数字高程模型在天津滨海平原区地质填图中的应用

天津市滨海平原地区地势平坦,地貌类型不易划分,沉积物粒度较细,遥感解译精度及实地可识别性差,按照传统的地质调查方法开展填图,图面表达效果不佳。数字高程模型(Digital Elevation Model, DEM)是地形的数字化表达,具有一般地形图无法表达的三维可视化信息,能够真实反映地形地貌特征。在开展天津滨海平原地质填图过程中,通过建立研究区DEM,并结合路线地质调查、槽型浅钻施工、样品测试分析,进行了地貌单元划分,将浅地表沉积物划分为河流、海侵和三角洲3个沉积体系: 河流沉积体系包含边滩(曲流砂坝)、充填河槽(牛轭湖)、决口扇、天然堤、洪泛盆地和湖沼沉积微相; 海侵沉积体系包含海滩脊、越岸扇、高潮坪和残留潟湖沉积微相; 三角洲沉积体系主要为三角洲前缘沉积。通过与不同类型遥感解译结果进行对比分析可知,DEM可充分弥补遥感影像的不足,对浅地表沉积物进行详细的成因类型划分,提升对浅地表地质作用过程的认知程度,较好地指导野外地质填图。将高精度DEM数据应用于第四系覆盖区地质填图,可以大大提高填图精度及效率,为城市生态安全保障、国土空间规划、产业结构布局等提供基础地质依据。     

柴达木盆地西部地区古近纪与新近纪沉积相

利用数十口井的电性、岩性及分析化验资料，将柴达木盆地西部地区古近纪与新近纪沉积相划分为七种相和亚相：洪积锥、水下冲积扇、河道和泛滥平原、滨湖、浅湖、较深湖和三角洲。沉积相的空间展布概括起来分为三大带：（1）阿尔金山前西段陡坡带洪积锥-水下冲积扇-扇三角洲-河道和泛滥平原-湖相 (2)阿尔金山前中段陡坡带洪积锥-水下冲积扇-湖相；（3）昆仑山前洪积锥-河道和泛滥平原-三角洲相。沉积相不仅影响着碎屑岩的成分和结构，而且也影响其物性与含油性。由洪积锥到水下冲积扇，到河道和泛滥平原，到三角洲，到湖相，石英和胶结物含量逐渐升高，岩屑和杂基含量逐渐降低，分选及磨圆变好，颗粒的粒级变细。浅层以河道和泛滥平原及三角洲相的物性最好，深层以三角洲相的物性最好，次为冲积扇，湖相最差。碎屑岩的油气富集以河道、泛滥平原和三角洲相最好，滨浅湖相油气富集最差。     

二连盆地吉尔嘎朗图凹陷下白垩统赛汉塔拉组层序地层及聚煤特征

二连盆地吉尔嘎朗图凹陷是一个陆相断陷聚煤盆地,下白垩统赛汉塔拉组是其主要含煤地层,作者利用岩心、钻孔资料对其岩相类型、沉积相、层序地层及聚煤作用特征进行研究。(1)赛汉塔拉组主要由砂砾岩、砂岩、粉砂岩、泥岩、碳质泥岩及厚层褐煤组成,发育扇三角洲平原相、扇三角洲前缘相、辫状河三角洲平原相、辫状河三角洲前缘相、滨浅湖相,分别属于扇三角洲沉积体系、辫状河三角洲沉积体系和湖泊沉积体系。(2)识别出2种层序界面:不整合面和下切谷冲刷面,将赛汉塔拉组划分为2个三级层序。从层序Ⅰ到层序Ⅱ,煤层厚度逐渐增大,聚煤作用逐渐增强。(3)在滨浅湖环境下厚煤层主要形成于湖侵体系域早期,在扇/辫状河三角洲环境下厚煤层主要形成于湖侵体系域晚期,煤层厚度在凹陷中部最大,向西北和东南方向均变小。聚煤作用明显受基底沉降作用影响,可容空间增加速率与泥炭堆积速率相平衡,从而形成了区内巨厚煤层。     

