Multi-proxy constraints on the climatic significance of trace element records from a New Zealand speleothem
Multi-proxy constraints on the climatic significance of trace element records from a New Zealand speleothem
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DOI：
10.1016/s0012-821x(00)00115-1
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发表时间：
2000-06-30
影响因子：
5.3
通讯作者：
McCulloch, MT
中科院分区：
文献类型：
--
作者：
Hellstrom, JC;McCulloch, MT
报道了来自新西兰南岛的一个洞穴的微量元素浓度和铀同位素比率。TIMS对洞穴的铀系列测年表明，洞穴生长于31000年前至今，提供了最后一次冰川消融的连续记录。用电感耦合等离子体质谱测量的该洞穴中的微量元素丰度与Delta(13)C和其他测量变量以及由此推断的环境变化之间显示出很强的时间关系。锶和钡的浓度与洞穴上方植被覆盖范围和生产力的变化呈正相关。镁浓度似乎对地下水停留时间的变化做出了反应，假定与洞穴上方的有效降雨量成反比。U-234/U-238不平衡的程度似乎也随着水文变化而变化，与镁数据一起表明，冰川后区域有效降水量增加，达到约13000卡/年B.P.，这是先前推断的该区域森林面积在冰川后急剧增加约2000年后。因此，森林面积的增加不太可能是由降雨量的显著增加造成的，而且被认为主要是由区域温度的迅速上升所推动的，以距今15000个历年为中心。(C)2000 Elsevier Science B.V.保留所有权利。
Trace element concentrations and uranium isotope ratios are reported for a speleothem from the South Island of New Zealand. TIMS uranium-series dating of the speleothem indicates it to have grown from 31 000 years ago to the present, providing a continuous record of the last deglaciation. Trace element abundances measured in this speleothem using ICP-MS are found to exhibit strong temporal relationships with delta(13)C and other measured variables, and with the environmental changes inferred from them. Strontium and barium concentrations are positively correlated with inferred changes in the productivity and extent of vegetation cover above the cave. Magnesium concentration appears to have responded to changes in groundwater residence time, assumed to have an inverse relationship with effective meteoric precipitation above the cave. The degree of U-234/U-238 disequilibrium also appears to have varied in response to hydrological changes, and together with the magnesium data implies a post-glacial increase in regional effective precipitation to have culminated ca. 13 000 cal yr B.P., some 2000 years after a dramatic post-glacial increase in forest extent previously inferred for the region. This increase in forest extent is thus unlikely to have been caused by a significant increase in precipitation, and is assumed to have been driven predominantly by a rapid increase in regional temperature, centred on 15 000 calendar years before present. (C) 2000 Elsevier Science B.V. All rights reserved.