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1.
根据海侵层与陆相层相间的特点，Ｏｌｄｕｖａｉ亚时以来南黄海沉积层序可划分为１５个地层段，据相分析存在着７个海侵层和１个具海侵迹象的层位。主要海侵层都具备经典的海侵－海退相序列。陆架区古地现演变可分为４个时期：（１）１．７０－０．５０Ｍａ，古长江河流平原和三角洲发育时期。Ｏｌｄｕｖａｉ亚时期间，ＱＣ２孔发现感潮河段河床沉积，河口在１２４＾ｏ附近。０．９７－０．７３Ｍａ海侵期，在１２２．２＾ｏＥ以东形 相似文献
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南黄海盆地中部隆起上古生界沉积环境探讨 总被引：1，自引：0，他引：1
CSDP-2井是大陆架科学钻探计划（CSDP）在南黄海盆地中部隆起实施的第一口连续取芯井,完井深度2 843.18 m,平均取芯率高达97.7%。综合利用该井岩芯、测井、岩石薄片及古生物化石资料,准确识别出南黄海盆地中部隆起上古生界的岩石类型、沉积构造、岩性组合序列等特征,进而探讨研究区沉积环境及其垂向演化规律。研究结果显示:CSDP-2井所钻遇的二叠系、石炭系、泥盆系地层既包含碎屑岩也包含碳酸盐岩,发育了三角洲相、滨岸相、潮坪相、碳酸盐岩台地相、浅海陆棚相等多种沉积相类型;南黄海盆地晚古生代先后经历了两个完整的海侵-海退旋回,自下而上发育碎屑岩浅海-潮坪沉积体系、碳酸盐岩潮坪-潟湖-颗粒滩沉积体系和碎屑岩三角洲沉积体系,反映了研究区由海相向海陆过渡相逐渐演化的沉积充填过程。 相似文献
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羌塘盆地地处藏北高原,其南、北边界分别为班公错一怒江缝合带与拉竹龙一金沙江缝合带,盆地面积约18×104km2,可进一步分为羌北坳陷、中央隆起带和羌南坳陷3个二级构造单元.双湖托纳木地区地处羌北坳陷南部,与中央隆起带毗连,广泛发育上侏罗统雪山组沉积,垂向上由3个沉积旋回组合构成,总体显示为一个向上变粗的充填序列.雪山组发育扇三角洲相和冲积扇相,其中雪山组一段为前扇三角洲亚相沉积;二段为扇三角洲前缘亚相和扇三角洲平原亚相沉积,扇三角洲前缘亚相分为水下分流河道、河口坝和远砂坝沉积,扇三角洲平原亚相发育天然堤和分流河道沉积;三段为冲积扇相沉积,包括扇端和扇中沉积.雪山组沉积的物源来自西南部的中央隆起带. 相似文献
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应用800多口钻孔及文献资料,讨论了中国沿海滦河扇三角洲、长江三角洲和珠江三角洲及钱塘江河口湾4个地区的下切河谷体系,这些皆为丰沙河流形成的河口三角洲。这些河口三角洲地区的下切河谷为长形或扇形,长数十至数百千米,宽数十千米,深40～90 m。河口三角洲地区的下切河谷相序可分为4种类型,即FS-Ⅰ,FS-Ⅱ,FS-Ⅲ和FS-Ⅵ。可以将这4类相序自海向陆排成一个理想序列：FS-Ⅰ位于海岸线附近,FS-Ⅳ位于河口三角洲的顶部,显示海的影响逐渐减弱,陆相作用逐渐增强。下切河谷层序可分为海侵和海退序列。海侵序列的厚度占下切河谷层序的50％以上,体积占60％～70％。海侵序列是在海平面上升过程中,溯源堆积依次叠置而成的,其下部的河床相是在溯源堆积能到达、而涨潮流未能到达的下游河段产生的,往往不含海相微体化石和潮汐沉积构造。在海侵序列中未见区域上可对比的侵蚀面,表明冰后期海平面上升速率的变化、甚至小幅下降也未留下统一的侵蚀记录。下切河谷中的海退序列由河口湾充填及三角洲进积而成,其进程是各不相同的：长江古河口湾先被强潮河口湾相、后由三角洲相所充填,河口湾也经历了由强潮型向中潮型的转变;滦河扇三角洲和珠江三角洲,其古河口湾则被河流相和三角洲相所充填;钱塘江河口湾正被强潮河口湾相所充填。 相似文献
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南黄海海域晚古生代—新生代沉积演化特征 总被引：1，自引：0，他引：1
