可容纳空间概念在陆相断陷盆地层序分析中的应用——以渤海湾盆地下第三系为例

以渤海湾盆地下第三系为例,将可容纳空间概念应用于陆相断陷盆地层序成因分析和层序划分。陆相断陷盆地层序、准层序组和准层序的发育过程和基本特征,可分别根据二级、三级和四级幕构造沉降过程中新增可容纳空间与同期沉积物供给体积的对比关系解释,层序边界和体系域分界面的形成条件亦可通过分析可容纳空间变化加以描述和认识。由可容纳空间演变特点分析,引出了一个新概念———可容纳空间转换面,并用于识别层序边界和体系域分界面。     

泌阳断陷陆相层序外部构型研究

摘 要　 泌阳断陷陆相层序外部构型研究包括层序级别的厘定与划分以及界面的类型及其识 别标志。陆相层序构成单元可分为8个级别‚前4级属低频层序‚后4级为高频层序。泌阳 断陷湖盆的3类盆地原型‚分别形成了3套盆地充填序列及其所对应的3个构造层序 （Ⅰ‚ Ⅱ‚Ⅲ）;构造层序Ⅱ为该断陷湖盆的沉积充填主体‚可进一步划分为7个层序组‚其中在层 序组Ⅱ D （即核三段上） 中可识别出3个层序。陆相层序的体系域具四分性：低水位体系域、 水进体系域、高水位体系域及水退体系域;小层序组有4种基本类型：进积小层序组、低位 加积小层序组、退积小层序组和高位加积小层序组。     

可容纳空间转换系统的定量模拟

为探讨盆地两侧可容纳空间和层序叠加模式的非一致性变化,利用SEDPAK二维层序模拟软件,通过考虑控制层序沉积过程的不同参数,对可容纳空间转换系统进行定量模拟并提出新的认识.模拟结果表明,盆地两侧同期层序叠加模式可以分为"同步"和"非同步"两种,同步叠加模式多出现在层序的低位体系域及高位体系域后期,非同步叠加模式多出现在层序的水进体系域及高位体系域初期.多种地质参数的合理组合,盆地两侧同期层序均可形成非同步叠加模式.非同步叠加模式对体系域界面的识别、层序对比具有一定的参考价值.     

陆相断陷盆地的构造层序地层分析

陆相盆地层序地层构型是构造运动、古气候、古湖平面变化与沉积物补给等动力学要素对沉积基准面控制的综合效应。其中,构造运动对盆地层序界面形成与层序内部充填起至关重要的作用。因此,陆相盆地层序地层研究须以构造层序地层为主线,即通过构造对层序形成与演化的控制分析解释层序地层构型,预测其内部充填特征。经研究,断陷盆地构造运动对层序地层的控制主要表现在:(1)断裂活动通过控制基底升降运动直接制约着盆地沉积物堆积的可容纳空间的变化及至层序地层构型;(2)构造转换带或调节带控制盆地主体物源补给方向和沉积体系分布;(3)断裂活动及其塑造的古地貌控制着沉积体系与砂体分布特征。     

断陷湖盆陡坡带陆相层序地层学模式研究①

以泌阳断陷双河-赵凹地区下第三系核三上段陆相层序地层学研究为例,建立了断陷湖盆陡坡带陆相层序地层学模式①陆相层序及其体系域界面模式;②体系域模式;③陆相层序地层模式。其中,陆相层序地层模式包括岩相格架模式及年代框架模式两个内容。研究结果显示,断陷湖盆陡坡带可识别出Ⅰ型和Ⅱ型两类陆相层序;一个完整的Ⅰ型陆相层序从下往上发育LST、TST、HST及RST四个体系域,共五个界面,除顶、底界面归属层序界面之外,其它三个界面皆为体系域界面;而Ⅱ型陆相层序缺失LST。无论何种体系域,其沉积体的几何形状均为楔状体,且各体系域的沉积相横向配置呈现规律性变化。陆相层序地层等时框架模式清晰地显示了研究区下第三系核三上段的沉积充填史及其沉积层序时空展布特征。     

