二连盆地吉尔嘎朗图凹陷下白垩统赛汉塔拉组层序地层及聚煤特征

二连盆地吉尔嘎朗图凹陷是一个陆相断陷聚煤盆地,下白垩统赛汉塔拉组是其主要含煤地层,作者利用岩心、钻孔资料对其岩相类型、沉积相、层序地层及聚煤作用特征进行研究。(1)赛汉塔拉组主要由砂砾岩、砂岩、粉砂岩、泥岩、碳质泥岩及厚层褐煤组成,发育扇三角洲平原相、扇三角洲前缘相、辫状河三角洲平原相、辫状河三角洲前缘相、滨浅湖相,分别属于扇三角洲沉积体系、辫状河三角洲沉积体系和湖泊沉积体系。(2)识别出2种层序界面:不整合面和下切谷冲刷面,将赛汉塔拉组划分为2个三级层序。从层序Ⅰ到层序Ⅱ,煤层厚度逐渐增大,聚煤作用逐渐增强。(3)在滨浅湖环境下厚煤层主要形成于湖侵体系域早期,在扇/辫状河三角洲环境下厚煤层主要形成于湖侵体系域晚期,煤层厚度在凹陷中部最大,向西北和东南方向均变小。聚煤作用明显受基底沉降作用影响,可容空间增加速率与泥炭堆积速率相平衡,从而形成了区内巨厚煤层。     

内蒙古二连裂谷盆地“同盆多类型"铀矿床组合与找矿方向

自20世纪90年代开始,核工业部门在二连盆地中开展了广泛的铀矿找矿工作,在乌兰察布和马尼特2个坳陷中发现了多个不同类型的铀矿床。文章从裂谷盆地的发展演化入手,分析了二连盆地构造演化阶段和各阶段中沉积充填类型特征。根据构造-沉积-含铀含氧流体在时空上的耦合作用及其结果,初步建立了早白垩世早期腾格尔组中含煤(砂)泥岩型道尔苏矿床、侧向氧化和垂向氧化形成的赛汉组中古河道砂岩型巴彦乌拉和赛汉高毕矿床、以及晚白垩世二连组中由蒸发沉积-成岩-热流体改造形成的努和廷矿床等"同盆多类型"铀矿成矿模型。同时,依据铀矿床成矿地质作用和地质特征,以及不同类型铀矿化发育的空间部位特点,指出了"同盆多类型"铀矿在盆地凹陷中发育的有利空间位置,总结了裂谷盆地不同阶段的"同盆多类型"铀矿床组合规律,为在东北亚地区类似盆地中找寻相似的铀矿床组合指明了方向。     

二连盆地中部古河谷砂岩型铀矿成矿特征及潜力分析

二连盆地早白垩世末期断拗转换的构造应力场背景,为赛汉组上段古河谷沉积的发育创造了有利的地质条件。赛汉组上段古河谷沉积是在下段辫状河三角洲沉积的基础上演化而成,由于湖泊沉积衰亡,形成了长流程的古河道砂体,为铀成矿提供了理想的赋矿空间。晚白垩世-古新世长时间的沉积间断,有利于氧化带的发育。因此,古河谷砂体和氧化带控制了盆地内的铀成矿。笔者通过以哈达图、赛汉高毕和巴彦乌拉铀矿床的对比分析,建立了二连盆地3种不同古河谷类型的铀成矿模式,并对其进行了潜力分析,指出找矿的方向。     

二连盆地川井坳陷构造演化对砂岩型铀矿成矿作用的约束

川井坳陷位于二连盆地西部,坳陷内目的层赛汉组上段发育辫状河、辫状河三角洲-湖沼沉积,砂体发育。受构造、构造演化影响,在坳陷东部发育晚白垩世苏海布龙剥蚀窗口,在坳陷西部白音查干地区发育古近纪剥蚀窗口,剥蚀窗口控制了后生含铀含氧流体向盆地内入渗参与成矿,找矿类型为赛汉期斜坡带型及古河谷型。东西二个剥蚀窗口的发现,对合理解释已发现的矿化异常、找矿预测模型的构建提供了基础。通过构建坳陷三位一体找矿预测模型,预测了苏海布龙、白音查干西及包龙凹陷东三个铀成矿远景区。     

