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Gamma-ray spectrometry of the Araguainha impact structure, Brazil: Additional insights into element mobilization due to hydrothermal alteration
- Source :
- Anais da Academia Brasileira de Ciências, Vol 94, Iss 3 (2022)
- Publication Year :
- 2022
- Publisher :
- Academia Brasileira de Ciências, 2022.
-
Abstract
- Abstract We present the analysis of airborne and ground gamma-ray spectrometry signatures of the Araguainha impact structure, located in central Brazil, the largest impact structure in South America with ~ 40 km diameter. The airborne data are total gamma-ray counts per second collected along flight lines spaced 1 km apart. The ground gamma-ray data are concentrations of potassium, uranium, and thorium isotopes calculated from radiations measured in three individual channels. The objectives are to distinguish lithologies within the structure, which have naturally distinctive radiogenic signatures, and identify potential post-impact hydrothermal alteration zones, as indicated by high K concentrations. Based on results obtained by numerical modeling of the crater formation, we infer the locations of potential occurrences of target rocks that may have undergone hydrothermal alteration as a result of the impact. The deviations from the background potassium concentration show significant anomalous K values at the center and in the northwestern crater rim, where high concentrations of U are also observed. The numerical model shows that ideal temperature conditions for hydrothermal fluid circulation were attained right after pos-impact gravitational stabilization.
- Subjects :
- Araguainha
gamma-ray
geophysics
impact crater
Science
Subjects
Details
- Language :
- English
- ISSN :
- 16782690 and 00013765
- Volume :
- 94
- Issue :
- 3
- Database :
- Directory of Open Access Journals
- Journal :
- Anais da Academia Brasileira de Ciências
- Publication Type :
- Academic Journal
- Accession number :
- edsdoj.fa44954d90f2466d8902f5bdb4ea6585
- Document Type :
- article
- Full Text :
- https://doi.org/10.1590/0001-3765202220210182