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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The continental lithosphere–asthenosphere boundary: Can we sample it?
TL;DR: The lithosphere-asthenosphere boundary (LAB) represents the base of the Earth's lithosphere, the rigid and relatively cool outer shell characterised by a conductive thermal regime, isolated from the convecting asthenosphere as mentioned in this paper.
Journal ArticleDOI
Late Archean to Early Proterozoic lithospheric mantle beneath the western North China craton: Sr Nd Os isotopes of peridotite xenoliths from Yangyuan and Fansi
TL;DR: In this paper, peridotite xenoliths from Tertiary alkali basalts in Yangyuan and Fansi were analyzed for identifying and characterizing the relics of ancient lithospheric mantle that survived lithosphere removal in the western North China Craton (NCC).
Journal ArticleDOI
Application of the Pt–Re–Os isotopic systems to mantle geochemistry and geochronology
TL;DR: The Re-Os system has been applied to a wide variety of problems in the solid earth sciences as mentioned in this paper, such as understanding the age and composition of the mantle and the role that various materials in the mantle play in generating surface magmas.
Journal ArticleDOI
On the recovery of effective elastic thickness using spectral methods: Examples from synthetic data and from the Fennoscandian Shield
TL;DR: In this article, the authors investigate the long-term strength of continents from coherence and admittance, and show that the discrepancies stem from comparison of theoretical curves to multitaper power spectral estimates of free-air admittance.
Journal ArticleDOI
Re–Os isotopes of sulfides in mantle xenoliths from eastern China: Progressive modification of lithospheric mantle
Xisheng Xu,Xisheng Xu,William L. Griffin,Suzanne Y. O'Reilly,Norman J. Pearson,Hongyan Geng,Jianping Zheng +6 more
TL;DR: In situ Re-Os isotopic data for sulfide grains in mantle-derived peridotite xenoliths from eastern China demonstrate a close temporal linkage between crustal tectonism and fluid-migration events in the subcontinental lithospheric mantle (SCLM).
References
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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.
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Geothermobarometry in Four-phase Lherzolites II. New Thermobarometers, and Practical Assessment of Existing Thermobarometers
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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.
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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.