Thesis (M.Sc.)--Memorial University of Newfoundland, 1997. / Bibliography: leaves 112-115. Also available online.

Thesis (M.S.) -- University of Tennessee, Knoxville, 2005. / Title from title page screen (viewed on Feb. 6, 2006). Thesis advisor: William M. Dunne. Vita. Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 45-49). Also available via the World Wide Web.

Thesis (M.S.)--Ohio University, June, 2004. / Title from PDF t.p. Includes bibliographical references (p. 101-108)

Thesis (M.S.)--Humboldt State University, 2007. / Includes bibliographical references (leaves 64-67). Also available via Humboldt Digital Scholar.

This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Thesis: Ph. D., Massachusetts Institute of Technology, Department of Earth and Planetary Science, 1977 / Vita. / Bibliography : leaves 135-137. / By Robert Wayne Siegfried, II. / Ph. D. / Ph. D. Massachusetts Institute of Technology, Department of Earth and Planetary Science

This dissertation investigates the temporal and spatial variations in deformation of the Calabrian forearc during the evolution of the subduction-rollback system. In addition to contributing new data to the area, I develop three strategies for understanding recent and active deformation by linking long-term structural data with short-term geomorphological data. First, setting a “baseline” of deformation is important when studying plate boundaries. Through the structural mapping of an uplifted forearc basin, I conclude that rapid rollback is characterized by tectonic quiescence in the Calabrian forearc when it is located far from collision (from ~12 Ma – ~5 Ma). This “baseline” provides a framework from which I interpret younger phases of deformation. In the middle Pliocene (~5-4 Ma), an arc-parallel shortening event characterizes the first stage of forearc collision in my field area. These folded sediments are later tilted, but structural data from the field cannot constrain the age or structure responsible for this youngest phase of deformation. The Neto River dissects this tilted surface opening up the possibly of linking structural data with geomorphic data from river erosion. I collected a transect of river sediment samples for 10Be analysis to determine variation in catchment-wide erosion rates through the modern day deformation. I, then, developed a numerical model that describes changes in erosion rate through time with the structural growth of the tilted surface. The model is the first of its kind to use catchment-wide erosion rates to constrain a structural model. The model results constrain the age of the beginning of deformation to 850 ka and suggest that a fold with a migrating hinge caused tilting of the surface. The model provides the basis for my hypothesis that the forearc is experiencing an arc-perpendicular shortening strain, which contradicts conclusions from GPS data and the well-documented extension in the western part of the forearc. To further investigate surficial deformation, I carry out geomorphic analyses of 87 river drainages. I interpret my findings in terms of structural framework and find that surficial deformation varies tremendously from east to west. The rivers draining eastward are characterized by low concavities and higher erosion rates, consistent with shortening. While just 50 km away, the westward-draining rivers are characterized by high concavities and lower erosion rates, consistent with extension. Overall, the drainages are shifting from east-draining to west-draining, likely due to the topographic growth that decreases concavities on the eastern side. Although a new interpretation, this finding is consistent with previous structural, paleomagnetic, and seismological datasets. In each of the chapters, I interpret the structural and geomorphic data in a regional framework. This extra step is critical in interpreting deformation along active plate boundaries because it is highly variable and can be seemingly contradictory. In my final chapter, I present a cross section of the plate boundary that incorporates my data and interpretations from the geomorphic results and the most recent structural event as well as data from multiple other sources (GPS, seismological, paleomagnetics, structural, tomographic, geomorphic, etc.). This approach confirms the importance of boundary conditions on deformation in a subduction-rollback system. More intriguingly, the cross-section highlights the spatial variations along the surface and with depth suggesting that there is significant interplay between active structures.

Surface and subsurface data from the Sulaiman thrust belt show that nearly all the 10 km thick sequence of dominantly platform (>7 km) and molasse strata is detached at the deformation front. These strata thicken tectonically to a minimum of 20 km in the hinterland of the Sulaiman fold belt without significant thrust faults at the surface. The balanced structural cross-:section suggests that the tectonic uplift in the Sulaiman fold belt is a result of thin-skinned, passive-roof duplex style of deformation. The duplex sequence of Jurassic and older rocks is separated from the roof sequence by a passive-back thrust in thick Cretaceous shales. The passive-roof sequence remains intact for about 150 km and becomes emergent along a passive-back thrust in the hinterland. The structures are expressed at the surface by fault-related folds in the foreland and out-of-sequence structures (secondary faults and related pop-ups) in the interior. The duplex structure varies from fault-bend folds to anticlinal stacks, and hinterland dipping duplexes. Progressive deformation reveals a series of structural and geometrical features including: (1) broad concentric folding at the fault tip; (2) development of a passive-roof and duplex sequence; (2) forward propagation of the duplex as critical taper is achieved; (4) tear faults and extensional normal faults within the overthrust wedge; and (5) out of sequence (secondary) thrusting. The 349 km long balanced cross-section from the Sulaiman fold belt restores to an original length of 727 km that provides 378 km of shortening in the cover strata of the Indian subcontinent. Minimum estimate of shortening is 328 km. Modelling of the Bouguer gravity profile from the Sulaiman foredeep across the Indian/ Afghan collision zone suggests the depth to the Moho at the Sulaiman deformation front is about 36 km. Depth to Moho increases northward with a gentle gradient of 1.1° (20 m/km) for 280 km to the hinterland where the depth to the Moho is about 42 km. About 150 km north across the Khojak flysch the Moho gradient steepens abruptly to about 7.8° (136 m/km) to attain an average depth of about 57 km in eastern Afghanistan. This suggests that the Sulaiman fold belt is underlain by transitional crust associated with the western passive margin of the Indian subcontinent. / Graduation date: 1992

Thesis (M.S.)--Western Washington University, 2010. / Includes bibliographical references (leaves 98-102). Also issued online.

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 128-140).