New Planktonic Foraminiferal Assemblages from the K/T Boundary in the Lurestan area, Zagros Basin, SW Iran: A Preliminary Report

A detailed analysis on the planktonic forminiferal assemblages proves a continuous depositional rate throughout the uppermost maastrichtian to lowermost paleocene in the lurestan area , zagros basin , sw iran. The presence of some well preserved and diversified species abathomphalus mayaroensis , contusotruncana contusa , pseudoguembelinahariaensis, pseudotextularia elegans trinitella scotti which become extinct at the end of the maastrichtian stage and also appearance of some new species (parvularugeglobigerina eugubina, praemurica pseudoinconstans, eoglobigerina eobulloides , globanomalina archeocompressa , globoconusa daubjergensis , subbotina triloculinoides ) which appear from the lowermost paleocene , allow us to separate the cretaceous -tertiary K/T boundary without any discontinuity. this new investigation reveals that only the presence of the abathomphalus mayaroensis zone is not as reliable criteria for continuity between the cretaceous and tertiary as stated by previous researches. this paper provides and introduces a new biozonation scheme based on the planktonic forminifera for the upper part of the gurpi formation in the studied area.

Keywords:

cretaceous , tertiary K/T boundary , new biozonation , planktonic foraminifera , gurpi formation , sw iran.