南黄海地区发育古生界-第四系沉积。加里东运动使华南褶皱带与扬子地台拼接，在下扬子地台的主体部分，形成一个广阔稳定的后加里东台地。早中泥盆世台地处于剥蚀夷平阶段。晚泥盆世开始接受内陆河流相沉积。中、晚石炭世，海侵加强，包括勿南沙隆起区在内的整个南黄海成为浅海环境，接受碳酸盐岩沉积。早、晚二叠世之间的东吴运动，引起裂陷和陆棚的沉积分异，湖泊-滨岸沉积发育，并形成多个煤层。早三叠世早期，下扬子区大幅沉降，全区遭受海侵，台地灰岩、浅海灰泥岩沉积区占据了现今的黄南盆地、中部隆起及黄北盆地的大部分区域。至中三叠世早期，海水大规模退出苏浙皖区，南黄海演变为潮坪，沉积了较厚的碳酸盐岩，局部地区出现渴湖环境；晚期，海水全部退出苏浙皖区，开始沉积以河、湖相为主的黄马青组红色碎屑岩，至此结束了海相沉积历史。印支运动早期，后加里东地台的南侧产生裂谷，北侧为边缘坳陷。印支运动晚期，南侧裂谷伴随着郯庐断裂的左旋走滑而进一步扩大和裂陷，形成黄南盆地。中三叠世末，随扬子地台与华北地台碰撞加剧，苏鲁造山带形成并不断上升，在其南缘形成前陆盆地。中生代黄北盆地和黄南盆地内河流相、湖相沉积和中酸性火山岩发育，沉积总厚度达3000～6000m。古新世-渐新世末，黄海进入断陷发育阶段，古新世-始新世，湖相沉积占优势，渐新世沼泽沉积发育。中新世-第四纪南黄海转入区域性坳陷沉降，主要发育河流相沉积。 相似文献
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安塞油田王窑地区长6油层沉积微相研究 总被引：16，自引：4，他引：16
王窑地区长6油层为湖泊河控三角洲前缘沉积。主要沉积微相为三角洲前缘水下分流河道、分流河口砂坝、前缘砂席和分流间等。水下分流河道充填沉积为向上变细的砂岩层序，分流河口砂坝可期分为向上变粗的前积式和非前积式两种沉积层序类型。水下分流河道和河口砂坝砂体相互连接，形成厚度较稳定的三角洲前缘复合体。该区三角洲沉积是安塞三角洲发育较晚的一支，也是指状砂体仲入湖区最远、发育程度最高的分支。长61^1沉积期。为三角洲的初始进积阶段。三角洲沉积由两支分流组成。长61^2沉积期三角洲前缘体系完整，砂体发育，分流带相互叠置交错。根据岩心描述结果，结合砂体形态和连井剖面对比分析，对长6油层三角洲沉积微相进行了综合表征。并提出了开发调整意见，为王窑地区特低渗透油田的高效开发奠定了地质基础。 相似文献
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早石炭世海侵范围较小，莫莫克以东为古岛，以西为向北西倾斜的水下隆起，为局限台地--开阔台地相清水碳酸盐岩和混积陆棚相沉积：晚石炭世早期海侵范围扩大．铁克力克古岛沦为水下隆起，莫莫克以西为较厚的混积陆棚相和滨岸相砂岩沉积．以东为局限台地-开阔台地相清水碳酸盐岩沉积；晚石炭世中期为稳定的海侵期，形成潮坪-局限台地．开阔海台地相清水碳酸盐岩沉积：晚石炭世晚期--一早二叠世早期为规模最大的海侵期，也是塔西南碳酸盐岩台地发育的鼎盛时期，其重要标志是形成了台地边缘礁滩相带，高能浅滩相最为发育．莫莫克以西地区下二叠统棋盘组为海陆交互相沉积、上二叠统达里约尔组为湖泊一河流相沉积．莫莫克以东地区下二叠统普司格组为河流-湖泊-扇三角洲相沉积、上二叠统杜瓦组为冲积扇-扇三角洲相沉积． 相似文献
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饶阳凹陷沙河街组主要为砾岩、含砾砂岩、砂岩、粉砂岩和泥岩构成的一套碎屑岩组合,根据沉积特征将其确定为辫状河三角洲沉积.该沉积三层结构清楚,由下而上出现前辫状河三角洲亚相、辫状河三角洲前缘亚相及辫状河三角洲平原亚相,呈明显的进积层序,主要发育辫状河道、洪泛平原、水下分流河道、水下分流河道间、河口坝和席状砂等沉积微相.据其岩性、沉积构造、粒度及沉积序列等特征,建立了沉积模式.从岩性特征看,沙河街组辫状河三角洲沉积物具有分布较广、储集物性较好的特点,辫状河三角洲前缘水下分流河道砂体和河口坝砂体储集物性最好,是下一步勘探的有利目标. 相似文献
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珠江三角洲中山横栏地区晚第四纪以来的沉积特征 总被引：1，自引：0，他引：1
中山横栏地区在珠江三角洲第四纪地层研究中具有代表性。本文通过对该地区第四纪Ⅳ01钻孔岩性、粒度及地球化学特征的综合研究,探讨珠江三角洲晚第四纪以来的沉积特征。结果表明,珠江三角洲晚第四纪沉积物自下而上包含三次沉积旋回:一次晚更新世海侵旋回和两次全新世的海侵旋回,其形成的下粗上细正向序列在进积型三角洲中具有一定的特殊性;在沉积学分析的基础上,结合粒度和微量元素B、Ba、Sr的指相特征,探讨珠江三角洲晚第四纪以来的海侵-海退旋回,揭示在中全新世中晚期(约5~2.5 ka BP)发生了海退过程,进一步印证中山横栏地区晚第四纪以来存在三次海侵事件的认识。 相似文献
