Geochemical Characterization Given by Rock‐Eval Parameters and N‐alkanes Distribution on Ypresian Organic Matter at Jebel Chaker, Tunisia

Abstract

Sedimentary rock samples from Jebel Chaker in the eastern part of the Ypresian basin in central-northern Tunisia were analyzed using various geochemical methods in order to decipher their organic signature. Examination of the distribution of total organic carbon (1.04 -1.82%) suggests that the petroleum potential of Ypresian facies is not ignored in such area. The Ypresian episode permitted the accumulation of organic matter, which is typically marine plankton as indicated by the unimodal distribution of N -alkane at n C 18 and by the predominance of the aliphatic hydrocarbons compared to the aromatics. It is concluded that the Ypresian organic matter is relatively immature, as indicated by the high content of polar compounds (3 -67%) in bitumen. This conclusion is supported by the relative low T max values (433 -438°C), suggesting that the organic matter is located towards the end of diagenesis and beginning of catagenesis. These new results testify to the establishment of suboxic conditions that led to the accumulation and preservation of good quantities of organic matter in central-northern Tunisia during the Ypresian. Due to their geochemical characteristics, the Chaker facies represent new potential source rocks in central-northern Tunisia.

Mineralogical and geochemical studies of Ypresian marly clays and silica rocks of phosphatic series, Gafsa-Metlaoui basin, southwestern Tunisia: implication for depositional environment

“…This preservation can be related to an anoxic depositional environment and/or to a high sedimentation rate, which are explained mostly by a high biological productivity. According to Peters et al (2005) Arfaoui and Montacer (2007), the TOC content in the sediments is due to various factors: primary production, preservation rate of organic matter, and rate of organic deposition. The accumulation of high amount of organic matter can also be related to the size of deposit sediments, as reported by Mayer et al (1985) Salamon et al (2000).…”

“…The description of this technique is previously presented in the studies of Arfaoui and Montacer (2007) and Felhi et al (2008b).…”