溧阳盆地金山花岗岩地球化学特征及构造意义  

Geochemical characteristics and their geological implications of the Jinshan granites in the Liyang Basin

作　　者：黄顺生[1] 杨用彪[1] 田春明[1] 王海欧[1] 徐旭峰[1] 

机构地区：[1]江苏省地质调查研究院,江苏南京210049

出　　处：《地质学刊》2016年第1期15-22,共8页Journal of Geology

基　　金：中国地质调查局项目"长江中下游成矿带地质矿产调查"(1212011120855)

摘　　要：金山地区处于下扬子与江南隆起的过渡带,区内侵入岩岩石类型主要有花岗斑岩、石英闪长斑岩。岩石地球化学分析结果表明金山花岗岩为高钾钙碱性、准铝质岩浆岩,Si O2质量分数为65.11%~71.40%,K2O/Na2O比值为1.30~2.56,铝饱和指数（A/CNK）集中于1.02~2.05。稀土元素属轻稀土富集型,轻重稀土分异明显,富集K、Rb、Th、U、K、Nd、Zr,亏损Ba、Nb、Ta、Sr、P、Ti,无明显负Eu异常。区域构造背景、岩石学和元素地球化学特征综合分析显示,研究区处于由挤压向拉张转折的转换阶段,花岗岩的形成与幔源物质底侵引起的下地壳物质部分熔融形成的岩浆分异结晶作用有关。The Jinshan area is located in the transitional zone between the Lower Yangtze region and Jiangnan uplift, and the intrusive rocks consist of granitic porphyry and quartz diorite porphyry. Petrochemical studies show that the Jinshan granites are high-K calc- alkaline and metaluminous magmatie rocks, with SiO2 content of 65.11% - 71.40%, K2O/Na2O ratios of 1.30- 2.56, and A/CNK ratios of 1.02-2.05. The granitic rocks are LREE-enriehed, with high ratios of LREE/HREE, and are enriched in K, Rb, Th, U, K, Nd and Zr, depleted in Ba, Nb, Ta, Sr, P and Ti, with no significant negative Eu anomalies. Comprehensive regional geological setting, lithology and geochemical characteristics suggest that the tectonic mechanism of this area is converting from compression to extension, and that the granites mostly originated from partial mehing of lower crust as a resuh of decompression and experienced the magmatie evolution of crystallization and differentiation.

关 键 词：地球化学特征 花岗岩 构造环境 溧阳盆地 江苏 

分 类 号：P588.121[天文地球—岩石学]