E-ISSN : 2541-5794 P-ISSN :2503-216X Journal of Geoscience, Engineering, Environment, and Technology Vol 02 No 03 2017 Zar A.T. et al./ JGEET Vol 02 No 03/2017 191 Geochemical Characteristics of Metamorphic Rock-Hosted Gold Deposit At Onzon-Kanbani Area, Central Myanmar Aung Tay Zar 1,3, *, I Wayan Warmada 1 , Lucas Donny Setijadji 1 , Koichiro Watanabe 2 1 Department of Geological Engineering, Faculty of Engineering, Gadjah Mada University, Yogyakarta, Indonesia 2 Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan 3 Department of Geology, Pyay University, Pyay, Myanmar * Corresponding author : aungtayzar99@gmail.com Tel.:+62-81-329-747-974 Received: June 16, 2017. Revised : July 1, 2017, Accepted: Aug 20, 2017, Published: 1 Sept 2017 DOI : 10.24273/jgeet.2017.2.3.410 Abstract Onzon-Kabani area is located on the western border of generally N-S trending Mogoke Metamorphic Belt. Many artisanal and small-scale gold mines were noted sincelast three decades. Gold mineralization is mainly hosted in marble and occasionally observed in gneiss.Host rocks chemistry is mainly controlled by hydrothermal activities and regional metamorphism. The compatible elements of host rocks are relatively more mobile than incompatible elements during alteration and deformation. Variety of plutonic rocks such as leucogranite, syenite and biotite granite are intruded into older metamorphic rocks. In ACF diagram, leucogranite and syenite are placed in S-type granite field and biotite granite occupied in I-type granite field. Mineralization is observed as fracture filling vein and less amount of disseminated nature in marble unit. Mineralogically, gold areassociated with other base metal such as pyrite, galena, sphalerite, and chalcopyrite. Hydrothermal alteration halos are developed as a narrow zone in the peripheral of hydrothermal conduits from proximal to distal; 1) silicic, 2) sericite-illite, and 3) propylitic alteration. In place, silicic altered zone is rich in SiO2, Al2O3, and K2O. Moreover, concentrations of S, Cu, Zn, and Pb are more than any other alteration zones. The CaO is gradually increase to least altered zone where wt% of loss of ignition (LOI)also increase significantly to least-altered samples (marble). Some fluid boiling characteristics of vein textures and fluid inclusion petrography are also observed in hydrothermal system of research area. The homogenization temperature (Th) of quartz vein samples are 159°C to 315°C and salinity are 0.88 to 12.51 wt% of NaCl equivalent. This research focused to describe the geochemical characteristics of metamorphic rock-hosted gold deposit in Onzon-Kanbani area. Keywords: Mogok Metamorphic Belt, Fracture filling vein, Hydrothermal alteration, Fluid boiling 1. Introduction Gold and associated base metal mineralization at Onzon-Kanbani areais located in Thabeikkyin Township, Mandalay region, central Myanmar. This area is west 85km faraway from well known Mogok Township (ruby land), Myanmar. Small scale local gold rush and abundant artisanal working were started since last thirty years ago. This area is alsoa part of Mogok Metamorphic Belt(Searle and Haq, 1964)which famous for their precious and semi- precious gem stones production and distinct geological feature. Mineralization is mostly hosted in marble unit and occasionally in gneiss.It is observed as fracture filling veins and minor disseminated nature in marble. Generally, gold mineralization in Mogok Metamorphic Belt is inferred as orogenic gold (Mitchell et al., 2004) but locally epithermal and skarn gold mineralization are also spread along this belt (Myint et al., 2014). The main objective of this paper writing is not onlyto describethe geochemical characteristics of metamorphic rock-hosted gold deposit but also to understand the deposit genesis of research area. 2. Methods of study Totally, fifty ofthin and polished sections of altered rocks and ore sampleswere conducted for mineralogical study by optical microscope and confirmed again by scanning electron microscopy with energy-dispersive X-ray (SEM-EDX). Additionally, X-ray Diffraction (XRD) analysis for the hydrothermal alteration minerals that were done for both bulk rock (random powder) and clay fraction. Major and trace elements analyses were carried out on representative samples using XRF and inductively coupled plasma optical emission spectroscopy (ICP-OES).Moreover, quartz samples were collected from mineralization veins to conduct fluid inclusion study. Double polished quartz wafers were prepared for these quartz veins where the thickness of wafers varied between 150 and 300µm. Microthermometric measurements were done using Linkam THMSG600 combined mailto:aungtayzar99@gmail.com 192 Zar A.T. et al./ JGEET Vol 02 No 03/2017 heating and freezing stage, attached to Nikon petrographic microscope with Axiovision software. All of these laboratory analyses were made in Department of Earth Resource Engineering, Mineral Resource lab, Kyushu University, Japan. 