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941.
The Bauru Basin was one of the great Cretaceous desert basins of the world, evolved in arid zone called Southern Hot Arid Belt. Its paleobiological record consists mainly of dinosaurs, crocodiles and turtles. The Bauru Basin is an extensive region of the South American continent that includes parts of the southeast and south of Brazil, covering an area of 370,000 km2. It is an interior continental basin that developed as a result of subsidence of the central-southern part of the South-American Platform during the Late Cretaceous (Coniacian–Maastrichtian). This sag basin is filled by a sandy siliciclastic sequence with a preserved maximum thickness of 480 m, deposited in semiarid to desert conditions. Its basement consists of volcanic rocks (mainly basalts) of the Lower Cretaceous (Hauterivian) Serra Geral basalt flows, of the Paraná-Etendeka Continental Flood Basalt Province. The sag basin was filled by an essentially siliciclastic psammitic sequence. In lithostratigraphic terms the sequence consists of the Caiuá and Bauru groups. The northern and northeastern edges of the basin provide a record of more proximal original deposits, such as associations of conglomeratic sand facies from alluvial fans, lakes, and intertwined distributary river systems. The progressive basin filling led to the burial of the basaltic substrate by extensive blanket sand sheets, associated with deposits of small dunes and small shallow lakes that retained mud (such as loess). Also in this intermediate context between the edges (more humid) and the interior (dry), wide sand sheet areas crossed by unconfined desert rivers (wadis) occurred. In the central axis of the elliptical basin a regional drainage system formed, flowing from northeast to southwest between the edges of the basin and the hot and dry inner periphery of the Caiuá desert (southwest). Life in the Bauru Basin flourished most in the areas with the greatest water availability, in which dinosaurs, crocodiles, turtles, fish, amphibians, molluscs, crustaceans, and charophyte algae lived. The fossil record mainly consists of transported bones and other skeletal fragments. In the northeastern and eastern marginal regions fossils are found in marginal alluvial fan deposits, broad plains of braided streams and ephemeral alkaline water lakes. In the basin interior the fossil record is related to deposits in sand sheets with braided streams, small dunes, and shallow lakes. In the great Caiuá inner desert a few smaller animals could survive (small reptiles and early mammals), sometimes leaving their footprints in dune foreset deposits. The aim of this article is to present and link the basin sedimentary evolution, palaeoecological features and palaeontological record.  相似文献   
942.
The Chos Malal fold and thrust belt (FTB) is a thick-skinned mountain belt formed by Mesozoic deposits of the Neuquén Basin during the Andean orogeny. Four structural cross-sections in the entire deformed area, supported by field and subsurface data, suggest a strong link between thick and thin-skinned structures. Major Andean thrusts branching from a detachment placed 12 km into the crust created large basement wedges, which were inserted in the cover producing minor order structures. The westernmost of these wedges is exposed forming the Cordillera del Viento, while others basement slices at depth were interpreted from seismic lines. These thick-skinned structures transferred deformation to the cover along the Auquilco Formation and contributed to create all thin-skinned structures surveyed in the Chos Malal FTB. We recognized half-graben geometries in the seismic lines, preserving their extensional configuration, which suggests that the main normal faults were not inverted. Shortenings calculated from the restoration of the four cross-sections are 16.9 km (29.7%), 16.9 km (29.7%), 14.7 km (26.9%) and 14.15 km (26.3%), which evidence a slight diminution of the contraction toward the south probably associated with the plunge of the Cordillera del Viento structure in this segment of the Chos Malal FTB.  相似文献   
943.
The San Jorge Gulf Basin, located in Central Patagonia, has been interpreted as a Jurassic-Cretaceous rift basin that was later inverted mainly in its western sector. Consequently, the Bernardides System formed as a set of foreland contractional structures that constitute the core of the Patagonian broken foreland, exhuming continental deposits of the Cretaceous Chubut Group, 500 km away from the Pacific trench. In spite of the intense research done in the San Jorge Gulf Basin many aspects remain under discussion, particularly those regarding the age of uplift of the Bernárdides System. In order to unravel the tectonic evolution of the western San Jorge Gulf Basin (Río Mayo Sub-Basin), we analyzed subsurface information (2D and 3D seismic lines and oil wells) located in the western area of the basin and compared this with surface data of the southern Bernárdides System. Based on our interpretation, the western part of the basin could have been uplifted in a series of deformational events that began as early as late Early Cretaceous, related to the initial uplift of the Patagonian broken foreland, during the early stages of South Atlantic opening. Subsequent stages of tectonic reactivation identified in this system have selectively inverted previous extensional structures according to the variable direction of the greatest horizontal stress (σ1) acting at each time.  相似文献   
944.
