Sedimentary Environmental Evolution Of The Strata During The Middle And Late Holocene In The Shijijiahe Region,Hubei Province

Middle and late Holocene is a high-speed development period of prehistoric civilization in the middle reach of the Yangtze River.It is the stop of the Old Stone Age and the beginning of the New Stone Age,since which human civilization transferred from hunting and gathering to farming civilization.It is a milestone of human civilization.The strata of Tanjialing in Shijiahe Area has the information both of palaeoenvironment and human activities.Thus the research on the strata in the area has completely profound significance.We conducted high-resolution studies on deposit from Tanjialing Site in Shijiahe Area,Hubei Province.By the data of granularity,sporopollen,magnetizability,geochemical indicators and AMS14 C,we restored the palaeoenvironment and discussed sporopollen comlex and the evolution of sedimentary environment.And we got the conclusions as follows:(1)we gathered the magnetizability and geochemical indicators of profiles in T6283 east wall and T6183 south wall of Tanjialing Site and archaeological and historical records.These data showed that social productive force in Tanjialing Area of Shijiahe Age flowered as never before.The civilization had reached a peak of prehistoric culture.(2)we concluded that the metal content in cultural layer is more than that in natural layer by the geochemical elements content and granularity from two profiles.It is a signal of metal smelting.And the content of silt,clay and sand fluctuated fiercely,which indicates that unstable sedimentary environment and human disturbance.We found a lot of walls,ditches,wooden structure,pit,foundation trench,tombs and pillar holes in Tanjialing Site.Thus we can say that human activities has a significant influence on the environment in Post Shijiahe Age,Shijiahe Age and Qujialing Age.(3)natural layers' sporopollen data in Tanjialing indicates that evergreen and deciduouos broad-leaved forest was the main types of vegetation in the region during 10100-6970 cal a BP.And there was pine forest founded in higher ground.Pollens of hydrophilic floating-leaved plants were founded all over the whole profile and the size fraction didn't have sandy size,which shows the characteristics of stable sedimentary environment,abundant rainfall and hydrostatic lake deposit.We also found a few spruce and fir of cold temperate coniferous forest.Considering it was in a warmand-wet state,we speculate that pollens of spruce and fir were carried by running water to this area.During 7870-6970 cal a BP,more companion plants were founded than other periods.That shows frequent human activities.