Stratigraphic evolution of provenance characteristics in Westphalian sandstones of the Yorkshire Coalfield

A combined study of heavy minerals and palaeocurrents shows that three main fluvial systems transported sediment to the Pennine Basin during Namurian and Westphalian times. The first, which brought a garnet-rich monazitic hea vy mineral suite from the north, peaked in the Namurian and diminished thro ugh the Langsettian. The second flowed from the west, bringing heavy minera l suites with low garnet, low monazite and variable amounts of chrome spine l. It started in the late Namurian, replaced the first system in the Langse ttian, and dominated thereafter until it was itself replaced in the late Du ckmantian by the third system. This brought a garnetiferous heavy mineral s uite with both monazite and chrome spinel from the E or SE and continued to the top of the preserved sequence, in the late Bolsovian. The first source land lay to the north, perhaps between Laurentia and Baltica, and included high grade metasediments or charnockites and granites. The second sourcelan d lay to the west and included mature, pre-existing elastic sediments of De vonian and possibly Lower Palaeozoic age. Ultramafic rocks such as ophiolit es, possibly associated with Lower Palaeozoic ocean closure, were periodica lly exposed there. The third sourceland lay to the south, probably within t he uplifting Variscan orogenic belt. It included low to moderate grade meta sediments, high-grade gneisses, granites and ultramafic rocks.