| Full text | |
| Author(s): |
Dragone, Gabriel Negrucci
;
Ussami, Naomi
;
Gimenez, Mario Ernesto
;
Lince Klinger, Federico Gustavo
;
Moreno Chaves, Carlos Alberto
Total Authors: 5
|
| Document type: | Journal article |
| Source: | Precambrian Research; v. 291, p. 162-177, APR 2017. |
| Web of Science Citations: | 13 |
| Abstract | |
We present a new gravity map between 45 degrees-70 degrees W and 5 degrees-40 degrees S integrating open source terrestrial gravity data of Argentina with the South American Gravity Model 2004 (SAGM04), a 5 min-arc resolution gravity model. The Bouguer anomaly map reveals a 2000 km long linear gravity feature from 15 degrees S to 30 degrees S at longitude 55 degrees W, with a steep horizontal gradient separating two gravity domains. The eastern domain is the Parana basin, with NE-SW trending Bouguer anomalies of -80 mGal in average. The western domain comprises the Chaco-Parana, Chaco-Tarija and Pantanal basins, with circular positive anomalies of up to 20 mGal in amplitude. Previous seismic studies mapped a thinner crust of less than 35 km in the western domain and the present gravity models indicate a 10-20 kg/m(3) denser crust. On the other hand, the eastern domain has a thicker crust of more than 40 km. Seismic tomography models also show P- and S-wave velocity reduction in the western domain whereas high-velocity characterises the Parana basin. These geophysical data indicate that the gravity gradient marks a transition between two distinct lithospheres. The gravity gradient is associated with a tectonic feature referred to as the Western Parana suture/shear zone. Granites of 530-570 Ma ages, located parallel or over the gravity gradient, suggest a Neoproterozoic to Early Cambrian age suture/shear zone, thus approximately synchronous and parallel to the Pampean belt. Sediment corrected residual gravity map and its vertical derivative allow us to define the limits of the Rio Apa, Rio de la Plata and Rio Tebicuary cratons. Their eastern and western limits are the Western Parana suture and the Pampean belt, respectively. This study unravels Precambrian tectonic elements concealed by the Phanerozoic sedimentary basins adding new constraints for the amalgamation history of SW Gondwana. (C) 2017 Elsevier B.V. All rights reserved. (AU) | |
| FAPESP's process: | 09/18511-6 - Joint Inversion of Teleseismic Delay Times and Geoid Anomaly Data: New models for the Lower Crust and Upper Mantle of the Paraná Basin. |
| Grantee: | Carlos Alberto Moreno Chaves |
| Support Opportunities: | Scholarships in Brazil - Doctorate |
| 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: | 12/06082-6 - The Paraná-Etendeka magmatic province in Brazil: temporal and petrologic relationships between the tholeiitic and alkaline magmatism and geodynamic implications |
| Grantee: | Excelso Ruberti |
| Support Opportunities: | Research Projects - Thematic Grants |