二连盆地中东部含铀古河谷构造建造及典型矿床成矿模式研究

二连盆地为中国北方重要的聚煤沉积盆地,同时也发育赛汉组古河谷,古河谷在盆地内呈北东向带状展布,河谷内发育巴彦乌拉、赛汉高毕及哈达图等多个铀矿床。铀矿床具有"同河谷多矿床、同河谷多类型"的特点。作者通过对含铀古河谷构造-建造的研究,将赛汉组古河谷与铀成矿有关的构造演化划分为6个阶段。沉积前断陷期构造形成了古河谷建造沉积的带状谷地;断坳转换期湖相沉积的灰色泥岩,为铀成矿间接提供了还原物质;坳陷期沼泽化沉积,为铀成矿提供了直接还原介质;赛汉组上段热-重力沉降期河流、辫状河三角洲沉积,形成主要的铀储层。挤压隆升剥蚀期,受构造掀斜抬升,影响了成矿作用的类型及规模;成矿后期的热沉降期,导致新一轮的沉积充填,起到保矿的作用。通过对赛汉组沉积体系、砂分散体系等特征的研究,发现下白垩统赛汉组下段沿短轴方向主要发育冲积扇-扇三角洲-湖沼沉积体系,长轴方向发育辫状河三角洲-湖沼沉积体系。赛汉组上段主要发育河流沉积体系,砂体较发育,沿古河谷呈朵状、带状分布,矿床主要产于赛汉组上段古河谷砂体内。建立了赛汉组古河谷内典型矿床的矿床成矿模式,将赛汉组古河谷的矿床成矿模式划分为巴彦乌拉潜水-层间氧化式、赛汉高毕潜水氧化式及哈达图层间氧化式。     

鄂尔多斯盆地华池地区中侏罗统延安组延9油层组河流沉积及演化

据新的地层划分方案及大量钻井、露头和岩心资料,详细研究了鄂尔多斯盆地华池地区延安组延9油层组（Y9）沉积体系特征及演化,认为延9油层组主要为河流沉积,是延10油层组的继承与发展,发育有辫状河、辫状型曲流河和网状河3种类型的河流。Y39油层是辫状河发育的油层,Y29油层在继承Y39油层河流的基础上发育辫状型曲流河,Y19油层则是在前两期逐渐填平补齐之后,在准平原条件下发育的网状河沉积。华池地区延9油层组发育辫状河-辫状型曲流河和网状河两种河流沉积模式。     

南海琼东南盆地崖13-1气田古近系陵水组海陆过渡带沉积特征及演化*

南海北部琼东南盆地中的众多凹陷均有海陆过渡相沉积,沉积相类型包括海湾辫状河三角洲和河口湾-潮坪。本次研究以高分辨率层序地层学理论为指导,将崖13-1气田古近系渐新统陵水组三段及二段各划分为1个长期基准面旋回,并在其内部进一步识别出10个中期基准面旋回(S1-S10)。在等时地层格架内,对陵水组三段及陵水组二段发育的沉积相特征及演化进行深入的探讨。陵水组三段沉积时期,研究区主要发育海湾辫状河三角洲沉积,其具有独特的层理构造、富含泥质纹层以及遗迹化石丰富。该沉积体系自下而上潮汐作用越来越强,早期以河流作用为主(S1-S4),中期为河流和潮汐混合作用(S5-S6),晚期逐渐过渡到以潮汐作用占主导(S7-S8)。陵水组二段沉积时期,研究区发生全面海侵,沉积作用方式及沉积特征更加复杂,生物成因构造更加独特,本次研究将其解释为河口湾-潮坪沉积(S9-S10)。研究表明,区域海平面的不断上升是研究区沉积相从海湾辫状河三角洲演化到河口湾-潮坪的主要控制因素。     

Allogenic and autogenic controls on facies and stratigraphic architecture of the Lower Jurassic Mashabba Formation,Gebel Al-Maghara,North Sinai,Egypt

