摘要
以鼓山－魁岐、青田和普陀山－桃花岛三个典型岩体为例，系统研究了浙闽沿海Ｉ型－Ａ型复合花岗岩体的地质和地球化学特征。研究结果表明：复合岩体中Ｉ型与Ａ型花岗岩在主量、微量和稀土元素特征上均存在明显变异。总体而言，Ａ型花岗岩较之Ｉ型花岗岩富硅、富碱、贫钙、镁、铝，并具偏高的Ｒｂ／Ｓｒ、Ｒｂ／Ｂａ、Ｇａ／Ａｌ和偏低的ＬＲＥＥ／ＨＲＥＥ比值及显著的铕负异常。两类花岗岩的Ｎｄ、Ｓｒ同位素组成均具有壳幔混熔岩浆的特点，但仍存在一定的变异。上述变异既有岩浆分异演化的影响，又有幔源岩浆卷入的贡献，在不同的复合岩体中起主导作用的因素各不相同。通过对岩石产出动力地质背景的全面分析，结合本区不同复合岩体中二类花岗岩具不同地球化学变异特点的地质事实，提出浙闽沿海Ｉ型－Ａ型复合花岗岩是区域构造应力、断裂构造。
The geological and geochemical characteristics of the I and A type composite granites along the coastal area of Zhejiang and Fujian province have been studied systematically by citing the three typical rock masses of Gushan Kuiqi, Qingtian and Putuoshan Taohuadao as instances. Investigation resuits have shown that the features of major elements, trace elements and rare earth elements between the I type and A type granites are quite different. Compared with the I type granites, the A type granites are generally rich in sillicon, alkali, poor in calcium, magnesium, aluminum, and have higher Rb/Sr, Rb/Ba,Ga/Al, and lower LREE/HREE ratios and display obviously negative europium anomaly. Nd Sr isotopic compositions between them also show some differences although both of them have similar features to that of the magma derived from partial melting of crustal mantle mixing materials. These differences above are caused both by differentiation and by involvement of mantle derived magma, but only one of them plays the leading role in the formation of the I and A type composite granites. By analysing their occurring tectonic setting comprehensively and considering the fact that the geochemical variation tendency in different I and A type composite granite is different, this paper concludes that the I and A type composite granites in the studied area are products affected jointly by regional tectonic stress, deep faults, involvement of mantle derived magma and differentiation of primary magma.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
1999年第2期237-246,共10页
Acta Petrologica Sinica
基金
国家自然科学基金
关键词
I型-A型
复合花岗岩
地球化学
岩石成因
花岗岩
I and A type composite granite,Geological and geochemical characteristics,Petrogenesis,The coastal area of Zhejiang and Fujian province
