内蒙古西南部石炭系砂坝─泻湖沉积体系的比较沉积学分析

石炭纪内蒙古西南部广泛发育砂坝─泻湖沉积体系,该体系不同时期形成的泻湖沉积物相互叠置?沉积厚度大?沉积层序多样,这在全新世泻湖中难以形成和观察到?依据沉积特征?沉积层序,识别出与现代同类沉积体系相似的四种基本类型:海侵型?海退型?稳定型和局部海侵型?这表明研究全新世砂坝─泻湖体系得出的地层模式有助于识别地质时期的同类沉积体系?由于研究地区石炭纪砂坝─泻湖体系发育于广阔的空间和较长的时间内,它们常成复合类型,如海侵型─局部海侵型?稳定型─局部海侵型?此外,全新世稳定型砂坝─泻湖体系的上覆和下优层皆为陆相,但是石炭系同类沉积体系在同一地区连续叠置,这是长时期构造持续下陷和岸线相对稳定的反映?海侵型砂坝─泻湖体系形成于海侵层序中,泻湖沉积物的厚度大于砂坝沉积物的厚度,据此,建立了不同于现代同类沉积体系的地层模式?     

A Miocene-restricted platform of the Zibane zone (Saharan Atlas,Algeria), depositional sequences and paleogeographic reconstruction

Depositional sequences and paleogeographic evolution of the Miocene deposits have been studied in the Zibane zone (Saharan Atlas, Algeria) located at the north of the African platform. During the Miocene, this region corresponded to a fault-bounded collapse area and filled by diversified deposits, showing important lateral facies and thicknesses variations. The studied deposits are divided into five depositional sequences separated by major unconformities. These depositional sequences are well developed in the whole basin and testify a paleogeographic differentiation from E–W, induced by a set of NW-SE-trending old faults inherited from the Atlasic orogeny. The organization and the development of those sequences make it possible to correlate them better to the basin scale, which is integrated in a model of restricted platform intersected by NW-SE faults where the tectonic-sedimentation duality is predominant. These new data point to a paleogeographic evolution different from the one usually admitted environment for this region during Miocene time and plead in favour of a reconsideration of the depositional environments of the post-Burdigalian formations in the Zibane zone of the Algerian Atlasic domain.     

东营凹陷滑塌型重力流沉积分布特征及三角洲沉积对其影响

三角洲沉积为滑塌型重力流的形成提供了物质来源,它对前端滑塌型重力流的沉积分布特征具有重要影响.以东营凹陷洼陷带沙三中亚段三角洲-前端滑塌型重力流沉积为研究对象,综合利用钻井岩心、三维地震、测录井及分析测试等资料,总结不同类型滑塌型重力流沉积特征、识别标志和分布特征,分析三角洲作为物源对滑塌型重力流的形成、沉积类型、沉积特征和分布特征的影响.研究表明,研究区滑塌型重力流沉积主要发育滑动岩、滑塌岩、碎屑流沉积和浊积岩4种类型,不同类型其沉积构造、粒度特征、地球物理特征差异显著.研究区砂质碎屑流沉积最为发育,滑动滑塌沉积次之,浊流沉积和泥质碎屑流沉积少量发育.不同地区重力流沉积发育程度及常见垂向序列存在差异,博兴南坡与辛133区块重力流类型以砂质碎屑流沉积为主,常见多期次砂质碎屑流沉积相邻或相间垂向组合;牛庄南坡与中央隆起带地区类似,由近及远,重力流类型及垂向序列存在较大差异;营11区块以砂质碎屑流沉积和浊流沉积为主,浊流比例相对其他区块较高;丰14区块单井重力流类型整体较单一,为砂质碎屑流沉积或滑塌沉积.三角洲砂泥百分含量控制了滑塌型重力流的沉积类型和沉积特征;三角洲沉积物粒径控制原始前积角大小,前积角越大,滑塌型重力流越发育,但滑移距离相对越近;三角洲的坡折点控制下,滑动滑塌沉积主要分布在斜坡坡脚和同沉积断层附近,浊流沉积主要分布在深水平原,碎屑流沉积在斜坡坡脚-深水平原均有分布;三角洲高的堆积速率通过减小内摩擦力促使滑塌型重力流的形成,其堆积速率与构造沉降速率的差异对滑塌型重力流沉积的垂向叠置和侧向连续性也具有重要影响.      

