53. ERATOSTHENES SEAMOUNT: THE POSSIBLE SPEARHEAD OF INCIPIENT CONTINENTAL COLLISION IN THE EASTERN MEDITERRANEAN1Ditza Kempler2 |
ABSTRACTWe compare earlier works, based on available geophysical data and plate kinematic considerations, about the origin and evolution of the Eratosthenes structure within the Eastern Mediterranean tectonic framework, with data from Ocean Drilling Program (ODP) Leg 160. The model under discussion is supported by the ODP data regarding the late evolution of the Eratosthenes Seamount; however, deeper drilling is needed for better understanding of the early history of this structure. Analysis of the available seismic reflection, seismic refraction, and magnetic data in view of the regional geologic history suggests that the deep structure of the Eratosthenes Seamount originated in early Mesozoic time. The ODP data confirm that the Eratosthenes structure, which was located a few hundred kilometers away from the Late Cretaceous/early Tertiary active plate boundary, was not affected by the major tectonic events of that period. The data also reflect the existence of the Eratosthenes structural high already in Late Cretaceous and Eocene times. The ODP data corroborate that the Africa-Anatolia plate boundary was reactivated as the Cypriot Arc, between Cyprus and the Eratosthenes structure, in the late Miocene, through subduction of remnant oceanic lithosphere of the Mesozoic Neotethys beneath Cyprus. The absence of Messinian evaporites on the Eratosthenes Seamount and within the surrounding depression was confirmed by Leg 160 data. Similar data led us to infer that this area formed a Messinian island, which subsided in post-Messinian time. The post-Messinian subsidence shaped the seamount and surrounding natural moat, which in turn are superimposed on the Eratosthenes structural high. The Miocene–Pliocene subduction along the Cypriot Arc changed into collision between Cyprus and the Eratosthenes structure after the elimination of oceanic lithosphere from this junction. The Cyprus-Eratosthenes collision triggered the extreme uplift of southern Cyprus at about 1.5-2 Ma. Pulsed uplift of Cyprus, apparently accompanied by pulsed subsidence of the Eratosthenes area, marks incipient continental collision in the Eastern Mediterranean. The Eratosthenes Seamount, therefore, is the possible spearhead of incipient continental collision and is the best candidate for the study of collisional processes in this area. |
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