Systematic geochemical studies have been conducted on the North Küda Pluton, West Kunlun, in order to reveal its petrogenesis and tectonic implications. The North Küda Pluton is a potassium\|rich (K\-2O>5...Systematic geochemical studies have been conducted on the North Küda Pluton, West Kunlun, in order to reveal its petrogenesis and tectonic implications. The North Küda Pluton is a potassium\|rich (K\-2O>5.4wt%) I\|type granitic pluton and does not contain any alkaline ferromagnesian mineral. Its relatively high REE, LILE (e.g. Rb, Cs, U and Th) and HFSE (e.g. Nb, Zr) contents make it very akin to the A\|type granites. Its heterogeneous Sr (\{\{\}\+\{87\}Sr\}/\{\{\}\+\{86\}Sr\-i\}=\{0.7049\}～\{0.7098\}) and Nd (εNd\-T=\{-1.05\}～\{-4.04\}) isotope compositions preclude the possibility of a pure sedimentary or igneous source. Instead, its geochemical compositions suggest that it may be derived from partial melting of a complex source, which consists of igneous and sedimentary rocks. Its intraplate characteristics, together with coeval mafic dykes, indicate an extensional environment at the end of Caledonian. The recognition of the extensional event does not support a continuous subduction\|accretion model for the Paleozoic tectonic evolution of the West Kunlun Mountains. On the contrary, it provides new evidence for the two\|stage island\|arc model.展开更多
文摘Systematic geochemical studies have been conducted on the North Küda Pluton, West Kunlun, in order to reveal its petrogenesis and tectonic implications. The North Küda Pluton is a potassium\|rich (K\-2O>5.4wt%) I\|type granitic pluton and does not contain any alkaline ferromagnesian mineral. Its relatively high REE, LILE (e.g. Rb, Cs, U and Th) and HFSE (e.g. Nb, Zr) contents make it very akin to the A\|type granites. Its heterogeneous Sr (\{\{\}\+\{87\}Sr\}/\{\{\}\+\{86\}Sr\-i\}=\{0.7049\}～\{0.7098\}) and Nd (εNd\-T=\{-1.05\}～\{-4.04\}) isotope compositions preclude the possibility of a pure sedimentary or igneous source. Instead, its geochemical compositions suggest that it may be derived from partial melting of a complex source, which consists of igneous and sedimentary rocks. Its intraplate characteristics, together with coeval mafic dykes, indicate an extensional environment at the end of Caledonian. The recognition of the extensional event does not support a continuous subduction\|accretion model for the Paleozoic tectonic evolution of the West Kunlun Mountains. On the contrary, it provides new evidence for the two\|stage island\|arc model.
