豫西寒武纪叠层石的地层展布及控制因素分析

在河南省西部寒武系的渑池一登封小区,共出露23层叠层石,主要集中在馒头组、张夏组和三山子组。笔者在逐层详细描述该叠层石外部宏观形态和地层展布的基础上,分析了叠层石上下地层岩相变化,找出寒武纪叠层石地层展布的规律及其控制因素,认为影响叠层石地层展布的主要因素有沉积环境、水动力条件和后生动物干扰等,并讨论了叠层石生长与核形石、竹叶状灰岩和后生动物的相互关系,提出了叠层石与后生动物共生的生态位观点。     

湖底扇水道相控建模技术及应用

随着渤海勘探力度加强,大型湖底扇岩性圈闭逐渐成为新的勘探目标,但是湖底扇不同期次水道垂向相互叠合,部分水道下切,砂体展布以及砂体间的连通关系复杂。针对湖底扇储层具有非均质性强,储层刻画难度大的特点,以渤海垦利10-A构造为例,充分利用多种地震信息,高度综合地质、钻井、测井、地震等资料,将传统的“相控建模”思想引入湖底扇储层建模当中,提出了湖底扇储层相控建模新技术。该技术在对湖底扇沉积构型模式和富砂性深入研究的基础上,利用湖底扇储集相和三维甜点体属性进行双重控制和约束,在地质认识指导下,应用地质统计学理论和随机建模方法建立符合地质规律的三维岩相模型,在多次建模实现后求取砂岩概率体,完成对湖底扇水道的精细刻画,砂体连通性分析和储层预测。研究结果表明,该方法能有效地降低储层属性模拟的不确定性和多解性,提高储层预测的精度,为后期勘探布井奠定了基础。     

滇中地区梁山组黏土岩锂富集作用分析及找矿预测

滇中地区中二叠统梁山组富锂黏土岩分布于梁山期滇中古陆东侧河口湾、滨海平原沼泽区的泥坪带. 梁山组黏土岩由4种岩性类型组成: 灰-灰褐色含铁铝土(矿)岩、灰白杂红色高岭石黏土岩、灰-灰绿色黏土岩、灰黑-黑色水云母碳质黏土岩. 研究发现, 半咸水向咸水转变、弱氧化-还原、低能、滞留局限的古地理环境有利于形成富锂黏土岩. 在稳定的大地构造环境, 温暖、潮湿的古气候, 丘陵为主的古地形条件下, 滇中古陆的寒武系-泥盆系镁质碳酸盐岩在次生风化作用下形成的富锂黏土, 经过搬运、沉积作用形成富锂黏土岩. 在昆明市东川-富民、玉溪市红塔-建水、丽江市永胜-宁蒗地区具较好的富锂黏土岩找矿潜力.     

下扬子下寒武统岩相古地理及烃源岩条件研究

以下扬子下寒武统为研究对象,利用野外露头、岩心、岩石微观分析、有机地球化学等资料,在地层对比基础上,开展了下扬子下寒武统岩相古地理研究及烃源岩条件评价。结果表明：下扬子下寒武统主要发育硅质岩、硅质泥页岩、碳质泥页岩、灰质泥页岩、泥灰岩、白云岩6种岩石类型;地层可划分为3段,其中安吉-石台-上海地区三段发育齐全,其他地区一段大部分缺失,二段存在不同程度缺失;沉积相主要发育盆地、陆棚、斜坡、台地边缘、局限台地5种类型;烃源岩主要分布于石台-安吉、滁州-盐城、德兴-桐庐盆地相及周边陆棚相,石台-安吉地区是烃源岩发育最有利区,泥岩厚度300~700m,TOC为3%~9%,平均4.5%~5.76%;德兴-桐庐地区泥岩厚度200~400m,TOC为3%~9%,平均4.96%;滁州-盐城凹陷泥岩厚度50~200m,TOC为2%~4%。下扬子下寒武统烃源岩干酪根类型全部为Ⅰ型,有机质组分主要为腐泥组,以藻类体为主,含少量腐泥无定形体。下扬子下寒武统烃源岩均处于过成熟演化阶段,总体上由皖南盆地区向两侧台地逐渐降低,九江、景德镇、黄山及开化淳安地区受火山岩影响Ro在4.0%以上;安庆-溧阳-南通以南,湖州-苏州以西处于盆地、陆棚及斜披部位,埋深大,Ro为3.0%~4.0%;潜山、南陵、无为、金坛及苏北中新生代凹陷由于后期埋深较大,Ro在3.0%以上;其他区域Ro为2.0%~3.0%。     

滇黔桂“金三角”地区晚三叠世地层碎屑物源示踪

三叠系是滇黔桂分布最广泛的岩系,赋存卡林型金矿等各种低温矿产。在前人研究基础上,运用LA-ICP-MS分析技术,对滇黔桂"金三角"地区的碎屑锆石进行了U-Pb测年。结果显示,大部分锆石具岩浆环带,Th/U值大于0.4,锆石U-Pb年龄集中在308~396 Ma、440~680 Ma、727~930 Ma、1004~1266 Ma、1400~1880 Ma、2360~2724 Ma六个区段。通过对比研究区及周围地块的碎屑锆石年龄分布特征,结合研究区岩相古地理、古海流及古流向,综合分析认为,研究区物源以越北古陆为主,同时湘粤桂构造山系和云开地区也可能提供了部分物源。该物源印证了古特提斯洋在印支期逐渐闭合,华南陆块与印支地块沿松马缝合带发生碰撞。     

Correlation of the Jurassic-Cretaceous siliceous-volcanogenic sediments in northwestern surroundings of the Pacific (Koryak Upland)

