Sea surface temperature proxies (alkenones, foraminiferal Mg/Ca, and planktonic foraminiferal assemblage) and their implications in the Okinawa Trough

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• 作者：Ryoung Ah Kim ; Kyung Eun Lee ; Si Woong Bae
• 关键词：Sea surface temperature ; Okinawa Trough ; Alkenone ; Planktonic foraminiferal Mg/Ca ratio ; Planktonic foraminiferal assemblages
• 刊名：Progress in Earth and Planetary Science
• 出版年：2015
• 出版时间：December 2015
• 年：2015
• 卷：2
• 期：1
• 全文大小：1,422 KB
• 刊物类别：Earth Sciences, general; Geophysics/Geodesy; Planetology; Biogeosciences; Hydrogeology; Atmospheric
• 刊物主题：Earth Sciences, general; Geophysics/Geodesy; Planetology; Biogeosciences; Hydrogeology; Atmospheric Sciences;
• 出版者：Springer Berlin Heidelberg
• ISSN：2197-4284

文摘

We reviewed three sea surface temperature (SST) proxies in the Okinawa Trough (OT): alkenones, planktonic foraminiferal Mg/Ca, and planktonic foraminiferal assemblages. The seasonal and vertical distribution patterns of each proxy-related organism in the water column were reviewed to confirm the applicability of each proxy. In addition, current SSTs (Japan Oceanographic Data Center dataset from 1906 to 2003) were compared with core-top sediment temperatures reconstructed using the proxies. Temperatures calculated using the alkenone unsaturation index represent annual mean SSTs, and temperatures calculated using Mg/Ca of Globigerinoides ruber capture summer to autumn (June–November) SSTs. Core-top August SSTs calculated from planktonic foraminiferal assemblages corresponded well with the observed SSTs, but core-top February temperatures were ~3.6 °C warmer than the observed SSTs. SST proxy estimates from marine sediments dating back to the late Holocene (0–3 cal ky BP) and the last glacial maximum (18–21 cal ky BP) were compared. Comparisons between proxy SST estimates show that foraminiferal assemblage-based August SSTs were the warmest. Alkenone-based temperature estimates were lower than Mg/Ca-based temperature estimates, probably because the alkenone-based temperature represents the annual mean temperature, whereas the Mg/Ca-based temperature represents the summer–autumn mean temperature. February assemblage SSTs seem to be greatly affected by the statistical technique and/or database used. These results suggest that seasonality should be considered in past SST reconstruction using alkenone and Mg/Ca in the OT. The planktonic foraminiferal assemblage technique does not appear to be promising with respect to accurately reconstructing past SSTs (especially winter) in the OT. Habitat depth may not be an issue because both alkenone producers and G. ruber live at the upper surface mixed layer in the area.