Distribution and sedimentary characteristics of tsunami deposits along the Cascadia margin of western North America   总被引：1，自引：0，他引：1  

Robert Peters  Bruce Jaffe  Guy Gelfenbaum 《Sedimentary Geology》2007,200(3-4):372-386

Tsunami deposits have been found at more than 60 sites along the Cascadia margin of Western North America, and here we review and synthesize their distribution and sedimentary characteristics based on the published record. Cascadia tsunami deposits are best preserved, and most easily identified, in low-energy coastal environments such as tidal marshes, back-barrier marshes and coastal lakes where they occur as anomalous layers of sand within peat and mud. They extend up to a kilometer inland in open coastal settings and several kilometers up river valleys. They are distinguished from other sediments by a combination of sedimentary character and stratigraphic context. Recurrence intervals range from 300–1000 years with an average of 500–600 years. The tsunami deposits have been used to help evaluate and mitigate tsunami hazards in Cascadia. They show that the Cascadia subduction zone is prone to great earthquakes that generate large tsunamis. The inclusion of tsunami deposits on inundation maps, used in conjunction with results from inundation models, allows a more accurate assessment of areas subject to tsunami inundation. The application of sediment transport models can help estimate tsunami flow velocity and wave height, parameters which are necessary to help establish evacuation routes and plan development in tsunami prone areas.  相似文献   

白音查干凹陷达尔其油田沉积相与油(气)分布   总被引：5，自引：0，他引：5  

周连德  徐国盛  王威 《物探化探计算技术》2007,29(5):405-410

达尔其油田腾格尔组和都红木组一段具有近物源、多期次、快速沉积的特征,沉积相的类型多而复杂。勘探实践表明:该区"增储上产"的关键是寻找好的沉积微相中的优质储层。通过研究认为,达尔其地区主要发育湖泊、辫状河三角洲、冲积扇三类的沉积体系,好的沉积(微)相控下的储集层普遍具有高孔、高渗的特点,与产能具有良好的匹配关系。浅湖砂坝、席状砂、深湖浊积扇、深湖 浊积砂、辫状河水道和滑塌浊积扇是达尔其油田主力产油沉积(微)相。冲积扇~辫状河三角洲~湖泊这种过渡相沉积影响着该区油(气)分布,使达尔其油田油(气)聚集区在斜坡上呈NE-SW方向分布三个油气聚集带:高部位断背斜型油气聚集带、中部位岩性~构造型油气聚集带和低部位构造~岩性型油气聚集带,且在达尔其东区和西区油气分布各有差异。低部位构造~岩性型油气聚集带中浊积砂(扇)体、浅湖砂坝等隐蔽性油(气)藏是今后油气勘探的重要目标。  相似文献   

黄河口凹陷A区古近系沙河街组三段沉积相   总被引：3，自引：0，他引：3  

李慧勇  辛仁臣  李强  马洪  周心怀  徐长贵 《古地理学报》2007,9(1):25-32

通过岩心观察描述和沉积相分析，结合地震、测井、录井、分析化验资料综合分析结果表明：黄河口凹陷A区沙河街组三段发育扇三角洲相、湖底扇相和湖泊相。沙三段下亚段沉积相特征在沙三段沉积时期具有代表性。沙三段下亚段主要储层沉积相类型为扇三角洲相和湖底扇相。扇三角洲相划分为扇三角洲平原、扇三角洲前缘和前扇三角洲3个亚相。扇三角洲平原亚相由泥石流和水道沉积组成。扇三角洲前缘亚相由近端坝和远端坝沉积组成。湖底扇相可分为内扇、中扇和外扇3个亚相。内扇主要由滑塌堆积和碎屑流沉积组成，中扇主要由碎屑流和浊流沉积组成，外扇主要由浊流沉积组成。沙三段下亚段沉积时期，沉积相的平面展布具有一定的规律性，表现为：靠近南部盆缘断裂发育扇三角洲相，向湖方向发育湖底扇相，向北逐渐过渡为湖泊相。沙三段下亚段沉积时期，盆地明显为南陡北缓的箕状断陷湖盆，陡坡带活动盆缘断裂控制了扇三角洲相的分布。  相似文献   

