青海省贵南县过马营一带早中三叠世隆务河组沉积特征

青海贵南县过马营一带隆务河组为一套典型的浊流沉积,对此套浊积岩的沉积特征进行研究。通过对过马营一带隆务河组浊积岩的岩石组合特征、地层层序及鲍玛层序特征分析,探讨其沉积环境特征,并与典型浊积扇模式对比,建立沉积模型。综合分析认为,隆务河组由下向上的3个段分别位于浊积扇的外扇、中扇、内扇,其中中扇辫状河道发育。此研究对于西秦岭造山带的沉积环境分析及构造演化具有重要的意义。     

秦岭沉积岩容矿金矿类型控矿条件与找矿方向

秦岭地区沉岩包括扬子地台北缘志留纪裂陷沉积到晚古生代被动大陆边缘断陷－拗陷盆地沉积和二叠纪裂陷沉积。现有勘查资料表明秦岭地区沉积岩容矿金矿大多集中在泥盆系和三叠系,少量分布在志留系,石炭系和二叠系。     

西秦岭华力西—印支期幕式裂陷活动初探

华力西—印支期，西秦岭受古特提斯洋的影响发育三期裂陷活动（１、泥盆纪；２、石炭纪；３、二叠至三叠纪），造成该区地层展布星条带状，深水沉积与浅水沉积相间，以及活动型海槽沉积与稳定型浅海沉积相间的格局，是加里东期之后秦岭构造带东西分异的主要原因．     

渤中西环古近系东营组物源转换与沉积充填响应

通过砂岩中碎屑锆石U-Pb年龄分析、火山碎屑组分含量变化、地震多属性分析、层序地层格架与沉积充填特征综合分析,认为东二段沉积时期渤中西环的物源供给方式、层序地层格架及沉积充填特征发生明显的变化.东二下段沉积期前,湖盆处于强烈裂陷期,中-深湖相泥岩发育,物源主要为盆地内部的中生代火成岩基底,沉积层序明显受盆内低凸起控制,在盆内低凸起四周发育一系列近源的扇三角洲朵体;东二下段沉积期后,湖盆处于断-坳过渡期,盆内低凸起四周的断裂活动减弱,沉积层序逐渐向盆内低凸起超覆,盆外太古代-元古代变质岩物源供给不断加强,近源的扇三角洲砂体逐渐向远源的辫状河三角洲砂体转化,同时发育宽广的滨浅湖环境.渤中西环古近纪沉积充填过程中,地层样式、沉积模式与物源供给方式的一致性变化,体现了裂陷湖盆充填演化的内在规律,为我国东部裂陷盆地演化及裂陷旋回划分提供了新的线索.     

西秦岭造山带泥盆纪沉积地质学和动力沉积学研究:西秦岭中带泥盆纪小型克拉通盆地的沉积特征及盆地格局

秦岭微板块位于商丹－武山和勉略－巴山弧断裂之间。泥盆纪时期，微板块主体处于稳定的小型克拉通盆地背景。本文仅从西秦岭中带泥盆系入手，探讨该区泥盆系的沉积体系和盆地格局。小型克拉通盆地北带的西汉水小区以古岛屿滨岸－陆棚沉积体系（艾菲尔期）、碳酸盐台地－生物礁沉积体系（吉维特－弗拉斯期）、深水盆地和泥质浊积岩沉积体系（法门期）为特征。南带武都小区则以陆棚碎屑岩（艾菲尔期）和缓坡型台地－陆棚沉积体系（吉维特－法门期）为主，该小型克拉通，泥盆纪时期是一稳定块体，到二叠纪－三叠纪才受中秦岭裂陷槽分隔成两个块体。     

西秦岭造山带泥盆纪沉积地质学和动力沉积学研究:西秦岭南带泥盆纪裂陷槽盆地、摩天岭地体沉积特征和盆地格局

南秦岭裂陷槽位于中秦岭微板块和摩天岭地体之间．本文根据裂陷槽盆地三河回群和摩天岭地体泥盆系沉积学研究，结合火山作用和生物古地理的研究，探讨该区泥盆纪的盆地格局．三河口群以深水盆地和陆棚沉积为主，内夹拉斑玄武岩和硷性玄武岩，岩石化学和稀土元素的分配型式都反映其处于裂陷槽盆地背景。生物古地理分异也指示型陷槽盆地的存在．摩天岭地体泥盆系为滨岸－陆棚碎屑岩和陆棚－缓坡碳酸盐沉积，其为扬子板块北部大陆边缘的一部分．     

