نتایج جستجو برای: metamorphism and igneous
تعداد نتایج: 16828157 فیلتر نتایج به سال:
Microdiamonds from the Akluilâk minette dykes (Nunavut, Canada) are similar to diamonds formed in subducted metamorphic rocks. High concentrations of unaggregated nitrogen and positive delta(15)N suggest that the microdiamonds formed within rocks subducted to ultrahigh pressures before being sampled by the minette magma 1.8 billion years ago. This ultrahigh pressure metamorphism in North Americ...
Abstract Systematic changes in whole-rock chemistry, mineralogy, mineral textures, and chemistry are seen along a ca. 95-km traverse of late Archean granitoid orthogneisses the Shevaroy Block, Eastern Dharwar Craton, southern India. The passes from amphibolite-grade gneisses north to granulite-grade rocks (charnockite) south. Changes include depletion Rb, Cs, Th, U granulite grade as relative a...
Volatile emissions to the atmosphere associated with Siberian Traps eruptions at Permian-Triassic boundary were sourced from outgassing of primary magmas and sedimentary host rocks into which they intruded. Halogens in volcanic gases may have played an important role environmental degradation stratospheric ozone destruction. Here we investigate how halogens behave during interaction between sal...
The Shatak Formation, comprising a part of the Mashak Suite (RF2), is located on western slope Southern Urals. It consists various rock types, including sedimentary rocks, such as conglomerates, polymictic sandstones, aleurolites, and carbonaceous clayey shales, well igneous picrites, basalts, dacites, rhyodacites, rhyolites, volcanogenic–sedimentary tuffs tuff breccias. In this article, oxyflu...
The occurrence of plate tectonic processes on Earth during the Paleoproterozoic is supported by ca. 2.2–1.8 Ga subduction-collision orogens associated with assembly Columbia-Nuna supercontinent. Subsequent supercontinent breakup evidence global 1.8–1.6 large igneous provinces. North China craton notable for containing along its margins, herein named Northern Margin orogen, yet nature and timing...
Extensive work has been carried out by the U.S. Department of Energy (DOE) in the development of a proposed geologic repository at Yucca Mountain (YM), Nevada, for the disposal of high-level radioactive waste. In support of this development and an associated license application to the U.S. Nuclear Regulatory Commission (NRC), the DOE completed an extensive performance assessment (PA) for the pr...
[1] We present a new quantitative framework to understand the process of mantle melting based on the velocity structure of igneous crust. Our approach focuses on the lower crustal section, which is expected to be least affected by porosity and seawater alteration, especially for thick igneous crust. Our methodology is thus best for constraining the origin of large igneous provinces. First, a qu...
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