Deglacial Chronology of the Northern Scott Coast from Relative Sea-Level Curves

9909104霍尔该奖项为一个项目提供三年的支持，该项目旨在开发自上一次冰盛期(LGM)以来罗斯海西北部海湾(斯科特海岸北部)地面冰的放射性碳年代学。南极冰川学中一个尚未解决的关键问题是海基西南极冰盖(WAIS)的稳定性。要洞察现在和未来的稳定性，一种方法是检查它过去的行为。特别是，从大陆架上的LGM位置开始冰川消退的时间对于隔离控制WAIS动态的机制(海平面、气候、海洋温度和内部动力学)至关重要。斯科特海岸北部可能是第一个没有接地冰的地区，因此对隔离触发机制至关重要。从罗斯海海湾的最初撤退被认为早在17,000年前就开始了；与巴巴多斯珊瑚记录中所见的海平面上升相对应。相比之下，最近斯科特海岸南部的冰川地质测绘和相对海平面工作表明，罗斯湾的冰川消融是一次全新世事件，在6500年前不久，陆线向南迁徙通过罗斯岛。这一年表表明，海平面上升不可能促使基准线撤退到西伯利亚海岸，因为消冰期海平面上升基本上是在全新世中期完成的。斯科特海岸南部工作的一个不足之处是，它无法区分启动撤退的可能触发机制，因为它距离LGM接地线位置450公里。在这个项目中，相对海平面(RSL)曲线将在斯科特海岸北部的一条横断面上由加速器质谱仪14C测得海豹皮肤和贝壳在凸起的海滩内的日期。这些曲线将提供有关从罗斯海西北部海湾上传地面冰的时间的信息。这项研究应该有助于评估那些可能引发冰川消融并因此控制西南极冰盖(WAIS)范围的因素。

9909104 HallThis award provides support for three years for a project to develop a radiocarbon chronology for recession of grounded ice from the northwestern Ross Sea Embayment (northern Scott Coast) since the Last Glacial Maximum (LGM). A key unresolved question in Antarctic glaciology concerns the stability of the marine-based West Antarctic ice sheet (WAIS). One way to gain insight into present and future stability is to examine its past behavior. In particular, the timing of deglaciation from the LGM position on the continental shelf is critical for isolating the mechanisms (sea level, climate, ocean temperature, and internal dynamics) that control WAIS dynamics. The northern Scott Coast was likely the first area to become free of grounded ice and hence is critical for isolating triggering mechanisms. Initial retreat from the Ross Sea Embayment was thought to have begun as early as 17,000 years ago; corresponding to the rise in sea level see in the Barbados coral record. In contrast, recent glacial geologic mapping and relative sea-level work from the southern Scott Coast suggests that deglaciation of the Ross Sea Embayment was a Holocene event, with southward grounding-line migration past Ross Island shortly before 6500 14C yr. B.P. This chronology suggests that rising sea level could not have driven grounding-line retreat to the Siple Coast, because deglacial sea-level rise essentially was accomplished by mid-Holocene. One deficiency in the southern Scott Coast work is that it cannot differentiate among the possible triggering mechanisms that initiated retreat because it is 450 km from the LGM grounding-line position. In this project, relative sea level (RSL) curves will be constructed on a transect along the northern Scott Coast from accelerator mass spectrometer 14C dates of seal skin and shells within raised beaches. These curves will provide information concerning the timing of the uploading of grounded ice from the northwestern Ross Sea Embayment. This study should help to evaluate those factors which could have triggered deglaciation and hence controlled the extent of the West Antarctic ice sheet (WAIS).