<sup>238</sup>
            U/
            <sup>235</sup>
            U Systematics in Terrestrial Uranium-Bearing Minerals

Hiess, Joe; Condon, Daniel J.; McLean, Noah; Noble, Stephen R.

doi:10.1126/science.1215507

Cited by 621 publications

(300 citation statements)

References 75 publications

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“…They found a significantly lower average ratio of 137.837. Hiess et al [324] confirmed the basic finding and published results for a large number of terrestrial minerals. They suggest that the U variations of the order of 1 ‰ have been observed in naturally occurring terrestrial materials [317].…”

Section: Uraniumsupporting

confidence: 80%

Assessment of international reference materials for isotope-ratio analysis (IUPAC Technical Report)

Brand

Coplen

Vogl

et al. 2014

Pure and Applied Chemistry

546

436

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Abstract:Since the early 1950s, the number of international measurement standards for anchoring stable isotope delta scales has mushroomed from 3 to more than 30, expanding to more than 25 chemical elements. With the development of new instrumentation, along with new and improved measurement procedures for studying naturally occurring isotopic abundance variations in natural and technical samples, the number of internationally distributed, secondary isotopic reference materials with a specified delta value has blossomed in the last six decades to more than 150 materials. More than half of these isotopic reference materials were produced for isotope-delta measurements of seven elements: H, Li, B, C, N, O, and S. The number of isotopic reference materials for other, heavier elements has grown considerably over the last decade. Nevertheless, even primary international measurement standards for isotope-delta measurements are still needed for some elements, including Mg, Fe, Te, Sb, Mo, and Ge. It is recommended that authors publish the delta values of internationally distributed, secondary isotopic reference materials that were used for anchoring their measurement results to the respective primary stable isotope scale.

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Section: Uraniumsupporting

confidence: 80%

Assessment of international reference materials for isotope-ratio analysis (IUPAC Technical Report)

Brand

Coplen

Vogl

et al. 2014

Pure and Applied Chemistry

546

436

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“…Analytical parameters and metadata are listed in supplementary information 1. (Hiess et al, 2012). The Pb/Pb and U/Pb ratios were normalised to bracketing primary reference material 91500, based on the average measured value of the reference material compared to the ratio determined by ID-TIMS (Wiedenbeck et al, 1995).…”

Section: Geochronological Methodsmentioning

confidence: 99%

Geochronology of the central Tanzania Craton and its southern and eastern orogenic margins

Thomas

Spencer

Bushi³

et al. 2016

Precambrian Research

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Geological mapping and zircon U-Pb/Hf isotope data from 35 samples from the central Tanzania Craton and surrounding orogenic belts to the south and east allow a revised model of Precambrian crustal evolution of this part of East Africa. The geochronology of two studied segments of the craton shows them to be essentially the same, suggesting that they form a contiguous crustal section dominated by granitoid plutons. The oldest orthogneisses are dated at ca. 2820 Ma (Dodoma Suite) and the youngest alkaline syenite plutons at ca. 2610 Ma (Singida Suite). Plutonism was interrupted by a period of deposition of volcano-sedimentary rocks metamorphosed to greenschist facies, directly dated by a pyroclastic metavolcanic rock which gave an age of ca. 2725 Ma. This is supported by detrital zircons from psammitic metasedimentary rocks, which indicate a maximum depositional age of ca. 2740 Ma, with additional detrital sources 2820 and 2940 Ma. Thus, 200 Ma of episodic magmatism in this part of the Tanzania Craton was punctuated by a period of uplift, exhumation, erosion and clastic sedimentation/volcanism, followed by burial and renewed granitic to syenitic magmatism.In eastern Tanzania (Handeni block), in the heart of the East African Orogen, all the dated orthogneisses and charnockites (apart from those of the overthrust Neoproterozoic granulite nappes), have Neoarchaean protolith ages within a narrow range between 2710 and 2630 Ma, identical to (but more restricted than) the ages of the Singida Suite. They show evidence of Ediacaran "Pan-African" isotopic disturbance, but this is poorly defined. In contrast, granulite samples from the Wami Complex nappe were dated at ca. 605 and ca. 675 Ma, coeval with previous dates of the "Eastern Granulites" of eastern Tanzania and granulite nappes of adjacent NE Mozambique. To the south of the Tanzania Craton, samples of orthogneiss from the northern part of the Lupa area were dated at ca. 2730 Ma and clearly belong to the Tanzania Craton. However, granitoid samples from the southern part of the Lupa "block" have Palaeoproterozoic (Ubendian) intrusive ages of ca. 1920 Ma. Outcrops further south, at the northern tip of Lake Malawi, mark the SE continuation of the Ubendian belt, albeit with slightly younger ages of igneous rocks (ca. 1870-1900 Ma) which provide a link with the Ponte Messuli Complex, along strike to the SE in northern Mozambique.In SW Tanzania, rocks from the Mgazini area gave Ubendian protolith ages of ca. 1980-1800 Ma, but these rocks underwent Late Mesoproterozoic high-grade metamorphism between 1015 and 1040 Ma. One granitoid gave a crystallisation age of ca. 1080 Ma correlating with known Mesoproterozoic crust to the east in SE Tanzania and NE Mozambique. However, while the crust in the Mgazini area was clearly one of original Ubendian age, reworked and intruded by granitoids at ca. 1 Ga, the crust of SE Tanzania is a mixed Mesoproterozoic terrane and a continuation from NE Mozambique. Hence the Mgazini area lies at the edge of the Ubendian belt which was re...

