鄂尔多斯盆地中奥陶统马家沟组沉积环境与岩相发育特征

鄂尔多斯盆地位于华北地台西部 ,中奥陶统马家沟组含硬石膏的白云岩是盆地中主要的储层与产层之一。奥陶纪由于西侧贺兰裂谷再次开启 ,裂谷肩部发生抬升 ,以及南侧逆冲断层的左行走滑作用 ,在盆地西部和南部形成一“L”形隆起 ,又称中央隆起。在隆起东侧由均衡补偿作用伴生一西缓东陡的边侧坳陷 (盆地 ) ,称 (内 )陆棚盆地亚环境。通过沉积相研究 ,建立了两个马家沟组的沉积模式。其一为东西向穿越 (内 )陆棚盆地中心的陆棚沉积模式 ,该模式中的 (内 )陆棚盆地与中央隆起之间为水下凸起-洼地亚环境 ,其东为开阔内陆棚亚环境。马一时、马三时、马五时(内 )陆棚盆地发育为含白云岩的硬石膏岩 ,石盐岩盆地 ,盆缘主要发育白云岩-硬石膏岩坪 ,马五时西缘硬石膏岩-白云岩坪发育 ,是天然气藏主要分布区。以上表明沉积时气候干热 ,海平面下降 ,具深坳陷海水浓缩成盐特征。马二时、马四时气候湿热 ,海平面上升 ,(内 )陆棚盆地发育成石灰岩白云岩盆地 ,周围盆缘发育为 (含 )白云岩-石灰岩坪。水下凸起-洼地亚环境于马三时和马五时发育白云岩 ;马四时发育石灰岩 ,南延则过渡为白云岩、石灰岩的浅滩。东侧的开阔内陆棚亚环境 ,主要发育微晶-亮晶颗粒石灰岩、白云岩夹硬石膏岩、风暴岩。马六时 ,中央隆起以东根     

鄂尔多斯盆地南部下奥陶统马家沟组沉积特征

依据鄂尔多斯盆地南部早奥陶世古构造、古地理、古水动力以及古气候背景,结合单井、野外露头沉积相分析等认为,秦岭海槽和中央古隆起的存在和演化控制盆地南部马家沟组沉积特征及演化。(1)平面上根据中央古隆起的障壁作用将其分为两大沉积区,西南区和东北区。西南区发育盆地—斜坡—台地边缘相,东北区为障壁潟湖沉积环境;(2)东北区马家沟组由"三云三灰"六段组成,马一、马三、马五段为白云岩、石膏和石盐组成的蒸发岩系,马二、马四、马六段为石灰岩夹白云岩的碳酸盐岩序列,在纵向上构成蒸发岩与碳酸盐岩间互的旋回性沉积。在此基础上进一步建立了马家沟组障壁潟湖沉积模式,该模式具有两个主要特征:(1)中央古隆起作为障壁控制秦岭海与潟湖之间的海水沟通;(2)依据海平面升降旋回将该模式动态地分为三个阶段,即与海侵期相对应的以石灰岩沉积为主的障壁潟湖沉积阶段(阶段Ⅰ)、与海退期相对应的以石灰岩夹蒸发岩沉积为主的障壁咸化潟湖沉积阶段(阶段Ⅱ)和与低海平面期对应的以膏盐岩沉积为主的障壁膏盐湖沉积阶段(阶段Ⅲ)。     

延安地区奥陶系马家沟组上组合膏盐岩成盐沉积演化模式研究

延安地区经过十余年油气勘探,在奥陶系马家沟组获得了一系列的突破,其中马家沟组上组合是天然气勘探的重要层位,该区是奥陶系碳酸盐岩- 膏盐岩共生体系的主要沉积区,其中马家沟组上组合马五43- 马五32膏盐沉积是海退蒸发环境的典型代表。本文基于延安气田奥陶系天然气勘探的最新进展,利用现场岩心观察、实验分析、钻井及测井资料,根据沉积构造、膏盐岩发育规模、岩性组合方式等,对研究区奥陶系马家沟组上组合膏盐岩的地质特征进行了详细的阐述,系统地总结了研究区马家沟组上组合膏盐岩的沉积背景及沉积相、建立了沉积演化模式,为延安气田膏盐岩研究提供基础资料。研究表明,在西高东低的沉积格局背景下,地层充填呈西薄东厚,南薄北厚的特点;自西南向东北依次为膏质白云岩- 膏岩- 盐岩沉积区;垂向发育三种岩石类型组合：Ⅰ型膏质白云岩- 硬石膏结核白云岩- 膏质白云岩- 泥云岩组合,Ⅱ型膏岩- 硬石膏结核白云岩- 膏质白云岩- 泥云岩组合,Ⅲ型盐岩- 膏岩- 硬石膏结核白云岩- 膏质白云岩组合;沉积环境为相对安静且低能的潟湖沉积模式。沉积环境演化为极强蒸发盐化→蒸发膏化→相对开放。研究成果为鄂尔多斯盆地其他地区奥陶系膏盐岩地质研究提供借鉴,对延安气田油气勘探具有重要指导意义。     

