Quaternary reactivation of a basement structure in the Barreirinhas Basin, Brazilian Equatorial Margin

The Pirapemas Lineament is a remarkable 200-km-long, NE-SW trending structure in the Barreirinhas Basin, one of the several Brazilian coastal basins. This lineament splits the study area in two sectors of distinctive morphology, drainage patterns, and sedimentary covers. Terrain northward of the lineament presents a smooth topography with sub-parallel to sub-dendritic drainage patterns, whereas a dissected plateau characterized by incised valleys and rectangular drainage pattern occurs southward, suggesting a structural control by joints and faults. Geological field data, crossed with thermal luminescence (TL) and optically stimulated luminescence (OSL) dating, revealed that the surface southward of the lineament consists mostly of Miocene and late Pleistocene sedimentary deposits, represented by the Barreiras Formation and the Post-Barreiras sediments, respectively. In contrast, relatively younger sands mantle most of the northward terrain, as indicated by well-preserved paleodune deposits that grade into active aeolian dunes of the Lençóis Maranhenses National Park. Geomorphological and geological data analysis suggests that the northern sector is under the effect of subsidence, proving that the Pirapemas Lineament is an active agent modeling the landscape in the region. Geophysical data (gravity and seismic) confirm that such a structural feature is the surface expression of an active deep-seated basement fault.     

塔里木盆地下志留统塔塔埃尔塔格组沉积体系及沉积模式

通过对塔里木盆地众多野外剖面详细观测及钻井岩心的详细观察,研究区下志留统塔塔埃尔塔格组主要沉积一套以砂、泥岩为主的碎屑岩,根据岩性特征、生物标志和地球物理特征,将塔里木盆地塔塔埃尔塔格组划分为滨岸和陆棚沉积体系,滨岸沉积体系进一步划分为无障壁海岸和有障壁潮坪沉积,陆棚沉积体系以浅水陆棚沉积为特征,并就各微相的岩石类型、粒度分布和沉积构造特征进行了详细的研究。在此基础上,分析了塔塔埃尔塔格沉积期的平面展布特征,总体格局为南北向分带,东西向展布为特征。同时建立了塔里木盆地塔塔埃尔塔格组滨岸、潮坪和滨岸－潮坪的沉积模式,在研究区以滨岸－潮坪的沉积模式为主。     

西藏沙丁、荣布地区三叠系—老第三系沉积地质特征

研究区从三叠纪到老第三纪,发育的岩石地层主要有确哈拉群（Ｔ３）、希湖群（Ｊ１－２）、拉贡塘组（Ｊ２－３）、多尼组（Ｋ１）、竟柱山组（Ｋ２）和牛堡组（Ｅ２－３）。在沉积相上,经历了从深水沉积到浅水直至陆相沉积的演变,发育有冲积扇、河流、湖泊、三角洲（潮汐）、障壁海岸、浅海、深海和火山碎屑流沉积。古地理分析表明,研究区晚三叠世古地理轮廓是一个从东南向西北和东北方向由浅水碳酸盐台地及深水陆层海底扇沉积共同发育的沉积盆地;早中侏罗世,演变成为一个由深水砂质浊积岩和细屑浊积岩组成的水下席状体沉积;进入中晚侏罗世,其古地理表现为一个陆屑浅海有障壁海岸;到了晚白垩世,研究区表现为以含煤沉积为特征的三角洲相沉积。     

Did glaciers exist during Pleistocene in the Midyan region, northwest corner of the Arabian Peninsula?

Spectacular erratic boulders, polymictic conglomerates, and sedimentary structures are discovered in many localities at the Midyan Peninsula, east of the Gulf of Aqaba. These deposits are discontinuous, and they unconformably overlie older lithological units of Proterozoic, Cretaceous, Paleogene, and Neogene ages. The erratic boulders are composed of basement rocks, sandstone, and limestone. Some of the boulders exceed 2?m (6?ft) in diameter. The boulders are sub-rounded to rounded, striated, polished, grooved, and faceted. The polymictics are composed of heterogeneous coarse clastics (ranging from boulders to conglomeratic sandstones) of various rock types and fill incised paleovalleys. The sedimentary structures include polished, faceted, and striated boulders, pavements, U-shaped valleys, slumps, and fan-shaped structures. These deposits are herein informally named the Midyan Formation. A Pleistocene age is assigned to the formation based on its stratigraphic position. The polymictic conglomerates are interpreted as glaciogenic tillite, and the erratic boulders and sedimentary structures are considered to have been deposited by glacial erosion, deposition, and possibly tectonics. This interpretation raises the question; did glaciers exist during Pleistocene in the Midyan region? If this interpretation is valid, then recognition of Pleistocene glaciation in Arabia fills a blank spot in the global map of the ??Ice Age??. Pleistocene glacial features were reported in Yemen and regions in north Iraq.     

