阿尔泰山“东山区”的古冰川作用与砂金矿

Paleoglaciation and Gold Placer in East Mountains Region in Altai Mountains

Altai Mts, known as Gold Mountain, lies in northern margin of Xinjiang Region. Influenced by cold climate in Quaternary, glaciers had been widely developed at this area. In the zonations of middle and high mountains, paleoglacial vestiges well remained. Studies of paleoglacial vestiges show that there were at least three glacial stages during pleistocene. The scale of glaciation culminated in the middle pleistocene. The intense paleoglaciation had not only modeled various landforms, but also created favourable conditions of gold placer formation. First, the paleoglaciation broke down geological mass containing golds and produced tremendous rock fragments. Secondly, the paleoglaciation destroyed the stability of the residuum, accelerating weathering speed to release the gold from parent rocks. Thirdly, the glacial abrasion could grind parent rocks. These processes made gold grains isolate. At the same time, a large amounts of fine gold grains were available as crystal nucleus for chemical deposition of gold. In the paleoglaciation area of Altai Mts there are many glod placers. "East Mountain Region" is a concentrated region of moraine gold placer. According to time of the formation, three types of the gold placer can be divided in this region, they are: the pre-glacial period, the glacial period and the past-glacial period.