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基于区域地质背景资料,综合运用岩芯观察、岩相和测井相分析等手段,对临南油田街2断块沙三上亚段Ⅴ砂岩组沉积微相的沉积相标志、类型以及展布特征进行了系统研究。结果表明：临南油田街2断块沙三上亚段Ⅴ砂岩组为一套湖泊三角洲沉积体系,亚相类型为三角洲前缘亚相;沙三上亚段Ⅴ砂岩组主要沉积微相可细分为水下分流河道、水下分流河道间湾、河口坝、远砂坝和前缘席状砂等5种微相,并建立了沉积微相识别模式;沉积特征和沉积微相的平面展布呈现在近东西向剖面上砂体连续性较好,可见河口坝与前缘席状砂的交替出现,而在近西南—北东向剖面上,砂体横向上一般由水下分流河道过渡到河口坝或前缘席状砂。总之,临南油田街2断块沙三上亚段Ⅴ砂岩组是研究区三角洲形成的高峰期,水下分流河道、河口坝、前缘席状砂为主要的储集砂体。 相似文献
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陕甘宁盆地华池地区延长组缓坡带三角洲前缘的微相构成 总被引：41，自引：7，他引：41
以晚三叠世华池地区延长组为例,对缓坡背景下的三角洲前缘水下分流河道和河口坝两种主要储油微相进行研究,建立了分类方案和识别标志。将水下分流河道划分为截削式和完整式两大类 10种类型;河口坝细分为孤立式、叠加式和复合式三大类 5种类型。文中根据入湖后的水下分流河道能量强弱变化和湖水深浅的不同组合关系,对水下分流河道和河口坝的沉积条件进行分析,归纳总结了本区缓坡条件下的三角洲前缘的沉积模式。同时讨论了本区独具特色的复合式坝 (“坝上河”)沉积微相的成因类型 :分流河道侵蚀河口坝型复合式河口坝和分流河道叠加河口坝型复合式坝,而后者是该区主要的优质储层和高产含油储层类型 相似文献
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The Attawapiskat River is one of the major low-gradient rivers which cross the flat wetlands of the Hudson Bay Lowland. It has a nival regime leading to strong, short-duration spring floods during which considerable amount of sediment is carried. For the remainder of the year only organic matter is transported in solution and suspension. The land is isostatically rebounding after the Pleistocene glaciations. The river downcuts through the softer Holocene estuarine basal clays and the Pleistocene tills, to the Paleozoic carbonate bedrock. The river develops an anastomosing pattern in the lower reaches and it acquires an irregular meandering character inland. It does not construct a significantly thick delta as the river-borne sediments are dispersed along the coasts by tides, longshore currents and ice rafting. The river is subjected to frequent ice jams in its lower reaches as warmer southern waters flow toward the still frozen mouth and sea. During the jams, secondary channels become active, floodings develop and sedimentation occurs on the levees. Ice scours and ice-rafted materials affect the river banks greatly.The principal sedimentary environments within the river consist of: (1) erosional shoals covered by boulder and pebble lags over till: (2) sorted coarse to medium-sized sands in junction bars downstream from islands; these sands frequently develop