Pyroxenites embedded in peridotite are often invoked as a major cause of short-length scale isotopic heterogeneities in the upper mantle, but there has been little direct evidence. We report spatially controlled chemical and Sr-Nd isotopic compositions of pyroxenites and their host peridotites from an ophiolitic mantle sequence in the Northern Apennines, Italy, with depleted mantle compositions, representing a surface exposure of veined upper mantle, a potential source for mid-oceanic-ridge basalts (MORB). Interaction between pyroxenites and adjacent mantle rocks results in centimeter-scale chemical modifi cations in the host peridotites, systematically lowering their Sm/Nd ratios. Over time, this interaction causes the host peridotite at >0.1 m scale to acquire an isotopic heterogeneity larger than the range defi ned by the peridotite and pyroxenite end-members. Moreover, the 143Nd/144Nd variation of a single outcrop covers most of the global Nd isotopic variability documented in abyssal peridotites. Such pyroxenite-peridotite veined mantle domains may represent the enriched component rarely found in abyssal peridotites, but often invoked to account for the low end of 143Nd/144Nd variations in MORB.

Meter-scale Nd isotopic heterogeneity in pyroxenite-bearing Ligurian peridotites encompasses global-scale upper mantle variability / G., Borghini; E., Rampone; A., Zanetti; C., Class; Cipriani, Anna; A. W., Hofmann; S. L., Goldstein. - In: GEOLOGY. - ISSN 0091-7613. - ELETTRONICO. - 41:(2013), pp. 1055-1058. [10.1130/G34438.1]

Meter-scale Nd isotopic heterogeneity in pyroxenite-bearing Ligurian peridotites encompasses global-scale upper mantle variability

CIPRIANI, Anna;
2013

Abstract

Pyroxenites embedded in peridotite are often invoked as a major cause of short-length scale isotopic heterogeneities in the upper mantle, but there has been little direct evidence. We report spatially controlled chemical and Sr-Nd isotopic compositions of pyroxenites and their host peridotites from an ophiolitic mantle sequence in the Northern Apennines, Italy, with depleted mantle compositions, representing a surface exposure of veined upper mantle, a potential source for mid-oceanic-ridge basalts (MORB). Interaction between pyroxenites and adjacent mantle rocks results in centimeter-scale chemical modifi cations in the host peridotites, systematically lowering their Sm/Nd ratios. Over time, this interaction causes the host peridotite at >0.1 m scale to acquire an isotopic heterogeneity larger than the range defi ned by the peridotite and pyroxenite end-members. Moreover, the 143Nd/144Nd variation of a single outcrop covers most of the global Nd isotopic variability documented in abyssal peridotites. Such pyroxenite-peridotite veined mantle domains may represent the enriched component rarely found in abyssal peridotites, but often invoked to account for the low end of 143Nd/144Nd variations in MORB.
2013
41
1055
1058
Meter-scale Nd isotopic heterogeneity in pyroxenite-bearing Ligurian peridotites encompasses global-scale upper mantle variability / G., Borghini; E., Rampone; A., Zanetti; C., Class; Cipriani, Anna; A. W., Hofmann; S. L., Goldstein. - In: GEOLOGY. - ISSN 0091-7613. - ELETTRONICO. - 41:(2013), pp. 1055-1058. [10.1130/G34438.1]
G., Borghini; E., Rampone; A., Zanetti; C., Class; Cipriani, Anna; A. W., Hofmann; S. L., Goldstein
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/979775
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