Events

Public Lecture by Australian Sedimentologist, Dr Craig Sloss

Summary

Underwater river of sand & mud: a five million year history of climate change, tectonics & currents

Start Date

5th Mar 2012 6:00pm

End Date

5th Mar 2012 7:00pm

Venue

Life Sciences Lecture Theatre 1, Building 34, Sandy Bay campus

RSVP / Contact Information

RSVP - E:UTAS.Events@utas.edu.au; T: 6226 2521

A free public lecture by

Dr Craig Sloss

School of Earth and Environmental Science
Queensland University of Technology

on

Underwater river of sand and mud:
a five million year history of climate change, tectonics and ocean currents in the Gulf of Cádiz
west of the Strait of Gibraltar
 
About the speaker

Craig Sloss is an Australian sedimentologist who took part in a recent expedition of the Integrated Ocean Drilling Program, which drilled a number of fully cored holes in the thick sequence of sediments deposited where the Mediterranean outflow current and other ocean currents have been active over the last 5 million years. These sediments will reveal a great deal about global events, including the tectonic and sea level fluctuations affecting the Straits of Gibraltar, and the glacial and interglacial phases of the last 2 million years.

He writes “As a sedimentologist on IODP Expedition 339, I am involved in research into sedimentological characteristics, facies description and interpretation of process involved in the along and down slope depositional systems. This will include detailed investigation of the geologically recent contourite deposits laid down over the last glacial cycle of 300,000 years.”

Abstract

Craig R. Sloss, F Javier Hernandez-Molina, Dorrik Stow, Carlos Alvarez-Zarikian and Expedition IODP 339 Scientists.

The world’s oceans are far from static. Many large currents flow at various depths beneath the surface and, together, these currents form a global conveyer belt that transfers heat energy around the globe and helps buffer Earth’s climate from the extremes. Critical gateways in the ocean affect circulation of these major currents. The Strait of Gibraltar is one such gateway, which re-opened 5.3 million years ago after being isolated from the Atlantic for several hundred millennia.

Today, deep below the surface, there is a powerful cascade of Mediterranean water spilling out through the Strait into the Atlantic Ocean. Because this water is saltier than the Atlantic – and therefore heavier – it plunges more than 1000 metres down slope, scouring the rocky seafloor, carving deep-sea canyons and building up mountains of mud on a little known submarine landscape. These sediments hold a record of climate change tectonic activity and deep sea currents that spans much of the past 5.3 million years.

IODP Expedition 339 drilled 5 sites in the Gulf of Cádiz and 2 off the west Iberian margin, from November 2011 to January 2012. The total length of core recovered was 5447 m, with an average recovery of 86.4%. The Gulf of Cádiz was targeted for drilling as a key location for the investigation of Mediterranean Outflow Water (MOW) through the Gibraltar Gateway and its influence on global circulation and climate. It is also a prime area for understanding the effects of tectonic activity on evolution of the Gibraltar Gateway and on margin sedimentation. Results show that sedimentary depositional environments along the middle continental slope (500-1200 metres deep) were strongly influenced by the opening of the Strait. The sedimentary successions include those laid by down slope processes such as turbidity currents and mass movement.

However, the depositional environment is dominated by along slope processes which have resulted in one of the most extensive contourite depositional systems (CDS) ever described. The high sedimentation rates and expanded sedimentary records of CDS permit high-resolution examination of the influence of the opening of the Gibraltar Gateway, the MOW, climate change and the interaction of a variety of down slope and along slope processes on sedimentary successions. Preliminary results also show a remarkable record of orbital-scale variation in bulk sediment properties of contourites at several of the drift sites and a good correlation between all sites. The climate control on contourite sedimentation is clearly significant at this scale; further work will determine the nature of controls at the millennial scale.

  

Talk and questions 6 - 7 pm, followed by light refreshments and further discussion until 7.30 pm.

The Life Sciences Lecture Theatre 1 is accessed via the pedestrian overpass from the University Centre car park.  Campus maps can be accessed from the Quick Links on this page.

 

Present by the Institute for Marine and Antarctic Studies.