闽北前寒武纪变质岩的P-T-t轨迹和其形成的动力学过程  

P-T-t Paths and Geodynamic Implication of Precambrian Metamophic Rocks in Northern Fujian

作　　者：梅华林[1] 庄建民[2] 杨传夏 

机构地区：[1]天津地质矿产研究所,天津300170 [2]福建省区域地质调查队,三明365001

出　　处：《福建地质》1993年第3期182-194,共13页Geology of Fujian

摘　　要：闻北前寒武纪变质岩是华夏古陆基底的重要组成部分。本文通过对闽北麻源群和马面山群变质岩详细的变质变形关系的研究和石榴子石环带测定P-T-t轨迹的应用,结合构造地质和同位素年代学的资料,证实了麻源群变质岩形成于早元古代或更老年代,在早元古代末期遭受过中压、中高温变质,但在晚元古代晋宁期与中元古代形成的马面山群岩石一起经历了强烈的变质变形作用,表现为早元古代麻源群岩石遭受强烈改造,具有早期地壳再活化特点。麻源群岩石完整的晋宁期变质P-T-t轨迹不支持正常大陆碰撞的假说,它的形成与异常的地幔热流有关,很可能为一种地壳增厚和地幔减薄的动力学模式。The Precambrian metamorphic rocks in Northern Fujian are the important part consisting of the Cathaysian palaeocontinental basement. Based on the detail studies of relationship between metamorphism and deformation of Mayuan Group (early Proterozoic) and Mamianshan Group (late Proterozoic)in Northern Fujian and P-T-t paths determinated from the zoned garnets, as well as the data of structural geology and isotopic geochronology, it is proved that the metamorphic rocks of Mayuan Group formed in early Proterozoic or before early Proterozoic and experienced the metamorphism of the middle pressure and middle-high temperatures in the end of early Proterozoic, and that during late-Proterozoic (Jinning Stage) they experienced the strong metamorphism and deformation together with the rocks of Mamianshan Group, which show that the rocks of Mayuan Group suffered from the intensive deformation and possess the features of early crustal reactivation. The integrated P-T-t paths of the Jinning period metamorphism for the rocks of Mayuan Group suggest that the normal continental collision be impossible in the area. Finally, the authors provide an alternative model of crustal thickening and mantle thinning as explaining the Jinning period metamorphism and deformation in Fujian Province.

关 键 词：动力学 前寒武纪 变质岩 地质构造 

分 类 号：P588.3[天文地球—岩石学]