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941.
准噶尔盆地南缘白垩系原油成藏特征   总被引:6,自引:0,他引:6  
准噶尔盆地南缘地区的油气勘探与石油地质研究长期以来以二叠系和侏罗系含油气系统为主。本文在前人工作基础之上,从烃源岩、油源和油气运聚三方面,首次比较系统地剖析了本区的白垩系原油成藏特征。研究结果表明,白垩系烃源岩的生烃和油气聚集中心位于玛纳斯—呼图壁一带,烃源层系最大厚度可超过250 m,有机质类型以Ⅰ—Ⅱ1型为主,在古近纪末进入成熟排烃阶段,是本区不可忽视的一套重要烃源岩。白垩系原油纵向上主要聚集于古近系安集海河组到白垩系吐谷鲁群储层流体系统,可能存在三期油气运聚,第一期在早更新世晚期,以流体系统内部的白垩系原油运聚成藏为主,第二期是在中更新世晚期至晚更新世早期,白垩系原油,以及成熟度相对较低的古近系原油在此流体系统内部发生混合,第三期在晚更新世末期,以油气(并以侏罗系天然气为主)在垂向上沿断层的调整为特征,最终形成了复杂的多源、多层系油气分布态势。综合认为,需要充分重视白垩系原油在本区的勘探和研究。  相似文献   
942.
Iceland has been subjected to destructive earthquakes and volcanic eruptions throughout history. Such events are often preceded by changes in earthquake activity over varying timescales. Although most seismicity is confined to micro-earthquakes, large earthquakes have occurred within populated regions. Following the most recent hazardous earthquakes in 2000, the Icelandic Meteorological Office (IMO) developed an early warning and information system (EWIS) Web-site for viewing near-real-time seismicity in Iceland. Here we assess Web-site usage data in relation to earthquake activity, as recorded by the South Iceland Lowland (SIL) seismic network. Between March 2005 and May 2006 the SIL seismic network recorded 12,583 earthquakes. During this period, the EWIS Web-site logged a daily median of 91 visits. The largest onshore event (M L 4.2) struck 20 km from Reykjavík on 06 March 2006 and was followed by an immediate, upsurge in usage resulting in a total of 1,173 unique visits to the Web-site. The greatest cluster of large (≥M L 3) events occurred 300 km offshore from Reykjavík in May 2005. Within this swarm, 9 earthquakes ≥M L 3 were detected on 11 May 2005, resulting in the release of a media bulletin by IMO. During the swarm, and following the media bulletin, the EWIS Web-site logged 1,234 unique visits gradually throughout the day. In summary, the data reveal a spatial and temporal relationship between Web-site usage and earthquake activity. The EWIS Web-site is accessed immediately after the occurrence of a local earthquake, whereas distant, unfelt earthquakes generate gradual interest prompted by media bulletins and, possibly, other contributing factors. We conclude that the Internet is a useful tool for displaying seismic information in near-real-time, which has the capacity to help increase public awareness of natural hazards.  相似文献   
943.
The sedimentary succession of the Col de la Plaine Morte area (Helvetic Alps, central Switzerland) documents the disappearance of the northern Tethyan Urgonian platform in unprecedented detail and suggests stepwise platform demise, with each drowning phase documented by erosion and phosphogenesis. The first identified drowning phase terminated Urgonian carbonate production in a predominantly photozoan mode. Using a correlation of the whole-rock δ13C record with the well-dated record from SE France, its age is inferred to as Middle Early Aptian (near the boundary between the weissi and deshayesi zones). A subsequent drowning phase is dated by ammonites and by a correlation of the whole-rock δ13C record as Late Early Aptian (late deshayesi to early furcata zone). A third drowning phase provides an ammonite-based age of Early Late Aptian (subnodosocostatum and melchioris zones) and is part of a widely recognized phase of sediment condensation and phosphogenesis, which is dated as latest Early to Middle Late Aptian (late furcata zone to near the boundary of the melchioris and nolani zones). The fourth and final drowning phase started in the latest Aptian (jacobi zone) as is also indicated by ammonite findings at the Col de la Plaine Morte. The phases of renewed platform-carbonate production intervening between the drowning phases were all in a heterozoan mode.

