Detrital zircon U-Pb ages and source of the late Palaeocene Thanet Formation,Kent, SE England

The sources of the Paleocene London Basin marine to fluviodeltaic sandstones are currently unclear. High analysis number detrital zircon U-Pb age investigation of an early-mid Thanetian marine sand from East Kent, reveals a large spread of zircon age peaks indicative of a range of primary sources. In particular, a strong Ediacaran age peak is associated with the Cadomian Orogeny, while secondary peaks represent the Caledonian and various Mesoproterozoic to Archean orogenies. The near absence of grains indicative of the Variscan orogeny refutes a southerly or southwesterly source from Cornubia or Armorica, while the strong Cadomian peak points to Avalonian origin for a major component of the material. Furthermore, the relatively well expressed Mesoproterozoic to Archean age components most likely require significant additional Laurentian input. Comparison to published data shows that both Devonian Old Red Sandstone and northwesterly (Avalonia-Laurentia) derived Namurian-Westphalian Pennine Basin sandstones show strong similarities to the Thanetian sand. This pattern is consistent with derivation of Thanetian material via a SE draining proto-Thames River system that was initiated in the Paleocene due to uplift of western and northwestern Britain. This river system would have incised and eroded cover sandstones and potentially also Avalonian basement of mid to north Wales and England. However, the possibility of a contribution of Laurentian grains directly from the north via longshore drift cannot be excluded by the data, and the extent to which the sediment source signatures of Paleogene sands of the London Basin are variable both geographically and over time remains unclear.