中国东部沿海平原第四系层序类型

THE TYPE OF QUATERNARY SEQUENCE IN THE EAST CHINA COASTAL PLAIN

据渤海湾西岸、长江三角洲地区钻孔资料,确定在构造沉降背景下形成的中国东部沿海平原第四系见两类层序。超过0.10Ma周期的大洪泛事件,分别发生在约2.60、0.8、0.5(?)和0.15Ma前后,相当于层序地层的水进体系域,在天津北部平原系华北盆地北边缘山体周期性隆升,在长江一线是附近低山丘陵周期性隆升的表现,反映沿海平原环境变化对西部构造-气候旋回的响应。MIS5以来沿海出现受全球海面变化控制的3期10ka级海侵,结合海域研究可以确定MIS1期间出现完整的海侵-海退层序,沿海平原10ka开始的全新世沉积为高位体系域,7～10ka基底泥炭作为最大海进面,在下切河谷内可见14C测年早于10ka的泥炭。

Based on materials from the drilling holes in the west coast of Bohai Bay and the Yangtze River delta area, the present paper determined two types of sequence stratigraphy in the East China coastal plain formed under the tectonic subsidence setting. The great flooding events which had a cycle of over 0.10 Ma in the fluvial system and occurred at cir. 2.60 Ma, 0.8 Ma, 0.5 Ma （？） and 0.15 Ma respectively, could be correlated to the transgressive system tract（TST）in the sequence stratigraphy. These are related to the periodic uplifting of northern mountain in the North China basin in the north of Tianjin and to that of low mountain and hills along the Yangtze River, and all represent the response of environment in the coastal plain to the recto-climatic cycles in West China. Since MIS5 three transgressions with 10 ka period controlled by global sea-level change occurred in East China coastal plain. Combining with research results in the sea region, it can be determined that a complete transgression-regression sequence appeared in MIS1 period; in the coastal plain the Holocene transgression bed formed since 10 ka is corresponding to the parasequence in the high-stand tract （HST）. The basal peat dated 7-10 ka is the maximum flooding surface and the peat older than 10 ka in ^14C age could be found at the incised valley.