منابع مشابه
Multi-step TIMS and CA-TIMS monazite U–Pb geochronology
Multi-step chemical abrasion thermal ionization mass spectrometry (CA-TIMS) methods were developed for monazite using six samples that vary in composition and age—Amelia, Jefferson County, Burke, Elk Mountain, 554 and Madagascar. To evaluate whether the multi-step CA-TIMS approach reveals complexities in either age or composition that might be masked by single-step analysis, this study presents...
متن کاملA brief introduction into the Greenland U-Pb Geochronology Database
Geochronology aims to establish the age of rocks, minerals, and geological events including fluid movement and mineralization, within a specific degree of uncertainty, using signatures inherent in the rocks themselves. Absolute dating is only accomplished through the use of naturally-occurring radioactive isotopes found within geological samples. The U–Th–Pb isotopic system is the benchmark for...
متن کاملAlgorithms and software for U-Pb geochronology by LA-ICPMS
The past 15 years have produced numerous innovations in geochronology, including experimental methods, instrumentation, and software that are revolutionizing the acquisition and application of geochronological data. For example, exciting advances are being driven by Laser-Ablation ICP Mass Spectrometry (LA-ICPMS), which allows for rapid determination of U-Th-Pb ages with 10s of micrometer-scale...
متن کاملPII S 0016 - 7037 ( 00 ) 00408 - 7 206 Pb – 230 Th – 234 U – 238 U and 207 Pb – 235 U geochronology of Quaternary opal , Yucca Mountain , Nevada
U–Th–Pb isotopic systems have been studied in submillimeter-thick outermost layers of Quaternary opal occurring in calcite–silica fracture and cavity coatings within Tertiary tuffs at Yucca Mountain, Nevada, USA. These coatings preserve a record of paleohydrologic conditions at this site, which is being evaluated as a potential high-level nuclear waste repository. The opal precipitated from gro...
متن کاملOligocene partial melting in the Takab metamorphic complex, NW Iran: Evidence from in situ U-Pb geochronology
U-Pb ages obtained on zircons from the investigated migmatites place new constraints on the evolution of the crustal rocks in the Takab area. SHRIMP U-Pb dating of inherited zircon in the melanosome parts of mafic migmatites from the Takab complex gives a discordant age with an upper intercept of 2961±72 Ma (MSWD=0.5) and a lower intercept of 24.2±5.7 Ma (MSWD=1.7). In the concordia diagram, th...
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ژورنال
عنوان ژورنال: GEOCHEMICAL JOURNAL
سال: 1979
ISSN: 0016-7002
DOI: 10.2343/geochemj.13.167