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U-Pb Geochronology

Chemical analyses show that rutile included in other minerals Rt inc commonly show higher SiO 2 and FeO contents and lower Nb 2 O 3 and ZrO 2 contents if compared with rutile in the matrix of the garnet-rich layer Rt mat. Cr 2 O 3 concentrations are quite similar in both types of rutile. Rt mat commonly shows a greater variability in minor elements, especially Nb 2 O 3 0. Few compilations of geochemical and geochronological data on rutile in Variscan metabasites can be found in literature, thus these data represent a new insight on a mineral phase the significance and scientific interest of which are rising in the last years.

Allanite U-Pb ages together with the petrographic support can provide the time of the peak metamorphism (Kim et al. ). Rutile is the most common TiO2.

Metrics details. These sampled both oceanic brecciated material and a blackwall reaction zone in contact with a micaschist and serpentinized peridotite. Textural observations combined with new geochronological data indicate that rutile and titanite both grew below their closure temperatures during Alpine metamorphism. We present a technique to calculate the most precise and accurate ages possible using a two-dimensional U—Pb isochron on a Wetherill concordia. Rutile from two samples gave a U—Pb isochron age of Titanite from three samples gave a U—Pb isochron age of This age is consistent with Rb—Sr isochron ages on mylonites along and in the footwall of the Lunghin—Mortirolo movement zone, a major boundary that separates ductile deformation in the footwall from mostly localized and brittle deformation in the hangingwall.

Rubatto In the past decade, U—Pb geochronology of other accessory minerals has attracted increasing interest, with the growing recognition that in metamorphic contexts they may record a different part of the P—T evolution from zircon e. Engi ; Kohn ; Zack and Kooijman However, U—Pb dating of moderate- to low-temperature metamorphic overprints or retrogression is notoriously difficult e.

Geochemical and geochronological dataset of rutile from a Variscan metabasite in Sardinia, Italy

High-precision U-Pb dating of accessory minerals to resolve timescales of geological processes. Or Triton TIMS was purchased from Thermo Scientific in and has been reliably serving for precise isotope ratio determination since then. The amplifiers of the 10 faraday cups were initially equipped with 5 1E12 Ohm, and 5 1E12 Ohm resistors. The 5 aplifiers with 1E12 Ohm resistors have now been replaced by 1E13 Ohm resistors, together with the respective gain calibration board and new software to allow for the tau correction.

Pb ages and no U–Pb ages. Therefore the potential of LA-. MC-ICPMS to rutile U​–Pb dating has not been fully ex- plored. We hereby report a new analytical.

To browse Academia. Skip to main content. Log In Sign Up. Download Free PDF. Richard Hinton. Elena Belousova. Matthias Barth. Thomas Zack. George Luvizotto. Melissa Wolfe. Employing a nm stable detrital heavy minerals in sedimentary rocks. Rutile thermometry of Becherweg 21, Mainz, Germany the same detrital grains indicates former granulite-facies e-mail: zack uni-mainz.

Rutile U-Pb Geochronology

Help Contact us. Bracciali, Laura. Geosciences , 9 The significant and continuous improvement of instrumentation and approaches has opened new fields of applications by extending the range of minerals that can be dated by this method. Following the development and distribution to the community of good quality reference materials in the last decade, rutile U-Pb thermochronology with a precision only slightly worse than zircon has become a commonly used method to track cooling of deep-seated rocks.

LA-ICP-MS U–Pb dating of detrital rutile and zircon from the Reynolds Range: A window into the Palaeoproterozoic tectonosedimentary evolution of the North.

This paper presents new data related to the emplacement ages of the Amakinskaya and Taezhnaya kimberlites of the Mirny field, Siberia, located in the southern part of the Yakutian diamondiferous province. This study analyzed rutile and titanite grains along with zircons for U-Pb isotope composition by laser ablation LA -inductively coupled plasma-mass spectrometry ICP-MS and evaluated the applicability of rutile and titanite for the dating of kimberlite emplacements.

Both minerals contain substantial admixtures of common Pb in their Pb isotope composition. Therefore, the Pb method was applied for common Pb correction during age calculation. All age estimates correspond to the main epoch of diamondiferous kimberlite activity in the Siberian platform and suggest the formation of the Mirny kimberlite field within a single event or two separate events occurring close together in time.

Results obtained from this study indicate that rutile and titanite can be useful for the dating of kimberlite emplacements. Agashev V. Pokhilenko V.

