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Title: Dynamic and Kinematic Evolution of a Fold-Thrust Belt with Emphasis on the Evolution of Deformation Front Structures
Author: Burberry, Caroline M.
ISNI:       0000 0001 3509 1940
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2009
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The deformation front of an orogen is defined as a zone or surface separating regions of different deformation styles or strain intensities. The large-scale development and migration of deformation front structures can be described and understood using critical wedge theory. At the foreland of a fold-thrust belt, the deformation front can be marked by a number of structures - an imbricate fan or frontal monocline, a ramp anticline or tip-line fold pair or a passive-roof duplex (triangle zone). This study considers two fold-thrust belts, the Zagros Simply Folded Belt, Iran and the Sawtooth Range, Montana. Both regions are developed in a passive margin carbonate sequence, overlain by a clastic succession. Remote sensing and field observations, combined with the interpretation of seismic data, are used to define the variation in fold structures within the belts and at the deformation fronts, and to constrain the migration of the deformation fronts. Palaeo-deformation fronts in the Zagros Simply Folded Belt are dominantly characterised by ramp anticlines, but the recent deformation front is marked in part by a reactivated fault structure above a salt diapir. The deformation front along the majority of the Sawtooth Range is a classic imbricate fan sequence, however, a triangle zone is observed in at least one segment of the belt. The development of each of these classes of structures is strongly influenced by the nature of inherited basement structures as well as by the mechanical stratigraphy of the sediment pile and the detachment type. The field and remote sensing components of the study are complemented by an analogue modelling study which is designed to investigate one of these factors, namely the effect of varying the geometry of an upper detachment horizon within the sediment pile. Results imply that the geometry of the upper detachment exerts a first order control on the development of deformation front structures. Triangle zones are found to develop where the upper detachment is narrow with respect to the width of the deformed zone. Conversely, foreland-verging structures develop where this upper detachment is wide with respect to the deformed zone.. When model results are compared to the field areas described above, this effect is shown to be a valid explanation for the structures developed. These results imply thatforeland triangle zones may be more common than currently documented, which has additional implications for hydrocarbon exploration and production. In addition, this thesis demonstrates the value of remote sensing methods for both hydrocarbon and mineral exploration.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available