Lead-lead age of komatiitic lavas and limitations on the structure and evolution of the Precambrian mantle

Details Lead-lead age of komatiitic lavas and limitations on the structure and evolution of the Precambrian mantle Lead-lead age of komatiitic lavas and limitations on the structure and evolution of the Precambrian mantle

Apr 1986

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1986e%26psl..77..293b&link_type=abstract

Earth and Planetary Science Letters (ISSN 0012-821X), vol. 77, no. 3-4, April 1986, p. 293-302.

Other

28

Earth Mantle, Geochronology, Lava, Lead Isotopes, Planetary Evolution, Precambrian Period, Abundance, Basalt, Earth Planetary Structure, Petrology, Republic Of South Africa, Uranium

Scientific paper

Using lead isotopes, komatiites and associated sulfides from three complexes were studied. At Barberton, the lead-lead isochron gives an age of 3.46 + or - 0.07 Gy in good agreement with the Sm-Nd age. At Munro Township, three distinct komatiitic flows yield significantly different ages: Pyke Hill is 2.72 + or - 0.02 Gy, Theo's flow is 2.47 + or - 0.13 Gy and Fred's Flow is 2.58 + or - 0.02 Gy old. 2.72 Gy is the emplacement age while the alignment obtained on Theo's Flow and Fred's Flow clearly points out the effect of a metamorphism posterior to 2.7 Gy. At Cape Smith, the age obtained by the lead-lead method is 1.6 + or - 0.13 Gy. This age is younger than that obtained by other methods. In contrast the isochron obtained on sulfide gives an age of 1.88 + or - 0.17 Gy in agreement with Sm/Nd methods. These results together with others from the literature are used to describe the evolution of Pb in the mantle. The important result inferred is that the mantle 2.70 Gy ago was very different from the primitive mantle according to both Th/U and U/Pb values. Indeed, the latter are lower than the planetary values. This evolution is the result of the formation of the continental crust.

Affiliated with

Also associated with

No associations

Rating

Lead-lead age of komatiitic lavas and limitations on the structure and evolution of the Precambrian mantle does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Lead-lead age of komatiitic lavas and limitations on the structure and evolution of the Precambrian mantle, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lead-lead age of komatiitic lavas and limitations on the structure and evolution of the Precambrian mantle will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1102217