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1.
东营凹陷在沙河街组沉积期为北陡南缓的箕状断陷湖盆。通过钻井岩心、测井、薄片及扫描电镜分析,在断陷湖盆的南缓坡带古近系沙河街组中识别出了冲积扇、河流、三角洲和湖？白沉积体系,以及滨浅湖砂坝和缓坡远端浊积扇沉积相。建立了东营凹陷南部缓坡带层序地层格架及层序演化模式。在此基础上,详细研究了层序地层格架内的成岩作用特征。层序地层格架内主要成岩作用类型有压实作用、压溶作用、溶解作用等,成岩阶段为早成岩A、B期,晚成岩A、B期。层序地层格架内发育了碳酸盐胶结、石英次生加大、高岭石胶结和泥岩压实四种成岩相。 相似文献
2.
RICARDO NÉSTOR MELCHOR 《Sedimentology》2007,54(6):1417-1446
Well‐exposed Triassic rift strata from the Ischigualasto–Villa Unión Basin (NW Argentina) include a 80 to ca 515 m thick lacustrine‐dominated package that can be correlated across a half‐graben using key stratigraphic surfaces (sequence boundaries, lacustrine flooding surfaces and forced regressive surfaces). The characteristics of the synrift lacustrine fill in different parts of the half‐graben have been examined and the mechanisms controlling sedimentation inferred. A variety of sedimentary environments are recognized including; volcaniclastic floodplain, mildly saline lake and playa lake, offshore lacustrine, delta front to fluvial‐dominated and wave‐dominated deltas, distributary and fluvial channel, and interdistributary bay. The succession can be divided into four stratigraphic sequences (SS1 to SS4), the oldest of which (SS1) contains volcaniclastic, fluvial and saline lake deposits; it is thickest close to the western border fault zone, reflecting more rapid subsidence here. Accommodation exceeded sediment and water input during SS1. The second and third sequences (SS2 and SS3) mark the onset of widespread lacustrine sedimentation, reflecting a balance between accommodation creation and water and sediment fluxes. Sequences SS2 and SS3 are represented by offshore meromictic lacustrine and deltaic deposits, the latter mostly sourced from the flexural and southern axial margins of the half‐graben. The presence of stacked parasequences bound by lacustrine flooding surfaces is related to climatically induced lake‐level fluctuations superimposed on variable rates of subsidence on the controlling rift border fault zone. The youngest sequence (SS4) is represented by the deposits of littoral lacustrine and shallow shelf deltas distinguished by a change in lithofacies, palaeocurrents and sandstone composition, suggesting a switch in sediment supply to the footwall margin to the NW. The change in the sediment source is related to reduced footwall uplift, the possible presence of a relay ramp and/or supply from a captured antecedent drainage network. During SS4, the rate of creation of accommodation was exceeded by the sediment and water discharge. The stratigraphic evolution of lacustrine strata in the half‐graben was mainly controlled by tectonic processes, including subsidence rate and the growth and evolution of the border fault zone, but changing climate (inducing changes in water balance and lake level) and autocyclic processes (delta lobe switching) were also important. 相似文献
3.
中国东北晚中生代经历了区域性的裂谷期、后裂谷热沉降期和反转期。从西向东可以分成海拉尔—二连、孙吴—松辽、三江三个裂谷带。裂谷期形成了１００多个断陷,其中大多数是断面东倾的半地堑,从西向东倾角有从大变小的趋势。后裂谷仅中带发生了幅度巨大的沉降。裂谷期的变形作用及其裂谷期和后裂谷期的沉降特点表明裂谷区发生了区域性的单剪拆离伸展作用。反转期发生冲断褶皱作用,变形从东向西应变减小。 相似文献
4.
