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Hadean geodynamics ...
Hadean geodynamics inferred from time-varying 142Nd/144Nd in the early Earth rock record
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Saji, N. S. (author)
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Larsen, K. (author)
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Wielandt, D. (author)
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Schiller, M. (author)
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Costa, M. M. (author)
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- Whitehouse, Martin J., 1962- (author)
- Naturhistoriska riksmuseet,Enheten för geovetenskap,Nordsim
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Rosing, M. T. (author)
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Bizzarro, M. (author)
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(creator_code:org_t)
- 2018
- 2018
- English.
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In: Geochemical Perspectives Letters. ; 7, s. 43-48
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https://nrm.diva-por... (primary) (Raw object)
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Abstract
Subject headings
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- Tracking the secular evolution of 142Nd/144Nd anomalies is important towards understanding the crust-mantle dynamics in the early Earth. Excessive scatter in the published data, however, precludes identifying the fine structure of 142Nd/144Nd evolution as the expected variability is on the order of few parts per million. We report ultra-high precision 142Nd/144Nd data for Eoarchean and Palaeoarchean rocks from the Isua Supracrustal Belt (SW Greenland) that show a well-resolved 142Nd/144Nd temporal variability suggesting progressive convective homogenisation of the Hadean Isua depleted mantle. This temporally decreasing 142Nd/144Nd signal provides a direct measure of early mantle dynamics, defining a stirring timescale of <250 Myr consistent with vigorous convective stirring in the early mantle. The 142Nd/144Nd evolution suggests protracted crustal residence times of ~1000-2000 Myr, inconsistent with modern-style plate tectonics in the Archean. In contrast, a stagnant-lid regime punctuated by episodes of mantle overturns accounts for the long life-time estimated here for the Hadean proto-crust.
Subject headings
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Geokemi (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Geochemistry (hsv//eng)
Keyword
- The changing Earth
- Den föränderliga jorden
Publication and Content Type
- ref (subject category)
- art (subject category)
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