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新疆黄土岩石磁学特征与地层性质的对应关系具有鲜明的区域特征。本文选取沙湾黄土剖面进行较为系统的岩石磁学分析。研究结果表明,沙湾剖面的磁性矿物组成与黄土高原及新疆北部其他黄土剖面相似,以亚铁磁性矿物(如磁铁矿、磁赤铁矿)为主要的载磁矿物,同时含有一定量的不完全反铁磁性矿物(如赤铁矿、针铁矿)和顺磁性矿物。假单畴(PSD)和多畴(MD)为样品的主要磁畴特征,部分土壤样品中磁性矿物磁畴状态表现为单畴(SD)。进一步分析发现,磁化率与地层对应关系较为复杂,剖面3m以上地层中的磁化率及其他相关磁学参数与成壤强度呈现正相关关系,全新世以来发育的古土壤中磁化率值较高,细颗粒磁性矿物含量也较高;而3m之下地层中磁学参数显著表现为风力强度驱动变化模式。古风场强度的变化可能对剖面整体磁学性质具有一定的影响,成壤作用受到风动力条件的制约,主要决定了较细颗粒磁性矿物的含量变化。χ_(ARM)/SIRM参数与磁化率相比对地层成壤强度的指示作用更为明显。
The corresponding relationship between the magnetic properties of the loess rocks in Xinjiang and the stratigraphic features has distinctive regional characteristics. In this paper, we select the Shawan loess profile for systematic rock magnetism analysis. The results show that the magnetic mineral composition of Shawan section is similar to that of other loess sections in the Loess Plateau and northern Xinjiang. Magnetic minerals such as magnetite and maghemite are the main magnetic minerals and contain a certain amount of Incomplete antiferromagnetic minerals (such as hematite, goethite) and paramagnetic minerals. Pseudo-mononuclear (PSD) and multi-domain (MD) are the main domain features of the samples, and the domain states of magnetic minerals in some soil samples are single domain (SD). Further analysis shows that the correlation between magnetic susceptibility and formation is more complicated. The magnetic susceptibility and other relevant magnetic parameters in strata above 3m have a positive correlation with the soil strength. The values of susceptibility in ancient soil developed since the Holocene are higher, The fine-grained magnetic minerals are also high, while the magnetic parameters in the formations below 3 m are marked by the wind-driven changes. The change of the ancient wind field intensity may have certain influence on the overall magnetic properties of the profile, and the pedogenic effect is restricted by the wind and dynamic conditions, which mainly determines the content changes of the finer granular magnetic minerals. The effect of χ_ (ARM) / SIRM parameters on susceptibility to stratum formation is more pronounced than that of susceptibility.