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theses

The goal of this study is to investigate how high-angle strike-slip faults affect deformation patterns during a subsequent phase of extension. To accomplish this goal, I use scaled experimental (analog) models with wet clay and two phases of deformation, an initial strike-slip phase and subsequent extensional phase. In Series 1 models, the extension direction varies during the second phase. In Series 2 models, the degree of the strike-slip-fault development varies during the first phase. The first-phase, right-lateral strike-slip deformation consists of subvertical Riedel shears, right-lateral R-shears and left-lateral R’-shears that strike ~15° and ~85°, respectively, relative to the trend of the deformation zone. In Series 1 models, the maximum extension direction relative to the strike of the pre-existing R- and R’-shears controls the likelihood of reactivation, the sense of slip on the reactivated faults, and the orientation of new normal faults. Pre-existing faults that are closer to being subperpendicular to the extension direction are more likely to be reactivated as high-angle normal faults. Additionally, some of the pre-existing R-shears are reactivated as tension gashes. Pre-existing faults that are closer to being subparallel to the extension direction are more likely to be reactivated as oblique-slip/strike-slip faults. Series 2 models show that new faults increasingly become more parallel to the orientation of R-shears as the pre-existing R-shears become better developed. In both Series 1 and 2 models, new faults commonly interact with pre-existing faults by cutting across, initiating at, and/or intersecting them. A pre-existing high-angle fault population can inhibit the development of new faults. A layered model shows that more faults cut the bottom of the clay than cut the top of the clay, suggesting that many faults nucleate at the base of the clay and propagate upward to the top of the clay. The reactivation of the pre-existing high-angle faults during a subsequent episode of extension and the interactions between pre-existing high-angle faults and new faults are comparable to those observed in the Suez rift system.

ETD_4904

M.S.

Includes bibliographical references

by Christian Satrianta Putra Ginting

doi:10.7282/T3KD1VZS

ETD graduate

The author owns the copyright to this work.