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首页> 外文期刊>Geochemistry, geophysics, geosystems >Movement of the Intertropical Convergence Zone during the mid-pleistocene transition and the response of atmospheric and surface ocean circulations in the central equatorial Pacific
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Movement of the Intertropical Convergence Zone during the mid-pleistocene transition and the response of atmospheric and surface ocean circulations in the central equatorial Pacific

机译：上新世中期过渡期间热带融合带的运动以及赤道中太平洋太平洋大气和表层海洋环流的响应

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This paper investigates the causes of a brief, but prominent, cooling episode (1.1-0.8 Ma) that occurred in the equatorial upwelling region of the Atlantic and Pacific during the mid-Pleistocene transition (MPT) using temporal changes in dust provenance, regional hydrology, and surface productivity recorded in a deep-sea sediment core from the central equatorial Pacific. The Sr-87/Sr-86 and epsilon Nd values of the inorganic silicate fraction indicate deposition of dust from Australia and Central/South America before 0.8 Ma, but a gradual increase in Asian dust deposition after 0.8 Ma. The change in dust provenance was accompanied by an increased dust flux and a decrease in surface productivity and salinity. These changes can be explained by the southward movement of the Intertropical Convergence Zone (ITCZ) and North Equatorial Counter Current (NECC) and the direct influence of these features on the site after 0.8 Ma. Our results, together with previously published Atlantic data, suggest the northward position of the ITCZ between 1.1 and 0.9 Ma, and the southward position thereafter. The meridional movement of the ITCZ is in phase with the cooling and warming trend in upwelling regions in the equatorial Pacific and Atlantic, which suggests strengthening of southeast trades relative to its northern counterpart between 1.1 and 0.9 Ma as a plausible cause of this brief cooling event. The southward movement of the ITCZ from 0.9 to 0.8 Ma indicates more significant cooling in the Northern Hemisphere (NH) than in the Southern Hemisphere, which is supportive of the interpretation that the NH ice sheet expanded significantly and stabilized after 0.9 Ma.
机译：本文利用尘埃起源，区域水文学的时间变化，研究了中更新世过渡（MPT）期间大西洋和太平洋赤道上升区发生短暂但明显的降温事件（1.1-0.8 Ma）的原因。 ，并记录在赤道中部太平洋深海沉积物芯中的地表生产力。无机硅酸盐组分的Sr-87 / Sr-86和epsilon Nd值表明澳大利亚和中美洲/南美洲在0.8 Ma之前的尘埃沉积，但在0.8 Ma之后亚洲的尘埃沉积逐渐增加。灰尘来源的变化伴随着灰尘通量的增加以及表面生产率和盐度的降低。这些变化可以用热带辐合带（ITCZ）和北赤道逆流（NECC）的南移以及这些特征在0.8 Ma之后对站点的直接影响来解释。我们的结果以及先前发布的大西洋数据表明，ITCZ的北位置在1.1至0.9 Ma之间，此后向南。 ITCZ的子午线运动与赤道太平洋和大西洋上升流区域的降温和变暖趋势相一致，这表明东南贸易相对于北部的贸易相对增强，介于1.1Ma和0.9Ma之间，这可能是这一短暂降温事件的可能原因。 。 ITCZ从0.9到0.8 Ma的向南运动表明，北半球（NH）的降温要比南半球的显着，这支持了NH冰盖在0.9 Ma之后显着扩张和稳定的解释。

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