Uplift rate of marine terraces and anticlinal growth along the North Canterbury fold and thrust belt, New Zealand

This study measures the uplift rates of a flight of marine terraces along the Glenafric coastal region of the South Island of New Zealand, which will provide a context for how local fold growth in the North Canterbury fold and thrust belt (NCFTB) contributes to local uplift rates. Several methods were used to measure uplift rate of the marine terraces: 1) collecting shell samples for AAR dating in order to refine terrace ages; 2) use of DGPS surveys to collect the elevations of marine terrace inner edges and possible marine terrace erosional surfaces; 3) creating several cross-sections based on the DGPS surveys to refine terrace boundaries; and 4) calculating the uplift rate of all marine terraces along the North Canterbury fold and thrust belt to determine possible structural influence on local uplift. Amino acid rasterization (AAR) and optically stimulated luminescence (OSL) dating techniques were used to date the youngest terrace, Qt3, at ~100 ka, placing Qt3 at marine isotope stage (MIS) 5c. Correlations to sea level highstands from inner edge elevation projections from the cross-sections were used to date Qt2 at ~120 ka and Qt1 at ~210 ka. Correlations of inner edge elevations to the Cass and Montserrat anticlines show that inner edges closest to the anticlinal axis were generally higher in elevation than points farther from the anticlinal axis. However, this was not the case for all GPS survey points as GPS surveys in the southern region of the field exhibit low elevations and are in close proximity to the anticlinal crest. Therefore another mechanism must contribute to marine terrace uplift as well.