The sequestration of trace metals preserved in pyritized burrows

Pyritized burrows from three localities were analysed using LA-ICP-MS to determine their trace element content and assess their ability to sequester trace elements. Pyritic burrows from Hock Cliff (Jurassic), Wren's Nest (Silurian) and Southerham Grey Pit (Cretaceous) have anomalous levels of Se, Cu and Pb and are enriched relative to their host sediments. Sequestration rates were calculated using sedimentation rates from similar depositional environments. Results show that pyritic burrows, mediated by bacterial sulphate reduction, can sequester Se, Cu and Pb up to 3 orders of magnitude greater than the rate of Fe–Mn crusts, which are considered rich sources of trace elements, demonstrating that bioturbated marine sediments are significant sinks of trace elements.