鄂尔多斯盆地上三叠统延长组长9油层组沉积相及其演化*

鄂尔多斯盆地延长组长9油层组发育三角洲—湖泊沉积相,三角洲平原分流河道砂体和三角洲前缘水下分流河道砂体是最有利的储集砂体。在沉积相研究的基础上,根据单因素分析多因素综合作图法,选取了地层厚度、较深水沉积岩含量、砂岩厚度、砂地比、自生绿泥石分布、古生物化石分布和沉积构造分布等单因素,对鄂尔多斯盆地延长组长9油层组上下2段的沉积相平面展布特征进行了深入研究,并探讨了其演化规律。研究表明,鄂尔多斯盆地以发育多水系、多物源注入的环湖分布的多个三角洲为特色,东北部地区主要发育曲流河三角洲,西部发育辫状河三角洲,其中以三角洲平原分流河道和三角洲前缘水下分流河道微相较为发育。长9₂沉积期,半深湖沉积在盆地内较为局限,长9₁沉积期湖盆初始扩张达到最大范围,湖岸线向陆推移,湖域面积扩大,半深湖沉积较发育。由长9₂沉积期到长9₁沉积期,鄂尔多斯盆地沉积水体经历了由浅变深的过程,由此在长9₂的顶部沉积了一套具有生烃潜力的油页岩。     

利用测井曲线判识鸳鸯湖矿区成煤环境及沉积类型

根据以往钻孔及其测井资料,对鸳鸯湖矿区早-中侏罗世延安期的沉积环境及沉积类型进行了划分：即垂向正层序湖泊三角洲平原相沉积与反层序的三角洲前缘相、湖湾相沉积。前者表现为浅湖泊三角洲的推进,后者表现为浅湖泊三角洲的废弃。其中三角洲平原相沉积类型包括分流河道天然堤沉积组合,决口扇泛滥平原沉积组合,以及泥炭、沼泽沉积组合;三角洲前缘相沉积类型包括河口坝沉积（近端坝、远端坝）、水下分流河道沉积、水下天然堤、分流间湾沉积。通过对比各种沉积组合在自然伽马、视电阻率等测井曲线形态上的反映特征,指出测井曲线异常形态能够反映本区的沉积旋回,并以此总结出了鸳鸯湖矿区的成煤环境、沉积旋回的划分及聚煤规律。     

Fluvial shoal water deltas: pre-vegetation sedimentation through the fluvial–marine transition,Lower Cambrian,English Channel region

Lower Palaeozoic fluvial systems tend to be more sand-prone than those of later eras and the nature of coastal environments less certain. Field studies are presented that characterize the fluvial to marine transition over a distance of 80 km, in the Lower Cambrian of the Cotentin Peninsula, northern France. The sedimentary rocks are divided into six facies associations which represent deposition in proximal fluvial, distal fluvial, delta plain, delta front, pro-delta and offshore carbonate bank environments. The basin fill is sandstone-dominated and subdivided into three stratigraphic intervals. A 200 to 300 m thick basal interval contains very coarse-grained fluvial sandstones deposited during a relative sea level lowstand. An overlying interval, 250 to 1500 m thick, is a facies mosaic. Fluvial strata in the north-west pass laterally south-east into deltaic and shallow marine pro-delta sediments. The delta front deposits show repetitively stacked, upward-coarsening parasequences, 8 to 10 m thick, which reflect the repeated progradation of lobate, fluvially-dominated deltas onto a shallow marine shelf. The deltas formed following marine transgression and accumulated during a period of gradually rising relative sea level. An upper unit, 130 m thick, containing offshore stromatolitic and oolitic limestones, caps the study interval and represents deposition during a relative sea level highstand. The fluvial and delta distributary channel sandstones of the middle unit contain <1% mudstone. The cohesionless substrate determined that deltaic distributaries were predominantly braided in character and subject to common bifurcations which resulted in an ordered diminution of channel size and competence in a seaward direction. Terminal distributary channels show evidence of migratory levées and mouth-bars and consistently delivered fine to medium-grained sand to the delta front. The study highlights an example of pre-vegetation deltaic sedimentation that was hydraulically organized and predictable, despite being fed by braided fluvial systems with high levels of peak discharge.     

