726-3C/3E. The computed oxygen isotope values of A42 and O19 is -8.04‰ and -7.36‰VSMOW, respectively. They inferred that the 18O fluid of sample A42 and O19 come from meteoric water origin. The depth of penetration is estimated at least 3-6 km based on geothermal gradient of 30–60°C/km (Lin, 2000, p.193).. 66.

(77) Figure 4.16 The oxygen isotope and the calculated oxygen of fluid a) Sample A42, b) Sample O06, and c) Sample O19. Black, blue and red rectangle represents location 1, location 2 and location 3, respectively. Isotopic compositions and fields for metamorphic waters and magmatic waters are based on Sheppard, 1986.. 67.

(78) Chapter 5. Conclusion In this study, Raman spectroscopy, carbon and oxygen isotope, fluid inclusion and clumped-isotope analysis were used to evaluate the possible fluid source of open-filling minerals within meta-granites in Hoping area, eastern Taiwan. Identification of carbonate minerals is conducted by Raman spectroscopy. Calcite of typical bands at 152, 282, 711 and 1086 cm-1 is identified in all open-filling carbonates. Expect calcite, other carbonates did not find in any of open-filling minerals. The carbon and oxygen compositions of open-filling calcites and marble lenses in cores and marbles and marble lenses on outcrops were analyzed, and the oxygen isotope of fluid were calculated to examine fluid sources based on stable isotope and temperatures of calcite form analyses of fluid inclusion and clumped-isotope. The carbon and oxygen isotope analyses of open-filling calcites collected from meta-granites cores do not have clear trend with depth. It indicated that open-filling calcite in this study probably did not be influenced by geothermal gradient. The oxygen isotopes have inconstant values for all samples, no matter foliation parallel and foliation-oblique open-filling calcites. It suggested that the oxygen compositions of fluid were dissimilar, suggesting that 18O of fluid might be different. For open-filling fracture calcites different trends between the oxygen and carbon isotopes are found. Foliation oblique open filling calcites have smaller 18O with bigger 13C. For foliation paralleled open-filling, calcite has similar carbon isotope with varied oxygen isotope. The average homogenization temperature of A42, O06 and O19 is 191°C, 185°C and 181°C, respectively. The calculated 𝛿18O fluid values at location A42_2 and A42_3 ranges from -13.33 to -8.89‰VSMOW and that of location O06_1, O06_2 and O06_3 are 68.

(79) similar (-6.26 ± 2.62‰VSMOW). These results indicated that the origin of fluid possibly came from local meteoric waters with different elevations from 0 to 4000m. It also inferred that meteoric water might play an important role of forming open-filling calcites. However, the computed 18O values of fluid of location O19_1 may be generated by either magmatic or metamorphic processes. The oxygen of clumped-isotope value of location A42_2 and O19_2 are 1.03‰ and 10.6‰VSMOW with clumped temperature is 209°C and 92°C, respectively. The computed fluid oxygen isotope values of A42 and O19 is -8.04‰ and 7.36‰VSMOW, respectively based on the oxygen isotope of calcite and temperature of clumped isotope. They inferred that the equilibrium 18O compositions come from meteoric water origin at elevation from 200m to 300m elevation. On the contrary to foliation-paralleled open-filling calcites, oxygen isotope of marble lenses in cores within meta-granites oxygen isotope have constant values with distributed carbon isotope. As results from stable isotopes, the isotope pattern of marble lenses in outcrops are similar with the oxygen of marble lenses in cores. The carbon and oxygen isotope values of marbles collected in upstream of Hoping area conclude that the marbles in this study area are probably of marine limestone origin. And the oxygen isotope values of the marbles close to the meta-granite may have been lowered during metamorphism.. 69.

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