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PT J
AU Wang, CM
Chen, JY
Yang, LF
Zhang, D
Du, B
Shi, KX
AF Wang ChangMing
Chen JingYuan
Yang LiFei
Zhang Duan
Du Bin
Shi KangXing
TI Tectonic-fluid-mineral system in the Lanping basin, Sanjiang Tethys
SO ACTA PETROLOGICA SINICA
AB The Lanping area in the middle part of western Sanjiang Tethys experienced a complex collisional process, resulting in prolonged and extensive metal depositions from diverse types of mineralization and the consequent superimposed metallogenesis. Despite extensive research carried out on spatio-temporal framework of collisional orogeny and the related mineralization, the superimposed mineralization, fault-controlling types, and metal enrichment is still not well addressed. This paper, we will aim at the collisional orogeny and superimposed mineralization such as the Jinding and Jinman deposits, focusing on the basin brines and hydrothermal fluids, analyzing tectonic-fluid-mineral system by LA-ICP-MS zircon U-Pb and fluid inclusion. Zircon U-Pb dating of the gneissic granite and monzogranite from the western margin of Lanping basin yield the upper intercept and weighted mean ages of 1067 +/- 20Ma and 206 +/- 1Ma, representing the metamorphic age from the Precambrian basement and post-collisional age of Changning-Menglian Tethys Ocean, respectively. The tectonic history of the Lanping basin is a complex process, involving the earliest formation of basement, the Middle Permian-Middle Triassic foreland-basin, the Late Triassic post-collision extension and rift basin, Jurassic Cretaceous depression-basin, Paleocene-Early Oligocene foreland-basin, and Late Oligocene-Miocene strike-slip and pull-apart basin. There exist three types of Pb-Zn-Cu-Ag-Au-Sb-Hg mineral systems related to the Lanping orogenic basin: (1) Mesothermal vein type Cu-Ag mineral system, as examples of Jinman and Liancheng deposits. Paleocene-Early Eocene (56 similar to 46Ma) Cu mineralization were superimposed by Oligocene-Miocene ( 32 similar to 21Ma) Pb-Zn mineralization. Fluid inclusions have characterized by homogenization temperatures predominately of 210 270 degrees C and salinities of 0. 9% similar to 20. 5% NaCleqv, indicative of basinal brines as the source of ore forming fluids with contribution from a minor metamorphic fluids; (2) Epithermal Sb-Au-Hg-As mineral system, as an example of the Bijiashan deposit. Ore-forming ages focuses on Middle-Late Eocene. Fluid inclusions have characterized by homogenization temperatures predominately of 145 200 degrees C and salinities of <6. 0% NaCleqv, indicative of meteoric water as the source of ore-forming fluids; (3) The Mississippi Valley-Type Pb-Zn mineral system, as an example of Jinding deposit. Ore-forming ages range mainly from 32Ma to 21Ma. Fluid inclusions have characterized by homogenization temperatures predominately of 80 190 degrees C and salinities of 1. 6% similar to 18% NaCleqv, indicative of basinal brines meteoric water as the source of ore-forming fluids. Finally, this paper discusses the tectonic-fluid-metallogenic processes of the Lanping basin. This research is not only useful for interpretation of the basin brines and magmatic-hydrothermal mineral system of the Lanping basin, but also significant for research on the collisional orogeny and superimposed mineralization.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 1957
EP 1977
UT WOS:000408702200001
ER  

PT J
AU Liu, Y
Chen, C
Shu, XC
Guo, DX
Li, ZJ
Zhao, HX
Jia, YH
AF Liu Yan
Chen Chao
Shu XiaoChao
Guo DongXu
Li ZiJing
Zhao HaiXuan
Jia YuHeng
TI The formation model of the carbonatite-syenite complex REE deposits in the east of Tibetan Plateau: A case study of Dalucao REE deposit
SO ACTA PETROLOGICA SINICA
AB Mianning-Dechang (MD) REE Belt is located in the east of Tibetan Plateau and western Sichuan Province, southwestern China. It is controlled by a series of cenozoic strike-slip faults. Dalucao REE deposit is the only large deposit identified in the southern part of the MD REE Belt. Detailed comparison including metallogenic characteristics, host rock alteration, ore types, source of ore forming fluids and evolution of fluid inclusions of Dalucao and other deposits within MD REE Belt has been concluded based on latest geological surveys, studies on petrographic features; and the metallogenic process of carbonatite-type (including carbonatite-syenite complex) REE deposits is summarized The No. 1 and No. 3 orebodies in Dalucao deposit are both hosted in breccia pipes, located in carbonatite-syenite host rocks. Previous studies suggested that both No. 1 and No. 3 orebody in Dalucao deposit are formed at about 12Ma, but the latest research indicate there had already exist magmatic activity of carbonatite-syenite complexes at about 26. 49 +/- 0. 63 Ma. And the ores in Dalucao deposit are mainly classified as weathered and breccia type ores; the high levels of brecciation and weathering in the Dalucao deposit make it difficult to recognize the ore veins or gangue minerals from the hand specimen or field of microscope. Based on field observations, study of paragenetic association of minerals and analyses of inclusion in these REE deposits, the total mineralization in Dalucao deposit is similar to that of Maoniuping except for the smaller size of Dalucao REE deposit. The mineralization process can be divided into magmatic stage, pegmatite stage ( > 600 degrees C), high-temperature hydrothermal stage (450 similar to 350 degrees C) and low-temperature hydrothermal stage ( < 350 degrees C), the bastnasite precipitated during the later period of low-temperature hydrothermal stage. Based on the geological characteristics of inclusions found in pegmatite and hydrothermal fluids, the multiple episodes of explosive breccia activities leads to the addition of meteoric water and CO, deriving from the decarbonation of carbonatite; the density (0. 732 similar to 0. 631g/cm(3)) and pressure (2436 similar to 101bar) of the ore forming fluids gradually decreased. Meanwhile, various types of inclusions are found within the mineralization stages by the microscopic observation and Raman analysis. The variation of inclusion types changed from melt-inclusions to CO2-riched and gas-liquid inclusions bearing daughter minerals such as barite, fluorite and celestite, indicating the conversion process of ore-forming fluid changing from magmatic to hydrothermal fluid. The anion of inclusions in Dalucao REE deposit is mainly composed of SO42- ; CO2 count for most of gas in inclusions; the cations in the ore-forming fluids may mainly contain K+ , Na+ , Ca2+ , Sr2+ , Ba2+ and rare earth cations, all of these mentioned above reflected that the ore forming fluids are belong to SO42--Co-2-H2O system, and this is consistent with those of other REE deposits in the MD Belt. The mainly components of the ore forming liquids is magmatic water, meteoric water and CO2 originated from the decarbonation of carbonaite. And the latter may changed the 0 isotopic compositions of the hydrothermal calcite and bastnasite relative to the bulk primary carbonatite (bastnasite and calcite; delta O-18 = 5. 8 parts per thousand similar to 12.
5 parts per thousand) along the whole REE belt. Existing studies indicate that that the carbonatite-syenite complexes and mainly gangue mineals such as fluorite, hydrothermal calcite, barite, and celestite in these REE deposits have slightly contrasting Sr-Nd-Pb isotopic compositions, indicating materials of gangue minerals may come from carbonatite-syenite complexes. Faulting and cryptoexplosive brecciation events promoted the circle of ore-forming fluid, and resulted in the formation of cryptoexplosion breccia type and weathered ore in Dalucao REE deposit. Although an epigenetic oxidation stage can be recognized in the Maoniuping and Dalucao deposits, it was not accompanied by REE mineralization, the hydrothermal stage was the main stage of REE deposition. And due to the high proportion of carbonatite in carbonatite-syenite complexes, fenitization which has nothing to do with the REE mineralization can be found both in Lizhuang REE deposit and the No. 3 orebody in Dalucao REE deposit, rather than the Maoniuping REE deposit. Based on the studies above, we try to establish the ore formation model of carbonatite-syenite type REE deposit of Mianning-Dechang REE belt in western Sichuan Province.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 1978
EP 2000
UT WOS:000408702200002
ER  