3. Regional geologic setting Myanmar is tectonically complex region and composed with micro plates such as Sibumasu, West Burma, and India. Along a tectonic history is built by repeatedly occurring subduction, accretion and collision events. These events chiseled the geological landform and metallogenic provinces in Myanmar. Traditionally, the territory of Myanmar is subdivided into (1) the India plate to the west, (2) Burma microplate (West Burma) in the central part and (3) Shan- Mogok Metamorphic Belt is one of the distinct geological and metallogenic province in Myanmar and located between Central low-land (West Burma) and Shan-Thai block (Sibumasu). It is believed that southern continuation of Himalaya (Searle and Haq, 1964)and formed by either collision (Mitchell, 1979) or strike-slip movement (Metcalfe, 2009). In this place, well-known right lateral strike-slip fault, Sagaing Fault (Swe, 1972)is served as awestern boundary. Alternatively, thestructural configuration of this area is closely related to this fault.Mogok Metamorphic Belt is composed of Paleozoic to Mesozoic meta-carbonate rocks andmetapelite where avariety of Cretaceous- Palaeogene plutonic igneous rocks(Barley et al., 2003; Mitchell, 1979; Mitchell et al., 2012)are intruded to older rocks. East of this belt, Shan Plateau (Sibumasu) is a topographic high with anaverage elevation of about 1000m and mainly composed of a series of Ordovician-Triassic carbonate rocks and continental sedimentary rocks (Jurassic?). The western margin of Mogok Metamorphic Belt is juxtaposed with Central low- land (West Burma) which is filled by Eocene to Plio- Quaternary sediments. 4. Geology of Onzon-Kanbani area Onzon-Kanbani area is a part of Mogok Metamorphic Belt. Therefore, mainly composed with metamorphic and igneous rocks which are exposed with differing areal coverage (Fig.2).Metamorphic rocks of research area such as avariety of marbles, calc-silicate rocks and gneiss are widely distributed in eastern and western part. The age of the protolith of metasedimentary was originally considered Precambrian (Bender, 1983), but Permian fossils in marble near Kyaukse (Thein and Win, 1969)indicate that Carboniferous to Triassic ageis more likely. Alternatively, igneous units are generally covered the middle part of the research area and found as fitful. The older metamorphic rocks are intruded by granite and syenite. The main igneous intrusion of the research area is biotite granite Metamorphic Belt ranged that magmatism of leucogranite and syenite melt took place in Eocene time during the regional metamorphism and then Kabaing granite intruded the country rocks of the study area in Miocene after regional metamorphism (Barley et al., 2003). Fig.1. Map showing geologic setting of Mogok Metamorphic Belt and its environ. Modify after(Barley et al., 2003) Zar A.T. et al./ JGEET Vol 02 No 03/2017 193 5. Petrography The dominant metamorphic rocks in Onzon- Kanbani area which is composed of meta-carbonate rocks (marbles and calc-silicate rock) and biotite gneiss. Heterogeneous igneous intrusions are observed the middle part of the area where diopside calc-silicate rock occur along the margin of igneous intrusions (Fig. 2). Marble unit appears white (fresh) and dark gray to pale greenish (weathered) in color. The foliated nature also occurs in some marbles (thin foliated marble and diopside marble) and calc-silicate rock. Gneiss unit is medium-crystalline, banded and gneissose with finer and coarser portion. Weathered color light grayand dark gray of fresh surface indicate that abundance of biotite and hornblende in gneiss. In igneous rocks, leucogranite and syenite are observed as small intrusive bodies intruded to marble units. Light to pinkish color appearance of outcrops arecharacteristic feature. Biotite granite is a one of important plutonic rock in research area. It has dark grey to yellowish