内蒙古贺兰山地区古元古代晚期的花岗岩浆事件及其地质意义:同位素年代学的证据  

Late-Paleoproterozoic granite events and their geological significance in Helanshan area, Inner Mongolia: Evidence from geochronology.

作　　者：耿元生 周喜文 王新社 任留东 

机构地区：[1]Chinese Acad Geol Sci, Inst Geol, Beijing 100037, Peoples R China

出　　处：《岩石学报》2009年第8期1830-1842,共13页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(40672126);地质大调查项目(1212010611702)资助

摘　　要：位于华北克拉通西缘的贺兰山杂岩主要由孔兹岩系和变形花岗岩(正片麻岩)所组成,前者主要由夕线石榴片麻岩、石榴二长片麻岩、变粒岩和少量的大理岩及麻粒岩所组成,后者主要包括黑云斜长片麻岩、石榴子石花岗岩、斑状花岗岩和片麻状变质闪长岩。本文报道了该区变形花岗岩的锆石SHRIMP U-Pb定年结果。黑云二长片麻岩和石榴子石花岗岩分别形成于2053±58Ma和2047±42Ma,斑状花岗岩和片麻状闪长岩分别在1955Ma和1920Ma侵位。大量的年代学资料表明,在华北克拉通北缘存在一条古元古代晚期的花岗杂岩带,该带中的花岗杂岩主要形成于三个阶段,第一阶段大于2.0Ga,第二阶段主要出现在2.0～1.87Ga期间,第三阶段的花岗杂岩在1.85～1.80Ga期间侵位。年代学研究还表明,古元古代晚期的花岗岩浆作用常常与变质事件紧密相关。Helanshan complex, situated in the western margin of the North China Craton, consists mainly of khondlite series and deformed granitoids (orthogneisses). The former is composed dominently of sillimanite-garnet gneiss, garnet two-feldspar gneiss, leptineite and a bit of marble and granulite, the later consists mainly of biotite plagioclase gneiss, garnet granite, porphyritic granite and gneissic diorite. By using the zircon SHRIMP U-Pb dating, the authors have been obtained some results for granitoids in this area. The biotite feldspar gneiss and garnet granite formed respectively 2053 +/- 58Ma and 2047 +/- 42Ma, respectively, porphyritic granite and gneissic diorite intruded at 1955Ma and 1920Ma respectively. A lot of geochronology data indicate that a Late-Paleoproterozoic granite zone distributes in the northern margin of the North China Craton. The Late-Paleoproterozoic granitoids formed in three stages, the granitoids of the first stage formed early than 2.0Ga, second stage occurred in 2.0 similar to 1.87Ga, the granitoids in third stage intruded at 1.85 similar to 1.80Ga. The Late-Paleoproterozoic granitoids in the Helanshan area formed mainly at first and second stage. In the north margin of the North China Craton, Late-Paleoproterozioc granite magmatism accompanied usually by regional metamorphism in time.

关 键 词：内蒙古 贺兰山地区 古代晚期 岩浆事件 地质意义 同位素年代学 证据 area North China Craton 变形花岗岩 黑云斜长片麻岩 花岗杂岩 regional metamorphism 华北克拉通北缘 stage 石榴子石 黑云二长片麻岩 zircon SHRIMP 闪长岩 片麻状 

分 类 号：P58[天文地球—岩石学]