CLIMATE AND RHEOLOGICAL CONTROL IN CONVERGENT MARGINS FROM A GEOCHRONOLOGICAL PERSPECTIVE

Cooperation among surface, rheological, and tectonic processes associated with convergent margins influences particle trajectories in a manner that characteristically leads to flow bifurcation and massive strength heterogeneities. In the early stages of convergence, influence on trajectories is dominantly exerted by atmospheric advective perturbations via the concentration of surface processes. With time, on a scale controlled by thermal Peclet number, rheological effects dominate particle trajectories, leading to the non-linear positive feedbacks that characterize tectonic aneurysm behavior.

This transition from flow paths dominated by surface processes to rheologically dominated trajectories can be identified in modern and ancient orogens from the geochronological patterns generated from a broad spectrum of thermochronological methods. Through examination and comparison of the geochronological patterns of three modern plate corners where non-linear aneurysm behavior can be demonstrated, Nanga Parbat (western Pakistan), Namche Barwa (eastern Tibet), and St Elias (southern Alaska) we have identified the transition from climate to rheological control that persists in the geological record of ancient orogens.