學術資源整合系統-相關推薦

 
作者Tung, kuo-An;Tseng, Chien-Yuan
出版日期201912
已接受20191119
著作名稱Nd-Sr Isotope and Geochemical studies of Basement Rocks and Granitoids in the South Qilian Area, NW China
刊名Collection and Research
2019
32
主題地質;岩石礦物
關鍵字Sr-Nd Isotope, Geochemical, Basement rocks, Granitoids, Qilian Block
摘要The Qilian Orogeny Belt is situated between the Sino-Korean plate and the Qaidam plate. Its Precambrian strata are mainly composed of thick volcanic rocks and sedimentary rocks. During the Caledonian orogeny, the fold faults are uplifted and subjected to medium-pressure facies. The highly metamorphic deformation is accompanied by the intrusion of medium-acid plutonic rocks.
The study focused on the basement rocks, granitoids and mafic rocks collected from the middle part of the South Qilian area, nearby Qinghai Lake, Gahai, Wulan and Riyueshan and their main and trace elements, Sr-Nd isotopes are analyzed in hope of making a preliminary discussion on the source, age and thermal events of the base rock in the South Qilian area.
Based on the results of geochemical and isotope analysis, it is found that the basement rocks of Gahai and Riyueshan are in the range of Nd isotope value (εNd (1 Ga) is between -14.8 and -7.6) and have the same characteristics in trace elements. The trend is obviously different from the base rock in the Wulan area (εNd (1 Ga) is between -8.4 and 2.2), therefore, it is presumed that the Gahai and Riyueshan areas belong to the same plate, with an age of about 1.4 Ga, and the Wulan area is another plate, which was about 1.7 Ga, and was affected by three thermal events in about 1 billion years, 500 million years and 280 million years ago, and can be compared to the Jinning, Caledonian and Hercynian periods.
In addition, the geochemical analysis results, field observations, and lithofacies descriptions of granites can be roughly classified into I-type and S-type granites, and the granites collected in Gahai and Riyueshan areas belong to Caledonian S-type granite, while the granite in the Wulan area is an I-type granite with an age of 1.6 Ga, roughly the same as that of basement rocks.
系統號NO000005411

Aug 16 2018 10:46:44
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