color weathered surface and light grey offresh surface. The exfoliation nature is common textural feature. Microscopic observation shows a variety of minerals in marble and gneiss. In marble unit, diopside, phlogopite, calcite are main constituents whereas biotite, plagioclase and quartz are dominant in gneiss. Some of the minerals are believed that the products of regional metamorphism related with India-Asia collision. In syenite and leucogranite, felsic color minerals are mainly observed such as quartz, plagioclase, muscovite and nepheline. The common minerals of biotite granite are quartz, biotite, plagioclase and orthoclase. Fig. 2. Simplify geological map of research area with sample location. After Myint Lwin Thein (Thein et al., 1990) 6. Petrochemistry 6.1 Petrochemistry of host rocks The major and trace elements composition of host rocks (marble and gneiss) are given in Table-1. The chemical characteristics of host rocks are mainly controlled by regional metamorphismas well ashydrothermal activities. Basically, host rock marble is rich in CaO and MgO whereas thenotable amount of Al2O3 content showed that their mica content in marble. Alternatively, gneiss samples are a high content of SiO2 range from 45.983 to 49.672wt% where CaO is not too much between 9.254 to 11.301wt.%.In order to evaluate the compositional change which accompanies deformation and hydrothermal alteration, the concentrations of elements of interest are compared to those of immobile such as Zirconium. Typically, Zr is used as animmobile and incompatible element during hydrothermal alteration due to thevery high ionic radius where SiO2 and some of themajor oxide elements cannot use because of alteration effect. In the case of chemically incompatible element Zr versus compatible elements (Zn and Cr) regression lines which are considered to be mobile with each other in the marble and gneiss units during alteration and deformation. The compatible elements (Zn and Cr) are more mobile relative to Zr (incompatible) during deformation and hydrothermal alteration as shown by their poor correlations in Figure (Fig. 3). But in thecorrelation between both of incompatible elements, Zr vs (Sr and Ba) are considered to be immobile with each other in the marbles and gneiss unit while impacting alteration and deformation. The interelement correlation among the trace elements is significant which is consistent with their similar geochemical behavior. 194 Zar A.T. et al./ JGEET Vol 02 No 03/2017 6.2 Petrochemistry of intrusive igneous rocks The chemical composition of plutonic igneous rocks at Onzon-Kanbani area was observed to identify the type of igneous rocks and their tectonic setting. The care during sampling was on fresh rocks, it intended to avoid metasomatic changes during hydrothermal alteration. Results of major and trace elements of plutonic igneous rocks from Onzon-Kabani area are summarized in Table-2. Major element data and converted normative data (CIPW Norm) of plutonic rocks are used to plot on total alkalis-silica (TAS) diagram as well as albite- anorthite-orthoclase triangular diagram to classify these plutonic rocks. According to total alkalis-silica (TAS) discrimination diagram, the plutonic rocks of study area belong to acidic to intermediate rocks of granite and syenite (Fig. 4). The Ab-An-Or discrimination diagram is intended to avoid the criticism that wt.% oxide data do not faithfully and to confirm plutonic rock classification. This triangular diagram also showed that plutonic rocks of research area are granite, syenite, and tonalite (Fig. 4) respectively. All of these samples are pointed out as calc-alkaline type by AFM diagram (Fig. 4). Moreover, ACFdiagram also showed that most plutonic rocks of Onzon- - peraluminous except two samples of biotite granite which fall in - metaluminous. Y versus Nb and Rb versus Y+Nb diagrams (Pearce et al., 1984)were used to discriminate the tectonic environment of plutonic rocks in Onzon- Kanbani area. These diagrams showed that most of plutonic rocks are in syn-collisional granite (syn- COLG) and within plate granite (WPG) except some samples which are placed in volcanic arc granite (VGA) (Fig. 5). Table 1. Major and trace element composition of least-altered -Kanbani area Sample ID ZYK1 (MB) ZYK2 (MB) ZYK3 (MB) GS (MB) GS-8 (MB) GK (MB) TMA6 (MB) SZYK3 (MB) GY-1 (GN) GY-9 (GN) ZYK15 (GN) SiO2 (%) 2.321 8.123 6.916 5.735 2.259 8.731 10.27 9 