Sedimentary architecture and age of the Knights Point terrace, south Westland, New Zealand

Kostro, Fabian.

Well-preserved remnants of a raised marine terrace can be recognised at an altitude of 119m above sea-level in the coastal area south of Knights Point, South Westland. Excellent outcrops of this terrace allowed a detailed examination of marine cover beds and served as sample sites for optical luminescence dating. Facies analysis and quartz grains/pebbles with surface textures indicative of a high-energy subaqueous environment suggest the sedimentary succession is a deposit within a highly dynamic and storm influenced beach. Source areas of the terrace sediments include the local basement-cover sequences of South Westland. However, other detrital components are derived from Western Otago and Northern Fiordland, implying a transport northwards into the field area by a long shore current. Optical luminescence dating provided a burial age for the terrace sands of 123,0±7,0 ka, indicating a construction of the terrace during a sea-level transgression and highstand of the last interglacial (oxygen isotope stage 5e). The terrace coincides with other terraces of Southern Fiordland and South Taranaki, New Zealand and with coral reef terraces on the Huon Peninsula, New Guinea. The inferred uplift rate for the Knights Point area, west of the Alpine Fault, is calculated as 0,91mm/year and appears to support a theory by BULL & COOPER (1986) that ages of terraces may be inferred even where no other direct age estimates are available.

109 leaves : ill. (some col., 1 folded), maps (some col., 1 folded) ; 30 cm.

2003Kostro

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