宁镇山脉岩基岩浆的化学演化

本文根据四个杂岩体中主要矿物的化学成分和全岩主要元素资料,利用T·L·Wright(1984)提供的质量平衡计算程序来模拟它们的成因,然后再用微量元素来检验和完善上述模式。定量模拟结果表明,分离结晶作用是造成这些杂岩体在岩石学和地球化学上分异的主要原因,并可用斜长石,角闪石、黑云母、磷灰石和榍石的分步分离来解释各杂岩体的成分变化,但对每一个杂岩体来说矿物分离比例可大不相同。微量元素的检验结果和主要元素的模拟趋势基本一致,但分离矿物的绝对值可不完全相同。

CHEMICAL EVOLUTION OF MAGMA IN BATHOLITH OF NANJING-ZHENJIANG MOUNTAIN

Using the mass-balance calculation program of T.L.Wright and others (1972) in consideration of chemical composition of major minerals and whole rocks major elements of four granitoid complexes from batholith, the peyrogenesis of these rock units has been modeled. The modle obtained from major elements has been tested by compatibility with trace elements. It can be concluded that fractionnal crystallization is the prime cause of petrological and geochemical differentiation within these complexes. The chemical variations of various complexes can be explained by the batch fractionation of plagioclase, hornblend, biotite, apitite, sphene and magnitite, the fractional proportions of which are quite different for each complex. The fractional crystallization of hornblend and apitite is usualy in the early evolution stage of each complex, while the fractionation of plagioclase is important in the later evolution stage. The fractional proportions of these minerals proposed by two methods of modeling based on major elements and trace elements only reflect the consisterncy of evolutional trend within each complex, but the absolute values can't be entirely the same.