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| 1 | Late Triassic sedimentary records in the northern Tethyan Himalaya:Tectonic link with Greater India显示文摘The Upper Triassic flysch sediments(Nieru Formation and Langjiexue Group)exposed in the Eastern Tethyan Himalayan Sequence are crucial for unraveling the controversial paleogeography and paleotectonics of the Himalayan orogen.This work reports new detrital zircon U-Pb ages and whole-rock geochemical data for clastic rocks from flysch strata in the Shannan area.The mineral modal composition data suggest that these units were mainly sourced from recycled orogen provenances.The chemical compositions of the sandstones in the strata are similar to the chemical composition of upper continental crust.These rocks have relatively low Chemical Index of Alteration values(with an average of 62)and Index of Compositional Variability values(0.69),indicating that they experienced weak weathering and were mainly derived from a mature source.The geochemical compositions of the Upper Triassic strata are similar to those of graywackes from continental island arcs and are indicative of an acidicintermediate igneous source.Furthermore,hornblende and feldspar experienced decomposition in the provenance,and the sediment became enriched in zircon and monazite during sediment transport.The detrital zircons in the strata feature two main age peaks at 225-275 Ma and 500-600 Ma,nearly continuous Paleoproterozoic to Neoproterozoic ages,and a broad inconspicuous cluster in the Tonian-Stenian(800-1200 Ma).The detrital zircons from the Upper Triassic sandstones in the study area lack peaks at 300-325 Ma(characteristic of the Lhasa block)and 1150-1200 Ma(characteristic of the Lhasa and West Australia blocks).Therefore,neither the Lhasa block nor the West Australia blocks likely acted as the main provenance of the Upper Triassic strata.Newly discovered Permian-Triassic basalt and mafic dikes in the Himalayas could have provided the 225-275 Ma detrital zircons.Therefore,Indian and Himalayan units were the main provenances of the flysch strata.The Tethyan Himalaya was part of the northern passive margin and was not an exotic terrane separated from India during the Permian to Early Cretaceous.This evidence suggests that the Neo-Tethyan ocean opened prior to the Late Triassic and that the Upper Triassic deposits were derived from continental crustal fragments adjacent to the northern passive continental margin of Greater India. | Huawen Cao Yong Huang Guangming Li Linkui Zhang Jianyang Wu Lei Dong Zuowen Dai Liu Lu | 2018 | Geoscience Frontiers2018，9，1： | 27 |
| 2 | Petrogenesis of Late Cretaceous Jiangla'angzong I-Type Granite in Central Lhasa Terrane, Tibet, China: Constraints from Whole-Rock Geochemistry, Zircon U-Pb Geochronology, and Sr-Nd-Pb-Hf Isotopes显示文摘The Jiangla'angzong granite in the northern part of the Central Lhasa Terrane is composed of syenogranite and adamellite. LA-ICP-MS zircon U-Pb analyses suggest that syenogranite has a weighted mean ^(206) Pb/^(238) U age of 86±1 Ma(mean square weighted deviation=0.37), which is in accordance with the muscovite Ar-Ar age(85±1 Ma) of Cu-Au ore-bearing skarns and the zircon U-Pb age(84±1 Ma) of adamellite. This suggests that the Jiangla'angzong magmatism and Cu–Au mineralization events took place during the Late Cretaceous. The granite contains hornblende, biotite, and pyroxene, and does not contain Al-bearing minerals, such as muscovite, cordierite, and garnet. It has high contents of SiO_2(65.10–70.91 wt%), K_2O(3.44–5.17 wt%), and total K_2O+Na_2O(7.13–8.15 wt%), and moderate contents of A_(12)O_3(14.14–16.45 wt%) and CaO(2.33–4.11 wt%), with a Reitman index(σ43) of 2.18 to 2.33, and A/CNK values of 0.88 to 1.02. The P_2O_5 contents show a negative correlation