Igneous complexes in the eastern Northern South Yellow Sea Basin and their implications for hydrocarbon systems

Multi-channel seismic reflection data from the eastern Northern South Yellow Sea Basin identify various igneous and related features such as stocks, laccoliths, sills, dikes, volcanic edifices, and hydrothermal vent systems. The stocks are tall, vertical intrusives, characterized by a seismically dead zone with upturned host rocks and uplifted overburden. The laccoliths form broad, low-relief mounds with tapering edges. The sills are imaged as concordant, high-amplitude reflections with a distinct lateral extent. The dikes are characterized by steeply inclined, cross-cutting reflections. The volcanic edifices, observed on the top of the shallow, eroded basement, consist of mounds and peaks, probably representing volcanoes and/or their remnants (or necks). The hydrothermal vent systems consist of a shallow crater-like vent, a vertical conduit that appears as a seismic chimney, and deeper sills.The stocks and the laccoliths can provide hydrocarbon traps similar to those associated with salt diapirs. The dikes, if injected into tilted or deformed strata, can form fault-like traps. The sills may form seals and also enhance the maturation of source rocks by high heat and insulation. The volcanic edifices, if weathered and/or fractured, can provide reservoirs. The hydrothermal vents may form focused conduits for fluid migration.