Geochemistry and strontium isotopic composition of basahs from the Eastern Deccan volcanic province, India

• Main Authors: P. Oliver, Alexander, Dalim K. Paul
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarc*; Antarctica
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.614.824; http://www.minersoc.org/pages/Archive-MM/Volume_41/41-318-165.pdf

s u M M A R Y. Ten rather uniform tholeiitic basalt flows totalling a thickness of 190 m from Sagar, India, contain two stratigraphical breaks. Major element variation allows the flows to be grouped into two eruption cycles. Due to intraflow variation, however, chemical composition is unlikely to be useful in widespread correlation of flow sequence. The initial sTSr/SeSr ratios vary from o'7o39 to o'7o84 with Rb and Sr averaging 6'5 and I84 ppm respectively and Rb/Sr ratios ranging from 0-o02 to 0.224, with no systematic relationship between the initial a~Sr/SsSr ratios and other chemical parameters. Bulk crustal contamination is considered unlikely; selective introduction of sTSr from the granitic basement is postulated. THE DECCAN is one of the largest continental basaltic provinces with an area of about Io • ro 5 sq. km. The rocks are uniform in mineralogy and chemistry over most of the area, being tholeiitic, but diverse types are present in the western part of the province. Conse-quently, geochemical studies have been carried out in the isolated centres in the western part (Chatterjee, 1964; Krishnamurthy, r974; Sukeshwala nd Poldervaart, i958; West, I958). The basalt thickness in the eastern part is only about too to 2oo m, increasing westward to more than 2oo0 m (Bose, I972). Although Sr isotope studies have established similarity or otherwise of the Mesozoic tholeiites of Tasmania, Antarctica, South America (Compston et al., I968)