2012 Volume 121 Issue 2 Pages 235-251
The upper Wangfeng moraine, located in the upper Urmuqi River valley, the Tianshan Mountains, China, is a cluster of hummocky moraines composed of sediments with complex lithofacies and structures (sedimentary sequence). The sediments of the Wangfeng moraine are well exposed along a road-side outcrop extending more than 500 m, and are composed of the following three lithofacies associations (LFAs). 1) Supraglacial till, diamicton with large boulders and consolidated fine matrix of higher clay content, lying at the lower half of the outcrop. 2) Supraglacial debris, and landslide and debris flow deposits from the valley slopes covering the supraglacial till. There are patches of diamictons composed of smaller boulders and sandy matrix in small parts. 3) Stratified sediments on the outer slopes of marginal moraines. At many points the bedding is inclined, dipping upstream as well as downstream; therefore, the sediments were constructed by debris flows from the glacier surface and fluvial processes. This LFA includes sediments derived from the valley side slopes by various processes. They cover the supraglacial till and occupy a large part of the outcrop. The lithfacies structures and sequence of the whole outcrop indicate that the moraine is separated into two parts: one comprises marginal moraines constructed by the main valley glacier and the other by the tributary glacier from the Qionsaersayi glaciated valley. OSL dating of fine-grained quartz shows that the supraglacial till constituting a frontal moraine at the upstream end was deposited during the global Last Glacial Maximum, and that the fluvial and debris flow sediments covering the frontal moraine from the Qionsaersayi glaciated valley were deposited during the late glacial period.
