Microfacies Analysis and Paleontology of Carbonate Rocks in Shanan Section; South Eastern Ethiopia

Beksa, Amente Kumsa (2017) Microfacies Analysis and Paleontology of Carbonate Rocks in Shanan Section; South Eastern Ethiopia. Masters thesis, Addis Ababa University.

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Shanan section is situated in Southeastern Ethiopian plateau has a thick succession of carbonate rocks. These studies generally considered the stratigraphy, paleontology, microfacies analysis, biostratigraphy and determine depositional environments of Shanan section carbonates. Based on thin section analysis of 40 samples collected the compositional and textural types of rocks were studied and grouped into six microfacies associations which are characteristic for lagoon, platform margin, foreshoal and offshore environments. The presences of micritic, bioclastic wackestone and peloidal grainstone microfacies at lower Shanan indicate lagoon deposits. The Bioclastic peloidal grainstone and ooilitic grainstone facies present following the lagoon facies carbonates are indicators of carbonate shoal/barrier deposits of shallow marine setting .The middle Shanan layers conformably overlies the lower Shanan and consists of the foreshoal microfacies of thick, allochemical rich wackestone-grainstone limestone’s, mainly dominated by reworked intraclastic grains. A low energy deposit of offshore environment is characterized by fine grained dark gray blackish micritic limestones with some cherts present at upper Shanan section. The overall microfacies and facies successions throughout the unit show that the environments ranges from lagoon, high energy platform margin carbonate sand bodies, foreshoal deposits and offshore deposits successively from bottom to top. Based on the presence of index fossils of Pfenderina cf.salernitana and Kurnubia palastiniensisthe age of this carbonate rocks determined to be Callovian to Oxfordian time. Paleontological study of Shanan section shows that the carbonates are rich in macro and microfossils that supply additional data for stratigraphic and paleoenvironmental interpretations. Eoguttulina polygona, Lenticulina subalata, Lenticulina quenstedti, Verneuilinoides minuata, Haplophragmoides bartensteini and Choffatella.sp, are species of foraminifera collected also 5 genera of ostracods such as, Cytherelloidea.sp., Progonocythere.sp., Procytheridea.sp., Bairdia.sp, and Paracypris.sp are identified. From macrofossils different species of bivalves, gastropods and brachiopods are also identified.The carbonate deposits of the section are correlated with some of equivalent deposits in Southeastern plateau and major regional sedimentary basins ofEthiopia.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Depositional Environment, Fossil, Microfacies, Paleontology, Shanan section, Southeastern Ethiopia.
Subjects: Q Science > Q Science (General)
Q Science > QD Chemistry
Q Science > QE Geology
Q Science > QH Natural history
Divisions: Africana
Depositing User: Selom Ghislain
Date Deposited: 13 Sep 2018 07:45
Last Modified: 13 Sep 2018 07:45
URI: http://thesisbank.jhia.ac.ke/id/eprint/5161

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