对壳幔二元混合模型的讨论

壳幔二元混合模计算结果的意义是多解的。对该模型所获得的“壳幔比”,并不象一些研究者所认为并强调的那样具有定量意义。所以,将f_M视为岩浆形成时地幔物质直接参与的质量比是不正确的;实质上,它只能被用来定性地反映岩浆源区岩石的成熟程度。

DISCUSSION ON MEANING OF THE CRUST-MANTLE BINARY MIXING MODEL

At present, it is imprecise for application of the crust-mantle binary mixing model and for explanation of fM in generation of intermediate-acidic igneous rocks. On the one hand, owing to have poor geological envidences to prove that a given magmatic body is originated by interaction of the depleted mantle with the upper crust, meaning of result calculated oy the binary mixing model is not confirmed; on the other hand, it is also no correct to connect forming of most intermediate-acidic magmatic rocks with isotopic composition rangng from that of the depleted mantle to the upper crust with direct action of mantle materials. We consider, with the exception of a very few magmas originated from mantle source and contaminated by the upper crustal materials, that the result of calculation, for most intermediate-acidic rocks in the earth's crust, have no quantitative meaning as thought and emphasized by many reseachers. A large amount of facts indicate that direct source of intermediate-acidic rocks distributed widely in continent is crust and no mantle, therefore so-called "crust-mantle ratio" is only used to reflect qualiatively maturity of source rocks.