关键词: 拉张活动, 渤海盆地, 油气潜力, 拉张量, 早第三纪, 生油岩, 断陷盆地, 拉张史, 渐新世, 下第三系

Abstract: The magnitude of extension of a faulted basin in developing stages can be obtained by means of restoring its palaeostructural cross-section.The extension variation of the depressions in the Bohai basin clearly suggests that the basin was experienced Eocene and Oligocene extension cycles,and the latter involves two subcycles.Chronologically and spacially,the extension was greatly uneven and the source rocks developed in each cycle.For the sedimentary depressions with intensive extension in Eocene and early Oligocene,hydrocarbon was mainly accumulated in Lower Tertiary and basement layers,for those with intensive extension in late Oligocene and slight activities in Neogene,secondary hydrocarbon was trapped mainly in Neogene layers,In accordance with the properties of hydrocarbons in each sedimentary depression,further exploration may greatly widen the prospect of the Bohai basin.