Trace element variation in speleothem aragonite: potential for palaeoenvironmental reconstruction
Trace element variation in speleothem aragonite: potential for palaeoenvironmental reconstruction
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DOI：
10.1016/s0012-821x(01)00253-9
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发表时间：
2001-03-30
影响因子：
5.3
通讯作者：
Holmgren, K
中科院分区：
文献类型：
--
作者：
Finch, AA;Shaw, PA;Holmgren, K
年层积石笋中微量元素的变化具有记录长期、高分辨率古气候数据的潜力，前提是（1）碳酸盐中微量元素含量与气候之间的关系，以及（2）石笋生长机制。在这里，我们报告了二次离子质谱（西姆斯）研究文石洞穴（T7）从冷空气洞，南部非洲，实现小（妈妈）的空间分辨率和ppm精度。T7具有一系列精细可见的纹层，被认为是一年生到亚一年生的。本文建立了（1）的有用性西姆斯分析洞穴沉积物文石在空间分辨率和精度相关的气候研究，（2）微量元素在文石微米尺度上的分布和它们的关系，洞穴沉积物生长模型和（3）的潜力，文石洞穴沉积物编码的气候数据在亚年度分辨率。Sr/Ca和Ba/Ca的复杂的可重复振荡平行于洞穴沉积物的生长方向。然而，除了这种变化，我们观察到微量元素的振荡垂直于生长方向，并推断，文石微晶在speleothem横向，以及垂直分区。平行于生长方向的步进扫描显示出复杂的分区模式，由于文石的小规模横向异质性，很难从中提取简单的气候数据。然而，对整个数据集的时间序列分析揭示了Sr/Ca和Ba/Ca在与可见纹层的大小相匹配的尺度上的规律性周期。在此基础上，看来，在复杂的地球化学变化，有一个定期的环境控制，可能是水的吞吐量，因此降雨量的变化。(C)2001 Elsevier Science B. V.保留所有权利。
Trace element variation in annually laminated stalagmites has the potential to record long-term, high-resolution palaeoclimatic data provided both (1) the relationship between trace element content in the carbonate and the climate, and (2) the mechanism of stalagmite growth, are understood. Here we report a secondary ion mass spectrometry (SIMS) study of an aragonitic speleothem (T7) from Cold Air Cave, Southern Africa, which achieves small (mum) spatial resolution and ppm precision. T7 has a series of fine visible laminae believed to be annual to subannual. This article establishes (1) the usefulness of SIMS in analyzing speleothem aragonite at the spatial resolution and precision relevant to climatic studies, (2) the distribution of trace elements in aragonite on micron scales and their relationship to models for speleothem growth and (3) the potential of aragonite speleothems to encode climatic data at subannual resolution. Complex reproducible oscillations in Sr/Ca and Ba/Ca are observed parallel to the growth direction of the speleothem. However, in addition to this variability, we observe trace element oscillations perpendicular to the growth direction and infer that aragonite crystallites in the speleothem are laterally, as well as vertically zoned. Stepscans parallel to the growth direction demonstrate complex zoning patterns from which simple climatic data are difficult to extract due to small-scale lateral heterogeneity in the aragonite. However, time-series analysis of the whole data set reveals regular cycles in Sr/Ca and Ba/Ca at a scale that matches the magnitude of the visible laminae. On this basis, it appears that within the complex geochemical variability, there resides a regular environmental control, possibly variation in water throughput, hence rainfall. (C) 2001 Elsevier Science B.V. All rights reserved.