川西前陆盆地上三叠统沉积特征

应用层序地层学方法将川西前陆盆地上三叠统划分为4个三级层序和12个体系域。在层序格架内,研究了不同时期的古地理背景、物源、沉积类型和沉积相展布,明确了上三叠统存在龙门山古陆、米仓山-大巴山古陆、康滇古陆、江南古陆4个物源,识别出上三叠统海湾、冲积扇、曲流河、辫状河、扇三角洲、辫状河三角洲、曲流河三角洲和湖泊8种沉积相类型。层序Ⅰ沉积时期,盆地处于海陆交互相向陆相转变的时期,整体具有填平补齐的沉积特征,发育海湾等沉积;层序Ⅱ沉积时期,川西前陆盆地成为统一的内陆湖盆,其湖侵期为须家河期最大的湖侵期,主要发育三角洲沉积和湖相沉积;层序Ⅲ沉积时期,米仓山-大巴山古陆提供充足的物源,在米仓山-大巴山两逆冲推覆带前缘广泛发育大型冲积扇、辫状河、辫状河三角洲沉积体系;层序Ⅳ沉积时期,主要受江南古陆的影响,发育三角洲沉积和湖泊沉积。整体上,川西前陆盆地沉积相带的展布格局受构造控制,具有平行构造带展布的特点。盆地西北部陡坡带发育粗粒的冲积扇、扇三角洲-湖底扇,西南部陡坡带发育辫状河三角洲、北部-东北部陡坡带发育辫状河三角洲,而在东南部缓坡带则发育远源的曲流河、曲流河三角洲。     

昆明盆地两孔岩芯的沉积特征及环境磁学分析

本文根据比较密的采样和磁化率测量,结合沉积特征、生物化石和沉积速率,分析了不同沉积环境沉积物的磁化率数值及沉积相变所表现出的磁化率曲线的形态特征.     

Construction and application of coastal zone image map based on uncontrolled point technology

Using the tight connection of direct geolocation technique and large-scale digital aerial photography system, the authors carried out the high-precision aerial remote sensing survey in Binhai New Area of Tianjin and Caofeidian New Area of Tangshan, West Bohai Bay. The application of uncontrolled point technology gets rid of the dependence on the base station for aerial remote sensing, and also overcomes the shortcoming of the rarity of ground stations in the surrounding areas of the coastal zone. Utilizing the 0.3 m high-resolution true-color aerial photography images and high-precision positioning and orientation elements, the authors have successfully constructed the Digital Elevation Model (DEM) and Digital Orthophoto Map (DOM), which meet the requirements of 1:10 000 scale indexes in plane and altitude. These fill the gap in the basic geological information of high-precision aerial remote sensing in Binhai New Area and the intertidal belt of Caofeidian Coastal Zone. On the basis of high-resolution satellite data, remote sensing interpretation has been used for land type classification and coastline extraction, which provides detailed and reliable geographic information for the thematic maps of remote sensing geological interpretation, geological ecological environment and disasters. The results show that the application of tightly coupled airborne position and orientation system (POS) and uncontrolled technology shortens the mapping cycle of DEM and DOM, reduces a lot of ground measurement workload and saves manpower and material expenditure. The research can provide some new technical support and working ideas for geological survey in coastal zone working areas.     

基于无控技术的海岸带影像图构建与应用

运用直接地理定位技术和大幅面航空数字摄影系统的紧密捷联,开展渤海湾西部天津滨海新区和唐山曹妃甸新区的高精度航空遥感调查工作。无地面控制点技术的应用摆脱了航空遥感对基站的依赖,也克服了海岸带周边地区地面基站稀少的局限。利用获取的0.3 m高空间分辨率真彩色航摄影像和高精度定位定向元素,成功构建了平面与高程均符合1:10 000比例尺指标要求的数字高程模型(digital elevation model,DEM)和数字正射影像图(digital orthophoto map,DOM),填补了天津滨海新区和唐山曹妃甸新区海岸带潮间带高精度航空遥感基础地质信息的空白,同时结合高分卫星数据,在土地类型分类、海岸线提取等方面开展了遥感解译应用,为进行遥感地质解译、地质生态环境与灾害等要素的专题图制作提供详实可靠的地理信息基础数据。研究结果显示,紧耦合机载定位定向系统(position and orientation system,POS)无控技术的运用缩短了DEM和DOM成图作业周期,减少了大量地面测量工作,节约了人力和物力支出,为海岸带工作区开展地质调查提供了新的技术支撑和工作思路。     

