The Dongsha fault- uplifted massif (for convenience . Dongsha massif from here on) is located in the northern continental shelf-slope of the South China Sea, where the water depth is 100-400m. The massif is considered...The Dongsha fault- uplifted massif (for convenience . Dongsha massif from here on) is located in the northern continental shelf-slope of the South China Sea, where the water depth is 100-400m. The massif is considered to be a part of the large-scale fault-uplifted zone directed NE and separating the Pearl River Mouth Basin into northern and southern graben areas. The sedimentary cover of the Pearl River Mouth Graben consists mainly of a 7000-10000m thick Tertiary system. A large-scale uplift occurred in the Dongsha fault-uplifted zone during Paleocene-Eocene when the lower structural layer (lower Tertiary) existed only in the small depressions of the fault-uplifted zone. The formation and evolution of the Dongsha fault-uplifted zone could be divided into: 1) the basement formation stage (J2-K1); 2) the slowly uplifted stage (K2-E22); 3) the weathering and erosion stage (E23-E31); 4) the integrated subsidence stage (E32-N12) and 5) the last uplifted stage (N13-Q). The formation of the oil and gas pools展开更多
The gravity and magnetic survey lines of about 13,500 km were carried out in the centraland northern parts of the South China Sea from 1977 to 1978. The results obtained showthat the Bouguer gravity and magnetic anoma...The gravity and magnetic survey lines of about 13,500 km were carried out in the centraland northern parts of the South China Sea from 1977 to 1978. The results obtained showthat the Bouguer gravity and magnetic anomalies have a tendency to increase gradually theirvalues from the northern continental shelf, through the slope, to the central abyssal basin of theSouth China Sea. The change in free-air gravity anomaly values coincides to a certain degreewith the undulation of the sea-bottom topography. The primary factor determining regionalvariation of the Bouguer gravity anomayl values is the Moho depth. The main factor deter-mining the magnetic anomly values is the nature of the basement rock. The high magnetieand Bouguer gravity anomaly values observed in some fault basin areas are inferred to becaused by draping the basic and ultrabasic magma extruding along the faults on the basementof the metamorphic rock,or by intrusion of the same magma into the basement.展开更多
文摘The Dongsha fault- uplifted massif (for convenience . Dongsha massif from here on) is located in the northern continental shelf-slope of the South China Sea, where the water depth is 100-400m. The massif is considered to be a part of the large-scale fault-uplifted zone directed NE and separating the Pearl River Mouth Basin into northern and southern graben areas. The sedimentary cover of the Pearl River Mouth Graben consists mainly of a 7000-10000m thick Tertiary system. A large-scale uplift occurred in the Dongsha fault-uplifted zone during Paleocene-Eocene when the lower structural layer (lower Tertiary) existed only in the small depressions of the fault-uplifted zone. The formation and evolution of the Dongsha fault-uplifted zone could be divided into: 1) the basement formation stage (J2-K1); 2) the slowly uplifted stage (K2-E22); 3) the weathering and erosion stage (E23-E31); 4) the integrated subsidence stage (E32-N12) and 5) the last uplifted stage (N13-Q). The formation of the oil and gas pools
文摘The gravity and magnetic survey lines of about 13,500 km were carried out in the centraland northern parts of the South China Sea from 1977 to 1978. The results obtained showthat the Bouguer gravity and magnetic anomalies have a tendency to increase gradually theirvalues from the northern continental shelf, through the slope, to the central abyssal basin of theSouth China Sea. The change in free-air gravity anomaly values coincides to a certain degreewith the undulation of the sea-bottom topography. The primary factor determining regionalvariation of the Bouguer gravity anomayl values is the Moho depth. The main factor deter-mining the magnetic anomly values is the nature of the basement rock. The high magnetieand Bouguer gravity anomaly values observed in some fault basin areas are inferred to becaused by draping the basic and ultrabasic magma extruding along the faults on the basementof the metamorphic rock,or by intrusion of the same magma into the basement.
