نتایج جستجو برای: lead isotopes
تعداد نتایج: 362795 فیلتر نتایج به سال:
Large stratiform, syngenetic deposits commonly yield galena-lead isotope 'model' ages that agree closely with the stratigraphic ages of their host rocks. However, analyses in Table 1 from stratiform,shale-hosted deposits (located on Fig. 701 of Cambrian to Devono-Mississippian age in or adjacent to the Selwyn Bar,in in British Columbia and Yukon Territory do not give reasonable ages if the mode...
We report the first measurements of Pb isotopes in Antarctic snow, which show that even recent snow containing 2.3 pg/g is highly polluted with anthropogenic Pb. This follows from a comparison of isotope abundances of Pb in surface snow and terrestrial dust extracted from ancient Antarctic ice (Dome C, depth 308 m, approximate age 7,500 a BP), the latter being distinctly more radiogenic. This r...
the nasirabad manganese deposit is located 5 km south of nasirabad, 8 km sw of neyriz in the fars province. structurally, the area is placed in the southeastern part of zagros thrust belt. in this area, the manganese mineralization occurred as ore layers and nodules, interlayered with pichakun radiolarite chert deposits. in this study, mineralogy and geochemistry of uranium, thorium and lead is...
the cu, pb, zn, ag-au deposit of amensif is located on the northern flank of the western high atlas. this deposit is hosted in lower cambrian carbonate bars and is structurally controlled by ne-sw to e-w trending fault structures and is spatially associated with the permian 273 ma azegour granite. ore reserves are around 0.5 mt and grades are 3.21% zn, 0.58% pb, 0.86% cu with 83.31 ppm ag and 0...
Anthropogenic emissions completely overwhelmed natural marine lead (Pb) sources during the past century, predominantly due to leaded petrol usage. Here, based on Pb isotope measurements, we reassess the importance of natural and anthropogenic Pb sources to the tropical North Atlantic following the nearly complete global cessation of leaded petrol use. Significant proportions of up to 30-50% of ...
Samples of Fish Canyon and Cobb Mountain sanidine monitor standards, irradiated and fused with 7 W of CO laser 2 power for ArrAr geochronology analyses, give Pb isotope composition and Pb concentrations that are indistinguishable from unprocessed aliquots of the same monitors. The absence of measurable change in Pb isotope composition indicates the feasibility of measuring the Pb isotope compos...
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