Rutile u pb dating
Crystals larger than 0.5 mm yielded sufficiently precise Pb ratios to correct for the presence of common Pb, and individual rutile crystals often exhibited sufficient Pb isotopic heterogeneity to allow isochron calculations to be performed on replicate analyses of a single crystal.
The mean of 12 isochron ages is 1544 ± 8 Ma (2 SD), with isochron ages for single crystals having uncertainties as low as ±1.3 Myr (2 SD).
A new rutile standard for in situ U-Pb dating, Wodgina, has been characterised by SHRIMP, TIMS and limited LA-ICPMS analysis.
Wodgina allows SHRIMP Pb-U calibration with a precision of 3.5-5.5% (2σ).
DOI: 10.31897/PMI.2018.4.357 Introduction and problem statement. The widely known Pizhemskoe titanium deposit and the Ichetju polymineral occurence, located in the Middle Timan (Komi Republic), promise to be in a great demand both in terms of giant titanium and quartz sandstones of glass quality resources and the possible expansion of the list of promising mineral components (rare metals - yttrium, zirconium, niobium, rare earth elements, diamonds, etc.).
The main minerals among the 50 indicated are quartz, rutile, anatase, niobium rutile, ilmenite, zircon, mona-zite, columbite, garnets, chromespinelide, tourmaline, staurolite, gold with silver impurities, rounded diamonds of the Urals-Brazilian type .
The of monazite ⩽0.1 mm in diameter, but significantly higher than the Rb-Sr system in muscovite (550 °C), phlogopite (435 °C) and biotite (400 °C). 600-640 °C for rutile 0.1-0.2 mm diameter cooled at 3 °C/Myr; near 600 °C [Cherniak D.
Obviously, a placer hypothesis of formation of titanium deposits of the Middle Timan which is supported by a number of researchers does not explain such temperature of rutile alteration. According to Rb-Sr isotopic data, the age of the titaniferous strata was determined as late Riphean - 685 ± 30 Ma . The quartz content in Pizhma leucoxene varies from 15 to 30 %. The schematic reaction of ilmenite transformation into leucoxene, which comes under a high temperature (510 ± 35) °C (the titanium-zircon geothermometer data ), can be represented as follows: 3Fe Ti O3 2Si O2 O2 CO2 ^ leucoxene 2[Ti O2]x[Si O2] Fe COs Fe2O3 Ti O2. Zircon dissolution controls the Hf isotope composition of subsequently-formed phases, which has implications for the interpretation of Hf isotope signatures in both metamorphic and magmatic settings.U-Pb ages of zircon from the IVZ record Permian growth and resetting events related to high temperature metamorphism and fluid influx, while U-Pb ages of rutile record cooling in the Jurassic and constrain the thermal evolution of the lower crustal section during rifting and exhumation.