Gerta Keller Strikes Back: Maastrichtian Cretaceous a High Stress Environment due to Deccan Vulcanism

Late Maastrichtian–early Danian high-stress environments and delayed recovery linked to Deccan volcanism

Authors:

Punekar et al

Abstract:

Deccan volcanism occurred in three intense phases of relatively short duration: phase 1 spanning the paleomagnetic chron C30r/C30n boundary (planktic foraminiferal CF4), phase 2 in the latest Maastrichtian C29r (zones CF1–CF2), and phase 3 in the early Danian C29n (P1b). This study explores the nature of paleoenvironmental changes correlative with the three volcanic phases in central Egypt and the Sinai based on planktic foraminifers, stable carbon and oxygen isotopes.

Results show that high-stress assemblages dominated by Guembelitria blooms are prominent in, but not exclusive to, all three volcanic phases. These blooms are well known from the aftermath of this mass extinction in zones P0–P1a, the intertrappean interval between volcanic phases 2 and 3. Guembelitria blooms in CF4 (phase 1) are relatively minor (less than 45% ) although they comprise a substantial component of the planktic foraminiferal assemblages. Maximum Guembelitria blooms (greater than 80% of the total assemblage) are observed in CF1, which spans the last 160 ka of the Maastrichtian marked by rapid global climatic warming and cooling correlative with phase 2. Major Guembelitria blooms (50–75%) are also observed in P1b, which is marked by climate warming (Dan-C2 event) and a major negative carbon isotope excursion correlative with phase 3. This high-stress event precedes full marine biotic recovery after the mass extinction.