Gypsum caves as indicators of climate-driven river incision and aggradation in a rapidly uplifting region

Abstract

Detailed geomorphological analysis has revealed that subhorizontal gypsum caves in
\nthe Northern Apennines (Italy) cut across bedding planes. These cave levels formed during
\ncold periods with stable river beds, and are coeval with fluvial terraces of rivers that
\nflow perpendicular to the strike of bedding in gypsum monoclines. When rivers entrench,
\nrenewed cave formation occurs very rapidly, resulting in the formation of a lower level.
\nRiver aggradation causes cave alluviation and upward dissolution (paragenesis) in passages
\nnearest to the river beds. The U-Th dating of calcite speleothems provides a minimum age
\nfor the formation of the cave passage in which they grew, which in turn provides age control
\non cave levels. The ages of all speleothems coincide with warmer and wetter periods when
\nCO2 availability in the soils covering these gypsum areas was greater. This climate-driven
\nspeleogenetic model of epigenic gypsum caves in moderately to rapidly uplifting areas in
\ntemperate regions might be generally applicable to karst systems in different geological and
\nclimatic conditions.