with SiO_2, whereas Pb contents show a positive correlation with SiO_2. Th and Y contents are relatively low and show a negative correlation with the Rb contents. These characteristics suggest that the Jiangla'angzong granite is a high K calc–alkaline metaluminous I–type granite. It is enriched in light rare earth elements(LREE) and large ion lithofile elements(LILE), and depleted in heavy rare earth elements(HREE) and high field strength elements(HFSE), with LREE/HREE ratios of 11.7 to 18.1. The granite has negative Eu anomalies of 0.58 to 0.94 without obvious Ce anomalies(δCe=1.00–1.04). The relatively low initial 87 Sr/86 Sr ratios of 0.7106 to 0.7179, positive εHf(t) values of 1.0 to 4.1, and two-stage Hf model ages(TDM2) ranging from 889 Ma to 1082 Ma, These geochemical features indicate that the granite derived from a juvenile crust. The(^(143) Nd/^(144) Nd)_t values from the Jiangla'angzong granite range from 0.5121 to 0.5123, its εNd(t) values range from-10.17 to-6.10, its(^(206) Pb/^(204) Pb)_t values range from 18.683 to 18.746, its(^(207) Pb/^(204) Pb)_t values range from 15.695 to 15.700, and its(^(208) Pb/^(204) Pb)_t values range from 39.012 to 39.071. These data indicate that the granite was formed by melting of the upper crust with the addition of some mantle materials. We propose that the Jiangla'angzong granite was formed during the postcollision extension of the Qiangtang and Lhasa terranes. | LIU Hong LI Guangming HUANG Hanxiao CAO Huawen YUAN Qian LI Yingxu OUYANG Yuan LAN Shuangshuang LU Menghong YAN Guoqiang | 2018 | Acta Geologica Sinica(English Edition)2018，92，4： | 20 |
| 3 | Timing of formation of the Hongdonggou Pb-Zn polymetallic ore deposit,Henan Province,China:Evidence from Rb-Sr isotopic dating of sphalerites显示文摘The Hongdonggou Pb-Zn polymetallic ore deposit,located in the southwestern part of the Luanchuan Mo-W-Pb-Zn-Ag polymetallic ore mineralization in Henan Province,China,is an important part of the East Qinling metallogenic belt.The orebodies in the deposit,which are vein,bedded and lenticular,are mainly hosted in the syenite porphyry,and formed within the carbonate and clastic rocks of the Yuku and Qiumugou formations partially.The genesis of the deposit has previously been argued to be of hydrothermal-vein type or of skarn-hydrothermal type.In this study,we report the results of Rb-Sr isotopic dating based on sphalerites from the main orebody of the Hongdonggou Pb-Zn polymetallic ore deposit,which yield an isochron age of 135.7 ± 3.2 Ma,constraining the timing of mineralization as early Cretaceous.The age is close to those reported for the Pb-Zn deposits in the Luanchuan ore belt.The(^(87)Sr/^(86)Sr),values of the sphalerites(0.71127 + 0.00010) are lower than that of terrigenous silicates(0.720) and higher than the mantle(0.707),suggesting that the metallogenic components were mainly derived through crust-mantle mixing.Combining the results from this study with those from previous work,we propose that the Hongdonggou Pb-Zn polymetallic ore deposit is a hydrothermal-vein deposit associated with the early Cretaceous tectonothermal event,and the mineralization is controlled by NWand near EW-trending faults in the Luanchuan Mo-W-Pb-Zn-Ag polymetallic ore concentration belt. | Fan Yang Gongwen Wang Huawen Cao Ruixi Li Li Tang Yufeng Huang Hao Zhang Fei Xue Wenjuan Jia Nana Guo | 2017 | Geoscience Frontiers2017，8，3： | 2 |
