Original paper

Weathering and landform development in a subtropical mountainous terrain, Veladero massif, Mexico

Migon, Piotr; Alcántara-Ayala, Irasema

Abstract

Granite topography of the Veladero massif, south Mexico, is a heavily dissected all-slopes type of relief. Rock slopes and tor-like residuals occur near the crests, whereas exposures within middle and lower slopes show deeply disintegrated granite, often with corestones. Weathering grade is low to intermediate, with kaolinite, smectite and illite present in the most weathered top parts of the saprolite and in the colluvium. Hillslope geomorphology indicates that shallow debris slides are a common means of mass transfer, leading to the build-up of colluvial aprons. Valley floors are filled by thick debris flow deposits, further pointing to the role of episodic, large-scale geomorphic events. A long-term balance between the rate of weathering front descent and the rate of slope lowering is suggested. Current landforms and geomorphic legacy in the Veladero massif appear consistent with the steady-state evolutionary model, inferred from rock exhumation studies.