Infrared-stimulated luminescence dating of late Quaternary aggradation surfaces and their deformation along an active fault, southern North Island of New Zealand

Conditional probability of rupture of the Wairarapa and Ōhariu faults, New Zealand

“…The fourth sample of Carne et al (2011) from Terrace B was collected from a silt c. 0.5 m above the gravel tread of Terrace B, and yielded an age of 7.490.6 ka (sample Wai-10b; Carne et al 2011). The age of this sample is about half that of the next youngest Terrace B sample of Carne et al (2011), and is stratigraphical consistent with the Wang & Grapes (2008) ages from the older Waiohine terrace. It is possible that the 7.490.6 ka age of sample Wai-10b (Carne et al 2011) provides a reasonable estimate for the age of abandonment of Terrace B, but there are two conflicting aspects of the sample that make it difficult to be sure of this.…”

“…The Waiohine terrace is regarded as equivalent to the Ohakean terrace, both surface and fill, elsewhere in the North Island (Palmer 1984). The age of aggradation, cessation of aggradation and subsequent abandonment of the Ohakean (0Waiohine) terrace has been the subject of a good deal of recent investigation (Formento-Trigilio et al 2003;Litchfield & Berryman 2005;Wang & Grapes 2008;Carne et al 2011; see also references cited therein). Litchfield & Berryman (2005) interpret the timing of abandonment of the Ohakean terrace in the three largest catchments in southeastern North Island to be 15Á20 ka.…”

“…Litchfield & Berryman (2005) interpret the timing of abandonment of the Ohakean terrace in the three largest catchments in southeastern North Island to be 15Á20 ka. Whereas, in some smaller subcatchments and/or locations closer to the range front, abandonment appears to be younger, c. 10Á12 ka (Wang & Grapes 2008;Little et al 2009). …”

“…At Waiohine River itself, Wang & Grapes (2008) report three luminescence ages for the Waiohine terrace from silts with some fine to medium gravel that directly overlie coarse alluvial gravel. The gravel content of the sampled silt sequence suggest that these samples are more likely to have been collected from the top of the aggradation fill package, or from overbank alluvial deposits, rather than from loess.…”

“…The gravel content of the sampled silt sequence suggest that these samples are more likely to have been collected from the top of the aggradation fill package, or from overbank alluvial deposits, rather than from loess. The three samples were all collected from within 0.6Á0.8 m from the ground surface, and have ages of 10.090.8, 10.291.2 and 13.090.9 ka (samples MR-1, Wh-2 and Wh-1, respectively, of Wang & Grapes 2008). At 2s uncertainty, all three samples overlap in the age range of 11.2Á11.6 ka.…”