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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Paraguay-Araguaia Belt Conductivity Anomaly: A fundamental tectonic boundary in South American Platform imaged by electromagnetic induction surveys

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Author(s):
Bologna, M. S. [1] ; Padilha, A. L. [2] ; Padua, M. B. [2] ; Vitorello, I. [2] ; Chamalaun, F. H. [3]
Total Authors: 5
Affiliation:
[1] Univ Sao Paulo, Dept Geofis, BR-05508090 Sao Paulo - Brazil
[2] Inst Nacl Pesquisas Espaciais, Sao Paulo - Brazil
[3] Flinders Univ S Australia, Sch Chem Phys & Earth Sci, Adelaide, SA 5001 - Australia
Total Affiliations: 3
Document type: Journal article
Source: GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS; v. 15, n. 3, p. 509-515, MAR 2014.
Web of Science Citations: 7
Abstract

We discovered and mapped a 1200 km-long zone of enhanced electrical conductivity through a large array of magnetometers, over a narrow corridor parallel to the Paraguay and Araguaia belts which surround the Amazon craton. The anomaly has been further studied using magnetotelluric measurements made along a 300 km profile crossing the Paraguay belt; modeling shows the anomaly at this location as a very strong 100 km-wide upper-crust to mid-crust conductor, located under a region where surficial rocks show an increase in deformation and metamorphism within the belt. From the high conductivity of the anomalous structure, its observed geometry and surface rock exposures, the most likely interpretation of its source is graphitized biogenic material in metasediments, now deeply underthrust in a Neoproterozoic or Early Cambrian suture zone. This result strongly supports the hypothesis that the collision between the Amazon plate and the western Parana block has probably closed an ocean in the Paraguay belt region, contrary to former propositions of an ensialic evolution for this belt. Although the precise age of this ocean closure have been a matter of debate, our finding significantly constrains the tectonic setting of West Gondwana amalgamation involving the Amazon plate and its surrounding blocks. Key Points <list list-type={''}bulleted{''}> Mapping of geoelectric anomalies using a large array of magnetometers Strong conductivity anomalies in the lithosphere marginal to the Amazon craton Integration of GDS and MT data constrains the West Gondwana amalgamation (AU)

FAPESP's process: 09/50493-8 - Crustal and lithospheric mantle models under the Paraná and Chaco-Paraná basins by merging satellite gravity gradiometry, terrestrial gravimetry and geomagnetic and electromagnetic soundings
Grantee:Icaro Vitorello
Support Opportunities: Research Projects - Thematic Grants
FAPESP's process: 00/00806-5 - Probing geoelectrical structures in the upper-mantle under the shield in South-Central Brazil
Grantee:Icaro Vitorello
Support Opportunities: Research Projects - Thematic Grants