During the ultimate drowning phase, phosphogenesis continued until the Early Middle Albian, whereas condensation processes lasted until the Middle Turonian. Coverage of the external margin of the drowned Urgonian platform by a drape of pelagic carbonates started only in the Late Turonian. During the Santonian, the external part of the drowned platform underwent normal faulting and saw the re-exposure of already lithified Urgonian carbonates at the seafloor.

Based on the here-inferred ages, the first drowning phase just precedes oceanic anoxic episode 1a (OAE 1a or “selli event”) in time, and the second drowning phase partly overlaps with OAE 1a. The onset of the third drowning event slightly predates two further periods of increased organic-matter accumulation in the Vocontian Basin (Noir and Fallot levels), and the onset of the fourth and final drowning phase may coincide with two further periods of increased organic-matter accumulation in the Vocontian Basin (Jacob and Kilian levels, part of OAE 1b). These correlations indicate a relationship between the so-called anoxic episodes and the stepwise demise of the Urgonian platform, even if the onset of environmental change is registered earlier on the platform than in basinal sediments.  相似文献   

944.
The effects of hydrologic cycle change (caused by human activity and global climate change) on ecosystems attract the increasing attention around the world. As a result of impounding of the Three Gorges Dam (TGD), climate change and sand mining, the dry season of Poyang Lake and Dongting Lake (China’s two largest freshwater lakes) came early after the TGD impoundment. It was the primary cause of the increasing need for sluice/dam construction to store water in the Lakes and attracted increasing attention. In this paper, we compared the landscape pattern between three hydrologic years with early dry season (EY) and three normal hydrologic years (NY) of each lake by remote sensing technology, to reveal the effect of early dry season on landscape pattern. The results showed that early dry season caused expanding of Phalaris to mudflat zone in Poyang Lake, while caused expanding of Carex to Phalaris zone and expanding of Phalaris to mudflat zone in Dongting Lake. In landscape level, there was no significant difference in landscape grain size, landscape grain shape, habitat connectivity and landscape diversity between EY and NY in the two lakes. While in habitat class level, there were significant changes in area of mudflat and Phalaris and grain size of mudflat in Poyang Lake, and in area of Carex, grain size of Phalaris and grain shape of Carex and Phalaris in Dongting Lake. These changes will impact migrating birds of East Asian and migratory fishes of Yangtze River.  相似文献   
945.
目的 探讨合并瘢痕子宫患者采用药物流产终止早期妊娠的治疗效果。方法 收集2014年1月~2015年12月新疆医科大学第二附属医院妇科合并瘢痕子宫患者早期妊娠采用药物流产的病例215例作为病例组,未合并瘢痕子宫者574例作为对照组,均给予相同剂量的米非司酮及米索前列醇进行药物流产,观察两组完全流产、不全流产、流产失败的概率,孕囊排出时间,阴道流血量及不良反应。结果 病例组药物流产成功率为87.4%,对照组的药物流产成功率为89.1%,二者差异无统计学意义;病例组在服用米索前列醇后孕囊排出时间平均为4.24h,对照组为2.57h,二者比较差异有统计学意义(P<0.05);两组患者出血量均集中在50~80ml,其中病例组中阴道出血量>80ml占21.4%,对照组为13.3%,且二者比较差异有统计学意义(P<0.05);两组均未发生严重的不良反应,主要为恶心、呕吐、腹泻等胃肠道反应,差异无统计学意义(P>0.05)。结论 合并瘢痕子宫患者采用药物流产术终止早期妊娠是可行的,但需密切观察患者服药后孕囊排出时间、阴道出血量及药物的不良反应。  相似文献   
946.
