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1.
《海相油气地质》2021,(3)
为探究珠江口盆地开平凹陷构造沉降特征以及主控因素,以2条地震剖面的最新解释成果为基础,在地震剖面上共选取43个虚拟井进行构造沉降史计算,并进行综合分析。结果表明:(1)开平凹陷裂陷期(49～30 Ma)构造沉降量较大,各洼陷构造沉降差异性较大;裂后期(30 Ma至今)构造沉降量相对较小,各洼陷构造沉降差异性较小;(2)开平凹陷文昌组沉积期(裂陷一幕,49～39 Ma)为最大构造沉降期,恩平组沉积期(裂陷二幕,39～30 Ma)构造沉降速率显著减小,漂移期(30～17.5 Ma)和新构造运动期(17.5 Ma之后)构造沉降量均出现了不同程度的增大;(3)差异性沉降是开平凹陷的一个基本特征,多期次构造运动和拆离断层分段性、差异性活动是主控因素。 相似文献
2.
南海的形成演化受控于印-澳、欧亚以及太平洋板块的相互运动,为研究汇聚背景下板块碰撞及其远程效应提供重要窗口。为了揭示该汇聚背景下的多幕裂陷过程,本文选取地质信息丰富的整个珠江口盆地为典型区,利用三条高精度地震剖面,对盆地各地质单元进行断层活动速率和构造沉降速率的定量计算及综合分析。结果表明盆地裂陷期东部、中部和西部主要控凹断层的平均活动速率分别为96 m/Ma、223 m/Ma和124 m/Ma,且其平均沉降速率依次为8.5 m/Ma、34 m/Ma和12.7 m/Ma,盆地整体呈现中部裂陷作用最强,其后向西部和东部逐渐减弱的特征。本文认为这与先存断裂以及初始地壳厚度有关:盆地东部和中部存在NE向先存断裂,并且东部先存断裂更加活跃,因此在新生代拉伸应力下东部更易表现为裂陷作用最强的区域,其次为中部和西部;而受前新生代时期俯冲作用的影响,岩浆的底垫作用引起盆地东部地壳增厚,东部裂陷作用强度急剧降低,造成裂陷作用强度的东西差异。此外,盆地南段凹陷裂陷期的断层活动和沉降速率发生激增,裂陷作用存在向南迁移的现象。本文推测在深度相关的伸展模式的影响下,南段凹陷地壳温度升高,强度减弱,因而在伸展应力下发生快速的拉伸减薄,导致裂陷中心向南迁移及岩浆物质上涌。同时,侵入的岩浆物质导致高角度正断层转换成低角度正断层,进一步促进裂陷中心向南迁移。 相似文献
3.
珠江口盆地白云凹陷新生代构造演化动力学 总被引：42，自引：0，他引：42
白云凹陷构造演化史的研究对在白云凹陷开展油气勘探和深水沉积研究具有重要的意义。通过对断裂与沉积结构平面和剖面特点的分析,结合岩浆活动特点,文中提出白云凹陷是一个复式地堑,推测这种结构特点与凹陷下地壳的强烈韧性减薄和颈缩变形有关,表现为热岩石圈的伸展。其发育机制推测与白云凹陷位于构造转换带上有关,特殊的构造位置使白云凹陷成为强烈构造变形区,岩石圈地壳强烈减薄,伴随伸展过程和地幔上涌,脆性地壳或上地幔中部分熔融物质的出现导致岩石圈强度的急剧降低,在区域伸展应力场下以韧性流变方式减薄。岩浆在构造转换带下聚集并发育主岩浆房,由于白云凹陷南北边缘没有发育正断裂系统,岩浆主要沿垂直伸展的方向运移,因此在珠琼运动一幕和二幕南南东向伸展应力作用下,岩浆向白云凹陷的东部和西部运移至北西向基底深大断裂处,那里由于北西向断裂表现为左行张剪性质而成为压力较低的地区,从而成为岩浆上涌和侵位的地方。在岩浆聚集的地区,活动岩浆体附近的脆性变形被分散的韧性变形所取代,因此在凹陷的东北和西南两个角上,发育了张性和张剪性小断裂群,由于热岩石圈弹性较差,白云凹陷长期持续沉降。白云凹陷的断裂活动和沉积演化史还受到南海海盆扩张活动的影响。 相似文献
4.
