PP21B-2224
Understanding the Miocene-Pliocene – The Mediterranean Point of View

Tuesday, 15 December 2015
Poster Hall (Moscone South)
Dirk Simon1, Alice Marzocchi2, Dan John Lunt2, Rachel Flecker2, Frits J Hilgen3 and Paul Th Meijer4, (1)Utrecht University, Utrecht, 3584, Netherlands, (2)University of Bristol, Bristol, United Kingdom, (3)Utrecht University, Stratigraphy and Paleontology, Utrecht, Netherlands, (4)Utrecht University, Utrecht, Netherlands
Abstract:
During the Miocene-Pliocene the Mediterranean region experienced major changes in paleogeography. Today, its only connection to the global ocean is the Strait of Gibraltar. This restricted nature causes the Mediterranean basin to react more sensitive to climatic and tectonic related phenomena than the global ocean: Not just eustatic sea-level and regional river run-off, but also gateway tectonics and connectivity between sub-basins are leaving an enhanced fingerprint in its geological record. To understand its evolution, it is crucial to understand how these different effects are coupled.

The Miocene-Pliocene sedimentary record of the Mediterranean alternates in composition and colour. Around the Miocene-Pliocene Boundary the most extreme changes occur in the Mediterranean Sea: About 6% of the salt in the global ocean got deposited in the Mediterranean Region, forming an approximately 2km thick salt layer, which is still present today. This extreme event is named the Messinian Salinity Crisis (MSC, 5.97-5.33Ma).

Before (and also after) the MSC, the sedimentary record demonstrates “marl dominated” alternations with variations in organic content (e.g. higher organic content = sapropel). During the MSC these change to mainly “evaporite (e.g. gypsum or halite) dominated” alternations, but also to brackish Black Sea-type of deposits towards the end of the crisis. Due to its relative short geological time span, the period before, during and after the MSC is ideal to study these extreme changes in sedimentation.

We are investigating these couplings and evolutions in a box/budget model. With such a model we can study the responses to basin water exchange dynamics under the effect of different regional and global climatic and tectonic forcings, to predict the evolution of basin properties (e.g. salinity). By doing so we can isolate certain climatic and tectonic effects, to better understand their individual contribution, their interaction, but also the consequences due to their coupling.

Keywords: Mediterranean Sea, Climate, Coupling, Evolution, Messinian Salinity Crisis, Modeling, Strait of Gibraltar, GCM

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