7.786 45.98 3 49.67 2 46.304 TiO2 0.007 0.166 0.132 0.182 0.009 0.117 0.102 0.194 1.249 1.482 1.385 Al2O3 0.41 1.912 1.856 1.888 0.36 1.826 1.933 2.449 16.73 9 15.37 3 16.274 FeO 0.615 0.697 1.035 0.772 0.607 0.546 1.183 0.727 7.356 8.882 8.238 MnO 0.029 0.031 0.033 0.035 0.037 0.023 0.102 0.03 0.136 0.199 0.173 MgO 6.222 1.982 1.881 1.996 6.626 1.489 2.222 1.765 6.416 7.676 7.029 CaO 48.32 6 54.13 4 52.18 6 52.19 9 46.12 4 50.52 7 48.52 7 50.583 11.30 1 9.254 11.088 Na2O 0.291 0.005 0.045 0.006 0.383 0.015 0.003 0.063 1.411 1.726 1.669 K2O 0.378 0.801 0.59 0.58 0.019 0.861 0.358 0.9 2.317 2.798 2.25 P2O5 0.003 0.012 0.01 0.011 0.001 0.013 0.006 0.012 0.738 0.224 0.833 LOI 40.01 31.18 34.73 36.42 43.5 35.69 35.12 35.37 3.82 2.13 2.68 Total 98.61 2 99.04 3 99.41 4 99.82 4 99.92 5 99.83 8 99.83 5 99.879 97.46 6 99.41 6 97.923 V(ppm) 5 9 13 22 3 12 15 13 298 334 329 Cr 36 41 39 45 38 42 33 38 42 140 55 Co 11 18 22 24 10 21 23 16 32 33 35 Ni 21 25 24 27 19 22 26 28 48 74 51 Cu 6 8 9 11 5 9 15 7 50 25 47 Zn 21 29 31 33 18 39 66 38 113 148 124 Pb 96 5 7 1 112 n.d 74 7 15 10 1 As n.d 7 4 7 n.d 10 6 5 13 6 16 Mo 12 15 14 14 9 17 14 17 48 14 41 Sr 181 481 477 473 179 473 495 548 3822 542 3324 Ba n.d 81 105 84 n.d 180 24 115 1692 425 1532 Y 6 7 11 9 4 10 6 14 20 48 21 Zr 1 21 34 17 n.d 66 26 37 53 68 36 Nb n.d 2 1 1 n.d 2 1 2 3 13 4 Rb 4 38 30 29 3 36 18 53 57 182 56 Note: Total Fe content expressed as FeO(tot); n.d= below detection limit; major element and LOI are weight percent; trace elements are in ppm Zar A.T. et al./ JGEET Vol 02 No 03/2017 195 Fig..3 Binary variation diagrams in Cr, Zn, Sr and Ba (all in ppm) for host rocks of Onzon-Kabani area whereas Zn and Cr are compatible elements, and Zr, Srand Ba are incompatible elements Fig.4. (a) Classification diagrams of plutonic rocks using total alkaline versus SiO2(Middlemost, 1994), and (b) Ternary plot diagram in normative Ab-An-Or for the plutonic rocks of the study area (O`Connor, 1965), (c) AFM diagram for determining sub-magma calc- and (d) ACF diagram determining I-type and S-type granitoid(Hyndman, 1986) Fig.5. Position of Onzon-Kanbani plutonic sampleson Y versus Nb and Rb versus Y+Nb diagram(Pearce et al., 1984). Abbreviations: ORG=oceanic ridge granite, VAG=volcanic granite, WPG=within plate granite and syn- COLG=syn-collision granite 7. Mineralization and associated hydrothermal alterations Gold and base metal mineralization hosted by marble is closely associated with intense hydrothermal alteration. Generally, mineralization is controlled by NE-SW trending faults within fracture and shear zones. Open space fracture filling veins are common characteristicswith minor disseminated mineralization in marble. Many kinds of vein textures are observed in mineralization vein such as massive vein, crustiform, banded, lattice, bladed carbonate, comb, and cockade. Some of the texturesare diagnostic textures of boiling (lattice, bladed, banded, crustiform). They are indicated to boiling fluids of near neutral to alkaline pH condition (Gregg and Jaireth, 1995; Simmons and Christenson, 1994) (Fig. 7). Many local worksites are working on the narrow mineralization zones where the width of veins are generally 0.5 to 5 meters. Wall rock alterations related with hydrothermal fluid are observed in Onzon-Kanbani area but not wide area scale. Mostly, hydrothermal alteration halos are developed around mineralization veins as narrow zones. Basically, hydrothermal alteration is overlapped to regional metamorphism. Microscopic observation and X-ray diffraction patterns are used to identify the type of alterations which happen by hydrothermal impact. There are three distinct hydrothermal alteration zones from proximal to distal of hydrothermal conduct. Silicic alteration zone or inner core of alteration halos, it is mainly composed of quartz, calcite, adularia and minor amount of illite and chlorite (Fig.6). Generally, this alteration is overlapped with mineralization vein but groundmass is strongly 196 Zar A.T. et al./ JGEET Vol 02 No 03/2017 silicified. Gold and base metal mineralization are observed in massive and banded quartz veins. Hydrothermal breccia is also frequently observed near this alteration zone. These breccia are characterized by a milled matrix of pyrite. Some of the sulphides are oxidized because of deep weathering. Sericite-illite alteration is observed as narrow zone next to silicic alteration zone. But this zone is not