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PT J
AU Xu, ZQ
Zhao, ZB
Peng, M
Ma, XX
Li, HQ
Zhao, JM
AF Xu ZhiQin
Zhao ZhongBao
Peng Miao
Ma XuXuan
Li HuaQi
Zhao JunMeng
TI Review of "orogenic plateau"
SO ACTA PETROLOGICA SINICA
AB Plateaus on earth can be subdivided into two categories: craton plateau and orogenic plateau. Craton plateau normally developed on Precambrian basement or stable craton, which is characterized by simple, homogeneous, stable, cold and strong old basement, such as Brazilian Plateau, Colorado Plateau, Ethiopia Plateau, South African Plateau, Middle Siberia Plateau, Deccan Plateau, and so on. Basement of orogenic plateau is always composed by different orogenic units. The orogenic plateau could be separated into subducted orogenic plateau and collisional orogenic plateau two groups. The Middle Andean Plateau, formed overlying eastward subducted Pacific plate, belongs the subducted orogenic plateau. While, the Tibetan Plateau possess complex and uninformed soft basements which have experienced multiple phase orogeny. New research results illustrate that the Tibetan Plateau begin uplifted during Early Cretaceous, it may be related with closure of Bangong-Nujiang Ocean at 120 similar to 140Ma. However, India-Asian collision (60 similar to 50Ma) and concomitantly low angle under thrust of Indian lithosphere beneath Tibetan Plateau lead to the Plateau finally elevated over 4000 similar to 5000m.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3557
EP 3571
UT WOS:000391345300001
ER  

PT J
AU Wang, YY
Gao, LE
Zeng, LS
Chen, FK
Hou, KJ
Wang, Q
Zhao, LH
Gao, JH
AF Wang YaYing
Gao LiE
Zeng LingSen
Chen FuKun
Hou KeJun
Wang Qian
Zhao LingHao
Gao JiaHao
TI Multiple phases of cretaceous mafic magmatism in the Gyangze-Kangma area, Tethyan Himalaya, southern Tibet. 2016
SO ACTA PETROLOGICA SINICA
AB A large number of E-W trending subparallel diabases occurred in the Gyangze-Kangma area, eastern Tethyan Himalaya, southern Tibet. Results from field observation, zircon U-Pb dating, whole-rock geochemical and Sr-Nd isotopic data indicate that they represent at least three episodes of Cretaceous mafic magmatism within the Tethyan Himalaya at similar to 140Ma, similar to 120Ma, and similar to 90Ma, respectively. (1) The T0907 suite, occurred at 142. 0 +/- 1. 4Ma, is characterized by OIB-like trace element patterns and Sr-Nd isotopic compositions, similar to those in the similar to 132Ma Comei-Bunbury Large Igneous Province to the east. However, the contemporaneous T0902 suite shows elevated Mg, Cr and Ni contents, but Nb-Ta negative anomalies, Pb positive anomalies and negative epsilon(Nd)(t) values, which could be derived from an enriched lithospheric source; (2) The T0904 suite, formed at 121. 1 +/- 0. 7Ma, displays N-MORB-like geochemical characteristics; (3) The T0901 suite, formed at similar to 90Ma, displays E-MORB-like geochemical characteristics. Combined with the evolutional history of the breakup of the East Gondwana continent and the hotspot track of the Kerguelen mantle plume, we suggest that the mafic magmatism at similar to 140Ma in Gyangze-Kangma area represents the products from interaction between the Kerguelen mantle plume and the overlying East Gondwana continental lithospheric mantle, possibly due to relatively long-time incubation of the Kerguelen mantle plume beneath the East Gondwana supercontinent. However, with the breakup of the East Gondwana continent and the initiation and spreading of the Indian oceanic ridge, the Indian continent started to drift away from the Kerguelen hotspot. Mafic magmatism at similar to 120Ma and similar to 90Ma in this studied area represent the products formed by partial melting of asthenosphere mantle under Indian ridges, rather than the products of Kerguelen mantle plume. Data presented above indicates that mafic rocks within the Himalayan terrane were produced by multiple episodes of magmatism associated with the breakup of the East Gondwana continent and the intitiation and spreading of the Indian Ocean since similar to 140Ma. These mafic rocks formed at different times provide important time frames for paleomagentic studies and further constrains on the tectonic history of the Himalayan orogenic belt.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3572
EP 3596
UT WOS:000391345300002
ER  