鄂尔多斯盆地马家沟组碳酸盐岩-膏盐岩共生体系沉积微相与沉积模式

碳酸盐岩-膏盐岩共生体系是化学沉积分异作用形成的岩石共生组合,对其进行微相分析和沉积模式构建,有利于揭示蒸发环境下的沉积学信息,对油气勘探具有指导意义。依据鄂尔多斯盆地奥陶系马家沟组大量钻井、岩心资料,开展岩石宏观、微观观察,识别沉积微相,分析沉积序列,构建沉积模式。结果表明:马家沟组碳酸盐岩-膏盐岩共生体系可划分出10类微相(MFT1-MFT10):盐岩、膏岩、含膏云岩、纹层状微粉晶云岩、颗粒云岩、粉—细晶白云岩、微生物云岩、生物扰动(灰)云岩、纹层状微晶灰岩、微晶颗粒灰岩;共生体系发育4类微相组合:(1)潮间上带—潮上带白云岩-含膏云岩-泥云岩组合;(2)潮间下带膏岩-藻云岩-白云岩组合;(3)潮下带纹层状灰岩-搅动灰岩-扰动灰岩组合;(4)潟湖内层状膏岩-团块状膏岩-盐岩组合。马家沟组为浅盆蒸发成盐,低海平面蒸发成盐,高海平面发育碳酸盐岩,海平面反复波动形成巨厚碳酸盐岩—膏盐岩共生组合。     

鄂尔多斯盆地中东部奥陶系马五_5亚段白云岩地球化学特征及成因模式

依据岩心、薄片以及实验分析资料,表明鄂尔多斯盆地中东部奥陶系马五_5亚段白云岩碳同位素分布区间与泥晶灰岩的分布区间类似,均介于-1.40‰~0.14‰,分布在同期海水值区间内;氧同位素组成介于-7.51‰~-5.98‰,较泥晶灰岩的偏正,但整体均较同期海水值偏负;稀土元素的配分模式与泥晶灰岩的相似,具有轻稀土元素富集、重稀土元素亏损的特征;锶同位素也和泥晶灰岩的分布范围大致相当,且具有少数正常、多数偏正的特征。综合古气候、古沉积格局和海平面升降变化的特征,认为:(1)马五_5亚段白云岩主要由渗透回流白云石化作用形成,部分由蒸发泵白云石化作用形成;(2)白云岩空间分布受海平面升降变化与沉积古地貌背景的共同控制,古地貌较高的中央古隆起—靖西台坪和靖东隆起带这两个区域上白云岩在相对海退期更为发育;(3)白云石的岩石结构组分之间的差异性与其形成的沉积背景有关,粉晶白云岩在中央古隆起—靖西台坪和靖东隆起带上均广泛发育,颗粒白云岩和含硬石膏结核粉晶白云岩仅零星分布在中央古隆起—靖西台坪带上,而白云石化不彻底的灰质粉晶白云岩和白云质泥晶灰岩主要分布在洼地中心和边缘地带。     

重新认识鄂尔多斯南部早奥陶世马家沟期碳酸盐台地沉积模式

地层、沉积岩组合及古地貌特征显示,鄂尔多斯盆地南部地区早奥陶世马家沟期为3个沉积单元区,即:北东部区为白云岩-蒸发盐组合;南部区为白云岩-少量蒸发盐组合;西部区以石灰岩为主。相应地北东部区以发育台内盆地-盆缘坪为主;南部区发育洼地-台坪-台地边缘-海槽;西部区则发育台地边缘-海槽。野外剖面与钻井岩心观测以及区域资料研究表明,鄂尔多斯盆地南部边缘大致在洛南瓦窑沟—西安—宝鸡一带。马家沟期研究区沉积模式总体上为:横向上"西槽、南洼、东坪、北盆",纵向上"咸-淡交替";灰岩-白云岩-蒸发岩横向上呈带状展布,纵向上则为不等厚交替沉积。     

