Climate reconstruction from paired oxygen-isotope analyses of chironomid larval head capsules and endogenic carbonate (Hawes Water, UK) - Potential and problems

QUATERNARY SCIENCE REVIEWS

卷:270

Article

Lombino, Alex¹  Atkinson, Tim^1,2  Brooks, Stephen J.³  Grocke, Darren R.⁴  Holmes, Jonathan¹  Jones, Vivienne J.¹  Marshall, Jim D.⁵  Nierop, Klaas G. J.^6,7  Thomas, Zoe⁸ 

[1] UCL, Environm Change Res Ctr, Dept Geog, Gower St, London WC1E 6BT, England

[2] UCL, Dept Earth Sci, Gower St, London WC1E 6BT, England

[3] Nat Hist Museum, Dept Life Sci, Cromwell Rd, London SW7 5BD, England

[4] Univ Durham, Dept Earth Sci, South Rd, Durham DH1 3LE, England

[5] Univ Liverpool, Dept Earth Ocean & Ecol Sci, Liverpool L69 3GP, Merseyside, England

[6] Univ Utrecht, Fac Geosci, Dept Earth Sci, Princetonlaan 8, NL-3584 CB Utrecht, Netherlands

[7] Univ Utrecht, Fac Geosci, GeoLab, Princetonlaan 8, NL-3584 CB Utrecht, Netherlands

[8] Univ New South Wales, Sch Biol Earth & Environm Sci, Sydney, NSW 2052, Australia

关键词: Oxygen isotopes;    Chironomids;    Late glacial;    NW England;    Lake sediments;    Palaeotemperature;   

DOI  :  10.1016/j.quascirev.2021.107160

来源: Elsevier

【 摘 要 】

Temperature and the oxygen isotopic composition (delta O-18) of meteoric water are both important palaeoclimatic variables, but separating their influences on proxies such as the delta O-18 of lake carbonates is often problematic. The large temperature variations that are known to have occurred in the northern mid-latitudes during the Late Glacial make this interval an excellent test for a novel approach that combines oxygen-isotope analyses of chironomid larval head capsules with co-occurring endogenic carbonate. We apply this approach to a Late Glacial lake sediment sequence from Hawes Water (NW England). Oxygen-isotope values in chironomid head capsules show marked variations during the Late Glacial that are similar to the oxygen isotope record from endogenic carbonate. However, summer temperature reconstructions based on the paired isotope values and fractionation between chironomids and calcite yield values between -20 and -4 degrees C, which are unrealistic and far lower than reconstructions based on chironomid assemblages at the same site. The composition of a limited number of samples of fossil chironomid larval head capsules determined using Pyrolysis gas-chromatography mass spectrometry indicates the presence of aliphatic geopolymers, suggesting that diagenetic alteration of the head capsules has systematically biased the isotope-derived temperature estimates. However, a similar trend in the isotope records of the two sources suggests that a palaeoclimate signal is still preserved. (C) 2021 The Authors. Published by Elsevier Ltd.

【 授权许可】

Free