The Lower Jurassic Mashabba Formation crops out in the core of the doubly plunging Al-Maghara anticline, North Sinai, Egypt. It represents a marine to terrestrial succession deposited within a rift basin associated with the opening of the Neotethys. Despite being one of the best and the only exposed Lower Jurassic strata in Egypt, its sedimentological and sequence stratigraphic framework has not been addressed yet. The formation is subdivided informally into a lower and upper member with different depositional settings and sequence stratigraphic framework. The sedimentary facies of the lower member include shallow-marine, fluvial, tidal flat and incised valley fill deposits. In contrast, the upper member consists of strata with limited lateral extension including fossiliferous lagoonal limestones alternating with burrowed deltaic sandstones. The lower member contains three incomplete sequences (SQ1-SQ3). The depositional framework shows transgressive middle shoreface to offshore transition deposits sharply overlain by forced regressive upper shoreface sandstones (SQ1), lowstand fluvial to transgressive tidal flat and shallow subtidal sandy limestones (SQ2), and lowstand to transgressive incised valley fills and shallow subtidal sandy limestones (SQ3). In contrast, the upper member consists of eight coarsening-up depositional cycles bounded by marine flooding surfaces. The cycles are classified as carbonate-dominated, siliciclastic-dominated, and mixed siliciclastic-carbonate. The strata record rapid changes in accommodation space. The unpredictable facies stacking pattern, the remarkable rapid facies changes, and chaotic stratigraphic architecture suggest an interplay between allogenic and autogenic processes. Particularly syndepositional tectonic pulses and occasional eustatic sea-level changes controlled the rate and trends of accommodation space, the shoreline morphology, the amount and direction of siliciclastic sediment input and rapid switching and abandonment of delta systems.     

The Nuheting deposit,Erlian Basin,NE China: Synsedimentary to diagenetic uranium mineralization

Sedimentary units deposited during the post-rift stage of the Erlian Basin located in northeast China present an alternation of sandstone and mudstone layers. This sedimentological architecture is at the origin of confined permeable reservoirs hosting sandstone-type uranium deposits. The study of the Nuheting deposit offered the opportunity to identify synsedimentary/early diagenetic uranium concentrations and diagenetic mineralization hosted in mudstone-dominated layers of the Erlian Formation, indicating that a stock of uranium was present in the basin prior to the genesis of sandstone-hosted uranium deposits. Therefore, this pre-existing stock may constitute a significant source of uranium for the formation of roll front deposits present in other parts of the Erlian Basin.Detailed petrographic and geochemical study of drill-core samples from the Nuheting deposit led to the characterization of different stages related to the formation of the uranium ore bodies and allowed to propose a new metallogenic model. Uranium mineralization of the Nuheting deposit is mainly hosted in dark gray silty mudstone of wetland depositional environment of the Late Cretaceous Erlian Formation. Petrographic observations and EMP analyses evidenced that a significant amount of uranium was associated with clay minerals (interstratified clays, smectite, chlorite, palygorskyte, illite and kaolinite), either adsorbed on mineral surfaces as U (VI) ions or reduced mainly as UO₂ nano to microcrystals disseminated in the clayey matrix, which corresponds to synsedimentary/early diagenetic concentrations. Trace elements on pyrite analyzed by LA-ICPMS, petrographic observations and whole-rock geochemical data led to the characterization of a diagenetic uranium mineralization. High As (1–50 ppm), Mo (10–500 ppm) and Se concentrations in the whole rock and the incorporation of these elements in pyrite highlight reducing conditions within the host-rocks during the diagenesis of the Erlian Formation. During the early diagenetic stage, uranium was either desorbed from clay minerals and organic materials to be reduced or directly reduced and precipitated as P-rich coffinite and pitchblende on pyrite crystals. During the late diagenetic stage, uranium was redistributed in situ and locally deposited mainly as coffinite on pyrites. Finally, an epigenetic stage of cementation was identified with sulfate and carbonate minerals, which may enclose some uranium minerals. This epigenetic stage of fluid circulation may be responsible for a minor uranium remobilization. Therefore, the Nuheting deposit experienced three main stages: (i) a synsedimentary/early diagenetic uranium concentration and mineralization, (ii) a late diagenetic in situ uranium remobilization and deposition on pyrite and (iii) an epigenetic cementation. Rock-Eval pyrolysis indicates that the organic matter contained in host-rocks of the Nuheting deposit is of type IV, inherited from land plant, and do not contain free hydrocarbons (very low S1). Therefore, our results do not support that migrated hydrocarbons were involved as a reducing agent for uranium mineralization.     

