Calibrations for benthic foraminiferal Mg/Ca paleothermometry and the carbonate ion hypothesis
Calibrations for benthic foraminiferal Mg/Ca paleothermometry and the carbonate ion hypothesis
复制标题
DOI：
10.1016/j.epsl.2006.07.041
复制
发表时间：
2006-10-30
影响因子：
5.3
通讯作者：
Nyland, B.
中科院分区：
文献类型：
--
作者：
Elderfield, H.;Yu, J.;Nyland, B.
对来自大西洋、挪威海、印度洋、阿拉伯海和太平洋的140个岩心-顶部样本进行了底栖有孔虫镁/钙比值测定，这些样本大多位于底层水温低于5摄氏度的地点。Mg/Ca比始终较低，通过类似于0.2 mmol/mol，在使用氧化和还原步骤清洁的样品中比使用氧化清洁。已鉴定出Cibicidoides物种之间的差异：Cibicidoides robertsonianus的Mg/Ca>Cibicidoides kullenbergi>Cibicidoides wuellerstorfi。与底层水温的比较支持C的Mg/Ca降低的观察结果。wuellerstorfi在温度低于类似3摄氏度相比，通过公布的校准和从其他Cibicidoides物种预测值。水文数据表明，碳酸根离子饱和度（Δ [CO 32-]）迅速下降低于此温度。已建立了C. δ [CO_（32-）]对Mg/Ca的经验灵敏度。wuellerstorfi为0.0086 +/- 0.0006 mmol/mol/μ mol/kg。一个新的应用程序，使用现代温度和末次冰期最高温度通过孔隙流体建模支持碳酸根离子饱和状态对镁掺入的影响。这可能会显著影响从有孔虫δ O-18和Mg/Ca温度获得的计算δ O-18（海水）。(c)2006 Elsevier B. V.保留所有权利。
Benthic foraminiferal magnesium/calcium ratios were determined on one hundred and forty core-top samples from the Atlantic Ocean, the Norwegian Sea, the Indian Ocean, the Arabian Sea and the Pacific Ocean, mostly at sites with bottom water temperatures below 5 degrees C. Mg/Ca ratios are consistently lower, by similar to 0.2 mmol/mol, in samples cleaned using oxidative and reductive steps than using oxidative cleaning. Differences between Cibicidoides species have been identified: Mg/Ca of Cibicidoides robertsonianus>Cibicidoides kullenbergi>Cibicidoides wuellerstorfi. Comparison with bottom water temperatures support observations of lowered Mg/Ca of C. wuellerstorfi at temperature below similar to 3 degrees C compared with values predicted by published calibrations and from other Cibicidoides species. Hydrographic data shows that carbonate ion saturation (Delta[CO32-]) decreases rapidly below this temperature. An empirical sensitivity of Delta[CO32-] on Mg/Ca has been established for C. wuellerstorfi of 0.0086 +/- 0.0006 mmol/mol/mu mol/kg. A novel application using modem temperatures and Last Glacial Maximum temperatures derived via pore fluid modelling supports a carbonate ion saturation state effect on Mg incorporation. This may significantly affect calculated delta O-18(seawater) obtained from foraminiferal delta O-18 and Mg/Ca temperature. (c) 2006 Elsevier B.V. All rights reserved.