Subsurface critical zone structures (SCZs) refer to the spatial variation in the interactive layers underground. Although SCZs greatly affect terrestrial biogeochemical and hydrological cydes, underpinning mechanisms are poorly documented. Herein, we characterized the SCZs of a typical red soil in subtropical China, a type of soil with vast global distribution. The thickness information of three layers was derived from hand augers, boreholes and ground-penetrating radar (GPR) radargrams and incorporated into geographically weighted regression (GWR) models for the reconstruction of paleotopography (Cretaceous sandstone). The interpreted GPR results in terms of thicknesses and interfaces for the three layers were consistent with the borehole logs. The trained GWR models accounted for 43%-77% of the spatial variations in the three layers. The paleotopographic elevations were highly correlated with those of the current land surface (r = 0.85). Spatial analysis showed that the rougher paleotopography was inherited by the current landform. The SCZs evolution involving mainly the mantling covered by Quaternary red clay (QRC) was primarily driven by terrain attributes. These findings may enhance our understanding of the interaction between the paleocli mate and paleoe nvironment. The combination of geophysical techniques, geochemical indicators and spatial prediction techniques provides an effective tool for understanding QRC land form evolution. (C) 2020 Elsevier B.V. All rights reserved.
Bibliographical noteThis study was supported by the National Natural Science Foundation of China (grant No. 41571130051, No. 41771251 and No. 41977003), the National Key Research and Development Program of China (No. 2018YFE0107000) and the UK Natural Environmental Research Council (NE/N007611/1). We thank the individual authors of each study regarding critical zone research in the Red Soil CZO. We are grateful to Dong-Sheng Yu, Li-Gang Zhou, Shun-Hua Yang and Yue Zhao for their support in conducting the GPR survey. We are grateful to Qin-Bo Cheng for interpreting the radargram images.
Data Availability: All radargram data, soil data and environmental predictors used in this study are available from the corresponding author upon request.
- critical zone
- ground-penetrating radar
- Red Soil Critical Zone Observatory
- landscape evolution
- GROUND-PENETRATING RADAR
- Critical zone
- QUATERNARY RED CLAY
- GEOGRAPHICALLY WEIGHTED REGRESSION
- SOIL-WATER STORAGE
- Landscape evolution
- Ground-penetrating radar