well developed in some alteration halos. The main constituents of minerals from this altered zone are sericite, illite, quartz, calcite and a minor amount of pyrite. Sericite occurs as fine grained and spread out like dusty (Fig. 6). Propylitic alteration is an outer most zone of alteration and wild area coverage. This zone is characterized by the presence of chlorite, epidote,actinolite, smectite, and illite, (Fig. 6). It is still preserve the primary texture of the original rock. It is believed that some part of propylitic alteration is not related to ore forming hydrothermal system (Evans, 1987), overlapped to regional metamorphism. Most of hydrothermal minerals from each altered zones showed that near neutral condition of pH (e.g. adularia, calcite, illite, sericite and chlorite). Fig. 6. Photomicrographs of (a & b) Silicic alteration, (c & d) Sericite-illite alteration zone, (e & f) Propylitic alteration zone. Abbreviations: calcite (Cal), quartz (Qtz), adularia (Adl), sericite (Ser), illite (Ilt), epidote (Epi), chlorite (Chl) and opaque mineral (Opq). 8. Geochemistry of altered rocks The major and trace elements concentration of the altered rocks are varied depend on alteration intensity as well as the presence of a chemical ion exchange between wall rocks and hydrothermal fluids. The altered zonation reflects changes in the fluid composition with time and interaction of hydrothermal fluid and wall rocks (Meyer and Hemley, 1967). Fig. 7. Some of themineralization vein textures (a) Lattice texture, (b) bladed calcite, (c) banded vein texture and (d) crustiform texture In Onzon-Kabani area,alteration zones are basicallyhosted in marble unit as narrow zonation. The major and trace elements of the least-altered rocks and altered rocks of each zones are shown in Table 1 and 3. In this case each of the alteration zones has measured enrichment and depletion of major and trace elements relative to the least- altered rock (Fig. 8).The petrochemistry of zone 1 showed that silicic altered rocks are enriched in SiO2, Al2O3, K2O, and S indicating occurrences of abundant quartz, aluminium-bearing clay (illite), ± adularia and sulphides whereas any other elements such as FeO, MgO, MnO and CaO are depleted. But in zone 2 of sericite-illite alteration zone, SiO2 is quite reduced compared with silicic alteration zone. Instead of SiO2, CaO is increased in remarkable amountbut still lowrelatively to least-altered rocks.Moreover, Al2O3, K2O, FeO and MgO are also high because of abundant illite (sericite) and chlorite. propylitic alteration zone , CaO shows high amount near least-altered rocks whereas Al2O3 and K2O are depleted. Locally enrichments of MgO, Al2O3 and FeO are indicated that the development of chloritization in propylitic alteration. The wt.% of loss of ignition (LOI) increase significantly to least altered samples (marbles). This is due to dissociation of CaCO3 and dolomite CaMg (CO3)2 that partially transform themselves into carbon dioxide gas at temperatures higher than 750° C. Generally, high field strength elements of Al, Ti, and Zr were assumed to be immobile elements during the alteration and deformation process. When plotting these minerals from least-altered and altered rocks in TiO2 vs Zr and TiO2 vs Al2O3 binary/bivariate diagrams, a general single trend of alteration is observed in both of diagrams but some of silicic and sericite-illite alteration samples are a little bit deficient from these lines (Fig.9 ).It mean hydrothermal alteration of silicic and sericite-illite alteration is quite high intensity. Zar A.T. et al./ JGEET Vol 02 No 03/2017 197 Fig.8 Enrichment depletion diagram showing major oxides (wt%) and trace element (ppm) during alteration in different zones of hydrothermal alteration of Onzon-Kanbani area based on mean data of least-altered samples as a reference for calculations, (a) and (b) for silicic alteration zone, (c) and (d) for sericite-illite alteration zone, and (e) and (f) for propylitic alteration zone Fig.9 Binary diagrams Zr-TiO2 and TiO2-Al2O3 showing plot of the least-altered and altered rocks with alteration trend 198 Zar A.T. et al./ JGEET Vol 02 No 03/2017 Table 2. Major and trace element composition of plutonic rocks from Onzon-Kanbani area Sample ID ZYKI-2 (luc) ZYKI-3 (luc) ZYK-5 (luc) ZYK-9 (syn) ZYK- 11 (syn) ZYK- 12 (Gr) ZYK- 18 (luc) KB(Gr) ZYKS-1 (luc) ZYKS-2 (syn) ZYKS-3 (luc) SiO2(%) 74.27 75.4 75.49 78.85 73.73 