engleski

The upper Oligocene and lower miocene of the western part of the Tripolitania basin (Libya) : biostratigraphy and paleoecology

Exploration off-shore well NC-167 was drilled in the pelagic shelf area in the northwestern part of Tripolitania Basin, Libya. A detailed investigation, based on planktonic and benthonic foraminifera, has been carried out on ditch samples. Lithologically, in the Oligocene and Miocene, packstone and wackestone limestones prevailed with rare fragments of boundstone limestones. The boundary between the Upper Oligocene and Lower Miocene was determined by planktonic foraminifera and large benthonic foraminifera were important indicators of paleoenvironment. Sediments were deposited in the shallow shelf. In the Upper Oligocene, significant index fossils are Globigerina ciperoensis Bolli and Globorotalia nana Bolli. Small benthonic foraminifera (Asterigerina) and larger foraminifera (Lepidocyclina, Heterostegina, Spiroclypeus, Operculina, etc.) were determined. Lower Miocene sediments contain the planktonic foraminifera Globoquadrina dehiscens Bolli, and others, along with the larger foraminifera (Operculina) and small benthonic foraminifera (Asterigerina, Cibicidoides, Elphidium, etc.). Besides foraminifera, debris of corrallinacean algae, bryozoan and spines o echinoderms have also been observed.

foraminifers; stratigraphy; tertiary

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