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

拉洪坦湖晚更新世历史已被深入研究了100多年。众所周知，晚更新世Labontan湖旋回只是中更新世以来几个湖旋回中最新的一个，但人们对这些湖的范围的时间知之甚少，很大程度上是因为这些旋回只被暴露较差的湖泊沉积所证明，而湖泊范围的信息有限。最近，内华达州其他晚更新世洪水湖的海岸线序列高于拉洪坦最大水位和海岸海拔，开辟了一条新的研究途径。目前，对这些海岸线的时间限制是最小的。我们建议使用宇宙成因的36c1和10Be的积累来确定这些海岸线特征的日期。建立这些湖泊周期的年表将使大盆地的古气候与全球冰川-间冰期周期的古气候进行长期比较，将有助于理解最大湖泊面积明显长期减少的原因，将有助于重建洪堡河水系的地貌完整性，并将有助于解释大流域西部和中部(目前)封闭水系中水生生物群的地理分布。

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.