西江凹陷和陆丰凹陷均位于南海北部珠江口盆地珠一坳陷,前者盆地结构为两条NE向铲式边界断层控制的近对称地堑,后者表现为6条弯曲主干断层控制的“两洼夹一隆”构造格局。文章运用三维地震资料,在盆地结构、断裂系统描述的基础上,选取了两个凹陷共8条地震—地质剖面进行平衡剖面恢复,计算两幕裂陷阶段盆地伸展量、拆离深度等定量参数,并据此分析二者差异裂陷演化过程及与区域构造演化之间的联系。两个凹陷在新生代均经历裂陷一幕、二幕以及裂后拗陷阶段,其中每幕裂陷又可细分为早、晚两个亚幕。西江和陆丰凹陷的裂陷演化具有时空差异性。从裂陷一幕到二幕,二者伸展量都具有随时间减小的一般特征,其中西江凹陷的伸展量随时间持续减小,在裂陷二幕晚期仍具有较大伸展量,而陆丰凹陷在裂陷二幕早期伸展量略有升高,但在晚期伸展量急剧减小,其减弱程度远大于西江凹陷。两个凹陷的拆离深度都具有随时间逐渐加深的特征。在裂陷一幕早、晚亚幕,陆丰凹陷的拆离深度略大于西江凹陷。在裂陷二幕早、晚亚幕,西江凹陷的平均拆离深度由约8 km增长至9 km左右,而陆丰凹陷的平均拆离深度由约8 km跳跃式增长至约35 km。盆地的几何结构、断裂系统以及伸展量和拆离深度变化特征均反映陆丰凹陷在裂陷二幕晚期受热沉降作用或提前结束裂陷阶段,而西江凹陷在裂陷二幕之后结束裂陷作用。研究区的裂陷阶段自东向西逐渐结束可能受控于东北次海盆的扩张及南海的自东向西渐进式扩张。区域板块构造演化提供了珠江口盆地沿其轴向向SW方向伸展作用增强的差异伸展环境。该研究所揭示的盆地裂陷演化差异性对认识珠江口盆地的裂陷时限的时空分布和差异裂陷演化都具有重要的意义,也对认识南海北部大陆边缘裂陷过程提供重要的定量数据约束。 相似文献
5.
本文对穿过南海西南次海盆的逾1000 km的多道地震测线CFT剖面进行了地震界面特征的识别和地震层序的划分，分段分析了拆离断层对其减薄陆壳的拆离作用。结合前人研究成果，对南海西南次海盆地壳结构特征开展了分析，并总结了其构造特征。西南次海盆在发生陆缘张裂—海盆扩张、洋壳出现—扩张后稳定沉积这一系列过程中，可划分为4个阶段的沉积响应：A阶段(古新世之前)——前裂谷阶段，表现为地壳在拉张应力下产生小的断层；B阶段（始新世—早渐新世）——陆缘的裂谷阶段，地壳在拉张应力下拉张减薄，A阶段产生的断层出现了旋转，出现了大型掀斜的拆离断层，沉积物为同裂谷沉积，该阶段以产生了破裂不整合结束；C阶段（晚渐新世—早中新世）——海盆扩张阶段，海盆开始扩张，张应力从陆缘转移到了洋盆；D阶段（中中新世以来）——海盆扩张结束以后，以一套稳定沉积为特征。 相似文献
6.
