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Tracking Hadean Chemical Domains in Time and Space using Neodymium-142 Isotopic Signatures Measured from southwest Greenland Terranes

Variations in 142 Nd isotopic compositions in terrestrial rocks record chemical fractionation events (changes in trace element patterns, i.e. Sm/Nd ratios) occurring within the first ca. 400 myr of solar system history, that is whilst the parent isotope 146 Sm (t 1/2 = 103 myr) was actively decaying. The preservation of these Hadean formed isotopic anomalies in younger rocks thus provides a powerful tracer of geologic processes associated with the formation and destruction of early mantle chemical reservoirs. Moreover, 142 Nd isotopic signatures are largely impervious to secondary alternation events. To investigate further the 142 Nd record in time and space we have determined precise isotopic compositions using multidynamic TIMS measurements for geographically, compositionally and chronologically diverse samples from terranes across southwest Greenland. This builds on previous, more restricted work, focussed largely on the 3.7-3.8Ga Isua supracrustal belt. The new data are from samples ranging in age from ca. 3.0 to 3.9 Ga and include regional 3.2 Ga to 3.5 Ga mafic dyke swarms (Nutman et al, 2004). The samples are regionally extensive including from newly-dated Archean nunataks within the inland ice (Nutman, 2021). The analysed samples are compositionally diverse including rare Eoarchean gabbros with MORB-like trace element compositions. The 142 Nd isotopic anomalies are from 0 to +19 ppm relative to