Wang Y.,China University of Geosciences |
Xue C.,China University of Geosciences |
Wang J.,China University of Geosciences |
Peng R.,China University of Geosciences |
And 4 more authors.
International Geology Review | Year: 2015
The petrogenesis and geodynamic setting of magmatic rocks in Eastern Tianshan, Xinjiang, are attracting increasing attention. This study explores these issues by providing SHRIMP zircon U-Pb dating, and element geochemical and Hf isotope data of magmatic rocks exposed in the Yandong region of Eastern Tianshan, Xinjiang. SHRIMP zircon U-Pb dating data indicate that the magmatic activities occurred around 335 Ma, and that mineralization of the Yandong porphyry Cu deposit occurred during the same period as that of the rock formation in the region or slightly later. All the magmatic rocks in Yandong are sub-alkaline or high-K, calc-alkaline with A/CNK values ranging from 0.91 to 2.70, enriched in K, Rb, and Ba and clearly depleted in Nb, Ta, P, Ti, and Th, and have geochemical characteristics typical of adakites (i.e, high Al2O3, high La/Yb ratios and Sr contents, low Y and HREE contents, and positive Eu anomalies). In situ Hf isotopic analyses of zircons that had previously been dated by SHRIMP yielded positive initial εHf(t) values ranging from +9.4 to +15.8. We suggest that the Palaeo-Tianshan oceanic crust subducted northward beneath the Dananhu-Tousuquan arc belt during the early Carboniferous, and the Yandong magmatic rocks were induced by partial melting of the subducted Palaeo-Tianshan oceanic slab, subsequently having been hybridized by peridotite in the mantle wedge. The slab melts play a crucial role particularly in the relatively closed magma system responsible for generating the Yandong porphyry Cu deposit. © 2014 © 2014 Taylor & Francis.
Wang Y.-H.,China University of Geosciences |
Xue C.-J.,China University of Geosciences |
Gao J.-B.,Xinjiang Bureau of Geology and Mineral Exploration |
Zhang F.-F.,China University of Geosciences |
And 3 more authors.
Ore Geology Reviews | Year: 2016
The Hongshi gold deposit is located in the southwestern margin of the Kanggur-Huangshan ductile shear zone in Eastern Tianshan, Northwest China. The gold ore bodies are predominantly hosted in the volcanogenic metasedimentary rocks of the Lower Carboniferous Gandun Formation and the Carboniferous syenogranite and alkali-feldspar granite. The syenogranite and the alkali-feldspar granite yield SHRIMP zircon U-Pb ages of 337.6±4.5Ma (2σ, MSWD=1.3) and 334.0±3.7Ma (2σ, MSWD=1.1), respectively, indicating that the Hongshi gold deposit is younger than 334Ma. The granitoids belong to shoshonitic series and are relatively enriched in large ion lithophile elements (Rb, K, Ba, and Pb) and depleted in high field-strength elements (Nb, Ta, P, and Ti). Moreover, these granitoids have high SiO2, Al2O3, and K2O contents, low Na2O, MgO, and TiO2 contents, low Nb/Ta ratios, and slightly positive Eu anomalies. The εHf(t) values of the zircons from a syenogranite sample vary from +1.5 to +8.8 with an average of +5.6; the εHf(t) values of the zircons from an alkali-feldspar granite sample vary from +5.0 and +10.1 with an average of +7.9. The δ34S values of 10 sulfide samples ranged from -11.5‰ to +4.2‰, with peaks in the range of +1‰ to +4‰. The above-mentioned data suggest that the Hongshi granitoids were derived from the melting of juvenile lower crust mixed with mantle components formed by the southward subduction of the paleo-Tianshan ocean plate beneath the Aqishan-Yamansu island arc during the Early Carboniferous. The Hongshi gold deposit was formed by post-collisional tectonism during the Permian. The granitoids most likely acted as impermeable barriers that prevented the leakage and runoff of ore-bearing fluids. Thus, the granitoids probably played an important role in controlling gold mineralization. © 2015 Elsevier B.V.
Wang Y.H.,China University of Geosciences |
Xue C.J.,China University of Geosciences |
Liu J.J.,China University of Geosciences |
Wang J.P.,China University of Geosciences |
And 4 more authors.
Yanshi Xuebao/Acta Petrologica Sinica | Year: 2014
The petrogenesis and geodynamic setting of magmatic rocks in eastern Tianshan are attracting increasing attention. This study explores these issues by providing SIMS zircon U-Pb dating, whole-rock geochemical, and Lu-Hf isotope data of the Tuwu porphyry copper deposit of eastern Tianshan, Xinjiang. The Tuwu porphyry copper deposit is located in the middle of the Late Paleozoic Dananhu-Tousuquan arc belt in the eastern Tianshan tectonic belt. The Carboniferous Qieshan Group is the main ore-hosting stratum. The andesite and dioritic porphyrite are the ore-hosting rocks, while the tonalitic rocks are the ore-bearing rocks. SIMS zircon U-Pb dating data indicate that the ore-bearing rocks occurred around 335Ma, and that mineralization of the Tuwu porphyry copper deposit occurred during the same period as that of the rock formation in the region or slightly later. The andesite and dioritic porphyrite are island arc volcanic rocks and formed by the same magmatism. However, the mineralized tonalitic rocks have adakitic characteristics. In situ Hf isotopic analyses of zircons yielded positive initial εHf(t) values ranging from +6.3 to +16.1, indicating the ore-bearing rocks were most likely derived from partial melting of a subducted oceanic slab. Therefore, we suppose that the North Tianshan oceanic crust subducted northward beneath the Dananhu-Tousuquan arc belt during the Early Carboniferous, and the Tuwu adakitic magmas were derived from partial melting of the subducted oceanic slab, hybridized subsequently by peridotite in the mantle wedge. During the adakitic magmas ascent, large amounts of metallogenetic elements were released, and accumulated further on the top of the rock bodies.
Zhang D.,Hefei University of Technology |
Zhou T.,Hefei University of Technology |
Zhou T.,Wuhan University |
Yuan F.,Hefei University of Technology |
And 4 more authors.
Acta Petrologica Sinica | Year: 2010
There are a lot of Permian basalts lay in the Kupukuziman Formation and Kaipaizileike Formation in the Tarim basin. LA-ICPMS U-Pb precise age and in-situ Hf isotope and trace and rare earth element compositions of zircons from the basalts in the Kupukuziman Formation have been analysed in this work. The weighted average age of zircons from the bottom basalt in the group is 291.9 ± 2.2 Ma (MSWD= 0.30, n= 17) , it is considered to be the primal time of the mafic magmatic,activity in Permian. The zircon age of 293.9 ± 4.6 Ma from the top basalt in the Kupukuziman Formation is consistent with the age of the bottom basalts within error, which suggests the basaltic magmatic activity is short-lived. Therefore the petrogenic age of the basalts in the Kupukuziman Formation is around 291.9 ± 2.2 Ma. Many inherited or captured zircons hosted in the basalt refer that the basaltic magma experienced crustal contamination during the rising emplacement. The in-situ trace elements and REE show that the zircons from the basalts in the Kupukuziman Formation have typical characters of mafic magmatic origin without any latter interruption such as alteration. The εHf (t) of zircons in the Kupukuziman Formation is - 4.84 ∼ - 0.65, indicate that the basalts were derived from the enriched lithosphere mantle. Based on these results we propose that the Permian mafic magma of basalts in the Tarim Basin were derived from the enrichedtype lithosphere mantle which was different from the source mantle of the coeval A-type granite in the Junggar area, northern Xinjiang.