南海北部深水区新生代盆地三层结构及其构造演化 总被引：6，自引：0，他引：6
位于陆壳与洋壳之上的大陆边缘记录了大陆裂解-大洋打开的全部过程,是研究地球动力学的重要场所.南海北部深水区盆地位于南海北部大陆边缘,新生代盆地表现为裂陷期盆地、裂后拗陷期盆地及裂后洋盆沉降期盆地3层结构.裂陷期盆地表现为一系列地堑及半地堑结构,拗陷盆地表现为中间厚两侧薄的“碟形”盆地特征,裂后拗陷期盆地表现为大陆坡局部加厚,向南海洋盆方向厚度逐渐减薄的“挠曲”盆地形态.南海北部深水区盆地经历了3期构造演化过程,盆地表现出不同的动力学机制.裂陷期盆地受地幔物质上涌影响表现为水平伸展作用为主,盆地内普遍发育伸展构造样式,裂后拗陷期盆地表现为区域均匀沉降特征.而裂后洋盆沉积期受南海强烈沉降作用的影响表现出明显的向南海洋盆倾斜特征.大陆架-陆坡-深海平原的构造格局主要形成于裂后洋盆沉降期.南海及其北部盆地下伏地幔物质活动的差异性决定了盆地内的3层结构的形成演化过程. 相似文献
7.
珠江口盆地新生代发育跨越浅水区至深水区、多类型的拆离断陷,其中浅水陆架区拆离断陷是探究拆离构造变形与沉积充填响应的重要窗口.基于地震资料和钻井资料详细解析,对恩平凹陷低角度拆离断层特征进行了研究,探讨了拆离构造变形的控制因素、变形过程和沉积充填响应机制.研究表明,恩平凹陷低角度边界正断层为壳间拆离断层,长度约50 km,倾角平均17.5°,断面最深达中下地壳,裂陷期经历了中低角度到低角度的转变.拆离断层形成于中生代先存逆冲断层基础之上,与中下地壳韧性剪切穹隆和边界调节性走滑断裂相伴生,联合控制形成均衡深拆离、前展式宽拆离和迁移型复式拆离3种凹陷结构类型.垂向上可划分出三期裂陷幕,因差异构造变形而具有不同的沉积充填响应:（1）早文昌期均一裂陷幕,快速的裂陷沉降发育于先存逆冲断层弱面,形成具厚层中深湖的均一窄深箕状半地堑;（2）晚文昌期拆离伸展幕,凹陷受差异构造变形而发育成东、西沉积充填差异化的宽浅断陷,西部韧性剪切穹隆弱隆升与边界走滑断层强走滑控制了恩平17洼自迁移型中深湖和大型辫状河三角洲-重力流沉积,而东部韧性剪切穹隆强隆升控制了恩平12-18洼沉积中心跳跃式异迁移的沉积充填,过渡带发育大型走向斜坡扇三角洲;（3）恩平期拆离-断拗联控幕,构造变形由简单剪切向纯剪切转变,沉积向外流水系主导的浅水辫状河三角洲-浅湖相充填转变.低角度拆离断陷具有与高角度脆性断陷不同的构造变形和沉积充填响应,烃源岩与砂岩储层的时空分布非均质性强.研究成果对恩平凹陷的烃源岩和深部储层预测,以及南海北部陆缘同类拆离断陷的构造-沉积充填研究具有良好的指导意义. 相似文献
8.
