Geochemical and isotope composition of pebbles from the Caban Conglomerate Formation and their bearing on the source of Welsh Palaeozoic sedimentary rocks

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Abstract
Major, trace and REE geochemistry, together with Nd isotope determinations, provide new insights into the provenance of seven pebbles of igneous origin from an early Silurian facies of the Caban Conglomerate Formation from central Wales. The geochemical composition of the pebbles supports formation in a subduction related environment on an active continental margin. Biotite whole-rock Rb-Sr systematics constrain the age of a granite pebble to 650±38 Ma. The pebbles provide discrete examples of Avalonian basement which contributed to the isotope composition of sedimentary rocks in the Welsh Basin and one granite pebble provides a rare example from the Welsh Basin of an igneous rock with a Palaeoproterozoic depleted mantle model age.