共查询到20条相似文献，搜索用时 24 毫秒
1.
根据岩石薄片、Ｘ衍射和扫描电镜分析资料,本文研究了巴州坳陷下白垩统—中侏罗统粘土矿物特征,发现粘土矿物分为伊利石、伊／蒙混层和绿泥石三种类型。粘土矿物的类型和含量随深度而变化,形成了伊／蒙混层带、混层迅速转化带和伊利石带。粘土矿物的转化和自生粘土矿物的形成是沉积地层非常重要的成岩变化。 相似文献
2.
The Lower Cretaceous series, in the Western Saharan Atlas, shows important detritic deposits, particularly continental to nearshore red sandstones. Lithologically, it is an alternation of red clay and sandstone intercalated with some carbonate levels at the lower part of the series. These series can be subdivided into three lithostratigraphic units corresponding to Valanginian-Hauterivian, Barremian, and Aptian-Lower Albian. The lithostratigraphic analysis used to reconstitute the important subsidence in the Lower Cretaceous period, particularly in the Lower Albian. The Lower Cretaceous series could be considered as a geodynamic model characterized by individualization of independent depocenter filled with different detritic material and separated by Jurassic structures. This new situation appeared in the beginning of Lower Cretaceous (Valanginian-Hauterivian), following the Neocimmeriean tectonic phase, and it is increasing in the Early Albian, where differences of thicknesses are more important and allow the distinction of the depocenter. The biostratigraphic analysis of the clay samples yielded some foraminifera and palynomorphs. Benthic and planktonic foraminifera confirmed the Hauterivian age of the basal formation, also, two dominant forms of palynomorphs were recognized; according to the large stratigraphic distribution of the identified forms, it can be attributed to the Lower Cretaceous. 相似文献
3.
通过岩心观察、岩心物性统计和薄片鉴定等方法,对谭庄凹陷下白垩统碎屑岩储层类型及次生孔隙成因进行了研究。结果表明：谭庄凹陷下白垩统埋藏经历了早、中成岩阶段,目前处于中成岩A阶段。下白垩统砂岩储层类型主要有原生和次生孔隙,经历了由原生到次生的演化过程;不同井区成岩阶段不同,原生到次生孔隙的演化程度也存在差异。铸体薄片、扫描电镜的研究结果表明：谭庄凹陷下白垩统砂岩储层存在3个次生孔隙带,并且每口井的次生孔隙发育程度存在差别。次生孔隙的形成与长石、岩屑、石英的溶蚀,粘土矿物的脱水以及油气的充注密切相关;不同探井、不同井段砂岩次生孔隙的形成原因具有差异,长石、岩屑的溶蚀占主导地位,石英和粒间粘土杂基的溶蚀作用次之。 相似文献
4.
5.
The sedimentary background and sedimentary environment of the Lower Cretaceous of Lingshan Island, Shandong, remain unclear. There is considerable controversy as to whether the sedimentary environment was marine or continental. In this study, analyses were conducted with respect to indicators of paleosalinity, the chemical composition of clay, paleobiota, the characteristics of strata exhibiting salinization in eastern China during the Early Cretaceous, and the relationship between paleosalinity and paleoclimate. The results indicate that the sedimentary environment of the Lower Cretaceous Laiyang Group of Lingshan Island was that of a salified lake rather than a marine environment. This study not only provides a reference for determining the sedimentary environment of the Lower Cretaceous Laiyang Group of Lingshan Island but also offers a new perspective for the study of Cretaceous strata with salinization characteristics in eastern China. 相似文献
6.
《International Geology Review》2012,54(7):1305-1309
A study of clay variations ranging from Devonian to Lower Cretaceous. The type of clay minerals is believed to be directly related to the composition of the source rock and to the weathering processes of these rocks. --L.M. LeRoy. 相似文献
7.
