Garnet Lu-Hf Ages and Isotope Data for the Stibnite, Idaho Area
Toggle navigation. Have you forgotten your login? Journal articles. Caroline Lotout 1 AuthorId : Author. Robert Anczkiewicz 3 AuthorId : Author. Jean van den Driessche 2 AuthorId : Author. Hide details. Abstract : Linking mineral growth and time is required to unravel the evolution of metamorphic rocks. However, dating early metamorphic stages is a challenge, due to subsequent retrograde overprinting.
The Lu–Hf dating of garnets and the ages of the Alpine high-pressure metamorphism
Anczkiewicz, R. Lu-Hf geochronology and trace element distribution in garnet: Implications for uplift and exhumation of ultra-high pressure granulites in the Sudetes, SW Poland. Lithos , 95 pp. The surrounding rocks were metamorphosed at the same time as indicated by
In this paper we report garnet+omphacite±whole- rock Lu–Hf and Sm–Nd ages for five eclogites from the WGR (Fig. 1). Both methods directly date minerals.
I primarily use and develop geochemical and isotopic techniques to determine age of rocks and their origin. One of my main research fields is evolution of continental collision zones such as the Himalaya or the Carpathians. Geochronology is of my particular interest, especially means of linking isotopic ages with specific geologic events.
Recently I focus on application of isotopes to environmental and archaeological problems. Isotopic systematics and trace element partitioning under extreme conditions. Migration of mammals in Ice Age Reconstruction of migration paths of mammals during ice age by studying Sr isotopic signature and trace element record in teeth of mammoths and other animals. Publications Soldner, J.
Lokas, E. Revised Middle-Upper Jurassic strontium isotope stratigraphy. Mukhopadhyay, D. Chakraborty, S.
Garnet U-Pb and O isotopic determinations reveal a shear-zone induced hydrothermal system
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We find that the Lu/Hf ratio of garnet is particularly high, which helps to provide precise ages. Eclogites from three adjacent units of the western.
Kimberlites from Southern Africa, along with their low-Cr megacrysts, have unusual Hf—Nd isotopic characteristics. Group I kimberlites have Hf values varying from —1. Low-Cr megacryst suites from individual Group I kimberlites have compositions that overlap those of their host kimberlites. The trend for all Group I kimberlite megacrysts Hf values —1. The data indicate a genetic link between kimberlites and the low-Cr megacryst suite.
Our preferred option is that this component originates beneath the lithosphere, from a reservoir of ancient, deeply subducted oceanic basalt that became incorporated into the convecting mantle source region for Group I and Transitional kimberlites. Allegre, C. The evolution of mantle mixing. Allsop, H. A summary of radiometric dating methods applicable to kimberlites and related rocks.
Dating a single garnet crystal with very high Sm/Nd ratios (Campo basement unit, Eastern Alps)
The challenges have been largely solved for the Lu-Hf and Re-Os Duchene, S., The Lu-Hf dating of garnets and the ages of the Alpine.
Continue to access RSC content when you are not at your institution. Follow our step-by-step guide. Bast uni-muenster. When such samples are spiked, correcting for the isobaric interference of Lu on Hf is not always possible if the separation of Lu and Hf is insufficient. In addition, Sm—Nd and Rb—Sr separations can easily be added to the described two-stage ion-exchange procedure for Lu—Hf. The routine analysis of sub-ng amounts of Hf will facilitate Lu—Hf dating of low-concentration samples.
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Lu-Hf Dating: The Lu-Hf Isotope System
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The absolute crystallization ages of minerals from hydrothermal fluids measured in situ can unravel the timing of key events leading to the formation of, for instance, ore deposits and hydrothermally derived geological terrains. This skarn age instead correlates with the occurrence of strike-slip and thrust faulting in the region. The low oxygen isotopic composition indicates the role of meteoric water in the garnet formation.
Meteoric water in this hydrothermal system would leach cations from the meta-volcano-sedimentary rocks necessary for mineralization. Silica-rich hydrothermal fluid reacts with calcic-rich materials in the meta-volcano-sedimentary rocks, depositing the garnet and magnetite. Our work suggests that the shear zone is rich in ores, rendering this deposit for NW China a prospective source for future mineral resource exploration.
Garnet is an abundant mineral phase found in a range geological settings, from skarn-type ore deposits, granite, and low- and high-grade metamorphic rocks, to the upper mantle. It is a widely used proxy in geothermobarometry 1 , 2.
