Composition of the peninsular India rivers average clay (PIRAC): A reference sediment composition for the upper crust fr
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Composition of the peninsular India rivers average clay (PIRAC): A reference sediment composition for the upper crust from peninsular India SHAIK SAI BABU1, RAVIPATI VENKATA RAMANA1, VENIGALLA PURNACHANDRA RAO1,*, MEKALA RAM MOHAN2, ARADHI KESHAV KRISHNA2, SARIPOOT SAWANT2 and NANNAPANENI SATYASREE1 1
Vignan’s Foundation for Science, Technology and Research (VFSTR), Deemed-to-be Vignan’s University, Vadlamudi, Guntur District, AP 522 213, India. 2 CSIR–National Geophysical Research Institute, Uppal Road, Hyderabad 500 007, India. *Corresponding author. e-mail: [email protected] MS received 8 July 2019; revised 6 September 2019; accepted 10 September 2019
We present a new dataset on the average composition of the clay fraction of sediments in 13 rivers draining the entire peninsular India, referred to here as Peninsular India Rivers Average Clay (PIRAC). PIRAC showed relatively P low Si and high Fe, Mn and Mg compared to the other reference sediments. The total trace elements ( TE) content of PIRAC was lower than that of Post-Archean average Australian Shale (PAAS), but close P to that of Average Suspended Sediment of World Rivers (ASSWR). The total rare earth elements ( REE) content of PIRAC lower than that of PAAS but close to that of P was slightly P World River Average Clay (WRAC). The TE and REE were much higher for PIRAC than in other reference sediments. Anomalously high Cu, Zn and Pb in PIRAC suggest that these trace elements do not reliably indicate the crustal composition. PAAS-normalised REE of PIRAC showed LREE-depleted, MREE- and HREE-enriched REE patterns with positive Ce and Eu anomalies, suggesting that PIRAC is more maBc than that of PAAS and the clays weathered from volcanic rocks and felsic component of the metamorphic rocks dominated the crustal composition of peninsular India. The REE pattern of PIRAC resembles to that of European Shale (ES) and Mud of Queensland (MUQ) but different from PAAS, WRAC, upper continental crust (UCC) and East China Post-Archean Shale (ECPAS), which exhibit LREE-enriched and HREE-depleted REE patterns. It implies that the REE composition of the upper crust is not uniform and it should be thoroughly investigated to determine the composition of PIRAC with more analyses on sediments for better understanding of the evolution of the crust. Keywords. Upper crust; peninsular India; reference sediment; trace elements; REE.
1. Introduction The upper continental crust (UCC) consists of sedimentary cover (sediments/sedimentary rocks) and the underlying metamorphic or volcanic basement rocks. The geochemistry of the near
surface sediments/sedimentary rocks provides information on the composition of the upper crust and, determining sediment composition has been an important pursuit of geologists for understanding of the chemical evolution of the Earth’s crust (McLennan 2001). Condie (1993) suggested that
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the average major element composition of the upper crust is similar to the averag
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