Mantle enrichment processes

Hawkesworth, Chris J.; Rogers, Nick; Calsteren, P. W. C. van; Menzies, Martin

doi:10.1038/311331a0

Cited by 239 publications

(62 citation statements)

References 65 publications

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“…However, Ba depletion has also been reported to be due to the presence of Ba-depleted sediment subductioncomponent at source (Smith et al, 1986). The high Ce/Yb and Th/Yb ratios (Table 1) relative to the primitive mantle of these rock suites also indicate selective enrichment of Th and Ce due to the invasion of fluid coming out from subducted slab (Hawkesworth et al, 1984;Peltonen, 1995). Depletion of Zr in N-MORB normalized plot (Fig.…”

Section: Resultsmentioning

confidence: 99%

Sm-Nd age and mantle source characteristics of the Dhanjori volcanic rocks, Eastern India.

et al. 2002

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Section: Resultsmentioning

confidence: 99%

Sm-Nd age and mantle source characteristics of the Dhanjori volcanic rocks, Eastern India.

et al. 2002

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“…The Dupal anomaly stretches in an almost continuous belt around the Southern Hemisphere between the equator and 60øS. Although not all basalts from within this belt exhibit a strong Dupal signature, 95% of all basalts that do show it lie between 0 ø and 50øS latitude [Hart, 1988] [Hawkesworth et al, 1984], and an asthenosphere plume origin [Hart, 1988, Castillo, 1988. Hart [1984] argued that the anomaly strongly constrains models of mantle convection.…”

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confidence: 99%

Quantifying mixing and age variations of heterogeneities in models of mantle convection: Role of depth‐dependent viscosity

Hunt

Kellogg

2001

J. Geophys. Res.

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Abstract. Using a two-dimensional finite element model of mantle convection containing over a million tracer particles, we examine the effects of depth-dependent viscosity on the rates and patterns of mixing. We sinrelate the processes of recycling crust at subduction zones and the homogenization of recycled material (by dispersion and by melting at mid-ocean ridges). Particles are continually introduced at dowmvellings and destroyed when they either are so thoroughly dispersed that it would be impossible to measure their presence in the geochemical signature of mid-ocean ridges or oceanic islands, or when they are close to spreading centers, at which point melting would "reset" the geochemical clock. A large number of factors influence the flow pattern and thus the rate at which heterogeneities are dispersed by convection. We examine the effect of increasing the viscosity with depth, and determine how both the residence time of heterogeneities and the extent of lateral mixing and exchange between the upper and lower mantle vary with the viscosity profile of the mantle. We determine the particle distribution resulting from convection models with three viscosity profiles: uniform viscosity, a smooth increase of viscosity with depth, and an abrupt jump in viscosity between the upper and lower mantle. We characterize the resulting distribution of heterogeneities in space and time by examining the age distribution of particles and their locations relative to others introduced into the flow at separate downwellings. Mixing rates in the three models are calculated as a function of the number of particles removed from the flow through time. We fbund that an increase of viscosity at depth does not induce age stratification in which older particles stagnate in the lower mantle, and it does not produce an upper layer (the source of mid-ocean ridge basalt) that is well-mixed compared to the deeper regions. However, pronounced lateral heterogeneity is evident in the distribution of particles of different ages and starting locations that is not apparent from the particle positions alone.

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“…On the other hand, and often the strongest criticism of the Standard Model (e.g. Hawkesworth et al, 1984;Barling and Goldstein, 1990;Morgan, 2000), is that there may be no such things as mantle endmembers. Each ocean island array could consist of its own unique isotopic composition, which represents a unique subducted slab from a unique recycling time.…”

Section: Introductionmentioning

confidence: 99%

“…fluidlmelt infiltration) of oceanic lithosphere, followed by subduction zone recycling and long-term storage of this lithosphere. As a process for creating trace-elementenriched mantle, metasomatism is not a new idea and has been invoked both for continental lithosphere (Frey and Green, 1974;., 1976; Menzies and Murthy, 1980;Menzies, 1983) and oceanic lithosphere (Zjndler et al, 1979;Kay, 1979;Hawkesworth et al, 1979Hawkesworth et al, , 1984Richardson et al ., 1982;Roden et al, 1984;Halliday et al, 1992;Class and Goldstein, 1997;Niu et al, 19%;1999;Niu and O'Hara, 2003). The process we envision is much like the SYS model of Zindler et al (1979), and the autometasomatic model of Roden et al (1984).…”

Section: Introductionmentioning

confidence: 99%

Geochemical characterization of endmember mantle components

Workman¹

2005

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Mantle enrichment processes

Cited by 239 publications

References 65 publications

Sm-Nd age and mantle source characteristics of the Dhanjori volcanic rocks, Eastern India.

Sm-Nd age and mantle source characteristics of the Dhanjori volcanic rocks, Eastern India.

Quantifying mixing and age variations of heterogeneities in models of mantle convection: Role of depth‐dependent viscosity

Geochemical characterization of endmember mantle components

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