高校地质学报Issue(1)：123-132,10.
白云鄂博中二叠世巴音珠日和岩体地球化学特征及构造意义
Geochemical Characteristics of Bayinzhurihe Pluton and Its Tectonic Significance, Bayan Obo, Inner Mongolia
摘要
Abstract
The middle segment of northern margin of the North China Plate was influenced by intense tectonic and magmatic activity during the Permian. Dozens of intrusions formed an E-W trending magmatic belt that extended from the Dongshenmiao to Xianghuang Qi, Inner Mongolia, with a length of 400 km and width of 30 km. As a representative, Bayinzhurihe Pluton consists of quartz diorite and hornblende gabbro, which belong to high-potassium calc-alkaline series. They are characterized by low SiO2 (49.72%~59.34%) and high Al2O3 (15.79%~19.50%) contents, with Mg#=38~44, enrichment in large ion lithophile elements (LILE, e.g., Ba=829×10-6~1104×10-6, Sr=502×10-6~726×10-6), relative depletion in high field strength elements (HFSE, e.g., Nb, Ta) in primitive mantle-normalized spidergrams, and right-inclined rare earth element patterns, mostly with slightly negative Eu anomalies (δEu=0.63~1.09). Their low Sr/Nd ratios (12~24) and La/Nb ratios (1.33~2.39) may reflect intraplate magmatism involved. Hornblende gabbro shows non-arc-like (Nb/Th =9.6-18.4) basalt affinity compositions. LA-ICP-MS U-Pb zircon dating of the Pluton yielded an intrusive age of 265±2Ma. Its zircons haveεHf(t)=-13.0~-17.2 and t DMC=2.12~2.38 Ga, mainly show the characteristics of lower continental crust. These features lead us to conclude that Bayinzhurihe Pluton was generated by mixing of lower crustal-derived mafic melt and minor enriched mantle-derived mafic magma, followed by fractional crystallization, due to crustal extension in post-collisional setting.关键词
锆石LA-ICP-MS U-Pb定年/Hf同位素组成/后碰撞/华北板块北缘Key words
zircon LA-ICP-MS U-Pb dating/Hf isotopic compositions/post-collision/northern margin of the North China Plate分类
天文与地球科学引用本文复制引用
罗红玲,吴泰然,赵磊,贺元凯,荆旭..白云鄂博中二叠世巴音珠日和岩体地球化学特征及构造意义[J].高校地质学报,2013,(1):123-132,10.基金项目
国家自然科学基金项目(40902065和40672146)和中央高校基本科研业务费资助 （40902065和40672146）