Geology of Neogene basins of Buldan-Sarıcaova region and their importance in Western Anatolia neotectonics

The Büyük Menderes and Gediz (Ala?ehir) grabens are two significant segments of the Western Anatolian extensional province. They merge around Buldan-Sar?caova in the east. Outcropping Neogene sedimentary units in this area display a rather complex structure. This paper summarizes the importance and meaning of the data obtained during a detailed investigation of the Neogene units and aims to improve our understanding of the neotectonic evolution of Western Anatolia. The Buldan-Sar?caova Neogene sequence is composed of three different sedimentary units: (1) the Lower Unit, (2) the Middle Unit, and (3) the Upper Unit. The Lower Unit crops out on the Buldan horst which is located between the Büyük Menderes and Ala?ehir grabens. The sequence starts as a coarse conglomerate and sandstone (?salar Formation) and continues as lagoonal-lacustrine mudstone, interbedded with coal seams and shales (Bostanyeri Formation) and also with lacustrine limestones. The age of this succession is Lower-Middle Miocene. The development of the basin is structurally controlled by NNW-trending normal faults. The Middle Unit begins with a conglomerate–mudstone sequence (K?z?lburun Formation), followed by a sandstone–mudstone–marl sequence (Sarayköy Formation). A lacustrine limestone–marl unit occurs at the top (Aktepe Formation). Some thin gypsum lenses and layers are observed in the Sarayköy Formation. The unit contains some brackish-water fossils. The rocks of the Middle Unit crop out mostly at the low altitudes of the Buldan horst, i.e. the southeast piedmont, around the junction of the Büyük Menderes and the Gediz grabens. The Middle Unit was deposited in fluvial and lacustrine environments during the Late Miocene–Pliocene period. These rocks were formed in response to the uplift of the Buldan horst. The Upper Unit, which is composed of conglomerates, was deposited within the Büyük Menderes Graben–Gediz Graben depressions as alluvial fill.     

埕宁隆起北坡新近纪沉积特征及发育模式

综合运用岩心观察、薄片鉴定、测井、地震等分析方法和手段,对埕宁隆起北坡新近系馆陶组-明化镇组沉积相进行了系统研究。结果表明,研究区新近纪馆陶组-明化镇组发育辫状河和曲流河沉积,主要沉积微相有河床滞留、心滩、边滩、天然堤、决口扇及泛滥平原等。在相分析的基础上,进一步研究了区内沉积微相的平面展布特征及其演化规律,认为区内馆陶期为辫状河,明化镇组演化为曲流河。在此基础上,建立了埕宁隆起北坡新近系馆陶期-明化镇期的沉积模式,并探讨了不同模式下储集砂体的分布规律。     

新疆拜城新近系含铜岩系沉积体系及沉积环境

新疆拜城地区发育一套新近纪巨厚的陆相碎屑沉积岩系,其中康村组中上部含规模较大的沉积型铜矿,康村组的沉积环境及演化过程对铜矿的形成具有重要意义。基于野外和室内详细的沉积学研究,查明研究区新近系吉迪克组、康村组和库车组总体上为陆相沉积体系,主要包括冲积扇-扇三角洲沉积体系和湖泊沉积体系两大类型,划分为扇三角洲平原、扇三角洲前缘、前扇三角洲、滨浅湖和膏盐湖亚相及若干沉积微相。研究表明研究区康村期主要发育扇三角洲沉积,矿区主要含矿层位于康村组上部红色岩系向灰色岩系转变,沉积环境从扇三角洲前缘亚相到滨浅湖亚相过渡的层位上。     

