{"title":"Seismotectonic and gravimetric analysis of the central Neuquén Basin","authors":"","doi":"10.1016/j.jsames.2024.105036","DOIUrl":null,"url":null,"abstract":"<div><p>Understanding the seismotectonics in the foreland region of orogenic belts is crucial for several reasons. Firstly, it allows us to infer stress conditions and structural controls in distant orogenic areas. Secondly, because these regions are often densely populated, it becomes essential to assess the associated risks, hazards, and vulnerabilities. In this study, we investigate intraplate seismicity in the foreland region of the Neuquén Basin in the southern Central Andes. Our data were obtained from a local broadband seismic network and high-resolution gravimetric enhancement methods. We analysed three distinct sets of earthquakes associated with major subsurface structural features. We found that seismic events near the Añelo locality may be linked to anthropogenic causes, underscoring the importance of identifying active structures and understanding regional tectonics. The seismicity is mostly aligned with Mesozoic transfer zones, as well as a large laccolithic magmatic intrusion. Focal mechanisms and enhanced gravimetric methods further elucidate previously unidentified structural features related to seismicity and gravity gradients. Reactivation directions coincide with reported Andean E-W maximum stress orientations. To the south of Añelo, seismicity and gravity gradient patterns suggest lineaments within the Huincul System. Notably, NE-SW trending lineaments between 71<span><math><msup><mrow></mrow><mrow><mo>∘</mo></mrow></msup></math></span>W and 70<span><math><msup><mrow></mrow><mrow><mo>∘</mo></mrow></msup></math></span>W align with seismicity possibly associated with the Agrio fold and thrust belt, and the projection of the Valdivia Fracture Zone. At 70<span><math><msup><mrow></mrow><mrow><mo>∘</mo></mrow></msup></math></span>W, E-W trending lineaments correspond to seismic activity near the Chihuidos anticline and Cortaderas lineament. At 69<span><math><msup><mrow></mrow><mrow><mo>∘</mo></mrow></msup></math></span>W, a shorter NE-SW lineament coincides with clustered seismicity, the Añelo anticline, and an eastward shift of the deformation front. Lastly, ESE-WNW trending lineaments at 68<span><math><msup><mrow></mrow><mrow><mo>∘</mo></mrow></msup></math></span>W indicate structural rotations consistent with the complex Mesozoic Huincul System framework. From these results, we propose that the Huincul System exerts strong control over the structural character and seismotectonics of the central foreland region of the Neuquén Basin. This comprehensive analysis underscores the utility of integrating diverse geophysical methods for understanding intraplate seismicity and structural dynamics in foreland basin settings.</p></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":null,"pages":null},"PeriodicalIF":1.7000,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of South American Earth Sciences","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S089598112400258X","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Understanding the seismotectonics in the foreland region of orogenic belts is crucial for several reasons. Firstly, it allows us to infer stress conditions and structural controls in distant orogenic areas. Secondly, because these regions are often densely populated, it becomes essential to assess the associated risks, hazards, and vulnerabilities. In this study, we investigate intraplate seismicity in the foreland region of the Neuquén Basin in the southern Central Andes. Our data were obtained from a local broadband seismic network and high-resolution gravimetric enhancement methods. We analysed three distinct sets of earthquakes associated with major subsurface structural features. We found that seismic events near the Añelo locality may be linked to anthropogenic causes, underscoring the importance of identifying active structures and understanding regional tectonics. The seismicity is mostly aligned with Mesozoic transfer zones, as well as a large laccolithic magmatic intrusion. Focal mechanisms and enhanced gravimetric methods further elucidate previously unidentified structural features related to seismicity and gravity gradients. Reactivation directions coincide with reported Andean E-W maximum stress orientations. To the south of Añelo, seismicity and gravity gradient patterns suggest lineaments within the Huincul System. Notably, NE-SW trending lineaments between 71W and 70W align with seismicity possibly associated with the Agrio fold and thrust belt, and the projection of the Valdivia Fracture Zone. At 70W, E-W trending lineaments correspond to seismic activity near the Chihuidos anticline and Cortaderas lineament. At 69W, a shorter NE-SW lineament coincides with clustered seismicity, the Añelo anticline, and an eastward shift of the deformation front. Lastly, ESE-WNW trending lineaments at 68W indicate structural rotations consistent with the complex Mesozoic Huincul System framework. From these results, we propose that the Huincul System exerts strong control over the structural character and seismotectonics of the central foreland region of the Neuquén Basin. This comprehensive analysis underscores the utility of integrating diverse geophysical methods for understanding intraplate seismicity and structural dynamics in foreland basin settings.
期刊介绍:
Papers must have a regional appeal and should present work of more than local significance. Research papers dealing with the regional geology of South American cratons and mobile belts, within the following research fields:
-Economic geology, metallogenesis and hydrocarbon genesis and reservoirs.
-Geophysics, geochemistry, volcanology, igneous and metamorphic petrology.
-Tectonics, neo- and seismotectonics and geodynamic modeling.
-Geomorphology, geological hazards, environmental geology, climate change in America and Antarctica, and soil research.
-Stratigraphy, sedimentology, structure and basin evolution.
-Paleontology, paleoecology, paleoclimatology and Quaternary geology.
New developments in already established regional projects and new initiatives dealing with the geology of the continent will be summarized and presented on a regular basis. Short notes, discussions, book reviews and conference and workshop reports will also be included when relevant.