On the Origin of Stratified Debris in Ice Cores from the Bottom of the Antarctic Ice Sheet
On the Origin of Stratified Debris in Ice Cores from the Bottom of the Antarctic Ice Sheet
复制标题
南极冰盖底部冰芯层状碎片的起源
DOI：
10.3189/s0022143000029828
复制
发表时间：
1979
影响因子：
3.4
通讯作者：
W. Sheehy
中科院分区：
文献类型：
--
作者：
A. Gow;S. Epstein;W. Sheehy
在南极伯德站冰盖底部4.83米的岩芯中，含有大量的从粉砂到卵石的分层碎屑。这些碎片的性质和分布情况，以及对封闭冰的物理特性的测量结果表明，这一充满灰尘的冰区是由冰盖底部的“冻结”造成的。从富含空气的冰川冰到几乎没有空气的冰的转变正好与冰床上方4.83米处的冰中首次出现碎片相吻合。结合气体含量测量进行的稳定同位素研究也证实了通过在冰-岩界面处的融水的冻结来并入基底碎屑的想法。据认为，基冰中不存在空气很可能是区分融冰-再冻结过程中所含碎片和纯机械手段（如剪切）所截留碎片的最佳诊断试验。我们的结论是从我们的观察底部芯从伯德站，“冻结”的基础碎片是沉积物被纳入极地冰盖的主要机制。
Abstract Cores from the bottom 4.83 m of the Antarctic ice sheet at Byrd Station contain abundant stratified debris ranging from silt-sized particles to cobbles. The nature and disposition of the debris, together with measurements of the physical properties of the inclosing ice, indicate that this zone of dirt-laden ice originated by “freezing-in” at the base of the ice sheet. The transition from air-rich glacial ice to ice practically devoid of air coincided precisely with the first appearance of debris in the ice at 4.83 m above the bed. Stable-isotope studies made in conjunction with gas-content measurements also confirm the idea of incorporation of basal debris by adfreezing of melt water at the ice―rock interface. It is suggested that the absence of air from basal ice may well constitute the most diagnostic test for discriminating between debris incorporated in a melt―refreeze process and debris entrapped by purely mechanical means, e.g. shearing. We conclude from our observations on bottom cores from Byrd Station that “freezing-in” of basal debris is the major mechanism by which sediment is incorporated into polar ice sheets.