【作者】 曲少东；

【导师】 刘池阳；

【作者基本信息】 西北大学 ， 矿产普查与勘探， 2013， 博士

【摘要】 梨树断陷位于松辽盆地东南隆起区,为一典型的断坳叠置复合型沉积断陷,大地构造位置处于吉黑中小地块群与华北板块之间的索伦-西拉木伦-长春-延吉构造拼接带上,基底由燕山早期花岗岩、华力西晚期变质岩、前寒武系基底以及华力西期和加里东期花岗岩共同组成。根据梨树断陷断陷期的构造沉积格局,将梨树断陷划分为4个次级构造单元,分别为十屋深洼陷(断洼)、东部斜坡、双龙洼陷(或断洼)、苏家屯洼陷(断洼),在此基础上划出4个二级构造带：桑树台断裂构造(或断陡)带、小宽断裂构造带、秦家屯断裂构造带和皮家断裂构造带。梨树断陷各断裂带不同时期结构、构造特征整体表明,断陷期主要发生在早白垩世,大致可分为火石岭期、沙河子期、营城期和登娄库期-泉头期早期四大阶段；晚白垩世为区域坳陷期,白垩世末期--新生代为盆地后期改造期。梨树断陷断陷期各主要阶段后期改造活动相对较弱；坳陷期整体沉降,广泛接受沉积；之后盆地开始遭受强烈改造。根据平衡剖面恢复、裂变径迹热模拟等方法,结合区域构造特征,早白垩世火石岭期,在地幔汇聚上隆深部作用活跃的构造环境中,地壳浅部裂陷,桑树台大断裂及秦家屯断裂开始强烈伸展断陷,梨树断陷雏形出现。沙河子期,桑树台断裂带中桑树台断裂、金山断裂和苏家屯断裂及其间侧接带均撕裂伸展,小宽断裂带也开始活动,秦家屯断裂带活动较弱。营城期,桑树台断裂带中的苏家屯断裂和桑树台断裂、皮家断裂构造带和小宽断裂构造带均强烈伸展活动,同时苏家屯洼陷开始强烈断陷。登娄库期-泉头期早期,小宽断裂带中小宽断槽段和双龙洼陷段走滑拉张、小宽隆起段走滑挤压、SW8-SW9井区段平行走滑,秦家屯断裂带因走滑挤压褶皱隆升、秦东断裂贯通,皮家断裂带则进一步撕裂。泉头期晚期-嫩江期,区域坳陷,梨树断陷被巨厚的泉头组上部-嫩江组覆盖。嫩江期末期-明水期,在南东-北西向挤压兼左行走滑构造环境下,小宽断裂带附近强烈褶皱隆起、遭受剥蚀；秦家屯断裂带挤压隆升、秦东断裂向上进一步扩展。古近纪,梨树断陷之东(也是今松辽盆地东缘)裂陷,大致沿郯庐断裂带发育狭长带状展布的依兰-伊通断陷带,在该断陷裂陷沉降和接受沉积过程中,伴有基性火山活动。新生代构造活动和改造对包括梨树断陷在内的今松辽盆地本部改造相对要弱。梨树断陷为早白垩世东北亚裂陷系的组成部分,其形成演化整体受华北板块和西伯利亚板块斜向汇聚及其引起的地幔流体上隆共同导致的区域岩石圈北西-南东向离散应力场控制。早白垩世末期以来,太平洋板块的俯冲作用对东北亚东部构造动力学环境的影响渐趋明显和增强。在晚白垩世,大致以大兴安岭为界,之西的断陷区沉降-沉积作用大为减弱,甚或停止,遭受剥蚀；之东包括梨树断陷在内的松辽盆地进入坳陷期,大范围整体沉降、接受巨厚-较厚沉积。其形成演化的区域动力学环境与古太平洋板块向东亚大陆斜向汇聚及其引起的深部物质运动密切相关。晚白垩世末期以来,大型松辽盆地抬升消亡,周缘地区以遭受剥蚀改造为主,盆地内部有厚度不等、层序不全的新生代不同时代沉积。梨树断陷的箕状断陷结构在宏观上总体控制着油气分布：在平面上油气呈弧形绕深凹陷带状分布,天然气分布在靠近桑树台深凹陷的弧形内环带,如孤家子气田、后五家户气田；在中环带为油气混合区；油田分布在斜坡带的外环带。纵向上油气主要分布于泉二段和泉一段,营城组及沙河子组上部也有少量油气产出。二级构造带对油气的控制明显,目前已发现的油气藏绝大多数位于小宽、秦家屯等二级断裂构造带及其附近。因梨树箕状断陷在断陷期(泉头期前)便已开始规模生烃,位于斜坡受大断裂控制的二级构造带及其附近的局部正向构造发育较早、但定型较晚,处于油气运移的优势方向,具有较长时间捕获油气和对前期已聚集油气进一步调节再运聚的条件。更多还原

