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Upgrading the 40Ar/39Ar facility at the University of Geneva

English title Upgrading the 40Ar/39Ar facility at the University of Geneva
Applicant Spikings Richard A.
Number 128146
Funding scheme R'EQUIP
Research institution Département des sciences de la Terre Université de Genève
Institution of higher education University of Geneva - GE
Main discipline Geochronology
Start/End 01.01.2010 - 31.12.2010
Approved amount 62'943.00
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Keywords (6)

40Ar/39Ar; Geochronology; Thermochronology; Tectonics; Laser; 40Ar/39Ar laboratory

Lay Summary (English)

Lead
Lay summary
We request funding for one new CO2-IR laser system, an ion pump and three scroll pumps that will be coupled with gas extraction lines and gas-source mass spectrometers that are dedicated to Ar isotopic measurements. The items will upgrade our 40Ar/39Ar facility and represent the final step to achieve complete automation of data acquisition. The 40Ar/39Ar laboratory will be used by numerous different groups within the ELSTE community (Joint School of Earth and Environmental Sciences of the Universities of Geneva and Lausanne) and beyond. These groups have a common demand to acquire 40Ar/39Ar data in current and future research proposals to achieve their aims.The 40Ar/39Ar laboratory in Geneva currently houses a single gas-source mass spectrometer (Argus), which is coupled to an old (>10 years) CO2-IR laser, and the laboratory will soon (August 2009) be housed with a second gas-source mass spectrometer (Nu Instruments; Noblesse) and its dedicated CO2-IR laser, furnace and extraction line. This transfer from the University of Lausanne to the University of Geneva has been agreed to increase the synergy within ELSTE and strengthen geo- and thermochronological activities in Geneva. The requested items will be used to i) replace the existing laser in Geneva, which has a large foot-print, is cumbersome and is not automatable, rendering data acquisition temporally inefficient, ii) replace three oil-based rotary pumps that form part of the extraction lines of both mass spectrometers with dry pumps, and iii) attach an ion-pump to the extraction line of the Argus to increase security against atmospheric contamination in the case of turbo pump failure. The mass spectrometers will operate simultaneously, and hence require individual laser systems.The new components will permit 40Ar/39Ar data to be acquired by secure, automated laser step-heating of a variety of minerals that occur in acidic igneous rocks, mafic groundmass, authigenic minerals in hydrothermal systems and compositionally immature sedimentary rocks. The data can be utilized to determine either the age, or thermal histories of those minerals, which can be used to quantify numerous geological processes, rendering the technique useful to a wide variety of geological disciplines. Numerous projects within the Section des Sciences de la Terre, University of Geneva, (see section 2.2.2) will utilize the upgraded 40Ar/39Ar facility as a tool within earth science realms such as those listed above.The upgraded 40Ar/39Ar facility will form an official part of the ELSTE community, and hence will also be readily available to staff and student members of the Faculty of Geosciences and the Environment at the U
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Associated projects

Number Title Start Funding scheme
134443 Thermochronology and Tectonics of the Northern Andes (Colombia and Ecuador) 01.04.2011 Project funding
124332 Probing lithosphere processes through geochemical and geochronological studies - Permian / Triassic intracontinental rifting and Jurassic subduction-related magmatism in Southern Peru 01.04.2009 Project funding
119871 Thermochronology and tectonics of the Northern Andes (Colombia and Ecuador) 01.04.2008 Project funding
107596 Accretionary and post-accretionary cooling, exhumation and tectonic history of the central and western Andes of Colombia 01.04.2005 Project funding