靖海凹陷为南海北部深水区油气勘探的重点盆地之一,系统深入研究盆地结构特征及演化过程有助于深化对南海北部深水盆地的认识,为深水油气勘探提供新思路。本次研究以靖海凹陷2D地震资料的地质构造解释为基础,描述新发现的拆离断层的几何学特征,对比靖海凹陷东、西部结构样式差异性;通过沉降史模拟结果和典型拆离断层生长发育过程分析,恢复了靖海凹陷自新生代以来的沉降和构造演化过程;结合研究区深部资料与国外深水盆地最新研究进展,探讨了盆地结构和构造演化过程与南海北部陆缘地壳和岩石圈的伸展、减薄以及破裂作用的关系。研究结果表明,靖海凹陷东部与西部的盆地结构样式存在差异性,西部发育大型拆离断层及其所控制的拆离盆地系统,东部则呈现为由多个简单的南断北超的半地堑盆地所构成的复式地堑结构。盆地的构造演化划分为断陷期和坳陷期,其中断陷又可细分为断陷Ⅰ幕和断陷Ⅱ幕。盆地断陷Ⅰ幕对应于南海北部陆缘伸展阶段,高角度断层普遍发育;盆地断陷Ⅱ幕对应于南海北部陆缘减薄阶段—剥露阶段,拆离断层发育;当南海北部岩石圈完全破裂之后,盆地进入到坳陷期。 相似文献
9.
采用全盆地十条控制性综合地震剖面，结合钻井及虚拟井数据，利用几何量取，压实校正，均衡补偿，平衡剖面第一系列方法原理，建立了求取拉张量，构造沉降幅度，滑脱深度的几何模型，对东濮凹陷构造运动学特征进行了系统研究，计算了盆地基底拉张量，伸展系数和下第三系各层段的拉张量，各地质时期的构造沉降量及兰聊断层的滑脱深度；由此分析了凹陷南北不同构造部位基底拉和活动的差异和凹陷的幕式张裂活动特征及兰聊断裂的滑脱特征 相似文献
10.
为了探究渤海湾盆地新生代沉降过程与西太平洋板块俯冲过程的对应关系,作者收集整理27口钻孔和1条地震地质
剖面数据,并运用回剥技术和应变速率反演方法,模拟出渤海湾盆地中北部裂陷期地壳应变速率变化,分离出裂后期异常
沉降。模拟获得裂陷期地壳应变速率曲线具有明显的三次大的波动,可指示三次构造沉降事件：裂陷Ⅰ幕（60~42 Ma）,对
应于渤海湾盆地孔店组-沙四段沉积过程,平均构造沉降速率为4.6 m/Ma;裂陷Ⅱ幕（42~36 Ma）,对应沙三段-沙二段沉
积过程,平均构造沉降速率为5.5~30.5 m/Ma;裂陷Ⅲ幕（36~24.6 Ma）,对应于沙一段-东营组沉积过程,平均构造沉降速
率为14.7~54.7 m/Ma。研究区内裂后期观测构造沉降与模拟的理论值存在明显的差异,即存在异常沉降。盆地北部异常沉
降值在100~200 m,中部渤海海域异常沉降值在500~700 m,裂后期异常沉降向海域增大。作者推测渤海湾盆地裂后异常沉
降主要是太平洋板块俯冲诱发的深部地幔物质流动导致向下拖拽力引起的。因此,渤海湾盆地中异常沉降可能是一种动力
沉降。 相似文献
11.
松辽盆地裂谷期前火山岩与裂谷盆地关系及动力学过程 总被引：11，自引：0，他引：11
松辽盆地存在裂谷期前火山岩,之后上地壳脆性伸展发育半地堑裂谷盆地。裂谷期前火山岩近水平展布于基底之上,裂谷期,沉则分布于半地暂内,两者属于不同构造层。 相似文献
12.
New models for evolution of magma-poor rifted margins based on a review of data and concepts from West Iberia and the Alps 总被引：3，自引：2，他引：1
Direct observation and extensive sampling in ancient margins exposed in the Alps, combined with drill-hole and geophysical data from the present-day Iberia margin, result in new concepts for the strain evolution and near-surface response to lithospheric rupturing at magma-poor rifted margins. This paper reviews data and tectonic concepts derived from these two margins and proposes that extension, leading to thinning and final rupturing of the continental lithosphere, is accommodated by three fault systems, each of them characterized by a specific temporal and spatial evolution during rifting of the margin, by its fault geometry, and its surface response. The data presented in this paper suggest that margin architecture and distribution of rift structures within the future margin are controlled first by inherited heterogeneities within the lithosphere leading to a contrasting behaviour of the future distal and proximal margins during an initial stage of rifting. The place of final break-up appears to be determined early in the evolution of the margin and occurs where the crust has been thinned during a first stage to less than 10 kilometres. During final break-up, the rheology of the extending lithosphere is controlled by the thermal structure related to the rise of the asthenosphere and by serpentinization and magmatic processes.Dedicated to Daniel Bernoulli who taught me to compare the geological record of oceans and orogens 相似文献
13.
