Tricyclic terpane maturity parameters: response to heating by an igneous intrusion     

《Organic Geochemistry》1999,30(8):1011-1019

The effects of thermal maturation upon the abundance and composition of the tricyclic terpanes have been investigated within a single sedimentary horizon within the Dun Caan Shale Member (Isle of Skye, Scotland) intruded by a 0.9 m thick Tertiary dolerite dyke. Heating by the igneous body caused the concentrations of all 13β(H),14α(H) and 13α(H),14α(H) tricyclic terpanes to increase towards or within the effective ‘oil window’, recording generation from abundant non-hydrocarbon precursors, such as kerogen- and asphaltene-bound components. Progressive changes in tricyclic terpane composition accompany these concentration changes. An increase in the C₂₃ βα/αα maturity parameter towards the dyke resulted from the relatively greater rate of generation of the βα isomer, combined with the earlier decline in concentration (by degradation or isomerisation) of the αα component. The tricyclics/(tricyclics+hopanes) parameter shows a dramatic increase within the latter part of the oil window, due to the greater relative thermal stability of the tricyclic terpanes. The quantitative data demonstrate the importance of the processes of generation (from non-hydrocarbon fractions of the sedimentary organic matter) and thermal degradation in the operation of tricyclic terpane maturity parameters.  相似文献   

华北板块奥陶纪牙形石生物地层研究回顾及在西北缘区新进展     

景秀春  周洪瑞  王训练  杨志华  房强  王振涛  樊杰 《地学前缘》2020,27(6):199-212

牙形石在以碳酸盐岩为主的华北奥陶系划分对比中占有举足轻重的地位。针对华北奥陶纪牙形石的研究已持续近半个世纪,总体上可以分为两个阶段:第一阶段自20世纪70年代到21世纪初,第二阶段为最近10年(2010—2020)。第一阶段以建立牙形石生物地层序列为目标,主要为解决石油勘探过程中地层时代的确定和地层对比的需求;第二阶段的研究以修订化石带为主,目的是与国际地层研究接轨。近年来在华北板块西北缘的工作显示,该区奥陶纪牙形石在纵向上具有显著的生态变化,可分为达瑞威尔期中期、达瑞威尔期晚期—桑比期中期、桑比期晚期—凯迪期中期3个时段。第一时段以介于北美中大陆区和北大西洋区之间的热带台地边缘型牙形石为特征;第二时段以北大西洋型为主混有少量亚澳型牙形石为特征;第三时段以亚澳型和北美中大陆型牙形石混生为特征。在华北西北缘尽可能使用广布性标准牙形石属种进行化石带厘定,共识别牙形石带12个,自下而上分别是达瑞威尔期Histiodella cf. holodentata间隔带、Histiodella kristinae谱系带、Histiodella bellburnensis延限带、Dzikodus tablepointensis间隔带、Eoplacognathus suecicus间隔带、Pygodus serra间隔带和Pygodus anserinus(早期型)间隔亚带,桑比期Pygodus anserinus(晚期型)间隔亚带和Belodina compressa间隔带,凯迪期Belodina confluens间隔带、Yaoxianognathus neimengguensis间隔带和Yaoxianognathus yaoxianensis间隔带。由于部分化石带与国际同名带的对比还存在一些矛盾,尚需今后进一步解决。  相似文献   

冀中坳陷饶阳凹陷蠡县斜坡古近系沙河街组一段浅水三角洲和滩坝的沉积环境^*          下载免费PDF全文

叶蕾  朱筱敏  张锐锋  谢爽慧  高园  唐宏  齐雪竹  陈亚青 《古地理学报》2020,22(3):587-600

浅水三角洲和滩坝不仅是当今沉积学研究热点,也是油气勘探重要的沉积类型,沉积环境控制着浅水三角洲和滩坝沉积体系的发育及演化。基于岩心、钻井、测井数据及孢粉化石、微量元素等分析化验资料,对渤海湾盆地冀中坳陷饶阳凹陷蠡县斜坡古近系沙河街组一段(简称“沙一段”)的沉积体系类型及沉积环境进行了综合研究。研究表明: (1)沙一段主要发育浅水三角洲和滩坝沉积。其中,沙一下亚段尾砂岩沉积时,以浅水三角洲内前缘、外前缘沉积为主;沙一下亚段特殊岩性段沉积时,湖平面上升,浅水三角洲退积,以滨浅湖滩坝为主;沙一上亚段沉积时,湖平面下降,三角洲向湖盆中心持续推进,沉积主体转变为浅水三角洲。(2)浅水三角洲和滩坝的沉积演化受控于沉积环境。沙一下亚段尾砂岩沉积时,处于较为干旱的亚热带气候,沉积水体较浅,为微咸水—半咸水的氧化环境,有利于浅水三角洲的发育;沙一下亚段特殊岩性段沉积时,发生大规模湖侵,水体加深,物源供给少,气候相对湿润,且盐度增加,过渡为还原环境,有利于滨浅湖滩坝的形成;沙一上亚段沉积时,物源供给充足,整体处于相对湿润的温带、亚热带气候,湖盆收缩,水体变浅,盐度相对较低,处于氧化条件下的淡水环境,有利于浅水三角洲的沉积。  相似文献   

