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GEOMETRY, KINEMATICS, EXHUMATION, AND SEDIMENTATION OF THE NORTHERN BOLIVIAN FOLD-THRUST-BELT-FORELAND BASIN SYSTEM.

Rak, Adam (2015) GEOMETRY, KINEMATICS, EXHUMATION, AND SEDIMENTATION OF THE NORTHERN BOLIVIAN FOLD-THRUST-BELT-FORELAND BASIN SYSTEM. Master's Thesis, University of Pittsburgh. (Unpublished)

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Abstract

Geometry and kinematics of deformation in the northern Bolivian Andes determine geologic map patterns, thermochronometer cooling signals, and synorogenic sediment distribution within the linked fold-thrust-belt-foreland basin system. To analyze the geometry, timing and rates of deformation we present a new cross section in northern Bolivia (Copacabana cross section) and perform thermokinematic modeling on a previously published, adjacent cross section (Beni cross section). Isostasy and erosion are applied to the sequentially deformed Beni cross section in northern Bolivia (McQuarrie et al., 2008) with kinematic modeling software Move. Applying isostasy and erosion to sequentially deformed balanced cross sections links the growth of hinterland structures to the developing foreland basins (FB) adjacent to fold-thrust belts (FTB), adding additional geologic constraints to modeled exhumation pathways. In our model, topography evolves and basins develop for each model step as deformation, erosion, and isostasy are applied; and are a direct function of the geometry and kinematics of the cross section. The model is constrained by the depth of the foreland and hinterland basins, geology at the surface, the depth and angle of the decollement, and the shape of the modern observed topography. Topography develops as thrusting occurs and loads the crust, producing a flexural wave and creating accommodation space in adjacent basins. Erosion of material above a newly generated topographic profile unloads the section while basin space is filled. Once the modelsufficiently duplicates geologic constraints, a grid of unique points is deformed with the model and used to determine displacement vectors for each 10 km shortening step. Displacement vectors, in conjunction with a prescribed time interval for each step, determine a velocity field that can be used in a modified version of the advection diffusion modeling software Pecube. Thermochronometer cooling ages predicted using this method are based on deformation rates, geometry, topography, and thermal parameters, and offer insight into possible rates of deformation, erosion, and deposition throughout FTB and FB development. Incorporating erosion, deposition, and isostasy in sequentially deformed balanced cross sections highlights the spatiotemporal aspects of sedimentary wedge propagation, identifies external negative buoyancy affects, and provides additional geologic constraints to modeled exhumation pathways.


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Details

Item Type: University of Pittsburgh ETD
Status: Unpublished
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Rak, Adamajr137@pitt.eduAJR137
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairMcQuarrie, Nadinenmcq@pitt.eduNMCQ
Committee MemberHarbert, Williamharbert@pitt.eduHARBERT
Committee MemberWerne, Josefjwerne@pitt.eduJWERNE
Date: 9 September 2015
Date Type: Publication
Defense Date: 28 May 2015
Approval Date: 9 September 2015
Submission Date: 9 June 2015
Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
Number of Pages: 135
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Geology and Planetary Science
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: English
Date Deposited: 09 Sep 2015 14:07
Last Modified: 15 Nov 2016 14:28
URI: http://d-scholarship.pitt.edu/id/eprint/25366

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