渤海湾北岸TZ02孔晚新生代沉积环境演化过程

渤海湾北岸晚新生代沉积环境和沉积体系不仅是区域水文地质、工程地质的基础，也为古近纪沉积模式提供“将今论古”的依据。本文依据沉积物色度和粒度，以及沉积物岩性、结构和构造等，将渤海湾北岸TZ02孔划分了6个沉积组合、4个沉积阶段：1）2.10~3.22Ma，沉积组合Ⅰ和Ⅱ，湖盆填充期，发育湖相-泛滥平原相或湖相-曲流河相，该时期处于构造稳定期，干冷气候时期发育河流相、泛滥平原相，湿润气候时期发育湖泊相。2）1.33~2.10Ma，沉积组合Ⅲ，湖盆开始发育期，主要为浅湖相，仅有少量砂体，下部多有机质，上部多钙质淀积结核，指示了盆山之间的构造分异后，湖泊初始发育的特征。3）0.62~1.33Ma，沉积组合Ⅳ，湖盆扩张期，以湖相为主，多砂体，且有短期湖泊水位变浅和成陆过程；指示了盆山构造分异后，盆地加速沉降，湖盆扩张；山体隆起、河流下切，盆地中湖相砂体增多；此时TZ02孔附近为湖相中心，BG10孔为湖泊边缘。4）0~0.62Ma，沉积组合Ⅴ和Ⅵ，湖泊填充期，BG10孔为湖相的沉积中心，而TZ02孔为湖泊的边缘，接受滦河迁移摆动后的沉积物；中更新世后，构造沉降形成湖相，而间冰期发育海相，埋深0~22.5m的海相-河流相更直接地反映了末次冰消期海平面变化过程。

SEDIMENTARY ENVIRONMENT EVOLUTION OF BOREHOLE TZ02 IN THE NORTHERN BOHAI BAY DURING LATE CENOZOIC

Northern Bohai Bay is located within the northern Huanghua Depression, which has a number of secondary tectonic units. The Cenozoic strata of the Huanghua depression are over 6000m thick:ca.3100m for the Paleogene, ca.2400m for the Neogene, and 330~490m for the Quaternary. Borehole TZ02(39°19.7'N, 119°5.3'E) is located in the southern Laoting County of Tangshan, Hebei Province, and within the Laoting sag of the Huanghua Depression, and located at the natural levee of the abandoned channel for the Luanhe River. Borehole TZ02 has a length of 550m. Based on the luminance values and redness values of sediments, and combining the sedimentary characteristics and grain size characteristics, borehole TZ02 has been divided into six stratigraphic units, and the times of these units have been dated by detail magnetostratigraphic chronology. The bottom age of borehole TZ02 is ca.3.22Ma.