吉尔嘎朗图凹陷宝饶洼槽下白垩统层序地层与沉积体系

运用高分辨率层序地层学原理和方法,通过对钻井和地震资料的综合分析,在二连盆地吉尔嘎朗图凹陷下白垩统中识别出1个超长期基准面旋回(二级层序)SSC1和5个长期基准面旋回(三级层序):LSC1,LSC2,LSC3,LSC4,LSC5,分析了各旋回的发育特征。识别出五种类型的沉积体系:滨浅湖近岸水下扇、较深水湖浊积扇、滨浅湖扇三角洲、滨浅湖辫状河三角洲和河流沉积体系,并在等时地层格架内分析了各基准面旋回的沉积体系构成和储层砂体的发育情况。综合分析生、诸、盖条件后认为,在垂向上,LSC3旋回为本区最有利的储集层段,在平面上,本区的油气勘探应主要寻找宝饶构造带辫状河三角洲前缘砂体,主要储层砂体类型为前缘分流水道砂和前缘席状砂。     

鄂尔多斯盆地西南缘上三叠统延长组层序地层学与砂体成因研究

以鄂尔多斯盆地西南缘延长组为例,运用高分辨率层序地层学原理,对延河等露头沉积特征进行深入研究。研究认为不整合面、冲刷侵蚀面、岩性岩相转换面和湖泛面为重要的层序界面,并划分出1个超长期基准面旋回,5个长期基准面旋回及17个中期基准面旋回。延长期东、西两岸发育河流—三角洲沉积体系,东北部主要为曲流河、曲流河三角洲体系;西南主要发育辫状河及辫状河三角洲沉积体系。有利储集砂体主要为水下分流河道成因、水下分流河道—河口坝复合成因、河口坝成因和滑塌浊积扇成因等4种类型。研究认为,随湖平面变化,在基准面升降过程中,可容纳空间(A)与沉积物补给量(S)的比值(A/S)影响不同物源方向沉积体系的分布,并建立了沉积演化分布模式。     

Depositional facies,environments and sequence stratigraphic interpretation of the Middle Triassic–Lower Cretaceous (pre-Late Albian) succession in Arif El-Naga anticline,northeast Sinai,Egypt

The Middle Triassic–Lower Cretaceous (pre-Late Albian) succession of Arif El-Naga anticline comprises various distinctive facies and environments that are connected with eustatic relative sea-level changes, local/regional tectonism, variable sediment influx and base-level changes. It displays six unconformity-bounded depositional sequences. The Triassic deposits are divided into a lower clastic facies (early Middle Triassic sequence) and an upper carbonate unit (late Middle- and latest Middle/early Late Triassic sequences). The early Middle Triassic sequence consists of sandstone with shale/mudstone interbeds that formed under variable regimes, ranging from braided fluvial, lower shoreface to beach foreshore. The marine part of this sequence marks retrogradational and progradational parasequences of transgressive- and highstand systems tract deposits respectively. Deposition has taken place under warm semi-arid climate and a steady supply of clastics. The late Middle- and latest Middle/early Late Triassic sequences are carbonate facies developed on an extensive shallow marine shelf under dry-warm climate. The late Middle Triassic sequence includes retrogradational shallow subtidal oyster rudstone and progradational lower intertidal lime-mudstone parasequences that define the transgressive- and highstand systems tracts respectively. It terminates with upper intertidal oncolitic packstone with bored upper surface. The next latest Middle/early Late Triassic sequence is marked by lime-mudstone, packstone/grainstone and algal stromatolitic bindstone with minor shale/mudstone. These lower intertidal/shallow subtidal deposits of a transgressive-systems tract are followed upward by progradational highstand lower intertidal lime-mudstone deposits. The overlying Jurassic deposits encompass two different sequences. The Lower Jurassic sequence is made up of intercalating lower intertidal lime-mudstone and wave-dominated beach foreshore sandstone which formed during a short period of rising sea-level with a relative increase in clastic supply. The Middle-Upper Jurassic sequence is represented by cycles of cross-bedded sandstone topped with thin mudstone that accumulated by northerly flowing braided-streams accompanying regional uplift of the Arabo–Nubian shield. It is succeeded by another regressive fluvial sequence of Early Cretaceous age due to a major eustatic sea-level fall. The Lower Cretaceous sequence is dominated by sandy braided-river deposits with minor overbank fines and basal debris flow conglomerate.     