饶阳凹陷大王庄地区古近系东营组三段沉积微相研究     

张强  郭发军  谢俊  张淑娟  陈小琴  郝鹏  许敏 《地质与资源》2020,29(3):252-259

针对大王庄地区沉积相类型判定结论不一致的问题,以区域构造演化为基础,利用钻井数据、沉积构造标志、测井数据等地质资料,探讨了东营组三段（Ed₃）沉积时期周边潜山、洼槽对大王庄地区物源方向、沉积相类型的控制作用,建立了东三段沉积模式.研究结果表明,东三段沉积时期,沉降中心位于研究区东北部,主要接受西南深泽低凸起的物源沉积.东营组沉积期间,随着断陷的抬升,湖盆面积迅速缩小,地形逐渐平坦,沉积相不断延伸,大王庄地区东三段发育曲流河相.沉积相的精细研究为储层预测提供了依据.  相似文献   

二连盆地下白垩统沉积相及含油性   总被引：10，自引：1，他引：9       下载免费PDF全文

张文朝 《地质科学》1998,33(2):204-213

根据大量钻井剖面、地震剖面、岩芯观察、野外出露剖面和岩石分析资料,研究了二连盆地近30个凹陷的下白垩统沉积相,并以勘探程度较高的阿南、吉尔嘎朗图等7个凹陷为重点,恢复了早白垩世的岩相古地理环境,总结了下白垩统的沉积特征、主要沉积体系和油气分布规律,并指出今后的油气勘探方向。  相似文献   

The distribution and origin of dimethyldibenzothiophenes in sediment extracts from the Liaohe Basin,East China     

《Organic Geochemistry》2013

The distributions of dimethyldibenzothiophenes (DMDBTs), the relationship between DMDBTs and dimethylbiphenyls (DMBPs), and the applications of DMDBTs as maturity indicators in source rocks have been investigated in a set of 21 lacustrine shales from the Eocene Shahejie Formation (Well SG1) in the Western Depression, Liaohe Basin, China. All source rock samples are characterized by total organic carbon contents of 1.37–3.27% and Type II (with minor Type III) kerogen. They were deposited in suboxic and brackish lacustrine environments and have maturities ranging from immature to mid-mature. The 3,3′-DMBP isomer can potentially react to yield 4,6-DMDBT; 2,6-DMDBT and 2,8-DMDBT by incorporating sulfur into biphenyl, which may be supported by a strong positive correlation between the absolute concentration changes of 3,3′-DMBP and those of 4,6-DMDBT, 2,6-DMDBT plus 2,8-DMDBT. The relative abundance of DMDBT isomers may be explained by the sulfur radical mechanism and are also controlled by steric hindrance and thermodynamic stability. The 4,6-/(1,4- + 1,6)-DMDBT ratio shows no regular trend with increasing maturity at the low stage, and it should be used with caution as a maturity indicator for immature sediments. However, within the oil generation window, the relative concentration of 4,6-DMDBT progressively increases with increasing maturity, which can be explained by its higher thermodynamic stability relative to the 1,4-DMDBT isomer. The 4,6-/(1,4- + 1,6)-DMDBT ratio exhibits a linear increase with increasing thermal maturity of the sediments. Thus, this ratio can be applied as an effective maturity indicator for source rocks within oil generation window.  相似文献   

The development of sheath folds in viscously stratified materials in simple shear conditions: An analogue approach     

《Journal of Structural Geology》2013

Sheath folds are highly non-cylindrical folds occurring in a variety of geological settings, and have been studied using different approaches. With the present work, we provide a quantitative analysis of the generation and development of sheath folds in a viscously layered system in simple shear conditions. The sheath folds develop from an initial non-cylindrical deflection located on the highly viscous layer. The analogue experiments investigated the influence of (1) variations in the viscosity ratio between the high viscosity layer and the matrix (η_hvl/η_m), (2) variations in the ratio between the amplitude of the initial deflection and the thickness of the high viscosity layer (A_f/T_hvl), and (3) progressive simple shear (γ). The results show that increases in η_hvl/η_m will produce progressively less elongated sheath folds, while increases in A_f/T_hvl will result in more elongated sheath folds. We present regime diagrams with η_hvl/η_m and A_f/T_hvl for different shear strains illustrating under which conditions sheath folds form. In case the original deflection amplitude and layer thickness as well as γ can be retrieved for sheath folds in nature, then their geometry can be used to quantify the effective η_hvl/η_m.  相似文献   

