Upper Meotian facies of the Taman Trough

The facies structure and depositional environments of upper Meotian (Maeotin in European literature) sediments in the Taman Trough are considered. Eight facies of a shallow basin are defined and described in detail in the examined sections. It is established that depositional environments in the basin in the initial late Meotian were determined to a significant extent by the dominant influx of fresh (river) waters from the northeast. Diatomaceous sediments, which became later widespread, reflect cyclic ingressions of saline waters. Their enhanced inflow in the terminal late Meotian is evident from the taxonomic composition of diatom and molluscan assemblages.     

Middle Sarmatian facies of the Taman Trough

The sequential accumulation of middle Sarmatian sediments in the Taman Trough in the terrigenous and carbonate settings is considered. Six facies of the shallow-water basin are identified. The first half of the middle Sarmatian was marked by the accumulation of dominant clayey sediments. The formation of small serpulid-microbial bioherms took place under relatively deep conditions (upper part of the lower sublittoral zone). The terminal middle Sarmatian was dominated by the deposition of carbonates with a wide development of bacterial-algal mats. Their formation in the upper sublittoral setting below the base level of ordinary waves was intermittently disturbed by the enhanced influx of terrigenous material and accumulation of clays, as well as by the storm-induced roiling and bioturbation.     

Clay minerals in the middle-upper Miocene sediments of the Taman trough: Composition and paleogeographic significance

The pioneer compositional analysis carried out for clayey sediments from most regional Miocene stages of the Taman trough made it possible to define the main types of clays and trace their variability through the section. It is established that the composition of these clays is largely controlled by the sedimentary rather than postsedimentary lithogenetic factors. The maximal hydromica (hereafter, illite) concentrations (up to 73%) are recorded in sediments deposited during orogenesis activation and major regressions (terminal Tarkhanian, Sarmatian, and early Pontian). The dominant role and elevated concentration of the smectite component are characteristic of sediments corresponding to transgressive phases of the basin development. The shallow-water sediments, which show a notable facies heterogeneity, differ from their deepwater counterparts by a higher diversity in the clay composition. These regularities in the distribution of clay minerals may be used for the lithostratigraphic subdivision of the sequences with a lower content of the fossil mollusc assemblages.     

黔中-黔东南地区下志留统沉积相

下志留统由下向上分为龙马溪阶、大中坝阶和紫阳阶。黔北地区3个阶有连续的沉积物,而黔中-黔东南地区缺失早志留世龙马溪期和大中坝期早期的沉积。海平面的下降导致黔中隆起上的中下奥陶统成为暴露喀斯特地貌。以余庆-黄平地区为界分成了南、北2个区。南区只有紫阳阶的翁项组(或高寨田组)由南向北超覆在中下奥陶统岩溶暴露面上,在凯里至都匀一带为海湾-澙湖相的钙质砂泥岩沉积,向西至贵阳一带为开阔性的滨浅海沉积。早志留世的海侵改造了下伏岩溶喀斯特和古风化壳,沉积了波浪改造型的砾屑灰岩和海侵充填型的含灰岩砾块碎屑岩,两者均非"底砾岩"。     

西藏措勤盆地下二叠统昂杰组沉积相分析

沉积相研究是进行含油气盆地勘探、评价的一项重要的基础工作。笔者根据在西藏尼玛县军仓乡拉加当实测剖面中所获得的资料,分析了下二叠统昂杰组的岩性特性、沉积相类型、剖面的垂向沉积演化和区域沉积特征。该组主要为一套砂岩-泥岩的暗色碎屑岩系,属冈瓦纳石炭纪一二叠纪冰川末期的边缘海沉积。其沉积类型既有冈瓦纳大陆稳定沉积的特点,又有滨岸条件下的低能沉积特征,主要为一套潮坪沉积组合,其沉积环境与短周期小规模近岸冰川活动有关。     

Middle-Upper Miocene stratigraphy of the Taman Peninsula, Eastern Paratethys

The stratigraphy of the Taman Peninsula is defined using the sections at Zelensky Hill ?? Panagia, Popov Kamen, Taman and Zheleznyi Rog. The stratigraphy is constructed from distribution of mollusks, foraminifers, nannofossils, diatoms, and organic-walled phytoplankton, as well as incorporating paleomagnetic data. The occurrence of oceanic diatom species in the Middle-Upper Sarmatian, Maeotian and Lower Pontian makes a direct correlation possible between the sections studied, the Mediterranean basin and oceanic zonation. The new data on planktonic and benthic biotic groups suggests a pulsating connection of the Eastern Paratethys with the open marine basins, especially during transitional intervals within constant environments. Comprehensive studies of the Chokrakian-Kimmerian microbiota provide evidence for several levels of marine microbiotic associations that are related to short-term marine invasions. The biotic and paleomagnetic data of the Taman Peninsula sections give a more comprehensive, but sometimes a controversial picture on the Eastern Paratethys history and the nature of its relationship with the adjacent marine basins.     

