Stratigraphy and geochronology of the Eocene volcanosedimentary units in the Hekimhan-Darende (Malatya) region: implications for the development of the Gürün Curl

We present new radiometric (Ar-Ar) age data from the volcanic rocks occurring in the Eocene strata in the Hekimhan and Gürün-Darende (Malaya) regions. The Eocene units in these regions are represented separately by the Tohma and Darende formations, respectively. The two basaltic volcanic interlayers in the Tohma Formation, occurring in the lower and upper parts of the succession yielded Ar-Ar isochron ages of 51.75±0.76 and 42.66±0.43 Ma, respectively, indicating a deposition age of Ypresian-Lutetian interval for the unit. The andesitic volcanic rocks in the basal parts of the Darende Formation yielded an Ar-Ar isochron age of 37.35±0.72 Ma, revealing that the unit was deposited, at least, in the Bartonian-Priabonian interval, much younger than the nummilites-bearing sedimentary units those seen in the Hekimhan area. Based on these data we present a revised stratigraphy of these units. Based on this age data from these units it can be suggested that two distinct sectors of the Anatolide-Tauride Block, the Akdere and Munzur sectors, which were separated originally by a transform fault were tectonically juxtaposed and eroded in the Paleocene times which represents the initial stage of the Gürün Curl, the most prominent structural feature of eastern Taurides in the region.