Oil migration driven by exhumation of the Canol Formation oil shale: A new conceptual model for the Norman Wells oil field,northwestern Canada     

《Marine and Petroleum Geology》2015

Thermal history, petroleum system, structural, and tectonic constraints are reviewed and integrated in order to derive a new conceptual model for the Norman Wells oil field, and a new play type for tectonically active foreland regions. The thermal history recorded by Devonian rocks suggests that source rocks experienced peak thermal conditions in the Triassic–Jurassic, during which time oil was likely generated. After initial oil generation and expulsion, the Canol Formation oil shale retained a certain fraction of hydrocarbons. The shallow reservoir (650–350 m) is a Devonian carbonate bank overlain by the Canol Formation and resides within a hanging wall block of the Norman Range thrust fault. Both reservoir and source rocks are naturally fractured and have produced high API non-biodegraded oil. Thrust faults in the region formed after the Paleocene, and a structural cross-section of the field shows that the source and reservoir rocks at Norman Wells have been exhumed by over 1 km since then.The key proposition of the exhumation model is that as Canol Formation rocks underwent thrust-driven exhumation, they crossed a ductile–brittle transition zone and dip-oriented fractures formed sympathetic to the thrust fault. The combination of pore overpressure and new dip-directed subvertical fractures liberated oil from the Canol Formation and allowed for up-dip oil migration. Reservoir rocks were similarly fractured and improved permeability enhanced charging and pooling of oil. GPS and seismicity data indicate that strain transfer across the northern Cordillera is a response to accretion of the Yakutat terrane along the northern Pacific margin of North America, which is also the probable driving force for foreland shortening and rock exhumation at Norman Wells.  相似文献   

鄂尔多斯盆地西缘惠安堡地区铀成矿特点   总被引：2，自引：1，他引：1  

李保侠  贾恒  于宏伟 《铀矿地质》2010,26(4):201-207

典型层间氧化带砂岩型铀矿产出于次造山带构造背景。惠安堡地区处于鄂尔多斯盆地西缘褶断带马家滩断褶带,传统理论认为这里不利于后生铀成矿作用的进行,但近几年的找矿实践证明该断褶带的铀成矿作用既有典型层间氧化带砂岩型铀矿的一些特点,也有自己的特殊性。该区的地层倾角较大,砂体厚度也较大;地下水近源、短途、双向径流,形成多个复杂的局部水动力系统;沿背斜东、西两翼发育的层间氧化带具有层数多、双向发育、期次多、氧化深度大、沿倾向延伸较短、纵横方向厚度变化快、连续性较差、地球化学分带不明显、水解蚀变作用弱等特点;铀矿化具有层数多、期次多、品位较低、厚度较小、矿化分散、深度较大、矿化主要受层间氧化带翼部控制、前锋成矿较弱、矿化纵横连续性差、矿后改造较强等特征。  相似文献   

Structural styles and tectonic evolution of the Kolia-Boboti sedimentary Basin,Kédougou-Kéniéba inlier,eastern Senegal     

Moussa Dabo  Tahar Aïfa 《Comptes Rendus Geoscience》2010,342(10):796-805

New structural data obtained on the Birimian terranes of the Kolia-Boboti sedimentary Basin, the eastern part of the Dialé-Daléma Supergroup in the Kédougou-Kéniéba inlier show two major phases of Eburnean compressional deformation: (1) a D1 phase of thrusting tectonics affected the Lower Birimian B1 tourmalinized sediments. This first tectonic phase is characterized by isoclinals overturned to recumbent folds P1 with N040° 20°NE trending axis, associated with axial plane schistosity S₀S₁ which is mainly transposed in the bedding; (2) a D2 phase of compressional (D2a) and transpressional (D2b) tectonics is responsible for the crossfolds P2a-P2b exhibiting curved axes. These P2 folds are associated with the major schistosity S₂, north-south to SW-NE trending, mainly dipping to the south-east. The S₂ schistosity is mostly displayed in the large shear zones corridors where it steeply dips locally toward the north-west. A north-west vergence thrusting phase (D2c) of flats and ramps, associated with reverse folds, represents the last Eburnean event. This geometrical feature is characteristic of a “positive flower structure”. These different Eburnean compressional phases are separated by extensional deformation which is characterized by sedimentary deposits and volcanic flows.  相似文献   

Structural and fluid evolution of Saraburi Group sedimentary carbonates,central Thailand: A tectonically driven fluid system     

