Physical modelling of climatic control on multistage fan-delta progradation

锡蒂亚盆地（希腊克里特岛）由上中新世盆地填充物组成，其特征是边缘为推进的扇三角洲体，中部为半深海泥质。这些泥浆呈现泥灰岩和泥砾岩的交替，这也通过伽马射线能谱法反映在粘土矿物学中。生物地层学使伽马射线强度的高阶变化与20 kyr天文岁差周期的相关性成为可能。低阶变化与100 kyr的偏心周期有关。关键层的存在使盆地边缘和盆地中心层序的对比成为可能。这种相关性表明，前积三角洲体的频率为100 kyr，与离心旋回的最大值相对应。因此，我们提出扇三角洲的形成是由在这个频率的潮湿时期增加的地表径流引发的。然而，人们对这些气候变化对沉积的控制程度知之甚少。为了进一步检验我们的假设，并量化各种米兰科维奇循环对扇三角洲行为的影响，我们建议在“EUROTANK”水槽设施中进行物理的、规模化的实验。这些实验的结果将深入了解汇源系统对不同量级的放电波动的敏感性和时间依赖性。

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.