【作者】 梁西文；

【导师】 郑荣才；

【作者基本信息】 成都理工大学 ， 矿物学、岩石学、矿床学， 2008， 博士

【摘要】 论文运用板块构造理论、沉积学理论、层序地层学的理论和方法,贯彻“构造控盆、盆控相”的研究思路,系统开展了中扬子区沉积体系、层序岩相古地理、盆地类型、层序充填,盆山耦合关系研究,以及中新生代陆相盆地与下伏海相盆地的叠加、改造、并列的关系研究,分析海相油气保存条件单元,剖析晚期构造运动、层序充填对海相盆地成藏的建设性意义和破坏性作用,指出海相盆地有利勘探远景区。1、中新生代沉积体系研究在5条露头剖面实测的基础上,结合钻井、地震资料综合分析,划分出四种沉积体系类型即:冲积扇、河流、三角洲、湖泊沉积体系,建立了可反映沉积体系基本特征和空间展布几何形态的沉积相类型或单元。根据晚三叠世—新近纪沉积演化特点,划分出五种沉积模式:①前陆盆地的扇三角洲—湖底扇组合的二级扇沉积模式;②前陆盆地的冲积扇—三角洲—湖底扇组合的三级扇沉积模式;③断陷型湖盆的冲积扇—河流—三角洲—湖泊沉积模式;④断陷型湖盆冲积扇—扇三角洲—湖泊沉积模式;⑤坳陷型湖盆的河流—三角洲—湖泊沉积模式。2、层序划分和特征研究根据地表露头观察到的不整合面、侵蚀面和沉积间断面,结合古生物、沉积相资料及地震反射波组的上超、下超、削截,明确不整合面时空展布范围,取得如下认识:①上三叠统—新近系共划分3个一级层序、10个二级层序,21个三级层序。②上三叠统—新近系识别出8种层序界面识别标志:古风化壳、区域不整合界面、石英质砾石层、侵蚀及冲刷、较长时间的暴露及钙结壳、相序不连续及相转换面、地震剖面上反射终止现象,如上超、削截等接触关系、古气候转换面。③层序界面形成与构造运动密切相关,根据导致层序界面形成的构造运动特点,层序界面分为五种成因类型:抬升隆起侵蚀不整合、同构造期渐进不整合、造山隆升剥蚀不整合、水下侵蚀切割层序不整合、应力场的转换及古气候变化造成的不整合。④分析了中新生代层序发育控制因素,认为层序发育是构造运动、湖平面升降、沉积作用和气侯四大因素共同作用的结果。3、系统构造—层序岩相古地理编图与研究选择10个二级层序体系域(即盆地扩张体系域和盆地收缩体系域),作为中新生代岩相古地理编图单元,按照“构造控盆、盆控相”思想,首次系统的编制了更具科学性、等时性、成因连续性和勘探实用性的全区构造—层序岩相古地理图。研究区晚三叠世—侏罗纪岩相古地理明显受盆地形成及发展演化制约,现有的资料表明,盆地演化可分为四个阶段,即盆地形成阶段、盆地早期发展阶段、盆地晚期发展阶段、盆地萎缩阶段,不同阶段盆地充填系列特点不同。①盆地形成阶段—河流沉积充填为主,该阶段对应于晚三叠世(即Ts2、Ts3期),盆地处于初始发育阶段,研究区多为互不连通的小型盆地,沉积范围较小,盆地充填系列以河流相、沼泽相为主,湖泊沉积不发育。②盆地早期发展阶段—湖泊、三角洲、河流沉积充填,此阶段对应于早侏罗世(即Ts4期)。印支运动Ⅱ幕之后,研究区总体处于相对强烈坳陷时期,陆源区退缩,陆源碎屑供应相对匮乏,沉积区域明显扩大,出现了较多的湖泊相沉积。③盆地晚期发展阶段—河流相砂泥岩充填为主,此阶段对应于中侏罗世(即Ts5期)。燕山运动Ⅰ幕之后,研究区总体仍处于相对强烈坳陷时期,沉积范围较大,陆源碎屑供应充足,沉积厚度巨大。④盆地萎缩阶段—河流充填为主,此阶段对应于晚侏罗世(即Ts6期)。燕山运动Ⅱ幕之后,荆当盆地以及鄂东一带为隆起区,局部开始裂陷;鄂西渝东一带为坳陷区,接受沉积区域明显缩小,沉积基底强烈坳陷,沉积厚度巨大,以河流相砂泥岩充填为主,以上四个盆地演化阶段与晚三叠世至早白垩世(研究区大部分缺失)盆山耦合反映的前陆盆地三次幕式演化阶段具有较强的对应关系。研究区白垩纪—新近纪层序岩相古地理演化表现为:燕山运动Ⅲ幕、Ⅳ幕,对应构造层序Ts7、Ts8沉积时期,盆地以北西向断陷作用为主,处于亚热带干旱的古气候条件,湖泊类型为宽而浅的氧化型湖泊,沉积物类型以氧化色调为主,暗色泥岩不发育,缺乏生烃能力;物源为多源(以西部为主)、近源碎屑物质,由盆缘至中心构成冲积扇—河流—三角洲—氧化型滨浅湖的沉积体系。几条北西向展布断裂前缘为几个大的沉降带,缺乏统一的沉积中心。燕山运动Ⅴ幕,对应构造层序Ts9、Ts10沉积时期,发育多期断拗旋回:旋回早期以断陷作用为主,中晚期以拗陷作用为主,盆地整体上处于中亚热带半干旱干—湿交替的气候条件,湖泊类型为浅水—(半)深水的弱氧化—还原性湖泊,发育浅湖—(半)深湖沉积,暗色泥岩发育,是盆地两套主力烃源岩发育的时期;整体上以北部物源为主,也存在东北部物源。断陷期,当物源与断裂方向垂直时,受断裂的控制而发育水下扇—扇三角洲—湖泊沉积;坳陷期,发育河流—三角洲—湖泊沉积。同时,由于古地形和物源的作用,导致沉积相带在南、北两侧呈不对称分布,砂岩呈现北厚南薄的分布格局,盆地南部为统一的沉积中心。该期是江汉盆地两套主要勘探目的层—新沟咀组下段和潜江组发育的时期。喜山期,对应构造层序Ts11沉积时期,渐新世末期的喜山运动,盆地整体抬升遭受剥蚀,结束裂陷盆地发育史。新近系中新统,在区域重力均衡作用下,盆地进入缓慢的拗陷沉降期,主要的沉降中心位于潜北洼陷。主要发育河流相沉积。4、中新生代沉积演化(盆山耦合)与物质响应关系研究论文通过晚三叠世-新近纪的层序地层格架、层序岩相古地理分析、沉积物组合、岩石学特征、沉降史分析来揭示盆地构造作用过程、盆缘造山带构造作用过程及盆地沉积物质充填过程。首次系统的揭示了自印支期以来,中扬子区盆山演化过程;①早三叠世(含晚二叠世)至中三叠世记录了扬子北缘由大陆边缘盆地转变为残留海盆地,反映印支期华北(秦岭)板块与扬子板块之间软碰撞,研究区碰撞未造山的过程;②晚三叠世至早白垩世(研究区部分缺失)记录前陆(磨拉石)盆地的三次幕式演化阶段,反映华北(秦岭)板块与扬子板块之间早燕山期呈斜向陆、陆碰撞,前展逆冲推隆造山作用幕(脉动)式过程;研究表明造山带和前陆盆地具有很好的耦合关系,主要表现在造山带的隆升过程和盆地的沉降历史、地层的剥蚀和充填的沉积物、地层的不整合分布与造山带的迁移规律、构造沉降速率与地层堆积方式等方面均具有对应关系。概括起来,前陆盆地沉积充填特征是造山带的形成演化和前陆盆地沉降的结果。③晚白垩世至古近纪前陆盆地改造与裂陷盆地发育阶段,构造背景发生重大变化,受到郯-庐断裂强烈活动、中国东部软流圈物质上涌以及推隆造山造成加厚的岩石圈因重力失稳等因素,形成快速均衡隆升、走滑块断隆陷构造以及一系列反转伸展断陷盆地。5、中扬子区中新生代盆地与下伏海相盆地叠加、改造、并列的关系,为我们深入认识海相油气成藏规律,分析海相盆地油气勘探前景,优选海相油气勘探区提供了依据,这一分析思路遵循:“构造控盆、盆控相”的思想,同时把层序充填的动态分析过程应用于油气勘探保存条件与勘探前景分析中。中新生代盆地与古生代盆地的叠覆关系划分为5类:①连续型覆盖;②早期暴露型覆盖;③晚期暴露型覆盖;④间断暴露型覆盖;⑤持续暴露型覆盖。根据叠覆关系,划分出四种含油气保存条件单元,即持续型、重建型(沉积重建型)、重叠型、剥蚀残余型。鄂西渝东区与秭归盆地区划分为持续型含油气保存条件单元,江汉平原南部区划分为持续型—重建型含油气保存条件单元,大洪山弧形构造带划分为重叠型含油气保存条件单元,江汉平原南部与大洪山弧形构造带之间的区域为持续型—剥蚀残留型含油气保存条件单元、湘鄂西区为剥蚀残留型含油气保存叠加单元。6、通过深入研究认为,在中扬子地区现今构造面貌复杂,海相勘探构造圈闭与成油气期不是十分配套的条件下,主要含油气领域应当是大面积稳定地块圈闭构造,古隆起周缘区,逆冲推复构造带的逆掩原地体,以及上、下构造极不协调形成的潜伏构造圈闭等。优选鄂西渝东褶皱带;秭归盆地区;古隆起周缘区,包括宜都—鹤峰复背斜的北部、当阳复向斜的南部;江汉盆地南部作为前四个层次的海相油气勘探远景区。更多还原

