Measurements of ¹⁴²Nd isotope signatures in Archean rocks are a powerful tool to investigate the earliest silicate differentiation events on Earth. Here, we introduce a new analytical protocol that allows high precision radiogenic and mass-independent Nd isotope measurements by MC-ICP-MS. To validate our method, we have measured well-characterized ∼3.72 to ∼3.8 Ga samples from the Eoarchean Itsaq Gneiss Complex and associated supracrustal belts, as well as Mesoarchean greenstones and a Proterozoic dike in SW Greenland, including lithostratigraphic units that were previously analyzed for ^142-143Nd isotope systematics, by both TIMS and MC-ICP-MS. Our μ¹⁴²Nd values for ∼3.72 to ∼3.8 Ga rocks from the Isua region range from +9.2 ± 2.6 to +13.2 ± 1.1 ppm and are in good agreement with previous studies. Using coupled ^142,143Nd/¹⁴⁴Nd isotope systematics from our data for ∼3.8 Ga mafic-ultramafic successions from the Isua region, we can confirm previous age constraints on the earliest silicate differentiation events with differentiation age of 4.390_−0.060^+0.045 Ga. Moreover, we can resolve a statistically significant decrease of ¹⁴²Nd/¹⁴⁴Nd isotope compositions in the ambient mantle of SW Greenland that already started to commence by Eoarchean time, between ∼3.8 Ga (μ¹⁴²Nd = +13.0 ± 1.1) and ∼ 3.72 Ga (μ¹⁴²Nd = +9.8 ± 1.0). Even lower but homogeneous μ¹⁴²Nd values of +3.8 ± 1.1 are found in ∼3.4 Ga mantle-derived rocks from the Ameralik dike swarms. Our study reveals that ε¹⁴³Nd_(i) and εHf_(i) values of Isua rocks scatter more than it would be expected from a single stage differentiation event as implied from nearly uniform μ¹⁴²Nd values, suggesting that the previously described decoupling of Hf and Nd isotopes is not a primordial magma ocean signature. Instead, we conclude that some of second stage processes like younger mantle depletion events or recycling of subducted material affected the ¹⁴⁷Sm[sbnd]¹⁴³Nd isotope systematics. The preservation of pristine whole-rock isochrons largely rules out a significant disturbance by younger alteration events. Based on isotope and trace element modelling, we argue that the temporal evolution of coupled ^142,143Nd/¹⁴⁴Nd isotope compositions in the ambient mantle beneath the Isua rocks is best explained by the progressive admixture of material to the Isua mantle source that must have had present-day-like μ¹⁴²Nd compositions. In contrast, Mesoarchean mafic rocks from the ∼3.08 Ga Ivisaartoq greenstone belt and the 2.97 Ga inner Ameralik Fjord region as well as a 2.0 Ga Proterozoic dike within that region all have higher μ¹⁴²Nd values as would be expected from our simple replenishment model. This argues for reworking of older Isua crustal material that carried elevated μ¹⁴²Nd compositions.