Gravity and magnetic geophysical surveys for exploration of low sulphidation epithermal mining project. Marifil Complex, Chon Aike Igneous Province, Argentina
Marcos E. Bahía , Cecilia Pavón Pivetta , Leonardo Benedini , Andrés Costa , Nicolás Scivetti , Mercedes Barros , Daniel Gregori , Anderson Costa Dos Santos , José Kostadinoff , Mauro C. Geraldes
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引用次数: 0
Abstract
The Marifil Complex constitutes the early stage of the Chon Aike Igneous Province along eastern North Patagonia, Argentina. Geological, geochronological, and geochemical data indicate that this magmatism consists of two characteristic Lower Jurassic volcanic events (V0 and V1). The epithermal activity takes place in V1 as Au-Ag veins (Pavón Pivetta et al., 2024). Particularly, base metal veins are covered and masked by the important explosive volcanic activity related to the V1 volcanic stage. This makes geophysical exploration a highly recommended tool for interpreting subsurface geological features.
With this in mind, we have carried out the acquisition and processing of gravity and magnetic data that is supported with drill holes and geochronological data. A series of gravity and magnetic highs and lows were recognized, together with major lineaments. Using Euler deconvolution, the depth of the sources that generate the anomalies was calculated. The analysis of these results allowed us to construct two perpendicular gravity 2D models for the calculation of thicknesses and depth of the rhyolitic coulée. The gravity lows were associated with the major thickness of rhyolitic coulée, reaching 290 m in the drill holes, and interpreted geophysically to have a deeper root. The gravity highs were interpreted in two possible ways: a basement depth decrease and/or the absence of the rhyolitic coulée. The minimum depth estimated for the basement highs is approximately 20 m. These interpretations are consistent with outcrop, drill hole and geochronologic data, and magnetic maps. The RMSE between the calculated and the observed anomalies of the models are about 0.316 and 0.519 mGal. Due to the shape of the anomalies obtained from the gravimetric maps, the structures that generate the anomalies were considered as generated by three-dimensional bodies. For this purpose, we created a 3D model that provides interesting data about the possible location of these non-outcropping gravity lows that are located in the first 200 m depth.
These results demonstrate that the use of the gravity and magnetic method constitutes a useful, fast, economical, robust, and reliable tool for the identification of these volcanic structures.
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.