Abstract:

About 80% of discovered oil reserves in the world is sourced from marine source rocks (about 20% from lacustrine facies), and the main control factors of oil reservoir are diversified in different oil-bearing basins. As viewed from global basins, the most important and most common accumulation control factor is oil source, i.e., "source control" is the most important. The major global marine basins are studied through exploring the formation conditions of marine source rocks, and it is discovered that the Persian Gulf Basin, the West Siberia Basin, the Mexico Gulf Basin, the North Sea Basin, the Atlantic Ocean Basin, the East Africa coast Basin, Sichuan Basin, Tarim Basin and Paleo-Tethys Ocean and other basins were all gulfs during the formation period of chief source rocks, i.e., the lands existed in three sides, and a majority of gulfs had only one water channel (a minority had 2-3 water channels) connected to the ocean. The gulf is the most favorable estuary for river. After passing the weathering denuded zone, the river dissolves a large number of minerals to bring the elements including phosphorus, iron and potassium to the gulf as the main nutrients for aquatic organisms such as algae (the nutrients brought by oceanic upwelling is unable to reach the gulf). Because of the seawater replacement between gulf and ocean with blocked communication, the high concentration of nutrient is maintained, and thus can guarantee the long-term reproduction of aquatic organisms such as algae. The small winds and waves in gulfs are favorable to the organic matter preservation, so as to form high-quality source rocks. The relationship between the organisms and rivers in modern oceans and lakes, such as the Bohai Sea, East Sea, South China Sea, Taihu Lake and Dianchi Lake, are studied to further confirm that the main nutrients for aquatic organisms growing are derived from the rivers on land.

Key words: gulf, marine, source rock, basin, river

摘要：

全球已发现的石油储量约80%来自海相烃源岩（约20%来自湖相），在不同的含油盆地，油藏形成的主控因素不同，但纵观全球盆地，最重要、最普通的成藏控制要素是油源，即"源控"最重要。通过对海相烃源岩形成条件的探索，研究了全球主要的海相盆地，发现波斯湾、西西伯利亚、墨西哥湾、北海、大西洋、东非海岸、四川、塔里木和古特提斯洋等盆地的主力烃源岩形成时都是海湾，即三面是陆地，且多数海湾只有1个（少数有2~3个）水道与大洋相连。海湾是河流最有利的入海口，河流经过风化剥蚀区溶解了大量矿物，将磷、铁、钾等元素带入海湾，成为藻类等水生生物的主要营养物质（大洋上升流带来的营养物到达不了海湾）。由于海湾与大洋的海水置换、交流受阻，因此保持了营养物质高浓度，保证了藻类等水生生物长期繁殖。由于海湾风浪较小，有利于有机质保存，因此利于形成优质烃源岩。对渤海、东海、南海、太湖、滇池等现代海洋、湖泊生物与河流关系的研究，也进一步证实了水生生物生长的主要营养物质来源于陆上的河流。

关键词: 海湾, 海相, 烃源岩, 盆地, 河流