PT J
AU Deng, MG
Zhao, JX
Liu, FX
Yu, HJ
Sun, BD
Liu, F
Li, SB
AF Deng MingGuo
Zhao JianXing
Liu FengXiang
Yu HaiJun
Sun BaiDong
Liu Fei
Li ShiBin
TI Discussion on sources of metallogenic fluids and materials of the Shuitoushan Pb-Zn deposit in Zhenkang, western Yunnan: Evidence from H, O, S and Pb isotopes
SO ACTA PETROLOGICA SINICA
AB Shuitoushan Pb-Zn deposit is a low temperature type deposit, which was one of the significant results from the Zhenkang Pb-Zn-Fe-Cu polymetallic ore concentration area in Baoshan block, western Yunnan. The ore bodies of this deposit occurred as either stratiform-like or lentiform within the marbleization-limestone of the Upper Cambrian Baoshan Formation, and was controlled by NEE trending fault, with sphalerite and galena as main and chalcopyrite and pyrite as occasionally ore minerals; dolomite, chlorite, calcite, quartz and sericite as dominant gangue minerals. Based on the detailed study of the geological features of the deposit, combined with H, O, S and Pb isotope compositions, this paper focused on the sources of metallogenic fluids and materials, and compared with the adjacent Luziyuan super-large Pb-Zn-Fe-Cu polymetallic deposit. This research indicates that the values of delta D and delta(18) O-H20 of quartz in the deposit range from - 101. 1 parts per thousand to - 93. 3%parts per thousand with average of - 96. 85 parts per thousand (n = 4) and from 3. 37 parts per thousand to 3. 77 parts per thousand with average of 3. 57 parts per thousand (n = 4) respectively, implying magmatic as dominant early metallogenic fluids, while increasing gradually mixed with meteoric water later. delta S-34 values of the sulfides are all positive, varying from 4. 1 parts per thousand to 12. 2 parts per thousand with average of 8. 23 parts per thousand ( n = 10), and approaching delta S-34 values (8. 9 parts per thousand to 12 parts per thousand) of the adjacent Luziyuan deposit. This deposit can be divided into three metallogenic phases, phase II is the main metallogenic stage of the deposit related to sphalerite and galena (5 values are mainly concentrated between 4. 1 parts per thousand to 6. 2 parts per thousand). The delta S-34(Avemge) can be used to represent approximately the delta(34)(Sigma S), of metallogenic hydrotherm i.e. delta(34) (Sigma S) approximate to delta S-34(Average) = 6. 56 parts per thousand (n=7) .delta(34) S values of sphalerite and galena are partially overlapped, but have the distribution characteristics of delta(34)(Ssphalente) > delta S-34(Galena), and delta S-34(Dark-brown) > delta S-34(Brown) > delta S-34(light -brown) between the different colors of sphalerite on the whole, showing a sulfur isotope equilibrium fractionation, that S isotopic compositions are relatively stable, that the Shuitoushan deposit has the characteristics of the deep crustal magma in origin. Pb isotope analysis of metal sulfides in this deposit is made, and the results show that it is very concentrated ( ranges from 18. 3408 to 18. 4483 with average of 18. 3815, and from 15. 8337 to 15. 9440 with average of 15. 8745, and from 38. 8224 to 39. 4391 with average of 38. 9941 respectively for Pb-206/Pb-204, Pb-207/Pb-204 and Pb-208/Pb-204, n = 10). The points are mainly distributed above the upper crust evolution line, indicative of primarily the upper crust materials related to magmatism.
This paper argues that the deep crustal magmatic hydrotherm in the mining area is the most important sources of metallogenic fluids and materials in the Shuitoushan deposit, that the mixing of fluids is an important mechanism for the precipitation and enrichment of metal elements, that the deposit is characterized by low temperature and epigenetic mineralization, speculating that the formation of the deposit is related to magmatic hydrothermalism of Late Yanshan epoch.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2001
EP 2017
UT WOS:000408702200003
ER  

PT J
AU Zhang, XF
Li, WC
Yin, GH
Yang, Z
Tang, Z
AF Zhang XiangFei
Li WenChang
Yin GuangHou
Yang Zhen
Tang Zhong
TI Geological and mineralized characteristics of the composite complex in Xiuwacu W-Mo mining district, NW Yunnan, China: Constraints by geochronology, oxygen fugacity and geochemistry
SO ACTA PETROLOGICA SINICA
AB The Xiuwacu W-Mo deposit is located at the north of Shangri-La area, southern part of Yidun arc and its reserve has reached to medium-large size ore deposit. This is a composite complex that is composed of two-period intrusions (biotite granite of Late Triassic and porphyry monzogranite of Late Cretaceous) in Xiuwacu district, while the W-Mo deposit was formed during 82 similar to 86Ma. However, there are no explicit reports about the relationship between these two intrusions of different ages and whether the Late Triassic intrusion had contributed to the W-Mo metallogenesis. So, the authors try to answer these questions by geochronology, oxygen fugacity and other ways, after the research of their forming dating and geochemistry characteristics of these two intrusions, wishing to reveal their metallogenic characteristics and offer some theoretical support for the prospecting practice. Research shows that the crystalline age of biotite granite is 211. 7 +/- 2. 6Ma with high SiO2 (69. 48% similar to 73. 73%), belonging to shoshonitic series, metalumnious, enrichment of LREE and LILE, depleted in HREE and HFSE of Nb , Sr , Ti, with weak negative Eu abnormal, high magmatic oxygen fugacity (f(o2) = - 19. 4 similar to - 9. 1, average -13.7); While the crystalline age of porphyry monzogranite is 76. 8 +/- 3. 8Ma with the age in a core of the zircon grains as 219 2. 6Ma, and the rock has the similar geochemical characteristics with the former, high SiO2 (67. 35% similar to 75. 65%), belonging to shoshonitic series, metalumnious, but the rock has higher REE (higher than the biotite granite), significant negative Eu anomaly (greater than the biotite granite), relatively lower magmatic oxygen fugacity (f(o2) = - 30. 4 similar to - 18. 2, average - 23. 4). Based on the above, combining with the widely distributed of faults in Xiuwacu district, two periods intrusions are contacted with each other along F-4 with nearly SN strike, and the NW strike wrench faults (F-1 -F-3,) are ore control structures. This paper argues that there was an inheritance relation between the later porphyry monzogranite and the former biotite granite. The biotite granite was rooted in fraction melting of the lower crust just over the Ganzi-Litang Ocean westward subduction zone in Late Triassic, thus the magma was enriched with water and had high oxygen fugacity, which was effectually to form Cu-Au deposits, and this has been partially proved in practice. While the porphyry monzogranite was rooted in fraction melting of the thickened lower continental crust, as the magma had less water and lower oxygen fugacity, it has the potential to form W-Mo deposits. In a word, as the magmatic hydrothermal fluid was migrating along the fault-crack system in this area in Late Cretaceous, it inherited and developed the former intrusion and finally formed the aplite veinlets and the Xiuwacu W-Mo deposit in this area.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2018
EP 2036
UT WOS:000408702200004
ER  

