摘要
地层时代和地层划分研究一直是基础性、先导性工作,随着科学研究的深入和材料的丰富,地层划分不断被重新认识。黄土地层时代和划分主要依靠OSL、^(14)C、古地磁和磁化率的对比。中原邙山因发育巨厚的马兰黄土而闻名中外,但地层划分却出现了不同的认识。早期对赵下峪剖面的研究认为L_1层厚98 m,并发育L_1SS_1弱古土壤层;剖面底部出露最老地层为S_(10)层。后来的观点把早期的L_1层划分为L_1、S_1、L_2层,剖面底部出露最老地层为S_(11)层。通过对B/M界线进行详细的古地磁研究,剖面上部补充年代测试样品,结合已有测年结果,分析认为早期对L_1的划分和对剖面最老地层的确认是正确的,但B/M界线位置划分有误;而后期的研究对B/M界线位置的划分是正确的,但把底部最老地层划分为S_(11)是不当的,同时把马兰黄土中弱古土壤层L_1SS_1划分为S_1也是不合适的。地层对比表明,邙山黄土发育了S_0—S_(10)黄土—古土壤序列,B/M界线位于L_8下部。
Stratigraphic age and stratigraphic division are basic and pilot work.As the research moves along,stratigraphic division will be re-recognized.The age and division of the loess stratigraphy mainly depend on OSL,14 C,paleomagnetism and magnetic susceptibility.Mangshan is famous for the extremely thick Manlan loess,while there exists different understandings about the stratigraphic division.Early research about Zhaoxiayu section revealed that the thickness of L 1 is 98m,with the weakly developed palaeosol L 1 SS 1,and the oldest stratum exposed at the bottom of the section is the palaeosol S 10.Later,the early L1 layer was divided into L1,S1 and L2 layers,and the oldest layer at the bottom of the section is the palaeosol S11 layer.Based on detailed paleomagnetic study of B/M boundary,combined with previous dating results,it is believed that the early division of L1 and the confirmation of the oldest stratum are correct,but the position of B/M boundary is mislocated.The late-stage studies are right in the position of B/M boundary but wrong in the confirmation of the oldest stratum,and also it’s not appropriate to divide the palaeosol layer L 1 SS 1 of the Malan Loess into S 1.The stratigraphic correlation shows that the Mangshan loess include S 0-S 10 loess-palaeosol sequence,and the B/M boundary is located at the bottom of the loess L 8.
作者
杨州
王书兵
蒋复初
王喜生
傅建利
YANG Zhou;WANG Shubing;JIANG Fuchu;WANG Xisheng;FU Jianli(Henan Xinyang Hydrology and Water Resources Survey Bureau,Xinyang 464000,Henan,China;Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China)
出处
《地质力学学报》
CSCD
2018年第2期274-282,共9页
Journal of Geomechanics
基金
国家自然科学基金项目(40302025
40972223
41272393
41472327)
中国地质科学院重点开放实验室专项资金资助项目(KL05-13)
中国地质大调查工作项目(1212010711705)
关键词
马兰黄土
B/M界线
地层划分
邙山
Malan loess
B/M boundary
stratigraphic division
Mangshan