环渤海地区及华北平原第四纪古环境变迁机制

The Mechanism of Quaternary Palaeoenvironmental Change in Circum-Bohai-Sea Region and North China Plain

在青藏高原隆升背景下,环渤海地区与华北平原成为中国东部汇流盆地和堆积平原。第四纪时期阶段性河流进积,造成研究区出现构造气候旋回性的环境变迁。晚更新世以来沿海平原进入一个快速沉降阶段,在全球性冰川海平面变化叠加背景下,研究区水热对流状况以及相应的环境变迁更加剧烈和丰富。在晚全新世河流造陆过程中,河流的沉积速率超过了海平面的上升速率,陆地才得以形成。在现代海岸带依然持续构造沉降、河流输沙减少、相对海平面上升的背景下,认识不同时间尺度环境变迁机制是极其必要的。

Under the Tibet-Qinghai Plateau rising setting, the Circum-Bohai-Sea (CBS) region and North China Plain became a confluence basin and accumulation plain since Quaternary, and the periodic river progradation caused the happening of palaeoenvironmental change with tectono-climatic cycles characteristic in the CBS region and North China Plain. Since the Late Pleistocene the coastal plain subsidence came into a quick phase, because the global eustasy superposed, as a result, the hydrothermal situation and relative environment change into more abundant and acute. Since the late Holocene in the process of modern land forming, the sediment accumulation rate is over that of sea level rise, the land formed finally. Today on the coast zone, there still is continuously tectonic subsidence but the river loading reduces, which results in the sea level rises relatively. It is very necessary to know the mechanism with different time-scale for palaeoenvironmental change.