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Evolution of a micro-continent during continental break-up; re-evaluating the Falklands Plateau

Dr Douglas Paton (SEE), Dr Estelle Mortimer (SEE), Prof Dave Hodgson (SEE), Dr Dave McCarthy (BGS)

Project partner(s): British Geological Survey (CASE)

Contact email: d.a.paton@leeds.ac.uk

The Falkland Plateau Basin forms a critical element of Gondwana reconstructions because it sits at the juncture of Southern Africa, South America and East Antarctica. Although the basin has received significant interest in terms of hydrocarbon exploration over recent years, few studies have attempted to place the area within the context of a fully constrained tectonic framework. Not only does this limit our understanding of the true fit of the southern continents (Southern Africa, South America and East Antarctica), it also means that the tectonic evolution of the basin remains enigmatic. Furthermore, these limitations increase uncertainty for future hydrocarbon exploration in the region.

Figure 1 - Current restoration of the Falklands during Gondwana break-up (Macdonald et al, 2003).

This project will address both blue-skies and applied questions, and will further the understanding of how fundamental crustal processes interact during continental separation.

The region forms an intriguing margin, as it represents the complex interplay of lithospheric heterogeneity and extension, intra-continental strike-slip, micro-continental block rotation, break-up volcanism and oceanic basin formation

From the perspective of hydrocarbon prospectivity the key questions remaining regard provenance and timing of clastic sedimentary input, evolution of palaeo-geography and predictions of source rock distribution, timing and extent of volcanism, heat flow variation as a function of both volcanic addition and lithospheric stretching, and predicted Gross Depositional Environment mapping. 

Using seismic reflection data, gravity and magnetic data, and plate restoration techniques the central aim of this project is to establish the tectonic configuration and evolution of the Eastern Falklands Plateau area. This will be achieved through an integrated and iterative approach to basin analysis (e.g Paton et al., 2006). Although the focus of the project is the Falklands area it is important to understand its position in the context of the wider tectonic setting.

Figure 2 - Restored and reconstructed reflection profile of the Falklands Plateau representing the palaeo-geometry in the Early Aptian.

Figure 2 is an example of a seismic profile through the Falklands restored to a syn-break up geometry. This illustrates the presence of significant basement structures, but also the significant influence of the Aghulas Falklands Fracture Zone (a 1200km long transfer fault) and how this would have controlled sediment dispersal.

Objectives:

To ensure a successful context for the project it will utilise the existing research and data available to the Basin Structure Group at the University of Leeds, as well as the expertise available at the British Geological Survey. The Leeds group has worked in the onshore and offshore structure of the Falklands (Macdonald et al., 2003), but also extensively in the conjugate margin of southern Africa (Paton et al., 2006) and the Durban basin which is the along trend continuity of the Maurice Ewing Bank and Eastern Falklands Plateau (Passandra, 2016). The British Geological Survey has worked extensively with government and industry on all of the sedimentary basins surrounding the Falklands since the early nineties, and has developed an in depth understanding of the petroleum basin evolution of the area.

In particular, according to your particular research interests, the studentship could involve

1.    Evaluation of existing plate models and reconstructions including developing an understanding of petroleum systems of the region

2.    Seismic interpretation of the East Falklands Plateau and Maurice Ewing Bank to define a structural framework model.

3.    Gravity and magnetic modelling to constrain the seismic interpretation.

4.    Correlation of structural framework into adjacent conjugate areas.

5.    Analysis of the plate reconstructions and calibration from the structural framework.

6.    Evaluation of palaeo-geography in a restored context to understanding sediment generation and dispersal.

Potential for high impact outcome

Transform faults and their evolution into transfer faults form a critical element of plate tectonics during both continental break-up and ocean basin formation. In many such examples they are associated with the development of micro-continental blocks that may undergo horizontal rotation. The project provides a unique opportunity to study the evolution of these blocks and place it into the context of a well constrained plate reconstruction. Not only will the study provide new insights into the processes involved during continental break up it will also consider the rapid changes in paleogeography that are associated with the tectonic evolution. We therefore anticipate that the project will result in at least paper being submitted to a high impact journal and that the study will be included within an industry impact case study.

Training

The student for this project will be given the opportunity to develop additional skills training through both the generic skills training provided by the University of Leeds, but also through a range of available modules on the MSc Structural Geology with Geophysics, including Structural Models, Structural Restorations, Geophysical Methods, fieldtrips, Geomechanics, and Basin Dynamics. Specific training will be provided in a wide range of appropriate software, including Petrel (seismic interpretation and fault analysis), Move (structural restorations), Geosoft (gravity and magnetics), Petromod (petroleum systems modelling).

In addition to the range of training possibilities at Leeds, the student will have access to a number of professional courses provided by BGS as they arise. Through the combined support of UofL Basin Structure Group and the BGS the student will have unrivalled access to industry relevant research expertise. This will allow the student to progress to either a research or industry facing career after successful completion of the project.

Student profile:

The student should have a strong Geoscience background, and preferably have undertaken an MSc in Geosciences or related topic. Experience of seismic reflection interpretation, gravity modelling and structural restorations would be beneficial.

CASE Partner

The British Geological Survey is a world-leading geological survey that provides expert services and impartial advice in all areas of geosciences. Their Petroleum Geoscience team has worked with the Falkland Islands Government since 1992 and provides advice on the exploration setting and potential of all of the offshore basins.

References

  • Carsandas, N, 2016 Tectonic Evolution of the Durban Basin, MSc Structural Geology Dissertation, University of Leeds.

  • Paton, DA; van der Spuy, D; di Primio, R; Horsfield, B (2008) Tectonically induced adjustment of passive margin accommodation space; influence on the hydrocarbon potential of the Orange Basin, South Africa, AAPG Bulletin, 589-609.

  • Paton, DA; Macdonald, DIM; Underhill, JR (2006) Applicability of thin or thick skinned structural models in a region of multiple inversion episodes; southern South Africa, Journal of Structural Geology, 28(11), pp1933-1947.

  • Paton, DA (2006) Influence of crustal heterogeneity on normal fault dimensions and evolution: southern South Africa extensional system, Journal of Structural Geology, 28(5), pp868-886.

  • Macdonald, D; Gomez-Perez, I; Franzese, J; Spalleti, L; Lawver, L; Gahagan, L; Dalziel, I; Thomas, C; Trewin, N; Hole, M; Paton, DA (2003) Mesozoic break-up of SW Gondwana: implications for regional hydrocarbon potential of the southern South Atlantic, Marine and Petroleum Geology, 20(3-4), pp287-308

Related undergraduate subjects:

  • Geoscience