79.77 61.51 79.07 75.63 75.51 71.53 TiO2 0.03 0.27 0.03 0.07 0.38 0.26 0.2 0.01 0.05 0.34 0.33 Al2O3 13.65 12.48 13.09 11.85 12.69 5.09 13.02 5.34 12.38 12.08 13.91 FeO 0.23 2.43 0.21 1.21 3.1 1.73 1.8 0.55 1.77 1.18 2.56 MnO 0.01 0.03 0.02 0.01 0.07 0.05 0.03 0.01 0.01 0.03 0.06 MgO 0.02 0.32 0.05 0.16 0.16 0.29 0.81 0.28 0.47 0.53 0.47 CaO 0.28 0.89 0.57 3.13 1.17 7.52 6.88 9.57 1.08 1.26 1.42 Na2O 1.14 2.78 1.2 2.76 2.44 1.15 2.82 2.65 2.42 2.51 1.99 K2O 9.68 5.03 8.78 0.78 5.51 2.35 8.86 2.12 5.48 5.25 6.32 P2O5 0.02 0.02 0.02 0.01 0.04 0.06 0.01 0.01 0.03 0.06 0.01 LOI 0.5 0.22 0.31 0.63 0.48 0.51 3.3 0.32 0.61 1.2 1.12 Total 99.83 99.87 99.77 99.46 99.79 99.78 99.24 99.93 99.23 99.15 99.72 V(ppm) 6 6 5 2 18 14 15 7 21 2 8 Cr 22 24 24 27 20 30 22 20 19 24 23 Co 21 9 10 13 2 7 12 4 2 17 4 Ni 27 26 25 21 28 26 23 24 24 21 23 Cu 3 4 7 8 9 6 50 7 5 7 8 Zn 8 103 4 20 93 51 12 65 63 46 62 Pb 20 27 35 11 25 25 43 28 35 25 21 As 5 8 8 6 10 6 10 9 8 5 9 Mo 12 25 33 14 27 17 16 16 12 18 15 Rb 437 296 336 27 291 165 359 187 281 378 308 Sr 276 35 263 33 56 266 560 267 225 617 596 Ba 644 211 660 11 214 1033 4552 1015 484 1246 1568 Y 29 72 21 6 41 39 66 37 5 25 45 Zr n.d 473 429 37 731 249 17 14 122 425 476 Nb 2 14 1 1 9 15 32 22 14 12 3 Note: Total Fe content expressed as FeO(tot); n.d= below detection limit; major element and LOI are weight percent; trace elements are in ppm Table 3. Result of XRF and ICP-OES altered host rock from Onzon-Kanbani area, Thabeikkyin Township, Mandalay region, Myanmar Silicic Alteration Sericite alteration Propylitic least-altered GM-8 GM-9 GK-3 GK-5 CHL1 GS1 GM11 mean (n=4) SiO2 (%) 72.507 75.66 38.975 12.556 39.396 5.735 16.169 5.7737 TiO2 0.25 0.117 0.497 0.184 0.36 0.182 0.009 0.1217 Al2O3 12.582 13.649 10.708 3.127 5.428 1.888 0.51 1.5165 FeO 0.796 0.347 5.789 1.003 2.03 0.772 0.469 0.7797 MnO 0.027 0.001 0.202 0.129 0.049 0.035 0.105 0.032 MgO 0.697 0.212 3.242 0.994 11.675 1.996 8.134 3.0202 CaO 2.269 0.703 18.791 45.956 22.449 52.199 39.786 51.7112 Na2O 0.137 1.889 0.022 0.001 0.005 0.006 0.001 0.0867 K2O 6.521 5.587 3.033 0.609 0.542 0.58 0.003 0.5872 P2O5 0.032 0.02 0.09 0.022 0.099 0.011 0.002 0.009 S 0.4396 0.0127 1.8 0.0318 0.0377 0.0851 0.0108 0.0564 LOI 3.55 1.62 16.06 35.31 17.82 36.42 34.76 35.585 Zar A.T. et al./ JGEET Vol 02 No 03/2017 199 Total 99.8076 99.8177 99.209 99.9228 99.8907 99.9091 99.9588 99.2232 V(ppm) 11 6 163 17 32 22 n.d 12.25 Cr 18 19 554 34 46 45 24 40.25 Co 8 22 20 n.d 15 24 16 18.75 Ni 24 24 194 24 27 27 19 24.25 Cu 18 12 92 10 9 11 4 8.5 Zn 88 71 535 68 67 33 18 28.5 Pb 89 60 210 14 4 1 n.d 27.25 As 39.33 2.92 3267.87 n.d n.d 172.26 n.d 4.5 Ba 866 1051 224 49 104 84 5 67.5 Nb 14 9 4 6 8 1 n.d 1 Rb 289 201 120 43 30 29 2 25.25 Sr 124 248 317 367 199 473 199 403 Y 9.32 5.81 17.67 6.43 8.42 n.d 2.78 8.25 Zr 267 75 111 32 537 17 n.d 18.25 Fig.10 Ore microscopic images of selected samples (Py=pyrite, Gn=galena, Sp=sphalerite, Ccp=chalcopyrite, Au=native gold and Elt=electrum) 9. Ore mineralogy and paragenetic sequence Mineralogically, gold occurs as free grains or locked within pyrite, sphalerite, galena and gangue of Au. Electrum (<80 at %) is mostly observed as large grained in gold bearing quartz vein but native gold (>80 at %)is observed as fine grained in base metal quartz-carbonate vein and carbonate base metal sulphides vein (Fig.11). Other common ore minerals in research area are pyrite, marcasite, chalcopyrite, sphalerite, galena, arsenopyrite, chalcocite, covellite, hematite, and goethite. Pyrite, galena, sphalerite, chalcopyrite, marcasite, and arsenopyrite are primary ore minerals whereas chalcocite, covellite, hematite, and goethite occur as late minerals, their occurrences reflect the oxidation of primary sulphides such as pyrite and chalcopyrite by circulation of surficial water. Pyrite is the most abundant sulphide mineral in the ore body. It occurs over the entire period of mineralization as fine-grained massive aggregates to large euhedral grains. According to thevein and mineral structures and textures, there are three main paragenetic stages; 1) mineralization stage, 2) barren stage and 3) oxidation stage (Table-4). In mineralization stage, the early formed quartz, pyrite, and minor calcite minerals are observed away from late phase 200 Zar A.T. et al./ JGEET Vol 02 No 03/2017 sulphides and quartz core vein. And also early formed pyrite and quartz minerals showed their euhedral crystal forms