祁连山及邻区第四纪地层区划与沉积序列

在前人资料和野外勘查的基础上对祁连山及邻区贵德盆地、循化—化隆盆地、同仁盆地、西宁盆地、门源盆地、临夏盆地、兰州盆地、定西盆地、天水盆地、肃北盆地、酒泉盆地、玉门盆地、张掖盆地、武威盆地、哈拉湖盆地、苏里盆地、木里盆地、民和盆地、共和盆地、青海湖盆地及柴达木等20余个盆地的第四纪地层进行了研究。以祁连山第四纪构造地貌演化、盆地沉积序列、古生物及古气候特征为地层分区依据,对祁连山及邻区第四纪地层进行了地层分区,并对部分地层名称做了厘定或统一。祁连山及邻区第四纪沉积特征总体为东部(主要为陇中地区)黄土分布广泛,堆积了世界上最厚的黄土地层;北部(河西走廊地区)冲洪积扇堆积及风沙发育;南部(柴北盆地)以冲洪积-湖积为主,晚更新世以来发育风成沙及黄土;共和盆地由湖泊转向冲积扇和风沙沉积;青海湖盆延续至今;中西部高山及山间盆地冰碛、冰水堆积以及河流阶地堆积发育。根据上述特征及划分原则,将祁连山及邻区第四纪地层区划分为:兰州—西宁地层区,贵德地层区,酒泉—张掖地层区,柴北地层区,共和地层区,青海湖地层区及肃北—门源地层区。

Quaternary stratigraphic realm and sedimentary sequence of the Qilian Mountain and adjacent areas

The Quaternary stratigraphy of twenty basins in Qilianshan Mountain and adjacent areas includes Guide Basin, Xunhua- Hualong Basin, Tongren Basin, Xining Basin, Menyuan Basin,Linxia Baisin, Lanzhou Basin, Dingxi Basin, Tianshui Basin,Subei Basin, Jiuquan Basin, Yumen Basin, Zhangye Basin, Wuwei Basin, Har Lake Basin, Suli Basin, Muli Basin, Minhe Basin, Gonghe Basin, Qinghai Lake Basin and Qaidam (N) Basin. The authors studied these basins based on the previous data and field investigations. Characteristics of Quaternary tectonic landform evolution, sedimentary sequence of basins, palaeontology and paleoclimate were used as the basis to make stratigraghic division and also to unify the name of parts of sequences. The general characteristics of Quaternary sedimentation of the study areas are as follows: Loess is widely distributed in the east (central Gansu Province) with the thickest loess in the world. Alluvial fan and aeolian deposits are distributed in the north (Gansu Corridor). Pluvial-alluvial and lacustrine deposits are distributed in the south (north Qaidam Basin), followed by aeolian sand and loess of late Pleistocene. The transition from lake to alluvial and aeolian deposits happened at the Gonghe Basin. Qinghai Lake has lasted for a long time. Moraines, pro-glacial and river terrace are distributed in the high mountains in the middle and west. According to the above characteristics and principles, the sedimentary sequences of Qilian Mountain and adjacent areas are divided into the following realms: Lanzhou- Xining stratigraphic realm, Guide stratigraphic realm, Jiuquan- Zhanagye stratigraphic realm, North Qaidam Basin stratigraphic realm, Gonghe stratigraphic realm, Qinghai Lake stratigraphic realm and Subei-Menyuan stratigraphic realm.