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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.)

Gravity and magnetic 3D inversion of Morro do Engenho complex, Central Brazil

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Author(s):
Dutra, Alanna C. [1] ; Marangoni, Yara R. [1]
Total Authors: 2
Affiliation:
[1] IAG USP, Dept Geophys, Inst Astron Geofis & Ciencias Atmosfer, BR-05508090 Sao Paulo - Brazil
Total Affiliations: 1
Document type: Journal article
Source: Journal of South American Earth Sciences; v. 28, n. 2, p. 193-203, AUG-SEP 2009.
Web of Science Citations: 14
Abstract

In the Goias Alkaline Province, in central Brazil, some mafic-ultramafic alkaline bodies crop out, such as Morro do Engenho Complex (ME), whereas other intrusive bodies are completely covered by Quaternary sediments, such as A2 body, and can only be defined by their magnetic and gravity responses. The bodies give rise to strong gravity and magnetic anomalies. We inverted the gravity and magnetic data to estimate 3D density and magnetic intensity contrasts. The gravity inversion reveals that ME and A2 intrusions, totally emplaced in the upper crust, have maximum depths of about 10 and 6 km, respectively. The estimated density contrast distribution indicates a NE-SW preferential direction for ME intrusive body. Since the remnant magnetization is very important in the area, we inverted the magnetic data, testing two hypotheses: only induced field and induced plus remnant magnetizations. The results of the inversion using only induced field could not explain the observed magnetic field, which was about 1000 nT larger than the calculated one. Induced plus remnant field inferred from wandering polar path fitted the observations. 3D magnetic inversions when remnant magnetization was included recover deeper and thinner bodies compared with gravity inversion. The inverted bodies have spherical shapes which are more consistent with the model of magmatic chambers instead of plug intrusions. (C) 2009 Elsevier Ltd. All rights reserved. (AU)