Since 1992, extensive oil seeps have been discovered in Cretaceous sediment and Paleogene basalt onshore central West Greenland. Offshore, the basalts are buried under younger sediments. Interpretation of seismic data offshore has shown the presence of a closed structure at top basalt level. Within the sediments above the closed structure can be seen bright reflections that have strong AVO (amplitude variation with offset) anomalies. These features may indicate the presence of hydrocarbons that have migrated through the basalts from deeper source rocks and been trapped in the sediments above the basalts.