SEDIMENTARY PROCESS OF THE CENOZOIC BASIN AND ITS RESPONSE TO THE SLIP-HISTORY OF THE ALTYN TAGH FAULT, NW CHINA

SEDIMENTARY PROCESS OF THE CENOZOIC BASIN AND ITS RESPONSE TO THE SLIP-HISTORY OF THE ALTYN TAGH FAULT, NW CHINAtheprogramsof ( 1)theYoungGeologistsFoundationoftheMGMR (No .Qn979812 ) ;;( 2 )theNational (No .G19980 4 0 80 0 ) ;;and ( 3)the     

Sedimentology,stratigraphy and palynological occurrences of the late Cretaceous Erlian Formation,Erlian Basin,Inner Mongolia,People's Republic of China

The Erlian Basin is one of the non-marine Cretaceous basins of north-east China that developed during the late Mesozoic continental extension in eastern Asia. This basin experienced two major tectonic events: (i) a syn-rift stage that was dominated by a fluvial–lacustrine depositional environment and (ii) a post-rift stage that was dominated by a fluvial environment. A new sedimentological study performed on Erlian Formation drill cores has led to the determination of an architectural model and to the subsequent characterisation of the stratigraphic evolution of this sedimentary unit during the late Cretaceous. The palynological occurrences that were identified in samples provided a possible stratigraphical age for the Erlian Formation.Sediments of the Erlian Formation occur at the top of the Cretaceous stratigraphic column of the Erlian Basin and were deposited during the post-rift stage. Facies architecture and the ideal succession of facies that were identified for this formation exhibit two different members, both dominated by a fluvial depositional environment: (i) the lower member, which is dominated by channels of a braided river system and (ii) the upper member, which is dominated by overbank deposits. The lower member expresses a tectonically induced uplift as indicated by channels clustering under negative accommodation, whereas a period of stratigraphic base-level rise that is associated with an increase of accommodation is identified in the upper member. Therefore the Erlian Formation highlights an alternation of short uplifts that were dominated by braided fluvial channel deposits with periods of stratigraphic base-level rise that were dominated by overbank deposits. This sedimentological architecture has significant metallogenic implications for the origin of confined permeable sandstone layers, which represent adequate host-rocks for roll front-type uranium deposits.The palynological assemblage Exesipollenites, Ulmipollenites/Ulmoideipites, Buttinia and Momipites that were recognised in two samples of the Erlian Formation has revealed a post-late Campanian age therefore more likely indicating a late Cretaceous age of deposition for the sediments of the Erlian Formation.     

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。     

珠江口盆地白云凹陷晚渐新统-早中新统沉积特征及演化规律

以珠江口盆地白云凹陷钻井、测井、地震和古生物资料为基础,结合前人研究成果,系统的分析了白云凹陷晚渐新统到早中新统沉积相发育特征及凹陷沉积充填演化过程。研究结果表明,珠海组下部发育大型陆架边缘三角洲沉积,地震反射特征表明该三角洲发育三期;钻遇水下分支河道、支流间湾、河口坝及远砂坝微相,沉积物以富砂为特征,发育冲刷-充填构造、递变层理及较粗的水平潜穴等多种构造;珠海组上部为浅海相,沉积物以海相砂泥岩互层为主,此时期陆架坡折带位于白云凹陷南坡;珠江组沉积时期,海平面升降旋回频繁,陆架坡折带迁至凹陷北坡。随着古珠江流域扩大,沉积物输入量增加,在珠江组下部发育了深水扇,沉积物以细-粗砂岩为主,夹少量粉砂岩及深海泥岩,发育颗粒流、液化流、浊流及碎屑流等四种主要的重力流,钻遇内扇水道,中扇废弃水道及水道间漫溢沉积,外扇深海泥沉积;珠江组上部为半深海相,沉积物以深海泥岩为主。      

黄骅盆地港西开发区新近系明化镇组沉积微相特征

综合利用油田开发区岩心和测井等资料,对黄骅盆地港西开发区一区l断块新近系明化镇组进行沉积微相研究。结果表明,明化镇组为中一高弯度曲流河沉积,沉积微相单元可以细分为主河道、支河道、河间溢岸沉积、废弃河道和泛滥平原等,不同的微相单元在测井曲线上具有较好的电性响应特征。在总结沉积微相发育模式的基础上,认为在高可容纳空间体系阶段,孤立的条带状河道砂体镶嵌在大面积分布的河间及泛滥平原细粒沉积背景当中,河道砂体被泥岩所分隔;而在低可容纳空间体系阶段,多层不同期次的河道砂体发生切割叠置,造成砂体厚度较大,连通性较好。垂向上,河道砂体的不同配置方式体现了A／S比值随时间的旋回性变化的控制作用。     

