Research On Sedimentary Environment And Paleoclimate Changes Since130Thousand Years Stage In Linfen Basin

Linfen Basin is located in the southeast edge of Ordos Massif;this region is one of the areas where neotectonic movement of ourcountry is very strong. The sequence of loess section in the Binheeast road of the Linfen Basin is intact and clear, which is of greatimportance to reveal the climate change since the last interglacial.It reveals the environment and climate change of the Linfen Basinsince the last interglacial through the analysis of samples, this is acertain foundation for the future climate predictions.Over the last interglacial/glacial climate cycle, Linfen Basinenvironment have taken place corresponding periodic changes, theloess/paleosol is widely dispersed, it provides good evidence forstudying the ancient environment change. Based on the samplingsystem of the loess/paleosol in Linfen Basin in grain-size andmagnetic susceptibility, we picked out the paleoclimate proxiesthose be able to reflect the change, and then analyzed the response.It set up characters and process of the paleoclimatic evolvement inLinfen Basin since130thousand years stage, and more provided apowerful evidence for further discussion of the evolution of climateand environment in the middle reaches of the Yellow River in China. Binhe east road section height850cm, based onsedimentological analysis of section in geain-size and magneticsusceptibility, we picked out the paleoclimate proxies, weconfirmed median grain-size,<16μm content of clay and magneticsusceptibility as the alternative indicators of summer monsoon, weconfirmed>16μm content of clay and magnetic susceptibility as thealternative indicators of winter monsoon.Combining with the sedimentary grain-size, each alternativeclimate index and compared with s analysis of Binhe east roadsection, established sedimentary ssequence stratum since the lastinterglacial period of years of Binhe east section at the top of the850cm of Linfen Basin: depth of the last interglacial850-700cm,corresponding years130-75kaB.P., depth of the last glaciation700-230cm,corresponding years75-11kaB.P., holocene depth230-0cm, corresponding years11kaB.P..According to contrast analysis of the sedimentary section ofyears series and climatic proxy data, the sedimentary environmentof Binhe east section is divided into five stages:S1(MIS5),L1L3(MIS4),L1S2-L1L2-L1S1(MIS3),L1L1(MIS2)andS0(MIS1). The climate at the top of the850cm of Binhe east sectionof Linfen Basin has experienced the following stages:850-700cm(130-75kaB.P.), relatively worm and humid;700-580cm(75-57kaB.P.), relatively arid and cold;580-525cm(57-47kaB.P.), relatively worm and humid, it is the firstworm and humid period of MIS3;525-430cm(47-26kaB.P.), relativelyarid and cold;430-380cm(26-20kaB.P.), relatively worm and humid,it is the second worm and humid period of MIS3; 380-230cm(20-11kaB.P.), relatively arid and cold;230-0cm(11-0kaB.P.),relatively worm and humid, at the same time itis also check out six Heinrich events(H1-H6) and the Younger Dryasduring the last deglacial.From the study found that the sediment records andpaleoclimate changes since the last interglacial at the top of the850cm of Binhe east section of Linfen Basin riparian not only hascharacteristics consistent with a large area, but also has its ownlocal characteristics.