We investigated rock outcrops spanning the middle Miocene, global
climate-cooling step on the Maltese Islands in order to reconstruct
continental weathering rates and terrigenous fluxes, as well as to
explore the coupling between these later, regional climate and carbonate
accumulations. Sedimentation at this location was dominated during the
Oligocene and early Miocene by a transitional platform to slope
carbonates but progressively switched to a clay-rich carbonate slope
system in the middle Miocene. Around 13 Ma, an abrupt change toward
clay-dominated marls occurred, and marl deposition persisted until the
Tortonian (ca. 12 Ma), when a shallow-water carbonate ramp was
reestablished. Clay mineralogy and bulk-rock oxygen isotope analyses
suggest that the deposition of the Blue Clay formation was mainly caused
by global climate change and related change in the rate of continental
weathering.
A significant negative correlation (112 0.65) exists between the
carbonate content and the 8110 record. This, combined with the variation
of mass accumulation rate of terrigenous material, suggests that
shorter-term periods of globally cooler climate (Mi events) were
associated with higher rates of accumulation in continental-derived
material. Since during the Miocene Malta was attached to the North
African Margin, we propose that the observed trends were due to a
regional increase in rainfall during cooler periods, which consequently
increased continental weathering and runoff. We further suggest that
this pattern was linked to the perturbation of atmospheric fronts due to
an increased thermal gradient during the Miocene. Thus, regional
increase in rainfall might have been linked to the northward migration
of the Intertropical Convergence Zone (ITCZ).