Cosmogenic Dating of Old, High Pluvial Shorelines in the Western Great Basin

Lahontan湖晚更新世的历史已经被深入研究了100多年。众所周知，晚更新世拉邦坦湖旋回只是自中更新世以来几个湖泊旋回中最近的一个，但对这些湖泊的范围时间知之甚少，这在很大程度上是因为这些旋回仅由暴露不良的湖泊沉积物证明，对湖泊范围的信息有限。最近，在内华达州拉洪坦最高水平面和其他晚更新世洪积湖的海岸海拔之上发现了一系列的海岸线序列，开辟了一条新的研究途径。这些海岸线的时间限制目前是最小的。我们建议使用宇宙成因36C1和10Be的积累来确定这些海岸线特征的年代。建立这些湖泊旋回的年代学将使大盆地的古气候与全球冰期-间冰期旋回的古气候进行长期比较，将有助于理解最大湖泊面积长期明显减少的原因，将有助于重建洪堡河系统的地貌整合，并将有助于解释大盆地西部和中部（目前）封闭排水系统中水生生物的地理分布。

0001063Phillips The late Pleistocene history of Lake Lahontan has been intensively studied for over 100 years. It is well known that the late Pleistocene Labontan lake cycle is only the most recent of several lake cycles since the mid Pleistocene, but very little is known about the timing of extent of these lakes, in large part because these cycles have been evidenced only by poorly exposed lacustrine sediments that yielded limited information on lacustrine extent. A new avenue of research as recently been opened by the discovery of sequences of shorelines above the Lahontan maximum level and above the shore elevations of other late Pleistocene pluvial lakes in Nevada. Chronological constraints on these shorelines are presently minimal. We propose to date these shoreline features using the accumulation of cosmogenic 36C1 and 10Be. Establishing a chronology of these lake cycles will enable a long-term comparison of paleoclimate in the Great Basin with that of global glacial-interglacial cycles, will aid in understanding the origin of the apparent long-term decrease in maximum lake extent, will help to reconstruct the geomorphic integration of the Humboldt River system, and will contribute to explaining the geographical distribution of aquatic biota in the (presently) closed drainages of the western and central Great Basin.