摘要
本文指出,五台山西部角闪岩相变质的繁峙群属于太古代花岗绿岩带性质,其中的变质火山岩具有由拉斑玄武岩向钙碱性系列演化特性.与该群相伴生的花岗质岩石,包括了云英闪长岩—奥长花岗岩和钙碱性二个演化系列,在西田可见到繁峙群不整合于灰色片麻岩(T、T、G 岩套)之上.该区曾经受多期构造变形,早期以岩浆底辟及水平挤压褶皱作用为主,形成卵形花岗岩穹窿、向形盆地和韧性断裂;晚期受区域水平挤压作用,产生大规模的叠加褶皱,构成现今的线状构造及推覆构造.
The area where the amphibolite-facies rocks of the Fanshi Group are distributed in Mount Wutai is an Archean granite-greenstone terrane.By means of the petrological-structuralmapping of the western part of Mount Wutai,the Fanshi Group is divided into three petrological-structural units The metavolcanic rocks of the Fanshi Group reflect an evolution from the tholeiite series toealc- alkaline series.The granitic rocks (with an isotopic age of over 2500 Ma) in the area of distribution of the Fanshi Formation fall into two evolutionary series: the tonalite-trondhjemite series and the talc-alkaline series.The infracruatal rocks consist of gray gneisses (T.T.G.) suite and the supracrustal rocks are made up of the Fansi Group of the greenstone belt,with the supracrustal rocks overlying unconformably the infraerustal rocks (Xitian).The granites and part of granodiorite were emplaced as a diapir.The magmatie diapirism and subhor- izontal shearing combined to form oval granite domes and linear synformal basins. In the synformal basins there are recumbent folds and subhorizontal ductile faults formed by gravity sliding.The late-stage regional horizontal compression caused the domes and basins to be refolded and flattened and brought about large- scale overlapping deformation,thus forming the present linear structural belt and nappe structure.
出处
《中国区域地质》
CSCD
1990年第2期132-139,共8页
Regional Geology of China
