青藏高原东北缘陇中盆地及周边晚新生代沉积、地貌及水系演化

The Longzhong Basin in the northeastern margin of the Tibetan Plateau, which is composed of a series of secondary Cenozoic basins and developed of typical stratified relief and continuous sedimentary basin successions, records the Tibet plateau uplift and environmental change information to which are widely pay attention by the geologists worldwide. Recently, the studies in this region have made breakthrough progress, for example, we found of more than 10 000 pieces of fauna fossils and established the late Cenozoic uplift of the Tibetan Plateau and its environmental effect theory framework which have large effect in the world. However, the evolution history of the basin, the precise time and process of the formation and change of the giant landforms along with the Yellow River drainage are still need to figure out. Besides, the relation between them, the process and driving factors of interaction within land surface system are unclear. Analysis based on meticulous chronology controlled basin sedimentary characteristics which including the palaeocurrent, source, sedimentary facies, stratigraphic thickness and spatial-temporal variation, the distribution regularity of layered landform surface composed with planation surface, erosion surface and the river terraces, combined with thermochronology research of the bedrocks surrounding the basin, to reveal the evolution history of the basin and change characteristics of the major landforms and the Yellow River drainage. Combining with the existed results of major tectonic and climatic events of this region, we try to reveal the background, process and reason of the formation and evolution of late Cenozoic paleogeography, major landforms and the Yellow River drainage, to discuss the interaction process and space-time evolution of the key elements which means water, earth, air and life in the surface system of northeast margin of the Tibetan Plateau. This study is contribute to the geomorphology theory, providing important evidences for the Tibetan plateau uplift, progress and mechanism of environment change and land surface system.

青藏高原东北缘陇中盆地由系列次级新生代盆地构成，发育典型古地貌面和较连续新生代沉积，记录着高原隆升和环境变化信息，广受国内外地学界关注。该区三十多年大量研究取得了突破性进展，发现超过1万件新生代哺乳动物化石,我们建立了晚新生代青藏高原隆升及其环境效应理论框架，在国内外产生重要影响。然而，至今盆地演化、地貌发育和黄河水系形成过程及其与高原隆升关系等重要科学问题没得到较好解决。本项目在先前研究基础上，通过精细年代控制的盆地沉积（古水流、物源和沉积相空间变化规律等）和古地貌面（夷平面、剥蚀面和阶地等）时空分布特征研究，结合周缘山体热年代学等分析，揭示陇中盆地晚新生代沉积和地貌演化及黄河水系形成过程，并与重大构造和气候事件对比，揭示该区古地理和水系形成的原因，探讨高原东北缘表层系统相互作用过程及时空演化规律，为丰富地貌学理论、深化青藏高原隆升与环境变化和陆地表层系统变化过程与机理研究提供重要证据。

本项目在前人研究基础上，针对目前青藏高原东北缘陇中盆地演化、地貌发育和黄河水系形成过程、环境演变及其与高原隆升耦合关系等方面存在的科学问题，开展了大量盆地沉积学、低温热年代学、生物磁性地层年代学、物源、层状地貌面（夷平面、剥蚀面和阶地）、西部黄土高原第四纪黄土、新近纪以来的古生态环境定量重建工作，获得了青藏高原东北缘晚新生代以来沉积-构造-水系-地貌-环境等方面较为全面的科学认识，并综合全球气候、区域构造活动等信息进行集成研究，深入探讨了晚新生代以来高原东北缘构造-地貌-气候-生态等相互耦合关系。主要认识如下：1）青藏高原东北缘陇中盆地新生代早期为统一盆地，晚中新世以来这个统一盆地逐步瓦解形成现今的次级盆地；2）确定了青藏高原东北缘主夷平面自晚中新世（8-6 Ma）开始解体，之后开始阶段性快速隆升；3）黄河水系在兰州盆地建立的时间约为3.6 Ma、黄河重要支流—大通河和渭河等现代河谷发育和水系演化始于1.4-1.1 Ma左右，且陇中盆地河流阶地序列是冰期-间冰期的气候旋回与构造抬升相互作用的结果；4）确定了西部黄土高原兰州盆地最厚（416.2 米）和最老（2.8 Ma）黄土-古土壤序列及古季风演化历史；5）多指标综合集成研究重建了青藏高原东北缘新近纪以来古生态-环境演变和亚洲内陆干旱化历史；6）综合对比高原东北缘沉积演化、构造活动、水系发育、季风演变和生态环境演变历史，发现晚中新世-上新世以来高原强烈隆升塑造了现代地貌格局，全球气候变化叠加其上共同作用。本项目所取得的研究成果不仅丰富了地貌学理论、深化了青藏高原隆升与环境变化研究，并为陆地表层系统变化过程与机理的研究提供重要证据，而且为高原东北缘“一带一路”区域未来基础设施建设以及生态恢复和环境整治提供科学依据。项目成果在国内外学术期刊上发表论文34篇（SCI论文25篇），已培养研究生12名。项目组成员参加学术会议23人次和国外访问学者3人次。