使用计算机对下塔尔克乌砂岩组中浊积岩(罗马尼亚东喀尔巴阡山)的马尔科夫链分析

如复理石沉积那样的垂向连续型韵律序列的研究能揭示有关生成过程和沉积区域的重要信息。无论不同岩性的垂向组合是否随机的，甚至没有沉积层序的优选次序，也能进行马尔科夫链分析这样的统计分析。此类分析适用于下塔尔克乌砂岩组（罗马尼亚东喀尔巴吁山）的复理石沉积，注意这些沉积物保存的发生程序并给以储存，而那些沉积物（至少被研究的层段）是浊流作用的产物，这些浊积物堆积在水道化沉积亚环境（诸如水道化的中深海扇之类）具良好分带的沉积区中。     

Evolution of depositional settings in the Torrey area during the Smithian (Early Triassic,Utah, USA) and their significance for the biotic recovery

This work focuses on well‐exposed Lower Triassic sedimentary rocks in the area of Torrey (south‐central Utah, USA). The studied Smithian 8 deposits record a large‐scale third‐order sea‐level cycle, which permits a detailed reconstruction of the evolution of depositional settings. During the middle Smithian, peritidal microbial limestones associated with a rather low‐diversity benthic fauna were deposited seaward of the tidal flat siliciclastic red beds. Associated with siliceous sponges, microbial limestones formed small m‐scale patch reefs. During the late middle to late Smithian interval, the sedimentary system is characterized by tidal flat dolostones of an interior platform, ooid‐bioclastic deposits of a tide‐dominated shoal complex, and mid‐shelf bioclastic limestones. Microbial deposits, corresponding to sparse stromatolites formed in the interior platform, are contemporaneous with a well‐diversified marine fauna living in a seaward shoal complex and mid‐shelf area. The nature and distribution of these Smithian microbial deposits are not related to any particular deleterious environmental condition, highlighting that observed patterns of biotic recovery after the end‐Permian mass extinction were directly influenced by depositional settings. Facies evolution and stratal stacking patterns allow us to identify large, medium and small‐scale, as well as elementary depositional sequences. Large‐ and medium‐scale sequences are consistent with sea‐level changes, whereas small‐scale and elementary sequences are better explained by autocyclic processes. Copyright © 2015 John Wiley & Sons, Ltd.     

西藏达金海相碎屑岩的组成、地球化学特征及其构造背景

达金海相碎屑岩出露于西藏冈仁波齐峰山脚下,长期以来,该套岩石与冈底斯砾岩一起被视为印度-亚洲板块碰撞形成的陆相磨拉石.该套岩石组合是由凝灰质粉砂岩、杂砂岩、含砾杂砂岩和砾岩组成的一套深海-浅海相沉积组合.杂砂岩、砾岩碎屑组成与地球化学组成研究表明,该套岩石组合的形成与岛弧的发展密切相关,源区大地构造背景以岛弧为主,但也存在被动大陆边缘和碰撞构造带（蛇绿混杂带）两个不同构造背景的源区.区域上,在该套岩石组合的北侧存在着冈底斯岛弧带,南侧为雅鲁藏布蛇绿混杂带.这些特征共同表明,达金海相碎屑岩是西藏雅鲁藏布缝合带与冈底斯岛弧带之间的日喀则弧前盆地的一部分.     

珠江口盆地惠州地区新生界珠海组和珠江组重力流沉积特征*

通过2口井的岩心观察,在珠江口盆地惠州地区新生界珠海组和珠江组,发现有重力流沉积。该地区重力流沉积的主要特征是：滑塌构造发育广泛,是本区最主要的重力流沉积;液化沉积中泄水构造发育;浊流沉积中鲍马序列不完整。惠州地区的重力流沉积是三角洲前缘砂体垮塌再搬运沉积而形成的。在重力流沉积中还发现有潮汐作用的存在,潮汐作用和重力流沉积伴生。通过对惠州地区重力流沉积特征的研究,认为不能简单地将重力流沉积等同于浊流沉积;重力流沉积不仅局限在深水地区,在相对浅水地区也会发育。建议正确理解鲍马序列并予以合理使用。     

