摘要
本次工作研究了柴达木地块和欧龙布鲁克地块中的古元古代莫河岩体、新元古代沙柳河岩体、早三叠世香日德岩体和察汉诺岩体以及晚三叠世可日岩体的主量元素、微量元素和Nd-Sr-Pb同位索组成．沙柳河岩体和可日岩体具S型过铝质花岗岩成因特征，其他岩体具Ⅰ型花岗岩类成因特征．TDM和εNd（t）值的对比揭示，沙柳河岩体的源岩区为欧龙布鲁克地块的Ⅱ型基底变质表壳岩系，其余岩体的岩浆都不可能源自暴露地表的基底变质表壳岩系。花岗岩类和基底变质表壳岩系的亏损地幔最大模式年龄集中在1.5-2．3Ga和0．9～1．3Ga，在欧龙布鲁克地块中亦有～2．5Ga及2．8Ga显示，一般Pb同位素比值（205^Pb/204^Pb）。〉18，（207^Pb／204^Pb）。〉15．5，（208^Pb／204^Pb）。〉38，具高放射成因铅特征．这表明，柴达木地块和欧龙布鲁克地块基底与扬子陆块具有密切的亲缘性，现今的扬子陆块范围可扩大到中国西部阿尔金断裂东、西两侧的微陆块群，昆中断裂带和柴北缘高压-超高压变质岩带代表扬子陆块内部裂解小地块的再汇聚带．
The formation of major and trace-elemental and Sr-Nd-Pb isotopic geochemistries in Early Paleoproterozoic Mohe pluton and Early Triassic Cahanno pluton of the Oulongbuluke micro-block and Neoproterozoic Shaliuhe pluton, Late-Permian to Early-Triaasic Xiangride pluton and Late-Triassic Keri pluton of the Qaidam Block of northwestern China, were investigated. The Shaliuhe pluton and Keri muscovite pluton are characterized by S-type and paraaluminium granite, the others are by Ⅰ-type granodiorite or granite. It is concluded from the comparsion of TDM and εNd （t） that the magma source area of the Shaliuhe granite belongs to the Ⅱ-type metabasement of the Oulongbuluke micro-block, and the magma of the rest of the plutons could not originate from the exposed supracurstal sequences. The TDM are clustered at -1. 5-2. 3 Ga and 0. 9- 1.3 Ca, with peak value of -1.2 Ga, -1.6 Ga and -2. 05 Ga for both granitoids and meta-supracurstal rocks, -2. 5 Ga and -2.8 Ga are solely distributed in the Oulongbuluke micro-block. The two micro-blocks have ratios of （206^ Pb/204^ Pb）,（207 ^Pb/204^ Pb）, and （206^Pb/204^ Pb）, generally higher than 18, 15.5 and 38, respectively. These data suggest that the basements of the Oulongbuluke micro-blocks and the Qaidam micro-blocks are geochemically akin to that of the Yangtze Block, and that the Yangtze Block Domain can be extended northwestwards to the micro blocks on both sides of the Altyn-Tagh fault, and that the UHP-HP tectonic belt along the northern margin of the Qaidam micro-block is only a convergent boundary among the earlier broken-up micro-blocks within the Yangtze Block.
出处
《地球科学（中国地质大学学报）》
EI
CAS
CSCD
北大核心
2007年第1期7-21,共15页
Earth Science-Journal of China University of Geosciences
基金
国家自然科学基金项目(No40234052)
教育部科技重点项目(No104039)
香港大学RGC项目
中国地质大学地质过程与矿产资源国家重点实验室基金项目(NoMGMR2002-29)