内蒙古二连盆地洪浩尔舒特凹陷白垩系火山岩储集层

内蒙古二连盆地火山岩分布极为广泛,在古生界（含变质岩） 及中生界的侏罗系和白垩系均有分 布。位于盆地内乌尼特坳陷的洪浩尔舒特凹陷发育有３套火山岩,主要分布在白垩系阿尔善组上段、阿尔善组 下段和腾格尔组一段,火山岩主要为安山岩,次为凝灰岩和少量火山角砾岩。火山岩储集空间类型主要为气孔 和火山灰溶孔,孔缝组合类型有孔隙型、裂缝-孔隙型、孔隙-裂缝型和裂缝型。储集层物性受火山岩岩相、 成岩作用和构造活动影响,以岩相影响最显著。储集层发育总体上中央洼槽中部和东部较好。     

新汶凹陷官庄组沉积演化特征

通过对研究区沉积构造等相标志的研究,以层序地层学和沉积学原理为指导,结合室内岩石薄片、粒度分析,识别出冲积扇、辩状河和湖泊3种沉积相类型.并对官庄组的沉积相垂向演化和平面展布有了系统的认识.研究结果表明:新汶凹陷官庄组自下而上发育冲积扇-辩状河-湖泊和冲积扇两大沉积体系.沉积演化经历了早期凹陷掀斜下沉时的冲积扇、辩状河沉积,中期凹陷扩张阶段的湖泊相沉积,晚期凹陷收缩时的冲积扇进积沉积.     

二连盆地白音查干凹陷下白垩统阿尔善组-都红木组层序地层

层序地层学是岩性-地层油气藏勘探研究的核心技术之一。为深入开展二连盆地白音查干凹陷岩性-地层油气藏勘探,在前人研究成果基础上,通过研究区200多口井的精细地层对比和33口井759.42 m岩心的详细观察及区域构造-沉积演化分析,综合运用构造、古生物、岩性、测井以及地震反射等5个方面的特征,对白音查干凹陷(主要是西部次凹)油气勘探的主要目的层下白垩统阿尔善组—都红木组的层序发育特征进行再认识,对层序界面的性质进行重新厘定。将白音查干凹陷下白垩统阿尔善组—都红木组划分为2个超长期层序(分别对应于阿尔善组—腾格尔组和都红木组)和5个长期层序(分别对应于阿尔善组一段、阿尔善组二段、腾格尔组、都红木组一段和都红木组二段~三段);提出白音查干凹陷下白垩统腾格尔组长期层序的底界面为一连续沉积的整合面,不能构成油气运移的良好通道,即在腾格尔组底部即使圈闭条件良好(如锡40井—锡43井区),但也会因缺乏良好的油气运移通道致使圈闭中供油不足而不能成藏。     

Sequence stratigraphy of the Lower Cenomanian Bahariya Formation, Bahariya Oasis, Western Desert, Egypt

The Lower Cenomanian Bahariya Formation corresponds to a second-order depositional sequence that formed within a continental shelf setting under relatively low-rate conditions of positive accommodation (< 200 m during 3–6 My). This overall trend of base-level rise was interrupted by three episodes of base-level fall that resulted in the formation of third-order sequence boundaries. These boundaries are represented by subaerial unconformities (replaced or not by younger transgressive wave ravinement surfaces), and subdivide the Bahariya Formation into four third-order depositional sequences.

The construction of the sequence stratigraphic framework of the Bahariya Formation is based on the lateral and vertical changes between shelf, subtidal, coastal and fluvial facies, as well as on the nature of contacts that separate them. The internal (third-order) sequence boundaries are associated with incised valleys, which explain (1) significant lateral changes in the thickness of incised valley fill deposits, (2) the absence of third-order highstand and even transgressive systems tracts in particular areas, and (3) the abrupt facies shifts that may occur laterally over relatively short distances. Within each sequence, the concepts of lowstand, transgressive and highstand systems tracts are used to explain the observed lateral and vertical facies variability.

This case study demonstrates the usefulness of sequence stratigraphic analysis in understanding the architecture and stacking patterns of the preserved rock record, and helps to identify 13 stages in the history of base-level changes that marked the evolution of the Bahariya Oasis region during the Early Cenomanian.     

Stratigraphy and architecture of the Upper Triassic Ischigualasto Formation,Ischigualasto Provincial Park,San Juan,Argentina

The Ischigualasto Formation in northwestern Argentina contains abundant fluvial channel sandstones, overbank mudstones, and paleosols that were deposited in a northwest-trending continental-rift basin during Late Triassic time. In the study area the formation progressively thins from ～700 m in the west to ～400 m in the east, over a distance of 7 km. This thinning is accompanied by a relative decrease in the abundance of fluvial channel sandstones and an increase in mud-rich overbank deposits and paleosols. While preserved channel deposits in the formation are highly variable in terms of their size and stratigraphic distribution, four general channel forms can be recognized based on their overall cross sectional geometry and internal sedimentary structures. Of these, the dominant channel-body types are interpreted as the deposits of sandy multi-channel fluvial systems. The internal stratigraphic architecture of the Ischigualasto Formation indicates that during deposition, the central part of the basin was the location of a long-lived, north flowing, fluvial channel belt that received relatively continuous channel and proximal overbank deposition. To the east, however, channel-related deposition was more infrequent, resulting in enhanced pedogenic modification of alluvial deposits. The overall thickness and facies trends observed in the Ischigualasto Formation most likely correspond to variations in fault-related accommodation development within the basin during the time of deposition.     

