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The origin and tectonic setting of precambrian greywacke of Ribandar-Chimbel, Goa, India: Petrological and geochemical evidence

DRS at CSIR-National Institute of Oceanography

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Title The origin and tectonic setting of precambrian greywacke of Ribandar-Chimbel, Goa, India: Petrological and geochemical evidence
 
Creator Fernandes, G.Q.
Iyer, S.D.
Kotha, M.
 
Subject Geology and geophysics
Geology and geophysics
Geology and geophysics
 
Description The Precambrian greywacke of Ribandar-Chimbel belonging to the Sanvordem Formation of the Goa Group, India, has been studied for petrography and analyzed for major trace elements. The greywacke is characterized by angular to sub-round grains of quartz, feldspar, biotite, chlorite and clay minerals. The abundance of clay in the matrix seems to have influenced the Al2O3 content and the K2O/Al2O3 ratio. The variation diagrams indicate a decreasing trend of TiO2, Al2O3, Fe2O3 and MgO; whereas Na2O and CaO exhibit a scatter which could be a result of the variable presence of feldspar within the sediments. The immobile elements, vanadium (25 to 144 ppm), nickel (up to 107 ppm) and chromium (up to 184 ppm), reflect abundance of clay minerals. The greywacke shows strongly fractionated REE patterns with LaN/YbN = 8 to 26 and with higher total REE abundances (up to 245 ppm). The low REE enrichment and depletion in heavier REE with prominent negative Eu anomaly (Eu/Eu*= 0.54 to 0.79) suggest a derivation of the greywacke from an old upper continental crust composed chiefly of felsic components. Petrological evidence and geochemical data suggest that the deposition of the greywacke largely took place in a deep to shallow basin that progressively changed from that of a continental island arc to an active continental setting
 
Date 2017-03-03T08:43:14Z
2017-03-03T08:43:14Z
2016
 
Type Journal Article
 
Identifier Acta Geologica Sinica, vol.90(6); 2016; 2036-2048
http://drs.nio.org/drs/handle/2264/5110
 
Language en
 
Publisher Geological Society of China