PT J
AU Yu, SB
Qiu, JS
Wang, RQ
AF Yu SiBin
Qiu JianSheng
Wang RuiQiang
TI Petrogenesis of the Daju composite granite pluton in the middle segment of the Gangdese belt: Constraints from zircon U-Pb ages, elemental geochemistry and Hf isotopes
SO ACTA PETROLOGICA SINICA
AB This paper presents comprehensive zircon U-Pb ages and Hf isotopic compositions, and whole-rock geochemistry for the Daju composite granite pluton in the middle segment of the Gangdese belt, with the aims of elucidating the formation mechanism and evolution process of their magmas, and gaining new insights into their petrogenesis. According to the lithological and petrographic characteristics, this pluton can be divided into two units, i.e., the Changna (CN) unit and the Sangga (SG) unit. The CN unit consists mainly of granodiorites with abundant dioritic enclaves, while the SG unit is composed of medium to fine-grained monzogranites with generally homogenerous lithology. Zircon LA-ICP-MS U-Pb dating yields coeval ages of 52. 7 +/- 0. 7Ma for the granodiorites and of 52. 3 +/- 0. 6Ma for the enclosed dioritic enclaves in the CN unit, while the monzogranites of the SG unit were emplaced at 45.3 +/- 0. 7Ma. Geochemically, all rocks of the two units show sub-alkaline and metaluminbus signatures, with agpaitic index (AKI) values mostly less than 0. 9 and aluminum saturation index (A/NKC) values less than 1.0, thus can be grouped into metaluminous calcakaline I-type granites. They are also enriched in LREEs and LILEs (e.g., Rb, Pb), and depleted in HFSEs (e.g., Nb, Ta, Ti), showing the geochemical characteristics of arc magma rocks. Compared with granodiorites in the CN unit, the monzogranites in SG unit are rich in silicon and alkali, and have higher Rb/Sr and Rb/Ba ratios, and display more pronounced negative europium anomalies, indicating that the SG unit had experienced higher degrees of differentiation. The granodiorites and the enclosed dioritic enclaves in CN unit show accordantly depleted Hf isotopic compositions with epsilon(Hf)(t) values ranging from +4.6 to + 11. 5, and from +5. 0 to + 11. 1, respectively. The monzogranites in SG unit also show depeleted Hf isotopic compositions but with relatively wide variation range for epsilon(Hf)(t) values (= -0.5 similar to +14. 7). Based on a synthesis of petrography, geochronology, elemental and isotopic geochemistry and tectonics, we suggest that the granodiorites and the enclosed dioritic enclaves in CN unit were generated by mixing of depleted mantle derived magma and its induced juvenile crustal-melting magma. The monzogranites of the SG unit were emplaced after further differentiation of the mixed magma, and the ancient India crustal materials were most likely involved in their petrogenesis.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3597
EP 3612
UT WOS:000391345300003
ER  

PT J
AU Lu, TY
He, ZY
Zhang, ZM
Shui, XF
Yan, LL
AF Lu TianYu
He ZhenYu
Zhang ZeMing
Shui XinFang
Yan LiLi
TI Magma mixing of the Nyemo post-collisional granite from the Gangdese magmatic belt, Tibet: Evidence of microstructures
SO ACTA PETROLOGICA SINICA
AB The interaction between different melts during magma mixing process would have an influence on the nucleation and growth of the crystals, and could generate complex compositional variations within mineral or form disequilibrium textures between minerals. The Nyemo monzogranite is located in the middle of the Gangdese magmatic belt, and was typically formed in a post-collisional tectonic setting. In this study, the internal texture and chemical composition of plagioclase and amphibole from the Nyemo monzogranite have been analyzed in detail, and many disequilibrium textures have been revealed, including the resorption zone in plagioclase with harbor, round or sieve shapes, the spike composition zone in plagioclase and the occurrence of biotite mantled by amphibole. The An contents of the spike zone (37. 6 similar to 40. 6) and the resorption zone (48. 2 similar to 59. 5) are evidently higher than the An contents of other domains in the same plagioclase grain (18. 4 similar to 26. 4), indicating a change of magma composition during the crystallization of the plagioclase which may be resulted from a magma mixing event. Some biotite grains are mantled by euhedral amphibole and show harbor shaped rims. The resorption of biotite may be related to the rise of magmatic temperature during the magma mixing process, and the amphibole mantle was probably crystallized from the mixed magma. Therefore, the microstructures revealed from the Nyemo monzogranite provide new evidence for the magma mixing and evolution processes of the Gangdese magmatic belt.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3613
EP 3623
UT WOS:000391345300004
ER  

PT J
AU Dong, HW
Xu, ZQ
Li, Y
Liu, Z
AF Dong HanWen
Xu ZhiQin
Li Yuan
Liu Zhao
TI Genesis and geological significance of Early Jurassic gabbro in Medog area, the eastern part of the Gangdese magmatic belt
SO ACTA PETROLOGICA SINICA
AB This paper reports whole-rock major and trace element, LA-MC-ICP-MS zircon U-Pb ages, zircon Hf isotopic and Sr-Nd isotopic compositions from the gabbro occurring in Medog area, the eastern part of the Gangdese magmatic belt. LA-MC-ICP-MS zircon U-Pb isotopic dating indicates that the Medog gabbro emplaced at 185. 97 +/- 0. 33Ma. It contains SiO2 of 48. 19% similar to 54. 93%, MgO of 4. 53% similar to 12. 76% and Mg-# of 50. 0 similar to 67.4. It is characterized by its high content of CaO (7. 44% similar to 12. 11%), low content of alkali (Na2O =0. 93% similar to 2. 36% and K2O =0. 49% similar to 2. 21%). The REE distribution patterns are quite similar to that of the E-MORB. The trace elements such as Sr, V, Sc is enriched, while the HFSE such as Nb, Ta, Zr, Hf is depleted. The gabbro has higher epsilon(Nd)(t) values (-3. 06 similar to 2. 84) and lower initial Sr-87/Sr-86 ratios (0. 7059 similar to 0. 7103). The Medog gabbro is heterogenous in zircon epsilon(Hf)(t) values (- 4. 1 similar to 0), yielding relatively ancient zircon Hf crustal modal ages of 866 similar to 1036Ma. Combining with regional geology, geochronological, geochemical and isotopic data, we propose that the eastern part of the Gangdese magmatic belt was under the Neotethyan subduction setting during the Early Jurassic.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3624
EP 3634
UT WOS:000391345300005
ER  