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。     

黔东北地区大塘坡组早期含锰沉积充填、岩相古地理与锰矿的关系

黔东北地区是中国南华纪"大塘坡式"锰矿重要富集区,而岩相古地理是沉积型锰矿最重要的控矿因素。笔者根据松桃—江口地区南华系各组岩性及碎屑锆石年龄特征对清水江组、两界河组、铁丝坳组及大塘坡组进行细致的地层划分,在建立了本区南华纪大塘坡早期沉积充填序列的同时,将本区沉积盆地划分为4个Ⅱ级盆地、12个Ⅲ级盆地以及11个次级(Ⅳ)聚锰盆地。在不同盆地内的大塘坡一段中识别出14种岩相类型,划分出2类沉积系、10类主要的岩相古地理单元,进而编绘了本区南华纪大塘坡早期岩相古地理图。提出在大陆边缘裂谷盆地的背景下,研究区南华纪大塘坡早期沉积环境应属大陆边缘障壁海岸体系,属于典型的"大塘坡式"锰矿,与障壁后侧迅速沉降的深水局限盆地密切相关。     

Mineralogy, geochemistry, and palynology of modern and late Tertiary mangrove deposits in the Barreiras Formation of Mosqueiro Island, northeastern Pará state, eastern Amazonia

A coastal environment has been interpreted from 110 cm thick mudstone deposits found at the base of a 10 m immature laterite profile, which forms the modern coastal cliff on Mosqueiro Island in northeastern Pará state, northern Brazil. The late Tertiary sediment deposits of the Barreiras Formation are studied by multi-element geochemistry and pollen analyses. The mineralogical and geochemical results show that the gray, organic-rich deposits are composed of kaolinite, quartz, and illite/muscovite, as well as pyrite and anatase. They are rich in SiO₂, Al₂O₃, and some FeO. The composition is homogenous, indicating that the detritus source area is formed of lateritic soils derived from acid rock composition. Their chemical composition, including trace elements, is somewhat comparable to continental shale, and the values are below the upper continental Earth crust composition. The pollen analytical data document that the mudstone deposits were formed by an ancient mangrove ecosystem. Mineralogical, geochemical, and pollen analytical data obtained from late Tertiary mangrove deposits are compared with modern mangrove deposits from the Bragança Peninsula of the northeastern coast of Pará state. Although the pollen composition of the deposits is very similar to the modern one, the geochemical and mineralogical composition is different. Smectite was only found in the modern deposit; illite/mica occurs in the ancient deposit, along with Mg, K, and Na. The pollen signature and detrital minerals (kaolinite, quartz and anatase) found in both mangrove deposits show that during the Miocene, a humid tropical climate condition prevailed, similar to modern conditions.     

华北中南部博山地区上古生界沉积相与沉积演化特征

随着中浅层油气勘探进入中高成熟阶段,华北地区上古生界已成为油气勘探和储量接替的重要领域,对上古生界沉积相类型及沉积演化过程进行深入研究对于油气勘探具有一定的指导意义。以沉积学理论为指导,以华北中南部淄博博山上古生界露头剖面为基础,通过详细踏勘实测,识别其发育的沉积相类型与沉积序列,明确其沉积演化过程。研究结果表明:淄博博山地区上古生界自下而上可分为本溪组、太原组、山西组、下石盒子组、上石盒子组和石千峰组,共识别出障壁海岸、潮流、碳酸盐台地、三角洲和曲流河5种沉积相及8种典型沉积序列;本溪组-太原组发育障壁海岸相和碳酸盐台地相,山西组发育三角洲相,下石盒子组-石千峰组发育河流相和潮流相;研究区上古生界经历了由障壁海岸-台地复合沉积体系过渡为三角洲相,最终转变为河流相的沉积演化过程。     