PT J
AU Wang, DB
Tang, Y
Luo, L
Liao, SY
Yin, FG
Wang, BD
AF Wang DongBing
Tang Yuan
Luo Liang
Liao ShiYong
Yin FuGuang
Wang BaoDi
TI Late Oligocene crustal anatexis and melt/fluid migration in the Ailao Shan tectonic belt: Evidences from zircon U-Pb ages and trace element compositions
SO ACTA PETROLOGICA SINICA
AB The Ailao Shan tectonic belt is an important tectonic boundary in southeast of the Qinghai-Tibetan Plateau and consists mainly of high-grade metamorphic rocks previously thought to be Paleoproterozoic basement rocks. In-situ LA-ICP-MS U-Pb age and trace element of zircons were determined for the Ailao Shan high-grade metamorphic rocks. Zircon U-Pb geochronological data indicate that the high-grade metamorphic rocks have various parent rocks with different intrusive/depositional ages of 728 +/- 8Ma, 727 +/- 3Ma and 231 +/- 4Ma and similar metamorphic ages of 27. 8 similar to 23. 7Ma. Our new results demonstrate that the high-grade metamorphic rocks from the Ailao Shan belt zone are a mixture of metamorphic both igneous and sedimentary rocks of different times, instead of solely Paleoproterozoic basement rocks. Migmatization and metamorphic crystallization of these rocks took place at 27. 8 similar to 23. 7Ma, indicating a significant period of crustal anatexis in the Ailao Shan tectonic belt. The syntectonic felsic dykes hosted by gneiss were derived from a mixture of locally-derived and allochthonous melts. The migmatized rocks from the Ailao Shan deformation zone were most probably the results of decompression melting following peak metamorphism. The crustal anatexis and left-lateral shearing were two synchronous metamorphic patterns resulted from a shared geological event. They interact and influence each other during exhumation of the Ailao Shan metamorphic zone in Late Oligocene.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2037
EP 2053
UT WOS:000408702200005
ER  

PT J
AU Tang, Y
Wang, DB
Liao, SY
Yin, FG
AF Tang Yuan
Wang DongBing
Liao ShiYong
Yin FuGuang
TI New understanding on Ximeng Group in Three River area, western Yunnan: Evidence from structural characterization and zircon U-Pb dating
SO ACTA PETROLOGICA SINICA
AB Located in the eastern margin of Baoshan-Shan Thai block, the Ximeng Group was long regarded as the only Precambrian metamorphic basement rocks exposed in China of this block. Without scientific and reliable data of geochronology and paleontology, the age of the metamorphic rocks is still controversial. Based on detailed macro- and micro-structural observations, the metamorphic rocks of Ximeng Group which shows domelike uplift can be divided into granitic mylonites and low grade metamorphic rocks. The former are distributed in core of the uplift and have experienced intensively ductile deformation. The latter are distributed in the rim and have the similar features of Pake Formation and Wangya-Yungou Formation. According to EBSD fabric analysis of quartz in the deformed rocks of Ximeng Group, it can reveal that the rocks closed to the core have experienced an early stage of deformation at intermediate temperatures (550 similar to 650 degrees C, corresponding to amphibolite facies) and a late deformation at low temperature (400 similar to 550 degrees C, greenschist facies), while the rocks near the rim of uplift have been deformed at low temperature (400 550 degrees C). In this paper, three samples of granitic mylonites were chosen for LA-ICP-MS zircon U-Pb dating, giving ages of 455 +/- 3Ma, 456 +/- 3Ma and 454 +/- 3Ma respectively. Combined with previous research results of geochronology and paleontology, it indicates that the protolith of the Ximeng metamorphic rocks may be composed of two parts. The first part is the Ordovician granite ( similar to 460Ma) and the other mainly comprises Cambrian carbonate, elastic rocks and minor basic volcanic rock. The former is highly deformed into mylonites during the ductile shearing, and the latter is transformed into phylite, schist and marble due to low grade metamorphism at low temperature (400 550 degrees C, greenschist facies). It also can be concluded that Ximeng Group should not be regarded as the Precambrian metamorphic basement rocks of Baoshan block.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2054
EP 2072
UT WOS:000408702200006
ER  

PT J
AU Li, XB
Wang, BD
Liu, H
Wang, LQ
Chen, L
Yan, GC
Zhou, F
AF Li XiaoBo
Wang BaoDi
Liu Han
Wang LiQuan
Chen Li
Yan GuoChuan
Zhou Fang
TI Petrogenesis of Early Jurassic volcanic rocks in the Amdo area, Tibet: Evidences for the subduction of the Bangong-Nujiang Tethys ocean
SO ACTA PETROLOGICA SINICA
AB It can better understand the geological evolution of the Tethys through studying Mesozoic volcanic rocks widely exposed in the Lhasa Terrane. This paper report LA-ICP-MS zircon U-Pb geochronology and zircon in situ Lu-Hf isotope, whole-rock analysis of major and trace elements and Sr-Nd isotope for the volcanic rocks in the Amdo area. LA-ICP-MS zircon U-Pb analysis suggest that the volcanic rocks formed at 180. 7 +/- 4. 7Ma, and reveal that they formed in the Early Jurassic. The SiO2, MgO and Fe2O3T of these volcanic rocks range from 62. 50% to 76. 15%, 0. 33% to 3. 05%, 2. 35% to 6. 69% , respectively. They are enriched LREE in the chondrite-normalized REE patterns with weak negative Eu anomalies, and are enriched in large ion lithophile elements (LILEs) and depleted in high field strength elements ( HFSEs). Zircon epsilon(Hf),(t) and whole-rock epsilon(Nd)(t) of these volcanic rocks have positive values and are from +15. 1 to +17. 1, from +7. 1 to +13. 2, respectively. These features suggest that Amdo volcanic rocks were probably produced by partial melting of new lower crust by the subduction of Tethys oceanic crust. Combining with regional geologic data, they were not originated from the subduction of Longmu Tso-Shuanghu Paleo-Tethys ocean or Yarlung Zangbo Neo-Tethys ocean, but Bangong-Nujiang Tethys ocean. Combining with the Jurassic magmatic arc in the Gerze and Rutog, they form the magmatic arc belt in the north side of Bangong-Nujiang Tethys ocean. Therefore, we suggest that the Early Jurassic island arc volcanic rocks in the Amdo area are the products of northward subduction of the Bangong-Nujiang Tethys ocean. These results provide direct evidence of the volcanic rocks for the subduction of the Bangong-Nujiang Tethys ocean.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2073
EP 2084
UT WOS:000408702200007
ER  

