Study Of Paleo-monsoon Recorded By Aeolian Deposit In The Coastal Area Of East Fujian Since The Late Pleistocene

The red sand, the quaternary sediments, widely distributes along the southeast coast and south coast of China. Its distribution, sedimentary characteristics, sedimentary dates, rubification, and formation have been studied extensively. In this paper, QingFeng, Pingtan, was chose as the study area, which is characteristic of the red sand and responds actively to monsoon changes. And the purpose of the paper was to explore the correlation of the red sand, sand sediments in the east of Fujian, and the fluctuations of East Asian monsoon. OSL dating, grain size, magnetic susceptibility and spectrum were accomplished, and the conclusions could be drawn as following:First, OSL dating has greatly improved the accuracy of measurement. By means of OSL dating, age-depth relationship was set up and the probability age rang of the profile was confirmed, that was 140 ka.B.P.-58ka.B.P., belonging to the last interglacial periods.Second, all the samples were measured by Mastersizer 2000 Laser Grain-size Instrument. By means of grain-size Parameters, grain-size curves, combined with Sahu's formula, the wind-sedimentary environment of the samples was further demonstrated.Third, all the samples were measured by Bartington MS2 Instrument. The implications of magnetic susceptibility of the samples were analyzed. At the same time, Combined with the fitting pale-temperature of Tian'e Cave, sedimentary periods were divided into several detailed periods. And then, analysis on the fluctuation of magnetic susceptibility and the reasons of its fluctuation were carried out. To the conclusion, magnetic susceptibility could reflect cool-warm climate changes of the study area in the sedimentary periods.Fourth, by means of grain-size standard deviation variation, the sensitive grain-size was extracted. Furthermore, magnetic susceptibility and sensitive grain-size were analyzed by Redfit Noised Analysis Software. To the conclusion, magnetic susceptibility and grain size could correspond well to paleoclimatic variation. meanwhile, the sedimentary periods of Aeolian Deposit were also detected, that were Milankovitch cycles(including a 41ka eccentricity cycle, a 16ka precession,14ka and 12ka semi-precessions)and millennial-scale cycles (including 7ka,6ka and 5ka quasi cycles).Compared with the relative studies' results, the samples were characterized with multi-spectrum of tropical monsoon.Finally, curves of Tian'e Cave stalagmite isotope, Sanbao/Huluδ18O records and atmosphericδ18O record from Vostok ice core were chose to compare with the magnetic susceptibility and sensitive grain-size of samples, which revealed that curves of samples corresponded well to the selected curves. Therefore, Aeolian deposit could respond actively to Asian monsoon changes.