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Unradiogenic lead in Earth’s upper mantle
- Source :
- Nature Geoscience, Nature Geoscience, 2012, 5, pp.570-573. ⟨10.1038/ngeo1531⟩, Nature Geoscience, Nature Publishing Group, 2012, 5, pp.570-573. ⟨10.1038/ngeo1531⟩
- Publication Year :
- 2012
- Publisher :
- Springer Science and Business Media LLC, 2012.
-
Abstract
- International audience; The mantle and continental crust--Earth's main silicate reservoirs--have a lead isotope composition that is too radiogenic to have evolved from primitive Solar System material over 4.57 billion years1. To account for this imbalance, it has been suggested that unradiogenic lead may have partitioned into the metallic core2, 3, 4 or lower continental crust5. Alternatively, radiogenic lead could have been added to Earth later by meteorite impacts6. Unradiogenic lead was discovered in fragments of mantle rocks exhumed in the Horoman massif, Japan, implying that the mantle itself may provide a complementary reservoir of unradiogenic lead7. However, it is unclear why this unradiogenic component is not sampled by the melting that generates oceanic basalts8. Here we present double-spike lead isotope data for abyssal peridotite rocks, considered to represent suboceanic mantle, exposed on the Atlantic Ocean floor. We find that sulphides dated at about 1.83 billion years old and trapped as inclusions in silicate minerals preserve extremely unradiogenic lead isotope compositions. This unradiogenic lead could have been prevented from adding significantly to oceanic basalts if either the silicates shield the sulphide inclusions or if the sulphides reside in refractory mantle rocks that are rarely sampled during melting. We conclude that the lead isotope composition of the silicate Earth could be largely balanced by unradiogenic lead in sulphide in the mantle.
- Subjects :
- Radiogenic nuclide
010504 meteorology & atmospheric sciences
[SDE.MCG]Environmental Sciences/Global Changes
Continental crust
Geochemistry
Volcanology
010502 geochemistry & geophysics
01 natural sciences
Mantle (geology)
[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry
13. Climate action
General Earth and Planetary Sciences
Structural geology
Seabed
Geology
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 17520908 and 17520894
- Volume :
- 5
- Database :
- OpenAIRE
- Journal :
- Nature Geoscience
- Accession number :
- edsair.doi.dedup.....5e55522e0c5728b9f0b00b98f6b38420