《Marine and Petroleum Geology》2014

A stable isotopic study, focused on calcite cements, vein-fill calcite and various bioclasts was conducted on variably deformed and thrusted Lower and Middle Permian carbonates of the Saraburi Group. Samples were collected in quarry faces across 3 areas in the Saraburi–Lopburi region of central Thailand. Stable isotope crossplots (carbon and oxygen), using texture-aware isotope samples, defined variable, but related, fluid-cement histories, which are tied to regional burial and then orogenic overprints driven by the Indosinian (Triassic) orogeny. This was followed by telogenetic overprints, driven by late Cenozoic uplift. The studied carbonates were deposited along the western margin of the Indochina Block, where they were deposited as isolated calcareous algal, sponge and fusilinid-rimmed platforms on highs bound by extensional faults. The platform areas passed laterally and vertically into more siliciclastic dominated sequences, deposited in somewhat deeper waters within probable fault-bound lows. Regional post-depositional mesogenetic fluid-rock re-equilibration of the isotope values in ongoing calcite precipitates occurred until the matrix permeability was occluded via compaction and pressure solution. This regional burial regime was followed by collision of the Indochina and Sibumasu blocks during the Indosinian (Triassic) blocks, which drove a set of structurally focused (thrust-plane related) increasingly warmer set of fluids through the studied sequences. The final diagenetic overprint seen in the isotopic values of the latest calcite cements occurs in a telogenetic (uplift) setting driven by Cenozoic tectonics and isostatic uplift. Integration of isotope data with its structural setting establishes a clear separation in fluid events related to two time-separate tectonic episodes; its fluid chemistry defines the Permo-Triassic closure of the Paleotethys and its subsequent reactivation during the Tertiary collision of India and Asia. The C–O covariant plot fields in the Permian carbonates of central Thailand are so distinct that it is possible to use their signatures to separate burial from meteoric cements in drill cuttings and hence recognise equivalent subsurface unconformities and likely zone of porosity development in possible “buried hill plays in Thailand.  相似文献   

重力负载对库车褶皱冲断带盐构造的影响     

程海艳  李江海 《地质通报》2014,33(10):1502-1506

库车褶皱冲断带新生代沉积了库姆格列木群和吉迪克组2套盐岩,发育复杂的盐构造,重力负载对其形成和发育具有重要影响。利用水压头分析方法,分析了重力对库车褶皱冲断带盐构造的影响。重力负载对盐岩流动的影响包括重力扩张和沉积负载2种,重力扩张作用由盐岩受自身重力控制,而沉积负载作用由上覆沉积物重力作用控制。水压头分析表明在盐岩高程大的地方,其沉积负载往往更小。在重力扩张和沉积负载共同作用下,库车褶皱冲断带不会发生由盐岩自身重力而形成的重力扩张,重力负载对库车褶皱冲断带盐岩的影响仅表现为沉积差异负载作用。  相似文献   

广西全州小源铅锌矿地质特征、成因类型及找矿方向探讨          下载免费PDF全文

董秀英  唐朝霞  刘湘华  唐坤博  唐广明 《地质找矿论丛》2014,29(2):248-253

小源铅锌矿床是桂东北地区海洋山NE向铅锌铜成矿带中段的一个小型矿床。区内的中上奥陶统田岭口组上段和下泥盆统莲花山组是主要含矿地层;矿脉产于NE走向的张扭性正断层(断裂)中,构成多条平行等距排列的矿脉带;区内发现含矿脉带5条,圈定矿体7个;矿体在脉带中分布具有等距性。矿床成因类型为以岩浆热液为主的多源复合断裂控制热液脉型矿床。小源地区是寻找大型铅锌矿床有利地段。  相似文献   

Structural evolution of the Orange Basin gravity-driven system,offshore Namibia     

Jose de Vera  Pablo GranadoKen McClay 《Marine and Petroleum Geology》2010

The Orange Basin records the development of the Late Jurassic to present day volcanic-rifted passive margin of Namibia. Regional extension is recorded by a Late Jurassic to Lower Cretaceous Syn-rift Megasequence, which is separated from a Cretaceous to present day post-rift Megasequence by the Late Hauterivian (ca. 130 Ma) break-up unconformity. The Late Cretaceous Post-rift evolution of the basin is characterized by episodic gravitational collapse of the margin. Gravitational collapse is recorded as a series of shale-detached gravity slide systems, consisting of an up-dip extensional domain that is linked to a down-dip zone of contraction domain along a thin basal detachment of Turonian age. The extensional domain is characterized by basinward-dipping listric faults that sole into the basal detachment. The contractional domain consists of landward-dipping listric faults and strongly asymmetric basinward-verging thrust-related folds. Growth stratal patterns suggest that the gravitational collapse of the margin was short-lived, spanning from the Coniacian (ca. 90 Ma) to the Santonian (ca. 83 Ma). Structural restorations of the main gravity-driven system show a lack of balance between up-dip extension (24 km) and down-dip shortening (16 km). Gravity sliding in the Namibian margin is interpreted to have occurred as a series of episodic short-lived gravity sliding between the Cenomanian (ca. 100 Ma) and the Campanian (ca. 80 Ma). Gravity sliding and spreading are interpreted to be the result of episodic cratonic uplift combined with differential thermal subsidence. Sliding may have also been favoured by the presence of an efficient detachment layer in Turonian source rocks.  相似文献   

