Geology and Structure of the High-Grade Rocks from Punalur-Achankovil Sector, South India
Geology and Structure of the High-Grade Rocks from Punalur-Achankovil Sector, South India
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印度南部普纳鲁尔-阿坎科维尔地区高品位岩石的地质和结构
DOI：
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发表时间：
1990
影响因子：
1.3
通讯作者：
Masaru Yoshida
中科院分区：
文献类型：
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作者：
T. Radhakrishna;J. Mathai;Masaru Yoshida
Punalur-Achankovil地区是南印度高品位麻粒岩地形的西南部分。其特征为绿帘石和石榴黑云母。石英长石（GBQF）片麻岩，少量产状硅线岩、含石墨片麻岩和基性麻粒岩。在结构上。地形经历了三个阶段的强烈变形变质作用和一个后期的不强烈变形作用。第一次变形（d1）破坏了原有的沉积分层，石英长石带发育；伴生变质作用（m1）以麻粒岩相硅石质片麻岩和基性麻粒岩为代表。第二次变形（d2）导致等斜褶皱，相应的变质作用（m2）产生了现在以GBQF片麻岩为代表的大型新体。代表3 - m3事件的岩性为在高变质条件下发育的绿帘岩和小型花岗岩体；“从开到紧”的不对称褶皱是这种变形的特征。最终变形（d4）渗透性较弱，以开褶皱为特征。该地区的构造资料没有显示出任何主要剪切带的特征，也没有像前面所说的那样构成克拉通间缝合带。沿Achankovil-Punalur的地形表现仅为新构造地貌。
The Punalur-Achankovil sector is a southwestern segment of the high-grade granulite terrain of South India. It is characterised by charnockite and garnet-biotite. Quartz-feldspar (GBQF) gneiss with minor occurrences of sillimanite and graphitebearing gneiss and basic granulite. Structurally. The terrain has undergone three phases of intense deformation and metamorphism and a late less intense deformation. The first deformation (D 1 ) has disrupted original depositional layering with development of quartzo-feldspathic bands; the accompanying metamorphism (M 1 ) is represented by granulite facies sillimanite-bearing gneiss and basic granulite. The second deformation (D 2 ) resulted in isoclinal folding and the corresponding metamorphism (M 2 ) produced large neosome now represented by the GBQF gneiss. Lithologies representing the D 3 -M 3 event are the charnockite and minor granite bodies developed under high-grade metamorphic conditions; open to tight" asymmetric folds are characteristic of this deformation. The final deformation (D 4 ) is less penetrative and is characterised by open folds. Structural data from the area do not indicate any major shear zone features nor does the region constitute an intercratonic suture belt as suggested earlier. The topographic expression along Achankovil-Punalur represents only a neotectonic lineament.