Low latitude Tethyan calcareous nannofossil ocean paleoecology across
the early/middle Eocene transition
Abstract
Calcareous nannoplankton population underwent a major reorganization
across the early and middle Eocene. This reorganization was mainly
explored from an open ocean perspective, but marginal settings are
usually underexplored. Here we analyzed a Tethyan pelagic record from
Avdat, southern Israel in the Levant margin. The calcareous nannofossil
assembledge was then compared to a number of Deep Sea and Ocean Drilling
sites through paleoecological techniques. From calcareous nannofossil
zone NP12 until zone NP15-16 (undiff.), dominance shifted from to
discoasters in the warm early Eocene, and then to responding to cooling
in the middle Eocene. Markers for middle Eocene oceanic destratification
and mixing, e.g., the acme, peak and the first occurrence of , are
delayed by ~1.0 Myr at Avdat with respect to oceanic
sites at comparable paleolatitudes, and more so when compared to higher
latitude sites. The Avdat section is punctuated by peaks of , diversity
of spp., and that were not reported in deep oceanic sites. The
disparities at Avdat vs. other oceanic localities can be ascribed to its
position in a Tethyan remnant ocean surrounded by land masses and
orogenic terrains. The punctuational mode and delay in water
destratification in the Levant ocean are attributed to connection to
warm and saline water off the Afro-Arabian shelf affected by pulses of
cooler waters from Boreotropical marine connections, and sea level fall
late in the Middle Eocene, increasing proximity to shelves.