In distribution areas of the Pekul’neiveem and Chirynai formations customary distinguishable in the Koryak Upland, complicated tectonostratigraphic units are composed of alternating thrust sheets of different lithologic composition and age, which are juxtaposed because of widespread thrust faulting, as is proved by the radiolarian analysis. Nineteen radiolarian assemblages of different age are first established here in the Lower Jurassic-Hauterivian succession of siliceous-volcanogenic sediments. In the Lower Jurassic interval, the lower and upper Hettangian, lower and upper Sinemurian, and Pliensbachian beds are recognized. Paleontological characterization is also presented for the Aalenian (or Toarcian?-Aalenian), upper Bajocian, lower and upper Bathonian, and Callovian beds of the Middle Jurassic. Within the Upper Jurassic, the Oxfordian-early Kimmeridgian, late Kimmeridgian-early Tithonian, Tithonian, and late Tithonian-early Berriasian radiolarian assemblages are distinguished. The late Berriasian-early Valanginian, middle-late Valanginian, and Hauterivian radiolarian assemblages are first recognized or compositionally revised. Radiolarians and lithofacies data are used to correlate the tectonostratigraphic units and individualize the jasper-alkali basaltic (lower Hettangian), chert-terrigenous (Hettangian-Sinemurian), jasper-cherty (Pliensbachian-Aalenian), jasper (Bajocian-Hauterivian), jasper-basaltic (upper Bajocian-Valanginian), Fe-Ti basaltic (upper Bajocian-Bathonian), tuffitejasper-basaltic (Bathonian-Hauterivian), and terrigenous-volcanogenic (Bajocian-Valanginian) sequences. The correlation results are extrapolated into other continental areas flanking the Pacific, i.e., to the western Kamchatka, northern and northwestern coastal areas of the Sea of Okhotsk, where the analogous radiolarian assemblages are characteristic of comparable allochthonous units of terrigenous-siliceous-volcanogenic sediments.     

Palaeogeography and clay mineralogy of mid-Cretaceous flysches in the Gibraltar Arc area

A combined sedimentological and mineralogical study of several mid-Cretaceous sequences of the western Betic Cordillera and northern Rif has lead to the distinction of three main palaeogeographic areas. The basins of these areas received influxes of terrigenous sediments from different source areas. The southern Iberian margin was fed from the Iberian palaeocontinent and its clay-mineral association is characterized by a high content of well crystallized illite and kaolinite; the distal part of this margin was locally starved of continental sedimentation, but contains a considerable clayey contribution, probably oceanic in origin, made up mainly of smectites, illite and palygorskite. The sediments in the North African margin and the southern part of the North African Flysch Trough came from the African continent, the typical Aptian-Albian clay-mineral association being well crystallized illite, illite-smectite mixed layers, kaolinite, chlorite and lesser quantities of vermiculite. The terrigenous supply to the Mauritanian Realm of the North African Flysch Trough came from the Meso-Mediterranean terrane, and its usual Aptian-Albian clay association is illite, vermiculite, illite-smectite mixed layers and kaolinite. A significant change in the clay mineralogy occurred during the late Albian-early Cenomanian in the two former areas, consisting of a decrease in the detrital supply and a concomitant increase in smectites and palygorskite.The sedimentological and mineralogical evolution of this area was controlled by a combination of tectonic, eustatic and climatic changes in the westernmost Tethys during the mid-Cretaceous.     

Carbon isotope composition of the Lower Triassic marine carbonates, Lower Yangtze Region, South China

The Early Triassic is a critical period in earth his- tory. A series of events such as volcano eruptions[1,2], sea-level fluctuations, changes in environmental con- ditions[3], mass extinctions[4,5] as well as global negative carbon isotope excursions[6-9] have been discovered in the uppermost Permian or across the Permian-Triassic boundary. Large scale sea-level rise[10-12], restoration of environment conditions, re- covery of ecosystem[13], including gradual carbon iso- tope rise[14] occur…     

北祁连东部石炭纪岩相古地理

〗通过对石炭系实测剖面岩石的岩性、岩相、结构构造、粒度、古生物组合和古生态等特征的综合分析,利用石油勘探成果,研究了北祁连东部石炭纪岩相古地理。早石炭世早期,秦岭海域海水以天水—静宁古海峡为通道,向北侵入本区,形成由鄂尔多斯、阿拉善和陇西三大古陆围限的祁连海海湾沉积区,以咸化泻湖相、滨浅海相沉积为主,早石炭世晚期,海侵进一步扩大,以滨浅海相碎屑岩、碳酸盐岩沉积为主。晚石炭世海盆继续向东、向北扩展,海侵次数增多,形成了多个以碎屑岩为主夹灰岩沉积的海侵海退旋回,晚石炭世晚期太原组沉积时期,海水向东与华北海相连,成为广阔的陆表海沉积。中部地区存在近东西向分布的链岛状古隆起及水下隆起,古地形具西高东低、北高南低的特征。     

鄂尔多斯盆地西缘麻黄山地区延8储层特征

通过对延8储层铸体薄片、扫描电镜、孔渗测定、压汞资料等分析,延8储层具有以下特征:研究区北边富长石、南边富石英,具有不同的物源;砂岩粒度以中粒为主,细粒和粗粒次之;主要的储集空间为粒间孔和粒内溶孔;由于大量的长石、岩屑被溶,孔隙度、渗透率不呈正态分布,均偏大,溶蚀作用形成的大量微孔造成高束缚水饱和度,产纯油或含水率极低;砂体厚度、岩石相和成岩作用共同控制着储集层的物性。结果表明,位于河道中部弱胶结的中砂岩具有良好的储集性能。