PALYNOLOGICAL ANALYSIS OF SOME CORE SAMPLES FROM THE NORTHEASTERN EDGE OF SIRT BASIN, LIBYA

Palynological analysis of some core samples from the well T/2D/79/97 which penetrates the Memoniat Formation and the Tanezzuft Formation in the northwestern edge of the Sirt Basin at latitude 30 º 09' 50" N - Longitude 15º 42' 17" E,. indicates the presence of two distinguished assemblages. These were compared with similar assemblages described from other parts of Libya. Shale beds from the lower part of this horizon contain well preserved species of acritharch, such as Baltisphaeridium longispinosus delicatum, B. aliquigranulum, Veryhaqchium irroratum and Villosacapsula steosapelliula. Comparison of this assemblage with those studied by Hill and Molyneux (1988) and Grignani et al. (1991) indicate that this level of the Memoniat Formation belongs to the Ashgillian. Sample from the upper part of the studied horizon are composed of graptolitic shales and contain distinguished species of acritarchs, such as Ammonidium microladium, Cymbosphaeridium pillaris, Leiofusa estrecha, Leiosphaeridia wenlockia and Micrhystridium stellatum, and a small association of chitinozoa composed of Cingulochitina cingulata, Sphaerochitina longicollis and Conochitina convexa. The spore association is more diversified and contains Ambitosporites ambitus, A. avitus, Synorisporites verrucatus. Comparison of this assemblage with the assemblages described by Al-ameri (1983) and Tekbali and Wood (1991) attributes this level of the Tanezzuft Formation to the Wenlockian-Ludlovian. Because the studied borehole is located between the Sirt and Ghadamis basins, it can offer paleogeographic and paleoenvironmental parameters, which can be used in the correlation of oil and water reservoirs.