万洋山—诸广山加里东期花岗岩的形成机制——微量元素和稀土元素地球化学证据

ON THE GENESIS OF CALEDONIAN GRANITOID ROCKS AT WANYANGSHAN AND ZHUGUANGSHAN, SOUTHEAST CHINA: EVIDENCE FROM TRACE ELEMENTS AND RARE-EARTH ELEMENTS GEOCHEMISTRY

系统的微量元素和稀土元素地球化学研究和模式计算表明,万洋山—诸广山加里东期花岗岩的母岩浆是区域前震旦基底岩石经过80％部分熔融形成的。母岩浆通过40％的分离结晶形成花岗闪长岩;残余岩浆继续演化,经过约50％的分离结晶形成二长花岗岩;最后的残余熔体再分异、固结形成黑云母花岗岩、钾长花岗岩和花岗细晶岩。

Systematic trace and race-earth elements geochemical studies suggest that fractional cry-stallization was a dominant magmatic process during the formation of the Caledonian grani-toid rocks at Wanyangshan and Zhuguangshan. Quantitative model calculations indicate thatthe primary granitic magma was derived fron 80% partial melting of the regional pre-Si-nian basement rocks. About 40% fractional crystallization of the primary magma produced thegranodiorite. The residual magma evolved contineously and finally produced the monzoniticgranite through 50% fractional crystallization. Biotite granite, K-feldspar granite and granite-aplite were produced through fractional crystallization and consolidation of the latest high-evolved residual melt.