EAPSI:Structure and Deformation Rates of the North Canterbury Fold and Thrust Belt, South Island, New Zealand

Oakley David O, State College PA

Investigators

Abstract

The project focuses on active faulting within the North Canterbury region of the South Island of New Zealand. The project will be conducted in collaboration with Dr. Philip Barnes, a marine geologist at New Zealand?s National Institute of Water and Atmospheric Research who has done extensive work studying offshore faults. In addition to expertise, Dr. Barnes will provide access to a large database of offshore seismic reflection data, which is used to make images of the subsurface. The project will involve interpretation of this data, which will complement ongoing work on nearby onshore faults. Interpretation will involve identifying active faults in the seismic images, modeling the relationship between faulting at depth and folding of overlying rocks, and estimating rates of fault slip. Results will be used to identify active faults that may cause future earthquakes. They will also improve understanding of how folding of rocks, which commonly occurs in association with faults, can be used to infer the location of and amount of slip on the faults. Seismic reflection data will be interpreted to reveal details of fault-related folds and the possible reactivation of basement normal faults. Fold kinematic models, particularly trishear, will be tested for their applicability to these structures and used to produce restored cross-sections. Offshore results will be combined with onshore cross-sections, based on previous geologic mapping, to produce sections across the entire fold and thrust belt and to calculate total shortening. Growth strata will be restored to calculate rates of deformation, including the rates of slip on active faults, and these will be used along with deformation rates derived from previously-dated marine terraces along the coast to estimate rates of shortening across the transects. Finally, shortening and shortening rate calculations will be compared to the predictions of models for plate-boundary deformation within the region. This award is funded in collaboration with the Royal Society of New Zealand.