PT J
AU Xiong, FH
Yang, JS
Gao, J
Lai, SM
Chen, YH
Zhang, L
AF Xiong FaHui
Yang JingSui
Gao Jiang
Lai ShenMing
Chen YanHong
Zhang Lan
TI Feature of Zedong podiform chromitite, eastern Yarlung-Zangbo suture zone in Tibet
SO ACTA PETROLOGICA SINICA
AB The Zedong ophiolite is in the eastern Yarlung-Zangbo suture zone (YZSZ) of Tibet, which consists chiefly of mantle peridotite, with lesser amounts of pyroxenite and gabbro. Seven small, lenticular bodies of chromitite ore have been found in the harzburgite, with ore textures ranging from massive to disseminate to sparsely disseminate. Individual ore bodies are 0.5 similar to 3m long, 0.2 similar to 1m wide and strick NW, parallel to the main structure of the peridotite, both of them are high-Cr chromitite (Cr-# = 67. 9 similar to 88. 5). The mineralogy and geochemistry of the Zedong peridotites suggest that they formed originally at a mid-ocean ridge (MOR) and were later modified by suprasubduction zone (SSZ) melts. Platinum group elements (PGE) of Zedong ophiolite have negative slope patterns with enrich Os, Rh, Pd, loss of Ir, Ru and Pt, indicating the process of modified by melt/fluid. Compare to Luobusa podiform chromitite and peridotite in mineral assemblages, mineral chemistry and geochemistry show that there are many similar character, even existence a good prospecting space.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3635
EP 3648
UT WOS:000391345300006
ER  

PT J
AU Zhang, L
Yang, JS
Liu, F
Lian, DY
Huang, J
Zhao, H
Yang, Y
AF Zhang Li
Yang JingSui
Liu Fei
Lian DongYang
Huang Jian
Zhao Hui
Yang Yan
TI The South Gongzhucuo peridotite massif: A typical MOR type peridotite in the western Yarlung Zangbo suture zone
SO ACTA PETROLOGICA SINICA
AB The South Gongzhucuo ophiolite is located to the south of Gongzhu Lake, Ali area, Tibet, belonging to the southern sub belt of the western Yarlung-Zangbo ophiolitic belt. The South Gongzhucuo ophiolite is mainly composed of mantle peridotites and gabbro dikes. About 80 percent peridotites are harzburgites and 20 percent are lherzolites, few of them are dunites. Mineral chemistry of the South Gongzhucuo peridotites are characterized by low Fo contents (89. 3 similar to 91. 4) of olivine; high Al2O3, contents (1. 89% similar to 6. 06%) in pyroxenes; and low Cr-# values (12. 7 similar to 28. 3) of Cr-spinet. Compared to the primitive mantle, the South Gongzhucuo peridotites have relatively higher MgO contents, and lower CaO, Al2O3, and TiO2 contents. The total rare-earth element (REE) contents of the South Gongzhucuo harzburgites and lherzolites are 0. 66 x 10(-6) similar to 1. 10 X 10(-6) and 0. 90 x 10(-6) similar to 3.78 x 10(-6), respectively, which are significantly lower than those of the primitive mantle. The chondrite-normalized REE patterns of the South Gongzhucuo mantle peridotite display slight enrichments in LREE. In the primitive mantle-normalized spider diagrams, the South Gongzhucuo peridotites exhibit intensively positive U anomalies, slightly positive Nd anomalies, and intensively negative Zr anomalies. The PGE contents of South Gongzhucuo harzburgites and lherzolites are 15. 26 x 10(-9) similar to 25. 23 x 10(-9) and 18. 74 x 10(-9) similar to 26. 86 x 10(-9), respectively. The chondrite-normalized PGE patterns of the South Gongzhucuo peridotites are consistent with that of the primitive mantle. Mineral and whole-rock geochemical characteristics of the South Gongzhucuo peridotites show an affinity to abyssal peridotites, indicating that it may have formed in the mid-ocean ridge setting. Through quantitative modeling, we conclude that the South Gongzhucuo peridoties formed after at most 16% degree of partial melting of the spinel-phase lherzolite mantle source. The LREE enrichments and relatively high Pd/Jr and Rh/Ir ratios suggest that they have experienced melt-rock reaction. Thus, we conclude that the South Gongzhucuo mantle peridotites have suffered low degrees of partial melting in the spinel-lherzolite stability field beneath a mid-ocean ridge environment, and were modified by melt-rock reaction in the same tectonic setting.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3649
EP 3672
UT WOS:000391345300007
ER  

PT J
AU Guo, GL
Yang, JS
Liu, XD
Xu, XZ
Wu, Y
AF Guo GuoLin
Yang JingSui
Liu XiaoDong
Xu XiangZhen
Wu Yong
TI In situ research on PGM in Luobusa ophiolitic chromitites, Tibet: Implications for the crystallization of the chromite
SO ACTA PETROLOGICA SINICA
AB This paper study on the in-situ distribution of PGM in three mining areas in the Luobusa deposit, various PGMs and its microstructure obtained so far from each mining area suggesting that PGM can record the evolutions of the host chromitites. In situ PGMs results from Luobusa mining area show that the parental melts in Luobusa chromitite have a condition with high temperature and low sulfur fugacity, suggesting the chromite forms during the process of melting rock reaction and/or crystallization differentiation. The PGM occurrence in Kangjinla mining area are mainly composite phase inclusions in chromitites, also a few single phase PGM host in the fracture, which implying the parental melts of Kangjinla chromite origin from the melt mingling process, and modified by hydrothermal fluid at the later stage. The PGM obtained from Xiangkashan chromitites sample mostly are awaruites, which occurred in the fracture or intercrystalline in chromitites. Maybe subjected to the process of serpentinisation and/or hydrothermal metamorphism after the chromite crystallization. Mineral associations and microstructure of platinum-group minerals (PGM) can provide an efficacious clue to understand the physical and chemical conditions during the crystallization of chromitite. Therefore, PGMs in situ study is significant for us to understand the formation of unusual mineral preserved in chromitite and the crystallization of chromitite, and the study on PGMs combining in-situ examination and mechanical separation can obtain both their abundance and textural information.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3673
EP 3684
UT WOS:000391345300008
ER  

