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1.
虽然地层记录中的内波和内潮汐沉积研究已有30年的研究历史,但尚未涉及深水环境中内波和内潮汐成因研究,不利于对深水复杂水动力环境下各种流体交互作用的深入研究,同时由于已发现研究实例中缺乏生物化石和遗迹化石,从而在很大程度上限制了对内波和内潮汐沉积和油气生成及运移之间的关系研究。本文以鄂尔多斯盆地西缘北部桌子山地区上奥陶统拉什仲组深水沉积为研究对象,在详细的野外观察基础上,采用沉积地球化学和沉积学相结合的方法对该组中发育的内波和内潮汐沉积进行了综合研究。结果表明：拉什仲组中的双向交错层理和浪成波纹层理可相互伴生,多发育在完全或近于完全的鲍玛序列Tc段,其寄主岩性主要为灰绿色薄-中层细砂岩、粉砂岩、黏土质粉砂岩和粉砂质黏土岩;沉积时水体介质具有海水性质总体上不明显、氧化-还原分层、盐度倒置、不受热液影响和水动力较强等现象。结合拉什仲组存在的浊流反射现象认为：拉什仲组沉积于局限海深水斜坡至盆地环境,其内波和内潮汐的形成与低密度浊流反射形成的密度跃层密切相关,具有事件性作用特征,并伴生有大量的生物化石(笔石)及遗迹化石。这种新型内波和内潮汐沉积对于深水牵引流沉积油气勘探具有... 相似文献
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基于对东濮凹陷97口钻井岩心的详细观察和分析,在古近系沙河街组沙三中亚段湖相沉积中识别出滑动、滑塌、碎屑流和浊流共4种类型的重力流沉积。各种类型沉积的主要判识特征如下: (1)滑动沉积以保留部分原始沉积构造、层内准同生小型断裂构造及较大角度的地层倾角(陡倾构造)发育、伴生Skolithos-Palaeophycus遗迹组合或Planolites-Taenidium遗迹组合为主要特征; (2)滑塌沉积以砂岩层顶、底面均与暗色泥岩呈突变接触以及岩层内部发育各种同生软沉积物变形构造(如包卷层理、火焰状构造、泄水构造、液化脉和各种撕裂屑等)为主要鉴别特征;(3)碎屑流沉积以砂岩呈块状构造、顶部发育漂浮砾石、底部泥岩撕裂屑发育并可见“泥包砾”现象、砂岩顶、底面均与暗色泥岩突变接触为特征;滑塌沉积和碎屑流沉积序列的上部常常伴生Mermoides-Parapaleodictyon遗迹组合; (4)浊流沉积以发育完整或不完整的鲍马序列为主要特征,浊积砂体下部见正粒序层理,底面见有冲刷痕、不规则槽模、重荷模等沉积构造,中上部发育深湖沉积中常见的Semirotundichnus-Puyangichnus遗迹组合。综合分析上述各种重力流沉积特征和伴生遗迹化石组合所体现的水深变化规律,认为遗迹化石组合随着湖水深度的增加呈分带性,与重力流沉积随水深增加而出现的滑动—滑塌—碎屑流—浊流沉积序列具有明显的一致性,且伴随重力流沉积而产生的生物扰动作用是增强的。因此,生物扰动构造(遗迹化石)的研究不仅对湖相沉积中储集层物性的分析具有重要意义,而且针对重力流沉积类型的判识还能提供重要的生物遗迹学信息。 相似文献
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本文详细论述了赣西北前寒武系首次发现的深水牵引流内波内潮汐沉积特征的沉积构造、岩石组合和沉积序列。沉积构造主要发育双向和单向交错层理、曲线型和干涉波痕及波状、脉状、透镜状层理;常产于深水重力流之上或与之共生。岩石粒度结构特征为明显的牵引流性质。共划分出双向交错层理砂岩组合,单向交错层理砂岩组合,薄层砂岩——板岩组合和波状、脉状、透镜状细砂岩——粉砂岩——板岩组合;可识别出双向递变、单向递变和对偶层递变序列。在综合研究和分析的基础上,进一步阐述了内波内潮汐沉积与浊流沉积的异同点和相互关系以及内波内潮汐沉积的保存条件、沉积环境和控制机理。深水牵引流内波内潮汐沉积学特征的系统研究,对正确阐明沉积盆地的大地构造背景及形成演化具有重要意义。 相似文献
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内波、内潮汐沉积和复合流沉积是二十余年来在古代深水环境中新发现的一种具牵引流性质的沉积相类型,由于地层沉积记录十分有限,制约了深水底流沉积的沉积学研究。大比例尺实测地质剖面和精细露头测量表明,底流沉积发育于凭祥盆地深水沉积之中,通过对其沉积构造精细剖析和古水流测量,识别出内波、内潮汐沉积和复合流沉积,其中内波、内潮汐沉积以双向交错层理、单向交错层理、透镜状层理为特征,复合流沉积以复合流层理、丘状交错层理和较陡的爬升波纹层理为特征,进一步表明存在浊流和底流的交互作用,为古代地层中的深水底流沉积提供了又一研究实例。 相似文献