川东北前陆盆地上三叠统沉积相及沉积演化   总被引：1，自引：0，他引：1       下载免费PDF全文

毛琼  郑荣才  邹光富  杨凯  王芳  张志勇 《沉积与特提斯地质》2012,32(1):1-11

在对川东北前陆盆地上三叠统须家河组露头剖面野外实测和钻井等资料综合研究的基础上,对该区上三叠统须家河组层序及沉积相类型、沉积特征进行了详细的研究。结果表明:研究区内主要发育冲积扇、辫状河、曲流河、扇三角洲、辫状河三角洲、曲流河三角洲、湖泊、海相三角洲等八种主要的沉积相类型。古地理演化经历了由海相环境—海陆过渡相环境—陆相环境的转变。反映了川东北前陆盆地晚三叠世须家河期盆-山耦合过程及其沉积响应。须一段(即小塘子期)发育时期,受印支期构造运动的影响,本区大部分隆升成陆,仅在研究区北西部广元、剑阁等地发育海相三角洲相沉积。须二段发育时期,米仓山-大巴山构造山系的逆冲推覆构造作用较为强烈,川东北前陆盆地坳陷幅度加大,沉积物供给充分,沿米仓山-大巴山前缘地带主要发育辫状河三角洲沉积,而盆地西南部主要发育浅湖沉积。在须三段发育时期,米仓山-大巴山构造山系构造活动逐渐减弱,处于低幅稳定隆升状态,碎屑物供给量减少,沿米仓山-大巴山前缘地带主要发育辫状河三角洲沉积;从盆地前缘地带向中心地带则主要发育浅湖沉积。须四-须六段发育时期,米仓山-大巴山开始进入强烈逆冲推覆和构造隆升阶段,川东北前陆盆地坳陷幅度急剧加大,碎屑物供给量骤然增多,从盆地前缘地带向中心地带主要发育冲积扇-扇三角洲-辫状河三角洲、曲流河、曲流河三角洲相到浅湖相沉积。  相似文献   

陆上地震数据多次波压制策略     

苑益军  张锐锋 《现代地质》2012,26(6):1237-1243

在陆上地震勘探中,多次波反射与其他干扰波一样,干扰了有效波反射信号并降低了资料的信噪比。根据陆上地震数据中多次波与一次波所表现的不同特点,提出利用动校正叠加技术和频率-波数(f-k)滤波方法相结合的策略以压制地震数据中的多次波。使用一次波速度的动校正叠加技术可以衰减地震数据中的一部分多次波能量;根据叠加剖面确定包含剩余多次波的CMP范围,将f-k滤波方法应用于这些CMP道集上进一步压制多次波。模型试算和实际数据处理结果表明,所提出的多次波压制策略,不仅能有效地衰减多次波能量,而且在处理过程中可以减少对有效波信号的伤害。  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987114000322     

Yusheng Wan  ;Xianzheng Zhao  ;Zejiu Wang  ;Dunyi Liu  ;Alfred KrOner  ;Chunyan Dong  ;Hangqian  ;Yuansheng Geng  ;Yuhai Zhang  ;Runlong Fan  ;HuiyiSun 《地学前缘(英文版)》2014,5(4):471-484

The Central Hebei Basin （CHB） is one of the largest sedimentary basins in the North China Craton, extending in a northeast-southwest direction with an area of 〉350 km2. We carried out SHRIMP zircon dating, Hf-in-zircon isotopic analysis and a whole-rock geochemical study on igneous and metasedi- mentary rocks recovered from drill holes that penetrated into the basement of the CHB, Two samples of gneissic granodiorite （XG1-1） and gneissic quartz diorite 048-1） have magmatic ages of 2500 and 2496 Ma, respectively. Their zircons also record metamorphic ages of 2.41-2.51 and ～2.5 Ga, respec- tively. Compared with the gneissic granodiorite, the gneissic quartz diorite has higher REE contents and lower Eu/Eu＊ and （La/Yb）n values. Two metasedimentary samples （MG1, H5） mainly contain ～2,5 Ga detrital zircons as well as late Paleoproterozoic metamorphic grains. The zircons of different origins have eHf （2.5 Ga） values and Hf crustal model ages ranging from 0 to 5 and 2.7 to 2,9 Ga, respectively, Therefore, ～2.5 Ga magmatic and Paleoproterozoic metasedimentary rocks and late Neoarchean to early Paleoproterozoic and late Paleoproterozoic tectono-thermal events have been identified in the basement beneath the CHB. Based on regional comparisons, we conclude that the early Precambrian basement beneath the CHB is part of the North China Craton.  相似文献