Role of the Eratosthenes Seamount in Collisional Processes in the Eastern Mediterranean

Abstract

The Eratosthenes Seamount plays a critical role in the tectonic evolution of the Eastern Mediterranean, including the uplift of the Troodos ophiolite of Cyprus. It also represents an important early collisional stage in the general process of plate suturing and mountain building. Drilling during Ocean Drilling Program Leg 160 has elucidated the history of the Eratosthenes Seamount from the late Mesozoic to the present day and has provided data to test several recent hypotheses concerning the tectonic evolution of the Eastern Mediterranean region. Specifically, it is inferred that the uplift of Cyprus at about 1.5 Ma was activated by collision of the seamount with the upper plate of a subduction zone on which Cyprus is located. During the late Mesozoic, the Eratosthenes Seamount underwent mainly deep-water pelagic deposition in a stable tectonic setting adjacent to the passive continental margin of North Africa. By the Miocene, the seamount was tectonically uplifted, perhaps in response to subduction or initial collision, and then underwent shallow-water carbonate deposition. At about the late Miocene to early Pliocene, the seamount underwent inferred extensional faulting and breakup, followed by rapid subsidence to water depths of up to 2000 m. The data support the hypothesis that the Eratosthenes Seamount foundered as a consequence of collision with a convergent margin to the north. Regional uplift of Cyprus was, however, delayed until approximately 3 m.y. later, possibly reflecting the time necessary for sufficient crustal thickening to take place at depth to trigger uplift. The tectonic processes outlined above are also applicable to the early stages of collision of a number of orogenic belts, including the Mediterranean Tethys and the Appalachians.