Tungsten-182 evidence for an ancient kimberlite source
Nao Nakanishi, Andrea Giuliani, Richard W Carlson, Mary F Horan, Jon Woodhead, D Graham Pearson, Richard J Walker
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA | NATL ACAD SCIENCES | Published : 2021
Globally distributed kimberlites with broadly chondritic initial 143Nd-176Hf isotopic systematics may be derived from a chemically homogenous, relatively primitive mantle source that remained isolated from the convecting mantle for much of the Earth's history. To assess whether this putative reservoir may have preserved remnants of an early Earth process, we report 182W/184W and 142Nd/144Nd data for "primitive" kimberlites from 10 localities worldwide, ranging in age from 1,153 to 89 Ma. Most are characterized by homogeneous μ182W and μ142Nd values averaging -5.9 ± 3.6 ppm (2SD, n = 13) and +2.7 ± 2.9 ppm (2SD, n = 6), respectively. The remarkably uniform yet modestly negative μ182W values, ..View full abstract
Awarded by NSF
Support for this study was provided by NSF Grant EAR-1624587 (to R.J.W.). We thank two anonymous reviewers for their helpful comments. We also thank Roland Maas and Alan Greig for analytical support and Tetsuya Yokoyama, Katherine R. Bermingham, and Valerie A. Finlayson for helpful discussions.