Miocene tidal-influenced sedimentation to continental Pliocene sedimentation in the forebulge–backbulge depozones of the Beni–Mamore foreland Basin (northern Bolivia)

Mio-Pliocene deposits of the forebulge–backbulge depozones of the Beni-Mamore foreland Basin indicate tidally to fluvially dominated sedimentation. Seven facies assemblages have been recognized: FAA–FAG. FAA represents a distal bottom lake assemblage, FAB and FAD are interpreted as tidal flat deposits, FAC and FAG are interpreted as fluvial systems, FAE sediments are deposited in a subtidal/shoreface setting, and FAG represents a meandering fluvial system. The identification of stratigraphic surfaces (SU, MFS, and MRS) and the relationship among the facies assemblages permit the characterization of several systems tracts: a falling-stage systems tract (FSST) followed by a lowstand systems tract (LST), a transgressive systems tract (TST), and a highstand systems tract (HST). The FSST and LST may have been controlled by the uplift of the Beni-Mamore forebulge, whereas TST may result from a quiescent stage in the forebulge. Subaerial unconformity two (SU2) records the passage from a tide-influenced depositional system to a fully continental depositional system. The Miocene tidal-influenced deposits in the Beni–Mamore Basin suggest that it experienced a connection, either with the South Atlantic Ocean or the Caribbean Sea or both.     

The effects of differential subsidence and coastal topography on high-order transgressive-regressive cycles: Pliocene nearshore deposits of the Val d'Orcia Basin, Northern Apennines, Italy

This study focuses on the lowstand and early transgressive systems tracts of a basin-fill sequence of lower Pliocene nearshore deposits in the Val d'Orcia Basin of the Northern Apennines, Italy. The basin at that time was a semi-enclosed marine embayment, and, in the study area, its margin was subject to highly variable subsidence along the depositional strike, attributed to a decrease in tectonic displacement. The nearshore succession in the more rapidly-subsiding segment of the basin is around 20 m thick, comprising three storeys of laterally-stacked Gilbert-type delta lobes overlain by a shoal-water delta, whereas the nearshore succession in the adjacent, more slowly-subsiding segment, is up to 9 m thick. This succession is characterised by alternation of shoreface and offshore deposits, moderately wave-worked and covered by shoal-water deltaic facies.These coeval nearshore successions consist of several transgressive-regressive cyclothems. The development and lateral variation of the cyclothems was controlled by the local subsidence rate and coastal topographic gradient. Some of the cyclothems are considered to be higher-order sequences and others to be parasequences, with the former passing laterally into the latter in the area where the sea-level fall was countered by fast local subsidence. Some of the bounding surfaces are of limited lateral extent, with two parasequences passing laterally into a single one.Coastal topography controlled particularly the thickness of transgressive deposits. In the low-gradient setting of a delta plain, the relative sea-level rises caused major landward shifts of the shoreline and reduced fluvial sediment supply, with the formation of a transgressive lag in sediment-starved conditions. In the high-gradient coastal setting of the non-deltaic zone, the shoreline shift was minimal and had relatively little impact on local sediment supply, which promoted an accretionary transgression.At the end of the lowstand stage, the rate of sediment accumulation in the non-deltaic nearshore zone was lower, allowing the onset of subsequent transgression to be recorded considerably earlier than in the deltaic nearshore zone. This diachroneity suggests that facies criteria alone may not necessarily be a reliable basis for the recognition of systems tract boundaries.     

层序地层学在饶阳凹陷中的应用--以饶南地区为例

根据陆相地层层序在地震剖面、电测曲线上的识别标志以及岩石类型组合特点等特征，将饶阳凹陷饶南地区的下古近系划分出了3个二级层序、10个三级层序．其中三级层序Ⅷ、Ⅸ、Ⅹ为河流层序，可划分为基准面上升体系域和基准面下降体系域，其它均划分为3个体系域．针对研究区目的层段所划层序发育的特点，在层序地层单元划分和对比的基础上，结合构造发育史和地层厚度的变化反映出古地形特征，建立了该区的层序地层学模式，并初步探讨了层序地层学模式与含油气性的关系，对各三级层序的含油性做出了初步预测．     

层序地层学的发展与应用

层序地层学是在地襄地层学基础上发展起来的新的地学分支学科，为沉积地质学与地球物理学架设了新的桥梁。本文介绍了层序地层学的发展过程、基本原理、研究内容及应用情况。
        

浅谈“高分辨率层序地层学”概念的内涵

从“高分辨率层序地层学”概念的核心、科学要义与逻辑关系三方面着手,阐释了这种提法的科学性。指出,对这一概念的正确理解应是,高分辨率层序地层学是“高分辨率层序地层”之“学”,而不是“高分辨率”之“层序地层学”;相对于高分辨率层序地层学而言,经典的层序地层学可谓“低分辨率层序地层学”。     