PT J
AU Cui, XL
Deng, J
Zhang, D
Xiao, CX
Zhang, QW
Wu, ZY
Zhou, SM
AF Cui XiaoLin
Deng Jun
Zhang Duo
Xiao ChangXian
Zhang QiWei
Wu ZhanYi
Zhou ShuMin
TI Chronological and geochemical characteristics of the Early Silurian metamorphic granites in Tengchong Block, western Yunnan and their implications
SO ACTA PETROLOGICA SINICA
AB The Early Paleozoic magmatic rocks, which are ubiquitous in the southwestern Tethys tectonic belt, are the product of the proto-Tethys accretionary orogenesis in the Gondwana continent. The current geochronological studies reported these plutons formed in the range of 536 similar to 448Ma. In this paper, a granitic outcrop formed in similar to 437Ma is first discovered in Gaoligongshan Group through LAICP-MS zircon U-Pb dating. The zircon Hf-isotope and bulk-rock major and trace element data of the granites are reported to further constrain the proto-Tethyan tectonic evolution. The major element data reveal these Early Silurian granites are high silicic (SiO2 = 72.78% similar to 73. 69%), high alkali (K2O + Na2O =7. 23% similar to 8. 70%) and peraluminous (A/CNK =1.08 similar to 1. 12). The trace element data exhibit they are relatively enriched in LREEs, LILEs ( Rb, K) and Pb, and depleted in HFSEs (Nb, Ta, P, Zr, and Ti), Ba, Sr and Eu. All the mineral assemblage characteristics and geochemical features of the rock simples are comparable to those of S-type granites attributed to partial melting of metasediments dominated by psammite with residual plagioclase in the source area. Zircon epsilon(Hf)(t) (- 9. 8 similar to - 6. 2) and t, ( 2. 0 similar to 1. 8Ga) also prove those S-type granites are mainly derived from the ancient crustal metasedimentary, with little mantle-derived components introduced into the melt. According to zircon saturation temperatures (T-zr) and Ti-in-zircon thermometer, the temperature decreases from similar to 794 degrees C to similar to 754 degrees C during the process of partial melting to magma consolidation. The high temperature of the melt indicates the mantle may as a source for the extra heat required for crustal anataxis. Previous research indicates in the Early Paleozoic Gondwana continental margin experienced proto-Tethyan subduction ( ca. 530 similar to 510Ma), accretionary orogenesis of microcontinental fragments and slab breakoff ( ca. 510 similar to 490Ma), lithospheric thickening ( ca. 490 similar to 475Ma), and lithospheric delamination ( ca. 475 similar to 460Ma). The demolition of the lithospheric mantle will lead to asthenosphere upwelling and continued extension of continental lithosphere. Under the tectonic extension, the granitic rocks emplaced in similar to 437Ma in Tengchong Block may be produced through partial melting of the ancient crustal metasediments dominated by psammite, and mantle may supply some extra heat for the partial melting process.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2085
EP 2098
UT WOS:000408702200008
ER  

PT J
AU Huang, YH
Deng, J
Li, GJ
Meng, FQ
Mao, FX
Zhang, PF
AF Huang YuHan
Deng Jun
Li GongJian
Meng FuQing
Mao FuXiang
Zhang PengFei
TI Metallization process and metallogenic sources of concealed porphyry-skarn Mo deposit, Laochang, western Yunnan
SO ACTA PETROLOGICA SINICA
AB Laochang concealed Cenozoic porphyry-skarn deposit has recently been reported as a unique Mo-dominant deposit in southern Sanjiang Tethyan orogenic belt, SW China. Previous studies were mainly focused on the petrogenesis of the porphyry, but the studies on the porphyry-skarn deposit have been rarely reported. In this paper, the petrology, EPMA and S-isotope experiments on Laochang porphyry-skarn Mo deposit were conducted to analyze the metallization process and materials sources. The metallization sequence of porphyry can be divided into diagenesis, potassic alteration and silicification stages. Sequence of skarn can identified as prograde, early-retrograde and late-retrograde stages. Porphyry and skarn are both altered in hydrothermal stage. Mineralogy and EPMA analysis show amphibole thermometer have crystallization temperature at 730 similar to 790 degrees C with oxygen fugacity (f(o2)) at NNO + 1. 6 similar to 2. 5, which proves diagenesis stage was hyperthermal and relatively reduced. Biotite thermometer in potassic alteration and silicification stage show porphyry cooling from 650 degrees C to 450 degrees C, oxygen fugacity rising from QMF + 1. 9 to QMF + 2. 5. Gathering of molybdenite in porphyry and precipitation of sulfide in skarn have strong connection to decreasing temperature and increasing oxygen fugacity. Ore body delta S-34(VCDT) (+ 3. 00 parts per thousand + 11. 00 parts per thousand) are consistent with none-alternation porphyry, show inheritance directly from initial magma. Sulfides delta(34) S-VCDT (1. 96 parts per thousand to +1.99 parts per thousand) are coincidence with delta S-34 in porphyry deposits of low oxygen fugacity. This research gives objective and reasonable explanation on metallization mechanism of Laochang Mo-deposit, and provide example for Cenozoic porphyry-skarn system in Sanjiang Tethys.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2099
EP 2114
UT WOS:000408702200009
ER  

PT J
AU Liu, JY
Deng, J
Li, GJ
Xiao, CH
Meng, FJ
Chen, FC
Wu, W
Zhang, QW
AF Liu JinYu
Deng Jun
Li GongJian
Xiao ChangHao
Meng FuJun
Chen FuChuan
Wu Wei
Zhang QiWei
TI Petrogenesis and tectonic significance of the Lianhuashan intrusion in the Lanping Basin, western Yunnan: Constraints from bulk element composition, zircon U-Pb geochronology and Hf isotopic compositions
SO ACTA PETROLOGICA SINICA
AB The Cenozoic intra-continental potassic magmatic belt along the Jinshajiang-Ailaoshan Paleo-Tethyan suture zone has been a hot issue in geological research, whereas the igneous rocks in the Indo-China Block, west to Jinshajiang-Ailaoshan potassic magmatic belt have been rarely investigated, restricting a deeper insight into the formation of this potassic magmatic belt and the architecture of crust-mantle underneath the Indo-China Block. In this paper, we carry out a systematic study of the petrography, whole rock geochemistry, zircon U-Pb dating and Hf isotope for the Lianhuashan intrusion, which is located in the southeast of the Lanping Basin, the northern part of the Indo-China Block. Our results demonstrate that the Lianhuashan intrusion is mainly composed of quartz monzonite porphyries. LA-ICPMS zircon U-Pb dating shows that the Lianhuashan intrusion was emplaced at similar to 34Ma. The rocks show shoshonitic affinity, with high total alkali (Na2O + K2O =9. 0% similar to 9. 2%), and potassium (K2O/Na2O = 1. 0 similar to 1. 2). They are also enriched in LILEs (Th and U) and LREEs ( (La/Yb)(N) = 22 similar to 24), but relatively depleted in HFSEs (Nb and Ta). Based on the above-mentioned data, it is suggested that the magmas for the Lianhuashan intrusion were derived from an enriched source region ever metasomatized by oceanic slab subduction. Zircon epsilon(Hf)(t) values range from + 1. 4 to + 4. 6, mostly clustering between + 2. 8 and + 4. 0, corresponding to Hf crust model ages (t(DM2)) ranging from 1027Ma to 815Ma and mainly clustering between 934Ma and 860Ma. The narrow range of zircon epsilon(Hf) (t) values and lack of inherited zircons preclude assimilation of wall rocks during the magma ascent. As currently known, since Neoproterozoic ( < 1000Ma), the Indo-China Block had been merely subducted by the Jinshajiang-Ailaoshan Paleo-Tethyan ocean during Permian (ca. 290 similar to 250Ma). Neoproterozoic Hf crust model ages demonstrate an input of terrigenous sediments into mantle during the Paleo-Tethyan slab subduction, which is consistent with Nb/U ratio (1. 3 similar to 4.7) of the Lianhuashan intrusion. The Lianhuashan intrusion, the Zhuopan potassic mafic complex to the west of the Lianhuashan intrusion, and potassic rocks in the western Yangtze block, together constitute a part of the Jinshajiang-Ailaoshan potassic magmatic belt, which was triggered by upwelling asthenosphere after delamination of lithosphere underneath the Paleo-Tethyan suture. This tectonic-thermal event, which gave rise to the formation of the Lianhuashan and the Zhuopan intrusion, is suggested to have influenced westwards to the interior of the Indo-China Block, spatially more broadly than previously believed.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2115
EP 2128
UT WOS:000408702200010
ER  

