Origin and accumulation of carbon dioxide in the Huanghua depression, Bohai Bay Basin, China

Geochemistry, origin and accumulation of natural gases in the deepwater area of the Qiongdongnan Basin, South China Sea

“…The CO 2 from both the SS22-1and SS17-2 fields are low in content (0.06e0.70% by volume) and characterized by d 13 C CO2 values ranging from À20.7‰ to À8.5‰, indicating a predominant organic origin with a minor inorganic contribution. Three of four gas samples from the BD19-2 gas pool, however, have CO 2 contents of 18.72e87.52% and are characterized by more positive d 13 C CO2 values ranging from À6.9‰ to À4.3‰, and the R/Ra ratios for helium associated with these CO 2 gases range from 2.66 to 6.25 (Table 1), similar to those of mantle-and magmatic-derived CO 2 gases in eastern China basins (Dai et al, 1996;Zhang et al, 2008). Since these CO 2 gases are located in deeper reservoirs that are connected with deeply buried basement faults, they are interpreted to be of mantle origin, migrating into the reservoirs that are cut through by No.2 Fault.…”

Normal faults and thrusts reactivated by deep fluids: The 6 April 2009 Mw 6.3 L'Aquila earthquake, central Italy

“…The fluid involvement in fault systems characterized by a normal stress regime like that recognized in the L'Aquila region may differ from that in strike‐slip regimes, e.g., the Bohai Bay Basin system (China). Here, mantle‐derived fluids migrate along subvertical faults that cross the basement, and, in particular, at the intersection of faults, where fluid pressure is low because of the continuous gas release [ Zhang et al , 2008].…”

Noble gas isotopic constraints on the origin and evolution of the Jinchuan Ni–Cu–(PGE) sulfide ore-bearing ultramafic intrusion, Western China

“…The first fraction of volatiles released at 200°C from the sample was discarded to get rid of possible contaminants on grain surface and exposed micro-fractures. This method can successfully eliminate noble gases of atmosphere-origin that could be absorbed on mineral surfaces and micro-fractures (Zhang et al, 2004Ye et al, 2007;Zhang et al, 2008). The high-temperature fractions of noble gases released from the sample after a 30-minute sequential heating (200-400°C, 400-700°C, 700-1000°C and 1000-1300°C) were used for analysis.…”