PT J
AU Zhang, X
Li, XP
Wang, ZL
Zhao, LQ
Shi, TQ
Duan, WY
AF Zhang Xin
Li XuPing
Wang ZeLi
Zhao LingQuan
Shi TongQiang
Duan WenYong
TI Mineralogical and petrogeochemical characteristics of the garnet amphibolites in the Xigaze ophiolite, Tibet
SO ACTA PETROLOGICA SINICA
AB Within the Xigaze ophiolitic melang of the central Yalung Zangpo Suture Zone, we found garnet amphibolites of the metamorphic sole, and investigated the mineral chemistry, metamorphic P-T condition and geochemistry of garnet amphibolites. On the basis of mineral assemblages, four metamorphic stages of garnet amphibolites were distinguished as Am-1 + Pl(1) + Ep(1) + Ttn (M1); Grtc + Cpx-e + Ep(2) + Pl(2) + Rt (M2); Grt-r + Ep(3)/Czo(3) + Cpx-l + Am-3, + Pl(3), + Ttn (M3) and Prh + Ab + Czo + Chl + Cal (M4), respectively. In light of the P-T pseudosection in the SAFMCNHO system, combined with traditional geothermobarometer, the garnet amphibolites were proposed to have experienced pre-peak metamorphism with P-T conditions of 560 similar to 620 degrees C/9. 1 similar to 9. 8kbar; peak metamorphism 830 similar to 870 degrees C/18. 0 similar to 22. Okbar, retrograde stage 640 similar to 680 degrees C/10. 7 similar to 14. 9kbar, and finally ended within sub-green schist facies, figuring out an anticlockwise P-T path. Major elements show that rocks are low-K tholeiitic, with low TiO2 (0. 92% similar to 1. 29%), K2O (<0. 26%) and Na2O (0.24% similar to 2. 46%). The chondrite-normalized Rare Earth Elements (REEs) and primitive mantle-normalized multi-element patterns are similar to N-MORB, with depletion in light of REEs, but they show significant enrichment of large ion lithophile elements (LILEs, Rb, Ba, U) and partly depleted in high field stretch elements (HFSEs, Nb, Ti, Zr and Hf). Geochemical studies indicate that investigated rocks have affinities with N-MORB and arc-related components where is sourced from Supra Subduction Zone (SSZ) environment. The existence of the Bailang garnet amphibolite presents that the Xigaze ophiolite has been emplaced soon after it formed within an intra-oceanic subduction/emplacement.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3685
EP 3702
UT WOS:000391345300009
ER  

PT J
AU Yu, SY
Zhang, JX
Li, SZ
Sun, DT
Li, YS
Peng, YB
AF Yu ShengYao
Zhang JianXin
Li SanZhong
Sun DeYou
Li YunShuai
Peng YinBiao
TI "Barrovian-type" metamorphism and in situ anatexis during continental collision: A case study from the South Altun Mountains, western China
SO ACTA PETROLOGICA SINICA
AB Both metapelite and metabasite experienced medium-pressure granulite-facies metamorphism in the Tula area, South Altun. The metapelite is mainly composed of garnet + sillimanite + feldspar + biotite + quartz, and the mafic granulite consists of garnet + clinopyroxene + orthopyroxene + plagioclase + quartz. Anatexis of the metapelite is evidenced by petrological study in field and microscopy texture: (1) mineral assemblage of K-feldspar + quartz + plagioclase within garnet represents pseudomorphism of earlier melts; (2) microcline recognized along grain boundary of irregular biotite, indicating breakdown of biotite; (3) string of K-feldspar along boundary of quartz, plagioclase or K-feldspar; (4) irregular K-feldspar along garnet and sillimanite, suggesting that the garnet and sillimanite represent the residuum. Zircon U-Pb data indicate that both granulite-facies metamorphism and anatexis occurred simultaneously at similar to 450Ma. Therefore, medium-pressure granulite-facies metamorphism and anatexis occurred 40 similar to 50Myr later than the eclogite and HP granulite in the South Altun. However, it is controversial that the similar to 450Ma metamorphism, anatexis and magmatism define an independent tectonothermal event or overprinting of deep subducted continental slab.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3703
EP 3714
UT WOS:000391345300010
ER  

PT J
AU Zhang, C
Liu, XY
Yang, JS
Li, P
Zhang, LF
AF Zhang Cong
Liu XiaoYu
Yang JingSui
Li Peng
Zhang LiFei
TI The Neoproterozoic metamorphism of North Qaidam UHPM belt, western China : Constrain from petrological study and monazite dating of paragneiss
SO ACTA PETROLOGICA SINICA
AB The poly-phase orogeny information included in one orogenic belt is the key for studying the regional tectonic evolution at different time period. It also has important significance of understanding the rock association and geochemical evolution of different orogeny. However, the later orogenesis always fully or partially erases the information about the early orogenesis, making it much harder to investigate the metamorphism and geochronology information of the poly-phase orogenesis. Monazite, as a common accessary mineral in paragneiss, has high closure temperature of the U-Th-Pb isotopic system and essential to the fluid and metamorphic P-T conditions, making it much easier to record the abundant geochronological information about the poly-phase orogenesis. In-situ electron microprobe monazite dating method makes it possible to connect the geochronological information and the mineralogical characteristics and metamorphic reactions in order to get the P-T-t path of the mineral assemblage with different ages. We have combined in-situ electron microprobe monazite dating method with petrological investigations on the garnet-bearing kyanite/sillimanite biotite gneiss from the Xitieshan terrane of North Qaidam Caledonia ultrahigh pressure metamorphic belt and yielded 886 +/- 18Ma Grenville ages. The rare earth element distribution pattern is similar with the Neoproterozoic ones in the literature. By means of traditional mineral geothermobarametry, the high amphibolite facies 607 similar to 727 degrees C, 6.5 similar to 10. Okbar conditions has been conducted, which is slightly higher than the P-T condition recorded by the Paleozoic paragneiss. Compare with the trace element geochemistry with the Paleozoic paragneiss, the Grenville paragneiss are characterized by high total rare earth element and obvious Eu negative anomaly (Eu/Eu * = 0.50) with correspondingly be depleted in Ba and Sr element, which shows the active continental margin sediment characters. By reviewing the Grenville orogenesis and the formation and decomposition of the super-continent Rodinia globally, we consider that the North Qaidam UHP belt is related to the active continental margin region during the formation of super-continent Rodinia at Grenville age.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3715
EP 3728
UT WOS:000391345300011
ER  

