【摘要】 深水沉积是近年来我国海域油气勘探重点之一,利用高精度二维和三维地震剖面的精细解剖,揭示了南海西北陆缘区深水沉积体系类型及其内部构成特征.这些深水地区除堆积正常深海-半深海泥岩外,还发育大量深水重力流沉积,包括块体流沉积、深水峡谷、沉积物波等大型沉积体.研究表明,南海西北陆缘区发育4类陆坡,即进积型、滑塌型、水道化型、宽缓渐变型陆坡.不同陆坡类型具有不同地貌形态,发育不同的沉积体类型.大型块体流沉积主要发育于滑塌型和水道化型陆坡,沉积物波主要发育于宽缓渐变型陆坡下部及深海中央峡谷长昌段的周缘地区.由于南海西北陆缘自晚中新世以来形成向东开口的喇叭形变深的地貌形态,导致在盆地中央形成了独特的与陆坡走向一致的深海峡谷体系——中央峡谷.该峡谷的沉积充填不仅包括来自于西部峡谷头部的浊积水道沉积,还包括来自于北部陆坡的块体流沉积,特别是来自于滑塌型陆坡的块体流沉积.中央峡谷体系构成了西北陆缘区多源汇聚的深水沉积物输送系统,同时也是南海西北陆缘深水区重要的油气储层发育层系.更多还原

【Abstract】 Deepwater reservoir has become one of the major issues in submarine hydrocarbon exploration in China recently. Based on high resolution 2Dand 3Dseismic data,depositional patterns and architectures of deepwater depositional systems are identified on the northwestern continental margins of the South China Sea.Apart from hemipelagic and pelagic mudstones,a number of gravity flow deposits are extensively developed,including large scale mass transport deposits(MTDs),submarine canyons and sediment waves.Four slope types are identified,including progradational type,slumping type,channelized type, wide and gentle type slopes.Each slope type has different morphological features and depositional architectures.Giant MTDs occur on the slumping and channelized slopes,whereas the sediment waves are only developed on the lower part of wide and gentle slope and the two sides of the Changchang segment of the Central Canyon.Due to special morphological features with an eastward flared shape and increasing water depth in the deepwater area since the Late Miocene,the unique Central Canyon with a trend paralleling to shelf break of northern margins is formed along the axial deepest water-depth line.The fillings in the Central Canyon are composed by not only turbidity channels from the head segment of the canyon in the west,but also the MTDs from the continental slope in the north,particularly from the slumping and channelized slopes.The Central Canyon system could be considered as multiple-sources to sink system for sediment transportation,and also a system containing important reservoirs in the deepwater area on the northwestern continental margin of the South China Sea.更多还原