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Abstract:
We investigate the processes driving spatial-temporal patterns of Cenozoic exhumation in the Mediterranean and the Middle East by compiling >7300 published low-temperature thermochronometric ages and converting them into exhumation rates through a formal inversion process based on thermal modeling and closure temperature kinetics. Exhumation rates are resolved using piecewise-continuous spatial variability and timesteps of five million years. The spatial variability of the inferred rates is constrained by a plate tectonic reconstruction based on the integration of available kinematic data. In this model we recognize different tectonic blocks with a relative homogenous tectono-sedimentary and tectono-magmatic history. The inverted erosion rates for each block are then compared with regional and local geodynamic rates, eustatic curves, and climatic forcing to decipher common patterns and possible teleconnections among different blocks. The results document asynchronous exhumation across different tectonic blocks indicating local (i.e., at the scale of a single orogen) rather than regional (i.e., at the scale of multiple orogens) control on erosion rates. The main processes driving exhumation include collisions of Arabia, Adria, and Iberia with Eurasia, and subduction and retreat of the various Neo-Tethys slabs and back-arc basins. Specifically, we recognize two tectonic domains: collisional deformation zones where exhumation is controlled by surface uplift and erosion, and back-arcs areas where exhumation is controlled by tectonic denudation. In both cases we observe an increase in mean rates and rate variance during tectonic activity, followed by a decrease in each metric as tectonic activity wanes. Finally, we note (with a few exceptions) an overall increase in exhumation rates over most of the Mediterranean and Middle East in the last 5 Ma. This increase is more evident in areas of active tectonics and/or high topographic relief. Although we cannot exclude a tectonic contribution to some of these higher rates, the occurrence of higher exhumation rates, even in regions that did not experience enhanced tectonic activity, indicates that such an increase occurred most likely in response to the late Cenozoic global cooling and the Pleistocene increase in climate cyclicity.