重庆中梁山三叠系飞仙关组三段风暴沉积

本文根据重庆中梁山毛家沟三叠系剖面飞三段(T₁f3)中的沉积序列和沉积构造特征,阐明了该段中具有两个比较完整的风暴岩序列。讨论了风暴作用造成的独特的沉积物类型和沉积标志,并划分出近积风暴岩与远积风暴岩两种类型。本区风暴岩形成于正常浪基面与风暴浪基面之间的陆棚环境。     

山西二叠系河流沉积特征

山西西部二叠系沉积环境以河流为主,除曲流河外,还有为数不多的辫状河与交织河。曲流河以发育曲流沙坝、洪泛平原和决口扇为其特征。辫状河发育河道沙坝沉积,洪泛平原沉积不太发育。交织河以河道稳定为特征,伴有沼泽沉积,是理想的成煤环境。     

准噶尔盆地西北部春光探区白垩系地震沉积学研究*

地震沉积学是精细表征沉积体系时空分布特征的有效手段。本文以准噶尔盆地西北部春光探区为例,首先对白垩系的层序界面和层序展布进行了分析,建立了高分辨层序地层格架,然后综合分析地震、录井、测井、岩心以及分析化验等资料,明确了该区的沉积相类型,最后以地震沉积学思想为指导,利用地层切片等多项技术,对沉积体系进行了精细的刻画。结果表明: (1)春光探区白垩系可以划分为4个三级层序和7个四级层序。(2)白垩系发育扇三角洲、辫状河三角洲、异重流和湖泊4种沉积相类型。(3)通过相位调整,建立了地震振幅与岩性的良好对应关系;利用分频处理、RGB属性融合和地层切片技术,精确地刻画了沉积体系的时空分布。呼图壁组沉积时期,春光探区西南角为扇三角洲,东部为辫状河三角洲和异重流沉积,在切片上可以清晰地观察到蜿蜒曲折的异重流水道及新月形的侧积复合体;胜金口组沉积时期是白垩系湖侵规模最大时期,最有利于东部异重流发育和保存,西南部扇三角洲继续继承性发育;连木沁组沉积时期,由于西南部抬升,只在东部接受沉积,发育辫状河三角洲,先前发育的异重流沉积逐渐萎缩。     

Seismic sedimentology study of the Cretaceous in Chunguang exploration area,northwest of Junggar Basin

Seismic sedimentology is the effective method to depict the spatial and temporal distribution characteristics of sedimentary system. Taking the Chunguang exploration area in the northwest of the Junggar Basin as an example,the sequence boundaries and their distributions were analyzed at first,and the high-resolution sequence framework was thus built. And then the sedimentary types were identified combined with seismic,mud-logging,well-logging,core and analytic data. Under the guidance of seismic sedimentology,the distribution of sedimentary systems were depicted using several techniques including stratal slicing. The results show that: (1)the Cretaceous was divided into four third-order sequences and seven fourth-order sequences in the Chunguang exploration area;(2)four types of sedimentary facies types are identified,including fan delta,braided river delta,hyperpycnal-flow deposits and lake;(3)through the phase adjustment,a good corresponding relationship between seismic amplitude and lithology is established. The frequency decomposition,RGB blending and stratal slicing techniques were carried out,and the spatial-temporal distribution of sedimentary systems in the study area was depicted precisely. During the depositional period of the Hutubi Formation,fan delta was developed in the northwest of the study area,and braided river delta and hyperpycnal-flow deposits were developed in the east,sinuous channels and lateral accretion packages can be observed from the stratal slices. The lake transgression reached the maximum during the depositional period of the Shengjinkou Formation,and it was favorable to development and preservation of hyperpycnal-flow deposits. The inherited fan delta deposits were still developed in the northwest of the study area. Due to the uplift of the northwest area,it could be only developed in the east area with braided deltas and gradually decreased hyperpycnal-flow deposits during the depositional period of the Lianmuqin Formation.     

前陆盆地陆源沉积序列的特征与成因机制

前陆盆地接受的来自毗邻造山带的陆源碎屑沉积是盆山耦合关系研究的主要对象之一.这套沉积通常具有以下3个方面的特征:①在地层剖面中,前陆盆地陆源沉积序列呈向上变粗的趋势,其成因有多种可能,包括源区构造隆升、侵蚀卸栽导致的盆地基底均衡回弹、气候变化、岩性变化等;②构造抬升导致的粗粒相沉积事件与构造事件之间存在时滞,其大小取决于源区基岩剥露速率、侵蚀与搬运条件、沉积区距造山带构造变形前缘之间的距离等因素;③粗粒相沉积在前陆盆地内的分布具有穿时性.重视这些方面的研究,有助于得出有关前陆盆地及毗邻造山带演化的合理结论.     

