Biostratigraphic and aminostratigraphic constraints on the age of the Middle Pleistocene glacial succession in north Norfolk,UK

Considerable debate surrounds the age of the Middle Pleistocene glacial succession in East Anglia following some recent stratigraphical reinterpretations. Resolution of the stratigraphy here is important since it not only concerns the glacial history of the region but also has a bearing on our understanding of the earliest human occupation of north‐western Europe. The orthodox consensus that all the tills were emplaced during the Anglian (Marine Isotope Stage (MIS) 12) has recently been challenged by a view assigning each major till to a different glacial stage, before, during and after MIS 12. Between Trimingham and Sidestrand on the north Norfolk coast, datable organic sediments occur immediately below and above the glacial succession. The oldest glacial deposit (Happisburgh Till) directly overlies the ‘Sidestrand Unio‐bed’, here defined as the Sidestrand Hall Member of the Cromer Forest‐bed Formation. Dating of these sediments therefore has a bearing on the maximum age of the glacial sequence. This paper reviews the palaeobotany and describes the faunal assemblages recovered from the Sidestrand Unio‐bed, which accumulated in a fluvial environment in a fully temperate climate with regional deciduous woodland. There are indications from the ostracods for weakly brackish conditions. Significant differences are apparent between the Sidestrand assemblages and those from West Runton, the type site of the Cromerian Stage. These differences do not result from contrasting facies or taphonomy but reflect warmer palaeotemperatures at Sidestrand and a much younger age. This conclusion is suggested by the higher proportion of thermophiles at Sidestrand and the occurrence of a water vole with unrooted molars (Arvicola) rather than its ancestor Mimomys savini with rooted molars. Amino acid racemisation data also indicate that Sidestrand is significantly younger than West Runton. These data further highlight the stratigraphical complexity of the ‘Cromerian Complex’ and support the conventional view that the Happisburgh Till was emplaced during the Anglian rather than the recently advanced view that it dates from MIS 16. Moreover, new evidence from the Trimingham lake bed (Sidestrand Cliff Formation) above the youngest glacial outwash sediments (Briton's Lane Formation) indicates that they also accumulated during a Middle Pleistocene interglacial – probably MIS 11. All of this evidence is consistent with a short chronology placing the glacial deposits within MIS 12, rather than invoking multiple episodes of glaciation envisaged in the ‘new glacial stratigraphy’ during MIS 16, 12, 10 and 6. Copyright © 2009 John Wiley & Sons, Ltd.     

渤南洼陷沙四上段非均质性储层“二步建模”方法及应用

渤南洼陷沙四上段油气储层非均质性明显,砂层薄且与泥质间层分布,储层分布规律和空间叠置关系复杂。储层主要受深水盐湖、扇三角洲、滑塌浊积扇、近岸浊积扇、远岸浊积扇五类沉积相控制。利用先进的GridStrat建模软件,采用特殊的"二步建模"处理方法,根据不同沉积相的储层参数分布规律,进行井间插值或随机模拟,建立了沉积相、岩性、孔隙度、渗透率和产能系数模型。沉积相模型显示出扇三角洲及浊积扇是砂体分布的主体,且分布范围广;岩性模型显示出不同岩类的分布受沉积相带、构造位置及不同物源控制。孔、渗模型显示沉积相带和岩性是决定储层孔隙度与渗透率发育程度的主控因素。孔隙度决定了储油气空间的数量,渗透率决定了储层产能系数的大小。产能系数模型显示出产能潜力区为浊积扇和扇三角洲的叠合分布区。研究结论对油田开发部署起到积极指导作用。     

