Zircon U-Pb Dating and Geochemistry of Late Triassic Intermediate Dykes inSuyingdi, Eastern Section of West Kunlun and Their Geological Significance
Li Youwei
Wei Qirong
Wang Cheng
Ding Pengfei
Liu Xiaonian
Zhang Xiaoqiang
Wang Jingyuan
Liu Wenping
Nong Mingzhi
Abstract：order to understand tectonic-magmatic evolution of eastern section of West Kunlun orogen, a systematic field geological surveying, microscopic petrographic examination, LA-ICP-MS U-Pb zircon dating, and geochemistry study were carried out for the Suyingdi dykes.These dykes occur in groups or belts along an NE trending.The rock types of dykes include (garnet-bearing) diorite-porphyrite, hornblende andesite-porphyrite, and proterobase spessartite.Using LA-ICP-MS method, zircons in the (garnet-bearing) diorite-porphyrite samples show a weighted average age between 214±1 and 219±1Ma, indicating that they formed in Late Triassic epoch, and they are probably tectonic-magmatic products of late period of Indosinian.The rocks belong to the calc-alkaline series, showing intermediate Si (SiO2=53.92%-62.95%), high Al (Al2O3=15.99%-17.69%), rich in Na (Na2O=2.63%-6.09%, Na2O/K2O=1.09-8.30), Ti(Ti2O=0.50%-0.76%), P(P2O5=0.14%-0.23%).The rocks also show a large range of Mg (Mg#=37.73-59.32), and their A/CNK values vary from 0.92 to 1.36.They show enrichment in LREE, Rb, Th, U, K;depletion in HREE, Nb, Ta, Ti, P;(La/Yb)N=7.24-20.02 and weak Ce and Eu anomalies.Suyingdi intermediate dykes are the product of crustal-mantle magma mixing which caused by back-arc extention of eastern section of West Kunlun in Late Triassic.
Keywords：intermediate dykezircon U-Pb datinggeochemistrytectonic settingWest Kunlungeochronology
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：18( 909-926 )