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“…DR3). This tuff yielded abundant euhedral zircons that we treated with the chemical abrasion method prior to acquiring U-Pb isotope dilution thermal ionization mass spectrometry data ( Figs U ratio of zircon (Hiess et al, 2012). For comparisons with previously published dates, our new date can be recalculated using the legacy Table DR3).…”

Section: New Age Constraint For the Mamainse Point Successionmentioning

confidence: 99%

Magmatic activity and plate motion during the latent stage of Midcontinent Rift development

Swanson‐Hysell

Burgess

Maloof

et al. 2014

Geology

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The Keweenawan Midcontinent Rift of North America records signifi cant continental rifting between ca. 1110 and 1085 Ma, and preserves the most detailed paleomagnetic record of plate motion of any continent in Precambrian time. U/Pb dates from extrusive and intrusive rocks of the western Lake Superior Basin suggest a latent stage of reduced magmatic activity from ca. 1106 to 1100 Ma that places constraints on the dynamics of rift development and the record of plate motion. However, it has remained unclear whether this stage is a feature of the entire >2500-km-long rift. The succession of picritic and basaltic lava fl ows at Mamainse Point in the eastern Lake Superior Basin may be the most continuous and best exposed record of rift-related volcanism and magnetic reversals, but its age and duration relative to the latent stage has been uncertain due to a lack of radioisotopic dates. We present a weighted mean 206 Pb/ 238 U date of 1100.36 ± 0.25 Ma on zircon crystals isolated from a newly discovered tuff within the upper reversed polarity portion of the stratigraphy below the Great Conglomerate. This date indicates that eruptive activity at Mamainse Point continued during the interval of diminished magmatic activity in the western Lake Superior Basin. This result strengthens the chronostratigraphic framework of rift development while explaining the preservation of additional geomagnetic reversals at Mamainse Point and the record of progressively decreasing paleomagnetic inclination that is indicative of rapid paleogeographic change.

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²³⁸ U/ ²³⁵ U Systematics in Terrestrial Uranium-Bearing Minerals

Cited by 621 publications

References 75 publications

Assessment of international reference materials for isotope-ratio analysis (IUPAC Technical Report)

Assessment of international reference materials for isotope-ratio analysis (IUPAC Technical Report)

Geochronology of the central Tanzania Craton and its southern and eastern orogenic margins

Magmatic activity and plate motion during the latent stage of Midcontinent Rift development

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238 U/ 235 U Systematics in Terrestrial Uranium-Bearing Minerals

Cited by 621 publications

References 75 publications

Assessment of international reference materials for isotope-ratio analysis (IUPAC Technical Report)

Assessment of international reference materials for isotope-ratio analysis (IUPAC Technical Report)

Geochronology of the central Tanzania Craton and its southern and eastern orogenic margins

Magmatic activity and plate motion during the latent stage of Midcontinent Rift development

Contact Info

Product

Resources

About

²³⁸ U/ ²³⁵ U Systematics in Terrestrial Uranium-Bearing Minerals