冀中坳陷饶阳凹陷留西地区古近系沙河街组沙三上亚段沉积相与隐蔽油藏

通过岩心观察和单井相分析,结合沉积背景资料,认为留西地区古近系沙河街组沙三上亚段发育辫状河三角洲相和湖泊相,以辫状河三角洲前缘亚相和滨浅湖亚相为主,主要发育辫状分流河道、越岸沉积、水下分流河道、河口坝、席状砂等微相。根据层序地层学基本原理,结合前人研究成果,认为本区沙三上亚段为一完整的三级层序,可划分为低位、湖侵和高位3个体系域,分别对应于沙三上亚段沉积时期的早期、中期和晚期,绘制了每个沉积阶段的沉积相图,在此基础上研究了沉积体系的平面展布特征。沙三上亚段沉积时期形成的北高南低的构造背景与辫状河三角洲近东西向展布的砂体形态相互配置,加之良好的油源供给,为后期成藏创造了条件。沙三上亚段沉积早期发育的辫状河三角洲前缘水下分流河道与河口坝砂体是主要的储集体,与沉积中期发育的烃源岩形成了十分有利的生储盖组合,具有优越的隐蔽油藏发育条件。总结了该区隐蔽油藏成藏的4种模式,确定留西地区中南部沙三上亚段沉积早期发育的辫状河三角洲前缘砂体是下一步隐蔽油藏勘探的有利目标。     

胜利油田孤岛油区馆陶组上段沉积结构单元

结构单元分析法(Architectural-Element Analysis)作为一种比较成熟的研究方法,已广泛应用于古代河流沉积研究.本文首次根据钻孔资料分析胜利油田孤岛油区馆陶组上段5～1+2砂层组河流沉积的结构单元.该段5～1+2砂层组岩石类型简单,可分为11个岩相类型.根据界面特征、岩相组合、内部几何形态、外部几何形态和垂向剖面特征等划分出6个结构单元:河道滞流沉积(CHL)、侧向加积砂坝(LA)、天然堤(LV)、决口扇(CS)、决口水道(CR)和洪泛平原细粒(FF).其中洪泛平原细粒(FF)、决口扇(CS)和侧向加积砂坝(LA)结构单元最为发育,其次是天然堤(LV)和决口水道(CR)结构单元,而河道滞流沉积(CHL)结构单元则不甚发育.决口扇(CS)结构单元是馆陶组上段砂体发育的主要单元之一,且富含油气资源.因此,进一步加强决口扇的研究对油气资源的勘察是十分必要的.     

东海陆缘(闽北段)晚第四纪沉积的硅藻学研究

对东海陆缘 (闽北段 )晚第四纪沉积 4口钻井岩心进行系统的硅藻分析研究,获得丰富的硅藻化石,共发现硅藻 117种和变种,分属于 33个属。根据剖面硅藻组合特征变化,结合最优分割法和对应序分法的计算机运算结果,可以详细划分为 12个硅藻带,自下而上为 :1.Cascinodiscusargus-Cos.wittiomus-Cyclotellastriata硅藻带,2.Cos.blandus-Cyclotellastriata硅藻带,3.Cos.excentricus-Trbliepteychuscocconiformis硅藻带,4.Gomphonema-Cos.blandus-Actnolychusralfsii硅藻带,5.Cos.-Cyclotellastriata-Actinocyclusralfsii硅藻带,6.Cos.-Actinolychusralfsii硅藻带,7.贫乏硅藻带,8.Cos.lineatus-Cos.rothii-Actinolyclusralfsii硅藻带,9.Gomphonema-Cyclotellastriata-Cocconeisplacentulavareuglypta硅藻带,10.Cos.rothii-Cyclotellastriata-Actinolychusralfsi,11.Cymbel laaffinis-Cyclotellastriata-Gomphonema硅藻带,12.Coscinodiscuswittinus-Cyclotellastriata-Epithemiahynd manii硅藻带,建立了该区晚第四纪硅藻组合序列,并探讨其相应的古环境演变。     

陆相渐新统划分中的问题及新进展

近年来国际上关于始新世－渐新世界线的研究取得了重大进展，其同位素年龄被确认为３４Ｍａ，北美哺乳动物年代表已据此重新厘定。通过对哺乳动物群的分析和对比，论证了我国原认为是早渐新世的乌兰戈楚期和呼尔井期的时代应改归晚始新世，原认为是中渐新世的三达河期的时代应为早渐新世。在亚洲始新世－渐新世的界线不是在乌兰戈楚期之末，而是在呼尔井期与三达河期之间。     