西秦岭北缘武山地区上白垩统沙漠相沉积特征

西秦岭广泛但不连续分布着一套晚白垩世红层地层。这套红层地层所代表的原型沉积盆地是西秦岭中生代陆内造山期发育的相互孤立的山间盆地拟或是整体统一红层盆地新生代以来地壳隆升侵蚀破坏的残留一直存在争议。这个争议问题即关乎到对西秦岭中生代末期的构造地貌状态的认识,也关乎到现今青藏高原东北缘新生代以来地壳隆升初始地质背景。通过对西秦岭北缘武山地区上白垩统红层沉积地层中发育的一套砖红色砂岩的沉积序列、沉积构造、粒度分布等宏观地质特征的较详细研究,结合对这套砂岩的矿物成分和显微结构以及石英颗粒SEM表面结构特征的研究,表明这套砖红色砂岩具有如下特征:1）发育典型的大型风成交错层理;2）粒度均匀,分选好,以中-细砂、极细砂组分为主,缺乏粉砂-黏土颗粒组分;3）石英颗粒磨圆度好,表面发育碟形和新月形坑、溶蚀坑、硅质薄膜等风成砂颗粒具有的独特表面特征。据此提出这套砖红色砂岩是典型的沙漠相沉积的新认识,并根据沙漠相沉积类型的识别标志将其分为沙丘沉积和丘间沉积两种沉积类型。秦岭北缘武山地区晚白垩世沙漠相沉积的存在,结合西秦岭腹地同时代的哈达铺、岷县西江等地分布在山顶面的晚白垩世红层地层中存在类似的沙漠相沉积分析,提出了西秦岭晚白垩世不仅处于干旱炎热气候环境,而且曾呈现出地形相对平缓的泛盆地构造地貌状态。这套红层沉积反映了西秦岭晚白垩世为统一红层沉积盆地而非孤立的山间盆地,现今多不连续分布在山顶面之上是新生代以来地壳不均匀隆升和侵蚀共同作用的结果。     

秦岭三叠系分带及印支期发展史

秦岭及共邻区的三叠系自北而南可分为四带.北秦岭三叠系具有富含植物化石的陆相上三叠统,其下的优地槽型细碧角斑岩系时代未定.中秦岭下三叠统为复理石夹多层砾状灰岩,后者系斜坡沉积,物源可能来自北方,安尼期为复理石.南秦岭北带在二叠纪晚期已裂陷接受复理石及以砾状灰岩为代表的斜坡沉积.早三叠世至安尼期为深水相黑色板岩、薄层灰岩、复理石并夹火山岩.南秦岭南带及巴顿喀喇从早三叠世至安尼期为扬子地台的一部分,岩相及化百群与之一致,具有发育良好的安尼期陆棚边缘生物滩.从拉丁期开始裂陷．出现鱼鳞蛤页岩、砾状灰岩及巨厚复理石,后者延续至晚三叠世,有放射虫为证.整个中,南秦岭呈现一个由二叠纪晚期开始,延续于印支期的裂陷槽发育史.它的北部—中秦岭和南秦岭北带于二叠纪末及三叠纪初先后裂陷,并于拉丁期褶皱回返.它的南部—南秦岭南带及巴颜喀喇于拉丁期裂陷,并于三叠纪末回返.这个裂陷槽是否构成印支期秦岭的主体,抑或它仅是“北秦岭小洋盆”在扬子大陆边缘的弧后扩张盆地,取决于北秦岭是否存在早、中三叠世优地槽沉积.后者尚未证实.     

川西炉霍二叠纪—三叠纪古裂谷的识别及其地质演化

本文根据边界断裂的控相特征、区内代表深成构造活动的层状堆晶基性－超基性岩的产出１、二叠纪－三叠纪海底拉斑玄武岩的喷溢活动特征、巨厚的浊积岩建造和混杂式建造的共生以及地球物理特征,认为松潘－甘孜地块内部存在炉霍海底裂谷。炉霍裂谷二叠纪－三叠纪经历了初始裂陷、沉积－拗陷、高度裂陷至萎缩消亡的４个阶段。裂谷封闭二叠纪－三叠纪经形成以Ⅰ型为主的中酸性侵入体,区域构造应力场经历了燕山早期近ＷＳＷ－ＥＮＥ向挤     