准噶尔盆地西北缘检188井区下侏罗统八道湾组沉积特征及主控因素分析

通过对准噶尔盆地西北缘野外露头剖面和检188井区160多口井的岩石学特征、颜色、结构、沉积构造和古生物沉积相标志的研究,结合测井曲线响应特征,认为该区下侏罗统八道湾组属于湿润型辫状河沉积,发育河道和洪泛平原两个亚相。河道亚相又分为主水道、支水道和心滩3个微相,洪泛平原分为河漫滩、河漫沼泽和溢岸3个微相。测井曲线主要有箱形、钟形、漏斗形、指形和微齿形5种类型。在微相分析基础上编制了八道湾组12个小层的沉积微相平面图,建立了沉积相模式,指出河道呈东南向展布,认为由前陆湖盆边界区的造山运动导致的沉积区基准面变化和潮湿温暖的气候是影响研究区湿润型辫状河形成的主要控制因素。     

Stegosaur tracks and the persistence of facies — the Lower Cretaceous of Western Australia

Sometimes between January and June 1996, the only known stegosaur tracks were stolen from Broome in north-western Australia (Fig. 1). Vandalism or loss of any type material is always to be lamented, yet there is good cause to suspect that the trackmaker at Broome was not a stegosaur. The reasons why this should be so relate to some of the factors involved in the formation of dinosaur trace fossils and the difficulties encountered in their interpretation. The stratigraphy at Broome is notable for preserving evidence of potential Wealden-type deposition in Australia.     

滇西兰坪盆地五茂林剖面下白垩统景星组沉积相

实测了云南西部兰坪盆地东部下白垩统下部景星组的五茂林剖面,建立了曲流河、三角洲和湖泊3种沉积序列,其中三角洲序列在云南下白垩统中属首次建立。分析了粗碎屑岩的组成,将该剖面上出露的砾岩分成4类。早白垩世时兰坪盆地属丹那沙林-高黎贡弧的弧后盆地,景星组自下而上为曲流河沉积、三角洲沉积和湖泊沉积,且随湖侵发生,湖泊向西扩大。     

北疆沙尔布尔提山地区早泥盆-早石炭世沉积相、物源演变及其意义

准噶尔西北部沙尔布尔提山地区下泥盆统到下石炭统的沉积可划分为滨海相和海岸平原相。其中下泥盆统和布克赛尔组底部的乌图布拉克亚组为滨海碎屑岩相,曼格尔亚组为滨海碎屑岩和碳酸盐岩相,芒克鲁亚组为滨海碳酸盐岩相。中泥盆统呼吉尔斯特组为海岸平原相。上泥盆统洪古勒楞组底部为海岸平原相,向中部过渡为滨海碳酸盐岩相,顶部为滨海碎屑岩相。下石炭统黑山头组为滨海碎屑岩相。下泥盆统和下石炭统的古流向总体从北向南,显示研究区以北地区为物源区,即成吉斯-塔尔巴哈台褶皱带。结合沉积相的研究成果,本区可能属成吉斯-塔尔巴哈台褶皱带以南的晚古生代陆缘区。物源演变趋势分析揭示早泥盆世成吉斯-塔尔巴哈台带中的早古生代岛弧发生隆起,为乌图布拉克亚组提供成熟度很低的碎屑物质。随着岛弧被剥蚀殆尽,中、晚泥盆世呼吉尔斯特组和洪古勒楞组沉积时转而接受岩屑型再旋回造山带的物源供应,而早石炭世的物源则为过渡型再旋回造山带区。这种物源变化反映了成吉斯-塔尔巴哈台褶皱带的建造特征和隆起过程。     

藏南古错地区上侏罗统上部和下白垩统沉积相?

