Thermochronometric evidence of far-field stress transfer in continental collisions

In this dissertation, two low-temperature thermochronometers [fission-track analysis on apatite and (U-Th)/He analyses on zircons] are applied on various tectonostratigraphic units from three collisional settings: (i) the Bitlis-Pütürge Massif (SE Turkey), (ii) the Lesser Caucasus (Georgia, Armenia, Azerbaijan), and (iii) the Strandja Massif (SE Bulgaria and NW Turkey). The aim of the study is to better understand the syn- and post-collisional thermochronological evolution of collisional orogens, thus elucidating the dynamics of stress partitioning and transmission during continental collisions. Another focal point of this study is to constrain better the timing of the Arabia-Eurasia collision in the area of its maximum indentation and clarify the overall evolution of the area. From a general viewpoint, our dataset for the Eurasian foreland north of the Arabia-Eurasia collision (the Bitlis-Pütürge Massif and the Lesser Caucasus region) suggest that the tectonic stresses related to the collision during mid-Miocene time were transmitted efficiently over large distances, focusing preferentially at rheological discontinuities located as far as the Lesser Caucasus and the Eastern Pontides. Since the late Middle Miocene a new tectonic regime is active as the westward translation of Anatolia is accommodating most of the Arabia-Eurasia convergence, thus decoupling the foreland from the orogenic wedge and precluding efficient northward stress transfer. In the Strandja Massif the mechanism of stress transmission was very different. The bulk of the massif has escaped significant Alpine-age deformation, which is recorded only in the northern sector. We argue that in the Strandja orogen the stress mostly bypassed the orogenic prism and focused on the Srednogorie rift basin to the north, rheologically weakened by previous Late Cretaceous back-arc extension.