Banca de DEFESA: LAURA MATANA KOPROSKI

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : LAURA MATANA KOPROSKI
DATE: 22/04/2022
TIME: 14:00
LOCAL: Instituto de Geociências
TITLE:

São José do Jacuípe suite: an ophiolitic fragment of suprasubduction zone? Petrogenetic implications for its placement in the Itabuna-Salvador-Curaçá Orogen

KEY WORDS:

Neoarchaean; orogenic belt; suprasubduccion zone; ophiolite.

PAGES: 56
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geologia
SPECIALTY: Geoquímica
SUMMARY:

The São José do Jacuípe suite (SJJS) corresponds to a lithostratigraphic association composed of mafic and ultramafic rocks that crops out in the northern portion of the Itabuna Salvador-Curaçá orogen (ISCO), in the north of the São Francisco craton. They are represented by small long-linear bodies of approximate NW-SE direction that extend over an area of approximately 381 km2, from the latitude of the city of São José do Jacuípe to the city of Itaberaba. Lithologically, SJJS is represented by anorthosites, leucogabbros, gabbronorites, gabbros, ferrogabbros and subordinately pyroxenites and serpentinites that were interpreted as components of an incomplete ophiolite sequence. The rocks are part of an orogenic belt that comprises tonalitic, granite, trandhjemitic and granodiorite granulites and gneisses of the Caraíba complex, and metasedimentary rocks of the Tanque Novo-Ipirá complex, which seems to be amalgamated into a folded melange. The petrographic analysis of the mafic/ultramafic rocks showed relict microstructures of igneous accumulation in the pyroxenites; inclusion relationships allowed the identification of two metamorphic phases, one probably at amphibolite facies and the other at granulite facies, in which the rocks are balanced as a phase final. Analytical results for major and trace elements indicate cogeneticity between the mafic rocks. The genetic lineage follows two trends, the tholeiitic and the calc-alkaline. In the geotectonic environment diagrams the rocks plot in the MORB and IAT fields. Incompatible trace elements signatures are similar to ophiolites generated in supra-subduction environments worldwide. New U/Pb LA-ICP-MS ages indicate igneous crystallization at 2549 ± 23 My and 2563 ± 13 My for SSJJ gabbronorites, which are consistent with the ages determined for other members of the magmatic arc that formed the ISCO.

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