research interests & projects
Most of my research is focused on the application of the heavy halogens (Cl, Br and I) and noble gases (He, Ne Ar, Kr, Xe and Ar-Ar) as fingerprints of geochemical change. I apply these tracers to broad geochemical problems, from investigating the specific volatile budgets of volcanic and magmatic systems, to understanding thermal, aqueous and shock history of meteorites, to questions involving large-scale planetary geochemical evolution.
I use the NI-NGMS (Neutron Irradiation Noble Gas Mass Spectrometry) technique for halogen analysis. This method is essentially an extension of the Ar-Ar dating technique and enables not only measurement of low level (ppb-ppm) halogen concentrations in geologic samples, but can also provide information on the K, Ca, Ba, and U abundances and the Ar-Ar ages of samples. Details on the methodology can be found below and in Ruzié-Hamilton (2016). Feel free to get in touch to discuss the potential applications of NI-NGMS - details are on the Contact page.
Scroll down for details of the NI-NGMS method and for details on some of my current research projects and collaborations.
NI-NGMS
The heavy halogens (Cl, Br and I) are volatile elements that are concentrated into the Earth's surface reservoirs (e.g., sediments, hydrosphere, crust). They are present in low abundance in most geologic materials and their distribution is influenced by the presence of aqueous fluids. These factors make the halogens excellent geochemical tracers of volatile delivery, source and subsequent evolution, such as recycling at Earth's subduction zones and tracing fluid or sediment input. The NI-NGMS method enables measurement of low level (ppm Cl, pub Br and I) halogens in small (<1 mg) bulk samples. This makes the technique a good complement to in situ techniques, such as SIMS, and a particularly powerful technique when sample material is limited (such as extraterrestrial material) and a bulk halogen composition is desirable. Samples are neutron-irradiated with reference materials of known composition (typically a mix of geochronology standards for Ar-Ar and I-Xe and halogen-rich scapolite minerals - see Ruziè-Hamilton et al. 2016) to monitor the neutron flux, enabling calculation of halogen abundances from the noble-gas isotopes they are converted to during irradiation (see schematic at right). After irradiation, monitor minerals and samples are degassed by laser heating (see below right). Argon, Kr and Xe are then analyzed on a Thermo Fisher Scientific ARGUS VI at the University of Manchester and the halogen composition of samples calculated using the noble gas abundances and the irradiation parameters provided by the monitor minerals. At the University of Manchester, we use this technique to measure halogens in everything from chondrites (Clay et al. 2017), martian meteorites and lunar samples to diverse terrestrial samples, including layered intrusions (see Amy Parker's new research, Parker et al. 2019), ophiolites, metamorphic samples and experimental products.
References:
Clay, P.L., Burgess, R., Busemann, H., Ruziè-Hamilton, L., Joachim, B., Day, J.M.D., and Ballentine, C.J. (2017) Halogens in chondritic meteorites and terrestrial accretion, Nature, 551: 614-618.
Parker, A.P., Clay, P.L., Burgess, R., Balcone-Boissard, H, Bürckel, P., and O’Driscoll, B. (2019) Halogen cycling and precious metal enrichment in sub-volcanic magmatic systems: insights from the Rum layered intrusion, Scotland, Earth and Planetary Science Letters, 526, 115769. https://doi.org/10.1016/j.epsl.2019.115769
Ruziè-Hamilton, L., Clay, P.L., Burgess, R., Joachim, B., Ballentine, C.J., and Turner, G. (2016) Determination of the halogen abundances in terrestrial and extraterrestrial samples by the analysis of noble gases produced by neutron irradiation, Chemical Geology, 437: 77-87.
Schematic illustration of the neutron-gamma reaction for Br-79. Thermal and epi-thermal neutrons interact with Br-79 to form Br-80. Br-80 then undergoes beta-decay to to form Kr-80, which can easily be measured by conventional noble-gas mass spectrometry. Source: Ruzié-Hamilton et al (2016).
Laser cell loaded with samples for halogen analysis by step-wise degassing using a Teledyne-CETAC 55W CO2 laser coupled to the Thermo Fisher Scientific ARGUS VI at the University of Manchester.
HABITABILITY POTENTIAL IN ARCHEAN ENVIRONMENTS
From March 2020, I will be starting a new project using the volatile halogen (Cl, Br, I) and boron (B) elemental and isotopic signatures to understand the habitability potential of some of Earth's earliest environments. Working with collaborators Stephen Mojzsis (Univ. Colorado), Brian O'Driscoll, Romain Tartèse, Ray Burgess and Roy Wogelius (UoM), I will employ a variety of sample characterization techniques and mineral-chemical analyses to suites of Archean rocks from South Africa, Greenland and Canada to investigate a host of different environments with different formation and metamorphic histories. As halogens are concentrated in Earth' surface and track with water, a critical ingredient for early life, they are excellent tracers of crucial litho-atmos-hydro-sphere interactions on early Earth. Coupled with meteorite studies and experiments with collaborators Henner Busemann (ETH Zürich) and Bastian Joachim-Mrosko (Univ. of Innsbruck), the scope of the project will encompass investigating terrestrial volatile sources, volatile delivery processes and subsequent modification of planetary volatile budgets through large-scale processing at critical stages in Earth's history, such as differentiation.