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宁夏中奥陶统香山群为一套遭受轻微区域变质的陆源碎屑岩,并夹有少量碳酸盐岩和硅质岩,主要为深水浊流沉积。其中,徐家圈组主要由灰绿色、黄绿色轻变质细砂岩、钙质砂岩及粉砂岩和页岩组成,顶部发育有薄层石灰岩。在该组的中—薄层钙质粉—细砂岩、细粉屑质石灰岩和粉砂质页岩中发现了双向交错层理及纹层倾向与区域斜坡倾向相反或有较大夹角的单向交错层理,其中双向交错层理形态丰富、纹层清晰,其纹层倾向有沿斜坡向上的,有沿斜坡向下的。在深水环境中,这些交错层理不应是等深流沉积或浊流沉积的产物,而应为内波产生的沿斜坡上下水流交替流动所形成的。从沉积背景、沉积构造和古水流等方面对徐家圈组的内波、内潮汐沉积进行了详细的研究,认为其形成于水道不发育的深水斜坡环境,并对斜坡环境中内波、内潮汐沉积中不发育脉状、波状和透镜状层理的现象进行了解释。 相似文献
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贺兰山以南中奥陶统香山群徐家圈组古水流分析 总被引：11，自引：0，他引：11
贺兰山以南中奥陶统香山群为一套遭受轻微区域变质的陆源碎屑岩,并夹有少量碳酸盐岩和硅质岩,属于深海浊流沉积。其下部徐家圈组由灰绿、黄绿色轻变质细粒砂岩、钙质砂岩及粉砂岩和页岩组成,沉积环境为深水斜坡环境,并在该组发现了内波、内潮汐沉积,主要表现为双向交错层理。本文通过对徐家圈组指向沉积构造所显示的古水流资料进行研究,综合分析了香山群徐家圈组沉积时浊流方向和古斜坡方向,并利用古水流资料探讨了内波流和内潮汐流的方向。结果表明,槽模古水流方向从北向南略呈扇形发散状,代表了沉积时的浊流方向;交错层理古水流方向主要分散在NWW—NE之间,可以代表内波流和内潮汐流方向。对古水流平面分布特征进行综合分析,可以判断出沉积时区域斜坡方向与浊流方向基本一致,大致为SSW向,沉积时内波和内潮汐的传播方向则大致为NW向。 相似文献
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《地球科学进展》2019,(12)
深水复合流沉积研究近年来尚处于起步阶段,发现新的实例并探讨复合流沉积构造对环境的指示作用具有重要意义。鄂尔多斯盆地西缘北部内蒙古桌子山地区上奥陶统拉什仲组以深水斜坡至盆地环境下浊流沉积为主,兼有等深流沉积和内波、内潮汐沉积,沉积时具有复杂的水动力条件。在详细的野外观察和测量的基础上,结合已有水槽实验和相关实例的研究成果,对拉什仲组有关复合流沉积构造进行了详细研究。在深水沉积环境中发现了典型的复合流沉积构造,包括复合流层理、准平行层理和小型似丘状交错层理。垂向上可归纳为6种沉积构造序列,分别为:(a)正粒序层—浪成波纹层理—复合流层理;(b)准平行层理—正粒序层—复合流层理;(c)正粒序层—准平行层理;(d)准平行层理—双向交错层理—小型似丘状交错层理;(e)黏土岩中的叠置小型似丘状交错层理和(f)黏土岩中的复合流层理。结合拉什仲组沉积环境和沉积类型,复合流沉积可能为深水环境下浊流、等深流和内波流交互作用形成,依据流体与海底地形的作用,可划分为浊流抑制区(序列a和b)、强交互区(序列c)、内波作用区(序列d)和弱交互区(序列e和f)。该研究对于在地层记录中研究内波、内潮汐与海底地形作用和有关沉积相带划分具有重要意义。 相似文献
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综合运用钻井岩心、测录井等资料,通过岩心观察、薄片鉴定和粒度分析等方法,对渤海湾盆地临南洼陷古近系沙三中亚段深水重力流沉积类型及其沉积特征、沉积模式展开研究。研究表明,临南洼陷沙三中亚段深水重力流沉积主要发育滑塌沉积、碎屑流沉积和浊流沉积3种成因类型。滑塌沉积以包卷层理、液化砂岩脉、阶梯状小断层、变形岩层与未变形岩层叠置为典型特征。碎屑流沉积中砂质碎屑流沉积分布较广,以突变的底部接触面、块状层理、泥岩撕裂屑、土黄色泥砾、突变或不规则的上接触面为典型识别标志。浊流沉积则以正粒序层理、底部冲刷面和槽模、薄层砂泥互层、不完整的鲍马序列为典型识别标志。滑塌沉积主要发育在三角洲前缘斜坡根部,在滑塌沉积前方形成碎屑流沉积,碎屑流向前搬运的过程中,流体被稀释逐渐转化成浊流。滑塌型深水重力流沉积整体分为近源沉积、中部沉积和远源沉积3个部分: 近源沉积主要发育具变形构造的滑塌沉积和厚层块状砂质碎屑流沉积;中部沉积主要发育砂质碎屑流沉积及浊流沉积;远源沉积以薄层浊流沉积为主。 相似文献
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《古地理学报》2017,(3)
