河南省内黄县三杨庄全新世以来的孢粉学记录被引量：11

HOLOCENE POLLEN RECORD OF THE SANYANGZHUANG SITE IN NEIHUANG COUNTY,HENAN PROVINCE

导出

摘要河南省安阳市内黄县三杨庄汉代遗址地层年代跨度从更新世晚期延续至今，多次的洪水泛滥和古土壤发育形成了三杨庄地层中洪积层与古土壤层的交替出现，距地表850～212cm处包含了5个洪积层和5个古土壤层。孢粉分析结果表明：三杨庄地区10200～7200cal．aB．P．期间孢粉浓度较低，气候较为暖湿；7200～4500cal．aB．P．期间孢粉浓度显著升高，进入全新世大暖期；4500～2000cal．aB．P．期间气候向降温变干的趋势发展，但仍比较温暖。洪积层和古土壤层的孢粉组合差异主要表现为洪积层中木本植物花粉（主要为松属）含量显著高于临近的古土壤层，而且人类活动强度越大，这种差距越明显。依据孢粉组合也能较好地划分本区地层中的洪积层和古土壤层。全新世早期该区可能已经有人类从事农业活动，之后虽然遭受多次洪水侵袭，但人类活动并未消失，大致在中全新世晚期之后（约6000cal．aB．P．），人类活动强度不断增强。 Sanyangzhuang profile （35°43＇39.12＂N, 114°46＇24.22＂E; elevation 57m ） located in the north of Sanyangzhuang village in Neihuang County, Henan Province. It was close to the Sanyangzhuang archaeological site which was deeply buried by the Yellow River alluvium and maintained the original status of the Han period village. The strata in this area consist of several paleosol layers and palaeoflood sedimentary layers. The stratigraphie sequences of Sanyangzhuang profile are continuous without obvious hiatus,and ten sedimentary layers included five paleosol layers and five palaeoflood sedimentary layers were identified. The profile was dated from the beginning of the Early Holocene to Han Dynasty according to AMSX4C dating results and archaeological dates. In order to understand the environment evolution process and find the relationship between palaeoflood and pollen assemblage in this area. Samples from 850 -212cm below the surface were collected for pollen analysis. In total,89 pollen taxa were identified in 160 pollen samples that were taken from Sanyangzhuang profile with 2 -8em intervals. Based on the results of pollen analysis, the process of the change of vegetation and climate in Sanyangzhuang area can be divided into three periods： 10200 -7200cal. aB. P., the climate became warm, and the precipitation increased after the Younger Dryas Event, the paleovegetation was coniferous and broad-leaved mixed forest and grassland; During the period of 7200 -4500cal. aB. P.,the pollen concentration and broad-leaved pollen percentage increased significantly, along with the sub-tropical evergreen pollen taxa appeared, such as Platycarya and Rhus. The pollen assemblages indicated warmer climate and higher precipitation which was characters of the Megathermal in Holocene; 4500 -2000cal. aB. P., some pollen types such as Pieca and Nitraria appeared frequently, at the same time, the broadleaved pollen percentages decreased, the results showed that the climate had a trend of turning cold and aridity. Through a comparative research on the percentages of arboreal pollen of paleosol layers and palaeoflood sedimentary layers,it is clearly to discover that the arboreal pollen percentages of palaeoflood sedmentary layers were higher than paleosol layers in common. The reasons maybe mainly related to three factors： pollen source, grading function of river and human activity. The disparity of arboreal pollen percentages will be expanded especially when the pollen assemblages of paleosol layers were disturbed by some kind of human activities. The strata in this area can also be divided clearly by pollen assemblage. The pollen assemblage indicated early agriculture and human activity may have existed in this area since early Holocene,but this requires further confirmation by other proxies. It can be found that human activity had no complete disappearance even though this area suffered several flood attacks. Beginning in the Middle and Late Holocene（ ca. 6000cal. aB. P. ）, the ancient cultivated land was founded in the profile, and the abrupt drop of arboreal pollen percentage and the significant growth of Selaginella sinensis percentage revealed the intensive human activities