In situ U-Pb rutile dating by LA-ICP-MS

We implement several procedures that help combat these analytical issues. Pb and U. To decrease molecular interferences at Pb peaks and increase the signal:noise ratio, we also use the energy filter to only accept high-energy ions into the collector. Because common lead and the amount of molecular interferences vary by sample, energy filtering is not always used. Grey shaded area outlined in black represents published age of standard measured by TIMS Luvizotto et al. Individual rutile U-Pb analyses typically take minutes per spot.

U-Pb dating of rutile R using LA–. ICP–MS and monazite U–Pb geochronometers, makes rutile a highly suitable mineral for the. 25 reconstruction of.

Abstract In situ laser ablation ICP-MS U—Pb dating of metamorphic rutile from granulite facies metapelitic rocks of the Archaean Pikwitonei granulite domain Manitoba, Canada provides constraints on Pb diffusion and characterizes the closure behavior of rutile. Age profiles indicate that volume diffusion of Pb occurs in rutile implying that the ages represent cooling ages. To investigate the closure behavior of Pb in rutile closure temperature profiles T c x were constructed based on different models combined with experimentally-determined diffusion parameters.

The classical T c x model of Dodson ; Mat. Forum 7, — indicates a rapid decrease of T c in the rims of grains, providing unrealistic estimates for the cooling rate when combined with U—Pb ages. A new T c x model was constructed based on the analyzed age profiles that are described by an error function. This model shows a more steady decrease in T c throughout the grain from ca. The new model provides a better description of the relation between age and T c for the analyzed grains.

However, both T c x models demonstrate that even in small grains the variations of T c can be significant making it impossible to derive one representative T c for Pb in rutile. The error function-based T c x model allows the determination of cooling rates, which show a decrease over time from ca. This consistency supports the validity of our model and indicates that cooling rates can be estimated from single grains by LA-ICP-MS U—Pb dating of rutile providing constraints on the cooling history of a metamorphic terrane.

In situ laser ablation ICP-MS U-Pb dating of metamorphic rutile from granulite facies metapelitic rocks of the Archaean Pikwitonei granulite domain Manitoba, Canada provides constraints on Pb diffusion and characterizes the closure behavior of rutile. To investigate the closure behavior of Pb in rutile closure temperature profiles Tc x were constructed based on different models combined with experimentally-determined diffusion parameters. The classical Tc x model of Dodson ; Mat.

Time resolved rutile U/Pb data derived from LA-ICPMS – a case study from the North Pamir

Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. DOI: Schmitt and T.

Abstract/Summary. U-Pb dating by LA ICP-MS is one of the most popular and successful isotopic techniques available to the Earth Sciences to.

Storey, Martin Smith , T. N2 – In situ U—Pb dating of a variety of mineral phases is an important goal in petrology. This study reports data chiefly from titanite, but also from rutile and apatite, obtained using the laser ablation LA -ICP-MS methodology on polished thick sections in order to retain as much petrologic information as possible, and allowing trace element analyses from adjacent areas to the U—Pb analyses.

The samples analysed come from Svecofennian intermediate to acid volcanic rocks of the Porphyry Group within the major iron ore province of Norrbotten, northern Sweden, where titanite is a common phase associated with the mineralisation. However, the data are a priori accurate as they are geologically reasonable. Apatite shows reverse discordance, which could be explained by a number of scenarios. The titanite grains studied show complex internal structures. Rare earth element REE analysis by LA-ICP-MS demonstrates that the core and rim zones are distinct and supports a model for two-stage evolution in two out of three samples, with the rims in these samples being enriched in total REE, and particularly in LREE in one sample, and displaying a positive Y-anomaly in contrast to the cores.

In situ U—Pb analysis reveals that core zones from all samples retain distinct older ages of c. In both cases, the ages are consistent with previous age determinations from the Fe oxide—apatite deposits. A sample from Malmberget records a slightly different scenario, where U—Pb ages spread along concordia from c. We attribute this pattern to metamorphic reworking of primary metasomatic titanite. Rutile ages from inclusions within the core of Gruvberget titanite essentially mimic the ages obtained from the surrounding titanite and suggest that they have undergone the same history.

These data indicate that the Porphyry Group volcanics must be at least c.

U-Pb LA-ICPMS dating using accessory mineral standards with variable common Pb

Providing customized analytical solutions at the highest standards of quality assurance and quality control. Samples for U-Pb dating are processed using a Rhino jaw crusher, a Bico disk grinder equipped with ceramic grinding plates, and a Wilfley wet shaker table equipped with a machined Plexiglass top, followed by conventional heavy liquid and magnetic separation using a Frantz magnetic separator. Four binocular microscope workstations are available for sample picking.