PT J
AU Zhang, PF
Li, GJ
Huang, YH
Liang, K
Yang, JB
Liu, YC
Mao, FX
Zhao, F
AF Zhang PengFei
Li GongJian
Huang YuHan
Liang Kun
Yang JinBiao
Liu YunCheng
Mao FuXiang
Zhao Feng
TI Metallogenic process of Laochang Pb-Zn polymetallic VMS deposit in Sanjiang orogenic belt, SW China: Evidenced from fluid inclusion and sulfur isotope
SO ACTA PETROLOGICA SINICA
AB The Laochang Pb-Zn polymetallic massive sulfide deposit is the only-one discovered deposit which is genetically related to the hosted OIB-type volcanic rocks in the Sanjiang Tethys orogenic belt, SW China. The characteristics and sources of the ore-foming fluids and metals, and the metallogenetic process are still debated and therefore worthy of study. Based on the field work and microscope study on the massive orebodies and stockworks mineralization of the No. I ore group, some typical calcites from the massive orebodies and quartzes from the stockworks mineralization are selected for fluid inclusions study, and some sulfides from the main types of ores are picked for sulfur isotope analysis. The results show that the primary fluid inclusions of the two type' s orebodies belong to NaCl-H2O system. The metallogenetic temperature of massive ores is 110 similar to 158 degrees C and salinity is 13. 2% similar to 18. 7% NaCleqv. By contrast, the metallogenetic temperature of stockwork ores is 186 similar to 371 degrees C, clustering at 246 similar to 339 degrees C, and salinity is 3. 6% similar to 19. 8% NaCleqv, clustering at 6. 7% similar to 16. 8% NaCleqv. The reducing of metallogenetic temperature from the lower stockwork mineralization to the upper massive orebody reflects the process of high temperature metallogenetic hydrotherm rised to seafloor along the venting channels and cooled down with seawater. During the process, the salinity of fluid does not display significant decline, which imply the exist of high salinity brine on the seafloor before mineralization. The delta S-34 values of various types are almost same, range from 0. 69 parts per thousand to 1. 32 parts per thousand, stable composition (range only 2. 01 parts per thousand) and near zero. Symbiotic sulfides have a trend of delta(34) S-pynte >Sphalerite >galena indicating that the sulfur isotope basically reach the fractional equilibrium. The delta S-34 of sulfide ores concentrated in Zero is different from significant positive delta S-34 caused by the inorganic reduction of seawater sulfate, and also different from significant negative es caused by the reduction of organic (bacteria). Therefore, the sulfur is derived from the basic volcanic rocks beneath orebodies, through leaching of magmatic sulfides in the footwall volcanic rocks or directly from magmatic degassing. Based on the results of precious study of the CH-O-Pb isotopic compositions, it is considered that the magmatic degassing occurred during the formation of Laochang VMS-type deposit, which provides sulfur, mineralization metals and the initial metallogenetic fluids.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2129
EP 2142
UT WOS:000408702200011
ER  

PT J
AU Zhou, Y
Hou, ZQ
Zheng, YC
Xu, B
Wang, R
Luo, CH
AF Zhou Ye
Hou ZengQian
Zheng YuanChuan
Xu Bo
Wang Rui
Luo ChenHao
TI Granulite xenoliths in Liuhe area: Evidence for composition and genetic mechanism of the lower crust from the Neoproterozoic to Cenozoic
SO ACTA PETROLOGICA SINICA
AB Liuhe area locates in western edge of Yangtze Craton, and the composition and genetic mechanism of deep crust are still unkown. The deep xenoliths, entrained by Liuhe Cenozoic mantle-derived intrusion, provide direct evidence of formation and genetic mechanism of the lower crust of Liuhe area. The xenoliths are high-grade orthometamorphite (granulite facies), including garnet pyroxenite, garnet amphibole-pyroxenite and garnet amphibolite. The xenoliths have SiO2 contents of 43. 85% similar to 50. 82%, high MgO contents of 6. 83% similar to 14. 77%, Mg-# ratios of 0.50 similar to 0. 64, Cr contents of 87. 1 x 10(-6) similar to 616 x 10(-6) Ni contents of 19.7 x 10(-6) similar to 143 x 10(-6), suggesting these xenoliths belong to low-Mg garnet cumulates. Based on the garnet-clinopyroxene Fe-Mg geothermometer calculations, crystallization of garnet amphibolite occurred at temperatures of 721 similar to 774 degrees C and depth of 45 similar to 47km. The crystallized temperatures of garnet pyroxenite and garnet amphibole-pyroxenite are 803 similar to 829 degrees C at depth of 48 similar to 51km. These data indicate garnet amphibolite, garnet pyroxenite and garnet amphibole-pyroxenite were formed in lower crust. Zircons of the xenoliths are mainly metamorphic zircons, and can be divided into two groups. Their U-Pb ages are 259 +/- 9Ma with kappa(Hf) (t) ratios of -5. 69 similar to 10. 3, and 773 +/- 23Ma with epsilon(Hf) (t) ratios of 5. 87 similar to 17.7. The Sm-Nd isochron ages give two populations at 251 similar to 4Ma and 809 +/- 64Ma, respectively. These age data indicatee the lower crust of Liuhe area underwent both magmatic underplating and metamorphism in the Neoproterozoic and late Permian respectively. The Neoproterozoic xenoliths show enrichment of LILE and significant depletion of HFSE, and have epsilon(Nd) (t) ratios of 4. 36 similar to 5.28. These are typical characteristics of arc magmas derived from the mantle wedge, and the batching melting calculations indicate the magmas were formed by 10% similar to 30% partial melting of garnet-spinel peridotite. Late Permian xenoliths show enrichment of LILE and weak depletion of HFSE, and have epsilon(Nd) (t) raitos of -5. 68 to +2. 33, suggesting these xenoliths were derived from plume-lithosphere interaction, and the batching melting calculations indicate the magmas were formed by melts derived from 10% similar to 20% partial melting of garnet-spinel peridotite. In a word, the lower crust of Liuhe area, due to subduction in the Neoproterozoic and plume-lithosphere interaction in Late Permian respectively, underwent the mantle-derived material input and became mafic juvenile lower crust.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2143
EP 2160
UT WOS:000408702200012
ER  

PT J
AU Gao, X
Meng, JY
AF Gao Xue
Meng JianYin
TI The source of ore-forming fluids and materials in the Tongchanggou Mo-Cu deposit, northwestern Yunnan, China: Constrains from skarn mineralogy and stable isotopes
SO ACTA PETROLOGICA SINICA
AB Yidun Terrane is located in the northern-central segment of Sanjiang Tethys metallogenic domain, developing massive Late Triassic and Late Cretaceous felsic magmatism and related porphyry-skarn Mo-Cu-polymetallic mineralization The Tongchanggou deposit is a newly discovered porphyry-skarn type Mo-Cu deposit in the southern Yidun Terrane, with proven reserves of 142. 5Mt. Skarn extensively exposed in the Tongchanggou district, with skarn-type ore being the most important ore type. Based on the mineral assemblages and paragenesis, Tongchanggou skarn can be divided into garnet skarn, diopside skarn and tremolite skarn. Detailed adit mapping and drill-hole logging suggest that the skarn mineralogy at Tongchanggou is controlled by the spatial distribution of granodiorite and marble: 1) it develops diopside skarn -> tremolite skarn -> garnet skarn upward or downward from the marble, 2) the grain size of garnet turns to be larger from top to bottom along the drill-hole, and 3) Mo-Cu mineralization is associated with retrograde altered minerals such as tremolite and epidote, thus orebody usually develop in the outer contact zone between granodiorite and marble. The dominant garnet at Tongchanggou occurs as euhedral grain or granular aggregates, and is dark and isotropical. The compositions of garnet are mainly grossularite (62.2 similar to 78.3), followed by andradite (16.7 similar to 34.2), with minor spessartite, almandine and pyrope. The Fe-2/Fe3+ ratios of garnet from Tongchanggou deposit are varying from 0.00 to 0.20, with an average value of 0.06, indicating a relatively oxidative environment for the formation of garnet. The delta(18) O-SMOW, values of garnet are ranging between 5.2 parts per thousand and 9.5 parts per thousand, indicating that skarn might have directly inherited the oxygen isotope compositions of granodiorite. Additionally, sulfides are characterized by uniform S-Pb isotopes, with delta(34) S-(CDT) values of 0. 7 parts per thousand similar to 1. 4 parts per thousand, Pb-206/Pb-204 ratios of 18. 332 similar to 18. 694, Pb-208/Pb-204 ratios of 38. 454 similar to 39. 088, and Pb-207/(204) Pb ratios of 15. 588 similar to 15. 663, indicating that the ore-forming fluids and materials of Tongchanggou deposit originated from crust-derived felsic magmas.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2161
EP 2174
UT WOS:000408702200013
ER  

