Journal article

ANCIENT SEAFLOOR SIGNALS IN PITCAIRN-ISLAND LAVAS AND EVIDENCE FOR LARGE-AMPLITUDE, SMALL LENGTH-SCALE MANTLE HETEROGENEITIES

JD WOODHEAD, MT MCCULLOCH

EARTH AND PLANETARY SCIENCE LETTERS | ELSEVIER SCIENCE BV | Published : 1989

Abstract

Isotopic data for Pitcairn island volcanic rocks reveal the presence of two markedly different sources which appear to be closely related both spatially and temporally. The isotopic variability (or amplitude ratio) of this suite relative to all other oceanic basalts (mid-ocean ridges and oceanic islands) is ∼ 30% for Pb, ∼ 40% for Sr and 50% for Nd. This confirms the findings of several recent studies indicating that, contrary to earlier conclusions, large amplitude variations can exist over limited (∼ 10 km) length scales. The unusual, unradiogenic 206Pb/204Pb and 143Nd/144Nd and radiogenic 87Sr/86Sr isotopic compositions, lack of strong covariation between isotopic and other geochemical pa..

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