The external morphology of mineral grains for analysis can be documented by SEM, and internal structure can be examined in polished grain mounts by cathodoluminescence imaging.

Employing a nm Nd:YAG laser coupled to a quadrupole ICP-MS and using R10 as a primary standard, rutile U/Pb concordia ages for the two.

Stockli, George L. Luvizotto, Matthias G. Barth, Elena Belousova , Melissa R. Wolfe, Richard W. Rutile is a common accessory mineral that occurs in a wide spectrum of metamorphic rocks, such as in blueschists, eclogites, and granulites and as one of the most stable detrital heavy minerals in sedimentary rocks.

The advent of rutile trace element thermometry has generated increased interest in a better understanding of rutile formation. Rutile thermometry of the same detrital grains indicates former granulite-facies conditions. The methods outlined in this paper should find wide application in studies that require age information of single spots, e.

Box , Beijing , P. E-mail: xieliewen mail. The advantages include high spatial resolution, high sample throughput, good precision and accuracy, and limited sample preparation. For the application of these techniques in U—Th—Pb geochronology, the main challenges involve ion counter drift, matrix differences between reference materials and samples, laser-induced downhole elemental fractionation and common lead corrections.

Age of Mirny field kimberlites (Siberia) and application of rutile and titanite for U-​Pb dating of kimberlite emplacement by LA-ICP-MS. A. M. Agashev, Y. Orihashi.

This study investigates Ti mobility in the presence of halogens, as shown by the hydrothermal alteration of magmatic rutile in syenite. The syenite pegmatite studied intrudes gabbro, is preserved as a tectonic block in a major strike-slip fault zone, and formed in a back-arc environment in which there was widespread A-type granite plutonism. Magmatic rutile in the syenite forms millimetric-scale crystals rimmed by magmatic titanite and magnetite and also occurs as smaller interstitial crystals.

The syenite was synchronous with the later phases of regional A-type granite plutonism. Later hydrothermal halogen-rich fluids, derived from dissolution of halite, produced widespread metasomatic scapolite in the syenite. Such fluids resulted in local dissolution-reprecipitation of Ti and Zr and resetting of the U-Pb system in the altered rutile, at Variations in dissolution and transport of Zr and Ti by halogen-rich fluids affect the Zr in rutile geothermometer, which yields unrealistic temperatures when applied in this study.

Chemical Geology , , pp. View at publisher. LA-ICPMS dating of these U-bearing accessory phases typically requires a matrix-matched standard, and data reduction is often complicated by variable incorporation of common Pb not only into the unknowns but also particularly into the reference material. Common Pb correction of the age standard can be undertaken using either the Pb, Pb or Pb no Th methods, and the approach can be applied to raw data files from all widely used modern multi-collector and single-collector ICPMS instruments.

This downhole fractionation model is applied to the unknowns and sample-standard bracketing using a user-specified interpolation method is used to calculate final isotopic ratios and ages. Pb and Pb no Th corrected concordia diagrams and Pb, Pb and Pb no Th -corrected age channels can be calculated for user-specified initial Pb ratio s.

used to date events from the beginning of the solar system to U-Th-Pb geochronology is also used as the standard by which all Closure Temperatures of Common U-Pb Chronometers. Zircon. Baddeleyite. Monazite. Rutile. Titanite. Apatite.

Rutile is a common accessory mineral that occurs in a wide spectrum of metamorphic rocks, such as in blueschists, eclogites, and granulites and as one of the most stable detrital heavy minerals in sedimentary rocks. The advent of rutile trace element thermometry has generated increased interest in a better understanding of rutile formation. Rutile thermometry of the same detrital grains indicates former granulite-facies conditions. The methods outlined in this paper should find wide application in studies that require age information of single spots, e.

Rutile is a common accessory mineral that is found in a wide range of rock types on Earth and beyond e. On Earth, all major rock types exhibit rutile-bearing samples. However, rutile forms predominantly in metamorphic rocks. In general, rutile is more common in metapelitic than in metamorphic rocks see the Ivrea example; Zingg ; Luvizotto and Zack and is more common in higher-pressure samples compared to their lower-pressure counterparts see discussion in Zack et al.

Clastic sediments are important rutile-bearing rocks since rutile is one of the most stable minerals during weathering, transport, and diagenesis Hubert ; Force ; Morton and Hallsworth Despite its common occurrence, rutile has so far received less attention as a geochronometer than zircon and monazite.

534 #18 – Absolute radiometric age dating of rocks and geologic materials


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