Sedimentary and geochemical characterization of Middle–Late Miocene formations in the Neogene Tsugaru Basin,Japan by means of DTH27‐1 well sediment analysis     

Paolo Martizzi  Shun Chiyonobu  Hiroyuki Arato 《Island Arc》2020,29(1)

Middle–Late Miocene age siliceous formations outcropping along the northwestern side of Honshu Island are considered prospective source rocks for hydrocarbons. An analysis of geophysical, sedimentological, and geochemical properties is essential to evaluate the formations' source potential, and to understand the factors that determined the accumulation and preservation of organic matter. This study investigates the Middle–Late Miocene geological record of the Tsugaru back‐arc basin, located in the western part of Aomori prefecture, through an analysis of a 200 m long portion of a core from the DTH27‐1 well; this core is composed of the diatomaceous siltstones of the Akaishi Formation and the siliceous mudstones of the Odoji Formation. Sedimentological and geophysical characterization showed that the Akaishi Formation's diatomaceous siltstones are mostly massive and bioturbated, have low magnetic susceptibility, and demonstrate moderate natural radioactivity. Although the Odoji Formation's siliceous mudstones are massive, they have exceedingly low magnetic susceptibility and high natural radioactivity. Geochemical data from a Rock‐Eval Pyrolysis such as total organic carbon and generative potential (S1 + S2) revealed that, in the Tsugaru area, only the Odoji Formation is a likely prospective source rock for hydrocarbons. On the other hand, T_max values indicate that both the formations are thermally immature for generating hydrocarbons. The difference between the Akaishi and Odoji Formation in the sedimentological facies, in terms of the degree of bioturbation and the organic carbon content, indicates variations in lithological properties, such as porosity and grain size; moreover, this difference indicates a variation in the paleo‐oxygenation of bottom waters, with the transition from oxygen‐deficient conditions in the Middle Miocene to the more oxygenated conditions in the Late Miocene. Both the lithological and paleo‐environmental factors possibly influenced the organic richness in the two formations.  相似文献   

青海共和盆地地热流体地球化学特征及热储水-岩相互作用过程     

马月花  唐保春  苏生云  张盛生  李成英 《地学前缘》2020,27(1):123-133

地热流体地球化学组成及其运移规律和成因机制研究对地热资源勘查和开发利用具有重要意义。当前,青海省地热资源开发利用程度低,更缺乏针对地热流体地球化学特征进行深入研究的系统性工作。青海共和盆地是青藏高原北缘的一个断陷盆地,盆地内地热资源丰富。本文以共和盆地及周围部分山区的地热系统为研究对象,基于系统地球化学采样和测试开展了地热流体地球化学组成及热储水-岩相互作用过程分析,认为:从共和下更新统热储、新近系热储到鄂拉山构造岩浆带再到瓦里贡山构造岩浆带,地热水中SiO₂含量依次升高,反映热储温度依次升高;上述地热地区热储中原生铝硅酸盐矿物的溶解和蚀变矿物的形成是控制地热水中阳离子含量的最重要的水文地球化学过程,而补给水下渗和地热水径流及升流过程中盐类矿物的溶滤则是水中阴离子(特别是 {\mathrm{SO}}_4^{2-}和Cl^-)的主要来源。  相似文献   

Mesozoic–Cenozoic stress field magnitude in Sichuan Basin,China and its adjacent areas and the implication on shale gas reservoir: Determination by acoustic emission in rocks     

