A ca. 800-Year Lithologic Record of Drought from Sub-annually Laminated Lake Sediment, East Java
A ca. 800-Year Lithologic Record of Drought from Sub-annually Laminated Lake Sediment, East Java
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大约。
DOI：
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发表时间：
2006
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通讯作者：
D. Schnurrenberger
中科院分区：
文献类型：
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作者：
S. Crausbay;J. Russell;D. Schnurrenberger
对爪哇岛玛珥湖Ranu Lalanan的次年度层积岩心进行岩石地层学分析，记录了该湖在过去约100年的化学和水平衡发生了相当大的变化。800个日历年。组合物的黑暗（碎屑）和轻（硅藻和/或碳酸钙矿物）对联表明，这些叠层形成响应季节性变化的降雨和水柱推翻在湖中。碳酸钙在岩芯中是不连续的，当它出现时，它在碳酸盐相和元素组成（低镁方解石镁方解石和文石）中变化，有时突然变化。自生碳酸钙中Mg/Ca变化与δ 18 O变化之间存在显著的相关性，表明该盆地对水文变化具有高度的敏感性。岩性数据表明碳酸钙沉淀，从而记录了旱季的水文条件-一个降雨异常与ENSO阶段高度相关的季节。我们的碳酸盐为基础的镁/钙记录显示蒸发浓度的变化在准季节性的频率为过去的CA。八百年了。我们的记录显示了两个几十年的干旱期。1275-1325和CA。公元1450-1650年-后者特别强大和/或延长。我们的记录还显示了干旱频率在公元1650年左右可能发生的变化，其中碳酸钙降水和Mg/Ca变化的周期从几十年变化到年际变化。鉴于东爪哇现代干旱与ENSO变化之间的密切相关性，我们的干旱记录可能表明大约350年前ENSO系统行为的政权转变。最后，我们的记录和其他记录之间的比较表明，百年和亚百年尺度的ENSO变化与全球平均气候状态的变化没有很强的联系。
Lithostratigraphic analyses of a sub-annually laminated core from Ranu Lamongan, a maar lake on the island of Java, document considerable changes in the lake’s chemistry and water balance over the past ca. 800 calendar years. Composition of the dark (clastics) and light (diatoms and/or calcium carbonate minerals) couplets suggests that these laminations form in response to seasonal changes in rainfall and water-column overturn in the lake. Calcium carbonate is not continuous in the core, and when it occurs it varies, sometimes abruptly, in carbonate phase and elemental composition (low Mg-calcite Mg-calcite, and aragonite). A significant correlation between Mg/Ca changes and δ18O variations in authigenic calcium carbonate suggest the basin is highly sensitive to hydrologic variation. Lithologic data suggest calcium carbonate precipitates and thus records hydrologic conditions during the dry season – a season in which rainfall anomalies are highly correlated with the phase of ENSO. Our carbonate-based record of Mg/Ca shows variability in evaporative concentration on a quasi-seasonal frequency for the past ca. 800 years. Our record shows two multi-decadal periods of drought – ca. 1275–1325 and ca. 1450–1650 CE – the latter of which was especially strong and/or prolonged. Our record also shows a possible change in drought frequency at around 1650 CE, in which periods of calcium carbonate precipitation and Mg/Ca change shifted from multi-decadal to interannual variability. Given the strong correlations between modern-day drought in East Java and ENSO variability, our drought record may indicate a regime shift in the behavior of the ENSO system about 350 years ago. Finally, comparisons between our record and others suggest that variation in ENSO on centennial and sub-centennial scales is not strongly associated with changes in the global mean climate state.