中国热带雷州半岛北部地区末次冰期气候变化的特征与机制
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本文为国家自然科学基金(41071137,40671189)、广东省自然科学基金(S2011010003413,8151063101000044)及广东省高等学校高层次人才项目等资助成果。


Variation and mechanism of paleoclimate in the Last Glaciation in the tropic northern Leizhou Peninsula in South China
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    摘要:

    本文通过对雷州半岛北部屋山和下录泥炭沉积剖面,以及泉水河湖相沉积剖面沉积物有机质δ13C分析,重建了我国热带北部地区48~10 cal ka BP期间的气候变化历史。通过与三个剖面的烧失量(LOI)、有机质含量(OM)、腐殖化度(HD)、低频磁化率(χlf)、干密度(DD)等气候代用指标的对比分析:δ13Corg低值指示气候较为暖湿,东亚夏季风较强;δ13Corg高值则指示气候较为冷干,东亚夏季风较弱。研究表明我国热带北部地区在48~28 cal ka BP之间气候较为暖湿。在22 cal ka BP(或20 cal ka BP)左右,研究区域气候发生急剧变化,其中最干冷的阶段出现在18~16 cal ka BP,反映了东亚夏季风的衰弱,可能与末次盛冰期(LGM)的到来有一定关系。12 cal ka BP之后该区域气候又逐渐转为暖湿。在48~10 cal ka BP之间,三个剖面的δ13Corg值的若干正偏方向的扰动则表明C4植被或者偏正的C3植被的扩张,这些千年尺度的正偏扰动可能与Heinrich 事件以及格陵兰冰芯和葫芦洞石笋所检测出来的千年尺度的冷干事件有关。研究还发现,三个研究剖面的δ13Corg记录反映的我国热带北部气候变化与南半球巴西石笋记录的南美季风变化呈反位相关系,这表明我国热带地区末次冰期的气候变化主要与太阳辐射的变化,以及受太阳辐射驱动的热带辐合带(ITCZ)的迁移有关。ITCZ的迁移可能会引起哈德莱环流经向上分布的不对称,进而改变经向上的水汽传输,使得南北半球低纬度地区气候变化相反。南半球高纬度地区也可能通过“推拉”机制影响到雷州半岛北部地区的气候变化。

    Abstract:

    Based on the analyses of bulk organic δ13C for the Wushan and the Xialu peat cores, as well as a fluvial or swamp composed sequence, the Quanshui section, from the north of Leizhou Peninsula, we reconstructed the history of climate changes between 48.0 and 10 cal ka BP in the north tropic region in South China. On basis of comparison with the multi-proxy climatic records such as the loss on ignition (LOI), the content of organic matter (OM), the degree of humification (HD), and the Low field magnetic susceptibility (χlf) of three profiles, we interpret that more negative bulk organic δ13C values would suggest wetter and warmer conditions, implying a strengthening of the East Asian (EA) summer monsoon, whereas less negative δ13C values indicate drier and cooler conditions, suggesting a weakening of the EA summer monsoon. A warm and wet period occurred between 48.0 and 28 cal ka BP. A climate shift occurred at 22 (or 20) cal ka BP, and the driest and coldest period occurred between 18.0 and 16.0 cal ka BP ,which indicate a weak EA summer monsoon and may be related to the last glacial maximum (LGM). After 12.0 cal ka BP, the climate changed towards wetter and warmer conditions. From 48.0 to 10.0 cal ka BP, several short positive δ13Corg excursions indicate the expansion of C4 plants or the C3 plants characterized by more positive δ13Corg value. These excursions shows a similarity with the Heinrich events and other cold millennial-scale oscillations evidenced from a Greenland ice core and the Chinese stalagmite record. We also demonstrate that the variations of climate reflected by bulk δ13Corg records show an inverse correlation with the South American monsoon in the South Hemisphere. We deduce that the solar radiation, as well as the solar radiation-driven the shift of the intertropical convergence zone (ITCZ), may have played a role in the climate changes in the Last Glaciation in north tropic China. The migration of ITCZ may have caused meridional asymmetry in the Hadley circulation, and would change meridional moisture transport. This will make the climate changes in northern low latitudes show an inverse correlation with southern low latitudes. Besides, high latitudes of the southern hemisphere may play a key role in the climate changes of Leizhou Peninsula through the mechanism of “push” or “pull”.

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曹家元.2013.中国热带雷州半岛北部地区末次冰期气候变化的特征与机制[J].地质学报,87(8):1179-1192.
caojiayuan.2013. Variation and mechanism of paleoclimate in the Last Glaciation in the tropic northern Leizhou Peninsula in South China[J]. Acta Geologica Sinica,87(8):1179-1192.

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  • 收稿日期:2012-05-19
  • 最后修改日期:2012-10-18
  • 录用日期:2013-09-11
  • 在线发布日期: 2013-09-16
  • 出版日期: