Uplift of Trail Ridge, Florida, by Karst Dissolution, Glacial Isostatic Adjustment, and Dynamic Topography

Abstract

AbstractThe present elevation of Trail Ridge, a purported Pleistocene paleoshoreline (2.21 ± 0.38 Ma) up to ~70 m high, is attributed to isostatic uplift from karst‐induced mass loss of the underlying Florida Platform. However, glacial isostatic adjustment, dynamic topography (DT), and elastic flexure also contribute to the observed topography. We investigated the combined contribution of these geophysical processes to the elevation of Trail Ridge by adapting a numerical model of karst‐induced Airy isostatic uplift that is driven by sea level change since ~3 Ma with a gravitationally self‐consistent glacial isostatic adjustment model. We treat DT as a free parameter and explore a spectrum of scenarios, from dynamic subsidence (−25 m/Myr) to dynamic uplift (+25 m/Myr), with values consistent with mantle convection simulations for the region. We demonstrate a trade‐off between the age of Trail Ridge, karstification efficiency, and DT rate that necessitates robust estimates of two of these variables when solving for the third. For example, adopting spring‐efflux‐derived estimates of subsurface carbonate dissolution (1 m/38,000 yr) and a 10 m/Myr dynamic topographic uplift for the northern Florida Platform predicts an age of ~2.1 Ma for a model 70 m elevation marker, consistent with the bounds of the electron spin resonance optical dating geochronology. In contrast, by assuming a more rapid carbonate dissolution efficiency (1 m/11,000 yr) and dynamic subsidence of −15 m/Myr predicts a similar age. A refined karst‐induced isostatic uplift model age for Trail Ridge requires both improved rates of regional karst dissolution, dynamic topographic change, and elastic flexure.