| Full text | |
| Author(s): |
Dutra, Alanna C.
;
Bologna, Mauricio S.
;
Dragone, Gabriel N.
Total Authors: 3
|
| Document type: | Journal article |
| Source: | Precambrian Research; v. 410, p. 15-pg., 2024-06-16. |
| Abstract | |
A high electrical conductivity belt near the southeastern margin of the Amazonian craton, known as ParaguayAraguaia Conductivity Anomaly (PACA), has been discovered and mapped over a distance of more than 1,000 km by a large array of magnetometer measurements. To precisely determine the location and structure of the conductive anomaly, we conducted a 200 -km -long magnetotelluric (MT) profile with typical site spacing of 8 km over the northern part of PACA and crossing the Goi <acute accent>as magmatic arc and Araguaia belt in Central Brazil. Threedimensional resistivity models derived from this data indicate that the PACA is not a single conductor but comprises at least two contiguous bodies at the upper to middle crust. The enhanced conductivity of the northern part of PACA is likely due to sulfide minerals deposited in an inter -arc or back -arc basin that were deformed and subsequently emplaced tectonically beneath the western Goi <acute accent>as magmatic arc. The PACA is truncated to the west by a prominent sub-vertical resistor, attributed to the Transbrasiliano lineament (TBL), a continental-scale structural feature interpreted here as a mylonitic shear zone developed late in the Neoproterozoic to Cambrian tectonic history involving the collision between Amazonian craton and proto-West Gondwana. We cannot confirm the prevailing view of an east-dip subduction of oceanic lithosphere from the Amazonian plate under the Goi <acute accent>as arc terranes. Instead, our results probably represent the record of an oblique continental collision. Regardless of its origin, the PACA may serve as a proxy for the paleo border of the Amazonian plate. Therefore, additional geophysical mapping, especially in areas covered by thick Phanerozoic sediments, is essential to constrain the tectonic evolution of West Gondwana. (AU) | |
| FAPESP's process: | 16/06114-6 - The Neoproterozoic Earth System and the rise of biological complexity |
| Grantee: | Ricardo Ivan Ferreira da Trindade |
| Support Opportunities: | Research Projects - Thematic Grants |
| FAPESP's process: | 18/08149-7 - Determination of the electrical resistivity structure of the crust and lithospheric mantle between the Goiás massIf and the Amazonian Craton |
| Grantee: | MAURICIO DE SOUZA BOLOGNA |
| Support Opportunities: | Research Grants - Visiting Researcher Grant - Brazil |
| FAPESP's process: | 09/54006-4 - A computer cluster for the Astronomy Department of the University of São Paulo Institute of Astronomy, Geophysics and Atmospheric Sciences and for the Cruzeiro do Sul University Astrophysics Center |
| Grantee: | Elisabete Maria de Gouveia Dal Pino |
| Support Opportunities: | Multi-user Equipment Program |