Palaeo-seasonality of the last two millennia reconstructed from the oxygen isotope composition of carbonates and diatom silica from Nar Golu, central Turkey

QUATERNARY SCIENCE REVIEWS

卷:66

Article

Dean, Jonathan R.¹  Jones, Matthew D.¹  Leng, Melanie J.^2,3  Sloane, Hilary J.²  Roberts, C. Neil⁴  Woodbridge, Jessie⁴  Swann, George E. A.¹  Metcalfe, Sarah E.¹  Eastwood, Warren J.⁵  Yigitbasioglu, Hakan⁶ 

[1] Univ Nottingham, Sch Geog, Nottingham NG7 2RD, England

[2] British Geol Survey, NERC Isotope Geosci Lab, Nottingham NG12 5GG, England

[3] Univ Leicester, Dept Geol, Leicester LE1 7RH, Leics, England

[4] Univ Plymouth, Sch Geog Earth & Environm Sci, Plymouth PL4 8AA, Devon, England

[5] Univ Birmingham, Sch Geog Earth & Environm Sci, Birmingham B15 2TT, W Midlands, England

[6] Ankara Univ, Dept Geog, TR-06100 Ankara, Turkey

关键词: delta O-18;    Seasonality;    Near East;    Mass balance;    Energy-Dispersive X-ray Spectroscopy;    Lake sediments;   

DOI  :  10.1016/j.quascirev.2012.07.014

来源: Elsevier

【 摘 要 】

Carbonates and diatoms are rarely deposited together in lake sediments in sufficient quantities for the oxygen isotope composition (080) to be investigated simultaneously from both hosts. Here, delta O-18(carbonate) are compared to delta O-18(diatom) data from the varved sediments of Nar Goln, a closed lake in central Turkey, over the last 1710 years. Lake monitoring suggests carbonate is probably precipitated during May-June and delta O-18(carbonate) is a proxy for regional water balance. Diatom activity is mainly weighted towards the spring. At times between similar to 301 and 561 AD, while delta O-18(carbonate) values are the highest for the entire 1710 year period, suggesting summer drought, delta O-18(corrected-diatom) values are among the lowest. delta O-18(lakewater) values estimated for the times of diatom growth and carbonate precipitation show large differences. We suggest this could be explained by increased snowmelt that formed a freshwater lid on the lake at the time of peak diatom growth. Increased snowmelt is also inferred similar to 561-801 AD. From 801 AD to the present, precipitation is less winter-dominated, although increased snowmelt is inferred 921-1071 AD and in the latter part of the Little Ice Age (i.e. the mid to late 1800s AD). By combining oxygen isotope data from hosts that form in lakes at different times of the year, we show that such analyses can provide insights into palaeo-seasonality. (C) 2012 Elsevier Ltd. All rights reserved.

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