Supradetachment basin evolution unraveledby detrital apatite fission track analysis - Theexample of the Gediz Graben (MenderesMassif, Western Turkey)

National audienceThe Menderes Massif of Western Turkey in an outstandingexample of Tertiary continental metamorphic core complex exhumedduring upper Oligocene – Miocene times; its exhumationwas accompanied by the development of a series of continentalE-W trending basins. Several studies addressed the exhumationhistory of the massif, but the relative relevance of the identified exhumationevents and the depositional history of these basins is stillpoorly defined. In this study, we focused our investigations on theGediz Graben supradetachment basin, which has been used as acase history to illustrate the benefits of a comprehensive approachto detrital apatite fission track dating that combines analysis ofmodern river sediments, analysis of fossil sedimentary successions,and mineral fertility determinations. This approach allowed us (i)to constrain the maximum age for the beginning of sedimentationin the basin, after providing that post depositional annealing wasnegligible, (ii) to identify major exhumation events recorded in theNeogene-to-Quaternary sedimentary fill of the basin, (iii) to reconstructthe exhumation history of bedrock unit at the footwall andat the hanging wall of the Gediz detachment, and (iv) to reconstructthe modern short-term erosion pattern of the study area.Three main exhumation events with different spatial relevancehave been identified in the area, related to the main exhumationof the Menderes Massif, to a major structural reorganization inthe basin resulting in the exhumation of the margins of the CentralMenderes Massif, and to a localized event related to the finalexhumation of the Gediz detachment and its intrusive footwall.Our results, integrated with field evidences, allowed us to proposea coherent 4D reconstruction for the evolution of the GedizGraben. The implications of the proposed model for the Cenozoicevolution of the Menderes Massif and for the Aegean extensionalregion more in general are eventually discussed