Productivity and bottom water redox conditions at the Cenomanian- Turonian Oceanic Anoxic Event in the southern Tethyan margin, Tunisia
Year: 2011
Type: article
Abstract: In Tunisia, five Bahloul spaced sections, Bargou, Jerisa, Guern Halfaya, Kherij and Gafsa were analysed for major and trace elements. These high-resolution chemostratigraphic integrated analyses for the Late Cenomanian-Early Turonian Bahloul Formation provide new insight on the palaeoceanographic evolution of the southern Tethyan margin. Relative low abundance of related terrigenous Ti/Al and K/Al ratios and enrichment of some productivity proxies such as Ba, Cu, and Ni (organic matter related trace elements) suggests that the Bahloul, deposited during a relative short period (400 kyr), was of relatively elevated primary productivity and minimal detrital input. While higher D* values concurrent with lower Ti/Al ratios are interpreted as caused by enhanced fluvial material contribution, due to more humid climate during the OAE-2. Enhanced humidity triggered probable fluvial influxes, resulted in a sluggish water circulation and consequent anoxic/euxinic conditions favouring the preservation of organic matter at the sea floor. Enrichments in redox-sensitive trace metals U, V, and Mo in the Bahloul Formation deposits and redox indices, such as V/(V+Ni), U/Th, V/Cr, and Ni/Co, indicate that oxygen-restricted conditions prevailed during the Late Cenomanian - earliest Turonian times. High Baxs values and Uauth may indicate anoxic conditions at least at the water-sediment interface during the Bahloul Formation deposition and provide information about low to moderate sulphate-reduction reactions.
Author: Mohamed Soua
Language: English
Subfield: Paleontology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2170124754