Downes, Hilary and de Vries, C. International Journal of Earth Sciences 1 , pp. ISSN Clinopyroxenes in some fresh anhydrous spinel peridotite mantle xenoliths from the northern Massif Central France and Lower Silesia Poland , analysed for a range of incompatible trace elements by laser ablation inductively coupled plasma mass spectrometry, show unusually strong negative anomalies in Hf and Zr relative to adjacent elements Sm and Nd, on primitive mantle-normalised diagrams. Similar Zr—Hf anomalies have only rarely been reported from clinopyroxene in spinel peridotite mantle xenoliths worldwide, and most are not as strong as the examples reported here. Nevertheless, some mantle xenoliths from Poland or the Czech Republic may be amenable to Hf-isotope dating in the future. Additional statistics are available via IRStats2.
Lu hf garnet dating usa laboratory
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Two garnet-bearing granulites from Kilbourne Hole have extreme Lu Hf ratios of and (Lu Hf ≈ 28 and 39 × chondritic), but.
Author contributions: T. Yet the data interpretation requires a well-defined hafnium isotope growth curve of the bulk Earth, which is notoriously difficult to reconstruct from the variable bulk compositions of undifferentiated chondrite meteorites. Here we use lutetium—hafnium systematics of meteorite zircon crystals to define the initial hafnium isotope composition of the Solar System and further to identify pristine chondrites that are the best representative of the lutetium—hafnium system of the bulk Earth.
Knowledge of planetary differentiation is crucial for understanding the chemical and thermal evolution of terrestrial planets. However, these ratios in chondrites are highly variable due to the metamorphic redistribution of Lu and Hf, making it difficult to ascertain the correct reference values for the bulk Earth. In addition, it has been proposed that chondrites contain excess Hf due to the accelerated decay of Lu resulting from photoexcitation to a short-lived isomer.
Coherence of the Dabie Shan UHPM terrane investigated by Lu-Hf and 40Ar/39Ar dating of eclogites
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The challenges have been largely solved for the Lu-Hf and Re-Os systems Re-Os geochronology has proved useful in dating the formation of.
Jingao Liu, D. Alard, O. Project : Research. N2 – Highly depleted Archean peridotites have proven very amenable to Re-Os model age dating. In contrast, due to the increasing heterogeneity of mantle Os isotope compositions with time, the Re-Os system has not been as effective in dating post-Archean peridotites. The timing of depletion and accretion of post-Archean lithospheric mantle around cratons is important to understand within the context of the evolution of the continents.
In an attempt to precisely date post-Archean peridotite xenoliths, we present a study of the petrology, mineralogy and geochemistry, including whole-rock Re-Os isotopes, highly siderophile elements and clinopyroxene-orthopyroxene Sr-Nd-Hf isotopes of peridotite xenoliths from Lake Nyos in the Cameroon Volcanic Line CVL. Eight Nyos peridotite xenoliths, all fresh spinel lherzolites, are characterized by low to moderate olivine Fo contents However, trace element patterns of both clinopyroxene and orthopyroxene are not a pristine reflection of melt depletion but instead show various extents of evidence of metasomatic enrichment.
Because of these metasomatic effects, the Sr-Nd isotope systematics in pyroxenes cannot sufficiently reflect melt depletion signatures. Unlike Sr-Nd isotopes, the Lu-Hf isotope system is less sensitive to recent metasomatic overprinting. The reconstructed Nyos Lu-Hf isochron from ortho- and clinopyroxenes gives an age of 2. With regards to the origin of the CVL, our data reveal that the Hf isotopic compositions of the Nyos peridotites are too radiogenic to be the main source of the CVL basalts.
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Lu-Hf Dating: The Lu-Hf Isotope System
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Lu-Hf and Sm-Nd garnet geochronology: chronometric closure and implications for dating petrological processes. / Smit, Matthijs Arjen; Scherer, Erik E.; Mezger.
Lu-Hf Dating Method Lu – Hf method. Eclogites from three units of the. Re-Os geochronology has proved used full in dating the formation of iron meteorites,. Appropriate material for Lu — Hf dating. Usage analogous to the Sm—Nd method. Uranium gry dating :. The uranium-thorium method is often helpful for dating luhf in the 40, to ,year-old range, too old for radiocarbon but too young for K-Ar or.
A summary of radiometric dating methods applicable to kimberlites and related.
Extending In-Situ Dating to New Geochronometers: Pb-Pb, Sm-Nd, Re-Os, and LuHf
Journal of Earth Science, , 18 3 : Journal of Earth Science , , 18 3 : Article views PDF downloads Cited by. The group has been considered as the syn-orogenic product of the Baoshan with Simao-Indochina blocks. However, its depositional time and provenance remain to be poorly constrained.
Lu-Hf dating, petrography, and tectonic implications of the youngest Alpine eclogites (Tauern Window, Austria). Publikation: Bidrag til tidsskrift/Konferencebidrag.
Two episodes of different age and genesis have been identified. Hf isotope signature of the units indicates mantle sources as well as crustal components. The tectonic setting and age of the Gondwanan magmatism in NW Argentina allow to differentiate: a. Permian intra-plate magmatism developed under similar conditions to the upper section of the Choiyoi magmatism exposed in the Frontal Cordillera and San Rafael Block, Argentina; b.
Triassic magmatism belonging to a poorly known subduction-related magmatic arc segment of mostly NS trend with evidence of porphyry type mineralization in Chile, allowing to extend this metallotect into Argentina. It comprises epizonal plutonic and volcanic rocks, the latter including pyroclastic facies. In Argentina and Chile the assemblage has been named Choiyoi magmatic province Kay et al.
ABSTRACT. Lu–Hf isotope system and Sr–Nd–Hf–Os isotope systematics of mantle rocks is capable to unravel the early processes in collision.
This data includes U — Pb geochronology and Lu — Hf analyses from over zircons and Sm—Nd, Sr and Pb isotopic geochemistry from 14 whole-rock granitoid samples. U — Pb data were obtained during nine sessions along with common zircon reference materials e. Lu — Hf data were obtained during three sessions along with common zircon reference materials e. Each of the four whole-rock isotopes were measured for all samples in one TIMS analytic run. Twenty-nine granitoid samples in total are used for this study.
The individual sample locations, lithology, associated granitoid belt where applicable and analysis method for each sample are outlined in Table 1 of .