Orbital forcing of the East Antarctic ice sheet during the Pliocene and Early Pleistocene-猫眼课题宝

DOI：

10.1038/ngeo2273

发表时间：

2014-10

期刊：

Nature Geoscience

影响因子：

18.3

通讯作者：

中科院分区：

地球科学1区

文献类型：

作者：

M. Patterson;R. McKay;T. Naish;C. Escutia;F. Jiménez-Espejo;M. Raymo;S. Meyers;L. Tauxe;H. Brinkhuis;A. Klaus;Annick Fehr;J. Bendle;P. Bijl;S. Bohaty;S. Carr;R. Dunbar;J. Flores;J. Gonzàlez;T. Hayden;M. Iwai;K. Katsuki;G. Kong;M. Nakai;M. Olney;S. Passchier;S. Pekar;J. Pross;C. Riesselman;U. Röhl;Toyusaburo Sakai;P. Shrivastava;C. Stickley;S. Sugasaki;S. Tuo;T. Flierdt;K. Welsh;T. Williams;M. Yamane

上新世和早更新世，在530万年前到80万年前之间，跨越了一个从全球气候状态的转变，从比现在高2-3 °C，北方半球的冰盖有限，到以两极大陆规模冰川为特征的气候状态。这些冰盖的生长和衰退是由地球绕太阳轨道的变化来决定的。然而，轨道强迫对冰盖的影响的性质尚不清楚，特别是考虑到在全球冰量和海平面的地质记录中没有强烈的2万年岁差信号。在这里，我们展示了430万年前到220万年前，在南极洲东部冰盖附近，威尔克斯冰下盆地附近，冰山筏碎片在近海堆积的速度记录。我们推断，最大的冰山碎片积累与冰盖边缘退缩过程中增强的冰山产犊。在430万年前到350万年前的较温暖的记录部分，光谱分析显示了大约4万年的主要周期性。随后，十万年和两万年信号的威力增强。我们认为，当南大洋在350万年前至250万年前冷却时，常年海冰场的发展限制了冰盖的海洋强迫。越过这个门槛后，东南极冰盖的大幅度撤退只发生在南半球夏季日照最大值，控制的岁差周期。

The Pliocene and Early Pleistocene, between 5.3 and 0.8 million years ago, span a transition from a global climate state that was 2–3 °C warmer than present with limited ice sheets in the Northern Hemisphere to one that was characterized by continental-scale glaciations at both poles. Growth and decay of these ice sheets was paced by variations in the Earth’s orbit around the Sun. However, the nature of the influence of orbital forcing on the ice sheets is unclear, particularly in light of the absence of a strong 20,000-year precession signal in geologic records of global ice volume and sea level. Here we present a record of the rate of accumulation of iceberg-rafted debris offshore from the East Antarctic ice sheet, adjacent to the Wilkes Subglacial Basin, between 4.3 and 2.2 million years ago. We infer that maximum iceberg debris accumulation is associated with the enhanced calving of icebergs during ice-sheet margin retreat. In the warmer part of the record, between 4.3 and 3.5 million years ago, spectral analyses show a dominant periodicity of about 40,000 years. Subsequently, the powers of the 100,000-year and 20,000-year signals strengthen. We suggest that, as the Southern Ocean cooled between 3.5 and 2.5 million years ago, the development of a perennial sea-ice field limited the oceanic forcing of the ice sheet. After this threshold was crossed, substantial retreat of the East Antarctic ice sheet occurred only during austral summer insolation maxima, as controlled by the precession cycle.

Orbital forcing of the East Antarctic ice sheet during the Pliocene and Early Pleistocene

文献摘要

被引文献

相似文献