基于野外剖面和室内沉积学研究,对古错地区侏罗纪末期-早白垩世地层进行详细描述和修订,识别出6种主要岩相类型：红褐色（风化色）石英砾岩、灰色－黄绿色岩屑砾岩、灰白色石英砂岩、灰色－黄绿色岩屑砂岩、灰色－黄绿色长石岩屑砂岩、灰色、深灰色、黑色页岩。发现粒序层理、水平层理、平行层理、板状交错层理、丘状交错层理等层理构造、波痕和槽模层面构造、重荷模和砂岩岩墙变形构造以及侵蚀面构造、叠瓦状构造、硬底、结核等沉积构造和生物遗迹。识别出三角洲（包括三角洲前缘亚相和前三角洲亚相）和陆棚（包括受风暴影响的陆棚相亚相和深水陆棚相亚相）两类沉积相,其中三角洲前缘亚相进一步划分为水下分流河道、分流河口砂坝和远砂坝等微相。建立了侏罗纪末期-早白垩世沉积相序及其演化,并在此基础上分析了沉积环境变化。     

苏里格地区中二叠统下石盒子组盒8段沉积相研究

苏里格气田是我国大型砂岩性圈闭气藏,主力产气层为下石盒子组盒8段,本文根据岩心化验分析资料,测井资料,通过对前人研究成果的总结,认为苏里格地区盒8段为辫状河三角洲沉积体系。在深入细致的微相分析基础上,编制了盒8沉积时期的沉积相平面图。根据沉积相的时空展布规律,建立了本区盒8段沉积相模式。     

松辽盆地营城组火山岩相量化表征与应用

盆地火山岩及其储层的地震解释需要量化的岩相模型提供地质约束。三维揭露的盆缘剖面是实现岩相量化表征的最佳区。在松辽盆地东南隆起营城组建组剖面区开展了爆发相、喷溢相和侵出相的三维量化研究。爆发相出现在火山旋回早期,延伸千米量级、厚度百米量级,外形呈楔形尖灭状,坡度上陡下缓、呈平均15°左右的上凹形轮廓;始于热基浪亚相、向上为热基浪与空落亚相互层,终于热碎屑流亚相。喷溢相多出现在火山旋回中后期,覆于爆发相之上,延伸千米量级、厚度百米量级,外形呈凸透镜向外尖灭状,坡度上缓下陡、呈平均20°左右的上凸形轮廓;自下而上依次为下部、中部和上部亚相。侵出相出现在火山旋回后期,可见对其它相带呈切割-披覆关系的内、中、外三个亚相,侧向延伸和垂向厚度多为百米量级、通常最大不超过1km,呈顶缓缘陡的蘑菇状。用火山岩相模型约束井旁地震解释、建立岩相-地震相响应关系,可为无井区的火山岩地震识别提供模板。火山机构的后期改造只改变相序的完整性、不改变原始喷发相带间的相邻与相依性,不影响用岩相模式预测相变关系。非同源喷出物之间的叠置会干扰盆地火山岩相的解译,且使岩相模型的约束作用失效。     

Taxonomy, facies relationships and palaeobiology of bakevelliid bivalves from the Lower Cretaceous of west-central Argentina

Cretaceous bakevelliids in Argentina are restricted to the Lower Cretaceous. They are recorded in shallow marine deposits in two Mesozoic basins located in the Andes foothills in Patagonia. In the Austral Basin (44°–55°S) there is only one genus, Gervillella, represented by a single specimen from the Barremian. In the Neuquén Basin (30°–40°S) two genera, Gervillaria and Gervillella, occur, ranging from the Berriasian to the Lower Barremian. In the Pilmatué Member of the Agrio Formation two species are identified: Gervillaria alatior (Imlay) and Gervillella aviculoides (J. Sowerby). The former is also recorded in Mexico while the latter is more widespread, occurring in Europe, Asia, and Africa. In the Bajada del Agrio section they come from eight tabular shell beds located near and on top of shallowing-upwards cycles. They were abundant only in four of these levels. These shell beds are interpreted as having been deposited in the mid-ramp (middle of cycles), and upper mid-ramp (top of cycles). A functional analysis of shells revealed two life habits: epibyssate and endobyssate.     

