Interrogating the provenance of large river systems: multi-proxy in situ analyses in the Millstone Grit, Yorkshire

Establishing the source(s) of sedimentary material is critical to many geological applications, but is complicated by the ability of some minerals to be recycled. To test the relative utility of current proxies for determining a unique provenance, new samples have been collected from the Namurian Millstone Grit Group of Yorkshire, England. Two K-feldspar Pb-206/Pb-204 isotope populations between 12.5 and 15.5 and c. 18.4 are consistent with Archaean-Proterozoic basement and Caledonian granites, respectively. Zircon U-Pb age populations at c. 2700, 2000 - 1000 and 430 Ma reflect a mixture of Archaean basement, overlying Proterozoic sediments and intrusive Caledonian granites, and epsilon Hf values in zircons of all ages indicate crystallization from reworked crust. Garnet major element compositions are relatively rich in Fe and low in Ca, indicative of derivation from a granulitic or charnockitic source. Rutile Cr/Nb ratios indicate that source rocks were dominantly metapelitic, and Zr-in-rutile thermometry records two populations representing lower (c. 650 degrees C) and higher (c. 800 degrees C) metamorphic grade material. Combining these results with published monazite and muscovite data suggests overall derivation from the Greenland Caledonides, with additional contributions from NE Scotland and western Norway, highlighting the power of multi-proxy provenance work, especially in tectonically and geologically complicated regions.