PT J
AU Bao, XS
He, WY
Gao, X
AF Bao XinShang
He WenYan
Gao Xue
TI The Beiya gold deposit: Constraint from water-rich magmas to mineralization
SO ACTA PETROLOGICA SINICA
AB The Beiya gold deposit is the biggest Cenozoic gold deposit in the Jinshajiang-Ailaoshan porphyry metallogenic belt, with gold reserve more than 320t. The study of the petrography and geochemical features of the Beiya monzogranite porphyry presented in this paper shows that the Beiya monzogranite porphyry is characterized by amphibole phenocrysts, with high Sr (>300 x 10(-6)), low Y (< 10 x 10(-6)) and high (La/Yb)(N) (6. 19 similar to 26. 8) values, which indicates that amphibole crystalizes in early magmatic differentiation. The presence of amphibole during the early stages of crystallization indicates that the Beiya ore-related magma were very hydrous melts. At the same time, the contents of amphibole suggest that the water contents of the Beiya melts are varying between 3. 8% and 4. 1%, which further confirmed Beiya ore-related magma is relatively water-rich. During the process of partial melting in the source of the Beiya gold deposit, the addition of H2O can reduce the melting point of magma, promote remelting of the source containing copper, gold sulfide, or extraction of copper, gold ore-forming elements from rock, or gather the scattered distribution of metal elements in magma, forming metal-rich magma. After the emplacement of the Beiya ore-related magma, through the pressure decrease to reduce the water solubility, or by magma crystallization increasing the water contents of the Beiya melts, prompted the magmatic water earlier reached saturation and dissolved fluid. Then providing main ore-forming fluids and metal source for the porphyry mineralization and generating (or improving) the metallogenic potential of the Beiya water-rich magma. In general, the water-rich magma in the Beiya gold deposit not only plays an important role during the process of ore-fluid formation, but also the components of Cu, Au and other metal of the ore-forming fluid.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2175
EP 2188
UT WOS:000408702200014
ER  

PT J
AU Li, HJ
Wang, QF
Yang, L
Yu, HZ
Wang, X
AF Li HuaJian
Wang QingFei
Yang Lin
Yu HuaZhi
Wang Xuan
TI Orogenic gold deposits formed in Tibetan collisional orogen setting: Geotectonic setting, geological and geochemical features
SO ACTA PETROLOGICA SINICA
AB There are two orogenic gold belts: Yarlung Zangbo suture zone and Ailaoshan orogenic belt, formed in Tibetan collisional orogenic setting. Orogenic gold deposits formed on the Yarlung Zangbo suture zone include Mayum, Nianzha, Bangbu and Zhemulang gold deposit, etc. This gold belt formed in compression structural setting in which the crust of Lhasa Terrane and Tethyan Himalaya Sequence shortened and thickened at the beginning of Tibetan collisional orogen (59 similar to 44Ma). It is coeval with Linzizong volcanic rock and high-pressure metamorphic rocks. Orogenic gold deposits on the belt are controlled by EW-striking structure. Gold is concentrated as native gold in sulfide-quartz veins, as well as in greenschist facies host rocks surrounding sulfide-quartz veins, mainly as slate and phyllite. Orogenic gold deposits formed on the Ailaoshan orogenic belt include Zhenyuan, Jinchang, Daping and Chang' an gold deposit, etc. These deposits mainly formed in 35 similar to 26Ma, dominated by large strike-slip faults in the district. They are controlled by NW-SE striking structure and the metamorphic grade of the lithologies surrounding the Ailaoshan orogenic gold deposits is lower than the Yarlung Zangbo' s. Cenozoic lamprophyre and alkali rich porphyry formed during the early mineralization distribute wildly in the ore district. C-S-H-O-Pb isotopes vary widely between deposits. Ore-forming fluids of the Yarlung Zangbo suture zone and Ailaoshan orogenic belt mainly derived from deep reduced mantle fluids, metamorphic fluids coming from dehydration of host stratum and magmaic fluid. The different lithology of host rocks can also cause the variability of isotope compositions.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2189
EP 2201
UT WOS:000408702200015
ER  

PT J
AU Yu, HZ
Wang, QF
Li, JR
Cheng, L
Zhang, YJ
AF Yu HuaZhi
Wang QingFei
Li JianRong
Cheng Lin
Zhang YuJie
TI Metallogenesis of the Mengman hot-spring type gold deposit, southern Lancangjiang zone: Constraints by hydrothermal alteration and trace element composition
SO ACTA PETROLOGICA SINICA
AB Mengman gold deposit is one of the few hot-spring type gold deposits in Sanjiang Tethys orogen, as well as the only one in the southern Lancangjiang zone. However, it restricts the further comprehension of the metallogenic process that there is not enough analysis of hydrothermal alteration and the absence of geochemical data. The primary ore bodies of Mengman gold deposit exist around the unconformity between the Early-Paleozoic Manlai schist of Lancang Group and Jurassic Huakaizuo elastic rocks, the fault structure of which plays an important role in fluid-directing and ore-controlling. Both the two types of wall-rocks have experienced intensive hydrothermal alteration, while the alteration type is not complicated, only silication and kaolinization, and they are closely related to gold mineralization. The hydrothermal kaolinization reflects that it is the acid fluid that reacted with feldspars of wall-rocks. Comparison among whole-rock trace element composition indicates no obvious trace element migration, and the positive correlation trend between Au and Ag, Cu, Pb, As, S, Sb means these elements are in the same hydrothermal system, combined with gold existing with metal sulfides such as chalcopyrite. Meanwhile, Au mainly exists as Au(HS)(2) (-) in the faintly acid ore-forming fluid. When the fluid arrived in the unconformity, it reacted with the wall-rocks, with strong hydrothermal kaolinization, contributing to the rapid increase of quartz and kaolinite in the fluid. Moreover, the increase caused precipitation of quartz and kaolinite, resulting in the fault becoming narrow and the pressure gradually arising, and eventually causing the explosion, which directly leads to the boiling of the ore-forming fluid and the precipitation of the gold. It repeatedly happened, therefore the gold-bearing siliceous breccia and altered rock type ores are finally formed.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2202
EP 2212
UT WOS:000408702200016
ER  

