东北非地层区划及其地层格架与对比

    Stratigraphic divisions and their stratigraphic framework and correlation in Northeast Africa

    • 摘要: 东非造山带作为全球出露较完整的前寒武系造山带之一, 蕴藏了丰富的矿产资源。在查阅苏丹、厄立特里亚、埃塞俄比亚基础地质资料的基础上, 将研究区划分为撒哈拉、东非和东冈瓦纳3个地层大区, 进一步划分出Nukheila、Zalingei、Bayuda、Muglad-Kosti、努比亚、莫桑比克、East Ogaden和West Ogaden 8个地层区。其中, 努比亚地层区和莫桑比克地层区划分出Cabgaba地体、Gebeit地体、Haya地体、Barka地体、Hagar地体、Adobha Abiy地体、Nacfa地体、White Nile裂陷盆地、Butana基底、Ingessana-Gambela基底、Dodola-Moyale基底、Bule Nile-Atbara裂陷盆地和Main Ethiopia裂陷盆地13个地层分区。在此基础上, 对各地层区或分区中岩石地层单元进行了梳理, 结合前人同位素年代地层学和生物地层学的研究成果进行对比分析, 重新厘定上述各地层区划内岩石地层格架。通过对各地层区划内物质组成、构造特征及沉积环境的对比分析, 总结了沉积地层对地质事件的响应、探讨了研究区中生代古地貌特征, 并分析了研究区的找矿潜力区。

       

      Abstract: The East African orogenic belt, one of the most well-exposed Precambrian orogenic belts in the world, is rich of mineral resources. Based on study of a large number of literature about Sudan, Eritrea and Ethiopia, the study area is divided into SaharaStratigraphic Superregion, East Africa Stratigraphic Superregion and East Gonwana Stratigraphic Superregion, which include Nukheila stratigraphic region, Zalingei stratigraphic region, Bayuda stratigraphic region, Muglad-Kosti stratigraphic region, Nubian stratigraphic region, Mozambique stratigraphic region. Two of the eight stratigraphic regions are furtherly classified into thirteen stratigraphic divisions, such as Cabgaba terrane, Gebeit terrane, Haya terrane, Barka terrane, Hagar terrane, Adobha Abiy terrane, Nacfa terrane, White Nile rift basin, Butana base, Ingessana-Gambela base, Dodola-Moyale base, Bule Nile-Atbara rift basin and Main Ethiopia rift basin. Then, the lithostratigraphic units in each stratigraphic region or stratigraphic division were sorted out, and stratigraphic framework was stablished with the predecessors' results about isotopic chronostratigraphy and biostratigraphy. Based on comparison and analysis of the material composition, structural characteristics and sedimentary environment of the stratigraphic divisions, we summarize the sediment responsibility to geological events, discuss about the paleo-geomorphic in study area during the Mesozoic, and analyze the areas with prospecting potential.

       

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