南岭西段花山——姑婆山A型花岗质杂岩带:岩石学、地球化学和岩石成因  

The Huashan—Guposhan A-type Granitoid Belt in the Western Part of the Nanling Mountains:Petrology, Geochemistry and Genetic Interpretations

作　　者：朱金初[1] 张佩华[1] 谢才富[1,2] 张辉[3] 杨策[1] 

机构地区：[1]南京大学成矿作用国家重点实验室 [2]中国地质科学院宜昌地质矿产研究所,443003 [3]中国科学院地球化学研究所

出　　处：《地质学报》2006年第4期529-542,共14页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号40373014;40132010和40073008)资助成果。

摘　　要：花山—姑婆山花岗质杂岩带由同安、花山、牛庙、金子岭、乌羊山、里松和姑婆山等岩体所组成,岩性为闪长岩、石英二长岩、二长花岗岩和正长花岗岩等,富含中基性暗色包体,主要侵位时代为160~163Ma。岩带以富碱,高钾,富含Rb、K、Ba、Pb等大离子半径亲石元素(LILE)及富含Th、U、REE、Y、Nb、Ta、Zr、Hf等高场强元素(HFSE)为主要特征。中酸性主岩和暗色包体的ISr值分别在0.70501~0.70742和0.70473~0.70570范围内,εNd(t)值分别在-0.37^-3.21和-0.47^+1.94范围内。这是一个以地幔物质略占优势的A1亚型花岗质杂岩带,其源区物质可能主要是经过交代和富集的具有OIB型微量元素特征的岩石圈地幔和下地壳。在后造山阶段大陆地壳拉张减薄的构造环境下,软流圈地幔沿超壳深断裂的上涌和底侵,导致了强烈的壳幔相互作用,源区物质不同程度、不同深度和多批次的熔融,以及硅酸盐熔浆不同程度的分离结晶和地壳混染,是形成岩带中不同类型中酸性岩浆岩的主要机制。The Huashan—Guposhan granitoid belt consists of Tong＇ an, Huashan, Niumiao, Jinziling, Wuyangshan, Lisong and Guposhan granitoid bodies. Petrographycally, they are diorite, quartz monzonite, monzonitic granite and syenogranite. Dark mafic enclaves are very common. Their major emplacement ages are 160 ～163 Ma. This granitoid belt is characterized by high contents of large ion lithospheric elements （LILE） such as K, Rb, Ba, Pb and high field strength elements （HFSE） such as Th, U, REE, Y, Nb, Ta, Zr, Hr. The ISr ranges for acidic-intermediate host rocks and enclaves are 0. 70501 ～ 0. 70742 and 0. 70473 ～ 0. 70570, respectively, and the εNd （t） ranges for these rock types are -0. 37 ～ -3. 21 and -0. 47 ～ ＋1. 94, respectively. This is an A1 type granitoid belt, slightly predominated by mantle components. Their source regions are probably mainly the lithospheric mantle and lower crust, which had been metasomatized and enriched so that they could bear OIB characters in trace elements. The post-orogenic extension and thinning environment of the south China continental crust, the strong mantle-crust interaction caused by upwelling and underplating of the asthenospheric mantle across the trans-crustal faults, the multi-staged melting of the source rocks in different proportions and at different depths, and the different degrees of fractional crystallization and crustal contamination of the silicate melts are the major mechanisms for generating different types of acidic to intermediate granitoids in the belt.

关 键 词：南岭 花山—姑婆山岩带 A型花岗岩 岩石学 地球化学 岩石成因 

分 类 号：P588.121[天文地球—岩石学]