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Etude des bassins sédimentaires: A) Matière organique sédimentaire: un outil paléoécologique de haute résolution; B) Processus glaciaires anciens dans les environnements périglaciaires

English title Sedimentary basin analysis: A/ Distribution of organic matter in sedimentary environments; B/ Subglacial and periglacial processes derived from high-resolution seismic and elevation models in a perialpine setting
Applicant Gorin Georges
Number 112320
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 01.04.2006 - 31.03.2009
Approved amount 227'712.00
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Keywords (23)

amorphous organic matter; microbial mats; bacteria; miocene; lower cretaceous; upper jurassic; subglacial landforms; rib moraines; push moraines; drumlins; Lake Geneva; DNA; OAE; climate; Holocene; tropics; vegetation; glacial sediments; moraines; reservoirs; seismic stratigraphy; subglacial; Swiss Plateau

Lay Summary (English)

Lead
Lay summary
This project has addressed three aspects of sedimentary basin research:A) In the sedimentary record, sedimentary organic matter (OM) is an important constituent that can be used for the evaluation of paleoenvironments. In particular, understanding the occurrence of "amorphous" OM in sedimentary rocks has been the topics of many investigations, because this type of OM constitutes the most prolific petroleum source rocks in the world. Using high-resolution microscopic and geochemical approaches in fossil anoxic sediments and comparing these observations with present-day analogs (e.g., microbial mats), this project demonstrates that "amorphous" OM contains lots of indications of a high degree of OM preservation. The results are threefold : 1) bacteria seem to heavily contribute to OM preservation; 2) amorphous OM in oceanic anoxic events (OAE) in Central Italy results mainly from the diagenesis of benthic photosynthetic microbial mats ; 3) the existence of fossil bacterial DNA in 109myr old sediments demonstrates the exceptional OM preservation in some fossil anoxic environments.B) High-resolution palynological analyses are being carried out in anthropogenically-undisturbed, continuous LateGlacial-Holocene sediments from Northern Colombia. Changes recorded in the palynological spectrum are related with changes in vegetation belts and can be used as a proxy for climatic changes. Coupled with geochemical analyses, this investigation will produce a less-than-50yrs time resolution record of climatic variations in the tropics over the last 15'000 years. It will test climatic variability in the Holocene and identify dry/humid and warm/cold cycles in relation with variations of the Intertropical Convergence Zone (ITCZ). This project is continuing with SNF project no. 200020_124721/1.C) The study of subglacial environments relies on indirect observations, such as the study of subglacial landforms and sediments in formerly glaciated areas. This case study sheds new light on past subglacial processes in the Swiss Alpine foreland. Geomorphology and seismic stratigraphy have been used: the analysis of digital elevation models (DEM) on the Swiss Plateau evidences landforms inherited from glaciations, whereas high-resolution seismic stratigraphy in the Western Lake Geneva (Petit-Lac) highlights the subglacial sedimentary sequence accumulated in glacial valleys. These data have unravelled new aspects of glacial geology : they can be applied to model the spatial distribution of glacially-related sedimentary reservoirs, e.g. freshwater reservoirs (aquifers) or even petroleum resevoirs, or of sedimentary deposits of economic interests, e.g., gravels and sands.
Direct link to Lay Summary Last update: 21.02.2013

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Associated projects

Number Title Start Funding scheme
68091 Sedimentary basin analysis: A/ Distribution of organic matter in sedimentary environments; B/ Subglacial and periglacial processesderived from high-resolution seismic facies ... 01.10.2002 Project funding
124721 High-resolution palynology and climate change in the Late Glacial-Holocene of Colombia 01.04.2009 Project funding
124721 High-resolution palynology and climate change in the Late Glacial-Holocene of Colombia 01.04.2009 Project funding

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