Two types of metamorphism and their relationships with granites in the Mashan Complex
Two types of metamorphism and their relationships with granites in the Mashan Complex
复制标题
马山杂岩两种变质作用及其与花岗岩的关系
DOI：
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发表时间：
2012
影响因子：
1.8
通讯作者：
Gao HongLin
中科院分区：
文献类型：
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作者：
Ren LiuDong;Wang YanBin;Yang ChongHui;Zhao ZiRan;Guo JinJing;Gao HongLin
黑龙江省佳木斯地块马山杂岩发育了两种类型的变质作用。局部早期麻粒岩相变质作用(M1)伴有无流体深熔作用(530Ma)。随后广泛的岩浆作用导致了强烈的混合云作用(500Ma)和相应的晚期角闪岩相变质作用(M2)。前者实际上是高品位的。马山群及其变质岩以散布于晚期混合岩中的残余块体或包体为主。从角闪岩相到麻粒岩相的转变不是过渡性或渐进性的，这表明两种变质作用存在很大差异。混合岩化作用可能是富含流体的，对早期的“干”变质作用发生了实质性的退变蚀变，导致岩石结构复杂。含流体花岗岩的侵位可能会重置早期高级变质作用形成的锆石的U-Pb系，真实的变质年龄难以测定。马山杂岩的变质作用-花岗岩序列与东南极洲普里兹湾带的变质作用-花岗岩序列非常相似。两个地区的变形-变质作用都紧随花岗岩而来。不同的是，两个地区晚期花岗岩化的强度不同。西伯利亚克拉通边缘和中亚带的一些微大陆发生了一些与冈瓦纳边缘相似的构造-热-岩浆事件。也就是说，中亚带的佳木斯地块和其他类似物与冈瓦纳带的泛非带在构造上相似，尽管它们在古代大陆构型上可能属于不同的域。
Two types of metamorphism have been discerned from the Mashan Complex in the Jiamusi Block,Heilongjiang Province,northeastern China.The local earlier granulite facies metamorphism(M1) was accompanied by fluid-absent anatexis(530Ma).The subsequent widespread magmatism was responsible for the intensive migmatization(500Ma) and corresponding late amphibolite facies metamorphism(M2).The former is actually the high grade Mashan Group(s.s.) and the metamorphic rocks are dominated by residual massives or enclaves scattered in late migmatitic granites.The change from amphibolite to granulite facies is not transitional or progressive,suggesting the great difference of the two kinds of metamorphism.The migmatization was probably fluid-rich and made substantial retrograded alteration to the earlier "dry" metamorphics,accounting for the complicated textures of the rocks.In addition,the emplacement of the fluid-bearing granites may reset the U-Pb system of the zircons formed in earlier high-grade metamorphism and the real metamorphic ages could be hardly measured.For the metamorphism-granite sequence,the Mashan Complex is rather similar to that of the Prydz Bay belt of East Antarctica.In both areas the deformation-metamorphism were closely followed by granites.The difference is that the intensity of late granitization varies in the two areas.Along the southern margin of the Siberian Craton and some microcontinents in the Central Asian belt occurred some tectono-thermal-magmatic events similar to that around the Gondwana margin.That is to say,the Jiamusi Block and other analogues in the Central Asian belt are tectonically similar to the Pan-African belts in the Gondwana,though they may belong to different domains in ancient continent configuration.