The Rajahmundry Traps, Andhra Pradesh: Evaluation of their petrogenesis relative to the Deccan Traps |
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| Authors: | Ajoy K Baksi |
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| Institution: | (1) Department of Geology and Geophysics, Louisiana State University, 70803 Baton Rouge, LA, USA |
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| Abstract: | Geochemical and geochronological data for rocks from the Rajahmundry Traps, are evaluated for possible correlation with the
main Deccan province. Lava flows are found on both banks of the Godavari River and contain an intertrappean sedimentary layer.
Based on40Ar/39 Ar age data, rocks on the east bank are post K-T boundary, show normal magnetic polarity, and belong to chron 29N. Their
chemistry is identical to lavas in the Mahabaleshwar Formation in the Western Ghats, ∼1000km away. It was suggested earlier
that the genetic link between these geographically widely separated rocks resulted from lava flowing down freshly incised
river canyons at ∼ 64 Ma. For the west bank rocks, recent paleomagnetic work indicates lava flows below and above the intertrappean
(sedimentary) layer show reversed and normal magnetic polarity, respectively. The chemical composition of the west bank flow
above the intertrappean layer is identical to rocks on the east bank. The west bank lava lying below the sedimentary layer,
shows chemistry similar to Ambenali Formation lava flows in the western Deccan.40Ar/39 Ar dating and complete chemical characterization of this flow is required to elucidate its petrogenesis with respect to the
main Deccan Province. |
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| Keywords: | Flood-basalts geochemistry age plumes intracanyon flows Rajahmundry Deccan |
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