Facies Analysis and Paleontology of Carbonate Sedimentary Rock in Hagere-Selam, Messobo and Wukro Stratigraphic Sections; Northern Ethiopia, Tigrai: Implication for Depostional Environment Reconstruction and Age Determination.

No Thumbnail Available

Date

2018-05-02

Journal Title

Journal ISSN

Volume Title

Publisher

Addis Ababa University

Abstract

There Is Carbonate Unit Deposited In The Mekelle Outlier During The Upper Jurassic Period As A Result Of Flooding Of The Area By Paleotethys Ocean Toward The Southeast Direction. The Mekelle Outlier Is Situated In The Northern Most Part Of Northwestern Plateau (NWP) And The Study Carbonate Successions Are Aligned Along The Western (Hagere-Selam), Southeastern (Messsobo) And Northeastern (Wukro Section) Margin Of The Mekelle Outlier. This Study Focused On Detailed Investigation Of Facies Analysis And Paleontology Of The Upper Jurassic Carbonate Units In Order To Obtain A Detailed Picture Of Depositional Environment, Age Determination And Correlation. Three Main Methods Were Implemented In Order To Accomplish The Stated Research Problem And Objective Of The Present Study. These Are Pre-Fieldwork, A Detailed Main Fieldwork And Laboratory Analysis (Petrographic Analysis, Micro And Macro Fossil Description And Systematics And Microfacies Analysis). A Total Of 65 Rocks And 26 Productive Dry Marl Sediment Samples Are Collected From The Study Sections And Examined Under Petrographic Microscope. Lithostratigraphically, The Carbonate Succession Has A Total Thickness About 400m, Which Is Characterized By Thin-Thick Bedded Limestone, Mudstone, Fossiliferous, Coquinoidal, Oolitic And Sandy Limestone With Different Skeletal Components And Different Sedimentary Structures. Based On A Detailed Field Investigation, Paleontological And Petrographical Information, 19 Microfacies Type Are Recognized. These Are Grouped Into Four Microfacies Association Including Tidal Flat (MFT1-3), Lagoon (MFL1-2), Shoal (MFS1-6) And Open Marine Environment (MFO1-8). Therefore, The Depositional System Of The Carbonate Succession Represents A Homoclinal Ramp Setting Because Of Thier Wide Lateral And Vertical Distribution Of Facies. Additionally, The Carbonate Units Of The Study Area Are Affected By Different Diagenetic Features Including Compaction, Cementation, Dissolusion, Micrtization, Dolomitization, Neomorphism, And Silicification. The Carbonate Rock Units Are Correlated Within Different Measured Sections In The Mekelle Outlier And Regionally Correlated With The Antalo Limestone Of Blue Nile, The Urandab Formation Of Ogaden, The Antalo Limestone Of Eretria And Other Arabian Platforms Based On Biostratigraphy And Lithostratigraphy.

Description

Keywords

Stratigraphy, Microfacies Analysis, Age, Paleontology, Depositional Environment, Diagenesis, Mekelle Outlier

Citation

Collections