甘肃省党河地区的新生代地层和青藏高原隆升

CENOZOIC STRATIGRAPHY IN DANGHE AREA, GANSU PROVINCE, AND UPLIFT OF TIBETAN PLATEAU

甘肃省党河流域是亚洲渐新统的经典地区之一 ,但长期以来人们对这一地区的地层层序和时代的认识并不清楚 ,命名也很混乱。我们的考察表明该地区新生代地层包括渐新统狍牛泉组 (新建组 ) ,中新统铁匠沟组 (新建组 ) ,中新统—上新统和更新统四套 ;产有代表三个不同时代的哺乳动物群 :早渐新世晚期叮沟、晚渐新世燕丹图和早中新世西水沟三个哺乳动物群。该地区的岩性和地质构造表明 。

The Danghe area, located in the western most part of the Gansu Province, is southerly bordered by the Tibetan Plateau. It is one of the classic areas in the Asian Paleogene biostratigraphy. Early in the 1930s Bohlin explored this area and collected plenty of mammalian fossils. However, he did not further subdivide the strata he surveyed, nor did he name the strata or give clear indication of the fossil levels. The main reason of his hesitation was the extremely complex tectonic structure of the area (Bohlin, 1937, 1942, 1945, 1946, 1960). Since the 1950s the Danghe strata have been variously assigned to formations founded in the Yumen Basin more than 200 km to the northeast, such as Huoshaogou, Baiyanghe, Shulehe formations and Yumen Gravels. However, no detailed lithologic comparison between the Danghe area and Yumen Basin has ever been carried out. Furthermore, the stratigraphic position of Bohlin's fossils has never been satisfactorily clarified. Since the 1990s when the Tibetan Plateau became an area of intense studies, the Danghe area has gained worldwide attention among geologists. Tectonic and paleomagnetic study has been conducted there. Unfortunately, all these endeavors were based on outdated or wrong stratigraphic data (Wang, 1997; Guo and Xiang, 1998; Gilder at al., 2001, Van de Woerd et al., 2001).\;In 1999 and 2001, a joint team of the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences (IVPP), the Cultural Relic Archaeology Institute of Gansu and the Gansu Provincial Museum made geologic survey of the Danghe area. As a result, a number of stratigraphic problems were clarified based primarily on new interpretation of the rock sequences and the newly found mammalian fossils.\;