Back to Search
Start Over
Hadean geodynamics inferred from time-varying 142 Nd/ 144 Nd in the early Earth rock record.
- Source :
-
Geochemical perspectives letters [Geochem Perspect Lett] 2018 Sep 05; Vol. 7, pp. 43-48. - Publication Year :
- 2018
-
Abstract
- Tracking the secular evolution of <superscript>142</superscript> Nd/ <superscript>144</superscript> Nd 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 <superscript>142</superscript> Nd/ <superscript>144</superscript> Nd evolution as the expected variability is on the order of few parts per million. We report ultra-high precision <superscript>142</superscript> Nd/ <superscript>144</superscript> Nd data for Eoarchean and Palaeoarchean rocks from the Isua Supracrustal Belt (SW Greenland) that show a well-resolved <superscript>142</superscript> Nd/ <superscript>144</superscript> Nd temporal variability suggesting progressive convective homogenisation of the Hadean Isua depleted mantle. This temporally decreasing <superscript>142</superscript> Nd/ <superscript>144</superscript> Nd 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 <superscript>142</superscript> Nd/ <superscript>144</superscript> Nd 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.
Details
- Language :
- English
- ISSN :
- 2410-339X
- Volume :
- 7
- Database :
- MEDLINE
- Journal :
- Geochemical perspectives letters
- Publication Type :
- Academic Journal
- Accession number :
- 33073040
- Full Text :
- https://doi.org/10.7185/geochemlet.1818