《China Geology》2020,3(4):591-601

The Sichuan Basin is one of the vital basins in China, boasting abundant hydrocarbon reservoirs. To clarify the intensity of the tectonic stress field of different tectonic episodes since the Mesozoic and to identify the regional dynamic background of different tectonic movements in the Sichuan Basin and its adjacent areas, the characteristics of the acoustic emission in rocks in different strata of these areas were researched in this paper. Meanwhile, the tectonic stress magnitude in these areas since the Mesozoic was restored. The laws state that the tectonic stress varied with depth was revealed, followed by the discussion of the influence of structural stress intensity on structural patterns in different tectonic episodes. These were conducted based on the paleostress measurement by acoustic emission method and the inversion principle of the stress fields in ancient periods and the present, as well as previous research achievements. The results of this paper demonstrate that the third episode of Yanshanian Movement (Yanshanian III) had the maximum activity intensity and tremendously influenced the structural pattern in the study area. The maximum horizontal principal stress of Yanshanian III varied with depth as follows: 0.0168 x + 37.001 (MPa), R² = 0.8891. The regional structural fractures were mainly formed in Yanshanian III in Xujiahe Formation, west Sichuan Basin, of which the maximum paleoprincipal stress ranging from 85.1 MPa to 120.1 MPa. In addition, the law stating the present maximum horizontal principal stress varies with depth was determined to be 0.0159 x+10.221 (MPa), R²=0.7868 in Wuling Mountain area. Meanwhile, it was determined to be 0.0221 x+9.4733 (MPa), R²=0.9121 in the western part of Xuefeng Mountain area and 0.0174 x+10.247 (MPa), R²=0.8064 in the whole study area. These research results will not only provide data for the simulation of stress field, the evaluation of deformation degree, and the prediction of structural fractures, but also offer absolute geological scientific bases for the elevation of favorable shale gas preservation.  相似文献   

Paleogene evolution and demise of the proto‐Paratethys Sea in Central Asia (Tarim and Tajik basins): Role of intensified tectonic activity at ca. 41 Ma     

Mustafa Y. Kaya  Guillaume Dupont‐Nivet  Jean‐Noël Proust  Pierrick Roperch  Laurie Bougeois  Niels Meijer  Joost Frieling  Chiara Fioroni  Sevin zkan Alt&#x;ner  Ezgi Vardar  Natasha Barbolini  Marius Stoica  Jovid Aminov  Mehmut Mamtimin  Guo Zhaojie 《Basin Research》2019,31(3):461-486

The proto‐Paratethys Sea covered a vast area extending from the Mediterranean Tethys to the Tarim Basin in western China during Cretaceous and early Paleogene. Climate modelling and proxy studies suggest that Asian aridification has been governed by westerly moisture modulated by fluctuations of the proto‐Paratethys Sea. Transgressive and regressive episodes of the proto‐Paratethys Sea have been previously recognized but their timing, extent and depositional environments remain poorly constrained. This hampers understanding of their driving mechanisms (tectonic and/or eustatic) and their contribution to Asian aridification. Here, we present a new chronostratigraphic framework based on biostratigraphy and magnetostratigraphy as well as a detailed palaeoenvironmental analysis for the Paleogene proto‐Paratethys Sea incursions in the Tajik and Tarim basins. This enables us to identify the major drivers of marine fluctuations and their potential consequences on Asian aridification. A major regional restriction event, marked by the exceptionally thick (≤ 400 m) shelf evaporites is assigned a Danian‐Selandian age (ca. 63–59 Ma) in the Aertashi Formation. This is followed by the largest recorded proto‐Paratethys Sea incursion with a transgression estimated as early Thanetian (ca. 59–57 Ma) and a regression within the Ypresian (ca. 53–52 Ma), both within the Qimugen Formation. The transgression of the next incursion in the Kalatar and Wulagen formations is now constrained as early Lutetian (ca. 47–46 Ma), whereas its regression in the Bashibulake Formation is constrained as late Lutetian (ca. 41 Ma) and is associated with a drastic increase in both tectonic subsidence and basin infilling. The age of the final and least pronounced sea incursion restricted to the westernmost margin of the Tarim Basin is assigned as Bartonian–Priabonian (ca. 39.7–36.7 Ma). We interpret the long‐term westward retreat of the proto‐Paratethys Sea starting at ca. 41 Ma to be associated with far‐field tectonic effects of the Indo‐Asia collision and Pamir/Tibetan plateau uplift. Short‐term eustatic sea level transgressions are superimposed on this long‐term regression and seem coeval with the transgression events in the other northern Peri‐Tethyan sedimentary provinces for the 1st and 2nd sea incursions. However, the 3rd sea incursion is interpreted as related to tectonism. The transgressive and regressive intervals of the proto‐Paratethys Sea correlate well with the reported humid and arid phases, respectively in the Qaidam and Xining basins, thus demonstrating the role of the proto‐Paratethys Sea as an important moisture source for the Asian interior and its regression as a contributor to Asian aridification.  相似文献   

