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ORIGINAL RESEARCH article

Front. Earth Sci.
Sec. Petrology
Volume 12 - 2024 | doi: 10.3389/feart.2024.1497913

Magma Evolution During the Post-Rift Phase of the Santos Basin, Brazil: Petrogenesis and Geochemistry of ~126-121 Ma Basalts and Diabases

Provisionally accepted
Wenyuan He Wenyuan He 1Hongping Wang Hongping Wang 2Jinglin Su Jinglin Su 3Wangquan Wang Wangquan Wang 1Junfeng Zhao Junfeng Zhao 4Guoping Zuo Guoping Zuo 2Tongkui Wang Tongkui Wang 4Liu Yang Liu Yang 2Kangxu Ren Kangxu Ren 4Chaofeng Wang Chaofeng Wang 2Jian Zhao Jian Zhao 4Yuan Guo Yuan Guo 4Yonggang Zhang Yonggang Zhang 4Jing Sun Jing Sun 3*
  • 1 China National Oil and Gas Exploration and Development Corporation, Beijing, China
  • 2 PetroChina Hangzhou Research Institute of Geology, Hangzhou, Jiangsu Province, China
  • 3 College of Geosciences, China University of Petroleum, Beijing, China
  • 4 CNPC Brasil Petroleo e Gas Ltda, Rio de Janeiro, Brazil

The final, formatted version of the article will be published soon.

    The Santos Basin, a passive continental margin basin recognized for its vast deep-sea hydrocarbon potential, poses unique geological issues due to the large amount of igneous rocks revealed by drilling data. This research explores into the petrogenesis and geochemistry of ~126-121 Ma basalts and diabases to understand the magmatic evolution during the post-rift phase. The geochronological evidence indicates the derivation of these rocks from the spinel and garnet lherzolite facies, denoted by increased La/Sm ratios that suggest a 1%-5% degree of partial melting.These findings correspond with the characteristics of continental rift basalts. The geochemical analysis hints that the older basalts and diabases were likely derived from the asthenospheric mantle, whereas the younger ones display a geochemical mix indicative of contributions from both the deeper asthenosphere and the subcontinental lithospheric mantle (SCLM), or possibly from crustal contamination. A proposed hypothetical model indicating that the deepening of the basin into the asthenosphere, in conjunction with the thinning and stretching of the lithosphere, could have been instrumental in the magmatic events recorded in the region.

    Keywords: Santos basin, Pre-salt, Continental rift basalts, Sr-Nd isotopes, Ar-Ar dating

    Received: 18 Sep 2024; Accepted: 30 Oct 2024.

    Copyright: © 2024 He, Wang, Su, Wang, Zhao, Zuo, Wang, Yang, Ren, Wang, Zhao, Guo, Zhang and Sun. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Jing Sun, College of Geosciences, China University of Petroleum, Beijing, China

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.