Print this pageLower and Middle Miocene Carbonate Platforms in the Central Mediterranean: Sequence Stratigraphy and Paleoceanography
MUTTI, MARIA, DANIEL BERNOULLI, SILVIA SPEZZAFERRI, and PETER STILLE
A fundamental control on sequence stratigraphic packaging is the relationship between accommodation and rates of sediment supply. Rates of shallow water carbonate production are de-pendant on a number of factors and change through time. Environment-related factors such as changes in oceanic circulation patterns and temperature of shallow water masses leave their record in shallow and deep water carbonates and need to be better understood.
We evaluate the impact that paleoceanographic factors have on rates of shallow water carbonate sediment production using two case studies of Early-Middle Miocene age, the Malella in the Southern Apennines and the Hyblean region in Sicily. We use a sequence stratigraphic approach, integrated with detailed biostratigraphy and r-isotope stratigraphy. Both settings are characterized at the second order scale (late Aquitanian to late Serravallian) by ramps with a lower onlapping wedge of plankton-rich marls, and up-dip transgressive open-marine carbonate, and a late highstand succession of rhodalgal and coral buildups. Sr-isotopes were used to date hardgrounds developed regionally at the base of the on lapping wedges, giving an age of 20-21 Ma. This age corresponds to the closure of the marine connection with the Indo-Pacific area and the consequent drastic changes in circulation in the Mediterranean. Stable isotope time-series on benthic and planktic foraminifera indicate relatively cool water temperatures at the base of the onlapping wedges warming up relatively quickly immediately before the deposition of the late highstand successions.
Our data indicate how variations in water temperatures, coupled with drastic changes in water circulation, severely affected rates of carbonate production during the deposition of a second order sequence and had the effect of accentuating the transgressive trend within the sequences.