琼东南盆地断陷期层序地层模式

琼东南盆地断陷期指示了从陆相向滨海环境演化的完整序列,因而断陷期层序的形成和演化既受幕式裂陷作用控制,又受区域海平面变化的影响。盆地断陷期代表一个巨层序(或构造层序),由3个层序组和6个层序组成,其中层序组分别对应于断陷期3次构造幕,层序则与全球三级海甲面旋回吻合。层序内部体系域特征与幕式构造作用的演化阶段有关,根据沉积环境差异可以划分为冲积平原型和滨海湖盆型两种层序模式。在裂陷作用阶段,幕式构造作用是断陷盆地内层序形成和演化的主导因素,区域海平面变化仅相对加强或减弱构造作用的影响;而在裂后热沉降作用阶段,随着构造沉降作用减弱,海平面变化影响更显著,其层序样式与陆表海环境的层序相似。     

准噶尔盆地腹部压性背景下“二元体系域”层序构型特征及其形成机理

在对野外露头、综合录井、地震资料、层序地层学分析研究的基础上,认为准噶尔盆地层序构型与传统层序模型强调的\"三元体系域\"不同,具有典型的\"二元体系域\"特征(低位粗碎屑体系域和湖扩超覆细碎屑体系域),结合准噶尔盆地构造演化及沉积充填过程,认为多幕逆冲挤压和松弛后稳定沉降相互耦合的作用过程是构成\"二元体系域\"的主要机制,形成过程可以划分为平静期、活动期和萎缩期3个阶段。在此基础上,建立了盆地斜列型砂体预测模型和削截尖灭型砂体预测模型。     

Facies and sequence stratigraphy of a Late Barremian wave-dominated deltaic deposit, Agadir Basin, Morocco

The late Barremian succession in the Agadir Basin of the Moroccan Western High Atlas represents wave-dominated deltaic deposits. The succession is represented by stacked thickening and coarsening upwards parasequences 5–15 m thick formed during fifth- or fourth-order regression and building a third-order highstand systems tract. Vertical facies transitions in parasequences reflect flooding followed by shoaling of diverse shelf environments ranging from offshore transition interbedded mudstones, siltstones and thin sandstones, lower shoreface/lower delta front hummocky bedforms to upper shoreface/upper delta front cross-bedded sandstones. The regional configuration reflects the progradation of wave-dominated deltas over an offshore setting. The maximum sea-level fall led to the development of a sequence boundary that is an unconformity. The subsequent early Aptian relative sea-level rise contributes to the development of an extensive conglomerate lagged transgressive surface of erosion. The latter and the sequence boundary are amalgamated forming a composite surface.     

湘西北上震旦统碳酸盐层序地层

碳酸盐层序地层应考虑碳酸盐＂加工厂＂、气候条件、构造背景、沉降速率、与陆地连接情况和底质类型等多种因素。碳酸盐层序地层模式在大多数情况下有别于Ｖａｉｌ的碎屑岩层序地层模式，并且气候条件是一个值得多加考虑的因素。通过不同相区碳酸盐层序地层的划分，笔者建立了研究区上震旦统碳酸盐层序地层模式，即陵山沱期为缓坡背景碳酸盐层序地层模式，灯影期为碳酸盐台地（初始）背景层序地层模式。在高水位体系域中识别出早期高水位体系域和晚期高水位体系域。已识别出浅潮下和环潮坪两种不同类型的副层序旋回。通过层序地层分析，笔者认为陡山沱底部的白云岩属于低水位楔。     

准噶尔盆地腹部压性背景下\"二元体系域\"层序构型特征及其形成机理

在对野外露头、综合录井、地震资料、层序地层学分析研究的基础上,认为准噶尔盆地层序构型与传统层序模型强调的“三元体系域”不同,具有典型的“二元体系域”特征（低位粗碎屑体系域和湖扩超覆细碎屑体系域）,结合准噶尔盆地构造演化及沉积充填过程,认为多幕逆冲挤压和松弛后稳定沉降相互耦合的作用过程是构成“二元体系域”的主要机制,形成过程可以划分为平静期、活动期和萎缩期3个阶段。在此基础上,建立了盆地斜列型砂体预测模型和削截尖灭型砂体预测模型。     

