渭河盆地新生代沉积相研究  

Sedimentary facies of the Cenozoic in Weihe Basin

作　　者：李智超[1] 李文厚[1] 李永项[1] 李玉宏[2] 韩伟[2] 闻金华[1] 陈萌[1] 秦智[3] 

机构地区：[1]西北大学地质学系,陕西西安710069 [2]西安地质矿产研究所,陕西西安710054 [3]中国石油长庆油田分公司,陕西西安710018

出　　处：《古地理学报》2015年第4期529-540,共12页Journal of Palaeogeography：Chinese Edition

基　　金：国地质调查局矿产资源调查评价项目(编号:12120113040300)资助

摘　　要：渭河盆地位于鄂尔多斯地块南缘与秦岭造山带的交接部位,为一新生代盆地,古近系和新近系沉积厚度几千米,沉积类型多样,通过钻井及大量野外剖面的详细观察及实测,开展了地层、沉积相及岩相古地理学的研究。对渭河盆地新生代地层单位进行了重新厘定,并根据沉积特征划分为冲积扇沉积、河流沉积、湖泊沉积、三角洲沉积及风成沉积5种沉积类型。研究认为:整个沉积过程,盆地边断、边陷、边充填,纵向上极不对称,沉积中心偏南,平面上西窄东宽,盆地边部以冲积扇沉积为主,向中心由三角洲沉积逐渐过渡为湖相沉积。盆地从始新世开始沉积,渐新世后期抬升并存在沉积间断,中新世冷水沟期接着开始沉积,水体逐渐扩大,寇家村期湖泊广泛发育,至灞河期沉积范围达到最大,上新世游河期盆地存在西安、固市两大沉积凹陷区,边部开始出现风成沉积,第四纪西部隆起,湖泊沉积范围开始缩小,中更新世至全新世,盆地内湖泊萎缩成区域上的小型洼地。Weihe Basin is a Cenozoic basin, located in the transitional area of the southern margin of the Ordos block and the Qinling orogenic belt. The Paleogene-Neogene successions are of several kilome- ters in thickness, and of various sedimentary types. Based on drilling data and fieldwork observation andmeasurement, the stratigraphy, sedimentology and lithofacies palaeogeography of the Weihe Basin were studied. The stratigraphic units of the Cenozoic in Weihe Basin were redefined. According to the sedimenta- ry characteristics, five depositional types were distinguished in Weihe Basin, i.e., alluvial fan, fluvial, lacustrine, deltaic and eolian deposits. The results suggest that： Due to fault, subsidence and filling dur- ing the depositional process, the basin is extremely dissymmetric in profile and has the depocenter locating southerly. The basin is narrower in the west and wider in the east. Alluvial fan is predominant in the mar- ginal area, which gradually transforms into the delta and then the lake towards the center. The Weihe Ba- sin began to deposit since the Eocene. It was uplifted and had a hiatus during the Late Oligocene. During the Miocene, it restarted to deposit in the Lengshuigou Age ; as the distribution range of water body gradu- ally expanded, it widely developed lakes in the Koujiacun Age, and reached the maximum sedimentation area up to the Bahe Age. During the Pliocene Youhe Age, it formed two major depositional depressions within the basin, i. e., the Xi＇an Depression and the Gushi Depression; meantime, the eolian deposits firstly appeared at the basin margin. During the Quaternary, the western region of the basin was uplifted, and the distribution range of lakes gradually shrinked. From the Middle Pleistocene to the Holocene, the lakes shrinked into small sags locally.

关 键 词：新生代 沉积相 风成沉积 西安 渭河盆地 

分 类 号：P531[天文地球—古生物学与地层学]