PT J
AU Yuan, TY
Zhao, ZB
Zeng, QG
Liu, Y
AF Yuan TingYuan
Zhao ZhongBao
Zeng QingGao
Liu Yan
TI Petrological characteristics of the eclogite from Gemuri area, northwestern Tibet, and tectonic implications
SO ACTA PETROLOGICA SINICA
AB Occurring in the Longmu Co-Shuanghu suture zone, the Gemuri eclogite is an important component of the central Qiangtang high-pressure metamorphic belt, which was previously regarded as a consequence of cold subduction of the Palaeo-Tethyan Oceanic crust. Mineral assemblages of the Gemuri eclogite can be divided into four stages. The first stage consists of Fe3+ -bearing CaNa amphibole, paragonite, albite, chlorite, quartz, allanite enriched in LREE, Th and U, sphene and Mn-rich garnet core. The mineral assemblage of the second stage is composed of Mg-rich garnet, Fe-poor omphicite, trace-element-free clinozoisite, quartz, paragonite, rutile and pyrite. The third stage includes the Fe-rich garnet occurring in the rims of garnet porphyroblast, albite, chlorite, sphene and actinolite. The last stage is composed of magnetite, trace-element-free epidote and needlelike ilmenite. Semiquantitatively thermodynamic modeling has revealed that the core garnet was formed at T = 644 degrees C, P = 13. Okbar, lgfO(2) = -16.3 similar to -16.4, while the mantle garnet was formed at T = 695 degrees C, P = 16. 6kbar, lgfO(2), = -19.0 similar to -19. 5, indicating that the Gemuri eclogite is an intermediate-temperature eclogite rather than a cold eclogite as previously thought. In combination with previous studies, our work further suggests that tectonic evolution of the Palaeo-Tethyan Ocean is more complex than previously thought. Not only cold, but also intermediate-temperature oceanic subduction occurred. The Gemuri eclogite has suffered reduction in the prograde stage. The early Fe3+ -bearing Ca-Na amphiboles, allanites enriched in LREE, Th and U, as well as other water -bearing minerals formed at high oxygen fugacity are transformed into garnets, Fe-poor omphacites and trace-element-free clinozoisite, releasing water, REE, Th, U, and Ba in the subduction channel. However, none of the neogenic minerals in the exhumation stage contain these trace elements, suggesting that the trace elements were likely released from the subducted slabs, and then transferred to the overlying mantle wedge along with fluids. Our studies further illustrate that the processes responsible to the mass transferring from the down going slabs to the overlying mantle wedge are driven by the prograde metamorphism and reduction together. This highlights the origin of island-arc magmatic rocks with unique arc geochemical characteristics.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3729
EP 3742
UT WOS:000391345300012
ER  

PT J
AU Xu, XY
Cai, ZH
He, BZ
Yang, YX
Cheng, MW
He, C
AF Xu XiaoYin
Cai ZhiHui
He BiZhu
Yang YouXing
Cheng MuWei
He Cui
TI Thrust system and its evolution in eastern part of the basin-range junction belt between the West Kunlun and Tarim Basin
SO ACTA PETROLOGICA SINICA
AB The basin-range junction belt between Tibetan Plateau and Tarim Basin featured by deformation structure of thrust system, is an ideal object to study the relationship between Tibetan Plateau and Tarim Basin, is an important potential area to explore oil. Through field geological survey, satellite image interpretation and major seismic section interpretation, we analyzed the characteristics of thrust system in the basin-range junction belt of the West Kunlun-Tarim Basin, discussed its forming time combined with previous studies. We regard the thrust system of the northwestern Tarim basin-range junction belt composed of several thrust sheets which formed after Miocene and are younger increasingly from south to north. We illustrated its deformation extent and evolution process using balanced section technique. The upper crust shortening rate of the basin-range belt in Cenozoic is 36% similar to 38% and mainly occurred after Miocene. The thrust system is a result of remote effect of Cenozoic India-Asian collision event.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3743
EP 3752
UT WOS:000391345300013
ER  