准噶尔盆地南缘前陆冲断带位于天山北麓,在晚新生代强烈的挤压作用下,地表发育数排背斜带。由于构造变形复杂、地震反射成像质量较差,对深层地质结构争议较大,另外前新生代盆地原型对晚新生代以来的褶皱冲断带构造格局的影响也尚未探讨。霍尔果斯—玛纳斯—吐谷鲁(简称霍-玛-吐)褶皱冲断带位于准噶尔盆地南缘前陆冲断带地表第二排背斜带,利用最新采集和处理的地震反射资料,并结合地表地质露头建立深层构造模型;利用平衡地质剖面复原和构造物理模拟实验的方法探索早侏罗世盆地原型结构对现今褶皱冲断带构造格局的影响;在此基础上分析霍-玛-吐褶皱冲断带深层天然气富集规律。霍-玛-吐褶皱冲断带垂向上发育古近系—第四系逆冲推覆构造、中上侏罗统—白垩系构造楔和下侏罗统半地堑断陷结构。控制早侏罗世半地堑系统的高角度正断层在晚期挤压构造变形体系中充当逆断坡,并控制上覆构造楔和浅层逆冲推覆构造的发育。早侏罗世半地堑系统具有分段性,并通过侧向断坡进行连接,侧向断坡上覆地层发育南北向走滑调节断层。油气勘探现状表明,霍-玛-吐褶皱冲断带内部南北向走滑调节断层具有高效沟通下侏罗统烃源岩的特点,是控制天然气的富集的重要因素。以上研究表明,中西部陆内前陆冲断带前新生代古构造对于晚新生代挤压冲断构造格局和深层天然气富集规律具有重要意义。 相似文献
5.
运用平衡剖面分析和构造物理模拟实验方法研究了典型铲式正断层模型上盘盆地的发育过程．研究表明，铲式正断层的产状以及断层上盘的变形方式直接影响上盘盆地的形态和沉积层序结构．简单铲式正断层的上盘发育相对简单的半地堑盆地，复杂铲式（坡坪式）正断层的上盘则发育包含有内部次级背斜凸起和向斜凹陷的复式半地堑，而且半地堑盆地的宽度与拆离断层面深度成正比．在沉积物补偿充填的情况下，渐进伸展将使半地堑的宽度也保持不变，从而使半地堑构造斜坡上产生“视水退”的层序结构现象，并且使盆地中“垂向加积”的沉积层序演变为宏观上“侧向加积”的沉积层序．这种由构造因素对半地堑盆地的层序充填的影响在渤海湾盆地的部分老第三纪断陷中得到印证． 相似文献
6.
箕状断陷盆地缓坡带层序格架特征与演化--以济阳坳陷为例 总被引：3，自引：0，他引：3
彭传圣 《华东地质学院学报》2005,28(3):239-243
依据缓坡带对层序类型、地层结构特征的控制及地貌特征、成因将济阳坳陷缓坡带分为单断-沉积坡折型、单断-斜坡型和双断-构造坡折型三种类型.三种缓坡类型构造-沉积演化背景不同,形成了不同的层序格架特征.济阳断陷盆地的构造演化史决定了较完整的缓坡带层序演化由双断-构造坡折型向单断-沉积坡折型再向单断-斜坡型演化. 相似文献
7.
李奋其 《沉积与特提斯地质》2003,23(2):35-42
酒泉早白垩世半地堑断陷呈南北向或北东向展布，进一步分为多米诺骨牌式、对倾式和背倾式三种。其充填物明显地受近南北向或北东向正断裂控制，其中的火山岩均为碱性玄武岩，可能由地幔熔融形成。初步认为，酒泉半地堑断陷是早白垩世陆内地幔热隆诱发的近南北向伸展构造。在新生代，由于印度板块的挤压作用，北祁连山前展式北向推覆作用可能使早白垩世半地堑断陷的南部地区转换成山脉，现今的半地堑南部边界被掩伏于北祁连山之下；同时，印度板块的挤压作用使控制半地堑沉积体系的近南北向或北东向正断裂转换为逆冲断裂．发生反转。 相似文献
8.
