Physical modelling of climatic control on multistage fan-delta progradation

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The Sitia Basin (Crete, Greece) comprises an Upper Miocene basin fill that is characterized by prograding fan-delta bodies at the margin and hemipelagic muds in the centre. These muds display an alternation of marls and sapropels, which is also reflected in the clay mineralogy by means of gamma-ray spectrometry. Biostratigraphy enables correlation of high-order variations in gamma-ray intensity with the 20 kyr astronomical cycle of precession. Lower order variations correlate with the 100 kyr cycle of eccentricity. The presence of key beds allows correlation of the basin margin and -centre successions. This correlation suggests that progradational delta bodies have a frequency of 100 kyr and correspond with maxima in the eccentricity cycle. Therefore, we propose that fan-delta formation is triggered by increased surface run-off during wetter periods at this frequency. However, the extent to which these climate variations control deposition is only poorly understood. In order to further test our hypothesis and to quantify the effects of various Milankovitch cycles on fan delta behaviour we propose to perform physical, scaled experiments in the “EUROTANK” flume tank facility. The outcome of these experiments will give insight into the sensitivity and timedependency of sink-to-source systems toward different orders of discharge fluctuations.