湖泊细粒沉积特征精细研究：以鄂尔多斯盆地延河剖面长7油层组为例

野外地质露头为精细刻画沉积体内部结构、建立准确地下地质模型发挥着重要作用。以鄂尔多斯盆地延河剖面长7段为例,采用岩石学、野外露头沉积学方法,详细剖析了湖泊细粒沉积的岩相类型、特征、垂向组合及沉积环境。研究结果表明,延河剖面长7段发育平行层理细砂岩相、流水交错层理细砂岩相、浪成交错层理粉砂岩相、沙纹层理粉砂岩相、变形层理粉砂岩相、水平层理(泥质)粉砂岩相、块状泥岩相、水平层理(砂质)泥岩相、水平纹层页岩相9种岩相类型。在结合区域地质特征基础上,研究认为长7段为远源的曲流河三角洲前缘和浅湖-半深湖沉积,进一步细分出7类沉积单元,其中水下分支河道、支流间湾较为发育,水下天然堤、远砂坝、席状砂发育规模较小,浅湖-半深湖沉积只在长72段下部发育,河口坝基本不发育,仅局部可见。对各沉积单元的垂向分布特征进行深入研究,识别出Ⅰ、Ⅱ、Ⅲ、Ⅳ 4类垂向分布形式,其中Ⅰ、Ⅱ组合主要分布在研究区长71、长73亚段,Ⅲ、Ⅳ组合主要分布在研究区长72亚段。剖面相分析表明,长7沉积期整体为一套先变细、再变粗的细粒沉积序列,为曲流河三角洲前缘沉积—浅湖-半深湖沉积—曲流河三角洲前缘沉积。     

现代乌伦古湖滨岸沉积环境与沉积体系分布及其控制因素

通过现场实地踏勘、拍照、开挖探槽、利用卫星图解译等方法,对乌伦古湖环布伦托海区域和吉力湖北部乌伦古河现代三角洲地区的湖泊滨岸沉积环境和沉积体系进行了现代沉积调查。研究表明乌伦古湖滨岸沉积环境可以划分为基岩型湖岸、砾质湖岸、砂质湖岸、泥质湖岸等4种类型,发育山前基岩型湖岸、侵蚀基岩型湖岸、砾质冲积扇-扇三角洲、砾质辫状河三角洲、砾质滩坝、砂质滩坝、砂质三角洲、风成沙丘和泥质沼泽等9种滨岸沉积体系。山前基岩湖岸分布在布伦托海的北部,主要发育小型塌积扇、倒石锥和狭窄的湖滩。侵蚀型基岩湖岸位于布伦托海西岸和东北角地区,发育湖滩宽20~40 m。砾质冲积扇-扇三角洲沉积体系分布在布伦托海西北部25.8 km狭长区域,表现为一系列冲积扇-扇三角洲体系在山前形成裙边状展布的辫状平原,顺流向长5~15 km。砾质辫状河三角洲体系发育在布伦托海西部,砾质滩坝发育在砾质三角洲前缘,沉积物一般为中砾和粗砾,泥质含量低。现代乌伦古河三角洲位于吉力湖北部,沙丘广泛分布在布伦托海东部的三角洲平原。砂质滩坝发育在布伦托海东岸南部地区,滩坝带宽30~100 m,发育大量障碍痕、冰划痕。泥质沼泽占据湖岸总长度29.22 km,沼泽地带植物繁茂,水动力微弱,泥质和有机质含量高。根据卫星照片推测乌伦古湖水位可能发生过3次较大的下降,现代乌伦古河三角洲可能经过了4个发育阶段,但目前缺乏地质年代学证据。构造格局控制了湖泊边界的地形地貌特征,平行构造线走向容易形成规模较大的沉积体系,垂直构造走向形成的沉积体系规模较小。寒旱地区湖泊周缘入湖河流较少,具有季节性和暂时性特点,洪水泥石流、塌积扇等重力沉积体系比较发育。湖泊封冻是寒旱区湖泊区别于温暖地区湖泊的重要特征。在相同气候背景下,源汇地区的高差和河流的流程、流量决定了沉积物的供给总量和沉积体系的特征。湖盆边界形态影响沿岸流的发育,也影响湖泊风动力方向和强度。乌伦古湖滨岸沉积体系的多样性对研究古代湖泊滨岸沉积体系具有重要的启发,开展湖泊滨岸沉积环境和沉积体系调查对完善陆相湖盆沉积体系模式,对发现新的储层类型,对重建湖泊古地理环境具有重要的意义。     