The analysis of Upper Jurassic and Lower Cretaceous marine sections developed in surrounding structures of the Laptev Sea revealed that all of them are composed of terrigenous rocks, which enclose abundant concretions cemented by calcareous material. The Upper Jurassic portion of the section is the most variable in thickness and stratigraphic range of sediments usually including hiatuses. Its Lower Cretaceous part represented by the Boreal Berriasian (=Ryazanian) and lower Valanginian stages is most complete. The Upper Jurassic and Lower Cretaceous sections are usually composed of fine-grained rocks (clays and mudstones) in the west and coarser cemented varieties (siltstones and sandstones) with rare mudstone intercalations in the east. Practically all the investigated Upper Jurassic and Lower Cretaceous sections include readily recognizable age and facies analogs of the Bazhenovo Formation and Achimov sandstones, which are petroliferous in West Siberia. There are grounds to assume the occurrence of these formations also on the Laptev Sea shelf, which is confirmed by seismic records. Conditions favorable for the formation of potential hydrocarbon reservoirs could exist in the western part of the paleobasin along the Nordvik Peninsula coast and northeastern Tamyr Peninsula margin. Paleotectonic reconstructions presented in this work are well consistent with stratigraphic conclusions. 相似文献
8.
辽东苏子河盆地是早白垩世形成的小型断陷盆地,盆地内发育了相对连续的陆相沉积,是研究白垩纪陆地环境及气候演化的理想地区。早白垩世晚期沉积的聂尔库组地层出露连续,沉积现象典型。通过分析聂尔库组沉积岩类型、沉积构造、古生物化石及垂向沉积序列,可识别出扇三角洲相和湖泊相,其中扇三角洲相包括扇三角洲平原亚相、扇三角洲前缘亚相和前扇三角洲亚相,湖泊相主要为滨浅湖泥砂沉积。研究表明,聂尔库组形成于断陷盆地边缘陡坡带,属于间歇性洪水控制的扇三角洲—湖泊沉积体系,经历了扇三角洲—湖泊—扇三角洲的沉积环境变化,代表了断陷湖盆由深陷扩张期—抬升收缩早期的沉积充填过程。根据沉积岩与沉积相特征,结合古生物、特殊沉积、黏土矿物及地球化学资料,认为早白垩世晚期辽东地区总体与当时全球"温室气候"的大背景相一致,处于高温干旱/潮湿的气候条件,但这种高温气候具有不均一性,存在气候波动。 相似文献
9.
Investigation of the Triassic–Lower Cretaceous rocks of the Dal'negorsk key section (southern Sikhote Alin) revealed the following successive associations of authigenic clay minerals: (1) sericite–chlorite (Lower Triassic); (2) mica–chlorite (Anisian–Norian); (3) chlorite–mica (Rhaetian–Lower Jurassic); and (4) smectite–chlorite–mica (Upper Jurassic–Lower Cretaceous). These four associations reflect the primary composition of terrigenous admixture in the siliceous sediments and, hence, serve as important indicators of paleosedimentation conditions. The first association represents a product of the erosion of metamorphic rock complexes. The second one reflects the onset of volcanic activity within the sedimentation basin coinciding in time with a vigorous bloom of siliceous plankton (radiolarians) and short-term appearance of specific (anoxic) carbonaceous sediments in the sequence. The third association characterizes the epoch of minimal supply of the basin with volcanic and terrigenous clastic materials and the dominant accumulation of almost pure planktonogenic sediments. The fourth association marks the change of marginal-marine conditions for pelagic ones and is expressed in a significant input of pyroclastic and clastic materials and the formation of distal flysch deposits. 相似文献
10.
对酒东盆地红山地区下白垩统含铀目的层中黏土矿物进行扫描电镜（SEM）、X射线衍射（XRD）、X射线能谱（EDX）等的系统研究,结果表明：含铀目的层碎屑岩的源岩主要是碱交代的酸性岩浆岩,其黏土矿物类型主要为高岭石,其次为绿泥石。高岭石既有陆源高岭石,也有自生（蚀变）高岭石;高岭石化带（浅色带）可以作为该区铀矿找矿的主要标志层,其厚度和蚀变强度等可以作为判断该区铀矿富集程度的依据之一。绿泥石主要为自生绿泥石,与高岭石形成于不同时期,可能是由高岭石转化而成。黏土矿物研究显示,该区自白垩纪以来经历了由温暖潮湿气候逐渐向干旱气候转变的过程。 相似文献
11.