PT J
AU Wang, N
Wu, CL
Ma, CQ
Lei, M
Guo, WF
Xin, Z
Chen, HJ
AF Wang Nan
Wu CaiLai
Ma ChangQian
Lei Min
Guo WenFeng
Zhang Xin
Chen HongJie
TI Geochemistry, zircon U-Pb geochronology and Hf isotopic characteristics for Granites in southern Dunhuang block
SO ACTA PETROLOGICA SINICA
AB Numerous Paleozoic granitoids emplaced in Dunhuang block. Aiming to better understand the tectonic evolution of Dunhuang block and the geodynamic significance, in this paper, Anpengou composite granites and Xiaocaohu granite in southern Dunhuang block were chosen to study by means of petrography, geochemistry, zircon U-Pb chronology and Hf isotopic analyses. The results show that: (1) the two granites had different rock assemblage types. Anpengou composite granites were mainly composed of Early Paleozoic syenogranite emplaced during the Silurian period (431Ma) and granite emplaced during the Devonian period (similar to 360Ma) and the Carboniferous period (similar to 340Ma), while Xiaocaohu porphyritic granite was emplaced during the Carboniferous period (similar to 340Ma). (2) Both Anpengou syenogranite and granite showed S-type granite features and similar Hf isotopic characteristics, with epsilon(Hf)(t) ranging from -11.7 to -6.3 and -12.3 to -5.5, and two-stage model age was varied in 1.8 similar to 2. 2Ga and 1.7 similar to 2.1Ga, respectively. Both source rocks of the Early Paleozoic syenogranite and the Late Paleozoic granite derived from meta-greywacke with part of metapelitic materials of Paleoproterozoic to Mesoproterozoic. Xiaocaohu porphyritic granite showed features of adakitic rocks and was generated by partial melting of thickened crust, with epsilon(Hf)(t) ranging from -16.7 to -4.9 and two -stage model age was varied in 1. 8 similar to 2.4Ga, indicating that the source rocks of Xiaocaohu porphyritic granite derived from the Paleoproterozoic crustal materials. In addition, some of the source rocks of the two granites may be related to the assemblage and break-up of Columbia supercontinent. (3) The residual rocks of Anpengou syneogranite, Anpengou granite and Xiaocaohu porphyritic granite were granulite, amphibolite and granulite-amphibole eclogite, which reflected the differences in the formation depth and grade of metamorphism. (4) The Early Paleozoic orogenic movement of Dunhuang block ended much later than the Central Orogenic Belt, but exhibited closely temporal-spatial coupling retionship with the Tianshan-Beishan orogenic belt in timing limitation and the distribution of the Paleozoic granites. Therefore, we proposed that the Dunhuang block was involved in the orogenic event of the Central Asian Orogenic Belt in both Early Paleozoic and Late Paleozoic.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3753
EP 3780
UT WOS:000391345300014
ER  

PT J
AU Ma, SW
Xu, ZQ
Zhang, ZK
Ma, Y
Zhao, ZB
Pang, X
Zhao, XW
Wang, H
AF Ma ShiWei
Xu ZhiQin
Zhang ZhongKun
Ma Yuan
Zhao ZhongBao
Pang Xue
Zhao XiaoWu
Wang Hui
TI Structural deformation and its constrains of mineralization of the Jiama copper-polymetallic deposit, southern Tibet
SO ACTA PETROLOGICA SINICA
AB Jiama copper polymetallic deposit locates in the middle-east part of the Gangdese metallogenic belt and is a typical large "collision" type deposit. The Jiama porphyry deposit is mainly skarn-type ore bodies associated hornfels-type and porphyry-type ore bodies. The mainly skarn-type ore bodies as a layered thick plate are distributed in the interlayer tectonic belt between Late Jurassic Duodigou Formation and Early Cretaceous Linbuzong Formation. Through detailed filed and core geological observation on the structural deformation features associated with the mineralization, since the Cenozoic, Jiama and its adjacent area have experienced two main regional deformation evens. The first deformation (D-1) associated with the subduction-collision of India-Eurasian plates developed a series of isoclinal folds and an interlayer tectonic belt between Late Jurassic Duodigou Formation and Early Cretaceous Linbuzong Formation, which probably provided important space for the development of Jiama deposit. The second deformation (D-2) formed a series of vertical or inclined slanting folds and reconstruction the D, folds. The contact part between Duodigou Formation and Linbuzong Formation existed thrust shearing action. The thrust fault and folds compose Jiama fold-thrust belt (Jiama decollement). The EBSD fabric result of quartz and calcite in mylonite showed that the Jiama decollement formed in the low temperature (about 400 degrees C). Four types of mineralization were founded spatially associated with the D-2 deformation. 1) The type 1 exists in the interlayer fracture of S-1, foliation and the metasandstone, which is folded with S-1, foliation together. 2) The type 2 is quartz sulfide veins that are parallel or cut across S-1, foliation were folded. 3) The type 3 is skarn-type ore bodies distributed in the interlayer tectonic belt. Banded skarn and copper mineralization had developed. 4) The type 4 is mainly quartz sulfide veins or carbonate sulfide veins with no deformation. We report new zircon U-Pb ages about 16.4Ma of the deformed granite veins. Combined with previous molybdenite Re -Os (14.5 similar to 15. 7Ma) and zircon U-Pb (14.1 and 14.2Ma) dating results, the second deformation (D-2) probably happened between 14 similar to 17Ma. Therefore, the second deformation (D-2) probably controlled the Jiama copper deposit. This study presents the structure and Mineralization process of Jiama copper polymetallic deposit and have important significance for further guide for regional prospecting.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3781
EP 3799
UT WOS:000391345300015
ER  

PT J
AU Cao, H
Vervoort, J
Wang, D
Li, GX
Neill, O
AF Cao Hui
Vervoort Jeff
Wang Da
Li GuangXu
Neill Owen
TI Triassic monazite ages and its geological significance of garnet-mica schist in Fenzishan Group, Jiaobei Massif
SO ACTA PETROLOGICA SINICA
AB The inclusion trail of garnet porphyroblasts in garnet-mica schists of Fenzishan Group, Jiaobei Massif record the multistage deformation and metamorphism history during rock formation. Garnets with clear zonation structures can be divided into core, mantle, and rim based on electron microprobe compositional mapping. The content variation of MgO, FeO, MnO, and CaO in garnet shows that the temperature of core to rim first increased then decreased, indicating prograde to retrograde metamorphism. The Y content in monazite decreases from the core to rim based on the compositional mapping of monazite grain. The 232.6 +/- 1.1Ma similar to 229.5 +/- 3.7Ma monazite U-Pb ages correspond to the prograde metamorphic growth process of garnet. Combined with 1869 +/- 72Ma zircon U-Pb age, it can be inferred that the garnet-mica schist in the Fengzishan Group has undergone at least two metamorphic events in the Paleoproterozoic and Triassic. The garnet-mica schist in the Fenzishan Group records the subduction-collision orogenic process of the Sulu UHP metamorphic belt in Triassic. The electron microprobe analysis of garnet shows an almandine composition, and indicates it had experienced mid-level regional metamorphism. It further indicates that although the garnet-mica schist in the Fenzishan Group was involved in the Triassic subduction-collision orogenic process of the Sulu UHP metamorphic belt, the subduction depth it reached was not very deep. This can be explained by the subduction erosion model for continental subduction process, and provides evidence for the hypothesis of deep subduction erosion model of continent-continent collision for the formation of the Sulu HP-UHP metamorphic terrain, which mentioned that part of Jiaobei Massif was partially dragged down during the 240 similar to 220Ma Yangtze plate subduction process. Further study is required to demonstrate if Jiaobei Massif experienced deep subduction UHP metamorphism.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3800
EP 3816
UT WOS:000391345300016
ER  