张掖盆地地下水硝酸盐污染与人体健康风险评价     

盛丹睿  温小虎  冯起  武君  司建华  吴敏 《中国沙漠》2019,39(5):37-44

地下水是张掖盆地的重要水资源，其硝酸盐污染尚未得到足够重视。对张掖盆地2004、2015年地下水硝酸盐浓度进行了系统分析，并采用美国环境保护署（USEPA）推荐的健康风险评价模型评估了地下水硝酸盐的健康风险。结果表明：自2004年以来张掖盆地地下水硝酸盐污染日趋严重。2015年硝酸盐浓度最高已达到283.32 mg·L^-1，17.61%的采样点硝酸盐氮浓度超过GB5749-2006《生活饮用水卫生标准》中饮用地下水限量值（20 mg·L^-1）。研究区人群经皮肤接触途径摄入硝酸盐的健康风险在可接受水平，而饮水摄入硝酸盐的健康风险较高，总风险中饮水途径引起健康风险的贡献率占99.40%，远大于皮肤接触途径。儿童经饮水摄入和皮肤接触两种途径的健康风险均显著高于成人，分别为成人的1.544倍和1.039倍。32.39%的采样点地下水硝酸盐对儿童的健康风险超出了可接受水平，14.79%的采样点地下水硝酸盐对成人的健康风险不可接受。甘州区城区、临泽县北部边缘及高台县城区周围硝酸盐浓度最高，这些区域内所有人群都面临硝酸盐引发的高健康风险，其余区域硝酸盐引发的健康风险相对较低。  相似文献   

Tectono-sedimentary evolution of Jurassic–Cretaceous diapiric structures: Miravete anticline,Maestrat Basin,Spain     

Jaume Vergés  Yohann Poprawski  Ylènia Almar  Peter A. Drzewiecki  Mar Moragas  Telm Bover-Arnal  Chiara Macchiavelli  Wayne Wright  Grégoire Messager  Jean-Christophe Embry  David Hunt 《Basin Research》2020,32(6):1653-1684

Integration of extensive fieldwork, remote sensing mapping and 3D models from high-quality drone photographs relates tectonics and sedimentation to define the Jurassic–early Albian diapiric evolution of the N–S Miravete anticline, the NW-SE Castel de Cabra anticline and the NW-SE Cañada Vellida ridge in the Maestrat Basin (Iberian Ranges, Spain). The pre shortening diapiric structures are defined by well-exposed and unambiguous halokinetic geometries such as hooks and flaps, salt walls and collapse normal faults. These were developed on Triassic salt-bearing deposits, previously misinterpreted because they were hidden and overprinted by the Alpine shortening. The Miravete anticline grew during the Jurassic and Early Cretaceous and was rejuvenated during Cenozoic shortening. Its evolution is separated into four halokinetic stages, including the latest Alpine compression. Regionally, the well-exposed Castel de Cabra salt anticline and Cañada Vellida salt wall confirm the widespread Jurassic and Early Cretaceous diapiric evolution of the Maestrat Basin. The NE flank of the Cañada Vellida salt wall is characterized by hook patterns and by a 500-m-long thin Upper Jurassic carbonates defining an upturned flap, inferred as the roof of the salt wall before NE-directed salt extrusion. A regional E-W cross section through the Ababuj, Miravete and Cañada-Benatanduz anticlines shows typical geometries of salt-related rift basins, partly decoupled from basement faults. These structures could form a broader diapiric region still to be investigated. In this section, the Camarillas and Fortanete minibasins displayed well-developed bowl geometries at the onset of shortening. The most active period of diapiric growth in the Maestrat Basin occurred during the Early Cretaceous, which is also recorded in the Eastern Betics, Asturias and Basque-Cantabrian basins. This period coincides with the peak of eastward drift of the Iberian microplate, with speeds of 20 mm/year. The transtensional regime is interpreted to have played a role in diapiric development.  相似文献   

