大洋斜长花岗岩成因研究现状评述

作为地球上分布最广泛的岩石类型,花岗岩类的研究在地质领域中的作用越来越突出,同位素技术和实验岩石学的发展更是为其研究的深入提供了条件.大洋斜长花岗岩作为花岗岩大类的一个重要分支,受到了广大地质学者的关注.现在学者们对于大洋斜长花岗岩的认识已经不再局限于产出于蛇绿岩中的小规模浅色岩脉,大洋斜长花岗岩还可以以规模较大的独立岩株的形式出现.但其成因目前仍然存在较大分歧,主要有以下三种模型:(1)玄武质岩浆结晶分异模型;(2)辉长岩部分熔融模型;(3)岩浆不混溶模型.最近的实验研究成果表明,不同成因的大洋斜长花岗岩TiO2含量不尽相同,部分熔融作用形成的大洋斜长花岗岩TiO2含量低,而结晶分异和不混溶作用形成的花岗岩类有较高的TiO2含量.这一发现将对大洋斜长花岗岩的研究提供新的思路.

The Study About Petrogenesis of Ocean Plagiogranite

As the most extensive rock on earth,Granites play an important role in the field of geology.The development of isotopic technology and rock experimental study provide a condition for the study of granite.Plagiogmite is an important branch of Granites,which also catches the attention of a lot of geologists,and at the same time many encouraging results emerge.Now the understanding of the scholars is no longer limited by the small amounts of leucocratic vein in ophiolites.Actually,plagiogranite can occur in the form of pluton.However,the petrogenesis of plagiogranite are different.Three major models are under debate:(1)fractional differentiation of MORB melt,(2)partial melting of gabbric rocks,(3)immiscibility in liquid.Recently,experiments different style of ocean plagiogranite has different TiO2 content.TiO2 is relatively low in melts generated by anatexis of gabbros,and TiO2 is relatively high in those melts generated by MORB differentiation or liquid immiscibility.This method will provide a new way for the study of ocean plagiogranite.