Dust and Pleistocene ice ages: Eolian sediments and climate change at Ziegler Reservoir,Snowmass Village,Colorado.

详细信息   

• 作者：Honke ; Jeffrey S.
• 学历：Master
• 年：2014
• 毕业院校：University of Denver
• Department：Geography.
• ISBN：9781321285994
• CBH：1567671
• Country：USA
• 语种：English
• FileSize：8955913
• Pages：125

文摘

The discovery of the Ziegler Reservoir fossil site near Snowmass Village,Colorado presents an opportunity to examine subalpine ecosystem response,during a relatively unknown period,in which climate conditions were similar to present. Fine-grained sediments at Ziegler Reservoir represent continuous deposition between ~140--55 ka (thousand years before present),spanning the close of the Bull Lake glacial period [marine isotope stage (MIS) 6],the Sangamon interglacial (MIS 5) and the early stages of the Pinedale (early Wisconsin) glacial period (MIS 4). Ziegler Reservoir is positioned on top of a ridge,at an elevation of 2705 m,and has a small watershed area (~14 ha),with little evidence of fluvial sediment transport. Particle size distributions,mineralogy,and geochemistry indicate eolian processes were the likely mechanism for deposition of the local,silt-rich and clay-rich sediments that ultimately filled the basin. The presence of clay-rich units (up to three-times more clay than background),is interpreted to represent glacial conditions at two distinct intervals: 1) ~140--134 ka (MIS 6) and 2) ~71--55 ka (MIS 4/3),which correspond to late Bull Lake and early Pinedale glacial periods,respectively. In addition,the absence of clay-rich sediment in the intervening sediments suggests a lack of glacial activity during sub-stages MIS 5d and 5b. In all,the Ziegler Reservoir sedimentary record provides critical information regarding environmental response of high-alpine ecosystems to climate change in the Rocky Mountains during the late Pleistocene.