准噶尔盆地南缘古近纪—新近纪前陆盆地沉积格局与演变*

针对准噶尔盆地南缘古近系和新近系碎屑岩沉积体,运用野外露头宏观分析与岩心、薄片微观描述来 “定岩相和沉积相”;依据地震相的不同特点及相变的不同位置,刻画湖岸线演化,从而对沉积体“定边界”;根据重矿物组合特征及砂岩等厚图来“定主次物源”的方法,综合研究前陆盆地的沉积相特征。在此基础上,分析了准噶尔盆地南缘湖盆沉积格局与演变,认为准噶尔盆地南缘古近系紫泥泉子组沉积时期,湖平面较低,天山山前带发育4个规模较大的扇三角洲朵状体;至安集海河组沉积时期,湖平面上升,山前带扇三角洲发生退积,仅沉积3个规模变小的朵状体,霍尔果斯地区扇三角洲朵状体不发育。新近系沙湾组沉积时期,由于逆冲推覆构造作用,山前带地形高差大、坡度陡且气候干旱,随着湖平面的迅速下降,山前带发育更大规模进积型扇三角洲沉积。准噶尔盆地南缘古近系—新近系2个主要物源分别是中部东湾—吐谷鲁—玛纳斯背斜、西部西湖—独山子背斜;2个次要物源分别为东部呼图壁背斜和中西部霍尔果斯背斜,此4个物源流向是由南向北。北部卡因迪克地区则是来自前陆隆起区的重要物源。     

陆相盆地浅水背景河湖交互特征及其模式

通过对现代鄱阳湖盆中沉积体系发育与湖盆季节性湖岸线迁移变化耦合关系研究,结合对新近纪馆陶组时期渤海湾盆地渤东地区沉积岩性、沉积序列及沉积构造等解剖,提出陆相湖盆浅水背景河湖交互沉积模式.基于对浅水湖盆鄱阳湖随季节更替引起的湖平面变化分析,识别出洪-平-枯水线,划分河控主体区(A区)、河湖交互区(B区)和湖泊主体区(C区...     

Spatial sediment variability in a tropical tide dominated estuary: Sources and drivers

Surficial sediment composition and spatial variability reflect the dynamics and level of natural and anthropogenic impact in estuarine systems. The aim of this study is to evaluate some key environmental and sedimentary variables, as well as to evaluate the current environmental quality in the tide-dominated Caravelas estuarine system (Brazil). Sixty-five surficial sediment samples were studied for grain size as well as calcium carbonate, total organic carbon, total nitrogen, metals, semi-metals and rare earth elements and for organic matter δ¹³C. Based on the spatial distribution of these data and summarizing our findings, three sectors can be individualized in the Caravelas estuarine system: i. Barra Velha inlet; ii. the main channel of the Caravelas estuary, and iii. the channel interconnecting Caravelas and Nova Viçosa estuaries. In the inlet the sedimentary organic matter is provided essentially by marine sources, which corroborates the small continental input. Freshwater dissolved organic carbon and particulate organic carbon occur in the interconnecting channel, proving the occurrence of the residual transport towards the Caravelas estuary, with continental contribution towards Caravelas River. The geochemical fingerprint indicates that the Barreiras Group, composed by Neogene terrigenous deposits, located west of the study area, as an important source of terrigenous material to the entire Caravelas estuary system. The higher values of heavy rare earth elements (between 20 and 30 mg kg⁻¹) in the northern sector of the study area may be related to the high degree of chemical weathering in magmatic or metamorphic rocks, which occur to the north of the study area.     

柴北缘地区层序格架下的沉积特征

中国中西部含油气沉积盆地大多具有前陆盆地层序组合特征,可以识别出前陆层序和非前陆层序。柴达木盆地柴北缘层序地层格架主要包括非前陆层序的侏罗系和古近系以及前陆层序的新近系。通过井剖面层序分析结合有限的地震剖面,可以对柴达木北缘侏罗系划分7套III级层序。古近系—第四系划分11套III级层序。侏罗系属于非前陆期沉积,新近系属于前陆期沉积。通过柴北缘地区层序框架下沉积特征的解剖,表明柴北缘地区非前陆期遗迹化石以缺氧环境化石群为主,沉积相以河流-湖沼体系为特征。前陆期遗迹化石以陆相氧化河湖相环境化石群为主,湖退体系域(RST)冲积扇-河流三角洲-滨浅湖相沉积体系非常发育。柴达木盆地的沉积层序表现为受构造强烈活动和气候变化的影响,强烈活动期潮湿气候下层序表现为山前带发育进积式准层序组,凹陷区形成退积式准层序组。干旱气候配合下的层序表现为多物源更加明显,山前带沉积物供应更加迅速,且沉积中心迁移强烈。