Project Details
Projekt
Crustal structure and subsidence history of the conjugate South Atlantic passive continental margins
Applicant
Dr. Bernd Schreckenberger, since 12/2008
Subject Area
Geophysics and Geodesy
Term
from 2008 to 2015
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 79398816
The South Atlantic continental margins are subjects of intensive research within the scope of DFG priority program SAMPLE. Breakup processes and formation of initial oceanic crust can be studied in a regional as well as an exemplary manner on the conjugated African and South American margins.In the proposed study, a high resolution image of the crustal structures of both continental margins alongside a tight fit plate reconstruction model especially for the earliest rifting phase are supposed to be created based on existing marine geophysical data (reflection and refraction seismic data, potential field data). Precisely conjugated segments will be focal points of the study, helping to draw conclusions regarding the processes, forces and other influences on continental breakup. The work is based on our image of the margin structures, the comparison of systematic variations along the continent-ocean-transition (segmentation) and the symmetries and asymmetries of the conjugated segments. Furthermore, the influence of mantle processes on the structure of continental margins will be investigated. In the first phase of this project, previously unpublished reflection seismic data from the southern African continental margins were newly processed and integrated with further seismic data available to us to form a structural map and overview of the margin. This research has recently been submitted for publication. The volcanic extrusives are imaged in seismic data as prominent seaward dipping reflector sequences. Volcanic and non-volcanic segments can be distinguished and several segments within the volcanic part have to be integrated into breakup models. Various phases of volcanic activity are imaged and it is likely that pre-rift inherited structures heavily influenced the distribution of volcanics. Many of the findings from the African continental margin are comparable to what has been described for the American side but they cannot simply be called symmetrical as structural differences are abundant. The detailed comparison of both margins and the conclusions drawn from these investigations are meant to be the topic of this renewal proposal. Specifically, a tight-fit chrono-spatial reconstruction of the earliest phases of the South Atlantic breakup is an important priority. Previously existing models featuring a South to North un-zipping model for the breakup seem to be confirmed but, partly due to a more global scope of the reconstructions, previous reconstruction are not fully compatible to our data so far. We expect our investigations, together with the diverse research within the SAMPLE-group, to contribute to the clarification of important questions. These are the differentiation and validation of different rift-models, identification of mechanisms for the emplacement of volcanics and the influence of mantle processes on the breakup as well as to add crucial data for the earliest phase of rifting to existing plate reconstruction models.
DFG Programme
Priority Programmes
Participating Person
Dr. Dieter Franke
Ehemaliger Antragsteller
Dr. Sönke Neben, until 12/2008 (†)
