Geochemical Characteristics and Petrogenesis of Permian Basaltic Rocks in Keping Area,Western Tarim Basin:A Record of Plume-Lithosphere Interaction  

作　　者：于峻川 莫宣学 喻学惠 董国臣 付强 邢凤存 

机构地区：[1]State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences [2]School of Earth Sciences and Mineral Resources,China University of Geosciences [3]Beijing General Research Institute of Mining & Metallurgy [4]Institute of Sedimentary Geology,Chengdu University of Technology [5]State Key Laboratory of Oil/Gas Reservoir Geology and Exploitation,Chengdu University of Technology

出　　处：《Journal of Earth Science》2012年第4期442-454,共13页地球科学学刊（英文版）

基　　金：supported by the National 973 Program of China (Nos. 2011CB403102 and 2009CB421002);the SINOPEC Forward-Looking Project (No. YPH08114)

摘　　要：ABSTRACT： The two basalt flows in Kupukuziman （库普库兹满） Formation of Keping （柯枰） area are the typical products of Permian magmatism. Based on systematic field investigations, we carried out geochemical studies on representative Keping basalts. The results show that the SiO2 contents in basalts range from 44.69 wt.% to 51.68 wt.%, and the total alkalis range from 4.05 wt.% to 5.5 wt.%, belonging to alkaline basalts. The Ti/Y=468.27-565.35 and TIO2=（2.88-3.82） wt.% compared to those of the high-Ti basalts in Emeishan （峨眉山） large igneous province （LIP） （TIO2=（3.58-5.21） wt.%, Ti/Y〉500, Xiao et al., 2004）. The contents of MgO and compatible elements Cr （12.9-18.6 ppm）, Ni （13.7-22.7 ppm）, and Co （39.6-50.2 ppm） are low, which suggest that the samples have undergone varying grades of fractional crystallization. All the samples have uniform REE and other trace element characteristics, with enriched LREE and LILE relative to HREE and HFS, similar REE patterns without Eu anomaly. The basalts are also show slightly depleted of Ta and Nb. They have higher initial STSr/S6Sr ratios （0.707 211-0.708 300）, lower tNd（t） values （-2.47 to -4.14）, and a narrow range of （208pb/204pb）t=37.535 2-38.297 7, （207pb/204pb）~=15.435 7-15.517 0, and （206Pb/204pb）t=17.206 5-17.874 7 ratios. The Ce/Y versus Zr/Nb diagram shows that the parent magmas were originated from low-degree partial melting of the garnet-lherzolite. The analysis results based on geochemical studies seem all point to the same conclusion that the Keping basalts have formed as a product of the interaction between the plume-derived melts and the lithosphere.Geochemical Characteristics and Petrogenesis of Permian Basaltic Rocks in Keping Area, Western Tarim BasinABSTRACT： The two basalt flows in Kupukuziman （库普库兹满） Formation of Keping （柯枰） area are the typical products of Permian magmatism. Based on systematic field investigations, we carried out geochemical studies on representative Keping basalts. The results show that the SiO2 contents in basalts range from 44.69 wt.% to 51.68 wt.%, and the total alkalis range from 4.05 wt.% to 5.5 wt.%, belonging to alkaline basalts. The Ti/Y=468.27-565.35 and TIO2=（2.88-3.82） wt.% compared to those of the high-Ti basalts in Emeishan （峨眉山） large igneous province （LIP） （TIO2=（3.58-5.21） wt.%, Ti/Y〉500, Xiao et al., 2004）. The contents of MgO and compatible elements Cr （12.9-18.6 ppm）, Ni （13.7-22.7 ppm）, and Co （39.6-50.2 ppm） are low, which suggest that the samples have undergone varying grades of fractional crystallization. All the samples have uniform REE and other trace element characteristics, with enriched LREE and LILE relative to HREE and HFS, similar REE patterns without Eu anomaly. The basalts are also show slightly depleted of Ta and Nb. They have higher initial STSr/S6Sr ratios （0.707 211-0.708 300）, lower tNd（t） values （-2.47 to -4.14）, and a narrow range of （208pb/204pb）t=37.535 2-38.297 7, （207pb/204pb）~=15.435 7-15.517 0, and （206Pb/204pb）t=17.206 5-17.874 7 ratios. The Ce/Y versus Zr/Nb diagram shows that the parent magmas were originated from low-degree partial melting of the garnet-lherzolite. The analysis results based on geochemical studies seem all point to the same conclusion that the Keping basalts have formed as a product of the interaction between the plume-derived melts and the lithosphere.Geochemical Characteristics and Petrogenesis of Permian Basaltic Rocks in Keping Area, Western Tarim Basin

关 键 词：Tarim basin PERMIAN large igneous province mantle plume geochemical characteris-tics. 

分 类 号：P618.13[天文地球—矿床学]