Emplacement of the paleoproterozoic Itareru tonalite (NE Sao ˜ Francisco Craton, Brazil) during arc-continent collision revealed by magnetic fabrics

Primeiro Autor Patroni, O. A. L., Raposo, M. I. B., D'Agrella-Filho, M. S., & de Oliveira, E. P.
Autores Patroni, O. A. L., Raposo, M. I. B., D'Agrella-Filho, M. S., & de Oliveira, E. P.
Resumo

The Itareru tonalite is one of the Paleoproterozoic plutonic rock units that intruded the Serrinha block, an Archean-Paleoproterozoic crustal fragment of the S˜ ao Francisco Craton (Bahia, Brazil). It is characterized by a ca. 80 km long, NW-SE elongated leaf-shaped body, mainly comprised of tonalite-diorite to granodiorite rocks with numerous dioritic enclaves. Magnetic studies were performed on 26 sites of the Itareru pluton (including country rocks). Anisotropy of low-field magnetic susceptibility (AMS) and anisotropy of anhysteretic remanent magnetization (AARM) are coaxial, indicating that all minerals have the same orientation, partially controlled by regional strain. Rock-magnetism measurements reveal that paramagnetic–matrix minerals contributed significantly to the magnetic susceptibility and AMS while magnetite grains in the range of 2–5 μm are responsible for AARM. Magnetic fabrics in the central region of the pluton are probably primary (magmatic), which was acquired when the rocks were crystallized, reflecting magma flow linked to a magma feeder zone (magma chamber). The moderated magnetic lineation plunges in the northern part of the pluton suggest that this region was close to the feeder zone. In contrast, the southern region should be far from it, since the magnetic lineations are horizontal to sub-horizontal. The Itareru tonalite emplacement was also controlled by regional strains related to the collision of the Paleoproterozoic Rio Itapicuru greenstone Belt with the Archean basement.

Programa Geofísica
Ano de publicação 2024
Tipo de publicação Artigo publicado em revista
Nome da revista/jornal Journal of South American Earth Sciences
Localidade Publicação Internacional
Volume 134
Número 104756
DOI https://doi.org/10.1016/j.jsames.2023.104756
Palavras chave Keywords:
Magnetic fabrics
AMS
AARM
Itareru
Sao ˜ Francisco craton
Tonalite
Página web https://www.sciencedirect.com/science/article/pii/S0895981123005680?via%3Dihub