- Award ID(s):
- 1944602
- NSF-PAR ID:
- 10320900
- Date Published:
- Journal Name:
- IEEE Journal of Solid-State Circuits
- Volume:
- 57
- Issue:
- 3
- ISSN:
- 0018-9200
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract The evolution of Earth's major geochemical reservoirs over ~4.5 × 109 years remains a matter of intense study. Geochemical tools in the form of short‐lived radionuclide isotope ratios (142Nd/144Nd and182W/184W) have expanded our understanding of the geochemical variability in both the modern and ancient Earth. Here, we present142Nd/144Nd and182W/184W data from a suite of rocks from the Slave craton that formed over a 1.1 × 109 year time span in the Archean. The rocks have consistently high182W/184W, yet142Nd/144Nd that is lower than bulk mantle and increased over time. The declining variability in142Nd/144Nd with time likely reflects the homogenization of compositional heterogeneities in the silicate Earth that were initially created by differentiation events that occurred prior to 4.2 Ga. The elevated182W/184W recorded in the Slave samples help refine models for the broader W‐isotope evolution of the silicate Earth. Globally, the Archean mantle that formed continental crust was dominated by182W/184W elevated by some 10–15 ppm compared to the value for the modern upper mantle. The Slave craton lacks significant volumes of komatiite yet has elevated182W/184W until 2.9 Ga. This observation, combined with the presence of other komatiite suites that have low182W/184W, suggests that deep‐seated sources contributed low182W/184W in the Archean Earth. The regional variability in182W/184W may be explained by invoking chemical and/or isotopic exchange between a well‐mixed silicate Earth and the core or a portion of the lower mantle whose W‐isotope composition has been influenced by interaction with the core.