نتایج جستجو برای: mafic magma

تعداد نتایج: 8846  

2016
Sofia De Gregorio Marco Camarda

In open conduit volcanoes, volatile-rich magma continuously enters into the feeding system nevertheless the eruptive activity occurs intermittently. From a practical perspective, the continuous steady input of magma in the feeding system is not able to produce eruptive events alone, but rather surplus of magma inputs are required to trigger the eruptive activity. The greater the amount of surpl...

2000
Mei-Fu Zhou Tai-Ping Zhao John Malpas Min Sun

Abundant mafic and ultramafic rocks including basalts, komatiitic basalts, and peridotites occur in the Proterozoic Sibao Group, northern Guangxi Province, China. Whereas the basalts are generally pillow lavas, the komatiitic basalts are typically spinifex-textured and, in a few cases, show pyroxene accumulation associated with Ni Cu (PGE) sulfide deposits. The peridotites occur in the lower po...

2009
J. F. Mustard B. L. Ehlmann S. L. Murchie F. Poulet N. Mangold J. W. Head J.-P. Bibring L. H. Roach

[1] Definitive exposures of pristine, ancient crust on Mars are rare, and the finding that much of the ancient Noachian terrain on Mars exhibits evidence of phyllosilicate alteration adds further complexity. We have analyzed high-resolution data from the Mars Reconnaissance Orbiter in the well-exposed Noachian crust surrounding the Isidis basin.We focus on data from the Compact Reconnaissance I...

2013
Mark Jellinek Donald J. DePaolo

The relatively low rates of magma production in island arcs and continental extensional settings require that the volume of silicic magma involved in large catastrophic caldera-forming (CCF) eruptions must accumulate over periods of 105 to 106 years. We address the question of why buoyant and otherwise eruptible highsilica magma should accumulate for long times in shallow chambers rather than e...

Journal: :Tectonophysics 2021

Abstract The crust of southern Tibet shows strong azimuthal and radial seismic anisotropies. However, their origin has remained ambiguous. Here we characterized the composition, microstructure, properties amphibole-rich deep-crust xenoliths exhumed rocks from a terrane in Tibet. show typical magmatic textures have amphiboles with homogenous chemical low intracrystalline deformation, but crystal...

2012
Shoshana Z. Weider Larry R. Nittler Richard D. Starr Timothy J. McCoy Karen R. Stockstill-Cahill Paul K. Byrne Brett W. Denevi James W. Head Sean C. Solomon

[1] We present the analysis of 205 spatially resolved measurements of the surface composition of Mercury from MESSENGER’s X-Ray Spectrometer. The surface footprints of these measurements are categorized according to geological terrain. Northern smooth plains deposits and the plains interior to the Caloris basin differ compositionally from older terrain on Mercury. The older terrain generally ha...

2009
James D. Miller

The Sonju Lake intrusion (SLI) is a 1200-m-thick, shallow-dipping, sheet-like intrusion that forms part of the Beaver Bay Complex (RI-58, Chapter 7). Although its exposed strike-length is only about 3 km (Fig. 3-1), the SLI has a distinctive aeromagnetic signature that can be traced for at least 20 km beneath a cover of glacial drift. The nearly constant width of its aeromagnetic anomaly sugges...

2013
H. Clenet M. Jutzi J.-A. Barrat Ph. Gillet

Introduction: Despite many studies on the Howardite-Eucrite-Diogenite (HED) meteorite suite, the internal structure of asteroid 4-Vesta is still debated. Some studies favor the hypothesis of a global magma ocean, leading to a layered structure and a relatively thin crust [e.g. 1]. Other petrological and geochemical evidences tend to favor a more complex structure, involving intrusions, which al...

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