Graham, I.J.; Alloway, B.V.; Cochran, U.A.; Cook, R.A.; Ditchburn, R.G.; Mildenhall, D.C.; Morgenstern, U.; Prior, C.A. 2005 Sedimentology, geochronology and micropaleontology of post- and immediately pre-European Lake Tekapo sediment (based on analysis of core L1395) . Lower Hutt: Institute of Geological & Nuclear Sciences. Institute of Geological & Nuclear Sciences science report 2005/34 82 p.
Abstract: This report details sedimentological, geochronological and micropaleontological research on Lake Tekapo sediment core L1395, extracted by NIWA in November 1991. In addition to assessing the reliability of classical ‘varve’ counting to determine sedimentation rates, the report outlines various options for dating glacial lake sediments in southern New Zealand, and makes recommendations with respect to planned drilling of nearby Lake Pukaki. An ambitious project was launched in July 2002 within GNS’s ‘Global Change Through Time’ PGST research program (C05X0202) to investigate New Zealand’s Holocene climatic record via a deep drill core into Lake Pukaki sediment. Lake Pukaki, a pro-glacial lake similar to Lake Tekapo is located on the eastern side of the Southern Alps adjacent to Mount Cook (Aoraki), and has received ca. 400m of sediment from its catchment since forming ca. 16 k.y. ago. Its sedimentary record, therefore, has the potential to reveal a high resolution record of paleo-climatic fluctuations, provided that the appropriate climatic proxies can be identified and a robust and precise chronology can be established. This report focuses on sedimentological analysis, the principal radiometric methods available for dating lacustrine sediments within a 0-50 k.y. time-frame, and preliminary micropaleontological investigations. Lake Tekapo contains an almost complete record of sedimentation covering the past ca. 16 k.y. and hence also a record of storm events and more subtle changes in climate during that time. However, the temperate climate of the region contrasts with that of many previous lake bed studies in North America and Europe, creating new challenges for deriving robust climate proxies from the sedimentary record. (auth)