Paleoproterozoic evolution of the Guiana Shield in Suriname: A revised model

Abstract

The Proterozoic basement of Suriname consists of a greenstone-tonalite-trondhjemite-granodiorite belt in the northeast of the country, two highgrade belts in the northwest and southwest, respectively, and a large granitoid-felsic volcanic terrain in the central part of the country, punctuated by numerous gabbroic intrusions. The basement is overlain by the subhorizontal Proterozoic Roraima sandstone formation and transected by two Proterozoic and one Jurassic dolerite dyke swarms. Late Proterozoic mylonitisation affected large parts of the basement. Almost 50 new U-Pb and Pb-Pb zircon ages and geochemical data have been obtained in Suriname, and much new data are also available from the neighbouring countries. This has led to a considerable revision of the geological evolution of the basement. The main orogenic event is the Trans-Amazonian Orogeny, resulting from southwards subduction and later collision between the Guiana Shield and the West African Craton. The first phase, between 2.18 and 2.09 Ga, shows ocean floor magmatism, volcanic arc development, sedimentation, metamorphism, anatexis and plutonism in the Marowijne Greenstone Belt and the adjacent older granites and gneisses. The second phase encompasses the evolution of the Bakhuis Granulite Belt and Coeroeni Gneiss Belt through rift-type basin formation, volcanism, sedimentation and, between 2.07 and 2.05 Ga, high-grade metamorphism. The third phase, between 1.99 and 1.95 Ga, is characterised by renewed high-grade metamorphism in the Bakhuis and Coeroeni belts along an anticlockwise cooling path, and ignimbritic volcanism and extensive and varied intrusive magmatism in the western half of the country. An alternative scenario is also discussed, implying an origin of the Coeroeni Gneiss Belt as an active continental margin, recording northwards subduction and finally collision between a magmatic arc in the south and an older northern continent. The Grenvillian collision between Laurentia and Amazonia around 1.2-1.0 Ga caused widespread mylonitisation and mica age resetting in the basement.

Gold, iron and manganese in central Amapá, Brazil

“…The laterally extensive area of occurrence of these sediments, together with the abundance of carbonates and Kroonenberg et al (2016) for the first phase of the Transamazonian Orogeny in Suriname, expressed in the Marowijne Greenstone Belt by ocean floor magmatism, volcanic arc development, sedimentation and metamorphism, accompanied by some anatexis and plutonism, a sequence of events that agrees with what is seen at Central Amapá.…”

Tectonics-mineralisation relationships within weak continental lithospheres: a new structural framework for Precambrian cratons

“…Detailed kinematic analysis of deformation features along main deformation zones often reveal complex kinematic histories with different successive structure development, locally puzzling and apparently incompatible with a simple progressive deformation history (e.g., Chown et al, 1992;Daigneault et al, 2002;Annesley et al, 2005;Lompo, 2010;Daoust, 2016;Kroonenberg et al, 2016).…”

Eburnean deformation pattern of Burkina Faso and the tectonic significance of shear zones in the West African craton

“…Furthermore, the Brobo shear zone, which is cut by the B-T mega shear (Figs. 8 and 9), could not extend southward into the Pisco-Jurua shear zone and its flanking granulite belt that form the latest (< 2.05 Ga) structure cutting the entire Guiana shield (Delor et al, 2003a;Kroonenberg et al, 2016).…”