柴北缘地区层序格架下的沉积特征

中国中西部含油气沉积盆地大多具有前陆盆地层序组合特征,可以识别出前陆层序和非前陆层序。柴达木盆地柴北缘层序地层格架主要包括非前陆层序的侏罗系和古近系以及前陆层序的新近系。通过井剖面层序分析结合有限的地震剖面,可以对柴达木北缘侏罗系划分7套III级层序。古近系—第四系划分11套III级层序。侏罗系属于非前陆期沉积,新近系属于前陆期沉积。通过柴北缘地区层序框架下沉积特征的解剖,表明柴北缘地区非前陆期遗迹化石以缺氧环境化石群为主,沉积相以河流-湖沼体系为特征。前陆期遗迹化石以陆相氧化河湖相环境化石群为主,湖退体系域(RST)冲积扇-河流三角洲-滨浅湖相沉积体系非常发育。柴达木盆地的沉积层序表现为受构造强烈活动和气候变化的影响,强烈活动期潮湿气候下层序表现为山前带发育进积式准层序组,凹陷区形成退积式准层序组。干旱气候配合下的层序表现为多物源更加明显,山前带沉积物供应更加迅速,且沉积中心迁移强烈。     

Stacked fluvial and tide-dominated estuarine deposits in high-frequency (fourth-order) sequences of the Eocene Central Basin, Spitsbergen

Eighteen coastal-plain depositional sequences that can be correlated to shallow- to deep-water clinoforms in the Eocene Central Basin of Spitsbergen were studied in 1 × 15 km scale mountainside exposures. The overall mud-prone (>300 m thick) coastal-plain succession is divided by prominent fluvial erosion surfaces into vertically stacked depositional sequences, 7–44 m thick. The erosion surfaces are overlain by fluvial conglomerates and coarse-grained sandstones. The fluvial deposits show tidal influence at their seaward ends. The fluvial deposits pass upwards into macrotidal tide-dominated estuarine deposits, with coarse-grained river-dominated facies followed further seawards by high- and low-sinuosity tidal channels, upper-flow-regime tidal flats, and tidal sand bar facies associations. Laterally, marginal sandy to muddy tidal flat and marsh deposits occur. The fluvial/estuarine sequences are interpreted as having accumulated as a series of incised valley fills because: (i) the basal fluvial erosion surfaces, with at least 16 m of local erosional relief, are regional incisions; (ii) the basal fluvial deposits exhibit a significant basinward facies shift; (iii) the regional erosion surfaces can be correlated with rooted horizons in the interfluve areas; and (iv) the estuarine deposits onlap the valley walls in a landward direction. The coastal-plain deposits represent the topset to clinoforms that formed during progradational infilling of the Eocene Central Basin. Despite large-scale progradation, the sequences are volumetrically dominated by lowstand fluvial deposits and especially by transgressive estuarine deposits. The transgressive deposits are overlain by highstand units in only about 30% of the sequences. The depositional system remained an estuary even during highstand conditions, as evidenced by the continued bedload convergence in the inner-estuarine tidal channels.     

Variable style of transition between Palaeogene fluvial fan and lacustrine systems, southern Pyrenean foreland, NE Spain