| 4 | Hydrothermal Zircon Geochronology in the Shangxu Gold Deposit and its Implication for the Early Cretaceous Orogenic Gold Mineralization in the Middle Bangonghu–Nujiang Suture Zone显示文摘As a typical orogenic gold deposit in Tibet,Shangxu gold deposit is located at the Bangong Lake–Nujiang River Metallogenic Belt in the south of Qinghai–Tibet Plateau.In this paper,zircon U-Pb dating,trace elements and Hf isotopic analysis were performed on Au-bearing quartz veins in the Shangxu gold deposit.Zircons from Au-bearing quartz veins can be divided into three types:detrital,magmatic,and hydrothermal zircons.There are two age peaks in detrital zircons:ca.1700 Ma and ca.2400 Ma.There are two groups of concordant ages including 157±4 Ma(MSWD=0.69)and 120±1 Ma(MSWD=0.19)in magmatic zircons,in whichεH f(t)value of ca.120 Ma from the magmatic zircons range from+8.24 to+12.9.An age of 119±2 Ma(MSWD=0.42)was yielded from hydrothermal zircons,and theirεH f(t)values vary between+15.7 and+16.4.According to sericite Ar-Ar age,this paper suggests that an age of 119±2 Ma from hydrothermal zircons represent the formation age of the Shangxu gold Deposit,and its mineralization should be related to the collision between Lhasa Block and Qiangtang Block.The metallogenic age is basically the same as the diagenetic age of Mugagangri granite,andεH f(t)value of hydrothermal zircon is significantly higher than that of the contemporaneous magmatic zircon,which indicates that there is a genetic relationship between the gold mineralization and the deep crust-mantle magmatism. | HUANG Hanxiao LUOSANG Jiancuo DAI Zuowen LIU Hong FU Jiangang LI Guangming CAO Huawen ZHOU Qing | 2021 | Acta Geologica Sinica(English Edition)2021，95，4： | 1 |
| 5 | The Early-Middle Triassic Supervolcano in the Yangtze Block,South China and associated obstacles to biotic recovery显示文摘The end-Permian mass extinction was one of the major global crises spanning the entire Early Triassic or longer.Eruptions of volcanos were one of the factors that delayed the biotic recovery after this event.Supervolcano eruptions can cause catastrophic effects on global environment,climate,and life.Here we investigate the tuff layers from Early-Middle Triassic boundary in the Yangtze Block and identify a supervolcano eruption event.The zircon U-Pb ages of the section-Langdai,section-Daijiagou and section-Longmendong tuff samples are 247.1±1.9 Ma,247.6±2.0 Ma and 247.7±1.7 Ma,respectively.These ages mark the Olenekian-Anisian boundary.The zircon grains from the tuff layers have negativeεHf(t)(-15.3 to-0.8),two-stage Hf model(TDM2)ages(1.7 to 2.2 Ga)and display high-δ18O values(mostly>10‰).Clay minerals and quartz dominate the rock composition.The whole rock compositions show that the tuff layers were derived from magma of intermediate to felsic composition,which formed by the remelting of Paleoproterozoic materials of continental crust.The volcanic eruption site is located in the Jinshajiang-Ailaoshan-Song Ma suture zone in the southwestern margin of the Yangtze Block.A combination of the closure of the Paleo-Tethys Ocean Basin and the collision of the Indochina Block and South China contributed to the eruption,which was a supervolcano eruption under the active continental margin arc settings.We speculate that this supervolcano eruption might have contributed to the delayed biotic recovery after the end-Permian mass extinction. | Haifeng Chen Hao Zou MSantosh Huawen Cao Franco Pirajno Changcheng Huang Mingcai Hou | 2024 | Geoscience Frontiers2024，15，1： | 0 |
| 6 | Zircon U-Pb Age of the Shangxu Gold Deposit from Bangong-Nujiang Co, Northern Tibet, and Restriction on the Early Cretaceous Orogenic Gold Mineralisation显示文摘Objective The Tibetan Plateau is the largest continent-to-continent collision belt in the world.Two orogenic gold mineralisation belts have been recognized in this collision belt,which are as follows:the Indus-Yarlung Zangbo suture zone orogenic gold belt(IYOG),represented by the Mayoumu and Bangbu gold deposits,and the | HUANG Hanxiao LI Guangming LIU Hong CAO Huawen ZHANG Zhilin | 2018 | Acta Geologica Sinica(English Edition)2018，92，4： | 0 |
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