鄂尔多斯盆地中东部奥陶系马家沟组沉积相演化模式研究

通过野外露头、岩心和薄片观察,结合测井资料,综合古气候、古沉积格局分析,系统地总结了鄂尔多斯盆地中东部奥陶系马家沟组沉积微相类型,并建立了沉积相演化模式。研究表明:(1)鄂尔多斯盆地中东部马家沟期具有"隆洼相间型"和"平底锅型"两种古沉积格局并存的特征;(2)主要发育9种微相类型,根据不同海平面高度的沉积微相平面组合类型,可将一个完整的海侵—海退旋回细分为海侵初期、中期和末期,海退初期、中期和末期等6个演化阶段;(3)古气候、古沉积格局和海平面升降变化共同控制了马家沟组生储盖分布,指出位于海侵期的东部隆起带及邻近区域发育的颗粒滩和白云岩坪,具有良好的成藏条件,有望成为一个碳酸盐岩勘探新领域。     

东秦岭柞水-镇安地区泥盆纪沉积环境和沉积盆地演化

东秦岭陕南柞水-镇安地区泥盆纪沉积盆地中主要发育有冲积扇、小型辩状河、河口湾、潮坪、潮下洼地、台地边缘生物滩、生物礁、开阔台地、斜坡和盆地沉积环境。台地沉积主要由陆源碎屑和碳酸盐混合类型岩石组成,斜坡-盆地为巨厚的陆源碎屑浊积岩充填。根据沉积作用特征和大地构造差异,在构造活动期和构造稳定期的沉积模式就反映了沉积盆地演化特征。 根据沉积作用,沉积环境的发展变化,结合区域构造特征、地层层序、岩浆活动和变质作用、地球物理和化学资料,论证了当时沉积盆地为南北向展布（与秦岭造山带总体方向垂直）,具向东走滑的大陆边缘裂谷-断陷盆地。盆地的发展演化阶段为:（1）岩石圈裂前拱起-陆内裂谷早期阶段（Z₂-S）;（2）大陆边缘裂谷-断陷盆地的中期阶段（D₁-D₃）;（3）晚期回返-陆内俯冲阶段（C-T₂）。盆地的关闭是由于强烈陆内俯冲,同时盆地被挤压进东西向展布的秦岭造山带。     

南大西洋两岸被动陆缘盆地结构差异与大油气田分布

以板块构造演化为基础,利用地震、地质等资料,再现南大西洋两岸共轭型被动陆缘盆地原型盆地形成演化过程。首次依据盆地结构差异及沉积充填特征,将研究区被动陆缘盆地进一步划分为“三段”“四类”;结合对已发现大油气田的解剖,搞清了每类盆地大油气田成藏规律,并分别建立了其大油气田成藏模式。认为两岸“三段”“四类”盆地都经过了早期陆内裂谷、过渡期陆间裂谷及漂移期被动陆缘三个原型阶段。南段为下伏裂谷层系比较发育的“断陷型”盆地,上覆坳陷沉积厚度较薄,仅作为区域盖层,形成“裂谷层系构造地层型”大油气田。中段为裂谷、坳陷层系都比较发育且过渡阶段有盐的“含盐断坳型”盆地,以过渡期陆间裂谷盐岩充填为特征,其上、下的漂移期海相及裂谷期湖相页岩均可形成有效烃源岩,海相页岩及盐岩分别作为优质盖层,形成了“盐下碳酸盐岩盐上重力流扇体型”大油气田。北段为裂谷层系分布范围小、坳陷沉积范围广且厚度大的“坳陷型”盆地,受 “窄”陆棚、“陡”陆坡控制,坳陷层系重力流扇体自始至终比较发育,源于坳陷层系下部海相页岩中的油气直接充注于本身内部裙边状分布的重力流复合扇体之中,形成“漂移期重力流扇体群型”大油气田。另外,研究区还发育尼日尔、福斯杜亚马逊、佩罗塔斯三个具有独特构造沉积特征的 “三角洲型”被动陆缘盆地,其特殊性体现在三角洲层系由于沉积速率极高,从陆向海形成生长断裂带-泥岩底辟带-逆冲断裂褶皱带-平缓斜坡带四大环状构造带。除了前三角洲层系可以作为有效烃源岩之外,本身也可以形成自生自储自盖型组合,形成独特的“四大环状构造带型”大油气田,即在由陆向海生长断裂带-泥岩底辟带-逆冲断裂褶皱带-平缓斜坡带四大环状构造带上都可以形成大油气田。     

