Microfacies analysis, sequence stratigraphy, and depositional environment of Eocene deposits: A case study from Samawa desert, Southwestern Iraq

The facies analysis of the Eocene rocks found in South Samawa has led to the identification of two significant Eocene formations: the Rus and Dammam. The Dammam Formation holds substantial geological importance due to its extensive coverage across much of southern Iraq, serving as a primary source for the region's aquifers. Rocks consisting of porous limestones and dolomitic limestones. The microfacies analysis revealed five distinct textures including floatstone, rudstone, wackestone, packstone, and mudstone. These textures are classified into nine sub-microfacies. The Rus Formation with mixed carbonate-evaporitic units has deposited in an inner ramp setting from the lagoon to the sabkha sub environments. In contrast, the Dammam Formation has been deposited in various settings, including a peritidal, lagoon, shoal, restricted marine platform, and open marine inner platform. Six distinct depositional sequences are identified within the formation, each reflecting varying depositional environments. Sequence A, dating to the Lower Eocene, with lagoon microfacies indicating the Maximum Flooding Surface. Sequence B, also from the Lower Eocene, is marked by alternating limestone types and an MFS defined by shallow open marine microfacies. Sequence C, representative of the Middle Eocene, reveals a transition from shoal to peritidal facies. Sequence D, spanns the end of the Middle Eocene to the early Late Eocene. In contrast, Sequence E, representing the Upper Eocene, exhibits transitions from lagoonal to peritidal microfacies. Finally, Sequence F, dating to the Lower Euphrates. Overall, the findings highlight the complex interplay of sea-level changes and tectonic processes in shaping the sedimentary architecture of the Dammam Formation.

کلیدواژه ها:

Eocene ، Rus Formation ، Dammam Formation ، Sequence stratigraphy ، Microfacies ، Palaeoenvironment ، Iraq