黄河口凹陷古近纪构造坡折带对沉积体系的控制

Constraints by Tectonic Slope-break Zones on the Depositional Systems in Eogene in the Sag of the Yellow River Estuary

坡折带类型、分布对沉积体系具有明显控制作用。通过对黄河口凹陷古近系层序构成样式和沉积充填研究,结果表明:①在盆地幕式断陷活动和同沉积断裂差异活动等构造作用下,形成了断裂坡折和挠曲坡折2种类型的构造坡折带。断裂坡折可以进一步分为断阶坡折、帚状坡折和断裂转换带坡折,不同类型构造坡折带对沉积体系具有明显控制作用。②断阶坡折控制了陡坡带扇三角洲、缓坡带辫状河三角洲沉积体系的形成和分布;帚状坡折控制了沉积体系入湖方向和沉积厚度;断裂调节带控制了辫状河三角洲、湖底扇沉积体系的形成和分布;挠曲坡折控制了辫状河三角洲沉积体系的分布。③构造坡折控制不同类型的圈闭组合,断阶坡折带发育断块型圈闭、岩性上顷尖灭圈闭;帚状坡折带发育掀斜断块圈闭;断裂转换带发育岩性上倾尖灭圈闭、断鼻-岩性圈闭;挠曲坡折带发育地层超覆圈闭。不同类型坡折带对沉积体系的控制为下一步中深层油气勘探指明方向。

The type and distribute of the slope-break zones control the deposifional systems. Comprehensive analyses on the Paleogene sequence compositional types and sedimentary filling patterns. The research indicate： ① The affected by episodic rifting of the basin and differential subsidence of contemporaneous faults, two different structural slope-break types, including fault slope-break and flexure slope-break, fault slope-break include faultterrace slope-break, ＂ brush＂ slope-break and structurally regulated zone. ② The fault-terrace slope-break controlled the formation and distribution of fan delta sedimentary system in steep slopes and belt braided river delta sedimentary system in gentle slopes,＂ brush＂ slope-break control direction of lake and sedimentary thickness. structurally regulated zone controlled the sedimentary system of braided river delta and sublacustrine fan, flexure slope break controlled the braided river delta sedimentary system. ③ The tectonic slope-break zones controlled different types of trap combination. The fault-terrace slope-break controlled the fault flock trap, lithological pinchot trap ;structurally regulated zone controlled lithological pinchot trap, fault-nose trap and lithological trap; flexure slope break controlled stratigraphic overlap trap. Different tectonic slope-break with the development of different types of traps combination direction for the next step in deep oil and gas exploration.