Tectonic evolution of the Proterozoic Itremo Group metasediments in central Madagascar

Fernandez, A.; Schreurs, Guido (2003). Tectonic evolution of the Proterozoic Itremo Group metasediments in central Madagascar. Geological Society Special Publications, 206(1), pp. 381-399. Geological Society 10.1144/GSL.SP.2003.206.01.18

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The major geologic units of the Itremo region in central Madagascar include: (1) upper amphibolite to granulite facies (higher grade) Precambrian rocks, mainly para- and orthogneisses, and migmatites; (2) the newly defined Itremo Nappes, a fold-and-thrust belt containing the Proterozoic Itremo Group sediments, metamorphosed at greenschist to lower amphibolite facies (lower grade) conditions: (3) Middle Neoproterozoic and Late Neoproterozoic-Cambrian intrusives. The stratigraphic succession of the Itremo Group in the eastern part of the Itremo region is, from bottom to top: quartzites, metapelites, metacarbonates and metapelites overlain by metacarbonates. During D1 the Itremo Group sediments were detached from their continental substratum, deformed into a fold-and-thrust nappe (Itremo Nappes), and transported on top of higher grade rocks that are intruded by Middle Neoproterozoic (c. 797–780 Ma) granites and gabbros. A second phase of deformation shortening (D2) affected both the Itremo Sedimentary Nappes and structurally underlying higher-grade rocksunits, and formed large-scale N-S-trending F2 folds. S1 axial plane foliations in Itremo Group sediments are truncated by Late Neoproterozoic-Cambrian granites (c. 570–540 Ma). The age of the formation of the Itremo Nappes is not well constrained: they formed in Neoproterozoic times between 780 and 570 Ma.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences

UniBE Contributor:

Schreurs, Guido

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

0305-8719

Publisher:

Geological Society

Language:

English

Submitter:

Guido Schreurs

Date Deposited:

18 Jul 2016 14:06

Last Modified:

18 Jul 2016 14:06

Publisher DOI:

10.1144/GSL.SP.2003.206.01.18

URI:

https://boris.unibe.ch/id/eprint/83593

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