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Cauca-Lift: Uplift in the Caucasus Mountains - Insights from very low Temperature thermochronometry and in cosmogenic dating

English title Cauca-Lift: Uplift in the Caucasus Mountains - Insights from very low Temperature thermochronometry and in cosmogenic dating
Applicant Ruiz Geoffrey
Number 126427
Funding scheme Ambizione
Research institution Institut de Minéralogie et Géochimie Université de Lausanne
Institution of higher education University of Lausanne - LA
Main discipline Geology
Start/End 01.02.2010 - 31.01.2013
Approved amount 429'288.00
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All Disciplines (4)

Discipline
Geology
Other disciplines of Earth Sciences
Geochronology
Geochemistry

Keywords (26)

thermochronology; processes; fault; long versus short term; denudation; climate; Russia; Georgia; Azerbaijan; oil; geodynamics; accommodation; Uplift; Caucasus; Erosion; Exhumation; Arabia; Eurasia; Caspian; Tectonics; (U-Th)/He ; Fission-Track ; cosmogenic; noble gas ; source; sink

Lay Summary (English)

Lead
After three years, this ambizione project untitled CAUCA-Lift allowed me to organize two field trips, i.e. one in Georgia (2010) and one in Russia (2012). The goal of these two campaigns was collect samples for low-temperature analyses along a transect localized in the Central Caucasus. Results indicate that the hanging walls of the Great and Lesser Caucasus undergo important exhumation since the Late Miocene-Pliocene.
Lay summary

The project CAUCA-Lift aimed at quantifying the orogenic growth of the Caucasus Mountains. The target area was the ESE- WNW oriented Caucasus range bordered by the Caspian and Black sea basins. It is a key natural laboratory: this region is characterized by spatially heterogeneous present-day plate tectonic movements along the chain (GPS and earthquakes) - pushed by the convergence between Arabia and Eurasia. The Main Caucasus (MCT) - South Caucasus (SCT) Thrust system together with the North Caucasus Front (NCF) and Thrust (NCT) accommodate much of the horizontal shortening and associated uplift of the Great-Caucasus (GC) over the Lesser-Caucasus and Scythian platform respectively. Phases of shortening, uplift and exhumation were poorly constrained, and there is little quantitative data available on the orogen itself that contrasts wit the wealth of subsidence analysis in the bordering oil-productive basins.

            The presence of high topography in the GC was subject to debate because little is known about phases of uplift. Orography: there is a marked contrast in the slope gradient from one side to the other in the Greater Caucasus, at least in its easternmost segment where convergence reaches 14 mm/y, i.e. high towards the orogenic front to the SSW and lower on the other side of the range towards the NNW in Dagestan.

            For all these reasons we determine rates of vertical movements along a transect across and along the Caucasus chain by the use of low temperature thermochronology (Fission-Track and (U-Th)/He dating). Our sampling profiles were selected across the main faults and the highest topographic elevations, in order to obtain the best controls on denudation histories and relief evolution within the different morpho-structural domains of the belt. Our results are derived from 25 samples and provide key elements for the quantification of denudationr rates. Apatite fission-Track ages span bewteen 120 and 15 Ma whereas U-Th/He dating on 1) apatite are all younger than 7 Ma while 2) zircon are comprised between 180 and 2 Ma. Contrasts are important and indicate that the Caucasus does not exhume as a whole. Once these three datasets combined together I can evidence that the active fault systems along which the Caucasus undergoes a recent phase of uplif are the South Caucasus Front and Fault. Additional thermal modelling is on its way to refine phases of iplift. I constrain denudation for the uppermost 1-8 km, i.e. rates of medium to long-term processes. U-Th/He data as young as 2 Ma suggest that rates reach 3 km/my which is very fast. This combination of methodologies allowed the detection of secular changes in denudation rates to be investigated from geological to sub-recent time and thanks to the prolongation I obtained I am convinced that I will be able to draw maps of rapid uplif.

            Our dataset is the first one of this kind produced across the Caucasus chain. First order results constrain and distinguish phases of orogenic growth. For these rasons I also compared these thermochronlogical results to existing geological records such as foreland basin infillings provided by some of my local collaborators. The ultimate goal is partially attained, i.e. understand why the Great Caucasus undergoes today rapid uplift while sismic and GPS. The relevant tectonic processes that shaped the landscape of this mountain range in the frame of the Arabia-Eurasia convergence are the convergence itself that generated the thrusting of the Great Caucasus onto the foreland basins.