中国边缘海域及其邻区的岩石层结构与构造分析 总被引：3，自引：0，他引：3
利用中国边缘海域近年的地震层析成像结果,根据速度异常和各向异性分析东海、黄海和南海北部的岩石层结构和构造,讨论中朝块体和扬子块体在黄海内部的拼合边界(黄海东部断裂带)、东海陆架盆地上地幔异常与岩石层形成演化、南海北部地壳底部高速层的成因及地幔活动等问题。分析表明,黄海东部与朝鲜半岛之间存在一个深部构造界限(大致对应于黄海东部断裂带),分界两侧Pn波速度各向异性存在明显差异,反映不同构造应力和断裂剪切运动作用下的岩石层地幔变形特征。东海陆架下方的低速异常揭示了张裂盆地形成时期的地幔活动痕迹,表明中、新生代期间发生过地幔上涌并造成岩石层减薄,菲律宾海板块向西俯冲引发的地幔活动对东海陆架岩石层的形成、演化产生明显的影响。南海北部岩石层厚度较大并且温度相对偏低,地幔异常仅限于局部地区,估计南海北部大陆边缘的地壳底部高速层形成于张裂发生之前,或者是地壳形成时期壳幔分异时的产物。南海中央海盆的扩张不仅导致地壳拉张,软流层物质上涌,而且也造成岩石层地幔减薄甚至缺失。 相似文献
14.
This paper presents an updated review of recent field/structural and petrologic/geochemical studies on orogenic peridotites from the Alpine–Apennine ophiolites (NW Italy). Results provide determinant constraints to the evolution of the lithospheric mantle during passive rifting of the fossil Ligurian Tethys oceanic basin.The pre-rift, spinel lherzolites precursors, preserved in the mantle section of the Ligurian ophiolites, were resident in the lithosphere along an intermediate geothermal gradient (T about 1000 °C, P compatible with spinel-peridotite facies). Passive rifting by far-field tectonic forces induced whole-lithosphere extension and thinning (the a-magmatic stage). After significant thinning of the lithosphere, the passively upwelling asthenosphere underwent decompression melting along the axial zone of extension. Silica-undersaturated melt fractions infiltrated via diffuse/focused porous-flow through the lithospheric mantle under extension (the magmatic stage) and underwent pyroxenes-dissolving/olivine-crystallizing interaction with the percolated host peridotite.Pyroxenes assimilation and olivine deposition modified the melt compositions into silica-saturated. These derivative liquids migrated to shallower, plagioclase-peridotite facies levels, where they stagnated and impregnated/refertilized the lithospheric mantle. Melt thermal advection by melt infiltration heated to temperatures higher than 1200 °C the lithospheric mantle column above the melting asthenosphere.The syn-rift magmatic and tectonic processes induced significant rheological softening/weakening that destabilized the lithospheric mantle of the Europe–Adria plate along the axial zone of extension. The presence of destabilized lithospheric mantle between the future continental margins played a determinant role in promoting the geodynamic evolution from pre-oceanic rifting to oceanic spreading.The active upwelling of hotter/deeper asthenosphere inside the destabilized axial zone promoted transition to active rifting, enhancing continent break-up. Asthenosphere underwent partial melting and formed aggregated MORB liquids that migrated inside high-porosity dunite channels. The MORB liquids formed olivine-gabbro intrusions and pillowed lava flows (the oceanic crustal rocks).This paper evidences the primary role of mantle destabilization by melt infiltration in the geodynamic evolution of the Ligurian Tethys rifting. 相似文献
15.