PT J
AU Wang, CG
Yang, LQ
He, WY
AF Wang ChenGuang
Yang LiQiang
He WenYan
TI Apatite trace element and halogen compositions from the Beiya gold deposit, in western Yunnan and geological significance
SO ACTA PETROLOGICA SINICA
AB The Beiya porphyry gold-polymetallic deposit located in western Yunnan is the largest gold polymetallic deposit of Cenozoic Jinshajiang-Ailaoshan alkali-rich porphyry metallogenic belt. It' s proven gold reserves have exceeded 350t, and associated copper, lead and zinc, iron, silver, sulfur have reached medium-large scale. Abundant previous studies have focused on the genesis of Beiya deposit, but some controversies still remain regarding the relationship between alkali-rich porphyry diagenesis and gold-polymetallic mineralization. In this study, the major and trace element of apatite from the Beiya ore-bearing and ore-barren alkali-rich porphyries were analyzed, and their compositional differences would throw light on the diagenetic and mineralized information recorded in apatite. The results show that all apatites from the ore-bearing and barren monzogranite porphyries are rich in F ( most of them > 2%) and lack of Cl (most of them <0. 02%), and F versus Cl display a relatively negative correlation. The apatites from ore-bearing porphyries have a relatively higher delta Eu and obviously lower delta Ce, indicating that the oxygen fugacity of ore-bearing porphyries is higher than barren porphyries. The high oxygen fugacity is favorable of mineralization because it can refrains the formation of Fe-bearing sulfides, store the metal elements and release more Cu, Au elements in the source. Meanwhile, the exsolution of Cl-bearing hydrothermal fluids caused the decrease of (Sm/Yb)(N) in apatites from the Beiya porphyries. Compared to apatites from the Beiya ore bearing porphyries, apatites from the Beiya barren porphyries have lower Ce/Pb and higher Th/U, and this reflects that the fluid activity of barren porphyries is weaker, leading to inconspicuous magmatic differentiation. It is also suggested that F/Cl in apatite from the ore-bearing porphyries could constrain the tectonic setting of porphyry deposits. For example, the F/Cl of apatites from the Beiya and Yulong ore-bearing porphyries are much higher than that from the Pulang, Chundu and Tongchanggou ore-bearing porphyries. In this case, the former were considered to be formed in intracontinental collisional environment, while the latter were formed in the typical subducted setting.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2213
EP 2224
UT WOS:000408702200017
ER  

PT J
AU Zhu, FL
Bai, M
Tao, Y
AF Zhu FeiLin
Bai Mei
Tao Yan
TI Lithogeochemical characteristics and metallogenic mechanism of the Hetaoshu rich-PGE magmatic sulfide deposit in the Xiaoguanhe region, Panxi
SO ACTA PETROLOGICA SINICA
AB The Hetaoshu rich-PGE magmatic sulfide deposit is located in Xiaoguanhe area, Huili County, the ore-bearing lithofaciy is a mafic-ultramafic intrusion, which is one of the magma sulfide deposits rich in PGE content in the Emeishan Large Igneous Province (ELIP). This paper will provide a basic study on major elements, trace elements and platinum-group elements for various rocks and ores in the intrusion, and we discussed the characteristic of magma source and parental magma, the degree of partial melting of the mantle, and the process of rock-forming and ore-forming. The study show that the Hetaoshu mafic-ultramafic rocks are products of tectonic-magmatic activity in the ELIP and belong to tholeiitic evolution trend, which have the similar characteristics with Emeishan basalts from the ratio of the trace elements. Primitive mantle-normalized patterns of Ni-Cu-PGE are similar with Jinbaoshan with the low ratio of Pd/Ir (1.5 similar to 13. 1), relative to the Ni and Cu, PGE is undepletion, relative to Os, Ir,, Ru and Rh, Pt and Pd are enrichment. By estimating, the parental magma was produced by fractional crystallization from picritic-like magmas generated by relatively high degrees (about 20. 17%) of partial melting of an OIB-type mantle source, with the composition of 11. 93% in MgO, 49. 88% in SiO2, 2. 61% in TiO2 and 13. 71% in FeOT. In comparison with several types of Ni-Cu-PGE magmatic sulfide deposits from the composition of PGE and sulfide segregation in the Xiaoguanhe area, the enrichment of platinum group elements and low of Cu/ Pd of the Hetaoshu deposit is similar with Jinbaoshan, this kind of characteristic indicated that, the sulfide might segregate from the PGE undepleted picritic-like magmas. By analysis of the mechanism of diagenesis and mineralization, in the early stage of magmatic evolution, the accumulation of mafic minerals which represented as olivine (about 12. 7%) occurred after the picritic-like magmas intruded deep-level chamber, and formed high-Mg basalt magma; affected by factors such as temperature reduction and crustal contamination, the partial residual high-Mg basaltic magma have undergone segregation (R = 2000 similar to 50000) when they flowed from deep to high level chamber; then the sulfide melt mixed with olivine, which form in magma conduit. Finally, under the impacts of tectonic compression, the olivine-sulfide mixtures formed rich-PGE intrusion by accumulation in high-level chamber, its highly variable R factor are corresponding with the wide range of PGE contents.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2225
EP 2240
UT WOS:000408702200018
ER  

PT J
AU Chen, XY
Liu, JL
Qi, YC
Fan, WK
Ling, CY
AF Chen XiaoYu
Liu JunLai
Qi YinChuan
Fan WenKui
Ling ChengYang
TI Deformation characteristics of the granitic rocks from the mid-crustal shear zone and constraints on the tectono-magmatic relationship: Exemplified by the Diancang Shan complex, western Yunnan
SO ACTA PETROLOGICA SINICA
AB The shearing duration of the Ailao Shan-Red River (ASRR) shear zone has been debated over the years. The essence of this controversy is rooted in the relationship between the shearing and the magmatism in or near the shear zone. Diancang Shan complex lies in the north part of the ASRR shear zone, and is composed of three parts, i. e., the western high-grade metamorphic rocks, the eastern superimposed retrogressive metamorphism belt, and varying ages of magmatic rocks. In order to better constraint pre-,syn- and post-shearing granitic veins, the relationship between deformation and magmatism during shearing, and the initiation time of the shear zone, this study has carried out detailed macro- and micro-structural analyses and fabric study, which are helpful to reveal the flow structure and crystal plastic deformation structure, and also zircon U-Pb dating of granitic veins of syn-shearing. The results show that different stages of granitic rocks have different macro- and micro-structure and fabric features. Two zircon U-Pb ages of syn-shearing at 28. 54 +/- 0. 15Ma and 27. 31 +/- 0. 23Ma are dated. 28. 54 +/- 0. 15Ma represents the early shearing time, and 27. 31 +/- 0. 23Ma represents the late shearing age. This study reveals that the late shearing vein ( the latter) is located in the high strain zone of progressive shearing and possesses more complex deformation structure, microstructure and fabric type, however, the early shearing vein ( the former) in the low strain zone of progressive shearing has a simple structure, microstructure and fabric type, and still has the characteristics of magma crystallization fabric. ASRR shear zone experienced a progressive shearing of a higher temperature deformation in the early stage ( similar to 700 degrees C), medium-high temperature deformation in the middle stage (550 similar to 600 degrees C) and low temperature deformation in the late stage (lower than 400 degrees C) from 28. 54Ma to 27. 31Ma.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2241
EP 2255
UT WOS:000408702200019
ER  

PT J
AU Zhang, BL
Shan, W
Li, DP
Xiao, BJ
Wang, ZL
Zhang, RZ
AF Zhang BingLin
Shan Wei
Li DaPeng
Xiao BingJian
Wang ZhongLiang
Zhang RuiZhong
TI Hydrothermal alteration in the Dayingezhuang gold deposit, Jiaodong, China
SO ACTA PETROLOGICA SINICA
AB Jiaodong is the most important gold ore-concentrated region of China. And the fracture zone altered-type gold deposit which named "Jiaojia-type" gold deposit, is the most important gold deposit type of the region, which takes up over 90% the proven amount of gold. Dayingezhuang gold deposit which located in the middle of the Zhaoping gold belt, is a typical fracture zone altered type gold deposit with large-scale sericite-quartz alteration zone (with the width of 20 similar to 200m) and K-feldspar/reddish alteration zone (with the width of 50 similar to 300m) occur in the gold deposit. And the altered rock type gold orebody mainly develops in the sericite-quartz alteration zone which is in the footwall of Zhaoping fault zone. Based on the detailed geological observations in the field, we found out the alteration type and mineral assemblage of the Dayingezhuang gold deposit, collected different types of alteration rock samples in the II orebody scientifically, conducted rock geochemistry element analysis, which is using the method of the mass balance to discuss the regularity of elements migration in the hydrothermal alteration process and mechanism, discussed the mechanism of gold precipitation. We conclude that the hydrothermal alteration can be devided into K-feldspar/reddish alteration, sericite-quartz alteration, pyrite-sericite-quartz alteration, and carbonatization. K-feldspar/reddish alteration occurred in the premineralization, some K-feldspar can be formed during this process. Fe, Cu, Pb, Rb are brought into wall-rock, while Si, Al, Na, Ca, Ba, Sr, Cr are brought out in geochemistry aspect. At the same time, the Au are released into ore-forming fluid because of the interaction between fluid and wallrock. Sericite-quartz alteration and pyrite-sericite-quartz alteration occurred during the mineralization, with the enhancement of alteration, Fe, Cu, Pb and other elements related to mineralization are enriched during alteration, the descent of the content of HS- induced the decomposement of Au (HS)(2-), Fe2+ and Fe3+ were consumed to form the pyrites, which induced the deposition and enrichment gold. Gold activate, migrate and deposit through all these process.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2256
EP 2272
UT WOS:000408702200020
ER  

