<p>The Lesser Caucasus (LC) double-wedge orogen accommodates the crustal shortening due to far-field effects of the collision between the Arabian and Eurasian plates. Subsequent convergence of Arabia and Eurasian plates during the late Alpine time caused extensive intracontinental deformation in the LC. Herein we introduce the active deformation structural style of the Georgian part of the LC orogen based on seismic reflection profile, several oil-well, and surface geology data. Seismic reflection data reveals the presence of a Khrami basement thrust sheet, fault-related folds,<em> </em><em>triangle zone,</em><em> </em><em>and duplexes. </em>The rocks involved in the deformation range from Paleozoic basement rocks to Pliocene-Quaternary basaltic lava flows.</p> <p>Pliocene-Quaternary lava flows are involved in compressional deformation and are related to an out-of-thrust sequence of the Khrami basement thrust sheet. Based on the interpreted seismic reflection profile, the crustal-scale duplex was recognized under the basement thrust sheet which propagates northward along the Early Jurassic shale layers.</p> <p>The structural architecture and tectonic evolution will be briefly presented and discussed in the new regional balanced and reconstructed cross-section across the axial zone and retro-wedge of the LC and published fission-track data (Gusmeo et al., 2021, 2022), as well as detailed examples of active tectonics, and seismicity (e.g., Tsereteli et al., 2016).</p> <p><strong>Reference</strong></p> <p>Gusmeo, T., et al. (2022). Tectono-thermal evolution of central Transcaucasia: Thermal modelling, seismic interpretation, and low-temperature thermochronology of the eastern Adjara-Trialeti and western Kura sedimentary basins (Georgia). J. As. Earth Sci. 238, 105355.</p> <p>Gusmeo, T., et al. (2021). Structural inversion of back-arc basins-The Neogene Adjara-Trialeti fold-and-thrust belt (SW Georgia) as a far-field effect of the Arabia-Eurasia collision. Tectonophysics 803, 228702.</p> <p>Tsereteli, N. et al. (2016). Active tectonics of central-western Caucasus, Georgia. Tectonophysics 691, 328-344.</p> <p><em><strong> </strong></em></p> <p> </p> <p> </p>

<p>The integration of low-temperature thermochronological and thermal maturity analyses constrains the maximum temperatures experienced during burial by the sedimentary fill of the central sector of the Greater Caucasus basin and the timing of its structural inversion. Raman spectroscopy, illite percentage and stacking order in illite-smectite mixed layers, illite crystallinity index, and Rock-Eval Pyrolysis analyses indicate that the maximum paleotemperatures experienced by the Greater Caucasus basin fill increase progressively from about 100 °C in the southern foothills of the central Greater Caucasus to close to 400 °C approaching the axial zone of the orogen. Apatite fission-track and apatite and zircon (U-Th)/He analyses along the same transect yielded ZHe ages between about 137 and 5 Ma, AFT central ages between about 37 and 4 Ma, and AHe ages between about 10 and 2 Ma, with progressively younger ages approaching the axial zone of the Greater Caucasus. Statistical inverse modelling of thermochronological data, integrating thermal maturity results and all other geological and geochronological constraints available, points to episodic exhumation during structural inversion of the central Greater Caucasus basin. Such basin was first partially inverted in Late Cretaceous/Paleocene times following Northern Neotethys closure along the Sevan-Akera suture zone; renewed basin inversion occurred since Middle-Late Miocene times as a consequence of far-field compressional stress transmission from the Arabia-Eurasia hard collision along the Bitlis-Zagros suture zone. It should be emphasised that this sequence of events applies only to the central portion of the Greater Caucasus and by no means should be extended to the other parts of such a large and complex orogenic system.</p>