温州瑞安平原QTZ4孔第四纪地层及沉积环境演变

Quaternary stratigraphy and sedimentary environment evolution of the Ruian Plain in Wenzhou, China revealed by cores of hole QTZ4

温州瑞安平原东濒东海,第四纪以来沉积了较厚的海陆交互相地层,对其进行研究对于揭示浙东南沿海海陆变迁、古环境演变具有重要意义。本文以瑞安平原中部的QTZ4孔为研究对象,采集钻孔岩心样品,进行沉积物古地磁、孢粉、有孔虫及介形类等测试,并综合分析第四纪沉积特征、古环境演化过程等信息。结果表明,QTZ4孔全新统底界为45 m,上更新统底界为104.8 m,而104.8~164 m为中更新统,缺失早更新统;气候经历了从凉干逐渐到温暖湿润,又逐渐转凉、湿度减少的过程,在晚更新世末至全新世初达到最温暖湿润的状态。晚更新世早期已发生了小规模的海侵,晚更新世晚期亦可见海侵层,最大规模的海侵则发生于全新世。

The east coast of Ruian Plain in Wenzhou, China is close to the East Sea. There is a relatively thick set of Quaternary sea-land interlayer strata. The research on it is of great significance to reveal the sea-land changes and paleoenvironment evolution along the southeast coast of Zhejiang Province. Sediment samples form the core of Hole QTZ4 in the central of Ruian Plain were collected for testing their paleomagnetic, sporopolynical, foraminiferal and ostracoid indexes, and then have been comprehensively analyzed the Quaternary sedimentary characteristics and paleo-environmental evolution process of those sediments. The results show that the bottom boundaries of the Holocene, Upper Pleistocene, and Middle Pleistocene in the QTZ4 hole are at 45m, 104.8m, and 164m, respectively. There is no sediment of the Early Pleistocene. The climate was changed from cool and dry to warm and humid, and then to cool with low humidity, with the warmest and most humid state in a period from the end of Late Pleistocene to the beginning of Holocene. Small-scaled transgressions occurred in the early stage of Late Pleistocene. Transgressive sedimentary layers were also seen in the upper part of Upper Pleistocene. The largest scaled transgression occurred in the Holocene.