The Leg 104 organic geochemistry program consisted of monitoring (a) hydrocarbon gases, (b) organic and inorganioc carbon, and (c) parameters resulting from Rock-Eval pyrolysis at three sites on the Voring Plateau. In a regional sense there is an inverse correlation between amounts of hydrocarbon gas and organic carbon. For example, a significant concentrations of methane are present only at Site 644 in the inner part of the plateau where organic carbon contents are always less than 1%; in contrast, at Site 642 on the outer plateau, methane concentrations are very low (ppm range) whereas amounts of organic carbon approach 2%. Only at Site 644 are the environmental conditions such that methanogenesis is an active diagenetic process. Because of the importance of routine gas analyses to the Ocean Drilling Program (ODP), a procedure was devised to improve the use of Vacutainers for collection of gas samples. Comparison of methods for determining organic carbon showed that at sites 643 and 644 Rock-Eval TOC could be used as a measure of organic carbon, but not at Site 642. Although no liquid or solid hydrocarbons were encountered at any of the sites, a catalog of potential organic geochemical contaminants was developed in anticipation of such a discovery. -from Authors