扬子西缘鹤庆—洱源地区晚二叠世—晚三叠世盆-山演化的沉积记录

鹤庆—洱源地区位于扬子板块西缘,西邻“三江”结合带,晚二叠世—晚三叠世经历了完整的盆-山转换过程。通过分析该区地层岩性组合及沉积环境,结合构造事件,厘清了区内盆-山转换的时间格架及各阶段盆地沉积响应。研究结果表明: 区内盆地演化可分为陆内裂谷盆地、坳陷盆地和前陆盆地3个阶段; 裂谷盆地阶段沉积形成了巨厚的玄武岩沉积; 坳陷盆地阶段依次沉积了青天堡组碎屑岩、北衙组灰岩和白云岩; 前陆盆地阶段形成了中窝组和松桂组不整合界面及粗碎屑砾岩。研究成果对研究扬子西缘和“三江”特提斯构造带盆-山演化具有重要的科学意义。     

塔中地良奥陶系地层格架与沉积演化

塔里木中部地区奥陶系大致以Ⅰ号断裂为界分东北和西南两个地层分区,自下而上分白云岩段、灰岩段、泥质灰岩段、泥岩夹灰岩段、泥岩夹砂岩段、砂砾岩段、泥岩夹砂岩段、泥岩灰岩互层段和砂岩段等9个岩性段。早奥陶世,塔中地区以碳酸盐岩台地相为主,自西向东为局限台地相、开阔台地相、台地边缘相和深水斜坡相。中——晚奥陶世,塔中地区西部以混积陆架相为主,东部以深水斜坡相为主。中—晚奥陶世,塔中东部及塔东地区在构造上具弧后前陆盆地性质。中—上奥陶统地层完整地记录了该盆地从形成发展到消亡的过程,即早期为深水斜坡相复理石活动沉积,晚期演化为浅海陆架相稳定沉积。     

Late Quaternary shedding of shallow-marine carbonate along a tropical mixed siliciclastic–carbonate shelf: Great Barrier Reef, Australia

Abstract The north-east Australian margin is the largest modern example of a tropical mixed siliciclastic/carbonate depositional system, with an outer shelf hosting the Great Barrier Reef (GBR) and an inner shelf dominated by fluvially sourced siliciclastic sediment wedges. The long-term interplay between these sediment components and sea level is recorded in the Queensland Trough, a 1–2 km deep N–S elongate basin situated between the GBR platform and the Queensland Plateau. In this paper, 154 samples from 45 surface grabs and six well-dated piston cores were analysed for total carbonate content, carbonate mineralogy and Sr concentration to establish spatial and temporal patterns of carbonate accumulation in the Queensland Trough over the last 300 kyr. Surface carbonate contents are lowest on the inner-shelf (<5%) and in the trough axis (<60%) because of siliciclastic dilution. Carbonate on the shelf is mostly Sr-rich aragonite and high-Mg calcite (HMC), whereas that in the basin is mostly low-Mg calcite. Once normalized to remove the effects of siliciclastic dilution, surface Sr-rich aragonite and HMC abundances decrease linearly to background levels ≈ 100 km seaward of the shelf edge. Core samples show that, over time, normalized aragonite and Sr abundances are greatest during periods of shelf flooding and lowest when sea level drops below the shelf edge. This is consistent with changes in the production of coral and calcareous algae, and the shedding of their debris from the shelf. Interestingly, normalized HMC concentrations on the slope peak during periods of major transgression, perhaps because of maximum off-shelf transport from inter-reef areas or intermediate water dissolution. After accounting for siliciclastic dilution, there are strong similarities in both spatial and temporal patterns of carbonate minerals between slopes and basins of the north-east Australian margin and those of pure carbonate margins such as the Bahamas. A limited set of basic processes, including the formation and breakdown of carbonate on the shelf, the transport of carbonate off the shelf and eustatic sea level, probably controls carbonate accumulation in slope and basin settings of tropical environments, irrespective of proximal siliciclastic sediment sources.     

