Characterization of crustal structure by comparing reflectivity patterns of wide-angle and near vertical seismic data from the Parnaiba Basin, Brazil

Marcus Vinicius A. G. de Lima* (Corresponding Author), Randell A. Stephenson, Jose Eduardo P. Soares, Reinhardt A. Fuck, Vitto C. M. de Araujo, Flavio T. Lima, Fabio A. S. Rocha

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Recently an ambitious experiment combining deep seismic surveys from near-vertical and wide-angle acquisition methods was carried out in Brazil. The seismic lines are essentially coincident and crossed the Parnaiba Basin from west to east near latitude 5 degrees S. Here, the wide-angle reflection and refraction (WARR) and deep seismic reflection (DSR) results, which were previously interpreted independently, are compared by directly correlating WARR interfaces converted to TWTT with the major reflective horizons identified in the zero-offset image and by considering coincident reflectivity patterns displayed in both data sets. This integrated WARR and DSR analysis allowed a spatial association of the apparently acoustically featureless crust imaged in the DSR profile to the high reflectivity observed in the WARR data. Numerical tests and elastic modelling show that variations of the elastic properties of the crust, particularly as they are characterized by low Vp and Vs contrasts with a possible increase of the Vp/Vs ratio, can only weakly explain the observed reflectivity patterns but that fine-scale lithological heterogeneity within the crust is capable of replicating the observed contrasting seismic responses. The segment of the Parnaiba Basin crust that is characterized by fine-scale lithological heterogeneity lies directly above a mafic crustal underplate defined by the WARR model and was named as the Grajau domain on the basis of WARR-derived velocity model. The applied methodologies allow added value to be taken from the independent seismic data sets and provide new information about crustal structure that may have important implications for overlying intracontinental basin evolution.

Original languageEnglish
Pages (from-to)1652-1664
Number of pages13
JournalGeophysical Journal International
Volume218
Issue number3
Early online date16 May 2019
DOIs
Publication statusPublished - Sep 2019

Keywords

  • Composition and structure of the continental crust
  • South America
  • Controlled source seismology
  • Crustal imaging
  • Crustal structure
  • CRATONIC BASIN
  • REFRACTION
  • BASEMENT
  • GRAVITY
  • BENEATH

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

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