| Abstrakt: |
By analyzing the geochemical characteristics of the loess-covered red weathering crust in the Qidingshan area of southern Liaoning, the development characteristics are studied and compared with those of red weathering crust in Hunan, Guangxi, Guizhou, Yunnan, Tibet, Shanxi, and Gansu in order to understand the development characteristics of loess-covered red weathering crust and provide a preliminary basis of the spatial difference of its development characteristics in different regions. The chemical element experiments show that the average distribution of the main elements for the red weathering crust in the Qidingshan section experiences the following trend: SiO2 > Al2O3>Fe2O3>K2O>CaO>MgO>Na2O. CIA is between 83.19-86.89, Ba is between 0.26-0.35, A/NK is between 6.10 and 7.47, A/CNK is between 3.93 and 4.99, S/A is between 5.24 and 6.47, and S/R is between 4.53 and 5.50. The conclusion shows that the red weathering crust from the Qidingshan section has a positive weathering sequence, which is the product of weathering the underlying bedrock. The chemical composition is mainly composed of SiO2, Al2O3, and Fe2O3. The sum of the three is more than 86%, which constitutes a reductive environment, indicating desiliconization and deironing. This stage develops in a subtropical climate with a high level of chemical weathering. The climatic conditions of the red weathering crust development are provided in Liaoning Province from 116.13 Ma to 90.48 Ma and from 17.70 Ma. to 9.44 Ma, combined with the residual red weathering crust and stone bud, and can be considered to be from the mid-Miocene or earlier. The red weathering crust of southern Liaoning was a two-stage development process before the Quaternary, namely, the flattening-shelling, cutting-reddening period. The Quaternary has only had a cutting - reddening period. The element characteristics of the red weathering crust of Hunan, Guangxi, Guizhou, Yunnan, Tibet, Shanxi, Gansu, and Liaoning are highly consistent. The weathering intensity and direction in each region are similar. Except for the weak desiliconization, deironing, and aluminum-rich trend in southern Liaoning, other regions indicate a trend of desiliconization and aluminum-rich ironification, which suggests that the loess-covered red weathering crust is in a reductive environment. The latitude and longitude factors have similar effects on the desiliconization and aluminum-rich ironation process of red weathering crust. Compared with the longitude factors, the latitude factors have a greater influence on the alkali metal and alkali metal leaching of red weathering crust. In general, under the premise of less influence from the parent rock, the climatic factors under latitude control are the main factors determining the development of red weathering crust. [ABSTRACT FROM AUTHOR] |
