Recognition of depositional environment of the Gurpi Formation based on palynofacies in compared to field studies and sedimentary microfacies analysis in northeast Izeh

Ghasemi-Nejad, Ebrahim; Beiranvand, Bijan

Recognition of depositional environment of the Gurpi Formation based on palynofacies in compared to field studies and sedimentary microfacies analysis in northeast Izeh

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Abstract

Â This investigation is an integrated of full field descriptions of lithology, sedimentary structures, ichnofacies, stratigraphic surfaces and natural gamma ray loging and detailed sedimentary and palynological microfacies analysis to identify depositional environment of the Gurpi Formation in northeast Izeh. A total of 148 samples were collected from the studied section to prepare palynological slides (80 samples) and thin sections (68 samples). Â The results of the field study and sedimentary micofacies analysis indicate a low energy, disoxic to anoxic, relatively deep marine carbonate system with partially terrestrial organic matter for the Gurpi Formation. On the other hand, the palynofacies analysis indicates that the main components of the sedimentary organic matter are amorph organic matter (AOM), phytoclasts, palynomorphs (POM), and minor amounts of foraminiferal test linings and the other palynological elements. However, based on the aboundance of the palynological elements and using the Tyson's Triplot to represent the data, three main palynofacies zones of VI, VIII, and IX were recognized. Distribution of the data in these three palynofacies zones obviously indicates a disoxic to anoxic proximal to distal shelf conditions. In addition, the presence of thermal index dynocysts in the sediments reveals a tropical to subtropical warm Tethyan outer shelf environment of deposition for the succession in the Late Cretaceous to Paleocene.

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