Abstract

We request funding for one new CO2-IR laser system, an ion pump and controller and three scroll (dry) pumps that will be coupled with gas extraction and purification lines, and gas-source mass spectrometers that are dedicated to Ar isotopic measurements. The proposed items will upgrade our 40Ar/39Ar facility and represent the final step to achieve complete automation of data acquisition. The application is being made by Dr Richard Spikings of the Department of Mineralogy, Section des Sciences de la Terre, University of Geneva. However, as described in section 2.2.2, the 40Ar/39Ar laboratory will be used by numerous different groups within the ELSTE community (Joint School of Earth and Environmental Sciences of the Universities of Geneva and Lausanne) and beyond. These groups have a common demand to acquire 40Ar/39Ar data in current and future research proposals to achieve their aims, as well as to reduce operator presence in the laboratory.The 40Ar/39Ar laboratory in Geneva currently houses a single gas-source mass spectrometer (Argus), which is coupled to an old (>10 years) CO2-IR laser, and the laboratory will soon (August 2009) be housed with a second gas-source mass spectrometer (Nu Instruments; Noblesse) and its dedicated CO2-IR laser, furnace and extraction line. This transfer from the University of Lausanne to the University of Geneva has been agreed to increase the synergy within ELSTE and strengthen geo- and thermochronological activities in Geneva. The requested items will be used to i) replace the existing laser in Geneva, which has a large foot-print, is cumbersome and is not automatable, rendering data acquisition temporally inefficient, ii) replace three oil-based rotary pumps that form part of the extraction lines of both mass spectrometers with dry pumps, and iii) attach an ion-pump to the extraction line of the Argus to increase security against atmospheric contamination in the case of turbo pump failure. The mass spectrometers will operate simultaneously, and hence require individual laser systems.The new components will permit 40Ar/39Ar data to be acquired by secure, automated laser step-heating of a variety of minerals that occur in acidic igneous rocks, mafic groundmass, authigenic minerals in hydrothermal systems and compositionally immature sedimentary rocks. The data can be utilized to determine either the age, or thermal histories of those minerals, which can be used to quantify numerous geological processes, rendering the technique useful to a wide variety of geological disciplines. The 40Ar/39Ar technique is used in the following geological fields (the following list is not exhaustive):-Volcanic chronostratigraphy (e.g. South America; Germany, Chile, Greenland; Renne et al., 1992; Singer et al., 1997; Storey et al., 1998).-Calibrating the magnetic and astronomical time scales (e.g. Chile, Fiji, Canary Islands, eastern Mediterranean; Baksi et al., 1993; Singer and Pringle, 1996; Clement et al., 1997; Guillou et al., 2004; Kuiper et al., 2004).-Determination of the timing of ore mineralization events (e.g. Chile, Peru; York et al., 1982; Mote et al., 2001; Phillips and Miller, 2006; Bendezú et al., 2008).-The quantification of exhumation processes related to plate collision, and the study of orogenesis (e.g. Alps, Himalayas, Andes, Rockies; Richter et al., 1991; Sherlock et al., 1999; Spikings et al., 2000, 2001a, 2005).-The study of extensional tectonics (e.g. Basin and Range Province, core complexes in New Zealand; John and Foster, 1993; Spell et al., 2000).-Analysis of the stability of continental interiors (e.g. Australia, South America, eastern Europe; Scandinavia; Foster and Ehlers 1998; Bogdanova et al., 2001; Spikings et al., 2001b, 2001c, 2002; Söderlund et al., 2009).-Determination of the thermal histories of sedimentary basins, which has applications for the petroleum industry (e.g. USA; Harrison and Bé, 1983; Mahon et al., 1998).-Fingerprinting and quantifying the exhumation histories of source regions for sedimentary basins (e.g. western USA, UK; Stuart et al., 2001; Goodge et al., 2004).-Determination of chronostratigraphic frameworks for sedimentary basins (e.g. USA, Mexico; Fulford et al., 1991; Swisher et al., 1993).-Landscape evolution studies by determining palaeo-weathering histories (e.g. USA, Africa, Brazil, Chile; Vasconcelos et al., 1994; Colin et al., 2005; Arancibia et al., 2006).Numerous projects within the Section des Sciences de la Terre, University of Geneva, (see section 2.2.2) will utilize the upgraded 40Ar/39Ar facility as a tool within earth science realms such as those listed above.The upgraded 40Ar/39Ar facility will form an official part of the ELSTE community, and hence will also be readily available to staff and student members of the Faculty of Geosciences and the Environment at the University of Lausanne, as both a teaching and research tool. The 40Ar/39Ar facility highly complements pre-existing apparatus within ELSTE because, in combination with the fission-track (Geneva) and (U-Th)/He (Lausanne) methods, it provides a full suite of thermochronological tools that will allow us to determine the thermal histories of rocks through almost the entire range of temperatures found in the earth’s middle and upper crust.
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