【Abstract】 Based on the theories and methods of plate tectonic theory and sedimentology,following the research idea of "the structure controlling the basin" and "the basin controlling the facies", this paper studies systematically the basin types,sequence filling,basin-mountain coupling relations,and the superimposition,reform,and juxtaposition relations between Meso-Cenozoic continental basins and underlying marine facies basins,analyzes the preservation condition units of marine facies hydrocarbon,dissects the constructive meaning and disruptive effect of later structural movement and sequence filling on the reservoir formation in marine facies basins,and points out the favorable prospect area in marine facies basins,The detailed study results are as follows..1.A systematic study of Meso-Cenozoic depositional systemsOn the basis of 5 measured outcrop profiles,combined with the comprehensive analysis of drilling and seismic data,four depositional systems,i.e.,the alluvial fan,fluvial,Delta,and lacustrine depositional systems are classified,the facies types or units which can reflect the essential characteristics and spatial distribution geometry of depositional systems are established.According to the depositional evolution features of Late Triassic-Neogene,it can be divided into five depositional modes.①the secondary fan depositional mode with the combination of fan delta and sublacustrine fan in the foreland basin;②the tertiary fan depositional mode with the combination of alluvial fan,delta and sublacustrine fan;③the alluvial fan-fluvial-lacustrine depositional mode of rifted lake basin;④the alluvial fanfan deltas - lacustrine depositional mode;⑤and the fluvial-delta-lacustrine depositional mode of depressed lake basin.2.Sequence division and their characteristicsAccording to the unconformities,erosion surfaces,and hiatus surfaces observed on surface outcrops,combined with the palaeontologic and depositional faices data,as well as the phenomena of onlap,downlap and truncation in seismic reflection wave groups,the space-time distribution range of unconformities is clarified as shown in the following①The Upper Triassic-Neogene of the middle Yangtze area can be divided into 3 primary sequences,10 secondary sequences,and 21 tertiary sequences.②The formation of sequence boundaries is closely related to the tectonic movement.According to the features of tectonic movement resulting in the formation of sequence boundaries,the sequence boundaries can be classified into the following genetic types:the uplift erosion unconformity,the syntectonic progressive unconformity,the orogenic uplift erosion unconformity,the subaqueous corrosion unconformity,and the stress field transformation or palaeoclimate alternation-incurred unconformity.③Ten identification marks of sequence boundary are identified in the Upper Triassic-Neogene of the work area:the paleocrust of weathering,the regional unconformity boundary,the cherty gravel bed,the erosion and scouring,the long-time exposure and kalkkruste,the discontinuous facies sequence or facies transform interface,and the ending phenomena on seismic profiles,such as the contact relations,e.g.,onlap and truncation,and palaeoclimate transform interface.