【Abstract】 Lishu subbasin is a superposed subbasin composed of fault-subsidence and depression. It is located in the Southeast uplift area of Songliao basin, a part of Solon-Xarmoron-Changchun-Yanji suture zone between medium-small plots of Jihei and North China plate. The basement rock are composed of early Yanshanian granite, late Variscan metamorphic rock, Precambrian basement, Variscan and Caledonian granite. According to the fault depression period deposition pattern of Lishu subbasin, it is divided into four Secondary structural unit:Shiwu sags the eastern slopes Shuanglong sag and Sujiatun sag, on which based,four second-order tectonic belt can be recognised:Sangshutai fault belt, Xiaokuan fault belt, Qinjiatun fault belt and Pijia fault belt.The faulting evolution of Lishu subbasin can be divided into Huoshiling stage, Shahezi stage, Yingcheng stage and Denglouku-early Quantou stage in early Cretaceous.Late Cretaceous was depression period, and late-reformation of basin occured in the end of Cretaceous-Cenozoic. Late-reformation of each major phase were weak in the faulting period; Both subsidence and deposition peaked during depression period; Then the Lishu subbasin was strong reformed in the end of Cretaceous-Cenozoic.In Huoshiling stage, the prototype of Lishu subbasin emerged in the background of mantle converge, crust lacunae, Sangshutai faut and Qinjiatun fault strong stretching. In Shahezi stage, Sangshutai fault zone (include Sangshutai fault, Jinshan fault, Sujiatun fault and Side joint belt) stretched, Xiaokuan fault belt emerged, Qinjiatun fault belt activity was weak; In Yingcheng stage, all the fault were strong stretched; Denglouku stage-Early Quantou stage, Xiaokuan fault trough (D) and Shuanglong sag (A) strike-slip extensional, Xiaokuan uplift (C) strike-slip extrusion, Xiaokuan fault belt B section parallel strike-slip, Qinjiatun fault belt compressed uplift, Pijia fault belt further teared.In the Late Quantou stage-Nenjiang stage, Lishu subbasin was covered by very thick upper Quantou stage-Nenjiang stage; In the end of Nenjiang stage-Mingshui stage, under the SE-NW compression, strong fold uplift and erosion appeared near the Xiaokuan fault belt, Qinjiatun fault belt uplift too; In Paleogene, the east of Lishu subbasin rifted, roughly along the Yilan-Yitong grabens was in the process of sedimentation and deposition, with basic volcanic rock activitis. Tectonic activity and reform in Cenozoci was relative weak in Lishu subbasin and Northern part of Songliao basin.As a part of early Cretaceous basin in Northeastern Asia fault basin system, the evolution of Lishu subbasin was controlled by NW-SE tension stress, resulting from a convergence between North China plate and Siberian plate. Tectonic dynamics environment of East-Asian continent enhanced after the subduction of Pacific plate at the end of the early cretaceous. In late cretaceous, the west aera of Great Khingan deposition reduced, even stopped to suffer erosion, then the east aera of Great Khingan (include Lishu subbasin and Songliao basin) went into depression period and was thickly deposited. From the end of late cretaceous, large-scale Songliao basin began to be lifted and extinct, the sequence of Cenozoic sedimentary was incomplete and the deposition was unequal in basin.The half-graben structure dominated the distribution of the gas and oil in the Lishu subbasin generally. Hydrocarbons is toroidal-fanned located around the deep sag:gas is mostly distributed circularity inner the Sangshutai fault such as Gujiazi, Houwujiahu gas field, while the oil field is distributed outside the ramp region and the mixing area is between the two. The main productive series are Q1, Q2, Yingcheng and the upper Shahezi Formation. Second-order tectonic belt controlled hydrocarbon obviously, most oil and gas traps are found near the second-order tectonic belt. Because the hydrocarbon began to generated in Quantou stage, the second-order tectonic belt, which located in the Oil and gas migration direction turned active relative late, it took a long time to capture oil and gas, and adjust the earlier gathered hydrocarbon.更多还原