江西省晚白垩世周田组的再划分

江西自垩纪晚世地层中发育一套湖相细碎屑岩系，前人称之为周田组，一直沿用至今。作者认为前人对该岩石地层单位的定义不够准确或不够贴切。该组并不是“普遍含膏盐层”，而是仅在该组中部发育“膏盐层”，所以，有必要重新厘定；鉴于“膏盐层”的特殊性、且明显区别于组内其余部分岩性，因此，建议将该岩系新建为段级岩石地层单位——“会昌膏盐段”。这对当地乃至华南地区的陆相红盆的研究和地层划分对比、野外地质填图都具有重要意义，对寻找膏盐矿产资源也具有直接的指导作用。     

渤南洼陷沙四下亚段沉积时期古气候演化

正全球于古近纪发育PETM、ETM2、EECO、和MECO多个短期热气候事件(雷华蕊等,2018)。受热气候事件影响,渤南洼陷沙四下亚段沉积时期红层沉积发育并记录着热气候事件控制下古气候演化过程。立足于渤南洼陷沙四下亚段红层,恢复古气候演化过程,一方面可以点带面,揭示全球古近纪气候演化;另一方面为研究极端气候条件对湖盆沉积体系的控制作用奠定基础。     

‘Filament’ marker beds in the Karababa-A Member (Turonian) of the Arabian platform,SE Turkey: Palaeo-environmental significance,stratigraphy and correlation potential

A ‘filament’ event bed/level corresponds to the occurrence of thin elongate calcitic, shells, or plates of pelagic, bivalve or crinoidal, origin, within pelagic, laminated and organic-matter rich limestones. These organic-rich limestones had been generally deposited under hypoxic/anoxic conditions in an outer-ramp environment. These thin elongate, bivalve shells, or crinoidal plates, are found broken in small pieces, disintegrated, or simply preserved parallel to bedding as almost complete specimens. Such ‘filament’ beds were spotted in SE Turkey in deposits, namely the Karababa-A Member, around the Cenomanian-Turonian boundary (C/TB) and above. On a global scale, these filament event beds illustrate sea-level rise related to eustacy and/or climatic change. The abundance of filaments close to the C/TB is a biological marker of high organic productivity resulting from a climatic change to warmer conditions. The prevailing higher sea-level conditions were then favourable to the accumulation and preservation of organic-rich facies, characteristic of the Oceanic Anoxic Event 2 (OAE2). Using both biostratigraphic and carbon isotopic data, those deposits were dated from the latest Cenomanian-Turonian age. ‘Filament’ event beds were recorded in the same order, except for some small differences. A good number of these bio-events are global. Consequently, on a global scale, they are susceptible to constrain the C/TB, especially the base of the Turonian stage, with a significant degree of confidence.     

渤海湾盆地南堡凹陷南部深层沙一段优质碎屑岩储层特征及成因机制

利用岩芯、薄片、扫描电镜和分析化验等资料,对南堡凹陷南部深层古近系沙一段（沙河街组一段）优质碎屑岩储层特征进行了分析并揭示其成因机制。研究表明：①南堡凹陷南部沙一段优质碎屑岩储层属于低孔中渗储层,发育原生孔隙、次生孔隙和微裂缝;②沙一段沉积期处于强水动力沉积环境,辫状河三角洲前缘水下分流河道砂体普遍发育,岩性主要为中粗砂岩、含砾砂岩和砂砾岩等粗岩性,岩石类型主要为岩屑长石砂岩,石英、岩浆岩岩屑等刚性组分含量高,储层在强压实作用下仍保留了局部原生残余粒间孔,部分刚性组分强压条件下形成微裂缝;③沙一段与东三段为区域不整合接触,大气水的酸性流体在成岩初期以及烃源岩成熟之后产生的有机酸在成岩后期通过油源断裂和不整合面进入储层,造成长石、易溶碎屑等组分溶蚀形成次生孔隙,溶蚀作用不仅增加孔隙空间,而且扩大喉道宽度。结论认为：粗岩性和高刚性颗粒含量为原生孔隙的保存提供了物质基础;油源断层、不整合面为酸性流体的进入提供路径,促进了次生孔隙发育。