RECENTLY PURCHASED ARGUS VI
July 24th, 2013
The facility uses both laser and furnace extracting system for geochronology and thermochronology applications. We can date the following minerals:
Micas – muscovite, biotite, phengite.
Feldspars – K-feldspar and plagioclase.
Whole rocks – volcanics, slates, phyllites.
Pyroxenes – e.g., found as inclusions in diamonds.
Feldspathoids – leucite, nepheline.
Clays – illite, celadonite.
Sulphates – alunite, jarosite.
Evaporites – sylvite, carnallite, polyhalite, langbeinite.
Glass – obsidian, tektites, pseudotachylite.
Manganese oxides – cryptomelane, hollandite.
Tourmaline – Shorl, Dravite, Elbaite.
Alkaline minerals – Wadeite, priderite, K-richterite.
The WAAIF is equipped with A MAP215-50 mass spectrometer with a low-blank automated extraction system coupled with a NewWave Nd-YAG dual IR (1064 nm) and UV (216 nm) laser, an electromuliplier detector and Niers source. The ultra-violet laser is capable of high-resolution (up to 10 µm beam size) ablation of any mineral, allowing detailed analysis of individual mineral grains.
The infra-red laser (continuous wavelength 60W) is capable of spot analysis (100-300 µm spot size), single grain total fusion, and incremental laser step-heating of K-rich minerals and whole rocks. For larger aliquot of minerals (> 8-10 mg) we use an automated Pond-Engineering low-blank furnace.
The facility is automated and can be controlled remotely via VNC iphone technology. The extraction line is associated with a Nitrogen cryocooler trap and two AP10 and one GP50 SAES getters that altogether allow purifying the gas released by the sample during laser heating.
The 40Ar/39Ar method is used to date a myriad of geological events such as volcanism, tectonic plate movements, mountain building rates, sediment formation, weathering and erosion, hydrothermal fluid movements, and alteration and diagenesis of minerals.
The Facility recently acquired an ARGUS VI (Thermofisher), a new generation low volume Multiple Collector Noble Gas Mass Spectrometers (MC-NG-MS) equipped with 5 faraday cups and one CDD multiplier that has recently become commercially available, offering three advantages.
Their first advantage is a better sensitivity of the new generation of CDD electron multipliers and 1012-ohm resistor faraday collectors. This allows the measurement of a larger dynamic range of Ar ion beam signal on much smaller (and thus likely purer) and younger sample aliquots.
Their second advantage is the ability to measure the 36Ar on the CDD multiplier while other masses are measured on the faraday detectors, resulting in analytical precision one order of magnitude better than with previous generation instruments.
Their third advantage is much faster sample analysis (i.e., 30-35 analyses/day compared to the current 10-12 analyses/day for single collector instruments.
A new dedicated low volume Noble Gas extraction line capable of collecting and cleaning the gas extracted from a variety of samples, using a PhotonMachine CO2 laser capable of delivering a homogenous laser beam of up to 6mm wide, is attached to the ARGUS VI mass spectrometer.
Timing of large (and small) igneous provinces (e.g., Karoo-Ferrar, Kalkarindji, Deccan, Ethiopia-Yemen, Newer volcanic province).
Timing of impact crater and structure formations (e.g., Siljan, Popigai)
Thermochronology of basaltic achondritic and chondritic meteorites and particles from asteroid Itokawa (impact history, eruption age, exposure to cosmic ray bombardment).
Technique development (e.g. the terrestrial 38Ar cosmogenic dating technique).