Lithological Controls on Granite Weathering: Insights from Stepwise Water-Rock Interaction Experiments

Weathering is instrumental in sculpting granite landforms and regulating the global carbon cycle. Variations in lithology and water-rock interactions (WRI) drive spatial differences in weathering flux， ultimately controlling large-scale granite morphology. To elucidate these processes， Jiuhua Mountain UNESCO Global Geopark (eastern China)， characterized by a typical peak-hill-basin granite assemblage developed on A-type (syenogranite) and I-type (granodiorite) granites， was selected as the study area. Laboratory simulations representing successive weathering stages were conducted under controlled hydrological， thermal， and chemical conditions. Results show that A-type granite forms more permeable crusts and exhibits higher structural stability， whereas I-type granite undergoes stronger chemical alteration and structural breakdown. Temperature is the primary control on WRI intensity， while pH plays a secondary role. Plagioclase contributes more to weathering than K-feldspar. Internal circulation and environmental factors jointly regulate solute accumulation and overall weathering dynamics. These coupled effects provide a mechanistic explanation for the peak-hill-basin assemblage at Jiuhua Mountain， offering new insights into granite landscape evolution.