M.J. Whitehouse 1988 <p><span>A published Sm–Nd whole-rock isochron of 2,920 ± 50 Myr, obtained from a wide range of lithologies in the Lewisian complex of north-west Scotland, was interpreted</span>¹<span>&nbsp;as the time of protolith formation. This date is&nbsp;</span><span class="stix">∼</span><span>260 Myr older than estimates for the timing of high-grade metamorphism in the complex at&nbsp;</span><span class="stix">∼</span><span>&nbsp;2,660 Myr</span>^2'3<span>, and this period is considered to represent the duration of the Lewisian crustal accretion-differentiation superevent (CADS)</span>⁴<span>. Here we give new Sm-Nd data, obtained specifically from granulite facies tonalitic gneisses, that yield a date of 2,600 ±155 Myr. Although depleted-mantle model ages (</span><i>t</i><span>DM suggest &gt;200 Myr of premetamorphic crustal residence, the regression date and its associated initial Nd-isotopic parameters demonstrate Nd-isotopic homogenization during the high-grade event, as well as the probability of general rare-earth-element (REE) mobility. Models for selective element depletion in the complex have previously assumed REE immobility since 2,920 Myr, but the data presented here suggest that a reappraisal of the depletion mechanism is required.</span></p> application/pdf 10.1038/331705a0 en Springer Nature Granulite fades Nd-isotopic homogenization in the Lewisian complex of northwest Scotland article