川北地区下寒武统龙王庙组沉积相 及与储层的关系

以四川盆地北部下寒武统龙王庙组为研究对象,利用野外露头、测井及岩心等资料,探讨了川北地区下寒武统龙王庙组的沉积相类型及特征,并分析了其对储层的影响。研究认为:川北地区在早寒武世龙王庙期的沉积环境为碳酸盐台地,发育潮坪、局限台地和开阔台地等3种相带,这些相带又进一步细分为混积潮坪、台内点滩、潟湖和滩间海等4种亚相。其中,混积潮坪亚相主要发育砂质白云岩坪、白云岩坪等,部分地区可见潮道;台内点滩亚相以砂屑白云岩最为常见,沉积厚度不大;潟湖亚相以白云质潟湖沉积和白云质灰质潟湖沉积为主,分布面积大;滩间海亚相沉积物以深灰色块状石灰岩为主,局部夹白云质豹斑灰岩。纵向上,大部分地区龙王庙组沉积由2次海退旋回构成,潟湖主要发育在单个沉积旋回的中下部;台内点滩主要发育在沉积旋回的中、上部,单个滩体厚度较薄;混积潮坪发育在旋回顶部,即旋回末期。平面上,由于受古陆影响,研究区自西向东具有物源供应减少、沉积水体逐渐变深,以及沉积相从潮坪—局限台地—开阔台地过渡的特征,台内点滩主要围绕局限潟湖分布。结合不同沉积相带储层物性的分析,认为台内点滩的颗粒白云岩储集性能最好,晶粒白云岩次之,膏盐岩最差。龙王庙组储层发育的最有利沉积环境为台内点滩。     

四川盆地下三叠统嘉陵江组主要成盐期岩相古地理特征

四川盆地下三叠统嘉陵江组是我国钾盐矿产勘查的重点区域和层位,对其的岩相古地理研究是钾盐研究的一项重要的基础地质工作。本文结合四川盆地古地理背景和古气候条件,通过野外剖面、岩心观察、薄片鉴定等方法,对研究区下三叠统嘉陵江组的沉积相进行了分析研究,共识别出潟湖、潟湖边缘坪和台内滩相三种沉积相类型,并进一步划分出多种微相。在此基础上,通过区域地层对比以及岩相古地理编图,重建了四川盆地下三叠统嘉陵江组岩相古地理演化。结合前人研究认为：四川盆地嘉陵江组整体上属于障壁碳酸盐岩台地沉积环境,自西向东从碳酸盐岩局限海相演化为蒸发台地相。盆地周边水下隆起的障壁作用和干旱炎热气候条件共同影响了嘉陵江组台地咸化的演化过程,海平面升降变化是控制沉积相发育和空间分布的重要因素。最后,基于本研究的资料,编制了嘉陵江组各成盐期的岩相古地理图。     

准噶尔盆地西北缘乌尔禾鼻隆中下三叠统沉积相特征

通过岩芯观察、薄片鉴定、测井和录井资料分析,认为准噶尔盆地西北缘乌尔禾鼻隆地区三叠系百口泉组和克拉玛依组主要发育砂砾岩、砾岩、砂质砾岩及少量砂岩、泥岩;该区的储层以低孔低渗为主,在克拉玛依组可见到少量中孔中渗储层;通过单井沉积相、剖面沉积相研究,结合研究区的构造背景和沉积环境,认为研究区物源以其西部黄羊泉以西地区为主,北部哈拉阿拉特山为辅;百口泉组发育冲积扇沉积,克拉玛依组发育扇三角洲沉积,沉积环境控制了研究区优质储层的分布。     

川东及其周缘地区下寒武统龙王庙组沉积相

通过野外露头、钻测井、三维地震及区域地质调查等资料的综合研究发现,川东及其周缘地区下寒武统龙王庙组岩石类型以碳酸盐岩(粉晶白云岩、颗粒白云岩、泥晶灰岩和颗粒灰岩)为主,局部发育大套蒸发岩(膏岩和云质膏岩)及碳酸盐岩与碎屑岩的混合沉积;识别出局限台地相、开阔台地相、蒸发台地相和混积台地相4种沉积相类型,以局限台地相最为发育;川东及其周缘地区龙王庙组各沉积相带呈北东—南西向展布,混积台地相分布于研究区西北部,蒸发台地相集中发育在研究区西部华蓥山断裂东侧,局限台地相分布于混积台地相以东到盆地东边界以西的地区,开阔台地相分布于局限台地相以东到广海的部分地区。