Date

2013

Document Type

Dissertation

Degree

Doctor of Philosophy

Department

Earth and Environmental Sciences

First Adviser

Anastasio, David J.

Other advisers/committee members

Kodama, Kenneth P.; Picotti, Vincenzo

Abstract

Knowing the spatial and temporal variabilty of deformation in mountain belts is essential for understanding discrepancies between geodetic and geologic measurements of deformation and for accurately assessing seismic hazards. High-resolution deformational histories for three transects of the Northern Apennine mountain front, Italy, obtained from dated synorogenic growth strata, elucidate the spatial and temporal variabilty of thrust fault deformation in the Apennines since 3.0 Ma. Inverse and forward modeling of growth strata exposed in the Stirone River section shows the Salsomaggiore thrust exhibits a high frequency slip rate variability at 40-500 kyr timescales that is likely related to strain partitioning on connected imbricate thrusts. A high-resolution age model for the Pleistocene Enza growth strata section, which contains sedimentary facies spanning both marine and terrestrial environments, shows that the growth strata exposed at the Apennine mountain front not only record unsteady deformation but also record variable surface processes that can obscure true deformational behavior. A comparison of mountain front deformation at all three transects shows that unsteady deformation was asynchronous along orogenic strike between 1.0-3.0 Ma. A shift to synchronized deformation at all three transects is observed after 1.0 Ma. This shift also corresponds to a kinematic reorganization of the Apennine wedge and the initiation of thick-skinned thrusting. This kinematic reorganization was driven by climatically-driven overfilling of the Po foreland beginning at ~1.4 Ma, which had the effect of lowering the Apennine orogenic wedge taper and causing the wedge to respond by initiating out-of-sequence, basement involved reverse faulting localized at the present day Apennine mountain front.

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