Lead isotopes in mantle derived xenoliths from Japan and South Africa

The lead isotopic compositions and the uranium, thorium and lead contents of eclogite and harzburgite inclusions from South African kimberlite-pipes and lherzolite inclusions from Itinomegata crater, Japan and of their main mineral fractions have been determined. The observed 206Pb/204Pb, 207Pb/204Pb and 235U/204Pb in lherzolite samples from Itinomegata range from 17.9 to 18.2, from 15.1 to 15.5 and from 1.9 to 23, respectively. The results suggest that the lherzolites were of recent crystallization. The observed data on eclogite inclusions show no consistent pattern and suggest that they have a complicated history. The observed lead isotopic compositions of harzburgite inclusions from kimberlitepipes are 208Pb/204Pb = 17.3 ∼ 19.0 and 207Pb/204Pb = 15.3 ∼ 15.6. These results are distributed in a wide range on two regression lines, suggesting that they had been formed from the same source material but with different ages or have been formed recently by mixing of two different source materials and host rock of kimberlite.

[1]  J. Kramers.  Lead and strontium isotopes in Cretaceous kimberlites and mantle-derived xenoliths from Southern Africa , 1977 .

[2]  M. Morioka,et al.  Lead isotopes and age of Hawaiian lherzolite nodules , 1975 .

[3]  I. L. Barnes,et al.  Lead separation by anodic deposition and isotope ratio mass spectrometry of microgram and smaller samples , 1973 .

[4]  M. Tatsumoto,et al.  Time Differences in the Formation of Meteorites as Determined from the Ratio of Lead-207 to Lead-206 , 1973, Science.

[5]  J. Mattinson.  Preparation of hydrofluoric, hydrochloric, and nitric acids at ultralow lead levels , 1972 .

[6]  K. Kigoshi.  Alpha-Recoil Thorium-234: Dissolution into Water and the Uranium-234/Uranium-238 Disequilibrium in Nature , 1971, Science.

[7]  W. Manton,et al.  Some Pb and Sr isotopic measurements on eclogites from the Roberts Victor mine, South Africa , 1971 .

[8]  A. H. Jaffey,et al.  Precision Measurement of Half-Lives and Specific Activities of U-235 and U238 , 1971 .

[9]  Dennis H. Smith,et al.  Mass spectrometry of nanogram-size samples of lead , 1969 .

[10]  J. Lovering,et al.  LEAD ISOTOPES AND THE ORIGIN OF GRANULITE AND ECLOGITE INCLUSIONS IN DEEP- SEATED PIPES. , 1968 .

[11]  H. Wakita,et al.  Rare earths in peridotite nodules: An explanation of the genetic relationship between basalt and peridotite nodules , 1968 .

[12]  T. Ulrych.  Oceanic Basalt Leads: A New Interpretation and an Independent Age for the Earth , 1967, Science.

[13]  H. Wakita,et al.  URANIUM, THORIUM, AND POTASSIUM CONTENTS OF POSSIBLE MANTLE MATERIALS. , 1967 .

[14]  R. White.  Ultramafic inclusions in basaltic rocks from Hawaii , 1966 .

[15]  J. Richards,et al.  Lead isotopes and volcanic magmas , 1966 .

[16]  M. Tatsumoto.  Isotopic composition of lead in volcanic rocks from Hawaii, Iwo Jima, and Japan , 1966 .

[17]  I. Kushiro,et al.  Origin of Primary Basalt Magmas and Classification of Basaltic Rocks , 1963 .

[18]  H. Müller.  Neue Untersuchungen über die Mikro-Verfahren zur Bleibestimmung mittels Elektrolyse und Dithizon , 1938 .