Magnetostratigraphy and Astronomically Tuned Time Scale of Yangtze Delta since Pliocene
Xie Jianlei
Zhang Kexin
Ma Xiaolin
Zhao Baocheng
Zhang Ping
Abstract：There is also uncertainty about the magnetostratigraphy in the Yangtze delta.In order to establish a reliable time scale,and provide constraints for sedimentary environment and climate evolution,based on chronostratigraphy and magnetostratigraphy,in this paper astronomical time scale of the LZK1 borehole in the Yangtze delta is researched,and established the chronological framework is established.The results show that M/B,Ga/M and Gi/Ga boundaries locate at 143.0 m,219.0 m and 296.6 m separately.The deposit cycles are clear and the sedimentary rate has obvious phases,which was influenced by the climate and sedimentary environment.The tuned frequency dependent susceptibility record reveals orbital periods including 125 ka,96 ka,41 ka,23 ka,22 ka,18 ka,and is correlated with ETP curves enormously in orbital periods,the confidence interval exceeds 95％.The band-pass filtering curves of 100 ka,41 ka,23 ka circles coincide with the corresponding orbital parameter curve in phase and amplitude in total,while existing some inconformities at certain times.The inconformities may be caused by low sedimentary rate or abrupt change of sedimentary rate.In this paper,a conclusion is drawn that in the ongoing subsidence areas with temporary depositional hiatus,as long as the sampling resolution can be assured,we can establish reliahle chronological framework by orbital tuning.
Keywords：Yangtze deltamagnetostratigraphyorbital tuningastronomical time scaleclimate periodsedimentologyQuaternary
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：14( 1760-1773 )