④The factors controlling over the development of Meso-Cenozoic sequences in middle Yangtze area are analyzed.It is considered that the sequence development is the result of the synergic effect of four factors,i.e.,tectonic movement,lake level rise,deposition and climate3.Mapping and study of the lithofacies palaeogeography of structures and sequences for the systemTen system tracts(basin extension system tract and basin shrinkage system tract)of secondary sequences are selected to serve as the compilation units for the mapping of Meso-Cenozoic lithofacies palaeogeography.According to the idea of "the structure controlling the basin" and "the basin controlling the facies",the lithofacies paleographic map of structures and sequences of the whole area,which is more scientific,more isochronous, more continuous in origin,and more practical in exploration,is compiled for the first time(Innovation point).In the study area,the lithofacies paleography of the Late Triassic-Jurassic is associated with development and evolution of the basin.Available data indicate that the basin evolution can be divided into 4 stages,namely origination,early development,late development and abortion stages,which have different filling features from each other.①During the basin origination,fluvial filling was dominant.This stage is considered to correspond to Late Triassic when the Sequences TS2 and TS3 were deposited.During this stage,the basin consists of small isolated basins,which were small,fluvial and swamp-dominated,with undeveloped lacustrine deposits.②Early basin development stage—when lacustrine, deltaic and fluvial filling were deposited.It corresponds to the period when the Sequence TS4 was deposited.Since the episodeⅡof the Indosinian Movement,the Middle Yangtze Plate depressed entirely,with significantly widened sedimentary extent.The aborted provenance supplied relatively absent detrital material of terrigenous origin,resulting in much lacustrine deposits due to differentiation in paleogeography.③During the late basin development, fluvial sandstone-mudstone filling was dominant,which corresponds to the period when the Sequence TS5 was deposited.Since the EpisodeⅠof the Yansanian Movement,the Middle Yangtze Area has been in an intensive depression stage,with abundant detrital material of terrigenous origin supplied and deposited with great thicknesses.④During the basin abortion, fluvial filling was dominant.This stage corresponds to the period when the Sequence TS6 was deposited.During this stage,the Jinmen-Dangyang and Qianjiang-Eastern Hubei trend was in an uplift area,except for the Western Hubei- Eastern Chongqin-Zhigui Basin trend in a depression area.During this stage,the deposition area is significantly reduced,with the basement intensively depressed,and very thick deposits dominated by fluvial sandstone-mudstones.In the study area,evolution of the lithofacies paleography of the Cretaceous-Neogene sequence is characterized by NW-trending fault-depression in the basin during the episodesⅢandⅣof the Yanshanian Movement when the Sequences Ts7 and Ts8 were deposited, as well as by the arid paleoclimate of the subtropical zone,with wide,shallow,oxidized lakes, where deposits in oxidized colors were