Results 131 to 140 of about 9,921 (184)

Orogenic Massifs: Protolith, Process and Provenance

Journal of Petrology, 1991
Orogenic or alpine massifs comprise clinopyroxene-rich (lherzolite) and clinopyroxene-poor (harzburgite) peridotites with associated concordant (old) and discordant (young) mafic layers. The protolith is believed to be residual peridotite produced by partial melting processes in post-Archaean times and the mafic layers are interpreted as polybaric ...
M. A. Menzies, C. Dupuy
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Mineralogical characterization of protolith and fault rocks from the SAFOD Main Hole [PDF]

Geophysical Research Letters, 2006
Washed cuttings provide a continuous record of the rocks encountered during drilling of the main hole of the San Andreas Fault Observatory at Depth (SAFOD). Both protolith and fault rocks exhibit a wide variety of mineral assemblages that reflect variations in some combination of lithology, P‐T conditions, deformation mechanisms, and fluid composition ...
David A Lockner, Diane E Moore, Ben A Van Der Pluijm   +2 more
exaly   +6 more sources

Inherited 142Nd anomalies in Eoarchean protoliths

Earth and Planetary Science Letters, 2013
Abstract Geological records of the earliest history of the Earth are rare; rocks older than 3700 Ma comprise only a few percent of continental surfaces. Evidence is mounting, however, that vestiges of primordial planetary differentiation continued to influence the compositions of the oldest rocks during the Hadean and into the Archean.
Roth, Antoine S.G., Bourdon, Bernard, Mojzsis, Stephen, Touboul, Mathieu, Sprung, Peter, Guitreau, Martin, Blichert-Toft, Janne   +6 more
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Komsomolskaya diamondiferous eclogites: evidence for oceanic crustal protoliths

Contributions to Mineralogy and Petrology, 2014
The Komsomolskaya kimberlite is one of numerous (>1,000) kimberlite pipes that host eclogite xenoliths on the Siberian craton. Eclogite xenoliths from the adjacent Udachnaya kimberlite pipe have previously been geochemically well characterized; however, data from surrounding diamond-bearing kimberlite pipes from the center of the craton are relatively ...
Pernet-Fisher, John F., Howarth, Geoffrey H., Liu, Yang, Barry, Peter H., Carmody, Laura, Valley, John W., Bodnar, Robert J., Spetsius, Zdislav V., Taylor, Lawrence A.   +8 more
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Metamorphic zircon formation by solid-state recrystallization of protolith igneous zircon

Journal of Metamorphic Geology, 2000
Protolith zircon in high‐grade metagranitoids from Queensland, Australia, partially recrystallized during granulite‐grade metamorphism. We describe the zircon in detail using integrated cathodoluminescence, U–Pb isotope, trace element and electron backscatter diffraction pattern (EBSP) analyses.
P.W.O. Hoskin, L.P. Black
exaly   +2 more sources

Protolith age of eclogites from the southern part of Pezhostrov Island, Belomorian belt: Protolith of metabasites as indicator of eclogitization time

Petrology, 2016
Several types of metabasites of different age were identified in the southern part of Pezhostrov Island: eclogites with a magmatic protolith age of about 2200 Ma and 2500 Ma old metagabbroanorthosites that retained no eclogitic assemblage. It is shown that the Paleoproterozoic eclogites dominate volumetrically over Archean eclogites in the Belomorian ...
S. G. Skublov, A. V. Berezin, A. E. Melnik, B. Yu. Astafiev, O. A. Voinova, V. I. Alekseev   +5 more
exaly   +2 more sources

Melt production during granulite-facies anatexis: experimental data from "primitive" metasedimentary protoliths

Contributions to Mineralogy and Petrology, 1997
We conducted fluid-absent partial melting experiments, at 0.5 and 1.0 GPa in the temperature range 750 to 1000°C, to investigate the influence of bulk rock Mg# [100Mg/(Mg+ Fe)] and the effects of additional TiO2 on the granulite-grade anatectic evolution of relatively magnesian metapelites and metagreywackes. In these experiments, melting began between
Stevens, Gary, Clemens, John D., Droop, Giles T R   +2 more
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Highly siderophile element abundances in Eoarchean komatiite and basalt protoliths

Contributions to Mineralogy and Petrology, 2016
Plume-derived, Mg-rich, volcanic rocks (komatiites, high-Mg basalts, and their metamorphic equivalents) can record secular changes in the highly siderophile element (HSE) abundances of mantle sources. An apparent secular time-dependent enrichment trend in HSE abundances from Paleoarchean to Paleoproterozoic mantle-derived rocks could represent the ...
Elizabeth A. Frank, Wolfgang D. Maier, Stephen J. Mojzsis   +2 more
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New evidence for protolith ages of Lewisian granulites, northwest Scotland

Geology, 1995
The granulite facies Scourian rocks in the central region of the Lewisian complex of northwest Scotland play an important role in the understanding of the development of mid-Archean high-grade gneiss complexes. Whereas the later, largely Proterozoic history of the Scourian has been clarified in a detailed U-Pb study, unraveling the Archean ages of the ...
C. R. L. Friend, P. D. Kinny
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Geochemical signatures for eclogite protolith from the Maksyutov Complex, South Urals

Journal of Asian Earth Sciences, 2004
Abstract We conducted a geochemical study of eclogites (40 samples) from a boudin of the Lower Unit of the Maksyutov Complex in the South Urals in order to determine their protolith nature. The eclogites have major element compositions corresponding to quartz-bearing hypersthene basalts.
N.I. Volkova, A.E. Frenkel, V.I. Budanov, G.G. Lepezin   +3 more
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