苏北盆地东部凹陷上白垩统泰州组沉积相*

苏北盆地是在晚白垩世发育起来的箕状断陷盆地。上白垩统泰州组（K₂t）为东部凹陷发育初期形成的一套碎屑岩沉积地层,自下而上总体构成由粗到细的沉积旋回。通过对区内52口探井的录井、测井和岩心资料综合分析,认为泰州组主要发育辫状河三角洲、曲流河三角洲及湖泊相3种沉积相类型,在此基础上又进一步识别出7种亚相和12种微相。泰州组分为两段,泰州组一段沉积早、中期为辫状河三角洲沉积,晚期转变为(曲流河)三角洲沉积;泰州组二段早期为深湖—半深湖沉积,中晚期为浅湖亚相。伴随湖平面的反复升降,表现出明显的多旋回性。研究区泰州组一段表现为典型的退积型三角洲沉积。通过进一步研究泰州组一段各沉积时期沉积相的平面分布及演变特征,指出在梁垛—安丰—李堡一带沉积砂体发育,是油气储集层发育的有利地区。     

Stratigraphic evolution of the nearshore to fluvial plain of the Upper Cuyo Group,Neuquén,Argentina

The upper portion of the Cuyo Group in the Zapala region, south‐eastern Neuquén Basin (Western Argentina), encompasses marine and transitional deposits (Lajas Formation) overlain by alluvial rocks (Challacó Formation). The Challacó Formation is covered by the Mendoza Group above a second‐order sequence boundary. The present study presents the stratigraphic framework and palaeophysiographic evolution of this Bajocian to Eo‐Calovian interval. The studied succession comprises the following genetic facies associations: (i) offshore and lower shoreface–offshore transition; (ii) lower shoreface; (iii) upper shoreface; iv) intertidal–subtidal; (v) supratidal–intertidal; (vi) braided fluvial to delta plain; (vii) meandering river; and (viii) braided river. The stratigraphic framework embraces four third‐order depositional sequences (C1 to C4) whose boundaries are characterized by the abrupt superposition of proximal over distal facies associations. Sequences C1 to C3 comprise mostly littoral deposits and display well‐defined, small‐scale transgressive–regressive cycles associated with fourth‐order depositional sequences. Such high‐frequency cycles are usually bounded by ravinement surfaces associated with transgressive lags. At last, the depositional sequence C4 delineates an important tectonic reorganization probably associated with an uplift of the Huincul Ridge. This is suggested by an inversion of the transport trend, north‐westward during the deposition of C1 to C3 depositional sequences (Lajas Formation) to a south‐west trend during the deposition of the braided fluvial strata related to the C4 depositional sequence (Challacó Formation).     

内蒙古二连盆地巴彦宝力格煤田下白垩统赛汉塔拉组层序—古地理与聚煤作用*

二连盆地巴彦宝力格煤田蕴藏着丰富的煤炭和煤层气资源。利用钻孔和测井资料对赛汉塔拉组层序格架下的古地理演化特征和聚煤作用进行研究,识别出3种层序界面类型: 区域不整合面、河道下切谷冲刷面和对应整合面,将赛汉塔拉组划分为2个三级层序,厚煤层主要发育于层序Ⅰ湖侵体系域早期和晚期。采用单因素分析多因素综合作图法,恢复了层序格架下的古地理格局,古地理单元为冲积扇、扇三角洲平原和滨浅湖。有利聚煤环境为扇三角洲平原与滨浅湖过渡带、滨浅湖,具有合适的基底沉降速率并且受到较小的陆源碎屑影响。从层序Ⅰ到层序Ⅱ,煤层厚度减小,聚煤作用减弱;多层厚煤层的形成受基底沉降震荡性、周期性的影响,受可容空间增加速率与泥炭堆积速率比值不断变化的控制。层序Ⅰ发育时期,研究区中部为下一步煤炭资源和煤层气勘探的有利区。