Cretaceous to Recent Continental Uplift From Paleobiological Data and Landscape Evolution Modelling

Abstract:

The least equivocal constraints on timing and amplitude of vertical continental motions on geological timescales come from the distribution of rock formed in shallow marine environments. However, obtaining enough observations at sufficiently large spatial and temporal scales ($\sim100-10,000$ km, $\sim1-100$ Ma) to constrain histories of regional topographic evolution remains challenging. To address this issue we adapted modern inventories of paleobiological and paleoenvironmental data to generate a new compilation of $>24,000$ spot measurements of uplift on all continents and numerous ocean islands. The compilation provides self-consistent, and in places, high-resolution ($<100$ km, $<1$ Ma), measurements of Cretaceous to Recent (post-deposition) net uplift across significant tracts of most continents. We show how histories of uplift constrained by this inventory can test, and be augmented by, inverse modelling of continental-scale drainage patterns. Uplift histories from western North America and eastern South America are combined with geophysical observations (e.g. free-air gravity, shear and Pn-wave tomography) and simple isostatic calculations to determine origins of topography. Uncertainties associated with paleobathymetry, post-deposition compaction and glacio-eustasy are assessed. Isostatic calculations are used to explore how lithospheric thinning and mantle thermal anomalies may generate uplift of the observed wavelengths and amplitudes. The results emphasize the importance of large inventories of paleobiological and geomorphic data for understanding histories of landscapes, the environment, and tectonic and mantle convective processes.