长江三角洲平原南部上新世以来古环境演变及多重地层划分

对长江三角洲平原BZK01钻孔进行沉积物¹⁴C测年、粒度、磁学、孢粉和微体古生物分析，结合伽玛测井、岩性地层讨论了上新世以来钻孔揭示的孢粉组合、沉积环境演化、沉积相和古气候特征，建立了钻孔的第四纪多重地层划分对比框架。结果表明，受原始地形地貌、海平面变化、海陆变迁、古气候冷暖更替及新构造运动的影响，研究区上新世以来经历了多次环境变化。钻孔自下而上揭示岩性地层依次为基岩长河组、新近纪-第四纪沉积的嘉兴组、前港组、东浦组、宁波组、镇海组，孢粉组合可划分出16个孢粉带，按暖期温暖潮湿-冷期寒冷干燥古气候旋回变化的周期律，BZK01钻孔反映该区域共存在7个古气候旋回。建立的钻孔多重地层划分对比揭示151.9～278.0 m为河流相和河湖相交替沉积的上新世-早更新世时期，存在两个气候旋回过程；83.5～151.9 m为河流相-河湖相-浅湖相沉积环境的中更新世，包含两个气候旋回过程；15.4～83.5 m为晚更新世，沉积环境自下而上为河口相-河湖相-潮坪相-滨海相-河湖相，与王店海侵-杭州海侵时期对应，包括两个气候旋回；0～15.4 m为河口相-河湖相-泻湖相沉积环境的全新世，对应富阳海侵，包括一个气候旋回。

Stratigraphic Division and Paleoenvironment Evolution in the Southern Yangtze River Delta Plain since the Pliocene

In this paper, the systematical study of ¹⁴C dating, granularity, magnetism, sporopollen and micropaleontology in sediments of the BZK01 bore in the Yangtze River delta plain was conducted, characteristics of sporopollen assemblage, sedimentary environment evolution, sedimentary facies and paleoclimate changes recorded by the bore sediments was combined with gamma-ray logging and lithostratigraphy to discuss and to establish the framework for the Quaternary multi-stratigraphic division in the study area. The results showed that, due to influences of primitive landform, sea level change, sea-land transformations, paleoclimatic replacements of cold-warm and neotectonic movements, the study area had experienced many environmental changes since the Pliocene. The lithostratigraphic assemblages of the core from bottom to up is Changhe formation, Jiaxing formation, Qiangang formation, Dongpu formation, Ningbo formation and Zhenhai formation, respectively, while the sporopollen assemblage can be divided into 16 sporopollen belts. According to the periodic law of the paleoclimate cycle of warm-humid to cold-dry, the BZK01 bore recorded 7 paleoclimatic cycles of the region. The established multilayer stratigraphic divisions in the bore and their correlations revealed that the stratum of 151.9-278.0 m represented the early Pleistocene period of fluvial facies and fluvial and lacustrine facies, two climatic cycles were identified during this period; the stratum of 83.5-151.9 m represented the middle Pleistocene with the environment of fluvial, lacustrine and shallow lacustrine sedimentary, two climatic cycles were identified during this period; the stratum of 15.4-83.5 m represented the late Pleistocene with sedimentary environments of estuarine facies, lacustrine facies, tidal flat facies, coastal facies and riverside facies, corresponding to the transgression period of Wangdian to Hangzhou, two climatic cycles were also identified during this period; the stratum of 0-15.4 m represented the Holocene with environments of estuarine, fluvial and lagoon facies sedimentary environment, corresponding to the Fuyang transgression, one climatic cycle was identified during this period.