东北地区显生宙花岗岩的成因与地壳增生

Petrogenesis of the Phanerozoic granites and crustal growth in Northeast China.

东北地区显生宙花岗岩极为发育，特别是中生代印支—燕山期岩体分布面积巨大，可称之为巨型花岗岩省。其主要的成因类型是Ｉ－分异型和Ａ－型，而Ｓ－型花岗岩极为少见。区域地质分析表明，这些花岗岩的主体是在古亚洲域洋壳消失后形成的，其成因与由大量板块俯冲而导致的区域深部热异常或地幔柱有关。从地球化学特点上看，这些花岗岩主要表现为低的初始锶（ＩＳｒ≈０．７０５）和高初始钕（εＮｄ（ｔ）＞０，显示其形成与地幔关系密切。对其年轻的钕模式年龄（ｔＤＭ＜１０００Ｍａ）的分析表明，地质历史上的新元古代－显生宙也是地壳增生的重要时期；同时，垂向增生也是地壳生长的重要机制。

The NE China is characterized by the widespread Phanerozoic granitic intrusions, most of them are of Mesozoic Indosinian Yanshanian, which can be described as Large Granitic Province. The studies of petrology and geochemistry show that most of these granite are fractionated I and A type, but the S type is rarely seen. According to the results of regional geology and isotopic dating, the Indosinian Yanshanian granites in this area were formed after the closure of Paleo Asian Ocean , we suggest a correlation between the formation of this huge area of granites with the deep mantle heat anomaly or mantle plume resulting from the subduction . Geochemically, a striking feature of these granites is their low value of I Sr (≈0 705) and high value of ε Nd ( t ) (positive), which indicate a close relationship to the mantle. The young Nd modal age (<1000Ma) suggests the Neoproterozoic Phanerozoic is also one of the main stages in the continental growth, and the crust can also be greatly thickened that via vertical regime.