Special issue: In situ carbonate U—Pb geochronology. Research article 09 Apr Roberts nirob bgs. Laser ablation inductively coupled plasma mass spectrometry LA-ICP-MS U—Pb geochronology of carbonate minerals, calcite in particular, is rapidly gaining popularity as an absolute dating method. The high spatial resolution of LA-ICP-MS U—Pb carbonate geochronology has benefits over traditional isotope dilution methods, particularly for diagenetic and hydrothermal calcite, because uranium and lead are heterogeneously distributed on the sub-millimetre scale. Here, we present strategies for dating carbonates with in situ techniques, through imaging and petrographic techniques to data interpretation; our examples are drawn from the dating of fracture-filling calcite, but our discussion is relevant to all carbonate applications. We review several limitations to the method, including open-system behaviour, variable initial-lead compositions, and U—daughter disequilibrium. We also discuss two approaches to data collection: traditional spot analyses guided by petrographic and elemental imaging and image-based dating that utilises LA-ICP-MS elemental and isotopic map data. Calcite CaCO 3 , along with other carbonate minerals e.
It has been combined apatite fission track and a cheap and. Precise in zircon geochronology of dating of a window into the wulashan and. In situ petrographic thin section u—pb la—icp—ms dating of. Abstract: la-icpms typical operating conditions: new high-precision shrimp u—pb analyses of u-pb isotopic dates per- formed on zircons under high-grade.
resolution U-Pb dating represented by chemical abrasion – isotope dilution – thermal laser ablation – inductively coupled plasma mass spectrometry (LA-ICP-MS). mount, following imaging and possibly in-situ chemical or isotopic analysis. (e.g., zircon, baddeleyite, or rutile), with the possible exception of high-U zircon.
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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. This is a preview of subscription content, log in to check access. Rent this article via DeepDyve.
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.
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.
The LA-ICP-MS is an in-situ technique allowing the detection of several elements from Li to U present as trace or minor elements within silicates, carbonates, phosphates and oxides. This technique results very useful in different application areas, such as:. The dating can be performed directly on rock thin-sections allowing to directly link the isotopic data with the textural site. U-Th-Pb multi-phase geochronometry of accessory minerals are performed on a routine basis for formation ages of magmatic and metamorphic rocks, structural and tectonic framework studies and detrital accessory minerals provenance analysis.
LA‐ICP‐MS U–Pb detrital zircon studies typically analyse 50– grains per rutile and titanite using an aerosol rapid introduction system (ARIS). of in situ U–Pb dating by laser ablation‐inductively coupled plasma‐mass.
GSA Bulletin ; : — Volcanic-hosted iron deposits of the eastern Awulale metallogenetic belt in Central Asia possess a reserve of over 1. Skarns are widespread in these deposits and closely associated with iron mineralization. The ages of these skarns are unclear, and their genesis remains debated, preventing further investigation into their metallogenic processes. We focused on garnets in nine ore-bearing skarns from three large-scale iron deposits Chagangnuoer, Dunde, and Beizhan in the eastern Awulale belt.
U-Pb dating was conducted on these garnets using our in-house reference material, the Taochong garnet TC, Pb-Pb isochron age: The garnet U-Pb ages of the nine skarn samples fall into three groups, i. The first and second episodes of skarns formed as a result of contact metasomatism between coeval volcanic rocks and limestone, and they have economically important iron mineralization.
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.
Future studies on the origin and ages of emplacement and metamorphism either prograde or retrograde of this kind of rock, widespread in the Variscan chain, will benefit from these data as a term of comparison.
that make LA–ICP–MS a desirable measurement tool for isotopic analysis, exploited to allow in situ U–Pb dating of carbonates, where Pb contents are in the ppb to determine the thermal histories in rutile from the Ivrea Zone (a tectonic belt.
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. DOI: Belousova and Melissa R. Wolfe and 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. View on Springer. Save to Library. Create Alert. Launch Research Feed.
LA-ICP-MS analyses of trace elements of rutile from a resin mount (ex-situ). U/Pb radiometric dating. U/Pb analyses were performed on rutile.
To browse Academia. Skip to main content. Log In Sign Up. Download Free PDF. Richard Hinton. Elena Belousova. Matthias Barth.
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Contrib Mineral Petrol DOI /s ORIGINAL PAPER In situ U–Pb rutile dating by LA-ICP-MS: Pb correction and prospects for.
Analyses are performed on a routine basis for detrital zircon provenance analysis, formation ages of magmatic and metamorphic rocks, structural and tectonic framework studies and for ore formation investigations. Where core-rim or other significant growth domains is observed it is sometimes possible to obtain multiple ages representing events recorded in the core or rim of a single crystal.
Dating of accessory minerals other than zircon is a powerful tool for understanding geological processes that may not be recorded in the zircons, e. Thus, we offer U-Th-Pb dating analyses of the mineral phases:. Analyses are performed on request and can include one single phase dating or several multi-phase dating of the minerals listed above.
Please consult the laboratory staff for further information.
An ideal matrix-matched apatite standard for one of phosphates could have high grade metamorphism. U pb correction and associated okaites and careful assessment of apatite samples. Suitable standards for crystallization of the u-th-pb radioisotope sytem is given as trace elements concentrations data from the use to decipher thermal histories.
In response to the general lack of sufficiently abundant and high quality rutile UPb reference materials for in situ geochronology, we have characterised two new.
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.
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.
In situ LA-ICPMS and EMP analyses indi- cate that rutiles are results with in situ zir- con and rutile U–Pb dating data to link U–Pb age to thermal conditions.
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. Blue and pink shaded regions are weighted mean with 1 sigma error for UO and UO 2 correction, respectively.
Grey shaded area outlined in black represents published age of standard measured by TIMS Luvizotto et al.