Egan, Stuart S (1988) Rheological, thermal and isostatic constraints on continental lithosphere extension and compression. Doctoral thesis, Keele University.

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Abstract

Deep seismic reflection data has shown the importance of low angle faults and detachments in continental extensional tectonics. A quantitative model of continental lithosphere extension is presented, incorporating geometric, thermal and isostatic components. The upper lithosphere extends by simple shear associated with low angle faults, while the lower lithosphere deforms by pure shear.
The resulting sedimentary basin geometry and crustal structure are dependent upon the amount of lithosphere extension, the distribution of the pure shear, the depth of
the horizontal detachment, the geometry of the low angle
fault and the isostatic response of the lithosphere during
rifting and thermal subsidence.
The Jeanne d' Arc basin, Newfoundland is most closely
represented by models incorporating the flexural isostatic
response of the lithosphere to applied loading.
Stratigraphic data shows that the basin was generated by
several pulses of extension and rifting was followed by
erosion. Modelling techniques are used to assess the
implications of these phenomena.
A two dimensional study of the rheological strength of the
lithosphere shows it to be determined by the interaction
between the pre-rift thermal state of the lithosphere, the
position of simple shear deformation with respect to that of pure shear, time since rifting and the rate of extension.
Model predictions of lithosphere shortening on low angle
thrusts have been combined with the extensional modelling
technique to explore the process of basin inversion. Model
predictions are compared with observations from the North
Celtic Sea Basin.
Extension on planar faults is modelled by considering the footwall and hanging wall as two interacting cantilevers, which flex in response to the isostatic forces created during extension. The construction has been applied to extension on a sequence of planar faults and predicts the familiar "domino-style" block rotation.

Item Type: Thesis (Doctoral)
Subjects: Q Science > QE Geology
Divisions: Faculty of Natural Sciences > School of Geography, Geology and the Environment
Contributors: Kusznir, Nick (Thesis advisor)
Depositing User: Lisa Bailey
Date Deposited: 09 Jul 2020 15:51
Last Modified: 09 Jul 2020 15:51
URI: https://eprints.keele.ac.uk/id/eprint/8374

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