Tectonic Re‐Organization and Onset of South Caspian Escape Tectonics at 1.8–2.4 Ma

We use offshore seismic reflection data combined with published geologic and geodetic studies to examine the timings and styles of deformation around the South Caspian Basin, an enigmatic aseismic ‘block’ within the Arabia‐Eurasia collision that moves relative to its surroundings. We show that the presently active tectonics of the South Caspian began relatively recently, likely in the range 1.8–2.4 Myr, with components of both shortening and lateral‐slip along its northern and western edges. Along the northern margin (the Absheron Ridge), structures related to the active tectonics are superposed on an older tectonic configuration related to north–south shortening and subduction of the South Caspian, ending in the Miocene at ~6 Ma. In the west (Kura margin), the present‐day oblique right‐lateral transpression began at 1.8–2.4 Myr, replacing an earlier phase of shortening. The tectonic history is hence one of initial Miocene shortening and northward‐directed subduction of SCB basement, followed by a hiatus in deformation along the Absheron ridge, which we infer to result from a switch to oroclinal bending in the ranges surrounding the basin until 1.8–2.4 Myr. At that time the active tectonic configuration was established, and the basin began to be expulsed to the northwest. This change led to the development of major transpressional fault systems along its north, east, and southern margins, the likely resumption of underthrusting of SCB basement northward beneath the Absheron ridge, and the start of underthrusting and incipient subduction beneath the Kura basin along its western margin. The various short‐lived stages in the destruction of the South Caspian have potential for insight into the late stages of basin closure and the transition to mature continental collision.