John Wiley and Sons Inc. Dating of the northern Idaho batholith and the Bitterroot metamorphic core complex: magmatism preceding and contemporaneous with extension. Relationships between luhf partial garnet, plutonism, orogeny, garnet exhumation: Idaho—Bitterroot Batholith. Exhumation and with of Eocene metamorphic luhf complexes along garnet Lewis and Clark strike-slip system. Frost CD, Winston D.
Dating of these processes could be achieved by garnet Sm-Nd or Lu-Hf geochronology [8,9,10]. Grandite garnet has commonly higher U and Th concentrations.
Lutetium—hafnium dating is a geochronological dating method utilizing the radioactive decay system of lutetium — to hafnium — The trace concentration of the Lu and Hf in earth materials posed some technological difficulties in using Lu—Hf dating extensively in the s. Lutetium is a rare-earth element , with one naturally-occurring stable isotope Lu and one naturally-occurring radioactive isotope Lu.
An age equation is set up for every radiometric dating technique to describe the mathematical relationship of the number of parent and daughter nuclide. The two isotopes, Lu and Hf, in the system are measured as ratio to the reference stable isotope of Hf. A common practice for geochronological dating is to establish an isochron plot. According to the Goldschmidt classification scheme, Lu and Hf are both lithophile earth-loving elements, meaning they are mainly found in the silicate fraction of Earth, i.
Both Lu and Hf are incompatible trace elements and relatively immobile. The original figure 9 from Rehman et al. The chondritic uniform reservoir model age is the age at which the material, from which rock and mineral forms, leaves the chondritic uniform reservoir, i. The chondritic uniform reservoir model are tightly constrained in order to use Lu—Hf system for age determination. In the earliest years, at around the s, age acquisition based on Lu—Hf system make use of chemical dissolution of sample and thermal ionization mass spectrometry TIMS.
The above sample preparation procedures prevent convenient analysis of Lu—Hf, thus limiting its usage in the s. Selective dissolution, i.
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In lu and hf, texas, korsakov, have been dated using. Dating studies. Find single man in lu and geophysics, mn will link important in garnet. State university. The lu-hf system.
Lu-Hf garnet dating provides high precision age information, which is competitive even for the most precise geochronometers. Accuracy of garnet geochronology.
Gonzaga, M. Menzies, M. Thirlwall, D. Jacob, A. Cratonic eclogites and garnet pyroxenites from the Kaapvaal craton have heterogeneous Hf—Nd—Sr— O isotope ratios that define a positive Hf—Nd isotope array and a negative Nd—Sr isotope array. Isotopic variability encompasses depleted mid-ocean ridge basalt and ocean-island basalt to enriched mantle compositions Group I and II kimberlites and overlaps with that of the Kaapvaal craton garnet peridotite xenoliths.
Much of this similarity may well be due to partial or complete resetting during entrainment. Kaapvaal and emplacement in orogenic belts e. Beni Bousera.
Portsmouth Research Portal. Bird M. Thirlwall Professor Rob Strachan C. Caledonian orogenesis in Scotland is currently interpreted in terms of a Mid-Ordovician arc—continent collision Grampian event followed by the Silurian collision of Laurentia with Baltica Scandian event. Lu—Hf and Sm—Nd garnet ages of c. Lu—Hf and Sm—Nd ages of c.
The high Lu/Hf ratios found in garnets make these minerals useful for Lu–Hf dating of metamorphic events. Eclogites from three units of the western Alps give.
The Lu-Hf isotope system, with applications to geo- and cosmochemistry, was first investigated in the early s Patchett b ; Patchett and Tatsumoto a, b , c , following the successful implementation of the Rb-Sr and Sm-Nd isotope systems several years earlier. There are some obvious similarities between the Lu-Hf and Sm-Nd isotope systems and, as a result, they have long been used in concert in a wide range of studies e.
In these two systems all elements are lithophile and refractory with high condensation temperatures. Because of these characteristics it has long been assumed that their abundances in the Earth can be approximated by chondritic meteorites see discussion below. In addition, all elements in these systems behave incompatibly during melting and are concentrated in the melt over the residual solid. In both systems, the daughter element e. Both Lu and Hf are highly immobile and insoluble and, as is the case with the Sm-Nd system, are thought to be resistant to perturbations and retain their isotopic information through significant degrees of alteration and metamorphism.