Nd and Sr isotopes as elastic provenance indicators in the Upper Carboniferous of Britain

Nd-Sr data indicate that two isotopically distinct terrains supplied sedime nt to the Upper Carboniferous basins of Britain. One terrain was relatively depleted in radiogenic Nd, and included large areas of old continental cru st; the other was less depleted in radiogenic Nd and is thought to have inc luded a significant amount of first generation juvenile material that was a dded to the older crust during the early Palaeozoic continental collisions. The isotopic signatures reflect the average composition of the crust from which the Carboniferous sediments were originally derived. In multicyclic, multiorogenic settings such as NW Europe, understanding the geo,geographic distribution patterns of the sediment can only be accurately ascertained by employing a combination of provenance characterizing techniques (isotopes/ palaeocurrents/heavy minerals). Here, combined results indicate that the fi rst terrain lay in Laurentia, whereas the other was a large region borderin g the north side of Gondwana, and including Avalonia and Armorica.