Elemental Composition Features of Loess-Paleosol Profile in Fengning, Hebei Province

Mao Xin; Liu Linjing; Li Chang'an; Zhang Yufen; Zhao Hongmei; Bi Zhiwei; Jiang Gaolei

doi:10.3799/dqkx.2017.538

Abstract：The loess deposited in the upper reaches of the Luanhe River valley is an important geological record of past palaeoclimate and palaeoenvironment in the Bashang Plateau of Hebei Province.Due to the scattered distribution and small thickness of the loess in this region,it has attracted little attention in previous studies.In order to discuss the genesis,provenance and chemical weathering intensity of loess in this region,the elemental composition analysis of 77 samples from typical loesspaleosol profile was carried out and compared with known typical aeolian deposits.The results show that:(1) The sum of major elements (SiO2,Al2 O3 and Fe2 O3) and UCC (Upper Continental Crust)-normalized patterns of Fengning profile are similar to those of typical aeolian deposits,indicating that Fengning loess and paleosol were aeolian;(2) Fengning loess underwent weak chemical weathering and paleosol underwent moderate chemical weathering.Compared with the typical aeolian deposits,the sequence of chemical weathering intensity is as follows:Xuancheng aeolian red earth ＞＞ Xifeng red clay and Zhenjiang Xiashu loess ＞ Fengning paleosol and Luochuan paleosol ＞ Luochuan loess ＞ Fengning leoss;(3) The migration feature of major elements reveal that Fengning loess and paleosol finished the primary process of chemical weathering characterized by leaching of Ca and Na,and almost reached the secondary process characterized by leaching of K;(4) The scatter diagram of K2 O/Al2 O3 and Fe2 O2/Al2 O3 are similar to that of Luochuan loess,Luochuan paleosol,Zhenjiang Xiashu loess and Xifeng red clay,indicating that these aeolian deposits might have the same source.The ratio of TiO2/ Al2 O3 is less than that of other aeolian deposits,indicating that Fengning loess and paleosol have other source.