Proposed changes in seasonality of climate during the Lateglacial and Holocene at Lake Zeribar, Iran
Proposed changes in seasonality of climate during the Lateglacial and Holocene at Lake Zeribar, Iran
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伊朗泽里巴尔湖晚冰期和全新世气候季节性的拟议变化
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
E. Ito
中科院分区：
文献类型：
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作者：
Lora R. Stevens;Herbert E. Wright;E. Ito
石灰质沉积物跨越过去的13万年，从泽里巴尔湖，伊朗西部，进行了采样稳定同位素分析，作为一种手段，增强早期的气候解释的基础上花粉和宏体化石。晚冰期寒冷干燥，支持半沙漠植被和高度集中的湖水。由于寒冷导致的低蒸发率导致了长时间的停留和高湖站。在全新世早期，随着低温和干旱的改善，高地植被变成了阿月浑子栎稀树草原。湖平面下降，以应对增加蒸散。湖相方解石在此期间的低氧同位素值被解释为冬季水分的贡献相对增加，而不是有效水分的总体变化。橡树花粉的逐渐增加，在2.7kaBP的信号增加有效水分的水平类似于今天。同时δ18O值增加。反映了更大比例的富含18O的春雨。建立了6 ka BP的现代降水量和季节分布。4.5 ka BP时，降水短暂恢复到冬季降水，导致干旱程度暂时增加。δ 13 C、碳酸盐沉积和δ 18 O值之间的协方差表明，湖泊生产力与这些季节性气候变化有关。
Calcareous sediments spanning the last 13 ka from Lake Zeribar, western Iran, were sampled for stable-isotope analysis as a means of augmenting earlier climatic interpretations based on pollen and macrofossils. The Lateglacial period was cold and dry, supporting semi-desert vegetation and highly concentrated lake water. Low evaporation rates due to the cold resulted in long residence times and high lake stands. Durinig the early Holocene, the upland vegetation changed to a pistachio-oak savanna as low temperatures and aridity ameliorated. Lake level dropped in response to increased evapotranspiration. The low oxygen-isotope values of lacustrine calcite during this period are interpreted as a relative increase in the contributioni of winiter moisture rather than overall changes in effective moisture. A gradual increase in oak pollen at ∼7 ka BP signalled the increase in effective moisture to levels similar to those of today. At the same time the δ18O values increased. reflecting a greater percentage of 18O-enriched spring rains. Modern values and seasonal distribution of precipitation were established by 6 ka BP. A short-lived return to winter-only precipitation occuiTed at ∼4.5 ka BP and resulted in a temporary increase in aridity. The covariance among δ13C, carbonate deposition and δ18O values suggests that lake productivity is linked to these seasonal climatic changes.