Wednesday, January 29, 2014

Expedition 347 Science Party at work: nice core

We are in Bremen, Germany, at the Onshore Science Party of Expedition 347. We will be processing more than 1600 m of marine sediment core over a period of 4-5 weeks. The cores were retrieved from the Baltic Sea in Sept.-Nov. 2013, which is a brackish sea enclosed by Denmark, Sweden and Finland. Some spectacular core has come up with very distinct changes in sediment color and composition. The Baltic Sea has changed multiple times from a freshwater to a brackish basin due to changes in connections to the open ocean and local sea level changes. In addition, the Scandinavian ice sheet has reached these latitudes during the last Ice Age. We see evidence of these changes in environmental conditions recorded in the cores. Some glacial clays display very nice probable seasonal laminations (varves), as you can see in the image below. We also see very sharp changes in color and sediment composition, which indicate abrupt changes in the paleoenvironment of the Baltic Sea. As sedimentologists we get to spend some time examining the cut surfaces of the cores and we record all the features we see on log sheets. More later...

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