Chiara Fioroni

Middle Eocene to Late Oligocene Antarctic glaciation/deglaciation and Southern Ocean productivity

During the Eocene-Oligocene transition, Earth cooled significantly from a greenhouse to an icehouse climate. Nannofossil assemblages from Southern Ocean sites enable evaluation of paleoceanographic changes and, hence, of the oceanic response to Antarctic ice sheet evolution during the Eocene and Oligocene. A combination of environmental factors such as sea surface temperature and nutrient availability is recorded by the nannofossil assemblages of and can be interpreted as responses to the following changes. A cooling trend, started in the Middle Eocene, was interrupted by warming during the Middle Eocene Climatic optimum and by short cooling episodes. The cooling episode at 39.6 Ma preceded a shift toward an interval that was dominated by oligotrophic nannofossil assemblages from ~39.1 to ~36.2 Ma. We suggest that oligotrophic conditions were associated with increased water mass stratification, low nutrient contents, and high efficiency of the oceanic biological pump that, in turn, promoted sequestration of carbon from surface waters, which favored cooling. After 36.2 Ma, we document a large synchronous surface water productivity turnover with a dominant eutrophic nannofossil assemblage that was accompanied by a pronounced increase in magnetotactic bacterial abundance. This turnover reflects a response of coccolithophorids to changed nutrient inputs that was likely related to partial deglaciation of a transient Antarctic ice sheet and/or to iron delivery to the sea surface. Eutrophic conditions were maintained throughout the Oligocene, which was characterized by a nannofossil assemblage shift toward cool conditions at the Eocene-Oligocene transition. Finally, a warm nannofossil assemblage in the Late Oligocene indicates a warming phase.

Depositional history of the Epiligurian wedge-top basin in the Val Marecchia area (northern Apennines, Italy): a revision of the Burdigalian-Tortonian succession

The Burdigalian-Tortonian Epiligurian succession in the Val Marecchia area comprehends different lithostratigraphic units deposited in a wedge-top basin during the northeastern migration of the thrust belt. The succession includes shallow-water carbonates passing to mixed carbonate-siliciclastic and to fine-grained politic sediments, capped by fluvio-deltaic coarse-grained deposits. Detailed field work and stratigraphy has allowed to characterize depositional units and unconformities and to delineate the sedimentary and tectonic evolution of the basin. Tectonics exerted a primary control at different stages. During the Burdigalian, a general uplift of the area allowed the onset of shelfal carbonate sedimentation on underlying Ligurian and Epiligurian deep-water sediments. At the Serravallian the sedimentation was influenced by the thrust reactivations which caused a marked asymmetry in the basin geometry and fill. The subsidence increase in the rear part of the basin determined the deposition of a thick succession of relatively deep fine-grained sediments (up to 800 m water-depth) (Serravallian, MNN6a through MNN6b subzones based on nannofossil biostratigraphy) and fossiliferous clays (lower Tortonian, biozones MNN8b-MNN9). Conversely, uplift is activated in the frontal part of the basin, causing the partial erosion of the Burdigalian-Langhian shallow-water carbonates. A relevant amount of this carbonate detritus is delivered to the foredeep, supplying the Marnoso-arenacea Fm. A general uplift of the area in the late Tortonian leads to the deposition of fluvio-deltaic conglomerates supplied by emerged rear sectors of the basin.

Large Reactivated Earth Flows in the Northern Apennines (Italy): An Overview

This paper proposes an overview on ancient earth flows and their reactivation mechanisms. All considerations made herein are the result of direct experience and observation of actual events which have occurred in the Northern Apennines from 1994 to 2006, when many large earth flows reactivated, 17 of which have been studied and monitored by the part of technical surveys of the Emilia-Romagna regional authority. Particular attention has been paid to the analysis of the evolution of landslides, acknowledging a typical, recurring succession of events that precede the failure of the slope. In general, the observation of past events has proved to be an useful mean for understanding which are the conditions and behaviours that usually lead to the reactivation of an ancient landslide body.

Sand Liquefaction Phenomena During the Seismic Crisis of May 2012 in Emilia, Northern Italy

In May 2012, the Emilia region of the Po Valley was struck by a seismic crisis with two major events of magnitude Mw 6.1 and Mw 5.9. The first event induced widespread sand blows formed along buried channels and old crevasse splay deposits. In the days immediately following the events, the detailed mapping and sampling of the erupted sand was fundamental to record all the seismically-induced phenomena. The study of a trench dug across large fractures at San Carlo (Ferrara) provided also valuable information on the sand blows mechanism and regome. The sedimentological and compositional characteristics of the fracture-filling materials indicate that the sands were erupted from a layer located between 6.8 and 7.5 m depth. Older and deeper Holocene and Pleistocene sand layers were not apparently involved in the liquefaction phenomena.