Palynostratigraphic Constraints on the Upper Tanezzuft and Akakus Formations in the Ghadamis Basin of Libya

Abstract

The Ghadamis Basin in northwest Libya has generated a tremendous amount of oil and gas, sourced primarily from the lower Silurian anoxic black shales (aka ‘hot shales’) at the base of the Tanezzuft Formation. These dark grey, fissile shales contain substantial amounts of organic matter, as well as radioactive minerals. The Silurian System in the Ghadamis Basin consists of both the Tanezzuft and the overlying Akakus formations. Cores and outcrops are difficult to correlate across the basin but can be improved using chitinozoans biostratigraphy. Eighty samples from three wells that collectively cover the entire Silurian in the northeastern Ghadamis Basin yielded a diverse group of marine chitinozoans. Identified species include Ancyrochitina ancyrea, A. fragilis, Sphaerochitin concava, S. sphaerocephala, Fungochitina spinifera, Pseudoclathrochitina carmenchui, and Eisenackitina cylindrica. These species along with others could allow for robust age determination and enhanced stratigraphic correlation between the three wells, which can increase our understanding of the Ghadamis Basin’s paleogeography and paleoenvironments.