PLANETARY VOLATILE SOURCES & BUDGETS
Volatile elements, like H, C, halogens and noble gases, are important to the physical and chemical evolution of planets, as well as the development of habitable conditions at planetary surfaces. Determining the origin, source(s) and delivery of volatiles to Earth is therefore important to understanding the early evolution of Earth and the development of life. Studying the volatile budget of meteorites, as remnants of larger asteroid parent bodies, can provide critical information on the volatile sources that were present at the time of Earth's accretion. Recent work on the halogen budget of chondrites showed that the carbonaceous, enstatite and Rumuruti chondrites have very similar halogen ratios to bulk silicate Earth. Lower absolute abundances of all the halogens further suggested that the terrestrial halogen budget can be accounted for during accretion of chondritic material. The implication of these results is that the halogens move closer in line with volatility predictions based on condensation temperatures and similar to other lithophile elements of similar volatility (image at right, Clay et al. 2017).
CI-chondrite normalized BSE concentration of the halogens (Cl, Br and I) as a function of volatility (Clay et al. 2017).
Reflected light image of a metal sulfide last in primitive EH3 chondrite ALHA 77295. Djerfisherite (dark brown central portion) is surrounded by troilite and kamacite and set in a matrix of enstatite.
Work is ongoing to characterize both primitive and differentiated meteorites, to understand volatile sources, budgets and their response to processing on parent bodies (e.g., aqueous alteration, thermal metamorphism, shock). Of particular interest is the characterization of halogen mineral carrier phases, particularly understanding which phases host Br and I. This will give a more complete picture of the halogen geochemistry of these important primitive meteorites. The image at the left shows a metal-sulfide last set in a matrix of enstatite from the primitive enstatite (EH3) chondrite ALHA 77295. The central portion is comprised of djerfisherite, a K-Cl bearing sulfide phase that is a potentially important mineral host for halogens (Clay et al. 2014). In collaboration with Henner Busemann (ETH Zürich) and Ashley King (NHM, London), halogen and noble gas studies of djerfisherite in enstatite chondrites should provide more information on this interesting sulfide.
References:
Clay, P.L., O’Driscoll, B., Upton, B.J., Busemann, H. (2014) Characteristics of djerfisherite formed in anhydrous extraterrestrial samples and fluid-rich metasomatic alkaline intrusive environments. American Mineralogist, 99:1683-1693. DOI: dx.doi.org/10.2138/am.2014.4700
Clay, P.L., Burgess, R., Busemann, H., Ruziè-Hamilton, L., Joachim, B., Day, J.M.D., and Ballentine, C.J. (2017) Halogens in chondritic meteorites and terrestrial accretion, Nature, 551: 614-618.
RBS and UV laser (213 nm and 193 nm) diffusion profiled for Ar in quartz (Clay et al. 2010).
More recently, Bastian Joachim-Mrosko's experimental work on halogen partitioning (Joachim et al. 2015, 2017) between silicate melt and important mantle minerals (see image right) has provided important insight into how the halogens partition between melt, olivine and pyroxene, as well as how halogens may be stored in these phases. In conjunction with estimates of halogen abundances from natural sample measurements, an estimate for the halogen composition of MORB and OIB source mantle can be determined using the new experimental constraints.
VOLATILE DIFFUSION, PARTITIONING & STORAGE
I started my research career in experimental petrology - conducting experiments to investigate the storage capacity, partitioning behavior and diffusive properties of the noble gases in important crustal minerals. Understanding the volatile storage capacity and transport properties of crustal and mantle minerals and melts are important to understanding important volatile sources and sinks and mechanics of volatile transport processes within the Earth. The image at the right shows how two different diffusive regimes for Ar in quartz were identified by coupling analytical techniques with different spatial resolution capabilities (Clay et al. 2010). Rutherford Backscattering Spectroscopy and UV 193 nm Excimer laser work revealed a shallow diffusive regime, whilst UV 213 nm laser work identified a deeper diffusive regime, with implications for the movement and storage of Ar in the crust (image left). Work is ongoing to quantify Ar diffusion in K-feldspar, an important crustal K-bearing mineral, with implications for Ar-Ar geochronology. Importantly, the results from experimental work can be applied to natural systems to better understand volatile storage and transport in volcanic and magmatic systems (e.g., Clay et al. 2011).
BSE image of MORB-like melt with olivine (a) and olivine and OPX grains (right) from Joachim et al. (2015).
References:
Joachim, B., Pawley, A., Marquardt, K., Lyon, I., Henkel, T., Clay, P.L., Ruzié, L., Burgess, R., Ballentine, C.J. (2015) Experimental partitioning of F, Cl and Br between forsterite, orthopyroxene and silicate melt at Earth´s mantle conditions. Chemical Geology, 416: 65-78. DOI:10.1016/j.chemgeo.2015.08.012
Joachim, B., Stechern, A., Ludwig, T., Konzett, J., Pawley, A., Ruzié-Hamilton, L., Clay, P.L., Burgess, R., and Ballentine, C.J. (2017) Effect of water on the fluorine and chlorine partitioning behavior between olivine and silicate melt. Contributions to Mineralogy and Petrology, 172 (15), 1-15. DOI 10.1007/s00410-017-1329-1
Clay, P.L., Kelley, S.P., Sherlock, S.C. and Barry, T.L. (2011) Partitioning of excess argon between alkali feldspars and glass in a volcanic system, Chemical Geology, 289, 12-30. DOI:10.1016/j.chemgeo.2011.07.005.
Clay, P.L., Baxter, E.F., Cherniak, D.J., Kelley, S.P., Thomas, J.B., and Watson, E.B. (2010) Two diffusion pathways in quartz: A combined UV-laser and RBS study, Geochimica et Cosmochimica Acta, 74, 5906-5925. DOI:10.1016/j.gca.2010.07.014