综合运用钻井岩心、测录井等资料,通过岩心观察、薄片鉴定和粒度分析等方法,对渤海湾盆地临南洼陷古近系沙三中亚段深水重力流沉积类型及其沉积特征、沉积模式展开研究。研究表明,临南洼陷沙三中亚段深水重力流沉积主要发育滑塌沉积、碎屑流沉积和浊流沉积3种成因类型。滑塌沉积以包卷层理、液化砂岩脉、阶梯状小断层、变形岩层与未变形岩层叠置为典型特征。碎屑流沉积中砂质碎屑流沉积分布较广,以突变的底部接触面、块状层理、泥岩撕裂屑、土黄色泥砾、突变或不规则的上接触面为典型识别标志。浊流沉积则以正粒序层理、底部冲刷面和槽模、薄层砂泥互层、不完整的鲍马序列为典型识别标志。滑塌沉积主要发育在三角洲前缘斜坡根部,在滑塌沉积前方形成碎屑流沉积,碎屑流向前搬运的过程中,流体被稀释逐渐转化成浊流。滑塌型深水重力流沉积整体分为近源沉积、中部沉积和远源沉积3个部分:近源沉积主要发育具变形构造的滑塌沉积和厚层块状砂质碎屑流沉积;中部沉积主要发育砂质碎屑流沉积及浊流沉积;远源沉积以薄层浊流沉积为主。 相似文献
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以下刚果盆地下白垩统巴雷姆阶Pointe Indienne组中段为例,采用深水沉积学理论,结合重力流的最新研究进展,利用研究区最新钻井岩心资料及分析测试数据,对其岩性、沉积构造类型和岩石学特征等进行了探讨分析,识别出研究区广泛存在重力流沉积,并总结了该重力流的深水沉积过程及其砂体发育概念模型。结果表明: 重力流沉积以中—细砂岩为主,砂岩底部发育槽模、重荷模、火焰状构造及球枕构造,砂岩内部有正粒序层理、平行层理、爬升波纹层理、包卷层理、泄水构造及漂浮泥砾;重力流砂岩主要为长石岩屑质石英砂岩,分选差、次棱—次圆状,以悬浮搬运机制为主,砂岩粒度累积概率曲线有全悬浮总体的“一段式”和高悬浮总体的“两段式”可识别出滑动、滑塌、砂质碎屑流、泥质碎屑流和浊流5种重力流流体类型及其在垂向上的6种相序组合类型;研究区重力流砂体横向连续性较好,垂向叠置厚度较厚,可形成规模较大的油气藏。 相似文献
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《Sedimentology》2018,65(5):1800-1825
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The research of deep-water combined-flow deposits is still in its infancy at present, which has great significance for discovering new case study and discussing the indication effects of combined-flow sedimentary structures on depositional environment. The Upper Ordovician Lashenzhong Formation in Zhuozishan area, Inner Mongolia, in the north of western Ordos Basin, is mainly deposited by turbidity currents concomitant with contour currents as well as internal-waves and internal-tides in deep-water slope and basin floor environment which display typical complex hydrodynamic conditions. Here we studied the deep-water combined-flow sedimentary structures of Lashenzhong Formation in detail based on careful field work, combined with the results of flume experiments and other related case studies in literatures. Several combined-flow sedimentary structures were found in deep-water environment, which include combined-flow-ripple lamination, quasi-planar lamination and small-scale hummocky cross-stratification-like structures. These sedimentary