沉积物重力流研究进展

沉积物重力流的研究随着深海、深湖环境油气资源的勘探成为现阶段沉积学领域研究的重点课题之一。沉积重力流的分类与命名已不断的完善与细化,浊流与碎屑流成为沉积物重力流的研究重点,沉积学者依据其流态特征、流变学特征、流体浓度与支撑机理对两者进行区分。重力流的的研究手段从野外观察到室内水槽实验,再到区域地震识别。沉积模式从单一浊流形成的"浊积扇"到多种流体相作用的"深海扇"或"海底扇"转变。由于沉积物重力流的控制因素较多,因此在重力流的概念、分类与成因上依然存在许多争议。水槽实验的不断发展,成为沉积物重力流的研究的主要途径,但实验模拟依旧存在很多问题,需不断完善水槽实验的限定因素与控制参量。     

浊流及相关重力流沉积研究综述

本文首先介绍了浊流及相关重力流的有关概念,并对浊流沉积研究历史进行了简要回顾,概括了当前浊流沉积的研究现状;随后,总结了浊积岩的沉积特征并对其成因进行了扼要解释;最后,对浊流及相关重力流沉积研究中两个有争议的问题－浊积相的划分和浊积相模式的建立进行了探讨。     

浅谈沉积物重力流分类与深水沉积模式

从浊流理论创立到现在的60余年时间里,深水沉积学研究已经取得了长足进展.但由于水下过程的复杂性,对沉积物重力流及沉积模式的认识存在颇多分歧.本文在对深水沉积研究历史与进展进行回顾与总结的基础上,对重力流各种分类方案及相应沉积模式进行了对比分析,认为:①人们对深水沉积的认识经历了一个螺旋式上升旋回;Bouma序列成因存在多种解释;砂质碎屑流概念是对Bouma序列、扇模式的发展.②沉积物重力流分类必须遵循流变学和沉积物搬运机制的重力流分类方法.③Shanmugam新近建立的碎屑流主导斜坡模式解决了斜坡区的砂体成因分布问题(原来认为此处“过路不停”无砂质沉积).④地震沉积学的发展与应用必将促进人们对深水沉积的认识,从而建立更合理的深水沉积模式.     

浊流沉积研究综述和展望

浊流理论的建立具有划时代的意义。浊流沉积的研究已经进行了半个多世纪,从理论到实践都取得了巨大的进展。本文首先讨论了浊流及其相关的几个概念,同时概述了浊流沉积的国内外研究历史和进展,重点介绍了浊积岩的识别标志及其沉积序列,指出下一步研究的重点应放在陆相湖泊浊流沉积及其含矿性上。     

滇西南景谷—镇沅地区第三纪重力流沉积及其地质意义

本文通过详细的沉积学研究,讨论了滇西南景谷—镇沅地区第三纪重力流的沉积特征,包括碎屑流、颗粒流和浊流三种沉积类型。它们的发育直接受印度板块与欧亚板块碰撞及其后陆内变形的控制,是区域构造事件的响应。     

滇西南景谷-镇沅地区第三纪重力流沉积及其地质意义

本文通过详细的沉积学研究,讨论了滇西南景谷-镇沅地区第三纪重力流的沉积特征,包括碎屑流、颗粒流和浊流三种沉积类型。它们的发育直接受印度板块与欧亚板块碰撞及其后陆内变形的控制,是区域构造事件的响应。     

甘肃文县上震旦统重力流沉积及其构造古地理的意义

分布于甘肃文县一带的原“碧口群”据岩性、层位特征及微古植物化石厘定为震旦系,并可进一步划分出南沱组、陡山沱组、灯影组。在陡山沱组发育一套陆源浊积岩和深水相泥质岩、硅质岩组合,底部夹有多层火山碎屑岩及火山熔岩;灯影组发育碳酸盐岩浊积岩层和重力滑动层。这些浊积岩能够在地质记录中得以保存且厚度可达数百米,说明该区当时受到一个相对活动的从深水海沟演化到较浅水弧后盆地这一沉积构造环境的控制,从而说明扬子地台北缘应是具有拉张活动性质的被动大陆边缘。     

重力流沉积：理论研究与野外识别

重力流沉积是（半）深海和深湖环境中一种重要的沉积现象,因此准确识别重力流沉积对恢复古代沉积环境具有重要意义。从沉积物重力流的基本理论出发,介绍四类重力流沉积的特点和野外鉴别特征。碎屑流沉积表现为颗粒大小混杂,底面平坦,板条状砾石平行层面排列;超高密度流沉积的砂岩呈厚层状或块状,砂岩内部经常出现较大砾石或泥岩碎片,泄水构...     

