نتایج جستجو برای: zircon morphology
تعداد نتایج: 149157 فیلتر نتایج به سال:
Tracking hydrothermal events using zircon REE geochemistry from the Carajás Mineral Province, Brazil
Zircon geochemistry and geochronology are powerful tools in the study of multistage cratonic settings, yielding information on ages distinguishing terranes. The Carajás Mineral Province (CMP) SE Amazonian Craton is renowned for its complex tectonic evolution notable mineral deposits endowment, such as giant iron-oxide-copper-gold (IOCG)-type Sossego Salobo. Tectonic, magmatic, metamorphic, hydr...
We present geochronological evidence in the eastern Himalayan syntaxis (Namche Barwa) for high-pressure (HP) granulite-facies metamorphism and explain its importance for understanding both the deep continental subduction of the Indian plate beneath Asia and its subsequent exhumation. The timing of peak and retrograde metamorphism in part constrains these processes but is debated. We present zir...
Further lines of the anomalous optical absorption spectrum in low metamict zircon have been observed in the infra-red. Low-temperature polarization studies have enabled a clear distinction to be made between lines due to the anomalous spectrum and those due to the normal spectrum of U ~in zircon. Magnetic circular dichroism measurements showed, for the anomalous spectrum, only contributions due...
Craton cores far from plate boundaries have traditionally been viewed as stable features that experience minimal vertical motion over 100–1000 Ma time scales. Here we show that the Fennoscandian Shield in southeastern Sweden experienced several episodes of burial and exhumation from ~1800 Ma to the present. Apatite, titanite, and zircon (U-Th)/He ages from surface samples and drill cores constr...
The intense heat and pressure resulting from the detonation of the world’s first nuclear device in the New Mexico desert, July 16, 1945, severely altered the arkosic sand, producing the fused, glassy material referred to as Trinitite. The study of Trinitite is key to the development of nuclear forensic techniques that can provide crucial information about a nuclear event, such as device composi...
Recrystallization and structural recovery in α-decay damage in zircon samples have been studied using Raman spectroscopy. Fifteen zircon samples with different degrees of radiation damage have been thermally annealed between 600 K and 1800 K for up to 28 days and 8 hours. The experimental results from this study reveal that recrystallization in the damaged zircon samples is a multi-stage proces...
Accurate and precise dating of individual volcanogenic beds that spread across multiple sedimentary successions is a powerful tool to untangle stratigraphic age contradictions, since these horizons are deposited synchronously. In this study, we show that combining apatite chemistry with zircon age, Th/U ratio, and Hf isotope composition leads to reliable lateral correlation of volcanic horizons...
The high-pressure (HP) behaviour of scandium vanadate (ScVO4) is investigated under non-hydrostatic compression. The compound is studied by means of synchrotron-based powder x-ray diffraction (XRD) and optical-absorption techniques. The occurrence of a non-reversible phase transition is detected. The transition is from the zircon structure to the fergusonite-type structure and takes place aroun...
The scheelite form of the TbCrO4 oxide has been obtained by treating TbCrO4-zircon at 4 GPa and 823 K. X-ray and neutron diffraction data reveal that the high-pressure polymorph of TbCrO4 crystallizes with tetragonal symmetry space group I41 /a and lattice parameters a=5.036 74 10 Å and c=11.3734 4 Å. Although bisdisphenoids TbO8 and tetrahedra CrO4 are present in both scheelite and zircon poly...
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