Four outcrops of Lower Cretaceous (Barremian) karst bauxites located in Teruel (NE Spain) were analysed to determine their mineral associations and genesis related to climatic palaeoweathering events and late superimposed kaolinization processes. The materials comprise metric‐sized pisolitic blocks embedded in a clay‐rich red groundmass. Fourteen samples were examined by X‐ray diffraction, optical microscopy, scanning and transmission electron microscopy and the major elements were analysed by inductively‐coupled plasma mass spectroscopy (ICPMS). The samples are composed of kaolinite, gibbsite, goethite, and hematite as the main phases, with diaspore, boehmite, anatase, and rutile as accessory minerals. The results show a complex sequence of mineralogical and geochemical processes that transformed the parent rock into the current bauxite materials. The clay‐rich groundmass constitutes the lateritic parent material of the pisolitic bauxites. In the parent material authigenic kaolinite (e.g. vermicular kaolinite and kaolinite between cleavage sheets of pre‐existing mica) has been observed; Fe oxides formed subsequent to kaolinite. In the pisolitic bauxites, mineralogical and textural evidence indicates that bauxitization took place at the expense of previous kaolinite, with gibbsite post‐dating the other Al hydroxides. The pisolitic bauxites also show a more homogeneous chemical composition and a relative Ti, Al and Zr enrichment. The data are consistent with an intense palaeoweathering event during the Lower Cretaceous (Barremian) under tropical climatic conditions (warm and humid). Several stages probably took place during the bauxitization process, suggesting variations in water saturation conditions. Subsequent karst reactivation stages and related collapses were responsible for the present lithostructure of the deposits and allowed late kaolinization not related to climate to take place. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
12.
13.
宜昌斜坡残留的白垩系盆地是认识中扬子地块白垩纪构造演化的一个窗口.基于对白垩系露头的构造-沉积特征的观察,并结合二维地震剖面的构造-地层解释,厘定了宜昌斜坡白垩系盆地的构造属性和沉积充填特征,构建了白垩系陆内挤压盆地的挤压断-坳结构.宜昌斜坡白垩系盆地是由天阳坪逆冲断裂带控制的陆内挤压盆地.下白垩统盆地为同造山期的挤压断陷,充填有扇三角洲-湖泊沉积体系;上白垩统盆地为后造山期的挤压坳陷,充填了冲积扇-辫状河-风成-浅水含膏湖泊沉积体系.宜昌斜坡和湘鄂西弧形带的上白垩统盆地属于陆内挤压盆地的挤压坳陷,揭示中扬子地块由挤压向伸展构造体制转换的起始时间是新生代. 相似文献
14.
针对天津滨海地区围海造陆工程所形成的上软、下硬双层软黏土地基,利用室内载荷试验和数值模拟开展了双层软黏土地基的承载特性及破坏模式研究。研究表明：由于下层沉积土的补强效应,双层软黏土地基的P-S曲线会出现明显的凹凸转折点,其出现的位置与宽厚比密切相关,宽厚比越小,转折点出现的时间越靠后,下层沉积土的补强效果越不明显。数值结果表明：双层软黏土地基破坏模式随着上覆土厚度的变化相差不大,均为整体剪切破坏。随着载荷板宽度的增加,双层软黏土地基以冲剪破坏模式过渡为局部剪切破坏,当载荷板宽度大于3.0 m时,表现为整体剪切破坏。 相似文献
15.
A detailed geochemical study has been made on clay minerals and organic matter from two stratigraphic sequences (Sully-Lepine Series and Buckinghorse Formation) in Lower Cretaceous shales from northeastern British Columbia. The characteristics of the discrete illites, mineralogy and chemistry of the mixed layer clays, organic extract yields and kerogen composition indicate that little diagenesis has occurred in the Sully-Lepine Series whereas extensive diagenesis verging on the anchizone of metamorphism has occurred in the Buckinghorse Formation.On the basis of this study and the results of other workers, a preliminary classification of diagenesis is proposed. Diagenesis is divided into three stages: eodiagenesis (early), mesodiagenesis (middle) and telodiagenesis (late). The mesodiagenesis stage is divided into two sub-stages. Eodiagenesis corresponds to the zone in which pore water is lost from the shales, little hydrocarbon generation occurs and coals are of lignitous or sub-bituminous types. Mesodiagenesis corresponds to the main phase of oil genesis and coals are of the high volatile to low volatile bituminous type. The first stage of clay dehydration occurs during early mesodiagenesis and the second stage of clay dehydration occurs in late mesodiagenesis. During telodiagenesis, extensive cracking of the organic matter occurs; dry gas is the main hydrocarbon product and coals fall in the semi-anthracite range.The preliminary classification has been applied to the Lower Cretaceous shales used in this study. The Sully-Lepine Series falls in the eodiagenesis and early mesodiagenesis zones whereas in the Buckinghorse Formation the diagenetic zones range from early mesodiagenesis to telodiagenesis. 相似文献
16.
