Segmentation and volcano-tectonic characteristics along the SW African continental margin, South Atlantic, as derived from multichannel seismic and potential field data

Journal article
(Original article)


Publication Details

Author(s): Koopmann H, Franke D, Schreckenberger B, Schulz H, Hartwig A, Stollhofen H, Di Primio R
Journal: Marine and Petroleum Geology
Publisher: Elsevier
Publication year: 2013
Volume: 50
Pages range: 22-39
ISSN: 0264-8172
Language: English


Abstract


Regional seismic reflection and potential field data document the South Atlantic’s break-up history,

between 39S and 19S, from the Early Cretaceous onwards. Previous maps of distribution of volcanics

along the margin showed volcanics along the whole African margin based on extrapolation of data. Based

on previously unpublished marine geophysical data, we found the southernmost 460 km long margin

segment to be lacking huge volumes of break-up related volcanic effusives. Northwards, break-up was

accompanied by the emplacement of huge volumes of volcanic material, prominently featured in seismic

sections as huge wedge-shaped seaward dipping reflectors (SDRs). Detailed mapping of offsets (left- and

right-stepping) and variations in structural character of the volcanics reveal the segmentation along and

the break-up history of the margin. Several superimposed SDR sequences, suggesting episodicity of

volcanic emplacement (divided by periods of erosion and sedimentation), are distinct along southerly

lines, losing prominence northwards.

A main outcome of our study is that this passive margin is not continuously of the volcanic type and

that the change from a non-volcanic to a volcanic margin occurs abruptly.

We define four distinct First-order Segments along the 2400 km section of the southwestern African

margin covered by our seismic data. From south to north these First-order Segments are: Magma-poor

Segment I; Segment II with enormous SDRs volumes; decreasing SDRs volumes in Segment III; Segment

IV again with enormous volcanic output, likely influenced by Walvis Ridge volcanism.

Most important is that there is no systematic increase in the volumes of the effusives towards the

Tristan da Cunha hot-spot. Rather there is an alternating pattern in the SDRs’ volumes and widths.

The boundary between the volcanic and magma-poor margin segments in the southernmost study

area is sharp (10s of km), which we propose is reflected in magnetic anomaly data as well. We suggest

that this variability along the margin is mainly due to a change in stretching/rifting character from

oblique during the early stages of breakup to conventional seafloor spreading from Chron M4 (c. 130 Ma)

onwards.



FAU Authors / FAU Editors

Schulz, Henning
Geozentrum Nordbayern
Stollhofen, Harald Prof. Dr.
Lehrstuhl für Geologie (Exogene Dynamik)


External institutions
Bundesanstalt für Geowissenschaften und Rohstoffe (BGR)
Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum (GFZ)


How to cite

APA:
Koopmann, H., Franke, D., Schreckenberger, B., Schulz, H., Hartwig, A., Stollhofen, H., & Di Primio, R. (2013). Segmentation and volcano-tectonic characteristics along the SW African continental margin, South Atlantic, as derived from multichannel seismic and potential field data. Marine and Petroleum Geology, 50, 22-39. https://dx.doi.org/10.1016/j.marpetgeo.2013.10.016

MLA:
Koopmann, Hannes, et al. "Segmentation and volcano-tectonic characteristics along the SW African continental margin, South Atlantic, as derived from multichannel seismic and potential field data." Marine and Petroleum Geology 50 (2013): 22-39.

BibTeX: 

Last updated on 2018-09-08 at 16:38