Metamorphism, Deformation History and Geochemistry of Neoproterozoic Rocks of Workamba Area, Tigray Northeren Ethioipia
| dc.contributor.advisor | Alene, Mulugeta (PhD) | |
| dc.contributor.author | Mulualem, Wuletaw | |
| dc.date.accessioned | 2018-07-11T13:42:14Z | |
| dc.date.accessioned | 2023-11-09T14:10:00Z | |
| dc.date.available | 2018-07-11T13:42:14Z | |
| dc.date.available | 2023-11-09T14:10:00Z | |
| dc.date.issued | 2017-05 | |
| dc.description.abstract | The Workamba area is situated within Northern Ethiopia and covered by widely distributed metavolcano-sedimentary Neoproterozoic basement rocks which belong to the Tsaliet and Tambien Groups in the southern part of Arabian Nubian Shield (ANS). In this study the integrated petrographic, structural kinematics and geochemical analysis has been carried out to understand the metamorphism, deformation history and geochemistry of the area. The foliated and nonfoliated metabasics, metabasaltic-andesite with intercalation of tuffaceous layer, metavolcanoclastic and metabreccia rock units are characterize the Tsaliet Group whreas, metasedimentary rock units include; metalimestone, graphitic slate, phyllite and micaceous slate are represent the Tembain group. The index mineral assemblages such as chlorite, actinolite, epidote, muscovite and serisite which established from petrographic analysis indicate that the study area has been experienced low grade metamorphism (green schist facies metamorphism). Petrographic, macro and micro scale geologic structure studies show that the study area has experienced two phases of ductile deformation (D1 and D2) and later affected by third phase brittle deformation. Metamorphism-deformation relationships are recognized from mineral assemblages and micro-structural features. D1 is established by NE striking S1foliation and regional M1 metamorphic event synchronous with D1 is responsible for development of mineral assemblages such as chlorite, epidote, actinolite, muscovite/sericite, calcite, graphite and recrystallized quartz. The second phase deformation (D2) is characterized by the local development of low plunging folds, S2 cleavage and kink fold. During D2 deformation S1foliation is folded to S2 crenulation cleavage by slightly rotation and recrystallization of platy minerals i.e., micas therefore S2 cleavage can be accommodate by M2 metamorphic event synchronous with D2 deformation. The third phase deformation (D3) is related to different set of joints that cross cut the regional foliation throughout each rock units. The geochemical data plotted on different tectonic discrimination diagrams clearly reveals that metavolcanic rocks of Workamba area are characterized by typical calc-alkaline suites. The general petrological and geochemical characteristics of the Workamba metavolcanic rocks provides an important evidence to consider the area as part of the arc volcanics sequence or subduction-related arc accretion of the ANS | en_US |
| dc.identifier.uri | http://10.90.10.223:4000/handle/123456789/8117 | |
| dc.language.iso | en | en_US |
| dc.publisher | Addis Ababa Universty | en_US |
| dc.subject | Neoproterozoic Rocks | en_US |
| dc.title | Metamorphism, Deformation History and Geochemistry of Neoproterozoic Rocks of Workamba Area, Tigray Northeren Ethioipia | en_US |
| dc.type | Thesis | en_US |