鄂尔多斯盆地北部下奥陶统层序地层学研究

以露头剖面、钻井岩心为研究对象,结合测井地质特征,对鄂尔多斯盆地北部下奥陶统层序界面特征及其成因类型进行了深入研究。将下奥陶统划分为10个三级层序,其中冶里组两个(SQ1,SQ2),亮甲山组两个(SQ3,SQ4),马家沟组一段至马家沟组六段各划分出一个(SQ5—SQ10)。层序SQ1—SQ4都表现为向上变浅的结构特征;层序SQ5—SQ7反映了区域上的海侵过程,总体为潮下环境,以加积序列为特征;层序SQ8反映了区域上的最大海浸,以大量凝缩段沉积为特征。由于加里东运动影响,层序SQ9—SQ10仅在研究区西缘和东南缘出露,西缘以盆地相深水沉积为特征,东南缘以发育潮坪相沉积为特征。     

歧北凹陷沙河街组层序地层学研究

本文从地震、古生物、沉积和测井等多方面的资料入手,用层序地层学方法研究了黄骅坳陷歧北凹陷沙河街组的地层层序,将其划分为两个大层序,即层序Ⅰ（沙三段）和层序Ⅱ（沙二、沙一段）。在每个层序中,又进一步划分出低位、湖进和高位三个体系域,总结了各个体系域的特征,进而指出有利的油气聚集相带和地段。     

岩石的磁性组构及其在岩石变形分析中的应用

文本总结了对采自巴彦乌拉山韧性剪切带的部分标本进行岩石组构数据测定的分析结果,并将其与用常规应变分析方法所得结果予以比较,表明了岩石磁化率各向异性椭球体能够反映总的应变椭球体,证明岩石磁化率各向异性技术做为一种岩石组构因素的研究是有发展前景的。岩石磁性组构资料可应用于变形岩石的应变分析,特别是在通常的岩石组构分析技术太费时间和粗糙的情况下更显示了其优越性。     

新疆库鲁克塔格地区新元古代层序地层学研究及对比

新疆库鲁克塔格地区上元古界可分为五个沉积层序,由下到上分别对应于贝义西组、照壁山组、阿勒通沟组、特瑞爱肯组至水泉组和汉格尔乔克组。第1层序由贝义西组构成,发育由粗碎屑斜坡扇和低水位楔构成的低水位体系域,向上逐渐变为粉砂岩、泥岩的海进体系域,并以向上变粗的退积准层序的高水位体系域结束,反映陆缘发展初期海平面的升降变化。第2层序由照壁山组构成,底部为粗粒石英砂岩,向上变为细粒砂岩、页岩互层,上部出现厚约30m的泥岩,顶部为紫红色砂岩,代表了由低水位经快速海进到高水位的变化过程,整体为水体较浅的滨浅海沉积环境。第3层序由阿勒通沟组构成,为冰成杂砾岩、砂岩、页岩组合,顶部出现厚2～3m的白云岩,沉积主体为低水位体系域,顶部白云岩为海进体系域,缺失高水位体系域。第4层序发育最为完整,特瑞爱肯组冰成杂砾岩为低水位体系域,冰成杂砾岩之上“盖帽碳酸盐岩”为海进体系域,扎摩克提组浊积岩、育肯沟组页岩、水泉组碳酸盐岩为高水位体系域,其中育肯沟组页岩为凝缩段沉积。第5层序低水位体系域由汉格尔乔克组冰成杂砾岩构成,顶部泥灰岩和白云岩为海进体系域,由于顶部被寒武系不整合覆盖,缺失高水位体系域。研究区上元古界层序基本可以和我国华南及印度Lesser Himalaya地区对比。     

延边地区渤海地块与兴凯地块之间古缝合带的初步研究

延边地区地处吉林省的东部。研究区南部为渤海地块,北部为兴凯地块,东部与朝鲜和俄罗斯相毗邻,西部与吉中地区以敦化－密山断裂为界。本文着重介绍延边地区渤海地块北缘及兴凯地块南缘的大陆增生历史和这两个古板块之间的古板块缝合带的地质特征。     

西天山科克苏河一带中新元古代碳酸盐岩沉积环境

新疆特克斯县科克苏河一带中—新元古代地层碳酸盐岩极为发育,但研究程度低,长期以来以群代组。通过1∶5万区调工作对本区基本层序调查和相分析,将该套地层解体。指出中—新元古代地层碳酸盐岩形成于“构造碳酸盐台地”的沉积环境,同时对角砾状灰岩的成因进行了探讨。     

江西广丰地区中奥陶统层序地层分析

本文通过对广丰县周家坞中奥陶统露头剖面层序、体系域、副层序的研究，识别出了三个不同性质的Ⅱ型层序界面和二个三级层序，确认这三个层序界面为符合实际又易于野外识别的自然界面，并对ＳＱ２中反映最大海泛期的高分辨异旋回驱动机制事件，提出可能受米兰柯维奇频率的春分点和秋分点间约２万年间隔的控制。