Paleontology and Biostratigraphy of the Jurassic Carbonate Unit, Lemi -Alem Ketema Section, Central Ethiopia
| dc.contributor.advisor | Balemwal Atnafu | |
| dc.contributor.author | Zekiyat Shemsu | |
| dc.date.accessioned | 2025-08-31T23:33:40Z | |
| dc.date.available | 2025-08-31T23:33:40Z | |
| dc.date.issued | 2023-05 | |
| dc.description.abstract | A study was conducted on the Jurassic carbonate unit in two sections along the Lemi–Alem ketema road across the Jemma River in the Blue Nile Basin. The unit hasn't been researched in terms of age, facies, depositional environment, and calcareous microfossil studies. Therefore, this study aimed to assess the biostratigraphy, facies, paleontology, and depositional environment of the carbonate unit in the Jemma sections. Detailed morphological descriptions, laboratory preparations, microscopic examinations and comparisons of the reported specimens with varieties of photos, field observations and measurements were used to achieve the objectives. Based on lithofacies analysis the carbonates in the study area were categorized into six types. They are fossiliferous marly limestone, coquina, bioclastic limestone, micritic limestone, marly limestone, and clayey marl. Based on petrographic examination nine microfacies were identified. These are bioclastic mudstone, bioclastic wackstone, non-laminated homogenous mudstone, bioclastic rudstone, pelbiopackstone, coated and rounded bioclastic packstone, bioclastic packstone, sandy limestone and marl-limestone alteration. The paleontological investigation of the studied sections indicated that the carbonates are abundant in macro and micro-fossils which provide information for biostratigraphic and paleoenvironmental interpretations. For biostratigraphic interpretations, index fossils of foraminifera assemblages; Kurnubia palastiniensis (Kp), Anchispirocyclina lusitanica (Al), Kurnubia wellingsi (Kw), Nautiloculina oolithica (No), Alveosepta jaccardi (Aj), Pfenderella arebica(Pa), Siphovalvulina variabilis(Sv), Valvulina lugeoni (Vl), Redmondoides lugeoni (Rl), Conicokurnubia orbitoliniformis (Co) and, Everticyclammina virguliana(Ev)were used. One index fossil from dasyclad green algae, Clypeina jurassica (Cj) was used. According to the index fossils, the Jemma sections of Antalo limestone are dated from Callovian to late Tithonian. Microfacies association indicates a depositional environment of the carbonate unit was deposited in a range of environments, that are open marine, shoal, lagoon, and tidal flat. | |
| dc.identifier.uri | https://etd.aau.edu.et/handle/123456789/7280 | |
| dc.language.iso | en_US | |
| dc.publisher | Addis Ababa University | |
| dc.subject | Biostratigraphy | |
| dc.subject | Blue Nile Basin | |
| dc.subject | Depositional Environment | |
| dc.subject | Index Fossil Lithofacies | |
| dc.subject | Microfacies | |
| dc.title | Paleontology and Biostratigraphy of the Jurassic Carbonate Unit, Lemi -Alem Ketema Section, Central Ethiopia | |
| dc.type | Thesis |