The macroscopic Paleo-pedogenic features and their significance in deducing the continuity of sedimentation and the climatic changes during the Eocene/Oligocene transition, Dur At Talah sequence, central Libya

International audienceThe studied sequence is 150 m thick of siliciclastic strata, well-exposed as a prominent escarpment that extends along 25°:45ʺN at the southern flank of Sirt Basin and dated as of Late Eocene age. It is built up from the base to top by three sedimentary units: (i) very fine sandstones and mudstones called New Idam Unit (NIU), (ii) medium-grained sandstones called Lower Sarir Unit (LSU) and (iii) very coarse to microconglomeratic sandstones called Upper Sarir Unit (USU). Pedogenic modifications which are differentially recurring from the base to the top of this sequence have not been paid sufficient attention in the previous studies. This study benefited the widespread macroscopic pedogenic features, introduced them and discussed their usefulness for estimating the continuity of the sedimentation and thus inferring the paleoclimate responsible for their formation. The exposed pedogenic features characteristic of each unit are described and then discussed in light of the documented modern and ancient analogues and case studies in order to comprehend the depositional continuity through time. The discussion is passed via analysing the prevailed climate because it is the fundamental factor controlling the formation of these features. Ultimately, this research allowed, for the first time, the recognition of a major (end Eocene) unconformity embedded within the sequence. This is certainly of interest for the hydrocarbon exploration in and around the basin

Crayfish fossil burrows, a key for indentification of terrestrial environments in tide-dominated sequence, Upper Eocene, Sirt Basin, Libya.

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