However, uncertainties in mantle rheology, temperature, and initial conditions make such models nonunique. Predictions of plume drift arising from mantle convection models and broadly satisfying observed paleolatitudes have so far provided the only framework for deriving absolute plate motions over moving hotspots. Paleomagnetic evidence for plume drift has made modeling of absolute plate motions challenging, especially since direct observations of plume drift are lacking. Modeling absolute plate and plume motionsīodinier, G. The whole-rock analysis of each individual sample yields consistently higher initial 187Os/188Os isotope ratios than the corresponding organic matter analysis and suggests that a significant radiogenic detrital Os component is present The well-defined Re-Os systematics of the OFP slates demonstrates for the first time that the Re-Os system is not disturbed in organic-rich sediments during lower greenschist (-chlorite) grade metamorphic conditions. These absolute age results are in accord with existing age constraints (e.g., stratigraphically younger Hamill Group with a U-Pb zircon age of 569 Ma). Using a method designed to selectively dissolve organic matter alone, an age of 609.0 +/- 8.3 Ma (MSWD = 1.5 initial 187Os/188Os = 0.62 +/- 0.05) is obtained. An age of 620.8 +/- 8.1 Ma (MSWD = 0.9 initial 187Os/188Os = 0.68 +/- 0.06) is obtained using conventional aqua regia dissolution. Despite the relatively low Re (6-16 ppb) and Os (0.07-0.14 ppb) concentrations and total organic contents (~ 0.5% TOC) of the slates compared to other organic-rich mudrocks used in previous Re-Os isotope studies, precise well-fitted Re-Os isochrons have been obtained with two different dissolution methods. The OFP has been interpreted as the deep water expression of post-glacial sea level rise and therefore is comparable stratigraphically to cap carbonates that immediately overlie glaciogenic deposits worldwide. In this study, the Re-Os isotope systematics of dark gray, sulfidic slates from the Old Fort Point Formation (OFP) of the Windermere Supergroup (near Jasper, Alberta) were examined to test the ability of the Re-Os geochronometer to provide an absolute age constraint for a Neoproterozoic glaciogenic deposit. M.Ībsolute-age constraints on the Neoproterozoic glaciations are generally poor due to a paucity of suitable plutonic and volcanic igneous rocks that are temporally and spatially related to Neoproterozoic glaciogenic deposits and are amenable to radiometric dating methods. Researchers should critically consider the implications of choosing a specific age group, in addition to the indicator ofĮvaluation of the Re-Os Geochronometer in Organic-rich Mudrocks as a Method for Constraining the Absolute Ages of Neoproterozoic Glaciogenic Deposits Conclusions Absolute and relative socioeconomic health inequalities differed cross-sectionally across age groups by indicator of socioeconomic position, health outcome and gender. Gini-coefficients were largest in young age groups and smallest in older age groups. Relative inequalities were most pronounced for physical health by educational level. They were larger in younger than older age groups. Absolute inequalities were most pronounced for mental health by household income. Results Absolute and relative socioeconomic health inequalities differed across age groups by indicator of socioeconomic position, health outcome, and gender. Analyses were performed for all age groups, and stratified by gender. Analyses were performed for both health outcomes by both educational level and household income. Relative inequalities were examined by comparing Gini-coefficients. Absolute inequalities were examined by comparing means. Physical and mental health were measured with the RAND-36. Socioeconomic position was measured as educational level and household income. Methods The study sample was derived from the baseline measurement of the LifeLines Cohort Study and consisted of 95,432 participants. The aim is to investigate whether absolute and relative socioeconomic health inequalities differ across age groups by indicator of socioeconomic position, health outcome and gender. It is less clear whether socioeconomic health inequalities differ across age groups by other factors that are known to affect the relation between socioeconomic position and health, like the indicator of socioeconomic position, the health outcome, gender, and as to whether socioeconomic health inequalities are measured in absolute or in relative terms. Reijneveld, Sijmen A.īackground The magnitude of socioeconomic health inequalities differs across age groups. Absolute and Relative Socioeconomic Health Inequalities across Age Groups
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