Tong Y.-B.,Chinese Academy of Geological Sciences |
Tong Y.-B.,Key Laboratory of Paleomagnetism and Tectonic Reconstruction |
Yang Z.,Capital Normal University |
Wang H.,Chinese Academy of Geological Sciences |
And 4 more authors.
Tectonophysics | Year: 2015
Paleomagnetic studies were conducted on the Eocene and Oligocene strata at the western part of the Chuan Dian Fragment in order to describe the crustal deformation induced by continuous penetration of the Indian plate into Eurasia during the late Cenozoic. High-temperature magnetic components with unblocking temperatures of ~680°C were isolated, and positive fold and/or reversal tests reveal the primary nature of the magnetization. The tilt-corrected site-mean directions obtained from the Oligocene and middle-early Eocene strata are, respectively, Ds =200.9°, Is =-31.3°, k =52.8, α 95 =7.7° and Ds =29.7°, Is =32.0°, k =44.9, α 95 =5.6°. Comparison of these results with previous paleomagnetic data from the Chuan Dian Fragment shows that the western and central parts of the Chuan Dian Fragment experienced ~20° integral clockwise rotation relative to East Asia since the middle Miocene. However, the eastern part of the Chuan Dian Fragment has experienced different rotational deformation relative to East Asia since the Pliocene, because of the intense regional crustal deformation and activity on fault systems. The eastern boundary of the Chuan Dian Fragment was bounded by the Yuanmou-Luezhijiang left lateral strike-slip fault prior to the Pliocene, and then substituted by the Xiaojiang left lateral strike-slip fault since the Pliocene, due to the eastwards spreading of the clockwise rotational movement of the Chuan Dian Fragment. The evolutionary characteristics of the Ailaoshan-Red River and Xianshuihe-Xiaojiang strike-slip faults were controlled by the difference between the clockwise rotational extrusion velocities of the Chuan Dian Fragment and the Indochina Block. © 2015 Elsevier B.V.
Hu J.,East China Mineral Exploration and Development Bureau for Non Ferrous Metals |
Hu J.,Nanjing University |
Jiang S.-Y.,Nanjing University |
Zhao H.-X.,Hohai University |
And 8 more authors.
Journal of Asian Earth Sciences | Year: 2012
The Huashan complex granitic batholith, occurred in the core of the Xiaoqinling orogen and gold mineralization belt along the south margin of the North China Craton, consists of amphibole monzogranite and biotite monzogranite in the Wengyu and Fangshanyu valleys, respectively. Zircon LA-ICP-MS U-Pb dating yields ages of 205±2Ma and 132±1Ma for the Wengyu and Fangshanyu granites, respectively, which represent the two major episodes of Mesozoic magmatism in the region. These rocks are characterized by metaluminous, high silica and total alkalinity, and have high FeO total/(FeO total+MgO) ratios, high large-ion lithophile elements (LILEs, especially Sr and Ba) and light rare earth elements (LREEs), and low heavy rare earth elements (HREEs) and Y concentrations and insignificant negative Eu anomalies. The Wengyu granites have higher Ba and Sr contents, which can be classified as high Ba-Sr granites, whereas the Fangshanyu granites show much lower Ba and Sr contents and display an adakitic affinity. Elemental and isotopic compositions suggest that the main sources of both the Wengyu and Fangshanyu granites are likely the ancient basement materials of Taihua Group. However, the high Ba and Sr contents of the Wengyu granites require addition of small amounts of enriched lithospheric mantle metasomatised by fluid/melt derived from pelagic sediments-bearing subducted slab in the sources. The Wengyu granites were most likely generated earlier by partial melting of the lowest part of the crust due to the subducted slab break-off under the post-collision extensional stage of the continental collision orogeny. The Fangshanyu granites might be mainly derived later from the partial melting of thickened lower crustal materials, representing by the Taihua Group basement rocks, corresponding to the tectono-magmatism of the post-orogeny to rift extensional environment during the tectonic transition from the Paleo-Tethys subduction-collision system to the Paleo-Pacific regime. © 2012 Elsevier Ltd.
Hou D.-Z.,Central South University |
Wu X.-B.,Central South University |
Li Z.,Central South University |
Liu Y.-H.,East China Mineral Exploration and Development Bureau for Non Ferrous Metals
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2015
Based on the research of geological characteristics of the Dahebian deposit, the compositions of S, O, Sr isotopes, rare earth elements and organic geochemistry were systematically studied to discuss the material sources of the Dahebian barite deposit. The positive correlation between δ18OSMOW and δ34SV-CDT in the ores proves that S and O elements were involved as SO42-. High δ34SV-CDT was caused by sulfur isotope fractional distillation in the hydrothermal fliud and sulfate reducing bacteria fractional in seawater, which suggests that sulfur may be derived from hydrothermal fluid and seawater. Meanwhile, the ore and wall rock have almost the same high ratio of light rare earth elements(LREE) to heavy rare earth elements(HREE), Eu and Ce anomalous, which indicates that they are the product of hydrothermal sedimentation. Additionally, biomarkers show that the organic matter is mainly sourced from the lower organisms, such as marine bacteria and algae. According to comprehensive research on metallogenic setting and Sr isotope, the material of barium mainly comes from submarine hydrothermal sediments. Comprehensively, it is believed that the ore-forming material may mainly comes from the seawater and hydrothermal sedimentation, both crustal and mantle components play important roles in providing material. Besides, lower marine organisms are involved. ©, 2015, Central South University of Technology. All right reserved.
