Controls on plio-quaternary foreland sedimentation in the region of the Maltese Islands

Abstract

Plio-Quaternary sediments on the southern foreland of the orogen produced by African-Eurasian plate convergence vary in thick-ness from > 1km in foreland basin and rift graben depocentres to metre-thick deposits over platform environment where depositional hiatuses merge along widespread subaerial surfaces around the Maltese Islands. The syntectonic sedimentation is the result of three episodes: (i) The development of the Pantelleria Rift south of the Maltese Islands by passive rifting, which became the main depocentre for Lower Pliocene sedimentation until rift shoulder upwarping re-directed subaerial drainage to the NE and towards (ii) the evolving Pliocene Gela foredeep in the NW. (iii) Tectonic uplift and erosion diminished over the Malta region during the Quaternary, gradually increasing the preservation of sediments. Pleistocene sedimentation was controlled by palaeoclimatic fluctuations and accompanying glacio-eustatic sea level changes, ending in seasonal arid climatic conditions. The flooding of the Maltese shelf during the Holocene deposited transgressive sand and gravel directly over Tertiary carbonates. Post-transgressive carbon-ate sedimentation is controlled by the distal location of the shelf within non-tropical and oligotrophic nutrient conditions that allow moderate to low carbonate production along most of the shelf area down to > 50m water depth. The geographical variations in the content of metastable carbonates within biogenic sand are related to shelf long profile and coastal lithology.