Journal ArticleDOI
Preservation of ancient and fertile lithospheric mantle beneath the southwestern United States.
Cin-Ty A. Lee,Cin-Ty A. Lee,Qing-Zhu Yin,Roberta L. Rudnick,Roberta L. Rudnick,Stein B. Jacobsen +5 more
TLDR
It is suggested that depleted mantle is intrinsically less dense than fertile mantle (due to iron having been lost when melt was extracted from the rock), which allows the depleted mantle to form a thicker thermal boundary layer between the deep convecting mantle and the crust, thus reducing tectonic activity at the surface.Abstract:
Stable continental regions, free from tectonic activity, are generally found only within ancient cratons—the centres of continents which formed in the Archaean era, 4.0–2.5 Gyr ago. But in the Cordilleran mountain belt of western North America some younger (middle Proterozoic) regions have remained stable, whereas some older (late Archaean) regions have been tectonically disturbed, suggesting that age alone does not determine lithospheric strength and crustal stability. Here we report rhenium–osmium isotope and mineral compositions of peridotite xenoliths from two regions of the Cordilleran mountain belt. We found that the younger, undeformed Colorado plateau is underlain by lithospheric mantle that is 'depleted' (deficient in minerals extracted by partial melting of the rock), whereas the older (Archaean), yet deformed, southern Basin and Range province is underlain by 'fertile' lithospheric mantle (not depleted by melt extraction). We suggest that the apparent relationship between composition and lithospheric strength, inferred from different degrees of crustal deformation, occurs because depleted mantle is intrinsically less dense than fertile mantle (due to iron having been lost when melt was extracted from the rock). This allows the depleted mantle to form a thicker thermal boundary layer between the deep convecting mantle and the crust, thus reducing tectonic activity at the surface. The inference that not all Archaean crust developed a strong and thick thermal boundary layer leads to the possibility that such ancient crust may have been overlooked because of its intensive reworking or lost from the geological record owing to preferential recycling.read more
Citations
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Journal ArticleDOI
Re-Os evidence for replacement of ancient mantle lithosphere beneath the North China Craton
TL;DR: In this paper, peridotite xenoliths carried in Paleozoic kimberlites and Tertiary alkali basalts confirm previous suggestions that the refractory and chemically buoyant lithospheric keel present beneath the eastern block of the North China craton is indeed Archean in age.
Journal ArticleDOI
Constraints on the depths and temperatures of basaltic magma generation on Earth and other terrestrial planets using new thermobarometers for mafic magmas
TL;DR: In this article, a thermobarometer based on magma Si and Mg contents was used to estimate the pressures and temperatures of basaltic magma generation on Earth and other terrestrial planets.
Book ChapterDOI
Mantle Samples Included in Volcanic Rocks: Xenoliths and Diamonds
TL;DR: A review of the geochemistry of mantle xenoliths can be found in this article, where the authors review the geochemical properties of mantle nodules and find that they are dominantly alkaline in nature.
Journal ArticleDOI
Petrology and geochemistry of spinel peridotite xenoliths from Hannuoba and Qixia, North China craton
TL;DR: In this article, mineralogical and chemical compositions of spinel peridotite xenoliths from two Tertiary alkali basalt localities on the Archean North China craton (Hannuoba and Qixia) were reported.
Journal ArticleDOI
Physical, chemical, and chronological characteristics of continental mantle
TL;DR: The sub-crustal mantle as discussed by the authors consists of a thick section of material left behind after extensive partial melt extraction, possibly from the wedge of mantle overlying a subducting oceanic plate.
References
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Journal ArticleDOI
The composition of the Earth
William F. McDonough,Shen-Su Sun +1 more
TL;DR: In this paper, the authors compared the relative abundances of the refractory elements in carbonaceous, ordinary, and enstatite chondritic meteorites and found that the most consistent composition of the Earth's core is derived from the seismic profile and its interpretation, compared with primitive meteorites, and chemical and petrological models of peridotite-basalt melting relationships.
Journal ArticleDOI
Geothermobarometry in Four-phase Lherzolites II. New Thermobarometers, and Practical Assessment of Existing Thermobarometers
Gerhard P. Brey,T. Köhler +1 more
Journal ArticleDOI
Composition and development of the continental tectosphere
TL;DR: In this article, the Wilson cycle is used to balance the tectosphere by depleting the continental upper mantle in a basalt-like component, which stabilizes the old continental nuclei against convective disruption.
Journal ArticleDOI
Os, Sr, Nd, and Pb isotope systematics of southern African peridotite xenoliths: Implications for the chemical evolution of subcontinental mantle
TL;DR: Isotope analyses of Os, Sr, Nd, and Pb elements were caried out on twelve peridotite xenoliths from the Jagersfontein, Letseng-la-terae, Thaba Patsoa, Mothae, and Premier kimberlites of southern Africa, to investigate the timing and the nature of melt extraction from the continental lithosphere and its relation to the continent formation and stabilization.
Journal ArticleDOI
Proterozoic crustal history of the western United States as determined by neodymium isotopic mapping
TL;DR: In this article, three age provinces have been delineated, each generally northeast-southwest trending, having decreasing crystallization ages and increasing initial e nd values with increasing distance southeastward from the Archean craton.