断陷湖盆陡坡带陆相层序地层学模式研究--以泌阳断陷双河-赵凹地区下第三系核三上段为例

以泌阳断陷双河-赵凹地区下第三系核三上段陆相层序地层学研究为例,建立了断陷湖盆陡坡带陆相层序地层学模式:①陆相层序及其体系域界面模式;②体系域模式;③陆相层序地层模式.其中,陆相层序地层模式包括岩相格架模式及年代框架模式两个内容.研究结果显示,断陷湖盆陡坡带可识别出Ⅰ型和Ⅱ型两类陆相层序;一个完整的Ⅰ型陆相层序从下往上发育LST、TST、HST及RST四个体系域,共五个界面,除顶、底界面归属层序界面之外,其它三个界面皆为体系域界面;而Ⅱ型陆相层序缺失LST.无论何种体系域,其沉积体的几何形状均为楔状体,且各体系域的沉积相横向配置呈现规律性变化.陆相层序地层等时框架模式清晰地显示了研究区下第三系核三上段的沉积充填史及其沉积层序时空展布特征.     

鄂尔多斯盆地东北缘煤铀岩系层序地层与煤铀赋存规律研究

运用陆相层序地层理论,采用露头、钻孔和地震剖面相结合的手段,在"岩性-岩相-相序"研究基础上,对鄂尔多斯盆地东北缘中—下侏罗统延安组、直罗组进行了层序地层划分。研究表明,延安组可以划分为5个层序、直罗组4个层序,每个层序由低可容空间体系域和高可容空间体系域组成。根据煤层、铀矿赋存特征,及其在层序地层格架中的位置,指出延安组煤层主要赋存在层序高可容纳空间体系域的三角洲平原泥炭沼泽环境中,直罗组含铀岩系主要发育在直罗组下部辫状河沉积岩段,铀矿赋存在低可容纳空间体系域中。结合地质、地球化学、古生物资料,探讨了古气候、构造对煤、铀矿成矿的制约。     

试论构造因素对泌阳断陷陆相层序形成的影响机制

构造作用是控制泌阳断陷湖盆陆相层序发育的关键性因素，它制约着低频层序（盆地充填序列、构造层序、层序组及层序）的发生、发展与形成。区域性构造运动控制着盆地充填序列及构造层序；盆地边界断裂的脉动性控制着层序组及层序。在陆相断陷湖盆中，盆地基底构造沉降是非线性或间断函数；由盆缘控盆边界断裂向盆地中心，沉降速率逐渐减小，呈“反铰链式”沉降。在从假定湖平面变化呈一正弦函数曲线、物源供给速率中等且匀速的条件下，采用计算机分别模拟了加速沉降和减速沉降两种过程的陆相层序响应特征。研究结果表明，一个构造沉降旋回过程控制着一个陆相层序及其体系域的发育和形成。     

断陷盆地构造作用与层序样式

我国东部大多数中新生代含煤和含油气盆地是陆相断陷盆地，其层序形成和演化主要受控于幕式构造作用。笔者通过典型断陷盆地层序层的研究，根据构造沉降及其可容空间变化特点，提出了拉张型，挤压型，走滑－伸展型和热沉降型四种层序样式，并总结了各种层序中体系域构成特点，概括了多幕裂陷型，断坳转化型和走滑－伸展型三种层序地层格架模式。     

江西信丰县大塘红盆地露头层序地层学及盆地演化初步研究

在1：5万区调基础上，依据陆相纸盆地层序界面的性质及层序体系域的划分原则，对江西省信丰县大塘盆地层序的发育特征进行了初步研究，共识别出3个SB1和1个SB2界面，划分出四个三级层序，并建立了岩石地层格架；每个三级层序由三个体系域（LST、TST、HST）组成，并发育若干个四级旋回；分析了影响层序形成的主控因素；大塘盆地的发展大致从晚白垩世坎潘期开始至马斯特里赫特期末，经历了四个由断陷-盆地扩张-盆地萎缩的党政军化过程；各阶段的构造活动、物源区特征、古气候变化、古生物特征、湖泊性质等经历了各自的发展历程。     