西秦岭海西-印支期裂陷活动及其与古特提斯的关系

海西-印支期，西秦岭地区受古特提斯洋的影响在前海西期变质基底之上发育三期裂陷活动（１．泥盆纪；２．石炭纪；３．二叠至三叠纪），造成该区地层展布呈条带状．深水沉积与浅水沉积相间，以及活动型海槽沉积与稳定型浅海沉积相间的格局．是加里东期之后秦岭构造带东西分异的主要原因。     

Coarse-grained submarine fan and slope apron deposits in a Cretaceous back-arc basin, Antarctica

The Cretaceous of west James Ross Island, Antarctica represents the proximal fill of a late Mesozoic back-arc basin that was probably initiated by oblique extension during the early development of the Weddell Sea. The succession records sedimentation in two contrasting depositional systems: a laterally persistent slope apron flanking the faulted basin margin interrupted both spatially and temporally by coarse-grained submarine fans. Slope apron deposits are dominated by thinly interbedded turbiditic sandstones and mudstones (mudstone association), interspersed with non-channelized chaotic boulder beds, intraformational slump sheets and isolated exotic blocks representing a spectrum of mass-flow processes from debris flow to submarine gliding. Localized sand-rich sequences (sandstone-breccia association) represent sandy debris lobes at the mouths of active slope chutes. The submarine fan sediments (conglomerate association) are typified by coarse conglomerates and pebbly sandstones, interpreted as the deposits of high-density turbidity currents and non-cohesive debris flows. Three assemblages are recognized and are suggested to represent components of the inner channelled zone of coarse-grained submarine fans, from major fan channels through ephemeral, marginal channels or terraces to levee or interchannel environments. The occurrence of both slope apron and submarine fan depositional systems during the Early and Mid-Cretaceous is attributed to localized input of coarse arc-derived sediment along a tectonically active basin margin. Periods of extensive fan development were probably linked to regional tectonic uplift and rejuvenation of the arc source region; cyclicity within individual fan sequences is attributed to migration or switching of fan channels or canyons. Slope apron sedimentation was controlled largely by intrabasinal tectonics. Local unconformities and packets of amalgamated slide sheets and debris flow deposits probably reflect episodic movement on basin margin faults. Differential subsidence across the basin margin anchored the basin slope for at least 20 Myr and precluded basinward progradation of shallow marine environments.     

Geology and Tectonics of the Songpan-Ganzi Fold Belt,Southwestern China

In the Late Paleozoic, the Sino-Korean (North China) and Yangtze-Cathaysian (South China) cratons collided. The Carboniferous and Permian foreland basin to the north of the Tongbo-Dabie Mountains, and elongate intermontane basins in East Qinling, were filled by marine to terrestrial sediments, in which the fauna and flora communicated from North China, South China, and West China. In Triassic time, the Dabie-Sulu Mountains became a Himalaya-type mountain range as a result of continent-continent collision and doubling of the crust. Marked exhumation of this mountain range shed huge amounts of detritus to the west. First filled were the remnant ocean basins in Qinling. As the remnant basins filled, submarine fan deposition shifted to the west to gradually fill the Songpan-Ganzi area. Songpan-Ganzi is surrounded by continents with pre-Sinian basement. The Sinian and Paleozoic strata and their fauna and flora are of Yangtzean affinity.

Beginning in the Permian, a midocean-ridge triple junction was developed in Songpan-Ganzi, and the new oceanic crust provided more space for submarine fans. Later, a Triassic subduction zone was developed along the western margin of Songpan-Ganzi, and the rising island arc provided a smaller amount of detritus to its backarc basin in the east, which became part of Songpan-Ganzi. During the Early and Middle Triassic, the Dabie-Sulu high mountain ranges blocked the monsoon from blowing to the north, and, therefore, typical redbeds were deposited in North China for at least 15 million years, whereas the deposits of the same age in South China are still shallow-marine and littoral facies with coal measures. In the Late Triassic and Jurassic, the Dabie-Sulu mountain range was leveled to low hilly country. The monsoon blew to the north very easily, and coal measures were deposited all over North China. In Songpan-Ganzi, the Triassic submarine fan deposits were folded and metamorphosed during latest Triassic time, and the Songpan-Ganzi fold belt was formed. The Cenozoic Himalaya and its relationship with submarine fans in the Indian Ocean is similar to the Triassic Dabie-Sulu mountain range and its relationship with the Songpan-Ganzi submarine fans. Huge submarine fans and ultrahigh-pressure metamorphism are consequences of continent-continent collision, but the involved continents should have considerable sizes.     

