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

Autor(es)

Bologna, M. S. ^[1] ; Padilha, A. L. ^[2] ; Padua, M. B. ^[2] ; Vitorello, I. ^[2] ; Chamalaun, F. H. ^[3]

Afiliação do(s) autor(es)

^[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

• Tipo de documento: Artigo Científico
• Fonte: GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS; v. 15, n. 3, p. 509-515, MAR 2014.
• Citações Web of Science: 7

Resumo

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)

• Processo FAPESP: 09/50493-8 - Modelos da crosta e litosfera sob as bacias do Paraná e Chaco-Paraná integrando gradiometria gravimétrica por satélite, gravimetria terrestre e sondagens magnéticas e eletromagnéticas
• Beneficiário: Icaro Vitorello
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 00/00806-5 - Estruturas geoelétricas no manto superior sob o escudo no Centro-Sul do Brasil
• Beneficiário: Icaro Vitorello
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 01/02848-0 - Levantamentos magnetoteluricos na caracterizacao de estruturas geoeletricas na crosta e manto superior da regiao centro-oeste do brasil.
• Beneficiário: MAURICIO DE SOUZA BOLOGNA
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 03/10817-2 - Caracterizacao regional da bacia do parana atraves de sondagens geomagneticas profundas.
• Beneficiário: Antonio Lopes Padilha
• Modalidade de apoio: Auxílio à Pesquisa - Regular