gas bubbles, and they contain characteristic fining-upward sequences from boulder pavements at the base, grading up into rippled sand with abundant organic matter, grading up into laminated silt and sand and organic matter; (3) secondary channels, which develop thin silty and clay drapes on eroded hard substratum and are filled eventually by thick peats; and (4) river banks which show well-developed regressive sequences from Pleistocene tills at the base, overlain by estuarine sparsely fossiliferous clays, capped by thin conglomeratic units with abundant reworked Macoma balthica shells, grading upward into upper tidal flat sand, irregularly laminated sand and silt of marshes, and regular interbedding of sand, silt and organic layers of the levees at the top. 相似文献
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泥河湾盆地东部郝家台地区的台儿沟东剖面主要出露地层为更新统和上新统,剖面顶部为厚9.4 m的马兰黄土和古土壤,剖面中部由更新统郝家台组和泥河湾组构成,剖面下部为上新统蔚县组。郝家台组和泥河湾组为三角洲平原、三角洲前缘和少量前三角洲亚相沉积组合,其中三角洲平原亚相可分为分支河道、分支间湾、天然堤、沼泽和淡水湖泊5个微相,由发育大型板状斜层理和底冲刷面构造的粗砂夹砾石透镜体,含钙质结核的透镜状黄褐色中 细砂以及富含炭屑的深色粘土等共同构成;三角洲前缘亚相则由水下分支河道、支流间湾、河口砂坝和末端砂坝构成,以发育底冲刷面构造并夹有细砾石透镜体的细中粒砂、小型板状斜层理细砂以及分选好且质纯的细砂等组合为特征;前三角洲亚相相对不发育,主要由浅灰色粘土以及灰绿色、灰黑色粘土夹钙质结核构成。蔚县组主要由滨湖亚相和浅湖亚相构成,其中前者为多种颜色的并发育泥裂和滑塌构造的粘土、粉砂组合,局部夹有透镜状砂砾层,底冲刷面发育;后者主要由粉砂、粘土组合构成,局部可见由砂泥交互构成的透镜状层理。古水流分析结果表明,上新统蔚县组沉积物源区位于泥河湾盆地NE侧,更新统泥河湾组和郝家台组碎屑沉积物主要来自于NE和NW方向,而泥河湾组底部约15 m厚沉积物除了来自NE方向外,还有部分沉积物来自SSW方向物源区。表明自上新世以来,泥河湾盆地周边具有北高南低古地理格局,从而为盆地提供丰富的碎屑沉积物。 相似文献
15.
河海交互作用沉积与平原地貌发育* 总被引：3，自引：15，他引：3
河流是搬运陆源泥沙的主要动力,对相邻的海岸海洋沉积动力有巨大影响。中国河流汇入海洋中的泥沙曾占全球入海泥沙的10 ％ ,现代中国边缘海大陆架在晚更新世时曾是海岸平原,河-海交互作用是形成海岸平原与浅海输积泥沙的主要因素。本文选择5个不同类型的河流展示其不同的泥沙运动与河口沉积的特性以及对相邻陆架之影响,包括: 1)强潮型动力的鸭绿江河口湾,形成从陆向海与从海向陆的双向水流交汇沉积,海岸形成潮流脊体系。 2)季风波浪为主导动力的滦河口,以泥沙的横向运动为主,形成沙坝环绕的双重海岸,沉积粒径自海向陆减小; 沿岸浪流携运泥沙向河口两侧分布,使沙坝具有沙咀状的复合特点。 3)弱潮型、多沙的黄河口,径流于两侧堆积指状沙咀,沙咀下风侧形成粉砂粘土淤泥湾,沿岸流携运泥沙向渤海湾延伸为淤泥舌。 4)径流与沿岸流组合作用的沉积模式,以长江口为代表,泥沙沿岸向南输运为主导,向海岸与向内陆架构成颗粒变细的带状沉积,外陆架出露残留砂。 5)充填河口湾的三角洲,以珠江为代表,河流分汊与会潮点泥沙堆积,悬移质扩散至湾外,被沿岸流携带沿海岸向SW运移,外陆架为残留砂沉积。20世纪80年代以来,上述河流均受到人为活动的改造影响,河流自然过程与河海交互作用效应均发生改变。本文主要以滦河三角洲为例阐述河-海交互作用与平原的地貌特征。 相似文献
16.
