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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

The Neoproterozoic southern passive margin of the Sao Francisco craton: Insights on the pre-amalgamation of West Gondwana from U-Pb and Hf-Nd isotopes

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Westin, Alice [1] ; Campos Neto, Mario C. [1] ; Cawood, Peter A. [2] ; Hawkesworth, Chris J. [3] ; Dhuime, Bruno [3, 4] ; Delavault, Helene [3, 5]
Total Authors: 6
[1] Univ Sao Paulo, Inst Geociencias, Rua Lago 562, Cidade Univ, Sao Paulo, SP - Brazil
[2] Monash Univ, Sch Earth Atmosphere & Environm, Melbourne, Vic 3800 - Australia
[3] Univ Bristol, Sch Earth Sci, Wills Mem Bldg, Queens Rd, Bristol BS8 1RJ, Avon - England
[4] Univ Montpellier, Geosci Montpellier, UMR5243, CNRS, F-34095 Montpellier 05 - France
[5] Thermo Fisher Sci, 16 Ave Quebec, BP 30210, F-91941 Villebon Courtaboeuf - France
Total Affiliations: 5
Document type: Journal article
Source: Precambrian Research; v. 320, p. 454-471, JAN 2019.
Web of Science Citations: 1

Sedimentary basins are, in many cases, the only preserved record of the geological processes active through geological time. These deposits preserve age, isotopic and geochemical signatures of the source rocks, providing insights into tectonic setting. In this context, we investigate the lithostratigraphy, provenance and tectonic environment of the Carrancas Group, a meta-sedimentary sequence characterised by a basal psammitic unit (Lower Unit) passing up into interbedded psammo-pelites (Intermediate Unit), which are overlain by a further psammitic unit (Upper Unit). This succession, along with the Canastra, Paranoa and Vazante groups (Brasilia orogen), comprises a mature passive margin developed at the western-southern margin of the Sao Francisco craton during the Neoproterozoic. Detrital zircon U-Pb ages and Nd-Hf isotope data enable revised stratigraphic correlations across the basin, highlighting variations in the source of detritus. Deposition began after 0.92 Ga, with the sedimentation of the Lower Unit, with input of juvenile similar to 2.1 Ga detritus (epsilon Nd-t = -0.1 to +3.2) derived from the Sao Francisco craton. A marine transgression characterises the transition to the Intermediate Unit, which gradually covered over juvenile similar to 2.1 Ga terrains and rendered them unavailable as possible source rocks for detrital zircons. Evolved Archaean-Palaeoproterozoic basement rocks, the Espinhaco Supergroup and evolved Neoproterozoic granitoids, all belonging to the Sao Francisco craton, acted as sources for the Intermediate and Upper units (U-Pb = 2.7 Ga to 0.9 Ga; epsilon Nd-t = 10.4 to +7.1). The Goias massif might also have acted as a source, providing juvenile Mesoproterozoic detritus. The sediments of the Upper Unit register a significant shift in source, with incoming of juvenile Mesoproterozoic and crustal 1.9 1.7 Ga detritus. This change in the ages of the detrital material may be related to exhumation of the Espinhaco Supergroup during the evolution of the passive continental margin basin. The whole-rock Nd Tom model ages become progressively younger from the base to the top of the sequence (Nd T-DM = 2.6-1.8 Ga). The collisional events between Amazonian and Sao Francisco cratons and the Paranapanema block set the minimum age of deposition along this passive continental margin at around 0.67 Ga. (AU)

FAPESP's process: 13/19095-1 - Processing and interpretation of U-Pb and Lu-Hf data of zircon crystals from metasedimentary and metaigneous rocks, advised by Prof. Dr. Chris Hawkesworth at the university of st. Andrews, Scotland
Grantee:Alice Westin Teixeira
Support type: Scholarships abroad - Research Internship - Doctorate
FAPESP's process: 13/13530-8 - The orogenic margins of the Paranapanema and São Francisco blocks: from Rodinia to Gondwana
Grantee:Mario da Costa Campos Neto
Support type: Regular Research Grants
FAPESP's process: 11/13311-9 - The Carrancas Nappe System in the southern margin of the Brasilia Orogen: sedimentary provenance and tectonic setting.
Grantee:Alice Westin Teixeira
Support type: Scholarships in Brazil - Doctorate
FAPESP's process: 16/06952-1 - Thermochronology applied to geotectonic modeling: the case of the Southern Brasília orogen, Brazil
Grantee:Alice Westin Teixeira
Support type: Scholarships in Brazil - Post-Doctorate