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，以继续研究简单圆顶冰芯的物理和结构特性。这项工作将包括继续监测岩心松弛过程，进一步检查simple Dome岩心中保存的火山灰和尘埃记录，以及它与Byrd岩心中广泛下降的火山灰的时间和分布模式的关系，以及可能的气候影响，从800米以下额外切割薄冰，以获得更深的冰对增加变形和升高的反应的更准确的图像，并测量基底含碎片冰的总空气含量，以评估碎片在床上结合的机制。特别有趣的是，正在进行的解决简单圆顶气候记录和完善时间尺度的尝试。目前，我们正在努力利用基于目视地层学和ECM结合天然气记录的年度层数来获得最佳的深度年龄尺度。最近，来自simple Dome岩心的许多与气候相关的记录显示，在大约680米处可能有一个中断，在大约720米处可能有一个主要的气候事件。然而，简单圆顶岩心的层状结构显示出高达559 m的反向倾斜层状结构，并有证据表明在更深的冰层中存在扰动和陡倾斜层状结构。至关重要的是，我们要确定是这种结构扰动导致了气候记录的不连续性，还是其他一些没有影响记录连续性的结构人为因素。除了对岩心进行进一步的目视检查外，我们计划在几个受扰动冰结构的区域准备垂直厚切片，以确定晶体结构是否显示变形的证据。在完成这项工作之前，我们将不知道一个连续的气候记录存在于地核的多深。

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.