| 安徽五河、河北南皮Propontocypris的发现——兼论2kaB.P.的突然变化事件 |
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| 关键词:marine Ostracoda Wuhe of Anhui Nanpi of Hebei sudden change event |
| 基金项目:地质行业基金 |
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| Discovery of Propontocypris in Wuhe of Anhui and Nanpi of Hebei as well as the Discussion on Sudden Change Event at ca.2ka B.P. |
| After the discovery of Sinocytheridea impressa (Brady)( euryhaline marine ostracoda)from the Late Pleistocene strata in the Fengxian and Peixian counties at the west side of Weishanhu Lake,Jiangsu ,as well as in the Xiaoxian County of Anhui , Propontocypris euryhalina Zhao( euryhalina marine ostracoda)have been discovered from the flood land sediments at the Chongtonghe section of Wuhe County,Anhui.On the section the layer yielding this species is located above the Western Han Dynasry (206 a A.C.-24 a A.D.)cultrual layer (marked by in Fig.1),many ceramics fragments can be found in the layer.Same species also occurs at the brickfield section of Nanpi County,Hebei .In the modern environment, P.euryhalina only occurs at superlittoral zone and closed lagoon.On the Bachagou section of Fuxian County,Liaoning ,the marine ostracoda occurring at the samples of 2.80 m and 5.50 m just all being this species. Usually, once the marine microbiotas occurred,we all call it the transgression.However,the microbiotas tests can be transported upsteam from estuary,so that the transgressive effect range represents an irregular curve.At the other hand,the coastal mud yielding microbiotas “eggs”also can be transported by birds legs .The marine species also survive in the land water where Na + and Cl - are dominant .The diversity for the ostracod assemblage at Nanpi section is higher than that of the Wuhe section,this fact shows that the hydrochemical condition for the first was more complex and P.euryhaline could breed in it. The storm effect is also the reason,which caused the hudrochemical condition to be changed. Archaeologists proposed that near 2 ka B.P.a transgression had happened on the west coast of the Bohai Sea based on the hiatus in cultural relics.The history document also noted the storms at that time and the fact that sea water had submerged large coastal plain.However ,the storm is a temporal event and it is not the transgression in geological concept.We only call it the sudden change event and it was related with the change of wind field,atmospheric pressure field and extreme sea_level at the storm duration,for example that in Nanpi.Such explanation couldn't to be used in Wuhe,because we have not enough information on the height for the history storms.The black soil layer overlaying ciltural relics was the remark for ground water level had being rising .This layer represents a wet meadow environment.Except the landform factor,the increasing of storms frequency and strength,the quantitative research for the possibility of sea_level rising then should be considered. |
| TIAN Guo-qiang,WANG Qiang.1997.Discovery of Propontocypris in Wuhe of Anhui and Nanpi of Hebei as well as the Discussion on Sudden Change Event at ca.2ka B.P.[J].Acta Geoscientica Sinica,18(4):438-444. |
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