Upcoming report: Are the sediments of Lake Nam Co justifying any effort for an ICDP drilling project?
Presenter: Dr. Gerhard Daut, Department of Geography, University of Jena, Germany
Prof. Volkhard Spiess, Center for Marine Environmental Sciences, University of Bremen, Germany
Venue: No. 915 meeting room, ITP, Beijing
Time: 4.00 -6.00 pm, Tuesday, July 8, 2014
Moderator: Prof. ZHU Liping
Your participations are welcome!
In 2005, a joint field campaign within the Sino-German cooperation started with first shallow seismic investigations and core recoveries. Further campaigns in 2006 and 2008 extended the existing shallow seismic profiles and led to the recovery of a core covering the past 24000 years. Numerous joint publications showed that the sediments of Nam Co allow high-resolution reconstructions of the paleoclimate and environment. But the big question was: How far back in time can we get? Therefore ITPCAS, University of Bremen and University of Jena made joint efforts to carry out a deep seismic survey of Lake Nam Co. Some preliminary observation are presented here:
-The total sediment thickness may exceed several hundred meters, but confirmation of this will require more data processing.
-Comparing the Holocene, fine-grained sequence of low reflectivity with deeper seismic facies, two more units of the same signature could be observed, probably indicating quiet sedimentation conditions with sediment sources far away from the basin center, thus indicating high lake level.
-These two units have been tentatively assigned to MIS 3 and 5, the latter dating back to 125 ka in a depth of 300-350 ms TWT (two way traveltime), or appx. 150-180 m below lake floor.
-Seismic images reveal deeper, flat lying reflectors, which may well represents older, late Quaternary sediments. In the ideal case, more than 750 ms TWT of sediment may exist in the central basin, as a bedrock reflection could not yet be identified.