Paleoenvironment of the Eastern Tethys in the Early Paleocene

Abstract

Paleoenvironmental conditions of the early Paleocene eastern Tethys have been inferred based on carbonate sedimentation, biostratigraphy, and planktic foraminiferal assemblages of five sections from the Negev of Israel. In the earliest Paleocene at least three intervals of erosion or nondeposition of sediments have been identified (K/ T, PO/Pla, Pla/Plb boundaries) in addition to a black pyriteand organic-rich clay layer about 1.5 to 3.0 m above the KIT boundary (Subzone Pl b/P1c, upper Chron 29N). These hiatuses appear to be widespread and correlate with global sea level fluctuations. Danian planktic foraminiferal assemblages of the eastern Tethys are dominated by alternating abundance maxima between triserial (Guembelitria) and biserial (Woodringina, Chiloguembelina) species. Biogeographic distribution of these taxa indicates that both groups thrived in shallow continental shelf regions. Moreover, abundance maxima of triserial taxa seem to correspond to 613C depletion intervals, which indicate low surface productivity, whereas abundance maxima of biserial taxa correspond to enriched 613C intervals which imply high surface productivity. These paleoceanographic changes may be related to sea level highand lowstands during the earliest Paleocene. Stable isotope analyses of Danian species will be necessary to confirm these observations and to reconstruct oceanic conditions in both open marine and continental shelf regions of the early Paleocene.