whereas anhedral sphalerite is younger than quartz and pyrite in order of deposition. Some of theanhedral sphalerites are replaced along the boundary by later formed galena. Moreover, disseminated chalcopyrite rods and small grainsoccur in sphalerite as exsolution texture (Fig. 10). Gold is mostly observed in quartz gangue, pyrite, sphalerite, galena and chalcopyrite ground mass as disseminated specks (Fig. 10). Actually, quartz, calcite, and pyrite are observed the entire period of mineralization as more or less amount. Sericite and aminor amount of adularia are also found together with quartz at mineralization vein. After mineralization stage, veins are barren like a calcite or quartz vein with very minor amount of pyrite. Subsequently, oxidation stage is going on by circulated meteoric water whereas hematite, goethite,and chalcocite are formed from primary sulphides. Table 4. Generlized paragenetic sequence of Onzon- Kanbani area Fig.11 Back scatter image of electrum gold and native gold in mineralization vein (Elt=electrum, Au=native gold, Sp=sphalerite, Py=pyrite, Qtz=quartz) 10. Fluid inclusion study Double polished quartz wafers were prepared for fluid inclusion study. From petrographic study, two-phase (liquid, vapor) fluid inclusions are dominant type of primary fluid inclusion. They are observed as two-phase liquid rich, two-phase coexisting of liquid-rich and vapor-rich and two phase vapor-rich fluid inclusions. Moreover, microthermometry was carried out for primary fluid inclusions in quartz from gold and base metal mineralization veins. Homogenization temperature Th of fluid inclusion showed range from 159°C to 315°C where the boiling temperature was estimated to be 170°C. The histogram of homogenization temperature is shown in figure (Fig. 12). Salinities of the fluid inclusions were temperature Tm (Bodnar, 1993). The salinity range is low to moderate 0.88 to 12.51 wt% NaCl equivalent. The plot diagram of homogenization temperature and salinity are showed negative trend (Fig. 13). Fig.12 Homogenization temperatures of fluid inclusion in quartz from gold and base metal mineralization vein Fig. 13. Binary plot diagram ofsalinity vs. homogenization temperature Th of fluid inclusions 11. Discussion and conclusion Gold mineralization in Onzon-Kanbani area ishosted in metamorphic rocks. The older metamorphic rocks are intruded by younger plutonic rocks. Mineralization is commonly observed as fracture filling vein and disseminated nature hosted in marble unit. Petrochemistry of host rocks is mainly controlled by regional metamorphism and hydrothermal activities. Basically, host rocks are rich in CaO and MgO whereas the notable amount of Al2O3 content is showed their mica content in marble. - - of granitoid rocks are observed as intrusive bodies where most of the rocks are placed in the field of Zar A.T. et al./ JGEET Vol 02 No 03/2017 201 syn-collisional granite and within plate granite. Hydrothermal alteration halos are developed as narrow zones beside of hydrothermal conduit or mineralization vein. They are silicic, sericite-illite and propylitic alteration zones from proximal to distal of hydrothermal conduits. Hydrothermal alteration in Onzon-Kanbani area is regard as low- sulphidation epithermal system as indicated by the characteristic of alteration style and alteration mineral assemblages such as quartz, calcite, ±adularia, sericite, illite and smectite. These alteration minerals are showed that the temperature decreasing to the outer zone of alteration as well as indicated that the higher pH, near neutral condition of hydrothermal system. Generally, hydrothermal alteration is overlapped to regional metamorphism. The geochemistry of each altered zone reflects changing of fluid composition and interaction of hydrothermal fluid and wall rock. According to immobile elements characteristics of least-altered and altered rocks, alteration intensity is higher to silicic and sericite-illite alteration. SiO2 and CaO content are inversely proportional in each altered zone. Enrichments of S, Pb, Zn, and Cu from silicic altered zone indicate that fracture filling vein mineralization is more common than disseminated mineralization. In ore mineralogy, hypogene ore mineral such as pyrite, sphalerite, galena, chalcopyrite and minor native gold and electrum are precipitated in mineralization stage. After this veins are barren by deposition of calcite or quartz at the end of mineralization stage. Some of hypogenesulphide minerals are oxidized to supergene minerals during oxidation stage. According to fluid inclusions petrography whereas coexisting of liquid rich and vapor rich fluid inclusions as well as some of vein textures such as bladed, banded and lattice are strongly advocated that fluid boiling, iseffective on such a precipitation of ore minerals. Moreover, homogenization temperature (159°C-315°C) and salinity (0.88 to 12.51 wt.