大别山核部九资河花岗岩体成因  

Petrogenesis of Jiuzihe granites in the core of Dabie Mountains

作　　者：王强[1] 王人镜[2] 邱家骧[2] 赵振华[1] 桑隆康[2] 胡正祥 戴圣潜 何涌[2] 周国华[2] 许卫 王建新 齐先茂 张顺金 

机构地区：[1]中国科学院广州地球化学研究所,广东广州510640 [2]中国地质大学,湖北武汉430074

出　　处：《地球化学》2000年第2期120-131,共12页Geochimica

基　　金：原地质矿产部基础研究项目资助!H50E006007;H50E006008;广东省自然科学基金博士启动项目!994588

摘　　要：对大别山核部九资河花岗岩进行了岩石学、稀土和微量元素地球化学、同位素地球化学研究，讨论了其侵 位特征、成因和构造意义。九资河花岗岩的 ＡＮＫ＝ １． １５～１． ４５（平均１． ２８），ＡＣＮＫ＝０， ９１～１． １０（平均 １． ００）， δＥｕ＝ ０．３６～１．１６，ε_（Ｎｄ）（ｔ）＝－１６．５，ε_（Ｓｒ）（ｔ）＝５９．１。九资河花岗岩体为一沿ＮＥ向剪切带就位的原地．半原地花岗岩体，与 世界典型的原地－半原地深熔花岗岩体相比，九资河花岗岩体具有这些花岗岩体的一般特征：出现于高级变质区， 与围岩呈渐变过渡或侵入关系，岩石属于亚碱性系列的钙碱性岩系，但岩性复杂，具有片麻状或条带状构造，矿物残 留结构发育，围岩无热变质，残留的暗色包体特别多，侵入岩在Ｒｂ－Ｂａ－Ｓｒ图解中成分范围一致，岩浆演化方式为“残 留体模式”。不同点在于九资河花岗岩为偏铝质－过铝质之间的过渡类型，且为Ⅰ型花岗岩，其他的为过铝质Ｓ型花 岗岩。这种差别的原因在于九资河花岗岩的源岩以变质火成岩──ＴＴＧ片麻岩为主，而其他花岗岩的源岩为变质沉 积岩。九资河花岗岩不是“变质或交代”成因，而是由深熔作用形成，源岩中斜长石和黑云母的熔融反应控制了熔融 过程。The characteristics of emplacement, petrogenesis and tectonic implications of Jiuzihe granites are studied by petrology, REE and trace element geochemistry, and isotope geochemistry. The Jiuzihe granites have the following geochemical characteristics: ANK = 1. 15 - 1. 45 (average, 1. 22), ACNK = 0. 91 - 1. 10 (average, 1. 00), δEu = 0. 36 - 1. 16, ε_(Nd)(t) = - 16. 5, ε_(Sr)(t) = 59. 1. Jiuzihe pluton is an in situ-parautochthonous intrusive body along NE shear zones. Jiuzihe pluton and typical in situ-parautochthonous plutons in the world share many characteristics: (1) the plutons occur in the regions with high grade metamorphic rocks, and have graduational or intrusive relationships with country rocks; (2) the granites are cafe-alkalic rocks of sub-alkalic series, but their lithology is very complex; (3) the rocks develop gneissosity and banded structure, and there are many residual minerals in the rocks; (4) the country rocks have not the phenomena of thermal metamorphism; (5) a lot of relic mianthites develop; (6) in the diagram of Ba-Rb-Sr, the rocks have the same range of compositions; (7) the modes of magmatic evolution are 'residual model'. There are also a few differences between Jiuzihe granite and the typical in situ-parautochthonous granites in the world: Jiuzihe intrusive rocks show transitional characteristics between metalumious rocks and peraluminous ones and are I granites. but others are peraluminous rocks and S granites. It is due to the different source rocks of Jiuzihe and other granites. The source rocks of Jiuzihe granites are TTG gneisses with crust-mantle origin, but those of other typical in situ-parautochthonous rocks are metasediments. Jiuzihe granites are not formed by 'metamorphism or metasomatism', but by anatexis. The melting reactions of biotites and plagioclase control melting processes. The dynamic setting of anatexis can be delamination. North Dabie Block is not a magmatic complex that formed by magma ascending and emplacing along tensile space in Cretaceous period.

关 键 词：花岗岩 岩石成因论 原地深熔作用 构造意义 

分 类 号：P588.121[天文地球—岩石学]