闽南沿海全新世地质年代学研究

STUDIES OF HOLOCENE GEOCHRONOLOGY IN THE COASTAL REGIONS OF SOUTHERN FUJIAN

一、前言通过沉积物的放射性碳年代测定和孢粉分析,查明晚冰期以来的气候波动、海陆变迁和沉积发育的历史,进行各种地质事件的编年和地层的划分对比,是第四纪研究尤其是全新世研究的重要内容。在我国沿海地区,全新世地质年代学研究已取得一些有意义的成果,已经建立了辽宁南部的全新世地质年代表,並对渤海湾西岸的海相地层和贝壳堤以及黄海和东海的大陆架沉积等做了年代学方面的研究。闽南沿海地区地处台湾海峡西岸,在全新世环境演化过程中留下了比较发育的全新世沉积物,其中常含有泥炭、木头、贝壳、淤泥等适于进行C14年代测定的材料,并富含孢子花粉,为全新世地质年代学研究提供了有利条件。

Our studies on radiocarbon chronology and palynology of Holocene sediments in southern Fujian along the western coast of the Taiwan Strait show that the natural environment had undergone three stages of development during the Holocene Epoch.From Early Holocene(about 10,000-8,000 years ago)to Middle Holocene(8,000-2,500 years ago)and then to Late Holocene(since 2,500 years ago),sediments varied from land-sea transitional(Gaobiantou Formation)to marine(Xulintou Formation)and then to terrigenous(Tangnei Formation).Vegetation altered from mixed forest to evergreen broadleaf forest and then to mixed forest and grassland,and climate fluctuated from mild to hot and then to warm.The earlier stage of Middle Holocene,corresponding to the Atlantic(8,000-5,000 years ago)was the climatically hottest and wettest stage in the Postglacial Period.The climatic drying and eolian sand deposit began at 700 years ago.The highest sealevel in Holocene occurred at 5,000-6,000 years ago and the transgression extent reached its maximum at 5-10 m in elevation.During the subsequent regression,there were two stable stages of sealevel dated at over 3,000 and about 2,000 years ago.