Two Palaeogene fluvial fan systems linked to the south‐Pyrenean margin are recognized in the eastern Ebro Basin: the Cardona–Súria and Solsona–Sanaüja fans. These had radii of 40 and 35 km and were 800 and 600 km² in area respectively. During the Priabonian to the Middle Rupelian, the fluvial fans built into a hydrologically closed foreland basin, and shallow lacustrine systems persisted in the basin centre. In the studied area, both fans are part of the same upward‐coarsening megasequence (up to 800 m thick), driven by hinterland drainage expansion and foreland propagation of Pyrenean thrusts. Fourteen sedimentary facies have been grouped into seven facies associations corresponding to medial fluvial fan, channelized terminal lobe, non‐channelized terminal lobe, mudflat, deltaic, evaporitic playa‐lake and carbonate‐rich, shallow lacustrine environments. Lateral correlations define two styles of alluvial‐lacustrine transition. During low lake‐level stages, terminal lobes developed, whereas during lake highstands, fluvial‐dominated deltas and interdistributary bays were formed. Terminal lobe deposits are characterized by extensive (100–600 m wide) sheet‐like fine sandstone beds formed by sub‐aqueous, quasi‐steady, hyperpycnal turbidity currents. Sedimentary structures and trace fossils indicate rapid desiccation and sub‐aerial exposure of the lobe deposits. These deposits are arranged in coarsening–fining sequences (metres to tens of metres in thickness) controlled by a combination of tectonics, climatic oscillations and autocyclic sedimentary processes. The presence of anomalously deeply incised distributary channels associated with distal terminal lobe or mudflat deposits indicates rapid lake‐level falls. Deltaic deposits form progradational coarsening‐upward sequences (several metres thick) characterized by channel and friction‐dominated mouth‐bar facies overlying white‐grey offshore lacustrine facies. Deltaic bar deposits are less extensive (50–300 m wide) than the terminal lobes and were also deposited by hyperpycnal currents, although they lack evidence of emergence. Sandy deltaic deposits accumulated locally at the mouths of main feeder distal fan streams and were separated by muddy interdistributary bays; whereas the terminal lobe sheets expand from a series of mid‐fan intersection points and coalesced to form a more continuous sandy fan fringe.     

鄂东南早三叠世钙质风暴沉积特征及其初步研究

鄂东南下三叠统地层发育齐全,野外露头连续,是大冶组的命名地(谢家荣,1924),长期以来受到地质学界的关注(图1)。在该地层中,发育多层砾屑灰岩,不同学者对其成因具有不同的解释,有的认为是一种泥皮成因的浅水标志;有的认为是深海盆地边缘或下部斜坡带的重力流沉积。根据我们近年来的研究,认为大部分砾屑灰岩应届风暴流、风暴重力流作用的产物。在野外露头上,风暴沉积现象清晰,风暴作用证据充分。     

北羌塘坳陷冬曲地区上三叠统巴贡组扇三角洲沉积特征

北羌塘坳陷冬曲地区上三叠统巴贡组为一套碎屑岩沉积,在垂向上具有两个向上变粗的充填序列。根据沉积体产出形态和叠置序列、岩石组合与结构、沉积构造及流体性质等沉积特征,确定该套沉积体为扇三角洲相沉积,进而可划分出扇头、扇中、扇尾3个亚相。发育底冲刷构造、粒序层理、平行层理、交错层理等,表明其流体性质既有重力流又有牵引流特征。通过该套扇三角洲沉积体的认识,对研究该区古构造背景、沉积环境及油气地质条件等具有重要意义。     

风火山地区铜矿床特征及成因研究

风火山地区铜矿床位于我国著名的“三江”有色和贵金属成矿带的西段,以往地质工作程度较低,从而影响了人们对该矿床成矿环境及成因的认识。近年来,随着地勘工作特别是地质大调查资源评价工作的深入开展,初步查明了区内风火山群沉积环境、沉积序列及含矿层位,建立了构造格架及构造变形序列。笔者根据野外实践,对该矿床特征及矿床成因进行了分析和总结,认为风火山铜矿床属于砂岩型铜矿床,构成砂岩型铜矿的各铜矿化带,均呈夹层产于风火山群砂泥岩中,含矿层岩性均为浅灰—灰绿色厚—中厚层状细粒(含砾)岩屑石英砂岩夹深灰色薄层碳质泥岩。整个风火山成矿带上各矿化带的形态、矿化体特征基本一致,均呈层状产出。     

中国海岸带晚更新世风成沉积分区、序列特征及其气候-环境意义

本文提出海岸风沙沉积和海岸风尘沉积是晚更新世期间，由东北季风风系控制的风沙流活动所成。每一期风沙流活动的时限不恒定，其盛行风向前缘随着风力衰减而产生风尘沉积，形成海岸风沙—海岸风尘沉积匹配带。中国海岸带自北而南可划分出四个海岸风沙—海岸风尘沉积匹配区。海岸风沙－海岸风尘沉积均具有多发、高频变化特征，与其中交互更叠的土壤层、冲－洪积层、侵蚀间断面等一起，可成为晚更新世期间气候－环境判别的标志。