Project

Back to overview

Integration of ground-penetrating radar, high-resolution seismic reflection and stratigraphic methods for Holocene lake-level reconstruction

English title Integration of ground-penetrating radar, high-resolution seismic reflection and stratigraphic methods for Holocene lake-level reconstruction
Applicant Beres Milan
Number 107546
Funding scheme Project funding
Research institution Département des sciences de la Terre Université de Genève
Institution of higher education University of Geneva - GE
Main discipline Geology
Start/End 01.04.2005 - 30.09.2006
Approved amount 98'952.00
Show all

Keywords (8)

Holocene; lake-level; high-resolution reflection seismic; ground-penetrating radar; facies; stratigraphy; high-resolution seismic reflection; western Switzerland

Lay Summary (English)

Lead
Lay summary
Creating environmental models of past climatic and hydrologic conditionsis often aided by records of lake-level fluctuations. By drilling andanalyzing transects of sediment cores, synchronous lake-level fluctuationsduring the Holocene (i.e. post-glacial) period have been determined inseveral French and Swiss lakes and correlated with climate-inducedpaleohydrological changes in other parts of Europe. While stratigraphicanalysis of core samples can provide models with a high time resolution,geomorphologic studies can help quantify lake-level curves and detecttopographic changes due to erosion and faulting. For example, beach ridgesand wave-cut cliffs are topographic changes that can indicate higher lakelevels.As in petroleum exploration, geomorphologic studies often rely onreflection seismic methods to generate detailed images that resemblegeologic cross-sections. In lake-level reconstructions, high-resolutionreflection seismic (HRS) methods can image small-scale erosion surfacesand sedimentary sequences and help determine the location and number ofdesired cores. Ground-penetrating radar (GPR) methods, which use thetransmission and reception of radio waves instead of seismic waves, areuncommon in lake-level studies but can be used in areas where HRS methodsare less reliable: onshore and gas-filled or coarse-grained shallow-watersediments.The aim of this project is to determine the usefulness and limitations ofGPR methods in onshore/offshore lake settings and to establish or refinelake-level curves in western Switzerland by using a combination of GPRmethods, offshore HRS methods and analysis of core transects. Due to thelarge local variations in Swiss topography and climate, combinations ofinvestigation techniques and a significant geographic coverage areparticularly necessary in reconstructing lake-levels curves and linkingthem with past climates. Understanding this link is important forultimately determining human interaction with the environment throughouthistory and prehistory.All major lakes in western Switzerland were chosen for the GPR and HRSsurveys, which used frequencies of 100-250 MHz and 3.5-kHz, respectively.Data processing was similar to that of the petroleum industry andsignificantly enhanced the accuracy and clarity of the images. LakesGeneva, Brenet and Joux were then selected for correlating the geophysicaldata with onshore/offshore core and archaeological data. Various coringmethods yielded over 50 m of sediment samples, which were analyzed forphysical properties and dated by radiocarbon methods.The results generally show continuous GPR reflections up to 5 m deep andinclined at various degrees towards the lake center. In deep water, HRSdata show penetration depth of up to nearly 50 m. Preliminaryinterpretations allow the correlation of lithologic changes withreflections, the estimation of sedimentation rates and the identificationof ancient beach deposits. A unique aspect of the project is theproduction of continuous onshore/offshore profiles, which may improve theunderstanding of lacustrine sedimentary processes.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Name Institute

Associated projects

Number Title Start Funding scheme
67082 Integration of ground-penetrating radar, high- resolution seismic reflection and stratigraphic methods for Holocene lake-level reconstruction 01.10.2002 Project funding

-