首页   按字顺浏览 期刊浏览 卷期浏览 Collision tectonics in the late Precambrian Eastern Ghats Mobile Belt: mesoscopic to sa...
Collision tectonics in the late Precambrian Eastern Ghats Mobile Belt: mesoscopic to satellite‐scale structural observations

 

作者: T.R.K. Chetty,   D.S.N. Murthy,  

 

期刊: Terra Nova  (WILEY Available online 1994)
卷期: Volume 6, issue 1  

页码: 72-81

 

ISSN:0954-4879

 

年代: 1994

 

DOI:10.1111/j.1365-3121.1994.tb00635.x

 

出版商: Blackwell Publishing Ltd

 

数据来源: WILEY

 

摘要:

ABSTRACTRegional mapping of a section across the Eastern Ghats Mobile Belt (EGMB) north of the Godavari graben in Eastern Peninsular India by using Landsat Thematic Mapper data enables recognition of a number of shear zones, lineaments, and structural domes and basins. A conspicuous megashear occurs at the western boundary of the granulite facies rocks of the EGMB adjacent to the Archean granite‐greenstone craton. The confinement of a suite of alkaline igneous rocks to this shear zone is a notable feature. The strike extensions of this shear belt extend through to the Elchuru alkaline complex, Prakasam District, Andhra Pradesh, and the syenite plutons of Koraput district, Orissa. The contrasting lithologies, metamorphism and structural history on either side of the shear zone suggests that it might be a Precambrian suture zone.The mesoscopic structural features in the EGMB include prominent foliation with moderate to steep dips, folds, faults/shears, S‐C fabrics, pinch and swell structures and other linear fabric elements. These observations favour the consideration of drastic crustal shortening and thickening and a complex deformational sequence. The major rock units in this part of EGMB comprise garnetiferous sillimanite gneisses, quartzites and calc‐granulites forming the khondalitic suite of rocks and a wide variety of charnockitic rocks. The contact of the two rock units is generally sheared and often migmatised.The structural fabric suggests two major tectonic events: an essentially horizontal tectonic regime resulting in thrust systems and associated structures, subsequently followed by strike‐slip tectonics characterized by high shear strains. Features such as westward‐verging thrusts, large‐scale recumbent folds, major shear zones, structural domes and basins, indications of tectonic crustal shortening, extensive calc‐alkali magmatism and widespread migmatization in the region are attributed to collisional processes during Proterozoic times. The spatial disposition of the EGMB and its linkage with the distribution of similar rock units during the late Precambrian time in a global tectonic scenario

 

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