dominant,with undeveloped dark mudstones,less potential for hydrocarbon generation.The deposits consist of polyenic(mostly in the west) and proximal detrital material,including alluvial-fluvial-deltaic-oxidized shore neritic deposits from margin to center of the basin.Several NW-trending fault fronts represent great subsidence zones in absence of a common depocentre.During the episodeⅤof the Yanshan Movement when the Sequences Ts9 and Ts10 were deposited,multi-period fault-depression cycles occurred,which can be divided into the early cycle dominated by fault depression,and mid- late cycle was dominated by depression, when the entire basin was in hemi-arid,arid alternative with humid climate in the mid subtropical zone,with neritic-(hemi)abyssal deposits,including well-developed dark mudstones.This stage represents a main period when the two main source rocks were developed.Himalayan when the Sequence Ts11 was deposited.During the Himalayan Movement of the latest Oligocene,the basin was entirely uplifted and eroded,representing the end of the rift-depression basin development.During the Miocene of the Neogene,the basin was in a slow depression and subsidence period,with the subsidence center in the North Qianjiang sag, where fluvial deposits were deposited. 4.Study of the basin - mountain coupling and material response relations of Meso-CenozoicBased on the analyses of sequence stratigraphy framework,sequence lithofacies palaeogeography,sediment combination,and subsidence history of Late Triassic Late Triassic -Neogene,this paper explains the tectonic action process of basin,the tectonic action process of the orogenic belt of basinal margin,and the filling process of basinal sediments. and reveals the evolutionary process of basins and mountains in the middle Yangtze region since Indo Chinese for the first time;①Early Triassic(including Late Permian)to Middle Triassic recorded the transformation of the northern margin of Yangtze from a continental margin basin to a residual marine basin,reflected the soft collision between North China(Qin Ling)plate and Yangtze plate in Indo-Chinese epoch,and showed the process of collision in the study area without orogenesis;②Late Triassic to Early Cretaceous(partly nonsequential in the study area)recorded the three episodic evolutionary phases in the foreland(Molasse) basin,reflected the oblique land - land collision between North China plate(Qin Ling)and Yangtze plate in Early Yanshanian,and the episodic(pulse)process of orogenesis by advance thrust uplifting;The study indicates that there is a good coupling relation between the orogenic belt and the foreland basin,which is characterized mainly by the coincidence relations in the following points:the uplifting process of the orogenic belt and the subsidence history of the basin,the stratigraphic denudation and the sedimentary fills,the stratigraphic unconformity distribution and the shifting regularity of the orogenic belt,the tectonic subsidence rate and the accumulation style of formations.In summary,the sedimentary filling characteristics of the foreland basin are resulted form the formation and evolution of the orogenic belt and the subsidence of the foreland basin.