New geological and single-zircon Pb evaporation data from the Central Guyana Domain, southeastern Roraima, Brazil: Tectonic implications for the central region of the Guyana Shield

Autor:	Moacir José Buenano Macambira, Marcelo Esteves Almeida, Sérgio de Castro Valente
Rok vydání:	2008
Předmět:	geography geography.geographical_feature_category Lineament Geochemistry Geology Fault (geology) Granulite Supercontinent Tectonics Shield Geomorphology Earth-Surface Processes Mylonite Zircon
Zdroj:	Journal of South American Earth Sciences. 26:318-328
ISSN:	0895-9811
DOI:	10.1016/j.jsames.2008.08.003
Popis:	Metagranitoid rocks, mylonites, leucogneisses and granulites occur in the Central Guyana Domain (CGD) near the Uatuma-Anaua Domain (UAD) boundary, southeastern Roraima (Brazil). These rocks are oriented along NE–SW and E–W trends and dip to NW and N, respectively. Single-zircon Pb evaporation results yielded 1724 ± 14 Ma and 1889 ± 3 Ma for a syn-kinematic foliated hornblende–biotite monzogranite and a granodioritic mylonite, respectively. These results point to a new tectonic event (Ita Event) in the area in addition to the 1.94–1.93 Ga (late- to post-Transamazonian) and the 1.35–0.98 Ga (K’Mudku) thermal tectonic events. This new event may be related, at least locally, with the evolution of the Columbia Supercontinent. In addition, the Ita Fault System is younger than 1.89 Ga (granodioritic mylonite age), contrasting with the Barauana high-grade lineament and 1.94 Ga polydeformed rocks, pointing to the needs of a major revision of lithostratigraphic column currently proposed for the CGD as well as the CGD and UAD boundary.
Databáze:	OpenAIRE
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