Middle to Late Triassic Granitoids in the l:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />Qimantage Area, Qinghai Province, lace w:st="on">Chinalace>: Chronology, Geochemistry and Metallogenic Significances

详细信息   

• 责任者：Feng Chengyou (Key Laboratory of Metallogeny and Mineral Resource Assessment ; MLR ; Institute of Mineral Resources ; CAGS ; Beijing 100037 ; China) ; Wang Song
• 刊名：Acta Petrologica Sinica
• 出版年：2012
• 卷期：28(2)
• 关键词：花岗岩 ; granite ; 多金属矿 ; polymetallic ores ; 青海 ; Qinghai Province
• 页码：p.665-678
• 图表：8 illus., 4 tables, 23 refs.
• 分类号：1001
• issnNo：ISSN1000-0569
• isbnNo：CN11-1922/P

摘要

 The Qimantage area,located on the southwestern margin of Qaidam Basin,is not only a characteristic intrusive magmatic tectonic belt,but also a very important poly-metallic metallogenic belt.In this paper,detailed geochronological,element geochemical,Sr-Nd-Pb isotopic studies were carried out for the Middle to Late Triassic granitoids,and relationship between granitoids and poly-metallic mineralization was discussed.The Middle to Late Triassic granitoids in Qimantage area are characterized by the metaluminous to peraluminous and high-K calc-alkaline rocks.Of them,the Late Triassic granitoids is much enriched in K₂O/Na₂O ratio,LILE and LREE,and poor in HFSE.The rocks exhibit moderate initial ⁸⁷Sr/⁸⁶Sr values and comparatively negative εNd(t) values,which indicate that they were derived from ancient crust sources and mixed probably by mantle material.The precise U-Pb zircon dating results define emplacement of the mianthite-riched granodiorite occurred during 230～237Ma,Late Triassic porphyritic granitiods intruded at 228～204Ma.It is inferred that the tectonic transformation from crustal compression to extension was produced at about 240Ma,and was accompanied by mantle source magmatism.The occurrence of Late Triassic high differentiated and high-K calc-alkaline granitoids indicates that this area had evolved into post-collisional environment.The large numbers of porphyry and skarn-type poly-metallic deposits are temporally and spatially related to Middle to Late Triassic granitic intrusions.