نتایج جستجو برای: mafic composition

تعداد نتایج: 261231  

2015
Cin-Ty A. Lee Don L. Anderson

The total magmatic output in modern arcs, where continental crust is now being formed, is believed to derive from melting of the mantle wedge and is largely basaltic. Globally averaged continental crust, however, has an andesitic bulk composition and is hence too silicic to have been derived directly from the mantle. It is well known that one way this imbalance can be reconciled is if the paren...

2017
M. G. A. Lapotre B. L. Ehlmann S. E. Minson R. E. Arvidson R. C. Ewing Mathieu Lapotre

During its ascent up Mount Sharp, the Mars Science Laboratory Curiosity rover traversed the Bagnold Dune Field. We model sand modal mineralogy and grain size at four locations near the rover traverse, using orbital shortwave infrared single scattering albedo spectra and a Markov-Chain Monte Carlo implementation of Hapke’s radiative transfer theory to fully constrain uncertainties and permitted ...

2004
Anne V. McGuire

Marie and intermediate granulite xenoliths, collected from Cenozoic alkali basalts, provide samples of the lower crust in western Saudi Arabia. The xenoliths are metaigneous two-pyroxene and garnet granulites. Mineral and whole rock compositions are inconsistent with origin from Red Sea rift-reIated basalts, and are compatible with origin from island arc calc-alkatine and low-potassium tholeiit...

2015
S. Wiesmaier D. Morgavi C. J. Renggli D. Perugini C. P. De Campos K.-U. Hess W. Ertel-Ingrisch Y. Lavallée D. B. Dingwell

In order to explore the materials’ complexity induced by bubbles rising through mixing magmas, bubbleadvection experiments have been performed, employing natural silicate melts at magmatic temperatures. A cylinder of basaltic glass was placed below a cylinder of rhyolitic glass. Upon melting, bubbles formed from interstitial air. During the course of the experimental runs, those bubbles rose vi...

2014
Hiroshi Nagaoka Hiroshi Takeda Yuzuru Karouji Makiko Ohtake Akira Yamaguchi Shigekazu Yoneda Nobuyuki Hasebe

Remote observation by the reflectance spectrometers onboard the Japanese lunar explorer Kaguya (SELENE) showed the purest anorthosite (PAN) spots (>98% plagioclase) at some large craters. Mineralogical and petrologic investigations on the feldspathic lunar meteorites, Dhofar 489 and Dhofar 911, revealed the presence of several pure anorthosite clasts. A comparison with Apollo nearside samples o...

Journal: :Journal of Petrology 2021

Abstract Granitoids are the main constituents of continental crust, and an understanding their petrogenesis is key to origin evolution continents. Whether crystal fractionation dominant way generate evolved magmas has long been debated, mostly because such processes would produce large volumes complementary cumulates, which remains elusive. Mafic magmatic enclaves (MMEs) ubiquitous in granitoid...

Journal: :Geochemistry Geophysics Geosystems 2021

Abstract We present major and trace element data on clinopyroxene‐hosted, glassy melt inclusions (MIs) from a highly enriched (high 87 Sr/ 86 Sr = 0.71856) lava (ALIA‐D115‐18) the Samoan hot spot. Following correction for post‐entrapment crystallization, MIs are trachytic (62.6–65.4 wt% SiO 2 , 1.5–3.0 MgO, 7.2–10.6 total alkalis (Na O + K O)) ALIA‐D115 lavas dredged off submarine flanks of Sav...

2018
J Gregory Shellnutt

Geochemical modeling using the basalt composition analyzed at the Vega 2 landing site indicates that intermediate to silicic liquids can be generated by fractional crystallization and equilibrium partial melting. Fractional crystallization modeling using variable pressures (0.01 GPa to 0.5 GPa) and relative oxidation states (FMQ 0 and FMQ -1) of either a wet (H2O = 0.5 wt%) or dry (H2O = 0 wt%)...

2016
Julie Reveillaud Emily Reddington Jill McDermott Christopher Algar Julie L. Meyer Sean Sylva Jeffrey Seewald Christopher R. German Julie A. Huber

Warm fluids emanating from hydrothermal vents can be used as windows into the rocky subseafloor habitat and its resident microbial community. Two new vent systems on the Mid-Cayman Rise each exhibits novel geologic settings and distinctively hydrogen-rich vent fluid compositions. We have determined and compared the chemistry, potential energy yielding reactions, abundance, community composition...

2012
J. Fullea A. G. Jones J. C. Afonso

[1] Recent advances in computational petrological modeling provide accurate methods for computing seismic velocities and density within the lithospheric and sub-lithospheric mantle, given the bulk composition, temperature, and pressure within them. Here, we test an integrated geophysical-petrological inversion of Rayleighand Love-wave phase-velocity curves for fine-scale lithospheric structure....

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