structures can be summarized vertically as 6 sedimentary structure successions: normal graded layer through wave-ripple lamination to combined-flow-ripple lamination (a), quasi-planar lamination through normal graded layer to combined- flow-ripple lamination (b), amphibolous normal graded layer overlaying by quasi-planar lamination (c), quasi-planar lamination through bi-directional cross-lamination to small-scale hummocky cross-stratification-like structures (d), amalgamated small-scale hummocky cross-stratification-like structures enveloped claystone (e) and combined- flow-ripple lamination enveloped claystone (f). The origin of deep-water combined-flow deposits perhaps is the interactions of turbidity currents, contour currents and internal-wave currents according to the sedimentary types and environment in Lashenzhong Formation. Based on the interactions between sedimentary currents and sea floor topography, four sedimentation zones were suggested: turbidity currents restrained zone (succession a and b), strong interaction zone (succession c), internal-wave action zone (succession d) and weak interaction zone (succession e and f). This study will be helpful for the study of interactions of internal-waves and internal-tides with sea floor topography, and related sedimentation zone division in geological records. 相似文献
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Earthquake, as disastrous events in geological history, can be recorded as soft-sediment deformation. In the Palaeogene of
the East China Sea shelf, the soft-sediment deformation related to earthquake event is recognized as seismic micro-fractures,
micro-corrugated laminations, liquefied veins, ‘vibrated liquefied layers’, deformed cross laminations and convolute laminations,
load structures, flame structures, brecciation, slump structures and seismodisconformity. There exists a lateral continuum,
the wide spatial distribution and the local vertical continuous sequences of seismites including slump, liquefaction and brecciation.