Direct link to Lay Summary Last update: 28.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Evidence for mantle exhumation along the Arabian margin in the Zagros (Kermanshah area, Iran) in Lithosphere dynamics and sedimentary basins: the Arabian plate and analogues
Wrobel-Daveau Jean-Christophe, Ringenbach Jean-Claude, Tavakoli Said, Ruiz Geoffrey, Masse Pierre, Frizon de Lamotte Dominique, Evidence for mantle exhumation along the Arabian margin in the Zagros (Kermanshah area, Iran) in Lithosphere dynamics and sedimentary basins: the Arabian plate and analogues, in Arabian Journal of Earth Sciences, Special Volume, 3(4), 499-513.
From central atlantic rift to Neogene uplift – western Anti-Atlas Morocco.
geoffrey ruiz, From central atlantic rift to Neogene uplift – western Anti-Atlas Morocco., in terra nova, 23, 25-41.
Late Triassic–early Jurassic block tilting along E–W faults, in southern Tunisia: New interpretation of the Tebaga of Medenine
camille raulin, Late Triassic–early Jurassic block tilting along E–W faults, in southern Tunisia: New interpretation of the Tebaga of Medenine, in Journal of African Earth Sciences, 61, 94-104.

Collaboration

Group / person Country
Types of collaboration
Apatite SA. United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
Geological Survey of Greenland and Denmark Denmark (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Tbilisi State University Georgia (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Industry/business/other use-inspired collaboration

Communication with the public

Communication Title Media Place Year
Talks/events/exhibitions exposés/présentations/événements, The Atlas mounains: why there? Why now? Western Switzerland 2010
Talks/events/exhibitions exposés/présentations/événements, Detrittal thermochronology: what do we truly trace? Western Switzerland International German-speaking Switzerland 2010
Talks/events/exhibitions exposés/présentations/événements, Thermochronologie de basse temperature: implications et applicatio Western Switzerland International 2010

Associated projects

Number Title Start Funding scheme
110973 The Eastern Great Caucasus: geodynamics of an active mountain belt at the cross-road of Europe, Middle-East and Asia 01.01.2006 SCOPES
145222 Cauca-Lift: Uplift in the Caucasus Mountains - Insights from very low Temperature thermochronometry and in cosmogenic dating 01.02.2013 Ambizione

Abstract

The proposed project aims at quantifying the orogenic growth of the Caucasus Mountains. The target area is the ESE- WNW oriented Caucasus range bordered by the Caspian and Black sea basins. It is a key natural laboratory: this region is characterized by spatially heterogeneous present-day plate tectonic movements along the chain (GPS and earthquakes) - pushed by the convergence between Arabia and Eurasia. The Main Caucasus (MCT) - South Caucasus (SCT) Thrust system together with the North Caucasus Front (NCF) and Thrust (NCT) accommodate much of the horizontal shortening and associated uplift of the Great-Caucasus (GC) over the Lesser-Caucasus and Scythian platform respectively. Phases of shortening, uplift and exhumation are poorly constrained, and there is little quantitative data available on the orogen itself that contrasts wit the wealth of subsidence analysis in the bordering oil-productive basins.The presence of high topography in the GC is subject to debate because little is known about phases of uplift. Orography: there is a marked contrast in the slope gradient from one side to the other in the Greater Caucasus, at least in its easternmost segment where convergence reaches 14 mm/y, i.e. high towards the orogenic front to the SSW and lower on the other side of the range towards the NNW in Dagestan.Here, we propose to determine rates of vertical movements along three different transects across and along the Caucasus chain by the combined use of in situ cosmogenic dating and low temperature thermochronology (Fission-Track and (U-Th)/He dating). Our sampling profiles will span across the main faults and the highest topographic elevations, in order to obtain the best controls on denudation histories and relief evolution within the different morpho-structural domains of the belt. Our results will provide key elements for the quantification of denudation rates in relation with tectonic and possible climatic (glaciation) forcing. Cosmogenic nuclides in present-day fluvial sediments will be used to constrain (sub-)recent erosion rates. The (U-Th)/He and Fission-Track thermochronometry will provide quantitative insight into the denudation of the uppermost 1-8 km, i.e. rates of medium to long-term processes. This combination of methodologies allows the detection of eventual secular changes in denudation rates to be investigated from geological to sub-recent time.Our dataset will be the first one of this kind produced across the Caucasus chain. First order results of the study will help to constrain and distinguish phases of orogenic growth. Comparing these results to existing geological records will enable us to identify and quantify the relevant tectonic process that shaped the landscape of this mountain range in the frame of the Arabia-Eurasia convergence. This project will thus [1] bring substantial new data on major vertical movements that took place in the Greater and Lesser Caucasus regions, [2] provide insight into the question of how the orogenic growth evolved, and more generally [3] provide an important resource to Geoscientists for studying the long and short-term geodynamics of the Caucasus mountains.
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