Crustal structure of the East-African Limpopo Margin, a strike-slip rifted corridor along the continental Mozambique Coastal Plain and North-Natal Valley

Date 2021
Author(s) Evain MikaelORCID1, Schnurle PhilippeORCID1, Lepretre Angélique1, 2, Verrier Fanny1, Watremez LouiseORCID3, Thompson Joseph Offei1, De-Clarens Philippe4, Aslanian DanielORCID1, Moulin MarylineORCID1
Affiliation(s) 1 : IFREMER, Geosciences Marines, REM/GM/LGS, Centre de Brest, 29280 Plouzané, France
2 : LGO, IUEM, Place Nicolas Copernic, 29280 Plouzané, France
3 : Univ. Lille, CNRS, Univ. Littoral Côte d’Opale, UMR 8187 – LOG – Laboratoire d’Océanologie et de Géosciences, F-59000 Lille, France
4 : TOTAL, R\&D, avenue Larribau, 64000 Pau, France
DOI 10.17882/80287
Publisher SEANOE
Keyword(s) wide-angle seismic, continental margin, Mozambique
Abstract

Coincident wide-angle and multi-channel seismic data acquired within the scope of the PAMELA Moz3-5 project allow to reconsider the formation mechanism of East-African margins offshore southern Mozambique. This study most specifically focuses on the sedimentary and deep crustal architecture of the Limpopo margin (LM) that fringes the eastern edge of the Mozambique’s Coastal Plain (MCP) and its offshore southern prolongation the North Natal Valley (NNV). It relies primarily on the MZ3 profile that runs obliquely from the northeastern NNV towards the Mozambique basin (MB) with additional inputs from a tectono-stratigraphy analysis of industrial onshore-offshore seismic lines and nearby or crossing velocity models from companion studies. Over its entire N-S extension the LM appears segmented in (1) a western domain that shows the progressive eastward crustal thinning and termination of the MCP/NNV continental crust and its overlying pre-Neocomien volcano-sedimentary basement; and (2) a central corridor of anomalous crust bounded to the east by the Mozambique fracture zone (MFZ) and the oceanic crust of the MB. A prominent basement high marks the boundary between these two domains. Its development was most probably controlled by a steep and deeply rooted fault, i.e. the Limpopo fault. We infer that strike-slip or slightly trans-tensional rifting occurred along the LM and was accommodated along this Limpopo fault. At depth we propose that ductile shearing was responsible for the thinning of the continental crust and an oceanward flow of lower crustal material. This process was accompanied by intense magmatism that extruded to form the volcanic basement and gave to the corridor its peculiar structure and mixed nature. The whole region remained at a relative high level during the rifting period and a shallow marine environment dominated the pre-Neocomien period during the early phase of continent-ocean interaction. It is only some times after break-up in the MB and the initiation of the MFZ that decoupling occurred between the MCP/NNV and the corridor allowing for the latter to subside and being covered by deep marine sediments. A scenario for the early evolution and formation of the LM is proposed taking into account both recent kinematic and geological constraints. It implies that no or little changes in extensional direction occurred between the intra-continental rifting and subsequent phase of continent-ocean interaction.

Licence CC-BY-NC-ND
Data
File Size Format Processing Access
p-wave velocity model of MZ3 profile in RAYINVR v.in format 20 KB TEXTE Processed data Open access
Travel times picked MZ3 OBS records in RAYINVR tx.in format 3 MB TEXTE Processed data Open access
Correspondence between seismic phases and travel time picks ids provided in the RAYINR tx.in file (4th column) for MZ3 profile 42 KB PDF Processed data Open access
Top of the page

How to cite 

Evain Mikael, Schnurle Philippe, Lepretre Angélique, Verrier Fanny, Watremez Louise, Thompson Joseph Offei, De-Clarens Philippe, Aslanian Daniel, Moulin Maryline (2021). Crustal structure of the East-African Limpopo Margin, a strike-slip rifted corridor along the continental Mozambique Coastal Plain and North-Natal Valley. SEANOE. https://doi.org/10.17882/80287