晋北娄烦吕梁群变质相带的划分及其成因研究  

The Study on the Designation of the Metamorphic Belts and Their Genesis in Liiliang Groups in Loufan Districts Shanxi Province

作　　者：卢保奇[1] 王赐银[2] 

机构地区：[1]上海大学材料科学与工程学院,上海201800 [2]南京大学地球科学系,江苏南京210093

出　　处：《地球学报》2003年第4期325-329,共5页Acta Geoscientica Sinica

基　　金：国家自然科学基金资助项目(批准号:49372102)资助。

摘　　要：晋北娄烦吕梁群由一套经受过两期不同性质变质作用的泥砂质岩、基性火山岩和酸性流纹岩组成。早期为吕梁期变质作用,其结果使该区地层构造形迹总体上呈NE走向;晚期为西川河韧性剪切断裂所产生的区域变质作用,其结果使该区地层走向由早期的NE向扭转为近SN向,且使地层层序发生倒转,并与递增变质带的形成关系密切。选取该区中对变质温度和压力变化反映较敏感的原岩为泥砂质岩石的袁家村组和裴家庄组地层为研究对象,采用电子探针微区分析(EPMA)对沿地层走向上连续分布的特征变质矿物及矿物共生组合特征进行研究,并利用矿物对地质温度计估算该区不同采样点的变质温度和压力条件,对研究区进行变质相带的划分,确定各变质相带的变质温、压条件,并探讨其成因。研究结果表明,袁家村组和裴家庄组为等化学系列地层。沿该地层走向上:西川河断裂以北地区,从北向南,特征变质矿物绿泥石、黑云母、石榴石、十字石和蓝晶石依次规律出现;西川河断裂以南地区,红柱石和夕线石依次规律出现。根据特征变质矿物的空间分布规律、首次出现的地点及矿物共生组合特征,划分出5个变质带:绿泥石带、黑云母带、石榴石带、十字石-蓝晶石带和红柱石-夕线石带。这一完整的递增变质带可与苏格兰高地的巴罗型相媲美。The original layers of metamorphic rocks of Luliang group in Loufan district Shanxi province consist of the muddy sedimentary and igneous rocks, which had undergone the two different metamorphisms, namely: the early Liiliang metamorphisms and the late fault-type ductile shear deformation metamorphisms. The former caused the northeast layer s occurrence, while the latter had the northeast layer's occurrence turned to the nearly north-south and overlapped on the former and closely linked to the formation of metamorphic belts. The author chooses the muddy sediment sensitive to T and p as the subject to study. To designate the metamorphic belts of the metamorphic rocks involved and determine the T and p of the respective metamorphic belts, EPMA and geother-mormetry are adopted in the research. The five metamorphic belts (Chlorite belt→Biotite belt→Almandine belt→ Staurolite and Kyanite belt→ Andalusite and Sillimanite belt) have been designated based on the sequences of the characteristic metamorphic minerals appearing firstly in distribution in the research area. The result shows that there exists the set of complete progressive metamorphic belts that is comparable to the famous Barrovian type in Scotland. Moreover, the metamorphic conditions in the belts are different : the North is controlled by higher pressure( p = 300-700 MPa), while the South by higher temperature( T = 600 ℃ , p < 300 MPa), both of which are attributed to the fault-type ductile shear deformation of Xichuan river.

关 键 词：递增变质带 特征变质矿物 等化学系列 地质温度计 西川河韧性剪切断裂 

分 类 号：P588.3[天文地球—岩石学]