根据岩性组合变化、测井曲线叠加样式及地震反射特征,将东营三角洲沙三中亚段划分为八个期次,准层序组PS8~PS1,各期次间沉积小型湖泛泥岩楔。结合岩心及测录井沉积相分析,认为研究区发育三角洲-重力流-湖泊沉积体系。东南部主要发育三角洲分流河道、河口坝、席状砂,西北部发育与三角洲前缘滑塌相伴生的坡移堆积体、滑塌浊积岩和远源浊积岩。准层序组PS8~PS1,活动三角洲经历了由南至北的迁移演化过程。当波浪与河流能量能够抗衡并往复运动时,形成厚度较大的三角洲楔状体叠加区,沉积席状砂和河口坝砂体。受湖平面变化、构造沉降及沉积物供给速率的影响,湖退体系域早期PS7~PS4重力流砂体含油丰富,而浅水区准层序组界线附近的席状砂和河口坝由于临近具有侧向封堵及局部盖层作用的泥岩楔及沼泽沉积,其含油性也较好。 相似文献
17.
大凌河河口地区LZK06孔40m以浅岩心的沉积学、古生物学和年代学等综合研究以及该地区LZK02- 04钻孔资料,揭示了研究区中更新世晚期以来经历了两次海侵- 海退旋回,依次形成了中更新世晚期湖相/河流相 SymbolnB@ 晚更新世海相- 湖相/河流相 SymbolnB@ 全新世海相- 河流相地层。全新世早中期由于物源供给很少,研究区处于长达约10ka的饥饿滞留相沉积环境,平均沉积速率仅约0. 02~0. 05cm/a。全新世晚期约1500a cal BP以来,由于人类活动导致水土流失,河流输砂量增加,研究区开始了快速加积过程,平均沉积速率约0. 9~1. 2cm/a,下辽河平原被快速充填,开始成陆。与全球海面变化时空分布特征的对比,推断辽东湾的第II海相层发育于MIS 5- MIS 3早期,第I海相层发育于MIS 1阶段高海面时期。晚更新世以来频繁的海面升降是辽东湾泥质海岸带地层和环境演化的主要控制因素。 相似文献
18.
Joep E.A. Storms Robert M. Hoogendoorn Rien A.C. Dam A.J.F. Hoitink S.B. Kroonenberg 《Sedimentary Geology》2005,180(3-4):149-166
The late-Holocene Mahakam delta, located along the tropical eastern shore of Kalimantan, Indonesia, is considered to be a textbook example of a mixed tide–fluvial dominated delta system. The delta prograded about 60 km during the past 5000 years, which led to the development of a distinct network of distributary and tidal channels. Wave action is low due the limited fetch in the narrow strait of Makassar. Mahakam River discharge is about a quarter of the Mississippi River discharge and is characterized by absence of flood surges. Therefore, natural levees, crevasse splays and avulsions are absent in the delta plain. For the past four decennia, both modern and ancient Mahakam delta deposits have been studied in detail in order to better understand subsurface Miocene and Tertiary Mahakam deposits, which host large volumes of hydrocarbons.
This study focuses on the dynamics and stratal patterns of delta plain, delta-front platform deposits and suspended sediments. Due to the predominance of semi-diurnal tides and the associated flow reversals, depositional patterns are highly variable which has resulted in the formation of characteristic sand–mud couplets. The distribution of the sand–mud couplets found in this study differs from previously proposed conceptual models. They are limited to the fluvial domain and form in the distributary channels (lateral channel bar) or at the fluvial dominated delta-front platform, which flanks the mouth bar deposits in offshore direction. The sand–mud couplets which formed as delta-front platform and lateral channel bar deposits are similar and can only be identified based on their 14C age. The sand content decreases significantly towards the tidal dominated areas due to limitation in transport capacity. Turbidity measurements taken in front of the river mouth also show rapid settlement of river plume sediments.
