Geochemistry analysis conducted by the U.S. Naval Research Laboratory of fossil sediment injection structures off the New Zealand coast in February and March reveal no presence of modern day expulsions of methane gas, a potential contributor to global ‘greenhouse effect’ warming.
The main focus of this most recent expedition was to investigate the geological origin of seafloor anomalies discovered during a 2007 marine-life survey on the Chatham Rise.
During the 2007 survey scientists discovered several large seafloor craters, or pockmarks, including a giant 11 kilometers by 6 kilometers pockmark in water depths of about 1,000 meters, considered immense compared with pockmarks observed elsewhere in the world.
Scientists from Germany, New Zealand, and United States used the two-leg voyage aboard the German research vessel, R/V Sonne, to map and investigate giant seabed features and subsurface structures characteristic of large scale gas-rich fluid migration about 500 kilometers east of Christchurch, South Island, New Zealand.
While the gas and related sediment chemistry results demonstrate this system is no longer geochemically active, these very large pockmarks — 11 kilometers by 6 kilometers in diameter and 100 meters deep — are part of a much larger field of many thousands of smaller pockmarks that extends eastward along the Chatham Rise.