PRECESSION-PUNCTUATED GROWTH OF A LATE MIOCENE SUBMARINE-FAN LOBE ON GAVDOS (GREECE)

Sedimentary cycles in an upper Miocene succession of hemipelagic sedim ents (marls) and laminites (sapropels) were deposited in an outer-arc basin and are related to the astronomical cycles of precession and ecc entricity. Individual marl-laminite couplets correspond with the cycle of precession which has a periodicity of about 22 kyr. The lower part of the succession contains a turbidite interval comprising a number o f distinct turbidite sequences. The turbidite sequences occur within o r substitute entirely the laminite beds, so that turbidite deposition is similarly precession punctuated. The turbidite facies is characteri stic for small, prograding fan lobes fed by small-volume turbidites. T he abundant plant remains, the local palaeogeographic setting and the association with laminites (related to wet climate) suggest a river-fe d submarine fan-lobe, where the timing of sediment transport is largel y controlled by river floods during periods of high precipitation and continental run-off. The onset and ending of the turbidite interval is most likely finked with either autocyclic processes or by tectonic st eepening of the hinterland relief. Sea-level changes seem least import ant for the triggering of turbidites, which is in contrast with curren t beliefs.