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障壁砂坝(障壁岛)不仅是重要的人类生活居住地,还是重要的油气聚集单元。川中上三叠统由滨岸向海方向,障壁砂坝与沼泽、潮坪、泻湖和浅海陆棚相伴生,滨岸局部地区发育有小型三角洲。纵向上,由下至上,障壁砂坝依次与浅海陆棚相、潮汐沟道相、沼泽相和泻湖相等沉积相构成一个完整的沉积旋回。障壁砂坝的形成与海平面稳定上升、小的地形坡降、地形坡折带发育和稳定的砂质物源供给有关。海平面稳定上升,波浪对沉积物进行改造,并在潮下带地形坡折带附近形成长条状的砂体。小的地形坡降有利于波浪和潮汐能量逐渐减弱,砂质沉积物在波折带附近逐渐堆积。随着海平面的持续上升,稳定的砂质物源供给保证障壁砂坝能够持续生长,不被海水淹没。
Barrier Sand Barrier (Barrier Island) is not only an important place where human beings live, but also an important hydrocarbon accumulation unit. The Upper Triassic in the middle and upper Triassic are accompanied by the coastline to the sea and the barrier sand bar is associated with swamps, tidal flats, lagoons and shallow sea shelters. Some small deltas develop in some areas along the coast. Longitudinally, from the bottom to the top, the barrier sand bar forms a complete sedimentary cycle with the facies of the shallow sea shelf, tidal channel facies, swamp facies and lagoons. The formation of barrier sand bar is related to the steady rise of sea level, the small terrain slope, the development of relief slope belt and the stable supply of sandy source. The sea level rises steadily, the waves transform the sediments, and strip-shaped sand bodies form near the subsidence slope relief belt. The small gradient of the terrain is conducive to the gradual decrease of the wave and tidal energy, and the accumulation of sandy sediments near the wave break zone. As the sea level continues to rise, a steady supply of sandy sources will ensure that barrier barges will continue to grow without being inundated by seawater.