吉林新立油田下白垩统泉头组成岩储集相及储集空间演化     

胡海燕  彭仕宓  卢春慧  齐耀春  胡景春  李国 《古地理学报》2007,9(1):97-106

吉林新立油田位于吉林省松原市郭县以北新庙乡境内。综合应用25口取心井薄片、镜质体反射率、铸体、电镜、X衍射等岩心分析资料，研究了泉头组的成岩作用、成岩演化序列、成岩阶段划分及储集空间类型。根据成岩作用及特有的储集空间组合，划分了4种成岩储集相类型，即A相(不稳定组分强溶解次生孔隙成岩储集相)、B相(中等压实弱-中胶结混合孔隙成岩储集相)、C相(强压实中等胶结残余粒间孔成岩储集相)、D相(碳酸盐强胶结微孔隙成岩储集相)；并阐述了各类成岩储集相的特征，其中A相储集物性最好，B相次之，C相较差，D相最差。最后探讨了泉头组储集空间演化，在中成岩阶段A期形成了大量次生溶蚀孔隙，为首次在该区泉头组特低渗储层中预测相对有利的成岩储集相带提供了研究思路和科学依据，也为改善特低渗油田的开发效果奠定了坚实的地质基础。  相似文献   

安徽定远县八里张石膏矿区含盐岩系沉积特征与矿床成因探讨     

刘青  朱琨 《华北地质》2007,30(2):115-120

八里张石膏矿位于合肥盆地北缘,赋存于古近系定远组含盐岩系。古近系定远组是安徽重要的陆相含盐建造。文中结合矿区地质背景,着重从沉积相特征的角度,通过对定远组含盐岩系的岩相特征、沉积规律、形成条件以及河湖相沉积特征规律的分析,对矿区的矿床成因也做了初步分析。认为矿区含盐岩系由河湖相沉积组成,属陆相盐湖沉积,同时在盐湖的形成过程中,盐盆受断裂控制。  相似文献   

准噶尔盆地西缘车排子地区油气成藏的主控因素   总被引：2，自引：0，他引：2  

洪太元  王离迟  孟闲龙  吴疆 《新疆地质》2007,25(4):389-393

钻探结果表明,准西车排子地区油藏具有"上稀下稠、南稀北稠"的油藏分布特征,成藏条件复杂,该区油藏是典型的它源型油气藏,油气来源于东部的昌吉凹陷及南部的四棵树凹陷.通过对已钻探井的系统分析发现,以P2、P8井为代表的新近系沙湾组稀油油藏均分布于滨浅湖相的滩坝砂岩中,油藏明显受沉积相的控制,此外,该区成藏还受输导体系以及油气优势运移路径的控制,这3方面的因素构成了该区油气成藏的主控因素.通过对车排子地区油气成藏主控因素的研究,以期对该区的油气勘探有所裨益,提高勘探的经济效益.  相似文献   

Cenozoic graben facies in the Middle Amur sedimentary basin as inferred from seismic and electrical exploration     

T. V. Merkulova  E. P. Razvozzhaeva 《Russian Journal of Pacific Geology》2007,1(4):335-351

Most of the grabens of the Middle Amur sedimentary basin (MASB) are usually characterized by similar structures typical of continental rifts. Based on models elaborated for the sedimentary infill in well-studied rift basins, seismic facies developed in grabens of the MASB are first analyzed. The analysis revealed seismic facies characteristic of different parts of asymmetrical basins: facies of fans developed on steep slopes and facies of coastal shoals, alluvial plains, and deltas occurring on gentle slopes. Seismic facies peculiar of deep lacustrine settings that are considered promising with respect to oil-and gas-bearing source rocks is recognized. Correlation of seismic and drilling data confirms the correctness of the interpretations and shows that boreholes penetrated a thin sequence of deep-water lacustrine sediments. Using the vertical electrical sounding method, a low-resistivity sequence that is most promising for discovery of lacustrine sediments is defined in the southwestern and eastern parts of the MASB. The lowest values of the specific resistivity in this sequence (7–8 Ohm · m) are recorded in its southeastern part, where a borehole partly recovered a relatively thick silty-clayey sequence.  相似文献   

