Abstract：Geological hazard prevention and control is a crucial national policy in China. Understanding the intrinsic driving factors of geological hazards is fundamental for disaster mitigation. As a province prone to geological hazards, previous studies in Guangdong have primarily focused on the physical and mechanical properties of rock and soil masses. At the same time, insufficient attention has been paid to the underlying causes of mechanical property deterioration—chemical weathering. This study conducted statistical analyses on 6 841 slope hazard sites (collapses and landslides) in typical igneous and sedimentary rock regions of northern and eastern Guangdong. From the perspective of “chemical water-rock interaction (CWRI)”, major chemical elements (including SiO2, Al2O3, Fe2O3, CaO, MgO, K2O, Na2O, and loss on ignition (LOI)) in 40 samples (weathered rocks, residual soils, and slope-residual soils) from 11 hazard sites were analyzed using X-ray fluorescence spectrometry (XRF). Classic chemical weathering indices—silica-alumina ratio (Si/Al), silica-sesquioxide ratio (Si/R2O3), chemical index of alteration (CIA), and a newly proposed CIA-rate by the author—were calculated to explore the driving mechanisms of chemical weathering intensity on slope hazards. Here, the CIA-rate is equal to the CIA value of the weathered product minus the CIA value of the fresh parent rock, then divided by the CIA value of the fresh parent rock. XRF results revealed that the average CIA-rate of igneous rock weathering products (71.28) was significantly higher than that of sedimentary rock products (21.26), consistent with the 1.4 times higher hazard density in igneous rock areas. In igneous rock regions, slope hazards predominantly occur in fully weathered layers and residual soils with CIA values of 75~85 and CIA-rates of 50~70, particularly at sites with spheroidal weathering bodies or heterogeneous interlayers. In sedimentary rock regions, hazards are often observed in lower fully weathered layers and residual soils with CIA values of 75~85 and CIA-rates of 15~25, where bedding structures and “soft-hard interlayers” facilitate multi-stage or deep-seated landslides. This study demonstrates that the hot-humid climate and intense rainfall in South China enhance surface water and groundwater erosion and corrosion, accelerating chemical weathering. During desilication and enrichment of aluminum/iron, elements such as K, Na, Ca, and Mg are leached. In contrast, clay newbornminerals and iron hydroxides accumulate, weakening the mechanical properties and structural integrity of rock and soil masses. These processes serve as intrinsic drivers of geological hazards. The findings provide a scientific basis for early identification and warning of geological hazards.
Key words：X-ray fluorescence spectrometer; Chemical weathering; Slope geological hazard; Internal factor; Guangdong Province
卿展晖. 基于X射线荧光光谱分析斜坡地质灾害发生的化学风化内在因素[J]. 光谱学与光谱分析, 2025, 45(12): 3472-3479.
QING Zhan-hui. The Driving Force of Chemical Weathering Intensity on Slope Geological Hazards Identified by Using XRF. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2025, 45(12): 3472-3479.