Some 22 new AMS 14C dates show that late Holocene sea level history resembles the eustatic sea level curve giving a first approximation of the Late Holocene sea level history for East Kalimantan. The dates suggest that the progradational delta system evolved under conditions of slowly rising sea level, which compares well to the eustatic sea level curve. In addition, calculated averaged deposition rates of the sand–mud couplets indicate that deposition is driven by the spring–neap tide cycles instead of the daily tidal cycle. 相似文献
19.
Pleistocene sediments at Leet Hill, southern Norfolk are examined in terms of their sedimentary structures, palaeocurrent indicators, clast and heavy mineral lithology and litho- and morphostratigraphic position. Colour of the quartzite and vein-quartz clasts is used to differentiate the Bytham and the Kesgrave sands and gravels, with the Bytham sands and gravels having a significantly higher proportion of coloured material. The Kirby Cane sands and gravels are the lower sedimentary unit and were deposited by the Bytham river, which drained a catchment extending into central England. At Leet Hill, erosion of the Kesgrave Sands and Gravels by the Bytham river has given the Kirby Cane sands and gravels a distinctive lithological assemblage. Trace clast lithologies suggest that the Kesgrave Sands and Gravels in the region of Leet Hill were deposited in a coastal location with an input from northern sources as well as southern and Welsh sources diagnostic of the Thames catchment. The glaciofluvial Leet Hill Sands and Gravels were deposited by outwash from the Anglian Scandinavian ice sheet. Initially the flow direction of the outwash was determined by the Bytham river valley, but this changed to a southerly direction once the valley had been infilled. This paper provides the first indication of the location of the boundary (Early Pleistocene coastline) between the fluvial Kesgrave Sands and Gravels and the marine equivalent reworked by coastal processes, and demonstrates the way the pre-glacial relief initially controlled patterns of glaciofluvial sedimentation during the early part of the Anglian glaciation. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
20.
Muddy deltas in freshwater lakes, and tectonism in the Upper Carboniferous Coalfield of NE England 总被引：1，自引：0，他引：1
R. S. HASZELDINE 《Sedimentology》1984,31(6):811-822
ABSTRACT
The Westphalian B sediments of NE England were deposited on part of a coastal plain with subdued relief. Most of the fine-grained sediments were deposited by small fluvially dominated muddy deltas which fed into shallow freshwater lakes in tectonic depressions a few metres deep and a few tens of kilometres across.
Coalfield lakes contained an abundant low-diversity bivalve fauna and existed for thousands of years before delta infill. Pro-delta clay rhythmites, formed by flood turbidites, coarsened up into wide silty mouth bars, which merged up into channel mouth sands, inversely-graded subaqueous levee deposits and sandy channel fills. Delta complexes were either abandoned below water level leaving a lake, or were colonized by plants, which resulted in trapping of suspended sediment and build-up of a seatearth to near water level when peats could accumulate. These swamps were analogous to the present raised bogs of Indonesia and had a lateral zonation of vegetation to a central low-diversity flora. Upwards reversal of this zonation and the succession of coals by lake sediments show that peat floras were killed by drowning due to rapid tectonic subsidence. Subsurface data show that seam splits and sand-body locations were tectonically controlled, and that the lake deltas in this area were distant from any major sand distributary. 相似文献
The Westphalian B sediments of NE England were deposited on part of a coastal plain with subdued relief. Most of the fine-grained sediments were deposited by small fluvially dominated muddy deltas which fed into shallow freshwater lakes in tectonic depressions a few metres deep and a few tens of kilometres across.
Coalfield lakes contained an abundant low-diversity bivalve fauna and existed for thousands of years before delta infill. Pro-delta clay rhythmites, formed by flood turbidites, coarsened up into wide silty mouth bars, which merged up into channel mouth sands, inversely-graded subaqueous levee deposits and sandy channel fills. Delta complexes were either abandoned below water level leaving a lake, or were colonized by plants, which resulted in trapping of suspended sediment and build-up of a seatearth to near water level when peats could accumulate. These swamps were analogous to the present raised bogs of Indonesia and had a lateral zonation of vegetation to a central low-diversity flora. Upwards reversal of this zonation and the succession of coals by lake sediments show that peat floras were killed by drowning due to rapid tectonic subsidence. Subsurface data show that seam splits and sand-body locations were tectonically controlled, and that the lake deltas in this area were distant from any major sand distributary. 相似文献