Pleistocene Sea-Level and Glacial Fluctuations, Coastal Ahklun Mountains, Southwest Alaska

最近在阿拉斯加西海岸南部（布里斯托湾东部，北纬59度）的研究表明，冰川在更新世晚期经历了广泛的前进。 另一方面，在阿拉斯加西北部（苏厄德半岛，北纬65度，布鲁克斯山脉西部，北纬67度），早期威斯康星州冰川仅限于最高的山谷，所占面积比中更新世和早更新世的进展大约小一个数量级。 最近一次冰川向阿拉斯加西南部海岸的主要推进比阿拉斯加西北部海岸的最后一次推进至少年轻30万年。 为了理解这种明显的冰川地质和古气候不协调的原因和意义，必须解决以下问题：（1）在哪里和沿着海岸之间的东布里斯托湾和苏厄德半岛的距离是什么样的交叉晚更新世冰川最大和中更新世最大发生？(2)在何种程度上，山谷高程控制冰的范围从不同的来源地区？ (3)威斯康星州晚期和前威斯康星州晚期冰的地理分布对平衡线高度（ELA）降低和平衡线高度（ELA）梯度，以及由此产生的水分来源和其他气候变量意味着什么？ 要解决这些问题，需要在布里斯托湾东部和苏厄德半岛之间唯一的冰川地区--阿克伦山脉进行广泛的实地、航空摄影和地质年代学研究。 这将取决于多学科的努力，以获得对矿床的数字年龄控制。 将采用最先进的地质年代学和沉积学技术来重建更新世海平面和冰川波动的空间和时间模式。 这项工作将提高整个阿拉斯加西部的冰川作用及其与全球气候系统的关系的古气候控制的理解，应该能够解决是否在阿拉斯加西南部的冰川作用是同步的北方半球冰盖的波动，或者是否在这里的主要冰川在低纬度的冰积累之前。

Recent work in the south part of the west coast of Alaska (eastern Bristol Bay, 59oN) demonstrates that glaciers experienced extensive advances during the late Pleistocene. In northwestern Alaska (Seward Peninsula, 65oN, and western Brooks Range, 67oN), on the other hand, early Wisconsin glaciers were restricted to the highest mountain valleys and occupied an area approximately an order of magnitude less extensive than during middle and early Pleistocene advances. The most-recent major advance of glacier ice to the coast in southwestern Alaska was at least 300,000 yr younger than the last advance of ice to the coast in northwestern Alaska. To understand the cause and significance of this apparent glacial- geologic and paleoclimatological incongruity, the following must be addressed: (1) Where and over what distance along the coast between eastern Bristol Bay and Seward Peninsula does the cross-over between late Pleistocene glacial maxima and middle Pleistocene maxima occur? (2) To what extent to valley hypsometries control the extent of ice from the different source areas? (3) What does the geographic distribution of late-Wisconsin and pre-late-Wisconsin ice imply about equilibrium line altitude (ELA) lowering and equilibrium line altitude (ELA) gradients, and consequently, moisture sources and other climate variables? Solving these questions will require extensive field, aerial photographic, and geochronologic research in the only glaciated region between eastern Bristol Bay and Seward Peninsula-the Ahklun Mountains. It will depend on a multi-disciplinary effort to obtain numerical-age control on the deposits. State-of-the-art geochronologic and sedimentologic techniques will be applied to reconstruct the spatial and temporal pattern of Pleistocene sea-level and glacier fluctuations. This work will improve the understanding of the paleoclimatological controls of glaciation across western Alaska and their relation to the global climate system; should enable to address whether gl aciation in southwestern Alaska is synchronous with Northern Hemispheric ice-sheet fluctuations, or whether major glaciations here precedes ice build-up at lower latitude.