羌塘盆地中部隆起的演化及其在油气勘探中的意义 总被引：9，自引：0，他引：9
本文从沉积演化的角度分析了羌塘盆地中西部“冈玛错－西雅尔岗”隆起的演化过程，隆起在晚二叠世处于雏型发育阶段，晚三叠世肖茶卡－中株罗世雀昏时期为定型阶段，白垩纪－新生代为变形改造阶段。每一阶段隆起都控制着不同形式的生储盖组合的发育。隆起周缘具半地堑结构的凹陷是良好的油气聚集带之一。近隆起带北侧的构造层变形强度不大，对油气的后期保存比较有利。 相似文献
9.
施力方式对半地堑反转构造变形特征影响的物理模拟实验研究 总被引：13，自引：5，他引：8
根据断层的上下盘施力方式的不同设计了两组实验,以探讨在刚性边界条件下的半地堑反转构造的变形特点。实验结果表明(1)在自由边界基底驱动下形成的盆地反转规模较大,刚性边界处会沿原断层发生反转,而在自由端断层不会反转,但会形成深部低角度逆冲滑脱断层;(2)在刚性下盘侧向驱动下很小的挤压量就会形成盆地的反转,但是反转的范围较小,随着原设边界断层的角度由小到大,盆地内的断层会发生由刚性边界处单侧发生反转到两侧边界断层发生近对称式反转的变化;(3)实验结果证实了辽河坳陷西部凹陷反转构造是在刚性下盘为主动盘挤压变形下形成的。 相似文献
10.
Carbonate deposits, which unconformably overlie the Palaeozoic bedrocks, extensively occur in the base of the Tertiary lake succession in the half‐graben Shulu Sag, central Hebei Province, North China. This study focuses on the basal carbonate successions on the hinged western slope. Based on seismic, borehole and core data, nine facies are identified in the carbonate successions, and are further grouped into five facies associations: mid‐proximal alluvial fan, distal alluvial fan, fan fringe, moderately deep lake and deep lake. The first two facies associations constitute alluvial fans formed by debrisflows at the edge of lake and are dominated by mounded‐ to lobate‐shaped, matrix‐ to clast‐supported carbonate rudstones with minor calcretes in the lowermost rudstone units and basinward increase in interfingering with lacustrine carbonate facies. The fan fringe, moderately deep lake and deep lake associations are dominated by pebbly carbonate arenites (or rare carbonate arenites), calcisiltite‐calcilutites, and varve‐like calcilutites, calcareous shales and oil shales, respectively. Widespread occurrences of fine‐grained limestone packages containing varve‐like organic‐rich laminations, minor authigenic glauconite and pyrite, and planktonic and plant fossils suggest a meromictic, anoxic deep lake under a semi‐humid to humid climate, probably with a connection to marine basins. Similarities in lithology and fossil assemblages (e.g. trilobites) of lithoclasts with those of the Mid‐Upper Cambro‐Ordovician bedrock carbonates suggest that the clastic and dissolved carbonate loads were sourced from this Lower Palaeozoic catchment, and shed off the surrounding highlands into the basin. These carbonate facies associations represent the lake lowstand and transgressive deposits of the basal third‐order sequence (Ia) in which the highstand deposits are composed of lacustrine siliciclastics. During the lake lowstand stage (or initiation of basin‐filling) under an intermediate climate, carbonate alluvial fans occurred mostly subaerially at the bottom of the hinged slope with a narrow, shallow lake zone basinwards, and locally were perched within the palaeovalley on the mid‐upper slope. During the transgressive (deepening) stage under a semi‐humid to humid climate, carbonate alluvial fans became smaller in size and episodically stepped backwards upon the slope, with greatly expanded and deepened lake. Nevertheless, the carbonate system was switched to an exclusively siliciclastic system during the highstand stage. The exhumation and erosion of the Mid‐Lower Cambrian bedrock dominated by siliciclastics was probably the cause due to further uplift of the drainage basin. All these facts indicate that the carbonate deposition in the Shulu Sag was mostly controlled by the interactions of tectonics, climate and provenance. 相似文献