A two-dimensional numerical modelling that simulate the kinematic and thermal response of the lithosphere to thinning was used for the quantitative reconstruction of the late Neogene to Recent times tectonic and stratigraphic evolution of the North Sicily continental margin (southern Tyrrhenian Sea). The numerical study of the evolution of the North Sicily margin builds on the crustal image and kinematic interpretation of the margin obtained by Pepe et al. [Tectonics 19 (2000) 241] on the basis of seismic data and gravity modelling. Tectonic modeling indicate that different segments of the margin were undergoing different vertical movements, which are mainly expression of the rifting and thinning of the lithosphere occurred during tectonic evolution of the southern Tyrrhenian Sea. A prediction of the pre-rift basement topography and the Moho along the margin converges to a value of 6.5 km for the depth of necking and a temperature-dependent EET (500° isotherm). The model fails to reproduce the morphology of the Solunto High confirming its non-extensional origin. A polyphase evolution is required to reproduce the observed syn- and post-rift stratigraphy. During the first rifting stage (between 9 and 5 Ma), crustal thinning factors reach maximum values of 1.27 in the Cefalù basin. A similar value is predicted for the subcrustal thinning around 60 km NNE of the profile margin. Crustal thinning factors increase during the second rifting stage (from 4 to 2 Ma) and reach values of 2 and up to 3.5 in the Cefalù basin and in the continent–oceanic transition zone, respectively. Similarly, subcrustal lithospheric thinning factors reach values up to 2.5 in the distal sector of the margin. An uplift of more than 100 m is predicted for the North Sicily shelf and surrounding onshore areas during the post-rift stage. The evolution of thermal structure with time is very sensitive to the partial thinning factors describing the evolution of the thinning itself during time. The lithosphere preserved part of its strength during extension. The effective elastic thickness (EET) along the margin through time is 24 km at the onset of rifting and reaches values less to 8 km during the second rifting stage in the northeastern end of the margin. 相似文献
16.
被动陆缘洋陆转换带和岩石圈伸展破裂过程分析及其对南海陆缘深水盆地研究的启示 总被引：2，自引：0，他引：2
作为伸展陆壳和正常洋壳之间重要的过渡和衔接,洋陆转换带(ocean-continent transition,简写为OCT)蕴含有丰富的地壳岩石圈伸展破裂过程的信息。文中通过系统的资料调研,在总结OCT研究历史、现状和发展趋势的基础上,阐明了OCT的现代概念、类型及其识别标志;详细介绍了以OCT为基础而建立的被动陆缘地壳岩石圈结构构造单元划分方案、表层沉积盆地构造地层格架及重要的构造变革界面特征;分析了大型拆离断层在地壳岩石圈薄化、地幔剥露过程中的控制作用;揭示了陆缘变形集中、迁移和叠合的规律,建立了被动陆缘岩石圈伸展、薄化、剥露和裂解模式。最后,论文对比了国际非岩浆型被动大陆边缘与我国南海OCT的研究,介绍了南海OCT和陆缘深水超深水盆地研究的新发现,提出深入研究南海OCT将为南海陆缘构造演化、洋盆扩张过程和深水超深水盆地的成因机制研究提供新的启示。 相似文献
17.