Cretaceous Sandbody Characters at Shallow‐Water Lake Delta Front and the Sedimentary Dynamic Process Analysis in Songliao Basin,China

Based on the abundant information from drilling, cores, and logging, the influence of topography, size of rivers and lakes, climate changes and the lake level’s fluctuation on the sandbodies at shallow-water delta front are systematically summarized and the sedimentary dynamic processes are analyzed. The interwell communication among the sandbodies and their planar distribution revealed from the hydrodynamic features of the development wells are integrated during the analysis. The fundamental requirements for the development of the shallow-water delta included flat topography and uniform subsiding rate. The delta plain was connected smoothly with the wide delta front and predelta, without the three-fold structure of topset, foreset, and bottomset as defined in the Gilbert Delta Model. Because of the weak fluvial effect and the lake energy is strong, the small and scattered shallow-water delta is destroyed by the scouring-backwashing, coastal current, and lake wave, resulting in the coastal sheet deposition. As the fluvial effect became stronger and the lake energy became weaker, the shape of the shallow-water deltas transferred from sheets to lumps and then branches.     

鄂尔多斯盆地及周缘地区下二叠统沉积特征

通过大量的野外剖面观察和盆地内钻井岩心的详细描述,综合测井资料,从岩石类型、结构、沉积构造、古生物化石及测井曲线响应特征等方面对鄂尔多斯盆地及周缘地区下二叠统太原组和山西组沉积相特征进行了全面分析研究。结果表明,太原组主要发育陆棚、海岸、冲积扇和三角洲等沉积相,海岸沉积相包括障壁岛、潟湖和潮坪沉积,三角洲沉积相可划分为三角洲平原、三角洲前缘和前三角洲沉积。山西组主要发育冲积扇、河流、曲流河三角洲、湖泊和海岸沉积相,其中河流沉积相包括辫状河和曲流河沉积,曲流河三角洲沉积相可划分为曲流河三角洲平原、曲流河三角洲前缘和前三角洲沉积,而湖泊沉积相以浅湖沉积为主,海岸沉积主要为潟湖沉积。太原期,海相沉积占主导,主要分布于银川-榆林北部一线以南广大地区,并且从东西两侧至中部地区由浅海陆棚沉积和滨浅海过渡为潟湖沉积和潮坪沉积,其间发育障壁岛。盆地西北缘发育冲积扇和扇三角洲沉积,北部广大地区以三角洲沉积为主,自北向南依次为三角洲平原和三角洲前缘沉积。山西期,海水从盆地东南部退却,整体演变为海陆过渡相沉积,盆地北部乌达-杭锦旗-鄂尔多斯一线发育冲积扇沉积,向南至靖边一带依次发育辫状河和曲流河沉积,靖边以南至延安以北地区以三角洲平原沉积为主,向南至同心-庆阳一线发育三角洲前缘沉积,盆地南部彭阳-泾阳地区主要为浅湖沉积,再向南发育物源来自南部的三角洲沉积,在东南部武乡-义马一带为潟湖沉积。     

