Physical and Structural Properties of the Siple Dome Core

该奖项支持一项为期两年的更新计划，以继续研究Siple Dome冰芯的物理和结构特性。这项工作将包括：继续监测岩芯的驰豫过程，进一步研究Siple Dome岩芯保存的火山灰和尘埃记录，及其与伯德岩心广泛下沉的时间和分布模式的关系，以及可能对气候产生的影响，对800米以下的冰进行更多薄切切片，以更准确地了解较深的冰对变形增加和温度升高的反应，并测量含碎片的底层冰的总空气含量，以评估碎片进入海床的机制。特别耐人寻味的是正在进行的解决Siple Dome的气候记录和完善时间尺度的尝试。目前，我们正在努力获得可能的最佳深度-年龄标尺，该标尺利用基于视觉地层学和ECM的年度地层计数，并结合天然气记录。最近公布的许多来自Siple Dome核心的与气候有关的记录表明，在大约680米处可能出现间歇期，在大约720米处可能发生重大气候事件。然而，Siple Dome核心的层结构显示出高达559米的反向倾斜分层，以及更深的冰中有扰动和陡峭分层的证据。至关重要的是，我们要确定这种结构性扰动是否导致了气候记录的不连续性，或者是其他一些没有影响记录连续性的结构性因素。除了对冰芯进行进一步的肉眼检查外，我们还计划在几个受干扰的冰结构区域制备垂直厚的切片，以确定晶体结构是否显示出变形的证据。在这项工作完成之前，我们将不知道在地心深处存在着多深的连续气候记录。

This award supports a 2-year renewal program to continue research on the physical and structural properties of the Siple Dome ice core. This work will include continued monitoring of the core relaxation process, additional examination of the volcanic ash and dust record preserved in the Siple Dome core and its relationship to the timing and distribution pattern of widespread infall of tephra in the Byrd core, and possible climatic implications, additional thin sectioning of ice from below 800 m to obtain a more accurate picture of the response of the deeper ice to increased deformation and elevated temperatures, and measurements of total air content in the basal debris-bearing ice to evaluate mechanisms by which debris is incorporated at the bed. Especially intriguing are ongoing attempts to resolve the climate record at Siple Dome and to refine the time scale. Currently, we are working to obtain the best possible depth-age scale that utilizes annual layer counting based on visual stratigraphy and ECM in conjunction with the gas record. Many climate-related records from the Siple Dome core have recently been presented showing a possible hiatus at approximately 680 m and a potential major climatic event at around 720 m. However, the layer structure in the Siple Dome core shows reversed inclined layering as high as 559 m and evidence of disturbed and steeply inclined layering in deeper ice. It is critical that we determine whether this kind of structural disturbance has resulted in discontinuities in the climate record or is some other structural artifact that has not impacted the continuity of the record. In addition to conducting further visual examination of the core, we plan to prepare vertical thick sections in several regions of disturbed ice structure to determine if the crystal structure reveals evidence of deformation. Until this is complete, we will not know how deep into the core a continuous climate record exists.