西藏荣玛地区尼俄玛山下二叠统曲地组沉积特征

西藏荣玛地区尼俄玛山下二叠统曲地组发育一套重力流沉积组合,根据其岩性、沉积构造和含化石特征等,在该套沉积体系识别出了9种岩石类型、5种岩石组合类型,并分别将其划归内扇主水道-水道间、中扇分支水道-天然堤-水道间、外扇朵叶体-末端水道及深水玄武岩和泥岩4种微相组合类型,以及海底扇和深海盆地2种沉积相类型,证明研究区曲地组属于半深海-深海沉积环境。这一结论与前人认为曲地组属于滨浅海相的认识完全不同,说明南羌塘盆地下二叠统曲地组在区域上存在明显的相变,即西部日土一带的滨浅海沉积向东到改则-尼玛一带逐渐变为半深海-深海沉积;证明南羌塘盆地早二叠世古特提斯洋进入演化成熟期,但羌塘地块从冈瓦纳北缘的裂解、脱离时间在东西向并不一致,东部早于西部;曲地组大套深水黑色泥页岩及砂岩为代表的重力流沉积的广泛发育,说明其具有重要的油气地质意义。     

濮城油田沙三中亚段水下扇的特征

濮城油田沙三中亚段为水下扇沉积，具牵引流和重力流的双重特征。沉积物粒度较细，以细砂岩和粉砂岩为主。垂向层序为正粒序。沙三中亚段具沟道、沟道间、席状砂和泥石流等微相沉积的特征。     

Detrital zircon provenance evidence for an early Permian longitudinal river flowing into the Midland Basin of west Texas

ABSTRACT

Collision of Gondwana and Laurentia in the late Palaeozoic created new topography, drainages, and foreland basin systems that controlled sediment dispersal patterns on southern Laurentia. We utilize sedimentological and detrital zircon data from early Permian (Cisuralian/Leonardian) submarine-fan deposits in the Midland Basin of west Texas to reconstruct sediment dispersal pathways and palaeogeography. New sedimentological data and wire-line log correlation suggest a portion of the early Permian deposits have a southern entry point. A total of 3259 detrital zircon U-Pb and 357 εHf data from 12 samples show prominent groups of zircon grains derived from the Appalachian (500–270 Ma) and Grenville (1250–950 Ma) provinces in eastern Laurentia and the peri-Gondwana terranes (800–500 Ma) incorporated in the Alleghanian-Ouachita-Marathon orogen. Other common zircon groups of Mesoproterozoic-Archaean age are also present in the samples. The detrital zircon data suggest throughout the early Permian, Appalachia and Gondwana detritus was delivered by a longitudinal river system that flowed along the Appalachian-Ouachita-Marathon foreland into the Midland Basin. Tributary channels draining the uplifted Ouachita-Marathon hinterland brought Gondwana detritus into the longitudinal river with headwaters in the Appalachians or farther northeast. This drainage extended downstream westward and delivered sediments into the Permian Basin near the west terminus of the Laurentia-Gondwana suture. Estimated rates of deposition and proportions of zircons from more local (Grenville) versus more distal (Pan-African) sources indicate that river strength decreased throughout early Permian time. Primary sediment delivery pathway was augmented by minor input from the Ancestral Rocky Mountains and wind deflation of fluvial sediments north and east of the basin. Slope failure associated with early Permian deposition in the southeastern margin of the Midland Basin triggered gravity flows leading to submarine fan deposition.     

Triassic carbonate submarine fans along the Arabian platform margin, Sumeini Group, Oman