断陷盆地拗陷期河流层序样式及其地貌响应:以渤海湾盆地沙垒田凸起区新近系明化镇组下段为例*

对于断陷盆地拗陷期远离滨岸的河流而言,其层序划分是层序地层学研究的难点。本研究在已有钻测井、岩心及地震资料分析基础上,以渤海湾盆地沙垒田凸起区新近系明化镇组下段(简称“明下段”)作为研究对象,将其划分为1个完整的三级层序、4个四级层序(即SQm1-SQm4)。沉积间断面、宽浅下切谷及复合连片砂体是该地区河流层序界面重要的识别标志。每个四级层序均由低可容空间和高可容空间体系域组成。地震地貌学定量分析表明,低可容空间体系有利于低弯度河流(辫状河、低弯度曲流河)发育,高可容空间体系域有利于中高弯度河流发育。新增可容空间和沉积物供给速率的变化对于河流不同体系域的砂体样式具有重要控制作用。     

Fluvial sequence pattern and its response of geomorphy in depression phase of rift basin: A case study of the Lower Member of Neogene Minghuazhen Formation in Shaleitian Uplift area,Bohai Bay Basin

The sequence classification is a difficulty of sequence stratigraphic study on rivers that are distal to coast area during the depression phase of rift basin. Based on the integrated analysis of logging,cores and seismic data,the case study shows that the Lower Member of Neogene Minghuazhen Formation in the Shaleitian Uplift area in the western Bohai Sea region corresponds to one complete third-order sequence which can be divided into four fourth-order sequences(i.e. SQm1-SQm4). Sedimentary hiatus,wide and shallow incised valley and amalgamated channel sand bodies are the main recognition of sequence boundaries in fluvial sequence stratigraphy of the study area. Each fourth-order sequence comprises low and high accommodation systems tracts. According to seismic sedimentological and quantitative geomorphological analysis,low-sinuosity rivers including braided river and low-sinuosity meandering river are well developed in the low accommodation systems tract,whereas the medium- to high-sinuosity meandering rivers are well preserved in the high accommodation systems tract. The change in the new creation of accommodation and the sediment supply exert a significant control on the stacked pattern within different systems tracts.     

辽河坳陷曙北地区新生代层序地层及沉积体系发育特征

曙北地区是辽河坳陷西部凹陷的一个次级单元,是在太古界和中、晚元古界基底上发育起来的新生代裂谷盆地,新生界自下而上发育的地层为古近系房身泡组、沙河街组、东营组和新近系馆陶组,并覆盖第四系的沉积。通过地震、测井和地质资料的综合研究及时频分析技术的应用,本区新生代裂谷盆地沉积可划分为1个大陆裂谷巨层序、1个大陆裂谷后热沉降超层序和1个同裂谷沉降超层序、4个层序和14个体系域,并存在I型层序和Ⅱ型层序。通过研究提出了断陷湖盆缓坡层序地层模式,揭示了不同的体系域中沉积体系的发育具有的不同特征。在两种不同类型层序的TST和HST之间,常发育大套的页岩,构成主要的生油层和盖层,各体系域的边缘场所构成良好的储层。本区层序地层的划分对于优质储层的寻找和油气富集规律的研究具有重要意义。      

Sequence stratigraphy of coal‐bearing,high‐energy clastic units: The Maitland‐Cessnock‐Greta Coalfield and Cranky Corner Basin

Upper Carboniferous to Lower Permian sedimentary rocks extend along the periphery of the northern Sydney Basin, a sub‐basin of the Sydney‐Gunnedah‐Bowen Basin complex. The basin contains basal basalts and volcanic sediments deposited in a nascent rift zone. This rift zone was created through crustal thinning during trench rollback on the eastern edge of the New England Orogen. Thermal subsidence created accommodation for predominantly marine Dalwood Group sediments. Clastic sedimentation then occurred in the Maitland‐Cessnock‐Greta Coalfield and Cranky Corner Basin during the Early Permian. This occurred on a broad shelf undergoing renewed thermal subsidence on the margin of a rift flank of the Tamworth Belt of the southern New England Orogen. Braidplain fans prograded or aggraded in two depositional sequences. The first sequence commences near the top of the Farley Formation and includes part of the Greta Coal Measures, while the second sequence includes the majority of the Greta Coal Measures and basal Branxton Formation. Thin, areally restricted mires formed during interludes in a high sedimentation regime in the lowstand systems tracts. As base‐level rose, areally extensive mires developed on the transgressive surface of both sequences. A paludal to estuarine facies changed to a shallow‐marine facies as the braidplain was transgressed. The transgressive systems tracts continued to develop with rising relative sea‐level. Renewed uplift in the hinterland resulted in the erosion of part of the transgressive systems tract and all of the highstand systems tract of the lower sequence. In the upper sequence a reduction in relative sea‐level rise saw the development of a deltaic to nearshore shelf highstand systems tract. Extensional dynamics caused a fall in relative base‐level and the development of a sequence boundary in the Branxton Formation. Finally, renewed thermal subsidence created accommodation for the overlying, predominantly marine Maitland Group.     