Stress and strain during fault-controlled lithospheric extension—insights from numerical experiments
Two-dimensional finite element techniques are used to study the temporal evolution and spatial distribution of stress and strain during lithospheric extension. The thermomechanical model includes a pre-existing fault in the upper crust to account for the reactivation of older tectonic elements. The fault is described using contact elements which allow for independent meshing of hanging wall and foot wall as well as simulation of large differential displacements between the fault blocks. Numerical models are run for three different initial temperature distributions representing extension of weak, moderately strong and strong lithosphere and three different extension velocities. In spite of the simple geodynamic boundary conditions selected, i.e., wholesale extension at a constant rate, stress and strain vary substantially throughout the lithosphere. In particular, in case of the weak lithosphere model, lower crustal flow towards the locus of maximum upper crustal extension results in the formation of a lower crustal dome while maintaining a subhorizontal Moho relief. The core of the dome experiences hardly any internal deformation, although it is the part of the lower crust which is exhumed the most. Stress fields in the lower crustal dome vary significantly from the regional trend underlining mechanical decoupling of the lower crust from the rest of the lithosphere. These differences diminish if cooler temperatures and, hence, stronger rheologies are considered. Lithospheric strength also exerts a profound control on the basin architecture and the surface expressions of extension, i.e., rift flank uplift and basin subsidence. If the lower crust is sufficiently weak, its flow towards the region of extended upper crust can provide a threshold value for the maximum subsidence which can be achieved during the syn-rift stage. In spite of continuous regional extension, corresponding burial history plots show exponentially decreasing subsidence rates which would traditionally be interpreted in terms of lithospheric cooling during the post-rift stage. The models provide templates to genetically link the surface and sub-surface expressions of lithospheric extension, for which usually no contemporaneous observations are possible. In particular, they help to decipher the information on the physical state of the lithosphere at the time of extension which is stored in the architecture and subsidence record of sedimentary basins. 相似文献
18.
白垩-古近纪为华北克拉通东部断陷盆地的形成时期,通过运用盆地分析技术,本次工作得到了这一时期各盆地的各阶段构造沉降曲线及相应的构造沉降量和沉降速率。构造沉降分析表明,华北克拉通东部白垩-古近纪盆地的最强构造沉降峰期为古新世(孔店期),次构造沉降峰期为早白垩世早期(莱阳期)。其中早白垩世早期为华北克拉通东部、南部盆地的最强构造沉降峰期,古新世为克拉通内部渤海湾盆地区的最强构造沉降峰期,而其它时期盆地的构造沉降特征表现为构造沉降峰期前后的弱沉降过渡阶段。结合盆地的分布规律,盆地的主要构造沉降中心在白垩纪集中在华北克拉通的南缘和北缘,而在古近纪则迁移到克拉通内部渤海湾地区,即由华北克拉通边缘向内部迁移。伸展期盆地的演化经历了宽裂谷(莱阳期)→窄裂谷(大盛期)→宽裂谷(孔店期)→窄裂谷(东营期)的循环演化模式,揭示了岩石圈的温度和强度的变化。而这种构造沉降的时空变化更支持华北克拉通破坏以拆沉机制为主。 相似文献
19.
通过对南海西北次海盆新获得的地震资料进行综合解释和层序地层分析,揭示了海盆中的沉积对构造演化阶段的响应。始新世-早渐新世陆缘裂陷期,盆地以对称裂谷形式,发育地堑裂谷层序,沉积以近物源为特征,相变大,发育了冲积扇-扇三角洲-湖相沉积,沉积体系的配置受同沉积断裂控制明显,快速沉降和充分的物源供给决定了沉积体系的构成特征。晚渐新世海底扩张期,岩石圈破裂,陆缘进一步拉开并开始海底扩张,出现海相沉积,来自陆坡的陆架边缘三角洲越过陆坡进入海盆,在海盆内沉积了一套向海盆中部逐渐减薄的楔状地层,并伴有大量的火山碎屑沉积物。早-中新世以来热沉降期,随着构造沉降增大,相对海平面总体不断上升,进入深水盆地,形成陆架陆坡体系,大量的碎屑物质以重力流、深水底流等深水作用方式进入海盆;沉降晚期陆架-陆坡物源供应减弱,琼东南中央峡谷成为其主要的物质供应来源通道,在此期间二次海平面下降、回升的综合作用下,海盆内发育了多期以下切水道为特征的低水位域沉积体系。 相似文献