宁芜火山岩的地球化学特征及其意义   总被引:40,自引:30,他引:40  
王元龙  张旗等 《岩石学报》2001,17(4):565-575
宁芜早白垩世火山岩由中基性成分组成,与碱性玄武岩比较,火山岩贫Ti,Fe,富K和LREE,Na2O/K2O近似等于1,在SiO2-K2O图中龙王山组的全部和大王山组的大部落入橄榄玄粗岩区域,属于橄榄玄粗岩系列,为富集LILE和水的地幔部分熔融的产物。宁芜火山岩产于板内环境,富钾质岩浆的形成可能与软流圈地幔上涌和岩石圈的伸展-减薄或裂谷作用有关。宁芜火山岩富集大离子亲石元素,亏损高场强元素,Ti,Nb(Ta)具负异常。宁芜火山岩底部的龙王山组和主体大王山组具有不同的地球化学特征:与大王山组相比,前者更富Rb,Ba,K,而相对贫LREE(La,Ce,Nd),Eu,Sr,Isr较高,εNd(t)较低。由于龙王山组层位低,大王山组层位高,不可能解释为分离结晶作用的结果,而只能说明在火山岩喷发的早期阶段(龙王山组),岩浆穿过陆壳上升过程中与围岩发生过混染作用,从围岩中带入较多的K、Rb,Ba等大离子亲石元素,从而使得Isr较高和εNd(t)较低。龙王山组SiO2-K2O不具相关性也说明陆壳混染的影响。至宁芜火山岩喷发的极盛时期(大王山组),岩浆与围岩的混染程度降低,Isr和Nd(t)值更接近岩浆的初始组成。据了解,在长江中下游地区有许多晚中生代的埃达克质岩出露,埃达克质岩来自加厚的陆壳底部,需要很高的温度才能使下地壳基性岩发生部分熔融。宁芜一带火山岩的大规模喷出,表明在早白垩世初期该区地幔处于十分活跃的状态,可能有大量橄榄玄粗质岩浆底侵到下地壳底部,烘烤下地壳使之熔融形成埃达克质熔浆。  相似文献   
947.
吉利明  雷怀彦 《地层学杂志》1997,21(1):32-38,T001
对甘肃南部徽成盆地东河群进行了孢粉研究,在上部的化垭组首次发现了一些孢粉化石。孢粉组合以Cicatricosisporites Hsuisporites Clasopolis为代表,蕨类植物孢子占明显优势,以海金砂科、水龙骨科和卷柏科为主;裸子植物花粉以掌鳞杉科最常见,还有松科及麻黄科花粉。经孢粉组合特征和属种地史分布对比分析,认为化垭组的地质时代属早白垩世,可能为早白垩世中期,东河群的上界也为这一时期  相似文献   
948.
四川都江堰市、彭州、什邡地区的侏罗系   总被引:16,自引:0,他引:16  
石和 《地层学杂志》1997,21(3):192-202
龙门山中段都江堰市、彭州市、什邡县等地的侏罗系十分发育,呈NE-SW向展布。在1991~1995年1/5万区调期间,从这个地区测制的一些侏罗系剖面中划分出了千佛崖组、沙溪庙组、遂宁组和莲花口组4个岩石地层单位,并与邻区相应地层单位进行了对比,总结了它们的岩石特征和相变;根据ESR(电子自旋共振)测年资料讨论了侏罗纪的年代地层划分;并简要叙述了千佛崖期湖相、沙溪庙—遂宁期河流相和莲花口期洪积相(冲积扇相)的划分依据。  相似文献   
949.
江苏句容早三叠世鱼类化石之发现及其意义   总被引:1,自引:0,他引:1  
记述了江苏句容下三叠统青龙组下三叠统青龙组下部地层中发现的软骨硬鳞鱼类一新种-江苏裂齿鱼和半椎鱼类一新种-句容鳞齿鱼化石,并讨论了其分类特征、生存环境及化石埋藏状况。  相似文献   
950.
本文首次报道东海陆架拗陷带早第三纪玄武岩的发现及邻区有关玄武岩同位素体系分析结果。初步研究表明东海玄武岩为晚渐新世喷发产物,源自与岩石圈有亲缘关系的富集地幔,EMI-LOMU端元在其源区中起主导作用,其深部很可能具古老大陆基底,这一推论为研究华南地区构造演化提供了新的制约。  相似文献   
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