Foraminifera from the early Danian intertrappean beds in Rajahmundry quarries, Andhra Pradesh

N. Malarkodi, Gerta Keller, P. J. Fayazudeen, U. B. Mallikarjuna

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

Intertrappean beds exposed between upper and lower traps of the Government and Sunnamrayalu quarries of Rajahmundry were analyzed based on benthic and planktic foraminifera, ostracodes and algae observed in thin sections. Planktic foraminifera indicate deposition occurred in the early Danian Parvularugoglobigerina eugubina (Pla) zone shortly after deposition of the lower trap flows. The most diverse planktic assemblages were deposited in limestones of the middle intertrappean interval and indicate an upper Pla age, or subzone Pla(2), as marked by the co-occurrence of P. eugubina, Globoconusa daubjergensis, Parasubbotina pseudobulloides and Subbotina triloculinoides. Reworked late Maastrichtian planktic foraminifera are common in a limestone interval and suggest erosion of uplifted Cretaceous sediments. Benthic foraminiferal assemblages indicate deposition occurred predominantly in shallow inner shelf to brackish environments. Similarly, ostracodes indicate variable environments ranging from inner neritic to brackish with fresh water influx, as also indicated by the presence of fresh water algae. These data confirm an overall deepening from restricted shallow marine to estuarine, lagoonal and finally open marine conditions followed by abrupt emersion and paleosoil deposition prior to the arrival of the upper trap flows at or near the base of C29n.

Original languageEnglish (US)
Pages (from-to)851-863
Number of pages13
JournalJournal of the Geological Society of India
Volume75
Issue number6
DOIs
StatePublished - Jun 1 2010

All Science Journal Classification (ASJC) codes

  • Geology

Keywords

  • Andhra Pradesh
  • Danian
  • Foraminifera
  • Intertrappean
  • Ostracodes
  • Rajahmundry

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