Superfície Curie Da Região Central De Goiás

Abstract

CURIE SURFACE OF THE GOIÁS CENTRAL REGION The study area is located in the central region of the State of Goiás, between 14° and 16° South and 48° and 51° West and is a part of the Tocantins Structural Province. Several geophysical surveys were performed in the region starting in the 70's, with the Brazil-Canada Geophysical Project (PGBC) when a regional aeromagnetic survey took place. Magnetic interpretation of prismatic models allows the evaluation of depths where rocks lose their magnetization, the Curie depth. A group of depths defines a Curie surface. Depth were evaluated for 13984 locations in the studied area. The Curie surface indicates shallow areas with characteristic linear pattern referred as 'Curie crests', and deep regions representing the magnetic basement for the crust. The surface was compared with geological map and Bouguer map and with the distribution of gold occurrences in the study area. Many of the Curie crests coincide with ancient structural elements containing hydrothermal mineralizations. The Pirineus Megainflection and the Niquelândia Inflection are remarkable features. Parallelism and coincidence with greenstone belts and volcano-sedimentary sequences are clear. The relation with gravity map indicates an ancient suture. Four episodes are suggested to explain the origin of Curie structures: 1) Collision episode, responsible for the geosuture formation; 2) Late erogenic extentional episode, responsible for granitoid and shear zone mineralizations; 3) Sul-Atlantian episode, related with Gondwanaland disruption, and 4) Recent episode, related to E-W regional stresses as the result of South-American plate tectonic. The relationship between gold mineralizations with Curie crests suggest that the former may be a good guide for prospecting in the region.

The tectonic evolution of the Transbrasiliano Lineament in northern Paraná Basin, Brazil, as inferred from aeromagnetic data

“…However, the deepest crustal magnetic contrast of the Bom Jardim domain is only 15 km, suggesting either crustal thinning or the presence of a highly magnetized body 15 km depth, possibly a large mafic intrusion. Blum and Pires [] produced a Curie depth map of the central region of Goiás, which offers insights for our study area. They estimated an average Curie depth of 30 km, with shallower peaks related to faults, including part of the TBL.…”

Crustal framework of the northwest Paraná Basin, Brazil: Insights from joint modeling of magnetic and gravity data

“…They interpreted this westward increase in crustal thickness as being caused by different phases and directions of subduction, based on possible overlapping crust and delamination of the lower crust, and distinct properties of the lithospheric mantle. Blum and Pires (1996) estimated an average Curie depth of 30 km in this same region, with shallow regions of the Curie isotherm related to faults, including the TBL. Regionally, the NE-SW trending zone between Amazonian and São Francisco paleoplates (Figure 1), in agreement with the main trend of TBL, is characterized by thinner lithosphere compared to adjacent terranes (Rocha et al, 2011;Azevedo et al, 2015), which may explain high intraplate seismicity along this direction (Assumpção and Sacek, 2013).…”

Precambrian tectonic inheritance control of the NE Brazilian continental margin revealed by Curie point depth estimation

“…A few investigations have been published on crust thermal properties of the South American platform, focusing on southeastern continental margins [Gomes and Hamza, 2005;Cardozo and Hamza, 2014] and cratonic regions [Blum, 1996;Hurter and Pollack, 1996;Guimarães et al, 2013;Correa et al, 2016]. A study of the thermal gradient in the onshore region of the Potiguar Basin, based on 164 stratigraphic wells, showed geothermal gradients ranging from 24 to 74 °C/km, with a mean value of 37° C/km [Souto Filho, 1984].…”