喀喇昆仑山克勒青河谷冰川冰岩界面特征的初步研究

Characteristic at Boundary Face of Ice-Bedrock on the Upper Region of Shaksgam Valley, Karakoram

It was found through the field observation at four valley glaciers, longer than 20 km in the upper Shaksgam valley, the Karakoram, that there are regelation layers, subglacial cavities at ice-rock boundary, and some englacial and subglacial shearing belts.The grain size data of the subglacial debris show that the kurtosis on the grain size frequency curves is single type. With the increasing heat and melting water at ice-rock boundary, the mean grain size, skewness values decrease, and the Matrix index and Abrasion index increase; the ratios of grain size content between two sides of 2 can show the degrees of the crushing and abrasion.The thickness of regelation layers are 20-30 cm at the bottom of terminal of Urdok and Stagar Glaciers. Melting water at ice-rock interface implies that the heat got at ice-rock boundary is larger than that translated out by ice. The analysis of debris grain size shows the grain size peak values are located area>2 at frequency curves. Underneath the terminal of Singye glacier, some ice sliding marks no melting water, but can be seen on the ice of the cavity top, suggesting the getting heat under the glacier and the heat translated out by ice be in an approximate equilibrium; the debris grain size has a peak value spot at frequency curves located at region < 2 . This result is agree with research at larger Gongba Glacier, Mt. Gong Ga. Thus, the area of subglacial debris grain size peak values located at the frequency curves is related with subglacial thermal regime, the point of 2 at frequency curves is, possibly, a critical point.