Scholarlink

<p>This study aims to synthesize the metamorphic evolution of the Neoproterozoic rocks of southern Ethiopia by reviewing existing studies on the tectono-metamorphic evolution across the region. Two major polydeformed and polymetamorphosed lithotectonic terranes, consisting of granite gneiss and ophiolitic volcano-sedimentary sequences, form the Neoproterozoic rocks of southern Ethiopia. The granite gneiss terranes, composed of metamorphosed and deformed granitoids, high-grade ortho- and paragneiss, and ophiolitic volcano-sedimentary belts, represent dismembered ophiolitic rocks and island-arc assemblages. These regions have undergone multiple deformation phases, including folding, thrusting, and shearing, driven by the regional collision between West and East Gondwana. Ophiolitic mafic-ultramafic-sedimentary sequences and shear zones are affected by greenschist- to lower-amphibolite-facies metamorphism. Conversely, the granite gneiss complexes result from high-grade metamorphism of upper amphibolite to granulite facies, suggesting that these sequences were metamorphosed at different mid-crustal levels. The overall metamorphic history of southern Ethiopia can be summarized as M<sub>1</sub> (prograde metamorphism) and M<sub>2</sub> (retrograde metamorphism). M<sub>1</sub> describes progressive metamorphism that occurred alongside folding and thrusting deformation, or during the early phase of East African Orogeny. It spans from greenschist to upper amphibolite facies, with a local transition to granulite facies. M<sub>2</sub> represents a greenschist-facies retrograde metamorphism that took place along shear zones and lithological boundaries during the late stage of the orogeny. The juxtaposition of high-grade gneissic units with low-grade ophiolitic sequences along shear zones, marked by retrograde metamorphism, indicates significant denudation or exhumation of gneissic terranes to upper-crustal levels before shearing and retrograde metamorphism. The metamorphic evolution and P-T conditions of the Neoproterozoic rocks in southern Ethiopia reveal a clockwise P-T-t trajectory.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Metamorphism of the Neoproterozoic rocks of southern Ethiopia: a review

  • 期刊论文

  • 发表日期：

    2026年6月24日

查看全文
  • Ebassa Dugasa Leta

摘要

This study aims to synthesize the metamorphic evolution of the Neoproterozoic rocks of southern Ethiopia by reviewing existing studies on the tectono-metamorphic evolution across the region. Two major polydeformed and polymetamorphosed lithotectonic terranes, consisting of granite gneiss and ophiolitic volcano-sedimentary sequences, form the Neoproterozoic rocks of southern Ethiopia. The granite gneiss terranes, composed of metamorphosed and deformed granitoids, high-grade ortho- and paragneiss, and ophiolitic volcano-sedimentary belts, represent dismembered ophiolitic rocks and island-arc assemblages. These regions have undergone multiple deformation phases, including folding, thrusting, and shearing, driven by the regional collision between West and East Gondwana. Ophiolitic mafic-ultramafic-sedimentary sequences and shear zones are affected by greenschist- to lower-amphibolite-facies metamorphism. Conversely, the granite gneiss complexes result from high-grade metamorphism of upper amphibolite to granulite facies, suggesting that these sequences were metamorphosed at different mid-crustal levels. The overall metamorphic history of southern Ethiopia can be summarized as M1 (prograde metamorphism) and M2 (retrograde metamorphism). M1 describes progressive metamorphism that occurred alongside folding and thrusting deformation, or during the early phase of East African Orogeny. It spans from greenschist to upper amphibolite facies, with a local transition to granulite facies. M2 represents a greenschist-facies retrograde metamorphism that took place along shear zones and lithological boundaries during the late stage of the orogeny. The juxtaposition of high-grade gneissic units with low-grade ophiolitic sequences along shear zones, marked by retrograde metamorphism, indicates significant denudation or exhumation of gneissic terranes to upper-crustal levels before shearing and retrograde metamorphism. The metamorphic evolution and P-T conditions of the Neoproterozoic rocks in southern Ethiopia reveal a clockwise P-T-t trajectory.