The United Arab Emirates(UAE) is the 8 th largest oil producing country and is rich in oil and gas resources. By the end of 2015, 68 oil and 23 gas fields had been discovered. The initial proved and probable(2 P) oil, gas and condensate reserves amount to 81,135.9 MMb(million barrels), 192.09 Tcf(trillion cubic feet),and 6496.58 MMb respectively, which are mostly reservoired in the Jurassic and Cretaceous carbonates. With the latest field data, this study attempts to document the salient features of petroleum systems in UAE. Based on depositional facies of source rock intervals, pods of source rocks were delineated. On the basis of an oiland gas-source correlation, five known petroleum systems were identified and they are Lower Silurian-Upper Permian Khuff gas, northeast foreland Upper Jurassic-Lower Cretaceous gas, Upper Jurassic-Jurassic petroleum, Upper Jurassic/Lower Cretaceous-Lower Cretaceous composite petroleum, and Middle Cretaceous-Middle to Upper Cretaceous/Cenozoic petroleum systems. Of them, the Upper Jurassic/Lower Cretaceous-Lower Cretaceous composite petroleum system contains 73.2% of the total 2 P reserves and thus it is the focus of this study. The Upper Jurassic and Lower Cretaceous source rocks consist of argillaceous limestone, mudstone and shale, which were deposited as intrashelf basin facies. The distribution of oil and gas in this system is controlled by the source kitchens and the regional evaporite seal. 相似文献
17.
Palynological Analysis of Amber-Bearing Clay from the Lower Cretaceous of Central Lebanon 总被引：1，自引：0，他引：1
An amber-bearing lignitic layer of sandy clay from the Lower Cretaceous of Central Lebanon (Mderej-Hammana)yielded a well-preserved,moderately variegated palynoflora,which origin is mixed between land plants and marine microflora.Its detailed analysis led to fulfill its inventory,to propose a paleoenvironmental reconstruction,and to draw the paleoclimate which prevailed over the region:an estuarian area under a rather humid,temperate climate;a variety of ferns grew near the shore-side and in the inward l... 相似文献
18.
位于阿拉善台隆西北部的某盆地,是一呈EW向延伸的封闭盆地,盆地内冲积扇体系发育,主要沉积下白垩统新民堡群,局部有中下侏罗统地层。铀矿主要产于下白垩统新民堡群中岩组,扇前洼地亚相内的灰绿色细粒砂岩及泥质粉砂岩中。根据地质、水文地球化学环境等特征,结合成矿地质条件分析,认为盆地内铀成矿条件不利于形成具工业意义的铀矿,在有利层位及相带中可形成小规模铀矿。 相似文献
19.
20.
库车前陆盆地上侏罗统-下白垩统砾岩特征与构造演化关系 总被引：1，自引：1，他引：0
库车前陆盆地充填有上侏罗统喀拉扎组砾岩、下白垩统底部亚格列木组砾岩和下白垩统上部巴什基奇克组砾岩,通过对这三套砾岩区域分布特征、岩石学特征、砾态特征、厚度变化特征的详细描述与此三套砾岩沉积古环境的差异对比研究,认为库车前陆盆地中部库车河地区及西部卡普沙良河地区这三套砾岩成份复杂多样,具低成份与结构成熟度;所代表的气候演化特征由早到晚依次为:干旱、半干旱→温暖、湿润→干旱、炎热气候;所反映的沉积相为冲积扇、浊积扇和季节性辫状河沉积。砾岩与构造关系的结果分析表明,喀拉扎组砾岩是晚侏罗世构造活动的标志,亚格列木组砾岩为早白垩世初逆冲推覆活动的开始,巴什基奇克组砾岩则是早白垩世末构造宁静期的沉积响应产物。 相似文献