LIN Zhongyang1,4, JIN Xianglong1,2, GUAN Minlin3, PAN Shaojun4, ZHAO Xudong4
(1.College of Marine Science and Technology, China University of Geosciences, Wuhan 430074, China;
2.The Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China;
3. Hangzhou Research Institute of China Coal Technology & Engineering Group，Hangzhou 311201, China;
4.Zhejiang Institute of Geological Survey, Hangzhou 311203, China)
Abstract: 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 15.4-83.5m 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 0-15.4m 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.
Keywords: Yangtze River delta plain；Quaternary period；Sedimentary facies；Paleo-environmental；Multiple stratigraphic divisions
EARTH AND ENVIRONMENT Vol.47, No.4, Tot No.330, 2019, Page 464-476