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
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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
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Seismic evidence for the stratified lithosphere in the south of the North China Craton
Pan Wang,Mingjie Xu,Liangshu Wang,Ning Mi,Dayong Yu,Hua Li,Cheng Li,Xuewei Bao,Tao Huang,Hui Huang +9 more
TL;DR: In this article, the authors investigated the upper mantle structures in the southern North China Craton (NCC) by using receiver functions analysis, and the seismic images showed significant stratified structures in upper mantle in the south of the NCC.
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In search for the missing arc root of the Southern California Batholith: P-T-t evolution of upper mantle xenoliths of the Colorado Plateau Transition Zone
Ojashvi Rautela,Alan D. Chapman,Jessie E. Shields,Mihai N. Ducea,Mihai N. Ducea,Cin Ty Lee,Hehe Jiang,Jason B. Saleeby +7 more
TL;DR: In this article, the authors show that the CPTZ arclogite originates from beneath the eastern half of the southern California batholith (SCB), where it began forming in Late Jurassic time as mafic keel to continental arc magmas.
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Geochemical constraints on mantle-melt sources for Oligocene to Pleistocene mafic rocks in the Four Corners region, USA
David A. Gonzales,Ethan T. Lake +1 more
TL;DR: In this article, the authors show that post-26-million-year mantle melts produced in the Four Corners region were heterogeneous in composition, dominantly alkaline, and distinguished by trace-element patterns with elevated LILE and LREE.
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Exploring the theory of plate tectonics: the role of mantle lithosphere structure
TL;DR: Wilson et al. as mentioned in this paper presented the Fifty years of the Wilson Cycle concept in plate tectonics and applied it to the GPC supercomputer at the SciNet HPC Consortium.
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U–Pb–Hf–O–Nd isotopic and geochemical constraints on the origin of Archean TTG gneisses from the North China Craton: Implications for crustal growth
TL;DR: In this paper, the authors have carried out field observations, zircon U-Pb-Hf-O isotope and geochemical analyses on the TTG and associated dioritic gneisses from the North China Craton, showing that the geochemistry of TTG might be affected by complex petrogenetic processes, i.e., partial melting of individual sources, magma mixing, fractional crystallization, and crustal contamination.
References
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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.
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Geothermobarometry in Four-phase Lherzolites II. New Thermobarometers, and Practical Assessment of Existing Thermobarometers
Gerhard P. Brey,T. Köhler +1 more
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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.
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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.