Much of the Mid-European basement has been consolidated during the Variscan Orogeny and includes large volumes of granitic intrusions. Gamma radiation spectroscopic measurements in three study areas along the western margin of the Bohemian Massif give a record of radiogenic element concentrations in the Variscan granites. Most intrusions of the Fichtelgebirge (except for the Tin Granite) and intrusive complexes in the Bavarian Forest show Th/U ratios exceeding unity, most likely related to abundance of monazite. In contrast, some of the Oberpfalz granites located near the Saxothuringian-Moldanubian boundary (Flossenbürg, Steinwald and Friedenfels types) are characterized by higher uranium concentrations and thus Th/U < 1. The low Th/U ratios here are in agreement with a possible U mobilisation along the Saxothuringian-Moldanubian contact zone observed in previous studies. Heat production rates of granites in the three study areas vary between 3.9 and 8.9 µW/m 3 , with a mean of 4.9 µW/m 3. This classifies the intrusions as moderate-to high-heat-producing granites. Considering the huge volume of granitic bodies in the Variscan crust of the Bohemian Massif, the contribution of in situ radiogenic heat production had to have a major impact and should be considered in further thermal modeling.
In NW India, large volumes of exposed Neoproterozoic basement rocks are formed by two magmatic suites, Erinpura granites as a late thermal event with respect to the ∼1 Ga Delhi Orogeny and the younger Malani igneous suite (770-750 Ma). Average uranium and thorium equivalent concentrations (in ppm) inferred from spectroscopic gamma radiation survey are higher in Malani rocks (Th 47.33 ppm and U 6.95 ppm) as compared to the Erinpura granites (Th 33.55 ppm and U 4.77 ppm). These values are considerably above the granite world average (Th 14.8 ± 13.2 ppm; U 3.93 ± 3.27 ppm). High U (up to 19 ppm) and Th (up to 88 ppm) in some Malani granites and a constant Th-U ratio of 7 points to a high degree of fractionation of the felsic magma. Higher radioelement concentration in the east (Mirpur granite) as compared to the west (Jaswantpura granite) is substantiated by geochemical data. Areas to the west and east of the Sirohi frontal thrust show differences, most likely a consequence of anatexis in the eastern sector. A high linear correlation between inductively coupled plasma mass spectrometry and gamma-ray data underlines the suitability of in-situ measurements for the determination of U and Th concentrations during a field survey providing basic information for future petrogenetic and risk-hazard studies in this granitic terrain.
The Permo-Triassic Mass Extinction (PTME) was the most catastrophic biocrisis of the entire Phanerozoic. About 90% of all marine species became extinct near the P-Tr boundary, including all tabulate and rugose corals, trilobites and several brachiopod types, and many other groups including conodonts and ammonoids were severely affected (e.g., Bond & Grasby, 2017; Bond & Wignall, 2014; Erwin, 1994). The main phase of extinction occurred over a short time interval in the latest Permian (e.g., Bond & Grasby, 2017), this Late Permian Extinction (LPE) phase is recorded immediately below bed 25 in the Meishan stratotype section, with a second phase recorded in the basal Triassic at the bed 28/29 boundary at this location (Song et al., 2013). The absolute ages of these horizons are constrained by U-Pb zircon ages of 251.941 ± 0.037 and 251.880 ± 0.031 Ma for beds 25 and 28 respectively (Burgess et al., 2014), a period of 61 ± 48 kyr. These ages overlap with the ages of flood basalt volcanism in Siberia (251 Ma), at which time >2 × 10 6 km 3 of lava were erupted within a few 100 kyr (
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