Crystalline basement and Precambrian crustal growth of the continental massifs within the Central Asian Orogenic Belt(CAOB) are still pending problems. Our geological and geochemical investigations identified an Arche...Crystalline basement and Precambrian crustal growth of the continental massifs within the Central Asian Orogenic Belt(CAOB) are still pending problems. Our geological and geochemical investigations identified an Archean(2606 Ma) granitic pluton in the Biliya area of the Erguna Massif. The Neoarchean granitoids show high and positive in-situ zircon ε_(Ht)(t)(+0.3 to +10.0), whole-rock ε_(Nd)(t)(+4.8) and whole-rock ε_(Ht)(t) values(+2.1). They are characterized by high Y + Ce + Zr + Nb(> 220 ppm) and Zr contents and could be classified as A-type granites. These granitoids are characterized by high Zr saturation temperatures(T;)(796–836°C). They were derived from partial re-melting of juvenile mafic lower crust in an intracontinental back-arc extensional environment. This newly identified Neoarchean granitic pluton may represent the crystalline basement of the several continent massifs within the CAOB, and their high ε_(Ht)(t)–ε_(Nd)(t) values may also indicate the occurrence of lateral crustal growth events in these massifs during the Neoarchean.展开更多
基金financially supported by Geological Survey projects of China Geological Survey (DD20160047 and 12120115031301)。
文摘Crystalline basement and Precambrian crustal growth of the continental massifs within the Central Asian Orogenic Belt(CAOB) are still pending problems. Our geological and geochemical investigations identified an Archean(2606 Ma) granitic pluton in the Biliya area of the Erguna Massif. The Neoarchean granitoids show high and positive in-situ zircon ε_(Ht)(t)(+0.3 to +10.0), whole-rock ε_(Nd)(t)(+4.8) and whole-rock ε_(Ht)(t) values(+2.1). They are characterized by high Y + Ce + Zr + Nb(> 220 ppm) and Zr contents and could be classified as A-type granites. These granitoids are characterized by high Zr saturation temperatures(T;)(796–836°C). They were derived from partial re-melting of juvenile mafic lower crust in an intracontinental back-arc extensional environment. This newly identified Neoarchean granitic pluton may represent the crystalline basement of the several continent massifs within the CAOB, and their high ε_(Ht)(t)–ε_(Nd)(t) values may also indicate the occurrence of lateral crustal growth events in these massifs during the Neoarchean.