ABSTRACT The Sumeini Group formed along the passive continental margin slope that bounded the northeastern edge of the Arabian carbonate platform. With the initial development of this passive continental margin in Oman during Early to Middle Triassic time (possibly Permian), small carbonate submarine fans of the C Member of the Maqam Formation developed along a distally steepened slope. The fan deposits occur as several discrete lenticular sequences of genetically related beds of coarsegrained redeposited carbonate (calciclastic) sediment within a thick interval of basinal lime mudstone and shale. Repeated pulses of calciclastic sediment were derived from ooid shoals on an adjacent carbonate platform and contain coarser intraclasts eroded from the surrounding slope deposits. Sediment gravity flows, primarily turbidites with lesser debris flows and grain flows, transported the coarse sediments to the relatively deep submarine fans. Channel erosion was a major source of intraformational calcirudite. Two small submarine fan systems were each recurrently supplied with calciclastic sediment derived from point sources, submarine canyons. The northern fan system retrogrades and dies out upsection. The southern fan system was apparently longer-lived; calciclastic sediments in it are more prevalent and occur throughout the section. The proximal portions of this fan system are dominated by channelized beds of calcirudite which represent inner- to mid-fan channel complexes. The distal portions include mostly lenticular, unchannelized beds of calcarenite, apparently mid- to outer-fan lobes. Carbonate submarine fans appear to be rare in the geological record in comparison with more laterally continuous slope aprons of coarse redeposited sediment. The carbonate submarine fans of the C Member apparently formed by the funnelling of coarse calciclastic sediment into small submarine canyons which may have developed due to rift and/or transform tectonics. The alternation of discrete sequences of calciclastic sediment with thick intervals of ‘background’ sediment resulted from either sea-level fluctuations or pulses of tectonic activity.     

辽河盆地大凌河油层湖底扇沉积特征

辽河盆地位于辽宁省南部,渤海湾盆地东北角,是继中生代发育起来的第三纪断陷盆地。分东部凹陷,西部凹陷和大民屯凹陷等二级构造单元(图1)。     

陕甘宁地区晚古生代沉积体系

陕甘宁地区位于华北地台西部,处于东西构造域的交接部位,是我国重要的含煤、油气区之一。受不同构造背景、海平面升降、沉积物供给等影响,其晚古生代沉积体系类型多样。通过对露头、岩心、测井响应及编图等分析研究,区分出了碳酸盐台地、障壁岛－湖潮坪、潮道－湖潮坪、河控三角洲、扇三角洲、河流、冲积扇、湖泊等沉积类型,阐明了各自的沉积特征。晚古生代沉积体系展布、充填演化与南北两侧的兴蒙海槽和秦祁海槽的构造活动密切相关：晚石炭世西缘拗拉槽重新复活,形成以潮道－湖潮坪沉积为主的海湾充填,充填受基底和盆缘断裂控制;早二叠世东西部海水汇合,本区统一于华北陆表海中,形成碳酸盐台地、障壁岛、浅水三角洲交互的含煤沉积;中二叠世至晚二叠世早期陆表海萎缩,本区演变为近海内陆坳陷充填,形成冲积扇、河流、三角洲、湖泊沉积;晚二叠世晚期陆表海消亡,本区转化为内陆坳陷,形成以湖泊沉积为主的河湖充填。砂储层发育取决于沉积环境,空间展布受控于古构造机制。     

Deposition and derivation of clastic carbonates on a Mesozoic continental margin, Othris, Greece

The Othris Mountains of eastern Greece contain a calcareous continental margin/ocean basin sequence exposed in a stack of Cretaceous thrust sheets. Upper Triassic to Lower Cretaceous shelf, submarine fan and basinal successions overlie shallow marine units of Lower Triassic and Permian age. In off-shelf sequences the older sediments are separated from the younger by a horizon of alkaline ‘early-rifting’ basalts. Ophiolites overthrust the marginal sequence. Pre-rifting sediments are represented by a varied suite of limestones and clastics resting on metamorphic basement and include distinctive, green lithic arenites. In the thrust sheet immediately over the para-autochthonous shelf sequence, pre-rifting sediments are separated from the rift basalts by an intermittent horizon of calcareous sandstones and conglomerates reworked from uplifted basement and older sediments. Textural and petrographic immaturity suggests that these are probably deposits derived from fault scarps, produced in an early phase of rifting. Above the basalts in the same sheet is a suite of calciclastic sediment-gravity-flow deposits, apparently sedimented on a submarine fan. Progressive downslope modification of calcirudites suggests deposition from evolving, high concentration flows. Massive calcarenite facies (? grain flows) are unusually abundant; a possible reflection of a shallow palaeo-shelf break since provenance and palaeocurrent evidence proves the clastic carbonates to have been derived from a calcareous shelf. In addition to limestone lithoclasts the calcirudites, but not the massive calcarenites, contain fragments of pre-rifting lithologies including the distinctive arenites. Since the shelf sequence in Othris is totally nondetrital these clasts imply derivation of coarse sediment from an off-shelf position; probably the walls of a submarine canyon. This may have occurred either by direct erosion of wall rock, or by reworking of material from an older clastic sequence. In the latter case the inferred fault-scarp deposits are a likely source.