深水重力流沉积研究进展

深水重力流沉积研究经历了半个多世纪发展,从浊流及鲍马序列开始,到把深水砂岩普遍解释为浊流成因以及海底扇模式的建立,再到今天学者们对鲍马序列的质疑,深水重力流沉积的研究经历了认识上的螺旋式上升旋回。目前关于深水重力流沉积争议的焦点在于高密度浊流是否属于浊流的范畴,深水砂岩是否都是浊流成因。以Shanmugam为代表的学者认为,绝大多数的深水砂岩都是碎屑流成因而非浊流成因,并且提出了重力流分类新方案,同时建立了与其匹配的深水斜坡沉积模式。通过对前人成果的广泛调研,经过对比总结,认为:1根据流变学和沉积物搬运机制,重力流分为碎屑流(砂质碎屑流和泥质碎屑流)、颗粒流、浊流;2浊流的韵律结构特征为明显的正粒序且没有漂浮的碎屑颗粒,碎屑流自下而上呈逆-正粒序的两套韵律变化且发育有漂浮的碎屑颗粒;3Walker的综合扇模式与Shanmugam的斜坡沉积模式,二者是可以共存的,只是在某一地区适用性不同而已。     

流体性质转换机制在重力流沉积体系分析中应用初探

自1950年Kuenen发表"浊流形成粒序层理"一文至今,深水重力流研究取得了长足发展。然而,目前很多学者不仅对浊流理论分歧很大,而且对浊流概念、术语的使用也有不同的观点,这严重制约了重力流的分类及重力流沉积体系的识别。本文在重力流沉积过程和流态研究的基础上,提出了基于"流体性质转换"理论的重力流沉积体系分析方法。研究认为,重力流在形成、发展和消亡过程中不仅存在多个流体阶段,而且存在着多种流态之间的转换。这种流体发育的最终阶段特征决定了重力流沉积体系的形态与类别,而流态共存与转换的特性造成了深水紊流成因的浊积岩与其他流体成因的岩相共存的沉积特征。根据这一理论对牵引流—碎屑流成因的扇三角洲体系、浊流成因的近岸水下扇体系和碎屑流成因的斜坡裙体系进行成因分析与特征对比,阐述了"流体性质转换"理论在沉积体系识别中的作用。     

Review on Subaqueous Sediment Gravity Flow and Submarine Fan

Subaqueous sediment gravity flow is the volumetrically most important process transporting sediment across our planet, which forms its largest sediment accumulations (submarine fan). Based on the previous studies, we tried to clear up the concept, classification and identification of subaqueous sediment gravity flow, and introduced the progress of modern direct observation and submarine fan model. Turbidity current and debris flow are two of the most important parts of the gravity flow, the former deposits layer by layer with normal gradation while the latter is en masse settling with chaotic disorder. The turbidity current transformed into the debris flow during the transportation is called hybrid flow. The hyperpycnal flow is the turbidity current formed by flood discharges into the ocean/lake. Modern direct observations show that the turbidity current can contain dense basal layers and last for a week. The structure of turbidity current can be different from those surge-like turbidity current observed in laboratory. Submarine fans are mainly composed of channel, levee, lobe, background deposits and mass transport deposits, which should be studied by architecture analysis and hierarchical classification. The channel deposits extend narrowly with abundant erosion structures; levee deposits are composed of thin layer mud-silty turbidites, wedge thinning laterally; the lobe deposits extend well laterally with narrow range of grain size. The hierarchy of channel deposits is channel unit, channel complex and channel complex system. The hierarchy of lobe deposits is bed, lobe element, lobe and lobe complex.     