Origin of the Rift Under the Amazon Basin as a Result of Continental Collision During Pan- African Time

A 1000-km-long positive gravity anomaly occupies the axis of the Amazon Basin and has been taken to indicate the presence of an underlying intracontinental rift. The oldest known sediments in the basin form the Trombetas formation of Late Ordovician and Silurian age (450 to 410 Ma). This unit can be interpreted as a product of thermal subsidence, suggesting that the underlying rift may have originated in Cambrian time (about 510 Ma). Overlying younger sediments and intrusives in the basin reveal a history that can be linked to the Phanerozoic evolution of the Andes and include a Devonian sequence (about 390 Ma), perhaps related to a Patagonian collision, and a thick Carbo-Permian sequence (320 to 260 Ma) deposited at the time of collision between Gondwanaland and Laurentia. Renewed rifting and a thick sedimentary sequence near the Amazon mouth records the opening of the South Atlantic at about 130 Ma and later South Atlantic continental margin history.

We suggest that the Sub-Amazonal Rift originated as a result of continental collision along the margin of the West African Craton. The West African Craton was involved in arc and continental collisions along its entire periphery during latest Precambrian and Cambrian times between 700 and 500 Ma. This activity culminated latest and was most intense in an area near the site of the present mouth of the Amazon River, where the suture zone marking final continental collision is cryptic for a distance of 1500 km between Ghana and Sierra Leone. This cryptic suture zone includes the entire Sao Luis province boundary in Brazil.

The coincidence in time between rift formation and continental collision, location of the rift at the site of the most intense tectonism, and its trend at a high angle to the collisional suture zone lead us to conclude that the Sub-Amazonal Rift originated as a result of the Pan-African collision. This conclusion adds one more to the growing list of intracontinental rift systems that have been attributed to local modification of within-plate stress as a result of continental collision. Rifts of this origin, which have been called impactogens, include those of the active Rhine, Baikal, and Shanxi systems, as well as those of the 1.0 Ga Mid-Continental rift system of North America.     

Syn‐rift sequence development in a fault‐controlled embayment (Early Permian Irwin River Coal Measures,Northern Perth Basin,Western Australia)

Stratigraphic patterns and sequence development in tectonically active extensional basins remain poorly documented in comparison with passive‐margin settings. Rift basin fills are generally characterized by coarsening‐upward trends in response to the rapid creation of accommodation by extensional faulting, and the progressive filling of graben during more quiescent periods. The Early Permian Irwin River Coal Measures in the Northern Perth Basin (Western Australia) record a complex stratigraphic arrangement of conglomerate, sandstone, mudstone and coal, and have been attributed to delta plain depositional environments that developed in a cool–temperate climatic setting during syn‐rift activity. Sedimentary analysis of outcrop and core data from the fault‐bounded Irwin Terrace is used to distinguish nine facies associations reflecting deposition in braided rivers, fixed‐anastomosed channel belts, tide‐influenced coastal environments and storm‐affected distal bays. The broader depositional system is interpreted as a morphologically asymmetrical tide‐dominated embayment with a fluvial and wave influence. The stratigraphic architecture of the Irwin River Coal Measures was strongly influenced by the evolving rift basin margin. Fault reactivation of the major basin‐bounding Darling Fault in the early syn‐rift phase caused footwall uplift and the inception of transverse palaeo‐valleys occupied by braided fluvial systems. Fault block subsidence during the subsequent balanced, backstepping and drowning phases resulted in a dominantly retrogradational stacking pattern indicating progressive flooding of marginal‐marine areas and culminating in deposition of distal marine elements. In the active rift basin, it is proposed that preservation of a shallow‐marine syn‐rift sequence was promoted by the geomorphological confinement of the embayed system increasing tidal current acceleration and hampering transgressive ravinement. The proposed sequence model demonstrates that transgressive successions can develop in the early syn‐rift phase in response to footwall uplift and tectonic subsidence. The syn‐rift sequence recording the filling of an embayment on a rift basin margin may be applied in similar tectonic and/or depositional contexts worldwide.     

