황해 남동부 대륙붕 지대에서 분출되는 탄화수소가스의 지구물리적, 지화학적 연구

Abstract

In the southeastern Yellow Sea, hydrocarbon gases have been actively seeping through a large number of plumes from the topmost pre-Holocene sedimentary layer at least since 1987. The gas seepage often appears to be catastrophic so much as to form craters and diapirs, although pockmarks are rare due to the distribution of mobile palimpsest sands. In core sediments and core-top seawater, the gases are characterized by a large abundance of ethane (C2) and a large difference (19.7‰ PDB, on average) between δ13C1 (-55.2 to –53.6‰ PDB) and δ13C2 (-36.8 to -32.5‰). The gases are regarded to be generated with smaller amount of methane (C1) by thermal cracking of labile source materials at depth, after which they undergo selective but less biodegradation before reaching the seafloor during rapid migration.