DECLINE AND RECOVERY OF LAGENIDE FORAMINIFERS DURING THE END-PERMIAN MASS EXTINCTION AND ITS AFTERMATH (EVIDENCE FROM THE CENTRAL TAURIDES, TURKEY)

Upper Permian (Changxingian) rocks in the Antalya and Aladag nappes (Central Taurides, Turkey) are inner platform bioclastic limestones with a diverse assemblage of lagenide foraminifers. Lagenide diversity drops appreciably in the uppermost 0.5m of the Permian, coincident with an abrupt facies change from skeletal wackestones and packstones to oolitic grainstones. The Permian-Triassic boundary in this region is an unconformity marked by erosional truncation and vadose diagenetic alteration of the underlying oolites. Basal Triassic (Griesbachian) strata are stromatolites (16-18m) that contain parvus Zone conodonts and a disaster assemblage of cornuspirid and earlandiid foraminifers, but only rare, poorly preserved lagenides. Only three of >20 lagenide species from the Permian persisted across the erathem boundary. For the non-survivors, plots of stratigraphic abundance versus distance of last occurrence below the boundary exhibit hollow distribution curves indicative of sudden extinction, as predicted by empirical tests of the Signor-Lipps effect. No lagenides were recovered from Griesbachian oolites (9-29m) that overlie the stromatolites, and no more than four species were recovered from the succeeding 900m of upper Induan, Olenekian and Anisian strata (alternating carbonates and siliciclastics, locally conglomeratic and plant-bearing). Slightly greater Olenekian-Anisian lagenide diversity has been documented elsewhere (e.g., Bulgaria), suggesting that our meager recovery may be attributable to unfavorable lithologies. Clearly, however, lagenide diversity comparable to that of the Late Permian was not achieved again until post-Anisian times.