松辽盆地北部青山口组重力流特征研究及其地质意义

为在陆相湖盆寻找有利勘探目标,在岩芯观察和沉积、构造分析的基础上,对岩芯观察资料、三维地震资料、钻井资料和测井曲线资料等进行了较为详细的研究。研究表明,松辽盆地北部青山口组发育广泛的湖相泥岩沉积,沉积相主要为三角洲平原、三角洲内前缘、三角洲外前缘、深湖-半深湖和滨湖。湖区发育大规模重力流沉积,该区发现的重力流沉积主要有滑动岩型、滑塌岩型、碎屑流型、浊积岩型等类型;重力流岩石学特征表明青山口组二段下部的重力流沉积,主要为滑动岩型和滑塌型,岩性主要以粉砂岩,泥质粉砂岩,粉砂质泥岩薄互层为特征,局部含油或有油迹;而青山口组一段顶部的重力流沉积,主要为碎屑流型和浊流型,岩性上以粗砂岩、粉砂岩、粉砂质泥岩、泥岩的薄互层为主。初步探讨了重力流的发育和控制机制,分析表明青山口组重力流沉积是湖区的有利储层区域,英台大安地区为最有利储层。该研究对深入了解湖相储层特征起指导作用。重力流沉积勘探在松辽盆地还处于探索阶段,其研究为在大型陆相湖盆中寻找新的有利勘探目标奠定坚实基础。在陆相湖盆中研究深水重力流沉积,对沉积学研究具有推动作用。     

Analysis of the Grain Size Properties and Flow Body Classes of the Mud Sand Flow: An Example of Liantanggang Collapsing Hill and Gully in Wuhua County of Guangdong

Mud sand flow is a kind of solid-liquid two-phase flow formed in collapsing hill and gully basin during rainfall. It is the main way to export erosion product. The discrimination of its fluid type is one of the collapsing hill and gully control theoretical basis. This paper analyzed the basic characteristics of mud sand flow like grain size and so on through fieldwork and sampling. The results show that the density of mud sand flow is between 1.16~1.60 t/m³ and the solids content is between 257.03~960.55 kg/m³, both of which decrease from the upper to the lower channel. The slurry of mud sand flow is composed mainly of silt and clay. As the density increases, the particle size distribution curve transforms from a single peak to the bimodal distribution similar to the weathering crust with no sorting, and the grain size of mud sand flow becomes coarser which shows a well positive linear correlation between the sediment median particle diameter and density of mud sand flow. The comparison during mud sand flow, hyperconcentrated flow and debris flow shows that collapsing hill and gully mud sand flow, which belongs to an intermediate class between hyperconcentrated flow and debris flow, has a closer link with debris flow. Therefore, mud sand flow can be considered as a sub-class of generalized debris flow that may be called as collapsing hill and gully type debris flow.     

Sustained turbidity currents and their interaction with debrite-related topography; Labuan Island, offshore NW Borneo, Malaysia

The Temburong Fm (Early Miocene), Labuan Island, offshore NW Borneo, was deposited in a lower-slope to proximal basin-floor setting, and provides an opportunity to study the deposits of sustained turbidity currents and their interaction with debrite-related topography. Two main gravity-flow facies are identified; (i) slump-derived debris-flow deposits (debrites) — characterised by ungraded silty mudstones in beds 1.5 to > 60 m thick which are rich in large (> 5 m) lithic clasts; and (ii) turbidity current deposits (turbidites) — characterised by medium-grained sandstone in beds up to 2 m thick, which contain structureless (T_a) intervals alternating with planar-parallel (T_b) and current-ripple (T_c) laminated intervals. Laterally discontinuous, cobble-mantled scours are also locally developed within turbidite beds. Based on these characteristics, these sandstones are interpreted to have been deposited by sustained turbidity currents. The cobble-mantled scours indicate either periods of intense turbidity current waxing or individual flow events. The sustained turbidity currents are interpreted to have been derived from retrogressive collapse of sand-rich mouth bars (breaching) or directly from river effluent (hyperpycnal flow). Analysis of the stratal architecture of the two facies indicates that routing of the turbidity currents was influenced by topographic relief developed at the top of the underlying debrite. In addition, turbidite beds are locally eroded at the base of an overlying debrite, possibly due to clast-related substrate ‘ploughing’ during the latter flow event. This study highlights the difficulty in constraining the origin of sustained turbidity currents in ancient sedimentary sequences. In addition, this study documents the importance large debrites may have in generating topography on submarine slopes and influencing routing of subsequent turbidity currents and the geometry of their associated deposits.     

鄂尔多斯盆地上三叠统延长组长7段深水重力流沉积类型

以鄂尔多斯盆地上三叠统延长组长7段取芯段为主要研究对象,以详细的岩芯观察为基础,以Z43井为例,研究鄂尔多斯盆地延长组长7段深水重力流沉积类型及其特征.研究结果表明,研究区主要发育砂质碎屑流沉积、低密度浊流沉积及混合事件层三种沉积类型.砂质碎屑流沉积整体呈块状,岩性为中—细砂岩,内部可见多个接触面,为多套砂质碎屑流沉积...