东海陆架盆地伸展率和压缩率及构造跃迁

东海陆架盆地位于欧亚板块的东南缘和西太平洋活动大陆边缘,本文选取了东海陆架盆地主要凹陷的17条地震剖面,采用平衡剖面技术,计算了主要凹陷新生代不同演化阶段的伸展率和压缩率。分析表明,东海陆架盆地构造演化总体由西向东跃迁。晚白垩世至晚古新世东海陆架盆地裂陷中心在西部坳陷带,始新世东迁至东部坳陷带,上新世东迁至东海陆架盆地东侧的冲绳海槽盆地。古新世中后期东海陆架盆地西部坳陷带北侧昆山凹陷反转;中新世东部坳陷带的西湖凹陷反转。东海陆架盆地西部坳陷带与东部坳陷带构造演化不同,证明了东海陆架盆地的东西分带。西部坳陷带北部的长江坳陷和南部的台北坳陷构造演化不同,东部坳陷带北部的西湖凹陷和南部的钓北凹陷构造演化不同,证明了东海陆架盆地的南北分块。     

The Early Devonian Coopers Creek Limestone: A deep‐water redeposited limestone in the Melbourne Trough,southeastern Australia

The Coopers Creek Limestone represents an Early Devonian redeposited carbonate accumulation and records the evolution of a carbonate slope in the southeastern portion of the Melbourne Trough. During the earliest Devonian, the underlying Boola Formation was deposited, probably as turbidites, in a moderately deep‐water setting. The presence of chert and greenstone clasts in the top of the formation indicates exposure of an area of Cambrian greenstones in this part of the Melbourne Trough, as a result of uplift associated with the earliest Devonian Bowning Orogeny. This uplift provided ideal conditions for carbonate production along the margin of the exposed landmass. The periodic transportation of carbonate material downslope resulted in the accumulation of the Coopers Creek Limestone. Initially, in the early Pragian, turbidity currents deposited clayey biomicrites and biopelmicrites on a relatively gentle slope. However, the rapid build‐up of carbonate sand banks at the shelf margin steepened the gradient from the shelf into the basin and a bypass margin began to develop. Grainflows deposited pelsparites and biopelsparites and the presence of debris flow breccias indicates erosion of lithified limestone by channelling. Continued carbonate build‐up led to the development of a rimmed reef margin in the earliest Emsian, with a steep fore‐reef gradient. Large blocks of reefal limestone fell or rolled to the base of the slope, to accumulate as reefal megabreccias at the top of the Coopers Creek Limestone. Carbonate production abruptly ceased in the early Emsian, due to the uplift of a quartzo‐micaceous source to the east during the initial stages of the Tabberabberan Orogeny. This uplift supplied abundant terrigenous material into the Melbourne Trough to be deposited as the turbidites of the Walhalla Group, which deeply buried the limestone accumulation.     

昆仑造山带二叠纪岩相古地理特征及盆山转换探讨

昆仑造山带基本构造-地层格架主要奠基于古生代,是早古生代和晚古生代多次洋陆转换、碰撞造山的结果。早中二叠世是晚古生代昆仑多岛洋盆(昆南洋)伸展裂陷最为强烈期,海相沉积广布,昆北为活动边缘裂谷,大部分区域为滨浅海相沉积,局部为火山盆地相沉积;昆中洋岛大部分为海水淹没,发育滨浅海相沉积;康西瓦—木孜塔格—阿尼玛卿一线及其以北昆南区为深海-半深海相沉积。早中二叠世总体表现为南深北浅的多岛小洋盆构造-古地理格局。中二叠世晚期昆仑地区发生了一次显著的汇聚作用(华力西运动),洋盆和活动大陆边缘裂谷闭合,隆升遭受剥蚀,完成了一次盆山转换。晚二叠世早期,大部分地区仍为剥蚀区,局部地区形成陆相红色碎屑岩建造,其后东昆仑东部海水从东南进入,西昆仑东部海水从西北进入,在较局限的区域内沉积了滨浅海相碎屑岩和碳酸盐岩沉积,进入了另一个盆山发展时期。笔者通过多年的野外观察、分析测试和综合研究,结合覆盖全区的1∶25万区域地质调查资料及其他前人研究成果,选择昆仑造山带晚古生代盆山转换关键时期——二叠纪,对其地层、岩相特征及构造古地理环境进行研究,并探讨了其构造演化,以期对提高昆仑造山带的研究水平和指导找矿工作有所禆益。     

Platform and off-platform carbonates of the Upper Cambrian of western Maryland, U.S.A.

