塔吉克斯坦南部黄土沉积

帕米尔高原以西的中亚黄土主要分布在帕米尔和天山的山前地带，其中以塔吉克斯坦南部的黄土分布最广。该地黄土的厚度最大可达１８０～２００ｍ，其底界年龄在２．０Ｍａ左右。野外地层观察表明，塔吉克斯坦黄土与中国黄土具有较好的一致性。塔吉克斯坦黄土来自卡拉库姆等沙漠，该地具地中海型气候条件，且搬运黄土的风力系统与中国黄土不同，而两地黄土地层则有较高的可对比性，这似乎意味着第四纪时期亚洲中纬度干旱区气候变化受某个共同的因子所制约。

A BRIEF INTRODUCTION OF LOESS DEPOSITS IN SOUTHERN TADJIKISTAN

Loess is sporadically distributed in the piedmonts of the western side of the Pamir Plateau and Tianshan mountains, but it coherently mantles a large--scale area in the southern Tadjik depression. Under the guidance of Professor Vadim A. Ranov from the Tadjikistan Academy of Sciences, we recently conducted a short expedition of the loess area in southern Tadjikistan and sampled systematically a long loess section at Chashmanigar. As laboratory work is still on the way, here we will focus our introduction only on the stratigraphy of the Chashmanigar section and the correlation between Chinese and Tadjik loess successions. Field observations show that the Chashmanigar section has a thickness of about 180m, with over 30 paleosol complexes. Paleomagnetic studies of Dodonov and others demonstrated that this section has a basal age of about 2.OMa, with the Olduvai subchron occurres near the base and the Brunhes/Matuyama boundary between the PC9 and PC10. The paleosol complexes in the Brunhes chron are separated by thick loess layers, whereas the paleosols below the B/M boundary are closely spaced. This characteristic is similar to that of the Chinese loess. The similarity between the two loess regions is also manifested by the fact that each of the loess-soil units of the Brunhes chron in the Loess Plateau can be correlated with that in southern Tadjikistan, implying a common factor driving climatic variations of the two regions.