Whole-rock, Phosphate, and Silicate Compositional Trends across an Amphibolite- to Granulite-facies Transition, Tamil Nadu, India   总被引：2，自引：0，他引：2  

Hansen  Edward C.; Harlov  Daniel E. 《Journal of Petrology》2007,48(9):1641-1680

Chemical trends from north (amphibolite facies) to south (granulitefacies) along a 95 km traverse in Tamil Nadu, Southern India,include: whole-rock depletion of Rb, Cs, Th and U, enrichmentin Ti and F, and depletion in Fe and Mn in biotite and amphibole;increases in Al and decreases in Mn in orthopyroxene; enrichmentof fluorapatite in F. K-feldspar blebs are widespread alongquartz–plagioclase grain boundaries, and could indicateeither partial melting or metasomatism. In the northernmostportion of the traverse the principal rare earth element (REE)-bearingminerals are allanite and titanite. South of a clinopyroxeneisograd, monazite grains independent of fluorapatite are themajor REE- and Th-bearing phase. Further south independent monaziteis rare but Th-free monazite inclusions are common in fluorapatite.During prograde metamorphism, independent monazite was replacedby REE-rich fluorapatite in which the monazite inclusions laterformed. The loss of independent monazite was accompanied bya loss of whole-rock Th and possibly a small depletion in lightREE. Most mineralogical features along the traverse can be accountedfor by progressive dehydration and oxidation reactions. Trace-elementdepletion is best explained by the action of an externally derivedlow H₂O activity brine migrating from a source at greater depth,possibly preceded or accompanied by partial melting. KEY WORDS: granulite facies; charnockite; metasomatism; Archean; Tamil Nadu, India; fluorapatite; monazite; allanite; titanite; biotite  相似文献   

新化—城步地区泥盆纪沉积相及台盆演化     

刘五一 《湖南地质》1991,(3)

新化—城步地区泥盆纪沉积相类型较丰富,可划分7个相组、17个相。最突出的特征是在两个碳酸盐台地之间发育有一较深水的盆地,即台盆。西部的碳酸盐台地与台盆之间的边缘无明显的陡坡,属于J.F.Read所称的碳酸盐等斜缓坡。区内沉积相,尤其是在棋梓桥晚期——佘田桥期,大体上呈北北东向展布。构成这一特殊沉积格局的主要原因是该区沉积相受加里东运动期间形成的基底断裂控制。区内台盆演化可分为初始台盆、台盆扩展、台盆稳定、台盆最大扩展、台盆收缩变浅、台盆残余凹陷等六个阶段。  相似文献   

川东北前陆盆地须家河组层序-岩相古地理特征   总被引：27，自引：3，他引：24  

高红灿  郑荣才  柯光明  文华国 《沉积与特提斯地质》2005,25(3):38-45

根据控制高分辨率层序的构造和天文因素将川东北前陆盆地晚三叠世须家河期划分为2个超长期、5个长期、18个中期及数十个短期旋回层序,并分析了须家河组超长期层序的岩相古地理特征与演化.在SLSC1超长期旋回时期,米仓山-大巴山构造山系尚处于低幅稳定隆升状态,而龙门山构造山系的逆冲推覆作用较为活跃,川东北前陆盆地属于受龙门山逆冲推覆作用远端效应影响的前陆斜坡,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SLSC2超长期旋回时期,龙门山逆冲推覆进一步增强,同时,米仓山-大巴山开始进入逆冲推覆前的强烈构造隆升阶段,川东北前陆盆地有较大幅度的持续拗陷沉降,在继承SLSC1古地理演化的基础上,形成了以沿龙门山和米仓山-大巴山两逆冲推覆带前缘广泛发育的、以巨厚块状砾岩为特征的大型冲积扇沉积体系.  相似文献