Middle to late Miocene Middle Eastern climate from stable oxygen and carbon isotope data, southern Alborz mountains, N Iran
Middle to late Miocene Middle Eastern climate from stable oxygen and carbon isotope data, southern Alborz mountains, N Iran
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DOI：
10.1016/j.epsl.2010.09.043
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发表时间：
2010-11
影响因子：
5.3
通讯作者：
P. Ballato;A. Mulch;A. Landgraf;M. Strecker;M. C. Dalconi;A. Friedrich;S. Tabatabaei
中科院分区：
文献类型：
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作者：
P. Ballato;A. Mulch;A. Landgraf;M. Strecker;M. C. Dalconi;A. Friedrich;S. Tabatabaei
伊朗北部的阿尔博尔兹山脉拦截和转移了北半球西风带着来自地中海和黑海的水汽，并形成了一道地形屏障，阻挡了来自里海北部的水汽。这意味着沿阿尔博尔茨山脉南部的陆地沉积(相对于喜马拉雅-喀喇昆仑地区的西藏和其他山区而言，北风的背风侧和西风带的迎风侧)可能跟踪过去水分和侵蚀制度的变化，并反映降雨模式。本文介绍了阿尔博尔茨山脉南部前陆中新世(约17.5-7.6 Ma)上红组的稳定同位素分析和粘土矿物研究结果。阿尔博尔茨山脉南部土壤和湖湖相碳酸盐的稳定氧碳同位素记录的变化表明：1)干旱的增加可能与阿尔博尔茨地形雨影的演化有关，在17.5-13.2 Ma之间变得更有效：2)13.2-10.3 Ma期间降水量稳步增加，11-10.3 Ma期间阿尔博尔茨山脉南坡的降雨量显著增加，这可能与南欧同时代湿相所揭示的北半球大气环流格局的扰动有关；(3)干旱度从9.6 Ma降至7.6 Ma，可能反映了降水季节性的增强。根据在南亚和印度观察到的约10 Ma以来的环境和气候变化，我们推测喜马拉雅-藏系的地形演化可能影响了中东晚中新世的气候。
The Alborz mountains of northern Iran intercept and divert the northern hemisphere westerlies carrying moisture from the Mediterranean and Black Sea, and form an orographic barrier to moisture sourced to the north in the Caspian Sea. This implies that terrestrial deposits along the southern Alborz mountains (leeward side of northerly winds and windward side of westerlies with the respect to Tibet and other mountainous terrain in the Himalayan–Karakoram realm) potentially track changes in past moisture and erosional regimes and mirror rainfall patterns. Here, we present results of a stable isotope analysis and clay mineral study of the Miocene (ca. 17.5–7.6Ma) Upper Red Formation in the foreland of the southern Alborz mountains. The changes recorded by stable oxygen and carbon isotope data from pedogenic and lacustrine/palustrine carbonate in the southern Alborz mountains suggest: 1) an increase in aridity possibly related to the evolution of the Alborz orographic rain shadow, which became more efficient between 17.5 and 13.2Ma; 2) a steady increase in precipitation between 13.2 and 10.3Ma with a significant increase in rainout along the southern slope of the Alborz mountains between 11 and 10.3Ma, possibly related to perturbations in atmospheric circulation pattern in the northern hemisphere as suggested by coeval wetter phases in southern Europe; and 3) a decrease in aridity from ca. 9.6 to 7.6Ma, possibly reflecting an increase in the seasonality of precipitation. Based on environmental and climatic changes observed across southern Asia and India starting from ca. 10Ma, we speculate that the topographic evolution of the Himalayan–Tibetan system might have affected the late Miocene climate in Middle East.