LARGER BENTHIC FORAMINIFERA FROM THE PANNA AND MUKTA FIELDS OFFSHORE INDIA: PALEOBIOGEOGRAPHICAL IMPLICATIONS

摘要

A previously undocumented, diverse assemblage of very shallow-water larger benthic foraminifera (LBF) is described from the Panna-Mukta fields, offshore India. This location lies at the margin of the late Eocene to early Miocene Arabian Peninsula marine biodiversity hotspot. The assemblage has similar characteristics to those from the Middle East, Oman and Turkey, but shares little in common with onshore western Indian assemblages. In addition, the material contains several unusual and possibly new taxa, and extends the geographic ranges of several existing LBF. The succession spans the Eocene and Oligocene, with an unconformity between the middle and upper Eocene. As such it offers insight into the response of shallow-water taxa to the Eocene-Oligocene Transition extinction event from an unusual setting in a little studied region. Our data show that LBF taxonomic richness in the Panna Mukta fields is comparable with highly diverse assemblages found in Oman, indicating it may be an eastward extension of this high diversity region. Moreover, significant decreases in diversity are seen between the middle and upper Eocene and the upper Eocene and Oligocene. Major extinctions are known to occur in global LBF records at both of these levels, and the Panna Mukta succession therefore further confirms these are global events, extending across the platform and having a dramatic (at least short-term) effect on high biodiversity regions.