Abstract
Abstract. The accurate and precise reconstruction of Quaternary climate as well as the events that punctuate it is an important driver of the study of lake sediment archives. However, until recently lake sediment-based palaeoclimate reconstructions have largely concentrated on Northern Hemisphere lake sequences due to a scarcity of continuous and high-resolution lake sediment sequences from the Southern Hemisphere, especially from the southern mid-latitudes. In this context, the deep maar lakes of the Auckland Volcanic Field of northern New Zealand are significant as several contain continuous and well-laminated sediment sequences. Onepoto Basin potentially contains the longest temporal lake sediment record from the Auckland Volcanic Field (AVF), spanning from Marine Isotope Stage 6e (MIS 6e) to the early Holocene when lacustrine sedimentation was terminated by marine breach of the south-western crater tuff ring associated with post-glacial sea-level rise. The Onepoto record consists of two new, overlapping cores spanning ca. 73 m combined with archive material in a complete composite stratigraphy. Tephrochronology and 14C dating provide the fundamental chronological framework for the core, with magnetic relative palaeo-intensity variability downcore, and meteoric 10Be influx into the palaeolake to refine the chronology. The µ-XRF (micro X-ray fluorescence) downcore variability for the entirety of the lake sediment sequence has been established with measurement of a range of proxies for climate currently underway. This work will produce the first continuous record of the last 200 kyr of palaeoclimate from northern New Zealand to date.
Highlights
Deep-lake sediment archives allow for the development of a more comprehensive interpretation of past climatic and environmental evolution during the Quaternary than other continental climate archives, such as tree rings, peat bogs, and speleothems, and are often less prone to hiatuses than loess and fluvial deposits (Zolitschka and Enters, 2009)
A first scientific drilling campaign at Onepoto Basin in the years 2001/2002 produced a continuous lake sediment sequence to a depth of ∼ 60 m below the surface
Age markers for the early stage of the lake and its eruptive formation are provided through Auckland Volcanic Field (AVF)-sourced basaltic ejecta (AVF B/ AVF C) and the lava at the base (AVF D)
Summary
Deep-lake sediment archives allow for the development of a more comprehensive interpretation of past climatic and environmental evolution during the Quaternary than other continental climate archives, such as tree rings, peat bogs, and speleothems, and are often less prone to hiatuses than loess and fluvial deposits (Zolitschka and Enters, 2009). In contrast to the Northern Hemisphere where long, high-resolution late Quaternary terrestrial palaeoclimate archives are common and are well studied (e.g., the Eifel maar lakes in Germany; Sirocko et al, 2016), their New Zealand lake counterparts are few, often show poor resolution, and suffer from age controversies (e.g., Molloy et al, 2009; Hopkins et al, 2017). The Auckland maar lakes are crucial in the context of the Southern Hemisphere mid-latitudes as they contain archives representative of past south-western Pacific climate variability (Alloway et al, 2007). Läuchli et al.: Composite development and stratigraphy of the Onepoto maar lake sediment sequence
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