نتایج جستجو برای: magmatic association
تعداد نتایج: 509311 فیلتر نتایج به سال:
Introduction: Lunar pyroclastic deposits can be subdivided into several modes of occurrence [1], suggesting different modes of emplacement. For example, some smaller pyroclastic deposits have been interpreted to have erupted during strombolian/hawaiian activity [2], while others are linked to vulcanian activity related to dike and sill emplacement below crater floors [3,4]. The largest pyroclas...
School of Earth and Ocean Sciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3YE, UK The largest and most significant type of geological deposit of platinum group elements (PGEs) is that associated with magmatic base metal sulfide minerals in layered mafic or ultramafic igneous intrusions.The common association of PGEs with sulfide minerals is a result of processes of magmati...
Plate motion and associated tectonics explain the location of magmatic systems along plate boundaries [1], however, they cannot give satisfactory explanations of the origin of intra‐ plate volcanism. Intraplate magmatism such as that which created the Hawaiian Islands (Figure 1, hereafter for the location of geographical places the reader is referred to Figure 1) far from plate boundaries is co...
Fumarolic condensates and acid spring waters from Satsuma-Iwojima were sampled between 1993 and 1998 and analyzed for 129I/I and 36Cl/Cl ratios and chloride, bromine, and iodine concentrations. Halogen concentrations suggest that the fumarolic condensates represent mostly magmatic fluids, but that the hot springs are a mixture between magmatic fluids and meteoric water with some presence of sea...
Quartz is a common phase in high-silica igneous rocks and is resistant to post-eruptive alteration, thus offering a reliable record of magmatic processes in silicic magma systems. Here we employ the 75 ka Toba super-eruption as a case study to show that quartz can resolve late-stage temporal changes in magmatic δ18O values. Overall, Toba quartz crystals exhibit comparatively high δ18O values, u...
the borujerd complex of western iran is composed of intrusions and their surrounding contact aureole, with, pegmatites and quartz veins. pegmatites differ in mineralogy, origin and age, and two groups can be distinguished. the older pegmatites (about 120 ma age) intruded contact metamorphic rocks from the early magmatic stage, while the younger pegmatites (52-70 ma age) formed during the late m...
The source and nature of carbon on Mars have been a subject of intense speculation. We report the results of confocal Raman imaging spectroscopy on 11 martian meteorites, spanning about 4.2 billion years of martian history. Ten of the meteorites contain abiotic macromolecular carbon (MMC) phases detected in association with small oxide grains included within high-temperature minerals. Polycycli...
Schaller et al. (Research Article, 18 March 2011, p. 1404) proposed that carbon dioxide (CO(2)) released by the Central Atlantic Magmatic Province eruptions over periods of about 20,000 years led to substantial increases of up to 2000 parts per million (ppm) in the concentration of atmospheric carbon dioxide (PCO(2)) near the Triassic-Jurassic boundary. Use of an atmosphere-ocean model coupled ...
Regional distance seismic moment tensor determinations and broadband waveforms of moment magnitude 4.6 to 4.9 earthquakes from a November 1997 Long Valley Caldera swarm, during an inflation episode, display evidence of anomalous seismic radiation characterized by non-double couple (NDC) moment tensors with significant volumetric components. Observed coseismic dilation suggests that hydrothermal...
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