Accretionary models for the Neoproterozoic evolution of the Borborema Province: advances and open questions

Lauro Cézar Montefalco De Lira Santos,Fabricio Caxito

doi:10.1590/2317-4889202120200104

Abstract

The current knowledge on the accretionary evolution of the Borborema Province is evaluated considering recently published data and interpretations. Early to late Neoproterozoic eclogite, ophiolite, and magmatic arc remnants have been documented and point to oceanic crust consumption. Isotopic contrasts as well as geophysical anomalies across the major domain boundaries are suggestive of collisional sutures and a speculative model of terrane accretion is presented here. On the other hand, the lack of concise evidence for some of the proposed deep-seated structures as well as putative lithospheric continuity in both sides of it suggest reworking of previously continuous lithosphere through intracontinental deformation in localized sectors of the province interior. It is patent that one model does not preclude the other and available evidence so far has triggered the emergence of conciliatory proposals for the Neoporterozoic history the Borborema Province.

Highlights

The lack of consensus on how Earth dynamics have operated through time feeds warm debates in the scientific community
The Borborema Province (BP; NE Brazil), like other Neoproterozoic orogenic areas of Brazil, is part of the large system proposed by Almeida et al (1981), built-up through convergence of the São FranciscoCongo and São Luis-West African paleocontinents during the Brasiliano Orogeny
The BP corresponds to the Neoproterozoic northeastern portion of the South American Platform

Summary

INTRODUCTION

The lack of consensus on how Earth dynamics have operated through time feeds warm debates in the scientific community. Santos and Medeiros 1999, Brito Neves et al 2000), whereas intracontinental mechanisms were proposed to explain the lack of contrast between some of these domains (Neves 2003). New alternatives proposing both the acting of typical modern-style plate tectonics processes and reworking of older basement blocks in the interior of the province have emerged The goal of this contribution is to present an update of ideas mainly related to the accretionary model since the seminal work of Santos (1996) and future perspectives for the evolutionary dynamics of the BP

GEOLOGICAL SETTING

THE CASE FOR AN ACCRETIONARY MODEL

PROBLEMS AND OPEN QUESTIONS