The West Congo Belt (WCB) is one of many Proterozoic orogens considered to be mobile belts adjacent to the margins of Archean cratons. This orogen underlies the western margin of the Congo craton in central Africa and...The West Congo Belt (WCB) is one of many Proterozoic orogens considered to be mobile belts adjacent to the margins of Archean cratons. This orogen underlies the western margin of the Congo craton in central Africa and outcrops from south-west Gabon to north-west Angola. In the Republic of Congo, the Mayombe Chain in south-west has preserved a geological record of Proterozoic to early Paleozoic rocks that have been investigated to understand the evolution of the West Congo Belt within the regional tectonic context. Investigation into lithostratigraphy and structural architecture of the Mayombe Chain has been done by earlier workers since the 19th century. However, the lack of consistent and diverse geochronological data induced several interpretations of its geodynamic setting. The chain was previously thought to be the result of more than two orogenic cycles, and subsequently to be the result of a single orogenic cycle. Recent petrographic, geochronological, geochemical data and paleogeographic reconstructions allow redefining the tectonic context and the main lithostratigraphic subdivisions of the Mayombe Chain. It is currently recognized that the Mayombe Chain consists of three major tectonostratigraphic domains: Western, Central and Eastern, which are prolongated by the Niari-Nyanga foreland basin. These lithounits seem to have been formed through a complex history that included: (i) Late Paleoproterozoic sedimentation, magmatism and metamorphism between 2110 and 1970 Ma related to the Eburnean tectono-thermal event;(ii) Neoproterozoic rifting magmatism and sedimentation;and (iii) Pan-African tectono-thermal event between 620 and 496 Ma leading to the amalgamation of western Gondwana. In this contribution, we review existing literature on this part of the West Congo Belt and summarize the current knowledge of its geologic setting with a focus on structure, lithostratigraphy and metamorphism. We aim to show how current research, with multidisciplinary approaches, changed the interpretation of the Mayombe with consideration to the Araçuaí-West Congo Orogenic system.展开更多
文摘The West Congo Belt (WCB) is one of many Proterozoic orogens considered to be mobile belts adjacent to the margins of Archean cratons. This orogen underlies the western margin of the Congo craton in central Africa and outcrops from south-west Gabon to north-west Angola. In the Republic of Congo, the Mayombe Chain in south-west has preserved a geological record of Proterozoic to early Paleozoic rocks that have been investigated to understand the evolution of the West Congo Belt within the regional tectonic context. Investigation into lithostratigraphy and structural architecture of the Mayombe Chain has been done by earlier workers since the 19th century. However, the lack of consistent and diverse geochronological data induced several interpretations of its geodynamic setting. The chain was previously thought to be the result of more than two orogenic cycles, and subsequently to be the result of a single orogenic cycle. Recent petrographic, geochronological, geochemical data and paleogeographic reconstructions allow redefining the tectonic context and the main lithostratigraphic subdivisions of the Mayombe Chain. It is currently recognized that the Mayombe Chain consists of three major tectonostratigraphic domains: Western, Central and Eastern, which are prolongated by the Niari-Nyanga foreland basin. These lithounits seem to have been formed through a complex history that included: (i) Late Paleoproterozoic sedimentation, magmatism and metamorphism between 2110 and 1970 Ma related to the Eburnean tectono-thermal event;(ii) Neoproterozoic rifting magmatism and sedimentation;and (iii) Pan-African tectono-thermal event between 620 and 496 Ma leading to the amalgamation of western Gondwana. In this contribution, we review existing literature on this part of the West Congo Belt and summarize the current knowledge of its geologic setting with a focus on structure, lithostratigraphy and metamorphism. We aim to show how current research, with multidisciplinary approaches, changed the interpretation of the Mayombe with consideration to the Araçuaí-West Congo Orogenic system.
