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The evolution of the East African Orogen in central Madagascar and its Phanerozoic exhumation

English title The evolution of the East African Orogen in central Madagascar and its Phanerozoic exhumation
Applicant Schreurs Guido
Number 105453
Funding scheme Project funding (Div. I-III)
Research institution Institut für Geologie Universität Bern
Institution of higher education University of Berne - BE
Main discipline Geology
Start/End 01.12.2004 - 30.11.2007
Approved amount 280'863.00
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All Disciplines (2)

Discipline
Geology
Geochronology

Keywords (12)

MADAGASCAR; EAST AFRICAN OROGENY; GONDWANA; PRECAMBRIAN; PHANAREZOIC; EXHUMATION; Geology; Volcanics; Tectonics; Geochronology; Remote sensing; North-South collaboration

Lay Summary (English)

Lead
Lay summary
The project investigates the formation and exhumation of the East AfricanOrogen in Madagascar. The East African Orogen is a c. 6000 km longorogenic belt that formed between c. 800-500 million years ago as a resultof plate-tectonic movements that first resulted in the closure of a majoroceanic basin and then in collision of continental plates releading to theformation of a supercontinent called Gondwana. As a result of break-up ofGondwana starting about 300 Ma ago, fragments of the East African Orogenare nowadays dispersed in eastern Africa, Antarctica, India, Sri Lanka andMadagascar.The aims of the project are to better understand the timing and nature ofthe East African Orogen in central and southern Madagascar during the timeperiod 800-500 Ma and to improve our understanding of the exhumationhistory of the island of Madagascar during the last 500 Ma.In order to achieve these aims we apply a multi-disciplinary approachinvolving field studies, remote sensing analysis (using satellite images),and absolute age dating techniques. Age dating of minerals such asmonazite might help in relating ages to tectonic events and thus betterconstrain the evolution of the East African Orogen in Madagascar. Fieldstudies and absolute age dating techniques might also tell us about howand when deep-seated crustal rocks reached the surface from depths ofabout 15 to 30 km during the last 500 Ma (i.e. their exhumation history).Break-up of Gondwana since about 300 Ma resulted not only in the formationof major sedimentary basins along the western part of the island, but alsoin numerous fault systems in the old (>500 Ma) basement rocks of theisland of Madagascar. The age and significance of the basement faults incentral and southern Madagascar and their role in the exhumation ofbasement rocks will also be studied.Although the island of Madagascar is a micro-continental plate surroundedby oceanic crust, it is affected by a large number of earthquakes (>20events per year with magnitude > 4.0). The highest seismic activity occursin central Madagascar where volcanic rocks (whose age varies between about30 million years and subrecent, i.e. probably around 40000 years ago) areoften associated with brittle faults (representing fossil earthquakes). Wewill also investigate the volcanics and faults in central Madagascar inorder to determine their geodynamic significance. A by-product of ourresearch will be the production of easily readable maps and terrain modelsof this touristically attractive area that will be forwarded to localauthorities for tourism promotion.A thorough knowledge of the formation and exhumation of the East AfricanOrogen is economically relevant for Madagascar in that it will provide abetter understanding of the genesis and distribution of ore deposits, andmight help in providing a scientific basis for the establishment of hazardmitigation projects.The project is carried out in close collaboration with staff and studentsof the Department of Earth Sciences of the University of Antananarivo(Madagascar).
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Associated projects

Number Title Start Funding scheme
118023 The evolution of the East African Orogen in Madagascar and its continuation into southern India 01.12.2007 Project funding (Div. I-III)
65306 Tectono-metamorphic evolution of the East African Orogen in central-southern Madagascar and in eastern Africa 01.01.2002 Project funding (Div. I-III)

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