中国沙漠 ›› 1989, Vol. 9 ›› Issue (4): 8-18.

• 论文 • 上一篇    下一篇


李从先, 陈刚, 杨红君   

  1. 同济大学海洋地质系
  • 出版日期:1989-12-20 发布日期:1989-12-20
  • 基金资助:

Eolian Deposits in Coastal Zones of Fujian Province

Li Congxian, Chen Gang, Yang Hangjun   

  1. Marine Geology Department of Tongji University
  • Online:1989-12-20 Published:1989-12-20

摘要: 福建沿岸多处发育现代海岸风成沉积, 采用现代风砂所总结的特征作为识别标志, 研究了3000-4000年前产生的某些生物碎屑岩和3-4万年前开始形成并广泛分布的老红砂, 证明它们皆为风成, 因此晚更新世以来这里就具有风成沉积发育的条件。海岸风成沉积大规模发育出现在高海面之时, 分布也不遵循地带性规律, 这些均与沙漠地区的风砂不同。

Abstract: Eolian deposits, widely developed in the coastal zones from Fuzhou to Dongshan Island of Fujian Province, may be grouped into modern eolian sand, bioclastic rocks formed in 3000-4000 years BP and old red sand created at 30000-40000 years BP. The modern eolian coastal sands are accumulated in the form of coastal dune, sand sheet and sand lying on the slopes of hills, each of which possesses a distinct sediment tary structure assemblege. The coastal dunes are characterized by more complicated assemblege of stratifications, including high-angle and low-angle cross beddings, wedge and horizontal beddings.The sand sheet mainly contains horizotal beddings.The sand lying on the slope of hill is predominanted by low-angle cross beddings on toe of slope and high-angle cross beddings on steep part of slope near hills.The characteristics obtained from, study of modern coastal eolian deposits can be served for criteria for recognition of ancient analogue. The bioclastic rocks, represented by that in Houshijing of Pulian County, are marked by uniform grain size, with fraction of 0.5-2.0mm of 86.9-95.2% in bioclastics and 0.25-1.0mm of 73.6-86.1% in terri-genons elastics. Modern eolian deposits, with the same grain size of bio-and terrigenous elastics as that in Houshi jing.are distributed on the top of the hill with the same hight, lccated scawfids from the Houshijing's bicrlaslic rocks. The common stratifications are the wedge and divergent ones, typical for modern eolian deposits in Fujian. Judging from the characteristics of some bioclastic rocks of Fujian, they should be eolianite. The old red sand consists of fine-medium and coarsemedium sand, with small amount of mud. They are marked by massive or well-developed stratifications, in which lowangle cross beddings dominante , along with high-angle ones, Iron pan and breccia layers-regarded as bonding surface, and peat and dark grey muddy layers considered as inter-dune deposit are well developed in old red sand. Moreover, the old red sand is usually accompanied by modern coastal eolian deposit, for example the sand layers in Qinfen of Pingtan County, ranging from the old red sand to modern eolian deposit might be subdivited into several phases according to lithology, colour, consolidation and bounding surface. All of these charact-eristics demonstrate the old red sand is of eolian deposit.Some phenomena coflicting with the eolian genesis, such as content of muddy material and foraminifera, have been explained by weathering of feldsoar and sediment source being old beach sand respectively. Consequently, there exist conditions for accumulation of eolian deposits along the coastal zones of Fujian since Late Pleistocene and flourished in period of high-standing of sea level, nowaday and 30000-40000 years BP. because of abundant beach material. This is quite different from desert, where active development of eolian sand is directly related to climate, especially to annual precipitations.