Isotopic and chemical constraints on mantle-crust evolution

Conference · Wed Jun 01 00:00:00 EDT 1988 · Geochimica et Cosmochimica Acta; (USA)

OSTI ID:5398944

Jacobsen, S B ^[1]

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1. Harvard Univ., Cambridge, MA (USA)

A formalism for the general treatment of three-layer mantle-crust evolution models is presented and various published models are shown to be special cases of this more general model. The Sm-Nd, Lu-Hf, and Rb-Sr isotopic present day mass balance for the continental crust-depleted mantle systems is consistent with {approximately}30% of the mantle being depleted. A growth curve for the continental crust is calculated on the basis of total inversion of the Sm-Nd isotopic data for all of Earth history. The curve suggests that by about 3.8 Ga ago, {approximately}40% of the present continental volume was present. Both the estimated continental recycling and addition rates show maxima around 3.0 Ga. The resulting continental addition rates are also very high 4.5-4.0 Ga ago and during the Phanerozoic. The Sm-Nd data are not compatible with a steady state model for the crust over the past 2-3 Ga. The major uncertainty in evaluating crust-mantle evolution models is the extent of exchange between the upper and lower mantle.

• OSTI ID: 5398944
• Report Number(s): CONF-8703325-; CODEN: GCACA
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 52:6; Conference: Isotope tracers in geochemistry and geophysics, Pasadena, CA (USA), 23-25 Mar 1987; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CONTINENTAL CRUST
CHEMICAL COMPOSITION
GEOLOGIC MODELS
ORIGIN
EARTH MANTLE
EARTH PLANET
GEOCHEMISTRY
GEOLOGIC HISTORY
ISOTOPE DATING
ISOTOPE RATIO
MASS BALANCE
NEODYMIUM
PETROGENESIS
PLANETARY EVOLUTION
SAMARIUM
AGE ESTIMATION
CHEMISTRY
EARTH CRUST
ELEMENTS
METALS
PLANETS
RARE EARTHS
SOLAR SYSTEM EVOLUTION
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580300 - Mineralogy
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& Rock Mechanics- (-1989)