地质通报2015，Vol.34Issue(12)：2203-2218,16.
大兴安岭南段黄岗梁地区早白垩世岩浆作用的时代、成因及其构造意义
Age, petrogenesis and tectonic implications of the Early Cretaceous magma-tism in the Huanggangliang area, southern Da Hinggan Mountains
摘要
Abstract
The Early Cretaceous porphyroclastic lava and K-feldspar granite in the Huanggangliang area of southern Da Hinggan Mountains both yielded LA-ICP-MS zircon U-Pb ages of 137.7 ± 1.2Ma, which represent a widespread magmatic episode in the southern Da Hinggan Mountains. They are characterized by high content of SiO2, K2O and low content of CaO, MgO, and Al2O3 in-dicating high evolution magma. ASI values of the studied rocks are from 1.06 to 1.33, suggesting that they are metaluminous-weakly peraluminous, and belong to the high-K calc-alkaline to alkaline series. The total rare earth elements (ΣREE) vary in the range of 116.98×10-6 to 350.51×10-6, with strong negative Eu anomalies. The samples are enriched in large ion lithophile elements (LILE, e.g., Rb, Ba, Th, U) and high field strength elements (HFSEs, e.g., Nd, Zr, Hf), but depleted in incompatible elements, such as Ba, Sr, P, Ti and Nb. These characteristics indicate that they are mainly highly fractionated I-type granites. The Early Cretaceous magmatism has slightly high whole-rockεNd(t) values (-0.8 to+0.9)and positive zirconεHf(t) values (+1.9 to+18.3), with the young Nd mod-al ages (TDM=993-855Ma) and Hf modal ages (TDM2=888-561Ma), indicating that they were probably derived from juvenile crust, with minor old crustal materials. In view of the regional geology and the magmatic evolution in the southern Da Hinggan Mountains, the authors hold that these Early Cretaceous magmtic activities took place in a regional extensional setting. They were possibly related to the post-orogenic extension under the Mongolia-Okhotsk tectonic regime.关键词
大兴安岭南段/LA-ICP-MS锆石U-Pb年龄/岩浆演化/早白垩世/伸展Key words
Southern Da Hinggan Mountains/LA-ICP-MS zircon U-Pb dating/magma evolution/Early Cretaceous/Extension分类
天文与地球科学引用本文复制引用
赵辉,李舢,王涛,王文志,焦永艳..大兴安岭南段黄岗梁地区早白垩世岩浆作用的时代、成因及其构造意义[J].地质通报,2015,34(12):2203-2218,16.基金项目
国家自然科学基金项目(批准号:41402194)、中国地质调查局项目(编号:12120113013700、12120113013800)和中国博士后科学基金(编号:2015T81073) （批准号:41402194）