③In the stage of foreland basin reform and rifted basin development from Late Cretaceous to Paleogene,the structural setting underwent significant changes.Affected by a lot of factors such as the intense activity of Yan-Lu fault,the material upwelling of asthenosphere in eastern China,and the instability of the thrust uplifting-induced thickened lithosphere because of gravity,there formed some rapidly and evenly uplifted and strike-slip uplifted or depressed structures,as well as a series of reversed extension downfaulted basins(Innovation point).5.The relationships of superposition,reform,and juxtaposition between Meso-Cenozoic basins and underlying marine facies basins in middle Yangtze region provides us with foundations for the analysis of the regularities of marine facies reservoir formation,the analysis of oil and gas exploration prospects in marine facies basins,and the optimization of marine facies oil and gas exploration districts.The analysis follows the idea of "the structure controlling the basin" and "the basin controlling the facies",and applies the dynamic analysis process of sequence filling into the analysis of the preservation conditions and exploration prospects for oil and gas exploration The superposition relations for Meso-Cenozoic basins and Palaeozoic basins can be divided into 5 types:①the successive coverage;②the earlier exposed coverage;③the later exposed coverage;④the discontinuously exposed coverage; and⑤the continuously exposed coverage.According to the superposition relations,four oil/gas preservation condition units are classified for Middle Yangtze region,i.e.,the successive type,the reconstruction(sedimentary reconstruction)type,the superposition type, and the post-eroded relic type.The region of Western Hubei and Eastern Chongqing and the region of Zigui Basin belong in the type of successive oil/gas preservation condition unit;The southern part of Jianghan Plain,the successive type - the reconstruction type of oil/gas preservation condition unit;The arc structure belt of Dahongshan Mountain,the superposition type of oil/gas preservation condition unit;The area between the southern part of Jianghan Plain and the arc structure belt of Dahongshan Mountain,the sucessive typepost-eroded relic type of oil/gas preservation condition unit;And the Western Hunan and Hubei,the post-eroded preservation condition type of superposed oil/gas units(Innovation point).6.Through the in depth study,it is considered that in the cases of complex structural features and not fully matched conditions for the marine facies exploration structural traps and oil/gas formation time,the main oil/gas-bearing areas must be the trap structures in the large sized epeirocratic craton,the periphery area of the palaeohigh,the thrusting in-place geologic body in the structural belt of thrusting and overriding,and the buried structural traps formed due to severe inconsistency between upper and lower structures.Four levels of areas are selected as the marine facies oil and gas exploration prospects,i.e.,the folded belt of Western Hubei and Eastern Chongqing,the basinal area of Zigui,the periphery area of the palaeohigh(including the northern part of Yidu-Hefeng anticlinorium,and the southern part of Dangyang synclinorium),and the southern part of Jianghan Basin.更多还原