Figure 16 - uploaded by Joaquín Alberto Cortés
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Feeder dike system in northern foothills of the Reveille Range. (A) Detailed map of dike set (red) illustrating en echelon character. Dike widths are typically several decimeters but are ~2 m at the widest locations. The dike system is hosted by volcaniclastic deposits. (B) Photo graph showing parts of three en echelon segments (see field of view in A). Bushes in foreground are ~30 cm in diameter.
Source publication
The Lunar Crater volcanic field (LCVF) in central Nevada (USA) is dominated by monogenetic mafic volcanoes spanning the late Miocene to Pleistocene. There are as many as 161 volcanoes (there is some uncertainty due to erosion and burial of older centers); the volumes of individual eruptions were typically ~0.1 km 3 and smaller. The volcanic field...
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The Campo de Calatrava is a natural region located in Ciudad Real province (Spanish Southern Plateau) where volcanic eruptions have occurred throughout the Mio–Pliocene and Quaternary, in a temporality between 8,6 ma. and 5200 BP. Rashes are organized in several stages and are therefore strombolian as effusive, but the interference of magma with wa...
Lakes, shallow lakes and volcanic wetlands are one of the most spectacular geological elements of the planet (Christenson et al, 2015), being the result of the interaction between magma and water outside the volcanic system (hydromagmatism), generally associated with groundwater (phreatomagmatism). Water-magma interaction generates an explosion fun...
Large-scale magmatic events like the emplacement of the North Atlantic Igneous Province (NAIP) are often coincident with periods of extreme climate change such as the Palaeocene–Eocene Thermal Maximum (PETM). One proxy for volcanism in the geological record that is receiving increased attention is the use of mercury (Hg) anomalies. Volcanic eruptio...
Large-scale magmatic events like the emplacement of the North Atlantic
Igneous Province (NAIP) are often coincident with periods of extreme climate
change such as the Palaeocene–Eocene Thermal Maximum (PETM). One proxy for
volcanism in the geological record that is receiving increased attention is
the use of mercury (Hg) anomalies. Volcanic eruptio...
Citations
Cenozoic basalts with low ε Nd (T) values (≤ +3) were recognized in southwest North America (SWNA) over 30 years ago and triggered an ongoing debate on whether this characteristic requires involvement of ancient continental lithospheric mantle (CLM) in basalt genesis. The abundant geochemical data now available from the SWNA basalts and entrained mantle xenoliths support such involvement and add insights into the Cenozoic tectonic evolution of the CLM of this region. For example, low εNd (T) and ε Hf (T) ultramafic xenoliths have been identified and confirm that LREE‐enriched, Precambrian CLM with isotopic compositions that overlap those of Cenozoic basalts existed beneath SWNA. High precision trace element data further demonstrate that low εNd (T) basalts can be subdivided into two groups based on whole rock Ta/Th values. Low Ta/Th (< 0.2) basalts are arc‐related melts generated in the asthenospheric mantle wedge that interacted with preexisting CLM during ascent. Intermediate Ta/Th (0.2 to 0.6) basalts are likely melts of CLM metasomatized by aqueous fluids derived from shallowly subducting oceanic lithosphere during the Laramide Orogeny. In situ melting of the metasomatized CLM after removal of subducted oceanic lithosphere produced the intermediate Ta/Th group rocks and potentially triggered weakening and return of CLM to the convecting mantle. Thinning of CLM allowed upwelling and decompression melting of asthenosphere and the eruption of high εNd (T) (> +3), high Ta/Th (> 0.6) basalts across the Basin and Range Province beginning at ~20 Ma and continuing to the present day.