推覆构造的特征及其与油气的关系     

汤锡元 《地球科学与环境学报》1988,(2)

推覆构造是地壳中广泛发育的一种构造型式。逆冲断层常成带地平行排列,形成逆冲带和叠瓦构造。断层多呈上陡下缓或阶梯状,底部常有滑脱构造,并在深处常收敛在一个基底逆冲断层上。推覆构造还常与飞来峰、构造窗、叠瓦构造、牵引褶皱、后冲断层和平移断层等构造现象一起产出。推覆构造不仅扩大了找油的领域,它本身对油气的生成、储集、运移、圈闭和保存条件都有着重要的影响。虽然它们有时可造成某些对油气藏不利的因素,但更经常地则是造成油气藏形成的有利条件。当然,影响油气藏形成的因素十分广泛,它不仅限于推覆构造本身的某些特征,同时还决定于许多其它地质条件。因此,不同推覆构造或同一推覆构造的不同部位,其含油气远景也是很不相同的。  相似文献   

准噶尔盆地南缘前陆冲断带深层地质结构及对油气藏的控制作用:以霍尔果斯—玛纳斯—吐谷鲁褶皱冲断带为例     

马德龙  何登发  袁剑英  张虎权  潘树新  王宏斌  王彦君  魏彩茹  郭娟娟 《地学前缘》2019,26(1):165-177

准噶尔盆地南缘前陆冲断带位于天山北麓,在晚新生代强烈的挤压作用下,地表发育数排背斜带。由于构造变形复杂、地震反射成像质量较差,对深层地质结构争议较大,另外前新生代盆地原型对晚新生代以来的褶皱冲断带构造格局的影响也尚未探讨。霍尔果斯—玛纳斯—吐谷鲁(简称霍-玛-吐)褶皱冲断带位于准噶尔盆地南缘前陆冲断带地表第二排背斜带,利用最新采集和处理的地震反射资料,并结合地表地质露头建立深层构造模型;利用平衡地质剖面复原和构造物理模拟实验的方法探索早侏罗世盆地原型结构对现今褶皱冲断带构造格局的影响;在此基础上分析霍-玛-吐褶皱冲断带深层天然气富集规律。霍-玛-吐褶皱冲断带垂向上发育古近系—第四系逆冲推覆构造、中上侏罗统—白垩系构造楔和下侏罗统半地堑断陷结构。控制早侏罗世半地堑系统的高角度正断层在晚期挤压构造变形体系中充当逆断坡,并控制上覆构造楔和浅层逆冲推覆构造的发育。早侏罗世半地堑系统具有分段性,并通过侧向断坡进行连接,侧向断坡上覆地层发育南北向走滑调节断层。油气勘探现状表明,霍-玛-吐褶皱冲断带内部南北向走滑调节断层具有高效沟通下侏罗统烃源岩的特点,是控制天然气的富集的重要因素。以上研究表明,中西部陆内前陆冲断带前新生代古构造对于晚新生代挤压冲断构造格局和深层天然气富集规律具有重要意义。  相似文献   

滇西牟定—香格里拉电性剖面及深部构造   总被引：1，自引：0，他引：1       下载免费PDF全文

李文军  邵志刚  闻学泽  王启欣  王根成  张营  蒋长胜  王武星 《地球物理学报》2016,59(1):229-239

通过对滇西NW—SE向牟定—香格里拉大地电磁测深剖面的反演并结合地质构造、小震精定位资料,综合分析了剖面经过地区的深部构造.在滇西北地区深部发育一规模巨大的近水平产出地壳高导层,此高导层从香格里拉一直延伸到永胜盆地以东,沿剖面水平延伸超过200km.地壳高导层又可分为两段,两段高导层在剖面上形成两个香蕉型相连的复合形态,高导层之上的高阻体则形成两个碗型相连的复合结构,碗型内部有向东倾斜的相对低阻带存在.滇西北地区整体构造格架可以解译为一套两个主推覆面构成的叠瓦式推覆系统,两个主推覆面高低起伏形成总长度超过250km的底部滑脱带.第一个主推覆面的长度超过150km,并在丽江东部上翘到接近地表,小金河断裂是其延伸到地表的主要破裂带.第二个主推覆面长度超过120km,过程海断裂后上翘并在永胜以东地区出露地表.根据反向低阻带影像,可以推断推覆体反冲构造发育,在玉龙山至丽江以东和永胜盆地西缘至平川盆地东缘形成两处冲起构造.推覆面在剖面上呈现出平缓-陡峭-再平缓-再陡峭的断坪和断坡相间的阶梯状结构.  相似文献