Paleoceanography And Paleoclimatology
Stott, L., Davy, B. Shao, J. Coffin, R., Pecher, I., Neil, H., Rose, P.
Seafloor pockmarks of varying size occur over an area of 50,000 km2 on the Chatham Rise,
Canterbury Shelf and Inner Bounty Trough, New Zealand.
The pockmarks are concentrated above the flat‐subducted Hikurangi Plateau. Echosounder data identify recurrent episodes of pockmark formation at ~100,000‐year frequency coinciding with Pleistocene glacial terminations. Here we show that there are structural conduits beneath the larger pockmarks through which fluids flowed upward toward the seafloor. Large negative Δ14C excursions are documented in marine sediments deposited next to these sub seafloor conduits and pockmarks at the last glacial termination.
Modern pore waters contain no methane, and there is no negative δ13C excursion at the glacial termination that would be indicative of methane or mantle derived carbon at the time the Δ14C excursion and pockmarks were produced.