Upper Cambrian carbonates in western Maryland are comprised of platform facies (Conococheague Limestone) west of South Mountain and basin facies (Frederick Limestone) east of South Mountain. Conocheague platform carbonates contain interbedded non-cyclic and cyclic facies. Non-cyclic facies consist of cross-stratified grainstones, thrombolitic bioherms, and graded, thin-bedded dolostones. These were deposited in shallow, subtidal shelf lagoons. Cyclic facies are composed of repeated sequences of cross-stratified grainstone; ribbon-rock; wavy, prism-cracked laminite; and planar laminated dolostone. The cyclic facies are shallowing-upward cycles produced by lateral progradation of tidal flats over shallow, nearshore subtidal environments. Cyclic and non-cyclic facies are interbedded in the Conococheague in a layer cake fashion, but no higher-order cyclicity can be found. The Frederick Limestone is dominated by monotonously thick sequences of graded, thin-bedded limestones, interbedded with massive peloidal grainstones and beds of breccia up to 10 m thick in the lower Frederick. The breccias contain transported megaclasts of Epiphyton-Girvanella boundstones. The basal Frederick was deposited in a slope-to-basinal setting east of a rimmed shelf. An Epiphyton-Girvanella marginal reef along the shelf edge was the source of the blocks in the breccias. The upper Frederick Limestone formed on a carbonate ramp.     

塔里木盆地西南缘齐姆根-桑株河地区石炭-二叠系沉积特征及沉积相

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．     

Depositional characteristics and constraints on the mid-Valanginian demise of a carbonate platform in the intra-Tethyan domain,Circum-Rhodope Belt,northern Greece

Two platform-type carbonate successions of Berriasian to early Valanginian age are exposed in the eastern Circum-Rhodope belt which extends from the Chalkidiki Peninsula to the Thrace region in northern Greece. On the basis of new sedimentological and biostratigraphic results and analysis of published palaeomagnetic data, the Porto Koufos Limestones and Aliki Limestones are interpreted as deposits of a formerly unknown earliest Cretaceous carbonate platform in the Western Tethys realm. This Circum-Rhodope carbonate platform existed in tropical latitudes of the intra-Tethyan domain on the northern shelf area of the small Vardar oceanic basin. It was characterized by limited regional extent, remoteness from land, and short lateral transitions into deeper basin areas. Predominantly skeletal sediments with various microencrusters were produced along with variable amounts of lime mud, marine cements, peloids, intraclasts, aggregate grains, ooids and microbialites. The microfacies analysis of limestones formed around the Berriasian–Valanginian boundary indicates the configuration of a rimmed shelf with restricted lagoon, open lagoon, reef margin, fore-reef and upper slope depositional environments. During the early Valanginian a change from photozoan to heterozoan mode of carbonate production occurred mainly as a result of climate cooling. Deposition continued in protected lagoon, shoal and near-shoal settings implying a ramp-like morphology of the platform. Finally, a shift from skeletal to non-skeletal carbonate deposition took place as a consequence of high seawater carbonate saturation and possibly coeval increase of the marine trophic levels. A major sea level fall and climate cooling were the prime palaeoenvironmental controls that caused decline of the shallow-water carbonate factory and subsequent demise of the Circum-Rhodope carbonate platform in mid-Valanginian time that was followed by a long-term subaerial exposure and karstification which continued at least until the middle Eocene. The new results can be used for correlation with other shallow marine carbonates deposited in the intra-Tethyan domain during the earliest Cretaceous. Also, they appear to be of critical significance to decipher the Mesozoic geodynamic evolution of the Circum-Rhodope belt and adjacent tectonic zones.     

塔里木盆地上白垩统依格孜牙组碳酸盐岩沉积学特征及地质意义

塔里木盆地西南缘沿西昆仑山前白垩系上统依格孜牙组沉积巨厚的碳酸盐岩，分布范围西至喀什，东至叶城县克里阳地区，主要岩相有以生物碎屑灰岩为主8种岩相，碳酸盐岩主要由亮晶鲕粒灰岩和高晶生物碎屑灰岩组成；沉积环境以台地边缘、开阔台地相、局限台地相为主；沉积环境自东向西由台地边缘-开阔台地相-局限台相演变；厚度在西向东由125m减薄至10m；巨厚的碳酸盐岩沉积可以划分7个米级旋回，7个米级旋回的碳酸盐岩沉积组成了塔里木盆地西南缘白垩系新的油气勘探目的层系，丰富的牡蛎、蛤、螺等化石，稳定的台地相、礁滩相台地边缘相沉积，说明当时塔里木盆地西南缘为向西北开口的海域，古气候温暖，古盐度为半咸到咸水；海域古地理西边与塔吉克相通，东边至叶城县克里阳地区，沿昆仑山前呈显一峡长条带。