The Use Of Foraminifera Precision Changes In Sea Level Scale

The emphasis of sea-level changes study is to search high accurate indicator.While the traditional indicators, including coastal physiognomy and coastal sediment stratum, have shown large range of error. From the last 70's on, some distinct foraminifera assemblages, such as Jadammina macresens and Trochammina inflate, which dwelled coastal tidal salt-marsh, have been discovered in Severn, England and east coastline of the American. These assemblages are restricted between small ranges of altitude.While the peer has not been found in the southern Yellow Sea, China. The possible reason is: first of all, the anthropological reclamation impact; secondly, the global distribution of benthic foraminifera is inconsistent, and the lastly, foraminifera being collected into cluster. And so the sea-level indicator based on such few foraminifera species is inadequate.Eco-index, simple diversity or composite diversity, is the indicator of community diversity. It reflects the global characteristics of a community by digit, and is independent with specific foraminifera. Furthermore, there is corresponding relation between eco-indexes environmental factors.A total of 94 surficial sediment samples from ten sections in salt tidal marsh, located from the former estuary of the yellow river to the Luchao harbor in Shanghai, were qualitatively and quantitatively analyzed for their foraminifer's contents. The fauna and taphocoenose were analyzed separately. Use open source soft (OSS) MySQL to create a salt marsh foraminifer's database. All the eco-index, dominance, simple diversity, a index (i.e. Fisher index), information function etc, were calculated according to the database. Then combine the eco-index values and altitude value acquiring by survey on the spot. Synthesizing foraminifer's characteristic of 10 sections, the following conclusions were drawn:Micropaleobiological analyses conclusion: three foraminifera assemblages were classified, A I , 374~320cm(wusong Elevation system, 2001 the following is the same), the dominant species is Ammonia beccarii vars. and Cribrononion porisuturalis and Pseudoeponides nakazatoensis; AII, 320cm~275cm, Trochammina squamata and Miliamminafusca, AIII, 275~225cm, Ammonia beccarii vars. and Cribrononion porisuturalis and Pseudoeponides japonicus. Eco-index analyses conclusion: although there are some inconsistent between threeeco-indexes, they show the same characteristics as following:1) Diversities of fauna bigger than that of taphocoenose;2) Diversities of fauna get extremum at low-tide line and high-tide line;3) Trends of diversities in taphocoenose is complicated than that of fauna;4) Information function of taphocoenose is bigger than that of fauna.