Wu C.-Z.,Nanjing University |
Wu C.-Z.,Wuhan University |
Liu S.-H.,Nanjing University |
Gu L.-X.,Nanjing University |
And 2 more authors.
Journal of Asian Earth Sciences | Year: 2011
The Baishitouquan (BST) pluton is a topaz- and amazonite-bearing leucogranite intrusion located in the Middle Tianshan orogen of Xinjiang, northwestern China. This pluton exhibits five lithological zones gradational from the bottom upwards: leucogranite (zone-a), amazonite-bearing granite (zone-b), amazonite granite (zone-c), topaz-bearing amazonite granite (zone-d) and topaz albite granite (zone-e). Contents of REE and other trace elements were analysed on major and accessory minerals, including quartz, plagioclase, K-feldspar, white micas, topaz, fluorite, garnet, zircon and monazite, separated from above five zones of the BST pluton. Chondrite-normalized REE patterns of minerals from zone-a to zone-e display clear convex tetrad effect, and the TE1,3 (quantification factor of tetrad effect) values of these minerals increases from zone-a to zone-e, except that a quartz sample from zone-b and zircon from zone-c exhibits W-type tetrad effect. Therefore, we conclude that REE tetrad features of the minerals, such as quartz, plagioclase, zircon, garnet and monazite, are inherited directly from the melt and have not significantly affected by both fractional crystallization and surface weathering. With progressing of magmatic differentiation, total REE contents decrease, Eu anomaly becomes more negative, whereas Nb/Ta, Zr/Hf and Y/Ho ratios decrease gradually from zone-a to zone-e with increasing TE1,3 values. Therefore, we suggest that F-rich magmatic fluid-melt interaction above its solidus may leave the residual silicate melt with the features of very low contents of all REE, subchondritic Y/Ho, Zr/Hf and Nb/Ta values, and with an M-type tetrad pattern, including minerals crystallizing from it. Such a pattern is manifested by both whole-rock and separate minerals. Hydrothermal fluid-rock interaction played only a minor role to the convex tetrad effect of the minerals and their host rocks. © 2010 Elsevier Ltd.
Shao Y.,Central South University |
Shao Y.,Nanjing University |
Zhang Z.-Z.,East China Mineral Exploration and Development Bureau for Non Ferrous Metals |
Zhang Z.-Z.,Nanjing University |
And 8 more authors.
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2012
The Baishitouquan amazonite granite pluton near Xinxinxia of Hami County, Xinjiang, China, includes five lithological zones. They are, up the pluton, the leucogranite zone, amazonite-bearing granite zone, amazonite granite zone, topaz-bearing amazonite granite zone and topaz albite granite zone. Irregular-shaped cavities formed during the late magmatic stage are found in all the five zones. These cavities, mostly less than 2 mm in size, were filled dominantly with fluorite accompanied by garnet, cassiterite, albite and white mica. These infilling minerals were crystallized late at the magmatic-hydrothermal transition stage. The composition of the infillings indicates that the product at this stage is an evolving calcium-, magnesium-, and iron-poor and fluorine-rich peraluminous granite, which is characterized by abundant fluorite, and that the fluorides or fluorine complexes are the important forms that transport tin in fluids at this stage. In case the cavities are connected by tectonic fractures, the tin initially enriched in the infilling fluids will migrate and then precipitate the metallic minerals at favorable sites with formation of a vein-type tin deposit.
Lei R.-X.,Nanjing University |
Wu C.-Z.,Nanjing University |
Wu C.-Z.,Wuhan University |
Gu L.-X.,Nanjing University |
And 3 more authors.
Gondwana Research | Year: 2011
The Central Tianshan zone is located between the Turpan-Hami and Tarim blocks and played a pivotal role in crustal evolution and collisional tectonics of the southern Altaids (or the Central Asian orogenic belt). The Xingxingxia granodiorite in the eastern Central Tianshan is an Early Paleozoic (424.9±5.8Ma) intrusion. Petrography, geochemistry and Sr-Nd-Hf isotopes suggest that the Xingxingxia granodiorite was genetically related to a volcanic arc, emplaced above a subduction zone. Thus, the Central Tianshan zone was a magmatic arc above an early Paleozoic subduction zone of the Paleoasian ocean. We present LA-ICP-MS zircon U-Pb dating and Hf isotope determinations of Precambrian zircon grains trapped in the Xingxingxia granodiorite. Three populations of inherited zircons indicate that Neoproterozoic (809±41Ma; εHf(t)=0.10-5.73), Mesoproterozoic (~1400Ma; εHf(t) 8.71-10.05) and Paleoproterozoic (~1750Ma; εHf(t) 0.11 and 4.80) tectonomagmatic events in the Central Tianshan zone, which are comparable with those in the Tarim block. Combined with a series of similar geological characteristics between these two blocks, it is suggested that the Central Tianshan zone might have been originally a part of the Tarim block, and was separated from it during the Early Paleozoic time due to pull-apart caused by southward subduction of the Northern Tianshan ocean, a branch of the Paleoasian ocean. © 2011 International Association for Gondwana Research.