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针对南襄盆地泌阳凹陷程店深水区湖底扇沉积体,进行了岩心、粒度、薄片、重矿等测试资料、砂体结构及地球物理响应的综合分析.结果发现,湖底扇砂体横向与平面结构呈现孤立特征,岩性总体偏细,具粗粒岩性,以块状岩相为主体,显示出砂质碎屑流流态特点,含波状层理和交错层理的层理发育的岩相,2类岩相具分异粒度特征.湖底扇沉积体显示出明显重力流性质,兼具牵引流特点,为复合式搬运机制,其发育受控阵发性洪水作用、盆地幕式旋转掀斜作用及沉积缓倾斜坡因素,是深水背景下洪水成因湖底扇沉积.为追踪其物源,分别从侯庄三角洲与湖底扇区选取砂岩样品,进行碎屑锆石U-Pb定年分析,结果显示:程店湖底扇与侯庄三角洲区砂岩样碎屑锆石测点年龄分布具相似特征,碎屑锆石表面年龄分布显示单峰特征,集中在166～115Ma,该年龄段锆石类型以岩浆成因为绝对主体,含少量变质锆石;同时在247～210Ma、475～412Ma、813～663Ma、3 489～1 692Ma几个主要年龄区间亦具一定数量碎屑锆石分布.综合多方面资料,结合区域地质背景,初步得出如下结论:程店湖底扇砂体与北部侯庄三角洲砂体为同物源沉积组合,源岩主体形成时代为中侏罗世-早白垩,对应燕山构造阶段,主体物源岩系为宽坪-陶湾群构造岩相带中南侧发育的燕山期岩浆岩系,同时,前晋宁期、晋宁期、加里东期及印支期热事件形成的变质岩系或岩浆岩亦可能具不同程度的贡献.
Aiming at the sedimentary body of the sublacustrine fan in the deep water area of Chengdian, Biyang Depression, Nanxiang Basin, the comprehensive analysis of core, grain size, flake, heavy ore and other test data, sand structure and geophysical response was carried out. The plane structure is characterized by isolated features. The lithology is generally fine and coarse-grained. The bulk lithofacies is the main body and shows the flow characteristics of the sandy debris flow. The stratified development with corrugated bedding and alternating bedding Lithofacies and two types of lithofacies.Planet sublacustrine fan shows obvious gravitational flow characteristics, which has the characteristics of traction flow and is a composite handling mechanism, whose development is controlled by the occurrence of paroxysmal flooding. The curtain rotation of the basin The tilt-tilting and sedimentation of gently inclined slope are the sediments of flood-forming sublacustrine fan in the background of deep water.In order to trace its provenance, sandstone samples were selected from the Houzhu Delta and lake bottom sectors to analyze the detrital zircon U-Pb dating, The results show that the ages distribution of zircons in the Chengdian fan and the sandstone-like detritus in the Houzhuang Delta are similar. The age distribution of the detrital zircons shows a single peak, which is concentrated in the range of 166-115 Ma. The zircon type To magmatic origin is absolute With a small amount of metamorphic zircons. At the same time, some detrital zircons are also found in several major age ranges of 247 ~ 210Ma, 475 ~ 412Ma, 813 ~ 663Ma and 3 489 ~ 1 ~ 692Ma.According to the comprehensive data and the combination of regional geology Background, preliminary conclusions are drawn as follows: The Chengdihu sublacustrine fan body and the northern Houzhuang Delta sand body are the sedimentary assemblage of the same source. The source rock body was formed in the Middle Jurassic-Early Cretaceous, corresponding to the Yanshanian structural stage and the main source The rock series are the Yanshanian magmatic rocks developed in the middle and south sides of the Kuanping-Taowan Group structural lithofacies. At the same time, the metamorphic rocks formed in the former Jinning, Jinning, Caledonian and Indosinian thermal events or Magmatic rocks may also have different degrees of contribution.