基于数字填图系统的遥感等数据在构造-地层分区和地层单位识别中的应用——以1：25万民和县幅、临夏市幅和定西市幅数字地质填图为例

在甘肃和青海交界地区的1：257Y民和县幅、临夏市幅和定西市幅数字区域地质调查中,以“数字填图系统（RGMAP）”为平台,使用遥感ETM^＋数据和地形数据对岩石地层进行了信息挖掘。数据准备主要是遥感和数字地形多源信息的提取和预处理．从数字地形图的等高线数据中提取高程,进而提取汇水网络等水文信息和地形参数。遥感数据经过地形校正、线性增强、色彩拉伸,进行空间分辨率增强,经彩色合成并结合数字高程,实现了对调查区构造-地层区划和部分岩石地层单元的识别。实践证明该项工作是地质填图的重要辅助手段。     

鄂尔多斯盆地及周缘地区下二叠统沉积特征*

通过大量的野外剖面观察和盆地内钻井岩心的详细描述,综合测井资料,从岩石类型、结构、沉积构造、古生物化石及测井曲线响应特征等方面对鄂尔多斯盆地及周缘地区下二叠统太原组和山西组沉积相特征进行了全面分析研究。结果表明,太原组主要发育陆棚、海岸、冲积扇和三角洲等沉积相,海岸沉积相包括障壁岛、潟湖和潮坪沉积,三角洲沉积相可划分为三角洲平原、三角洲前缘和前三角洲沉积。山西组主要发育冲积扇、河流、曲流河三角洲、湖泊和海岸沉积相,其中河流沉积相包括辫状河和曲流河沉积,曲流河三角洲沉积相可划分为曲流河三角洲平原、曲流河三角洲前缘和前三角洲沉积,而湖泊沉积相以浅湖沉积为主,海岸沉积主要为潟湖沉积。太原期,海相沉积占主导,主要分布于银川—榆林北部一线以南广大地区,并且从东西两侧至中部地区由浅海陆棚沉积和滨浅海过渡为潟湖沉积和潮坪沉积,其间发育障壁岛。盆地西北缘发育冲积扇和扇三角洲沉积,北部广大地区以三角洲沉积为主,自北向南依次为三角洲平原和三角洲前缘沉积。山西期,海水从盆地东南部退却,整体演变为海陆过渡相沉积,盆地北部乌达—杭锦旗—鄂尔多斯一线发育冲积扇沉积,向南至靖边一带依次发育辫状河和曲流河沉积,靖边以南至延安以北地区以三角洲平原沉积为主,向南至同心—庆阳一线发育三角洲前缘沉积,盆地南部彭阳—泾阳地区主要为浅湖沉积,再向南发育物源来自南部的三角洲沉积,在东南部武乡—义马一带为潟湖沉积。     

黄河三角洲进积与滨海湿地地质环境演替模式

本文通过对黄河三角洲5个钻孔岩芯的沉积学观测、微古分析、14C测年,同时结合历史记录及遥感资料,分析了本区末次冰后期以来的沉积序列,重建了近10ka以来古环境演变过程,分析了古环境演化对滨海湿地演替的控制作用。本文着重讨论了黄河三角洲进积与湿地形成演替规律,总结了从水生系统、浅海湿地系统、潮滩湿地直至上三角洲平原湿地向陆地生态系统的演替模式。同时通过对现代黄河三角洲与老黄河三角洲演化模式进行对比,提出气候变化、人类活动会加速和改变湿地地质环境演替进程和方向的一般规律。笔者等还进一步提出,由于人类活动的影响,1855年之后湿地演替速率明显加快,约达8~33倍。古环境的重建与滨海湿地响应机制研究可更清楚地理解湿地如何对未来环境变化进行响应,包括海平面上升,从而为滨海湿地保护与管理实践活动提供科学导向。     

Review of the chronostratigraphic charts in the Sinú-San Jacinto basin based on new seismic stratigraphic interpretations