Upper Jurassic and Lower Cretaceous sedimentary layers are represented in the Brazilian Paraná Basin by the fluvio–aeolian Guará Formation and the Botucatu Formation palaeoerg, respectively, overlapped by the volcanic Serra Geral Formation. In Uruguay, the corresponding sedimentary units are named Batoví and Rivera Members (both from the Tacuarembó Formation), and the lava flows constitute the Arapey Formation (also in Paraná Basin). Despite the lack of body fossils in the mentioned Brazilian formations, Guará/Batoví dinosaur fauna is composed of theropod, ornithopod and wide–gauge sauropod tracks and isolated footprints, as well as theropod teeth. In turn, the Botucatu/Rivera dinosaur fauna is represented by theropod and ornithopod ichnofossils smaller than those from the underlying units. The analysis of these dinosaur ichnological records and comparisons with other global Mesozoic ichnofauna indicates that there is a size reduction in dinosaur fauna in the more arid Botucatu/Rivera environment, which is dominated by aeolian dunes. The absence of sauropod trackways in the Botucatu Sandstone fits with the increasingly arid conditions because it is difficult for heavy animals to walk on sandy dunes, as well as to obtain the required amount of food resources. This comparison between the Upper Jurassic and Lower Cretaceous dinosaur fauna in south Brazil and Uruguay demonstrates the influence of aridization on the size of animals occupying each habitat.  相似文献   
945.
兰坪盆地西缘发育一条重要的脉状Cu矿带,矿床的成矿流体来源一直存在较大的争议。本次研究对该矿带南段新发现的茅草坪矿床进行流体包裹体和H-O-C-S同位素研究,结合前人发表的该矿带矿床的同位素数据,探讨矿床成矿流体特征和来源。茅草坪矿床早(A1脉)、晚(A2脉)两期含矿石英脉中的流体包裹体均为含CO2盐水包裹体,可细分为含石盐子晶、富液相(水溶液相)、富气相(CO2相)包裹体等不同类型。根据流体包裹体的共生特点,将其划分为3组包裹体组合:(1)第I组,出现在A1脉石英中,为富液相(I-W型)、富气相(I-C型)和含石盐子晶(I-S型)包裹体共生;(2)第Ⅱ组,同样出现在A1脉石英中,为富液相(Ⅱ-W型)和富气相(Ⅱ-C型)包裹体共生;(3)第Ⅲ组,出现在A2脉石英中,为富液相(Ⅲ-W型)和富气相(Ⅲ-C型)包裹体共生。测温结果显示:I-S型包裹体均一温度在293~370℃之间,流体盐度为30.06%~39.76%Na Cleqv;Ⅱ-W型包裹体均一温度在302~490℃之间,流体盐度为1.23%~18.63%Na Cleqv;Ⅲ-W型包裹体均一温度在263~400℃之间,流体盐度为1.20%~11.34%Na Cleqv。同一组内,包裹体气/液相比高度变化,表明包裹体捕获时的流体呈不均一态,此时包裹体均一温度中低值部分近似代表该组包裹体真实的捕获温度。因此,从I组到Ⅲ组,包裹体分别捕获于280~320℃(I组、Ⅱ组)和260~280℃(Ⅲ组),结合盐度数据,反应初始成矿流体发生沸腾作用,伴随石盐子晶析出,流体盐度下降,随后温度降低。茅草坪矿床成矿流体富CO2的特点与区域内其他脉状Cu矿床一致,但盐度明显偏高。矿床热液石英的δDV-SMOW值变化在-94.6‰~-56.2‰之间,计算的流体的δ18OV-SMOW值集中在+8.1‰~+9.6‰之间,与区域其他脉状Cu矿床相似,数据主要落在原生岩浆水区域的下方,表明流体来源于岩浆水,但经历了开放系统下的脱气作用,没有盆地流体或大气降水的贡献;热液碳酸盐方解石的δ13CV-PDF值为-8.3‰~-2.4‰,δ18OV-SMOW值为14.46‰~16.63‰,与区域其他脉状Cu矿床的C-O同位素组成相似,但C同位素组成明显低于区域脉状Pb-Zn矿床(碳主要来自盆地流体溶解的碳酸盐岩);黄铜矿的δ34SV-CDT值变化于-6.4‰~-3.9‰之间,处于区域其他脉状Cu矿床的S同位素组成范围内,但区别于区域砂岩型Cu矿床(硫来自硫酸盐的细菌还原作用)。因此,推测矿床的CO2和硫可能也来自脱气的岩浆。茅草坪脉状Cu矿床成矿流体的研究表明:兰坪盆地西缘脉状Cu矿床成矿流体可能来自富CO2、经历脱气的岩浆水,没有大气降水和盆地卤水的参与。  相似文献   
946.