% NaCl equiv.) range are acceptable to say it formed in the epithermal environment. Acknowledgements This research is supported by AUN/SEED-Net (JICA program).We would like to thank all of local companies and owners for permission to conduct research work in there and for helping during field investigation and general discussion. References Barley, M.E., Pickard, A.L., Zaw, K., Rak, P., Doyle, M.G., 2003. Jurassic to Miocene magmatism and metamorphism in the Mogok metamorphic belt and the India-Eurasia collision in Myanmar. Tectonics 22, n/a-n/a. doi:10.1029/2002TC001398 Bender, F., 1983. Geology of Burma, 293 p. Gebrüder Borntraeger, Berlin and Stuttgart. Bodnar, R.J., 1993. Revised equation and table for determining the freezing point depression of H 57, 683 684. Evans, A.M., 1987. An Introduction to Ore Geology, 2nd edn. ed. Blackwell, Oxford. Gregg and Jaireth, S.D.G. and M., 1995. Quartz textures in epithermal veins, Queensland; classification, origin and implication. Econ. Geol. 90, 1841 1856. Hyndman, D.W., 1986. Petrology of Igneous and Metamorphic Rocks. Geol. Mag. 123, 88 89. doi:10.1017/S001675680002673X Metcalfe, I., 2009. Late Palaeozoic and Mesozoic tectonic and palaeogeographical evolution of SE Asia. Geol. Soc. London, Spec. Publ. 315, 7 23. doi:10.1144/SP315.2 Meyer, C., Hemley, J.J., 1967. Geochemistry of hydrothermal ore deposits. Holt, Rinehart and Winston, New York. Middlemost, E.A.K., 1994. Naming materials in the magma/igneous rock system. Earth-Science Rev. 37, 215 224. doi:10.1016/0012- 8252(94)90029-9 Mitchell, A.H.G., 1979. Guides to metal provinces in the Central Himalaya collision belt; the value of regional stratigraphic correlations and tectonic analogies. Mem. Geol. Soc. China 3, 167--194. Mitchell, A.H.G., Ausa, C.A., Deiparine, L., Hlaing, T., Htay, N., Khine, A., 2004. The Modi Taung - Nankwe gold district, Slate belt, central Myanmar: Mesothermal veins in a Mesozoic orogen. J. Asian Earth Sci. 23, 321 341. doi:10.1016/S1367-9120(03)00138-X Mitchell, A.H.G., Chung, S.-L., Oo, T., Lin, T.-H., Hung, C.-H., 2012. Zircon U Pb ages in Myanmar: Magmatic metamorphic events and the closure of a neo-Tethys ocean? J. Asian Earth Sci. 56, 1 23. doi:10.1016/j.jseaes.2012.04.019 Myint, T.A., Than, T.N., Min, A., 2014. Precious and Base Metal Mineralization in Kwinthonze- Nweyon area, Singu and Thabeikkyin Townships, Mandalay Region, Myanmar. Proc. Sundal. Resour. 2014 MGEI Annu. Conv. 343 354. O`Connor, J.T., 1965. A classification of quartz rich igneous rock based on feldspar ratios. US Geol. Surv. 525B, B79 B84. Pearce, J.A., Harris, N.B.W., Tindle, A.G., others, 1984. Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. J. Petrol. 25, 956 983. Searle, D.., Haq, B.T., 1964. The Mogok Belt of Burma and Its Relationship to the Himalayan Orogeny. Proc. Int. Geol. Congr. 22, 132 161. Simmons, S.F., Christenson, B.W., 1994. Origins of calcite in a boiling geothermal system. Am. J. Sci. doi:10.2475/ajs.294.3.361 Swe, W., 1972. A Strike-slip faulting in central belt of Burma [abstr.]. Reg. Conf. Geol. SE Asia, Kuala Lumpur. Annex. Geol. Soc. Malaysia Newsl. 34, 59. Thein, M., Win, S., 1969. The metamorphic petrology, structures and mineral resources of the Shantaung-U-Thandawmywet Range, 202 Zar A.T. et al./ JGEET Vol 02 No 03/2017 Kyaukse district. Burma Res. Congr. 3, 487 514. Thein, M.L., Myint, O., Kyi, S., Win, H.N., 1990. Geology and stratigraphy of the metamorphosed early Paleozoic rocks of the Mogok- Thabeikkyin- Singu- Madaya Areas. Yangon. 1. Introduction 2. Methods of study 3. Regional geologic setting 4. Geology of Onzon-Kanbani area 5. Petrography 6. Petrochemistry 6.1 Petrochemistry of host rocks 6.2 Petrochemistry of intrusive igneous rocks 7. Mineralization and associated hydrothermal alterations 8. Geochemistry of altered rocks Table 4. Generlized paragenetic sequence of Onzon-Kanbani area 10. Fluid inclusion study 11. Discussion and conclusion Acknowledgements References