PT J
AU Liu, Y
Zhang, L
Sun, SC
Wu, SG
Gao, L
AF Liu, Y.
Zhang, L.
Sun, S. C.
Wu, S. G.
Gao, L.
TI Mineralization mechanism of Yangshanzhuang gold deposit, northeastern Hunan Province
SO ACTA PETROLOGICA SINICA
AB The Yangshanzhuang gold deposit, located in the middle part of the Jiangnan orogenic belt, is hosted by the Neoproterozoic low-grade metamorphic sericite slate and silty slate and is strictly controlled by NW-NWW-trending faults. According to intergrowth and crosscutting relationships among different minerals, three paragenetic stages were identified, which are quartz-arsnopyrite-pyrite-native gold-scheelite-dolomite-muscovite (stage I); quartz-arsnopyrite-pyrite-native gold-chalcopyrite-galena-sphalerite-sericite (stage II) and quartz-sericite (stage III). Fluid inclusions in stage I and II are mainly aqueous inclusions with minor gaseous inclusions and H2O-CO2 inclusions. Raman spectroscopy analysis indicates that gaseous inclusions are consist of N-2, CH4 and CO2. Mineralization temperature and salinity of the ore-forming fluid are restricted in ranges of 240 similar to 320 degrees C and 7% similar to 9% NaCleqv, respectively. The combined microthermometry and Raman spectroscopy studies suggest a H2O-NaCl-CO2 fluid system characterized by medium-low temperature and medium-low salinity. Fluid phase separation occurred during the process of wall rock metasomatism in Stage I and Stage II. The concentration of liquidus CO2 decreased because of phase separation might further facilitate the deposition of gold.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2273
EP 2284
UT WOS:000408702200021
ER  

PT J
AU Li, J
Sun, ZB
Xu, GX
Tian, SM
Deng, RH
Zhou, K
AF Li, J.
Sun, Z. B.
Xu, G. X.
Tian, S. M.
Deng, R. H.
Zhou, K.
TI P-T-t path and geological significance of retrograded eclogites from Mengku area in western Yumumn Province, China
SO ACTA PETROLOGICA SINICA
AB Early balanced paragenetic mineral assemblage in retrograded eclogites, which underwent more period remetamorphism, from Mengku area, Shuangjiang County of western Yunnan Province, is hardly found. It is uncertain to estimate pressure and temperature in early metamorphism by means of traditional garnet-clinopyroxene geothermometer and garnet-clinopyroxene-phengite geobarometer. In this article, the authors study compositions change of phengite, garnet and omphacite in the P-T pseudosection, which is calculated by Wei et al. (2009) based on MORB, with pressure and temperature change. By this way, the authors obtain P =2. 00 similar to 2. 30GPa and T =420 similar to 460 degrees C in the prograde metamorphism, P = 3. 35 similar to 4.46GPa and T = 530 similar to 610 degrees C in the peak period metamorphism, P = 2. 00 similar to 2. 50GPa and T = 470 similar to 540 degrees C in the early period remetamorphism, P = 0. 95 similar to 1. 43GPa and T = 700 750 degrees C in the medium period remetamorphism, they are respectively equivalent to lawsonite blueschist facies to lawsonite-glaucophane eclogite facies, lawsonite eclogite facies, lawsonite-glaucophane eclogite facies and hornblend eclogite facies to high pressure granulite facies. Late period remetamorphism is characterized by a plenty of amphibolites. It can be divided three stages, and shows the continued cooling and pressure reduction process. Based on the research for regional crust' s revolution, author discusses geological significances of the P-T-t path in detail.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2285
EP 2301
UT WOS:000408702200022
ER  

PT J
AU Chen, J
Gong, QJ
Wang, JH
Chen, L
Yan, TT
He, XY
Li, JZ
AF Chen, J.
Gong, Q. J.
Wang, J. H.
Chen, L.
Yan, T. T.
He, X. Y.
Li, J. Z.
TI Determination indicator elements for geochemical exploration on rock and soil survey in Huaishuping gold deposit in western Henan Province, China
SO ACTA PETROLOGICA SINICA
AB Huaishuping gold deposit is a large-scale gold deposit discovered recently in Xiong' ershan district in western Henan Province, China. Different types of fresh host rocks, alteration rocks and ores are collected on the surface and under the pit in Huaishuping deposit area and soil geochemical survey is fulfilled with a scale of 1 : 20000. 29 trace elements including Au are analyzed in rock and soil samples. Lower anomaly limit of each trace element is determined on fresh host rocks. Average of each trace element in alteration rocks and ores is derived respectively to calculate its anomaly contrast which is the ratio of its average in alteration rocks or ores to its lower anomaly limit in fresh host rocks. The element, which anomaly contrast is larger than 1. 4, is selected as the indicator element for gold mineralization in the first step. On the other hand, the scatter plots of Au to the other 28 trace elements in fresh host rocks, alteration rocks and ores are illustrated to determine indicator elements for gold mineralization. The results of the two methods indicate that indicator elements of rock geochemical prospecting are Au, Ag, As, Sb, Hg, Sn, Mo, Bi, Cu, Pb, Zn, Cd, and Nb (13 items) in Huaishuping gold deposit. Geochemical anomaly maps are drawn on the soil survey results in Huaishuping district using 1. 4 anomaly contrasts in rock samples as lower anomaly limits in soil samples. Jigongshan ore section, which is the main ore section in Huaishuping gold deposit, is selected as a model area to determine the indicator elements and the results show that indicator elements of soil geochemical prospecting are Au, Ag, As, Sb, Hg, Bi, Cu, Pb, Zn, Cd, and B (11 items). Comparing the indicator elements between rock and soil survey samples, inheritance on indicator elements is inferred from rocks to soils during weathering. 10 common indicator elements in rock and soil samples are selected to construct a comprehensive anomaly index. The whole area of Huaishuping gold deposit is evaluated on the comprehensive anomaly index. The evaluation results show that 4 other sections, Matigou, Qinfoyegou, Jianggeda, and Tianpingxi, have similar mineral potential to that of Jigongshan ore section in Huaishuping area.
SN 1000-0569
EI 2095-8927
PD JUL
PY 2017
VL 33
IS 7
BP 2302
EP 2312
UT WOS:000408702200023
ER  

EF  

黔ICP备07002071号-2
主办单位:中国矿物岩石地球化学学会
印刷版(Print): ISSN 1000-0569 网络版(Online): ISSN 2095-8927
单位地址:北京9825信箱/北京朝阳区北土城西路19号
本系统由北京勤云科技发展有限公司设计

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