Sr-Nd isotope geochemistry of the early Precambrian sub-alkaline mafic igneous rocks from the southern Bastar craton, Central India

Sr–Nd isotope data are reported for the early Precambrian sub-alkaline mafic igneous rocks of the southern Bastar craton, central India. These mafic rocks are mostly dykes but there are a few volcanic exposures. Field relationships together with the petrological and geochemical characteristics of these mafic dykes divide them into two groups; Meso-Neoarchaean sub-alkaline mafic dykes (BD1) and Paleoproterozoic (1.88 Ga) sub-alkaline mafic dykes (BD2). The mafic volcanics are Neoarchaean in age and have very close geochemical relationships with the BD1 type. The two groups have distinctly different concentrations of high-field strength (HFSE) and rare earth elements (REE). The BD2 dykes have higher concentrations of HFSE and REE than the BD1 dykes and associated volcanics and both groups have very distinctive petrogenetic histories. These rocks display a limited range of initial 143Nd/144Nd but a wide range of apparent initial 87Sr/86Sr. Initial 143Nd/144Nd values in the BD1 dykes and associated volcanics vary between 0.509149 and 0.509466 and in the BD2 dykes the variation is between 0.510303 and 0.510511. All samples have positive εNd values the BD1 dykes and associated volcanics have εNd values between +0.3 and +6.5 and the BD2 dykes between +1.9 to +6.0. Trace element and Nd isotope data do not suggest severe crustal contamination during the emplacement of the studied rocks. The positive εNd values suggest their derivation from a depleted mantle source. Overlapping positive εNd values suggest that a similar mantle source tapped by variable melt fractions at different times was responsible for the genesis of BD1 (and associated volcanics) and BD2 mafic dykes. The Rb–Sr system is susceptible to alteration and resetting during post-magmatic alteration and metamorphism. Many of the samples studied have anomalous apparent initial 87Sr/86Sr suggesting post-magmatic changes of the Rb–Sr system which severely restricts the use of Rb–Sr for petrogenetic interpretation

Tall height and obesity are associated with an increased risk of aggressive prostate cancer: results from the EPIC cohort study

Background The relationships between body size and prostate cancer risk, and in particular risk by tumour characteristics, are not clear because most studies have not differentiated between tumours that are high grade and those that are advanced stage, but rather have assessed risk with a combined category of aggressive disease. We investigated the association of height and adiposity with incidence of and death from prostate cancer in 141,896 men in the European Prospective Investigation into Cancer and Nutrition (EPIC). Methods Multivariable-adjusted Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). After an average of 13.9 years of follow-up there were 7,024 incident prostate cancers and 934 prostate cancer deaths. Results Height was not associated with total prostate cancer risk. Subgroup analyses showed heterogeneity in the association with height by tumour grade (Pheterogeneity=0.002), with a positive association with risk for high grade, but not low-intermediate grade, disease (HR for high grade disease tallest versus shortest fifth of height 1.54, 95% CI 1.18-2.03). Greater height was also associated with a higher risk for prostate cancer death (HR=1.43, 1.14-1.80). BMI was significantly inversely associated with total prostate cancer, but there was evidence of heterogeneity by tumour grade (Pheterogeneity=0.01; HR=0.89, 0.79-0.99 for low-intermediate grade and HR=1.32, 1.01-1.72 for high grade prostate cancer) and stage (Pheterogeneity=0.01; HR=0.86, 0.75-0.99 for localized stage and HR=1.11, 0.92-1.33 for advanced stage). BMI was positively associated with prostate cancer death (HR=1.35, 1.09-1.68). The results for waist circumference were generally similar to those for BMI, but the associations were slightly stronger for high grade (HR=1.43, 1.07-1.92) and fatal prostate cancer (HR=1.55, 1.23-1.96). Conclusions The findings from this large prospective study show that men who are taller and who have greater adiposity have an elevated risk of high grade prostate cancer and prostate cancer death.</p