Disperse and punctual studies; absence of integration of data ranging from local to regional focus; interpretations based only on lithostratigraphic features; and interpretation of data premised on an allochthonous origin of the Caribbean plate, are some of factors that increase the confusion and uncertainty in understanding the Sinú-San Jacinto Basin. The sedimentary record of Upper Cretaceous to Eocene has been traditionally interpreted as the record of deep-water settings. However, recently these sediments have been related to shallow marine and deltaic settings. Second problematic point is about the deposition environment of the Oligocene to Late Miocene succession. Some studies suggest canyons, turbidites and sediments deposited in deep-water settings. However, recent studies propose deltaic and shallow marine settings. The last stratigraphic problem is related to the controversial fluvial vs. shallow marine interpretations of the Pliocene sediments. Based upon seismic stratigraphic analysis in recent and reprocessed 2D seismic data, integrated with well data, we propose chronostratigraphic charts for the northern, central and southern zones of the Sinú-San Jacinto Basin. Twenty seismic facies based on amplitude, continuity, frequency and geometry of seismic reflectors and twelve seismic sequences were recognized. The seismic stratigraphic analysis in this study suggests that the sediments of Upper Cretaceous to Paleocene/Eocene were associated to continental to shallow marine settings. Lagoons, coastal plain and carbonate platform dominated during this period. The Oligocene to Middle Miocene record was characterized by deep-water deposition, whereas the Late Miocene to recent sedimentation was characterized by falling base level, characterized by deltaic and fluvial deposits. Five syn-rift sequences with wedge-shaped geometry were identified in this study. Three Triassic to Jurassic syn-rift sequences were characterized by seismic facies typical of fluvial to lacustrine and flood plain sedimentation. Two Cretaceous to Paleocene syn-rift sequences were characterized by seismic facies related to lagoons to coastal plain settings. Normal high-angle faults with a northeast-southwest direction related to rifting processes controlled the development of these sequences. The sheet-drape post-rift section was characterized by passive margin settings in the northern part of the Sinú-San Jacinto Basin and by diachronic tectonic inversion of older normal faults during Cenozoic, predominantly in the central and southern zones. The stratigraphic record related to the Mesozoic to Early Cenozoic rifting; the shallow marine sedimentation during Eocene and the tectono-stratigraphic continuity across the northern Colombia and northwestern Venezuela is coherent and well explained by the in situ origin of the Caribbean plate and is not explained by the “allochthonous” model.     

中国现代网状河流沉积特征和沉积模式

中国境内的许多河流发育有网状河段,从长江、黑龙江、珠江等这样的大型河流到嫩江、赣江等中小型河流都有。依据这些网状河的地理和构造背景的不同,可以把它们划分为:平原网状河流、山谷网状河流、入湖三角洲平原网状河流和入海三角洲平原网状河流四大类型。作者通过实地挖掘探槽、密集采样,对嫩江齐齐哈尔平原网状河段、赣江入湖三角洲平原网状河段、珠江入海三角洲平原网状河段沉积特征进行了详细描述和研究,并建立了网状河的沉积模式,探讨了网状河的成因。认为网状河流体系的发育不受气候和地理位置的限制,低坡降是形成网状河的必要条件,相对稳定的网状河道不同于曲流河和辫状河,湿地环境是网状河流体系中最发育的地貌单元,堤岸植被繁茂、粘结性高是河道稳定的重要因素,与曲流河和辫状河相比,网状河出现的几率较低。     

广西百色盆地东部古近系那读组湖相灰岩

百色盆地东部田东坳陷那坤地区古近系那读组三段下部发育一套数米至数十米厚的湖相灰岩,岩石以浅灰色-灰色、含大量的螺蚌化石和具核形石结构为特征,间夹有薄层的泥岩、钙质泥质粉砂岩。本文在实测地表剖面和详细观察岩心的基础上,仔细研究了此套灰岩的岩石学特征。依据丰富的原生沉积构造、古生物化石标志以及沉积地球化学、测井相特征将湖相灰岩的沉积相划分为滨湖、颗粒滩、浅湖三个亚相以及灰泥坪、沼泽、颗粒坪、滩缘、滩核、滩间水道、灰泥浅湖、泥质浅湖等八个微相,并详细地研究了各微相的沉积特征。结合该灰岩的区域分布和沉积相的平面展布格局指出沉积相主体属于浅湖的颗粒滩,并提出了相应的沉积相模式。