Discrete Plio-Pleistocene phases of tilting and counterclockwise rotation in the southeastern Aegean arc (Rhodos, Greece): early Pliocene formation of the south Aegean left-lateral strike-slip system
Résumé
The island of Rhodos represents an uplifted block in the largely submerged southeastern Aegean forearc. It has a complex history of subsidence, uplift and counterclockwise rotation during the Plio- Pleistocene, in response to the interplay between large-scale geodynamic processes. In this paper, we present a new chronostratigraphic framework for the continental Pliocene Apolakkia basin of southwestern Rhodos. We combine these time constraints with recently published chronostratigraphic data from the marine Plio- Pleistocene basins of northeastern Rhodos to reconstruct rotational and vertical motions. Our palaeomagnetic results identify two rotation phases for Rhodos: c. 10°(9 ±6°) counterclockwise (ccw) rotation between 3.8 and 3.6 Ma, and c. 17± 6° ccw rotation since 0.8 Ma. Between these phases, Rhodos tilted to the SE, drowning the southeastern coast to a depth of 500–600 m between 2.5 and 1.8 Ma, then to the NW, which resulted in the re-emergence of the drowned relief between 1.5 and 1.1 Ma. We relate the rotations of Rhodos to incipient formation of the south Aegean sinistral strike-slip system and the foundering of the Rhodos basin. The previously shown absence of Messinian evaporites in the deep-marine Rhodos basin in combination with the 3.8 Ma onset of ccw rotation of Rhodos constrains the onset of the formation of the south Aegean strikeslip system between 5.3 and 3.8 Ma. The formation of this strike-slip system is probably related to the interplay of oblique collision between the southeastern Aegean region and the northward moving African plate, the westward motion of Anatolia, gravitational spreading of the overthickened Aegean lithosphere and the recently postulated southwestward retreat of the African subducted slab along a subduction-transform edge-propagator fault.