Archean crust and metallogenic zones in the Amazonian Craton sensed by satellite gravity data

Abstract

The formation of ore deposits has been extensively studied from a shallow crust perspective. In contrast, the association of mineral systems with deep crustal structure of their host terranes remains relatively undisclosed, and there is evidence that processes throughout the lithosphere are coupled for their evolution. The current debate centers on the control of the regional deep crustal architecture in focusing and transferring fluids between geochemical reservoirs. Defining such architecture is not unequivocal, and involves combining indirect information in order to constrain its physical properties and evolution. Herein, based on evidence from satellite gravity, constrained by airborne potential field data (gravity and magnetics), we provide an example on how the lithosphere geometry controlled the location of copper and gold systems in the world-class Archean Carajás Mineral Province (Amazonian Craton, South America). Validation with information from passive seismic (wave speeds, crustal and lithospheric thickness) and geochronologic data (model, crystallization ages, and Neodymium isotope ratio determinations) portrays a significantly enlarged, poly-phase, Archean crust that exerted geometric control on the location of the mineral systems within and adjacent to the province during tectonic quiescence and switches. This new geologic scenario impacts the understanding of the Amazonian Craton. Synergy between multi-source data, as experimented here, can provide robust models efficiently and, conceivably, help to unveil similar terrains elsewhere.

Mapping the Thermal Structure of the Amazon Craton to Constrain the Tectonic Domains

“…Motta et al. (2019) suggest that CJD and BD are a single lithospheric unit with the same evolution at least up to 2.5 Ga based on Sm‐Nd models and crystallization ages. Likewise, p ‐wave velocity corroborates this theory due to the high‐velocity anomaly shared by BD and CJD.…”

“…Melting of the Archean mantle evidenced by greenstone belts influenced the rigidity of the crust, enhancing its mobility (Lourenço et al, 2016;Nebel et al, 2018). Motta et al (2019) suggest that CJD and BD are a single lithospheric unit with the same evolution at least up to 2.5 Ga based on Sm-Nd models and crystallization ages. Likewise, p-wave velocity corroborates this theory due to the high-velocity anomaly shared by BD and CJD.…”

Satellite gravity data as a tool for kimberlite exploration – insights from southern Africa

“…Posterior forward modeling of the gravity effect of the rocks contained at the topographic surface (from the ETOPO1 model 11 lead to the topography effect and its removal from the simple Bouguer anomaly led to the Complete Bouguer Anomaly map. The processing pipeline is as in the previous publications 12,13 . The resulting Complete Bouguer Anomaly map and other data were interpreted qualitatively as maps.…”

Textural analysis and emplacement conditions of well-preserved Orosirian felsic volcanic rocks of Northern Amazon Craton, Brazil

“…1A), the Amazonian Craton consists of the largest Precambrian domain in the South American Platform (Almeida et al, 1981). This terrane hosts some of the most important mineral deposits of the world (e.g., Juliani et al, 2005;Bettencourt et al, 2016;Motta et al, 2019), as well as a significant geological record of the Paleoproterozoic period. The widespread Uatumã volcano-plutonic event (1.89-1.87 Ga) covers 1.2 million km 2 of the Amazonian Craton (Fig.…”