珠江口盆地L凹陷裂陷期始新统文昌组沉积充填模式*

珠江口盆地L凹陷始新统文昌组处于勘探初期,钻井资料较少且分布不均,基于多井多资料的常规沉积相研究方法受到限制,对于层序地层和沉积体系没有系统研究,本次研究充分利用地震、测井以及岩心资料,在全区开展地震相研究工作,井震结合对沉积相展布进行研究,建立裂陷期文昌组沉积演化模式。结果表明: L凹陷裂陷期文昌组划分为3个三级层序,8个体系域;根据三级层序体系域内部地震反射外部形态和内部反射特征差异,识别出充填、席状、楔形、块状、丘形5种地震相类型;通过分析岩心相、测井相以及各种地震相特征,井震结合将地震相转为沉积相,识别出辫状河三角洲、扇三角洲、湖相等沉积相;初始裂陷期为小盆小湖模式,凹陷分割性较强,主要为近源扇三角洲粗碎屑沉积,强烈裂陷早期为大盆浅湖模式,洼陷连通,主要为辫状河三角洲沉积,强烈裂陷中晚期为大盆深湖模式,主要对应半深湖泥岩沉积,弱裂陷期主要为大盆浅湖模式,主要对应大规模长轴辫状河三角洲充填沉积体系。     

陆相伸展盆地的层序类型、结构和序列与充填模式--以冀中坳陷下第三系为例

陆相层序受自然地理景观、影响地层发育的地质营力及地层类型等因素影响,因此层序类型多种多样。在冀中坳陷同伸展期发育洪积层序、湖泊层序和冲积层序等三种层序类型。洪积层序是盆地伸展初期地貌反差较大物源供给充分气候干旱条件下发育的一种陆相层序类型,以冲积扇沉积为主,山高盆窄,汇水湖泊面积较小;湖泊层序发育在盆地强烈伸展基底快速沉降气候湿润湖泊水域宽深时期,湖泊水域宽,连通好,湖水深,是烃源岩发育的黄金时期。湖泊层序以湖泊沉积为主,其次为河流和少许冲积扇沉积。冲积层序是在盆地伸展末期地貌反差强度减弱物源距离逐渐加大时的沉积产物,主要为干旱气候条件下的河流、三角洲沉积,湖泊沉积局限。研究表明,影响陆相层序形成的构造、物源、气候等因素与湖泊水体或水平面变化构成一种多元“函数”关系,湖平面变化是上述因素的综合体现。陆相断陷盆地的层序结构大多与湖泊水体之间存在密切联系,因此层序的结构以三分为主。受地壳构造运动控制,断陷盆地发育的层序具有序列性,即下部洪积层序、中部湖泊层序和上部冲积层序。这种序列性是盆地充填对地壳幕式伸展的沉积响应。在盆地充填过程中,不同类型的陆相层序其体系域发育程度具有较大差异。一般地,洪积层序的低位域沉积?     

饶阳凹陷下第三系层序类型及发育模式

根据陆相地层层序在地震剖面、电测曲线上的识别标志、岩石类型组合特点以及古生物等方面的特征，将饶阳凹陷在下第三系划分出了三个二级层序、十个三级层序。其中层序Ⅰ、Ⅱ为裂谷初始期湖泊层序，层序Ⅲ、Ⅳ、Ⅴ为裂谷强活动期湖泊层序，层序Ⅵ为气候层序，层序Ⅷ、Ⅸ、Ⅹ为河流层序。其中裂谷期湖泊层序可以划分为三个体系域，即低位域、湖侵域和高位域，而河流层序可划分为基准面上升体系域和基准面下降体系域，针对研究区目的层段所划分层序发育的特点，在层序地层单元划分和对比的基础上，对不同层序类型层序的发育模式进行了总结。