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P-T evolution of metasedimentary rocks of the Santa Filomena Complex, Riacho do Pontal Orogen, Borborema Province (NE Brazil): Geothermobarometry and metamorphic modelling
- Source :
- Scopus, Repositório Institucional da UNESP, Universidade Estadual Paulista (UNESP), instacron:UNESP
- Publication Year :
- 2018
-
Abstract
- Made available in DSpace on 2018-12-11T17:17:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-03-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) We present in this paper petrologic data and discuss the pressure-temperature (P-T) metamorphic history of the neoproterozoic metasedimentary rocks of the Santa Filomena Complex, Riacho do Pontal Orogen, which is inserted in the southern portion of the Borborema Province (Northeast Brazil). Therefore, the data provide constraints on metamorphic evolution during Neoproterozoic Brasiliano Orogeny in Northeast Brazil. The rocks studied are aluminous schists and paragneisses. Silver-gray and red pelitic schists are intensely deformed, biotite-muscovite rich, contain centimeter-sized garnet, staurolite and kyanite porphyroblasts, and subordinately plagioclase and quartz. Paragneisses are from light gray to dark gray colored, medium to coarse-grained and display a well-spaced foliated matrix of biotite, and kyanite and garnet porphyroblasts. Locally, the schists and paragneisses are migmatized. Pressure-temperature modelling based on thermobarometric calculations indicate that metamorphism reached 643 °C with pressures estimated in 12 kbar. Pre-peak and post-peak metamorphic conditions are constrained by mineralogical and textural relationships: garnet inclusion-rich and inclusion-free (possible of higher T) are documented and the inclusion-rich core probably indicates a Sn-1 foliation that was transposed by Sn. The pre-peak stage most probably occurred close to 500 °C and 8 kbar, in upper greenschist to lower amphibolite facies metamorphism along kyanite stability field. We also propose that post-peak stage was associated with isothermal decompression along a possible path of tectonic exhumation in conditions of 600 °C and 7 kbar. To further evaluate the equilibrium condition, pressure-temperature pseudosections were calculated for the metasedimentary rocks. Thus, the estimated metamorphic peak took place in the upper amphibolite facies. A suggested clockwise pressure-temperature path is compatible with the regional tectonic setting of continent-continent collision which occurred in the Late Neoproterozoic of Borborema Province, during the Brasiliano Orogeny. Department of Geology and Natural Resources Institute of Geosciences University of Campinas, P.O. Box 6152 Institute of Engineering and Geoscience Federal University of Western Pará (UFOPA) Department of Petrology and Metallogeny Institute of Geoscience and Exact Science São Paulo State University (UNESP) Department of Petrology and Metallogeny Institute of Geoscience and Exact Science São Paulo State University (UNESP) FAPESP: 2014/03275-3
- Subjects :
- Brasiliano orogeny
010504 meteorology & atmospheric sciences
Greenschist
Geothermobarometry
Metamorphic rock
Schist
Geochemistry
Metamorphism
Geology
010502 geochemistry & geophysics
01 natural sciences
Kyanite
Upper amphibolite facies
Santa filomena complex
visual_art
Staurolite
visual_art.visual_art_medium
Metamorphic facies
0105 earth and related environmental sciences
Earth-Surface Processes
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- Scopus, Repositório Institucional da UNESP, Universidade Estadual Paulista (UNESP), instacron:UNESP
- Accession number :
- edsair.doi.dedup.....505ffa6cb254f35ceeb5a687f3a24117