PT J
AU Chen, WW
He, BZ
Xu, ZQ
Cai, ZH
Rao, CL
Xiao, ZY
Yu, TX
Yu, ZY
AF Chen WeiWei
He BiZhu
Xu ZhiQin
Cai ZhiHui
Rao CunLi
Xiao ZhongYao
Yu TengXiao
Yu ZhuoYing
TI The thermal evolution history of Tangguzibas depression in the Meso-Cenozoic based on constraints of fission track method: Manifestation of the tectonic movements in Tibet Plateau
SO ACTA PETROLOGICA SINICA
AB The Mesozoic in the Tangguzibas depression was seriously absent, the reconstruction of tectonic evolution and uplifting process in this area is difficult during the Mesozoic. Low temperature thermal chronology technology of fission track is used in the thermal history of sedimentary basin in recent years, which is currently used in the geological thermal events dating, geological body thermal evolution history, tectonic uplift and denudation, and so on. It has its unique superiority; especially it can provide the processes of thermal history for lost many strata areas in superimposed basins. Based on fission track experiments, thermal evolution history simulation of drilling core samples in TangCl well, combined with stratigraphic development, this study reveals the thermal evolution of Tangguzibas depression in Meso-Cenozoic. Since Mesozoic, there are five cooling stages in the process of thermal evolution of Tangguzibas depression, including 248 similar to 240Ma (Early-Middle Triassic), 199 similar to 120Ma (Late Triassic to Early Cretaceous), 72 similar to 55Ma (Late Cretaceous to Paleocene), 24 similar to 15Ma (Late Oligocene to Early Miocene) and 7.4 similar to 2.2Ma (Late Miocene to Pliocene). In this five cooling stages, the average cooling rate can be divided into two stages and indicate the increasing in the early and the dropping in the later. The average cooling rate and uplifting rate increase gradually from the Triassic to the Miocene. The maximum average cooling rate attained 4.22 degrees C/Myr in the Early Miocene, and decreased gradually from the Late Miocene to present. The strongest and fastest uplifting occurred in the Tangguzibas depression, which responded with the Middle Himalayan Movement. The longest duration of the cooling and uplifting stages occurred in the Jurassic and early of Middle Cretaceous, the Tangguzibas depression was in the forebulge setting, almost unreceived the deposition of the Jurassic and the Middle and Upper Triassic were eroded during this time. The strata of the Middle and Upper Paleozoic in the Tangguzibas depression were experienced the higher paleo-geothermal before the Early and Middle Triassic, so that the apatites have been completely annealed and the zircons partially annealed, which were different with the Bachu Uplift. The polycycles of the cooling (uplifting) and warming (subsiding) events in the evolution of the Tangguzibas depression during the Meso-Cenozoic are coordinated with the closure of Paleo-Tethyan and Neo-Tethys and continent-continent collisions between the Indian to Asian Plates, as well as responses of the multi-stages tectonic movements of the Tibet Plateau in the Meso-Cenozoic.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3817
EP 3834
UT WOS:000391345300017
ER  

PT J
AU Zhang, RS
Cao, H
Zeng, M
Zhang, DX
Li, GX
AF Zhang RuiSi
Cao Hui
Zeng Min
Zhang DeXian
Li GuangXu
TI Scientific belt lithologic mapping based on ASTER spectral analysis: A case study from the Tashkorgan area (Xinjiang, China)
SO ACTA PETROLOGICA SINICA
AB Scientific belt mapping is based on the key geological question for the mapping area. However, some of the mapping areas are not easy to reach because of the high altitude, and lithologic mapping based on remote sensing image can provide useful information for the mapping project. Advanced Spaceborne Thermal Emission and Reflection (ASTER) remote-sensing data are useful in assisting lithologic mapping and, however, it has been rarely applied by in the Xinjiang and Tibetan areas and its effectiveness in these areas needs to be verified. In this paper, based on combined field geology and ASTER data analysis, we present mapping methodology and results from the Tashkorgan area of western Xinjiang. The Tashkorgan area is a key area for studying the Himalayan Tibetan orogen and the Tethyan ocean evolution. Nonetheless, the high altitude and poor transportation conditions of this area have imposed major difficulties on geological mapping. Lithologic types of the Tashkorgan area mainly include intermediate-high grade metamorphic rocks, Paleozoic (Ordovician, Silurian, Upper Carboniferous and Permian) meta-sedimentary rocks and various types of intrusive rocks. ASTER spectral analysis is shown to be effective identifying and discriminating the lithologic types. In particular, the ASTER TIR bands were processed first to reveal distribution of prominent lithologic types, including quartzose rock, quartz-deficient rock and carbonate and establish references for followed lithologic matching. The VNIR/SWIR band ratio indexes were demonstrated to effectively highlight spectral features related to lithologic composition of Fe3+, Fe-silicate, Al-OH, Mg-OH and carbonate. The lithologic mapping results provide more refined lithologic information than the previous map, which demonstrates the effectiveness of this method. The generalized procedures of ASTER-assisted lithologic mapping are applicable for future geologic mapping projects and studies in the similar areas such as Xinjiang and Tibet.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3835
EP 3846
UT WOS:000391345300018
ER  

