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Science 17 December 1993:
Vol. 262. no. 5141, pp. 1861 - 1863
DOI: 10.1126/science.262.5141.1861
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Articles

Orphan Strontium-87 in Abyssal Peridotites: Daddy Was a Granite

Jonathan E. Snow 1, Stanley R. Hart 1, and Henry J. B. Dick 1

1 Woods Hole Oceanographic Institution, Woods Hole, MA 02143

The 87Sr/86Sr ratios in some bulk abyssal and alpine peridotites are too high to be binary mixtures of depleted mantle and seawater components. The apparent excess, or "orphan," 87Sr appears to be separated from its radioactive parent. Such observations were widely held to be analytical artifacts. Study of several occurrences of orphan 87Sr shows that the orphan component in abyssal peridotite is located in the alteration products of olivine and enstatite in the peridotite. The orphan 87Sr is most likely introduced by infiltration of low-temperature (<200°C) seawater bearing suspended detrital particulates. These particulates include grains of detrital clay that are partly derived from continental (that is, granitic) sources and thus are highly radiogenic. Orphan 87Sr and other radiogenic isotopes may provide a tracer for low-temperature seawater penetrating into the oceanic crust.

Submitted on June 22, 1993
Accepted on October 15, 1993


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Contrasting Group I and Group II Eclogite Xenolith Petrogenesis: Petrological, Trace Element and Isotopic Evidence from Eclogite, Garnet-Websterite and Alkremite Xenoliths in the Kaalvallei Kimberlite, South Africa.
K. S. VILJOEN, D. J. SCHULZE, and A. G. QUADLING (2005)
J. Petrology 46, 2059-2090
   Abstract »    Full Text »    PDF »
Bulk-rock Major and Trace Element Compositions of Abyssal Peridotites: Implications for Mantle Melting, Melt Extraction and Post-melting Processes Beneath Mid-Ocean Ridges.
Y. NIU (2004)
J. Petrology 45, 2423-2458
   Abstract »    Full Text »    PDF »
Oceanic crust generated by elusive parents: Sr and Nd isotopes in basalt-peridotite pairs from the Mid-Atlantic Ridge.
(2004)
Geology 32, 657-660


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Science. ISSN 0036-8075 (print), 1095-9203 (online)