...Yi Sun; Axel K. Schmitt; Lucia Pappalardo; Massimo Russo Abstract Initial excess protactinium ( 231 Pa) is a frequently suspected source of discordance in baddeleyite (ZrO 2 ) geochronology, which limits accurate U/Pb dating, but such excesses have never been directly demonstrated. In this study...

... that is close to the (known) rate of production of 230 Th by U decay in the overlying water column. Protactinium-231 is another U-series nuclide, and the 231 Pa/ 230 Th ratio reflects changes in particle flux, primarily opal flux (e.g. Anderson et al. 2009 ) ( F ig . 3B ) as well as changes in circulation...

.... , Cheng , H. , and Edwards , R.L. , 2005 , Time scale of magma differentiation in arcs from protactinium-radium isotopic data : Geology , v. 33 pp. 633 - 636 doi: 10.1130/G21638.1. Beattie , P. , 1993 , Uranium-thorium disequilibria and partitioning on melting of garnet...

.... PROTACTINIUM, RADIUM, THORIUM, AND URANIUM DATA Figure 1. A: Variation of ( 231 Pa/ 235 U) vs. MgO of Taal lavas, ranging in composition from tholeiitic basalt (highest MgO) to evolved rhyodacite (lowest MgO). Samples fall on model isochron of magma differentiation. Age model relates degree...

.... A second effect, and apparently more unusual in occurrence, has been inferred in two samples of igneous zircon. Protactinium-231 is the most long-lived intermediate isotope in the 235 U decay series, with a half-life of approximately 32,500 years and there are no other stable or long-lived isotopes of Pa...

... of the aragonite: 231 Pa measurements and their relationship to carbonate dating follow a similar history. Protactinium was discovered by Fajans and Gohring in 1913 in studies of 234 Pa. Protactinium was initially called “brevium” reflecting 234 Pa’s short half-life (6.7 hours). Meitner and Hahn identified...

.... Protactinium and Th associated with airborne particulates can be incorporated into secondary deposits. Also, intermittent flooding events can transport a supply of detrital material. U and Th concentrations in secondary deposits precipitated from solution generally reflect relative abundances...

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