PT J
AU Zhang, DX
Cao, H
Zeng, M
Xu, MZ
Li, GX
Xing, XH
AF Zhang DeXian
Cao Hui
Zeng Min
Xu MingZhu
Li GuangXu
Xing XianHong
TI Study on metallogenic genesis and metallogenic settings of Xinjiang "Pamir-type" iron deposit
SO ACTA PETROLOGICA SINICA
AB "Pamir-type" iron deposit is one of the most important categorized magnetite deposits in West Kunlun, Xinjiang, and its metallogenesis is still unclear. Previous studies on geological characteristics, ore-forming ages suggested that these magnetite deposits were obviously distinguished from those typical BIFs magnetite deposits globally. Wengjile magnetite deposit and Zileyi magnetite deposit, two representative magnetite deposits in this region, were selected in this study. Litho geochemistry of admellite and wall rocks, ore-forming minerals characteristics, trace element geochemistry and in situ Pb-Pb isotopic composition of magnetite were discussed in this study to explore the metallognesis and ore-forming background of "Pamir -type" iron deposit. Wengjile magnetite deposit lies in the contact zone between Wengjile biotite-admellite and Paleoproterozoic Bulunkuole Group biotite quartz-schist. The deposit is closely associated with Wengjile biotite-admellite in spatial and temporal. Geochemical characteristic of Wengjile biotite-adamellite is higher in SiO2 (69.10% similar to 74. 51%), Al2O5 (14.24% similar to 16.13%), K2O(4.46% similar to 4.91%) and Na2O (3.82% similar to 4.29%), and lower in MgO (0. 25% similar to 0. 69%), CaO (1.1% similar to 1. 99%) and TiO2 (0.139% similar to 0.398), and has a very narrow variation of Na2O/K2O (0.80 similar to 0. 87) and unanimous Rittmann Index (2.20 similar to 3. 24). Aluminum saturation index (1.44 similar to 1.51) suggested it belonged to a weak peraluminous rock. Total Rare Earth Element is higher (170.4 x 10(-6) similar to 400.5 x 10(-6), and delta Eu (0.44 similar to 0.87) is a strong negative Eu anomaly. The rocks contain variable contents of trace element in the trace element spider diagram, but generally have a similar variation trend such as systematic enrichment of LILE such as K, Rb, Sr, Ba (where Sr > 421 x 10(-6),Ba > 853 x 10(-6)) and REE but depletion of HFSE such as Nb, Ta, P and Ti. The content of the major oxides in Bulunkuole biotite quartz schist are SiO2 (57.07% similar to 60. 99%), and Al2O3 (14.46% similar to 8.61%, MgO (2.22% similar to 3. 60%), CaO (1.12% similar to 2. 86%),TiO2 (0.75% similar to 1. 12%), and are rich in REE (146.0 x 10(-6) similar to 200.5 x 10(-6), and has a median Eu anomaly (delta Eu is 0.65 similar to 0. 74). Trace element analyses suggested there is a lower Rb/Sr ratio (0.16 similar to 0. 89) and obvious depletion of Th, Zr, Hf, Nb, Ta, P and Ti but apparent positive anomaly of barium, which may suggest that the rock has the characteristics of aluminum-rich sedimentary formed in the environment of margin of ancient continental. The geochemical similarity between Wengjile biotite-admellite and Bulunkuole biotite schist demonstrated there is a genetic relationship between them. Zircon LA ICP-MS U-Pb dating of Wengjile biotite-admellite suggested the rocks formed around 15.0 +/- 0.3Ma and 15.4 +/- 0.2Ma. Trace element geochemistry of magnetite using LA ICP-MS indicated that magnetite from Wengjile magnetite deposit has higher Si, Mn, Zn, Pb, Hf, Sn and variable Mn and Ga, and magnetite from Zileyi magnetite deposit has relatively higher LILE such as Mg, Al, Ti, V, Co, Ni, Sc and lower variable Mn and Zn. In contrast, the range of variation of trace elements in magnetite from the Wengjile magnetite deposit is relatively larger, while the range of magnetite in the Zileyi magnetite deposit is relatively small.
The Pb-Pb isotopes of the magnetite from the two deposits are distinctly different. The Pb-206/Pb-204 of the magnetite from Wengjile magnetite deposit varied from 9. 0699 to 41. 4030 with an average value of 20. 4808, and Pb-207/Pb-204 varied between 11.0454 and 34. 1993 with an average of 17. 5573; and Pb-208/Pb-204 varied between 28. 6800 and 84. 1533 with an average value of 44. 8547. The Pb-206/Pb-204, Pb-207/Pb-204 and Pb-208/Pb-204 of the magnetite from Zileyi magnetite deposit are lower. The calculated isotope ratios of Pb-206/(204) Pb varied from 0.67 to 1.37 with an average of 1. 16; (208)pb/(206)ph varied from 1.85 to 3 61 with an average of 2. 24, and Pb-208/Pb-204 between 2.36 and 3.04, with an average of 2.56. Pb-Pb isotope results indicated that the magnetite from the Wengjile magnetite deposit may be related to biotite-adamellite and is hydrothermal but magnetite from Zileyi was not. In summary, there are not only deposits -related to sediment process, but also some hydrothermal magnetite deposits, which related to magmatic hydrothermal activity in the Tashkurgan region.
SN 1000-0569
EI 2095-8927
PD DEC
PY 2016
VL 32
IS 12
BP 3847
EP 3864
UT WOS:000391345300019
ER  

EF  

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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
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