In the Palaeogene of East China Sea shelf, where typical soft-sediment deformation structures were developed, clastic deposits
of tidal-flat, delta and river facies are the main background deposits of Middle-Upper Eocene Pinghu Formation and Oligocene
Huagang Formation. This succession also records diagnostic marks of event deposits and basinal tectonic activities in the
form of seismites. 相似文献
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Dilce De FÁtima Rossetti Ana Maria GÓes Werner Truckenbrodt & JosÉ AnaisseJr 《Sedimentology》2000,47(2):309-323
Late Albian to Cenomanian upper shoreface deposits from the Grajaú Basin, northern Brazil, consist of well‐sorted, very fine‐ to fine‐grained sandstones with swaley, trough, tabular and minor hummocky cross‐stratification. A striking feature of these deposits is the abundance of large‐scale scour‐and‐fill structures, which consist of regularly spaced, repetitive, very shallow swales with either symmetrical or asymmetrical profiles, arranged along an undulose surface or as a succession of superimposed troughs. The sediment filling these scours is characterized by very fine‐grained sandstone with gently undulose, near‐parallel lamination to very low‐angle dipping cross‐stratification intergraded with swaley and hummocky cross‐stratification. The nature of the scours and the sedimentary structures of their fills reveal the action of combined flows, which are hydrodynamically similar to those developed during storms. However, it is speculated that the combined flows responsible for the genesis of these structures were formed by tsunami waves enhanced by tsunami‐induced ebb currents and/or tidal currents. This interpretation is proposed on the basis of several lines of reasoning: (1) palaeogeographic reconstructions of the study area during the late Cretaceous show that it was outside the belt favourable for the development of storms; (2) comparison of the scour‐and‐fill structures with stratigraphically correlatable deposits exposed north of the study area, where similar features occur in association with abundant seismically induced, soft‐sediment deformation structures; and (3) the presence of several styles of soft‐sediment deformation features (i.e. convolute lamination, bed collapse, large‐scale folds, massive bedding, sand‐filled fractures and diastasis cracks) are suggestive of synsedimentary seismic activity in Cretaceous deposits located in and near to the study area. This study proposes that episodic, high‐amplitude tsunami waves, enhanced by tsunami‐induced ebb currents, develop powerful flows capable of producing complex patterns of erosion and sedimentation, which may be represented by scour‐and‐fill structures similar to those described here. 相似文献
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鄂尔多斯盆地上三叠统延长组长4+5油层组湖泊三角洲前缘沉积中同生变形构造十分发育.通过对岩心观察及各种资料的综合分析,认为砂球、砂枕、球-枕构造、微断层递变层、微裂缝、液化卷曲变形等同生变形构造主要是由震积液化作用形成的.震积作用沉积可分为A、B、C、D、E等5个单元,分别组合形成ABCD型、BCD型或CD型、AB型、BCE型或BE型、BEBE型5种沉积序列类型,其中BCD型(CD型)和AB型最为发育.通过对古构造的分析,认为晚三叠世鄂尔多斯盆地拗陷中心的北西向基底"活化"及北西、北东向同生正断层的活动是导致该区古地震形成的主要原因. 相似文献
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在详细野外剖面工作的基础上,通过岩性特征、沉积构造及沉积序列等的系统观察研究,发现济源盆地下侏罗统鞍腰组重力流沉积由滑塌沉积、砂质碎屑流沉积和浊流沉积构成。滑塌沉积以砂岩和泥岩的混杂、岩层的滑动变形以及泥岩呈碎块被卷入砂岩层中为特征;砂质碎屑流沉积常呈厚层块状,颗粒分选和磨圆较差,杂基较多,可见漂浮于层内的石灰岩砾石;常见的浊流沉积分为2种类型: 具有明显正粒序结构的浊流沉积和砂泥岩薄互层的浊流沉积,可用鲍马序列来描述。鞍腰组重力流沉积可划分为3个沉积序列: 序列A记录了滑塌沉积→砂质碎屑流沉积→浊流沉积→深湖沉积的转换过程;序列B表现为砂质碎屑流与浊流沉积的叠覆;序列C由浊流及湖泊沉积构成,并经历了由序列A→序列B→序列C的沉积演化过程。重力流的形成受秦岭造山带于早侏罗世沿三门峡—鲁山—舞阳断裂发生逆冲推覆作用的控制,其沉积演化指示了秦岭造山带造山作用由强到弱的过程。 相似文献