黄全海  赵尊亭  王利芳 《探矿工程》2015,42(11):66-69,79
由于施工质量问题,洛阳一个赤泥库大坝在试运行中发生大面积渗漏及管涌。在对渗漏原因进行分析的基础上实施的在坝内坡增设土工膜、坝轴线上游增设帷幕灌浆防渗墙、坝体下游坡面增设排渗沟和排水棱体等抢险加固措施,有效地解决了坝体渗漏问题。在灌浆处理过程中,针对筑坝材料的复杂性和不均匀性,通过施工前的灌浆试验,取得了适合本场地条件的钻孔施工工艺参数及灌浆方式、灌浆压力、灌浆段确定、水灰比比级等施工技术参数,确保了灌浆处理的效果。  相似文献   
947.
塔西南新生代前陆盆地东段盆山结构与冲断带变形特征   总被引:1,自引:0,他引:1  
塔西南新生代前陆盆地受西昆仑山造山带南北向挤压和帕米尔弧形构造带向北突进的影响,导致盆山结构与盆地冲断带构造变形在平行造山带方向表现出明显差异。本文通过地震资料解释,系统研究了塔西南新生代前陆盆地东段盆山结构与冲断带的构造变形特征,认为塔西南新生代前陆盆地东段盆山结构表现为西昆仑造山带向北大规模冲断,盆地区挠曲沉降,前陆地区发育宽的褶皱冲断带,冲断带前锋已扩展至捷得背斜一线,褶皱冲断带与前渊坳陷存在大范围重叠。盆地东段的褶皱冲断带在纵向上可以分为基底卷入变形带、滑脱变形带。山前第一排变形带受多期构造叠加影响,产生横向变形的分异:西段柯东段早期为构造楔形体变形形成的背斜构造,后期被甫沙–克里阳右行走滑断裂改造,剖面呈现复杂的变形特征;东段克里阳段构造变形以早期的逆冲推覆为主。结合生长地层与磁性地层分析,冲断带的变形总体表现出前展式的构造变形特征,上新世阿图什组沉积期开始形成柯东构造带;随后变形向北传播,在上新世早中期形成柯克亚构造带;至早中更新世晚期,构造变形扩展至固满–合什塔格构造带。  相似文献   
948.
孙旭东  吴冲龙  周霞  等 《江苏地质》2015,39(3):383-388
石油勘探是高风险行业,勘探地质研究业务需要复杂的逻辑思维,也需要创新性的抽象思维。“智慧油田”和“智能勘探”理论体系的提出,顺应了油气勘探的智能、快速和高效的需求。通过剖析油气勘探的信息支撑框架设计,提出了未来智能化勘探的4层设计概念,形成了层次之间的衔接和沟通的关键技术,并针对此理论体系探索了石油行业中石油地质勘探智能化信息框架实施策略。  相似文献   
949.
横山地区位于盆鄂尔多斯盆地北部,上古生界下石盒子组盒8期处于辫状河三角洲平原与三角洲前缘过渡区。由于地形平缓、间歇性水流供给使得河流频繁改道。不同形态与规模的河道砂体交错叠置,加大连续沉积砂体的寻找难度。通过连井剖面追踪主河道内的单一砂体,揭示其空间展布规律,多条砂体追踪得到不同厚度砂体的空间延伸形态,其结果表明连续沉积越厚的砂体,其延伸距离越远。基于砂泥叠置关系与砂体发育规模确定优势砂体为多期次叠加的且隔夹层较少的具有一定规模的整套砂体。优势砂体空间延伸较远、沉积厚度较大、岩性较为均一,为理想的储集砂体。确定优势砂体的平面发育情况,为优势储层的寻找奠定基础。  相似文献   
950.
淮阴—响水口断裂为江苏地层分区的重要界线,其陆域位置研究历来已久,但海域位置至今尚未明确。本次研究利用多方法手段,首次确定了淮阴-响水口断裂在南黄海海域的具体位置走向,并明确了开山岛地层归属。  相似文献   
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