准噶尔盆地玛湖凹陷西斜坡三叠系百口泉组扇三角洲优质储集层预测          下载免费PDF全文

桑林翔  刘军  王贵文  王苏天  李全  张云龙 《古地理学报》2020,22(6):1053-1064

针对准噶尔盆地玛湖凹陷西斜坡风南地区三叠系百口泉组扇三角洲砂岩物性空间变化大、优质储集层(孔隙度大于7.4%,渗透率大于0.05×10^-3μm²)预测难的问题,在沉积岩石学、地震沉积学以及地震反演和解释理论指导下,综合利用测井、岩心和三维地震等资料开展了高精度层序地层划分、沉积微相描述和优质储集层地震反演研究。建立了风南井区四级层序地层格架,明确了扇三角洲多期水进水退的充填过程,指出SSQ3和SSQ5是优质储集层的发育层系;识别出扇三角洲平原分流河道、河道间和扇三角洲前缘水下分流水道、河口坝、席状砂等沉积微相,指出扇三角洲平原是优质储集层发育相带;通过应用高分辨层序地层纵向边界和沉积相横向边界约束,进行分层相控叠后地震波阻抗反演,提升储集层预测精度,在SSQ3和SSQ5预测5个优质储集层发育区,提出3口井的井位建议,钻探均获工业油流。  相似文献   

Nanpanjiang basin: A window on the tectonic development of south China during Triassic assembly of the southeastern and eastern Asia     

《Gondwana Research》2020

As the largest siliciclastic sink in the South China block, the Triassic Nanpanjiang basin is generally thought of as a foreland basin related to Indosinian collision between the South China and Indochina blocks. Our basin analysis, spanning an eight years period, provides details of Lopingian to Middle Triassic stratigraphic fill and tectonic subsidence of the basin. Field observation and sedimentological analyses reveal that the basin was not filled by a monotonous turbidite system and suggest instead the development of five primary depositional units constituted by deep-water turbidite systems, mass-transport deposits, condensed drapes, shallow-water isolated carbonate platforms, and volcano-volcaniclastic rocks. The stratigraphic completeness of the basin, the coexistence of widespread but localized carbonate platforms within axially filled deep-water basin, tectonically generated cyclothems of transverse mass-transport deposits along intrabasinal faults and basin fill of extrusive rocks of bimodal composition together apparently call in question the claim that crustal shortening prevailed during the Late Permian to pre-Norian Triassic. Patterns of basin fill, differential tectonic subsidence and very high subsidence rate of the region adjacent to master fault are more closely match the pattern expected for extensional to transtensional basin in a back-arc setting. The crustal extension in the southwestern South China was not consistent with hypothesized Indosinian collision between South China and Indochina blocks, but more likely developed in response to northwestward subduction of the paleo-Pacific plate. Our results, combined with regional considerations, lead to a new model for the Triassic tectonic evolution of South China during Triassic assembly of the southeastern and eastern Asia.  相似文献   

华南上扬子区深部温度估算及其油气地质意义     

李香兰  刘绍文  徐明  李旭东  郝春艳 《地质学报》2020,94(6):1896-1910

盆地热体制及深部温度估算对油气和区域地热能资源评估具有重要意义。南方上扬子区是海相油气勘探的重要区块,近年来更是我国页岩气勘探的主要选区。然而,由于数据不足及研究目标的分散,该区的盆地热体制特征还有待深化。结合前人已有地热数据,并整合新近开展的稳态测温数据,我们揭示了上扬子区现今地温梯度、大地热流分布特征,继而估算了1000～6000m埋深处的深部地层温度和2套主要古生界海相烃源岩底界面处的温度。结果表明,上扬子区具有中-低温的地热状态,其现今地温梯度和大地热流的范围(平均值)分别为10～74℃/km(24℃/km)和27～118mW/m~2(64mW/m~2),整体上从东北向西南方向递增,呈现出"东北低、西南高"的分布趋势。1000～6000m埋深处估算温度的分布格局与地温梯度及热流的分布趋势基本一致。东北部的鄂西-湘北地区为低温区,中部的四川盆地其大部分为中温区,西南的云南地区为高温区。上扬子区现今地热分布格局受区域差异构造和岩浆作用控制。结合储层温度估算并综合其他油气地质资料,提出川东的石柱-涪陵、川南的威远-自贡-泸州和宜宾-长宁等区的下志留统龙马溪组页岩层系是上扬子区油气勘探有利区带。  相似文献   

基于深度域地震成像的中沙海槽盆地东北部结构构造研究     

赵斌  高红芳  张衡  李丽青 《热带海洋学报》2019,38(2):95-102

文章基于叠前深度偏移地震成像分析, 结合前人重磁反演等地球物理资料成果, 对中沙海槽盆地东北部结构构造进行探索研究。研究表明: 中沙海槽盆地东北部发育新生代地层, 厚度在1500~2500m之间, 地层层速度为1500~ 3500m·s^-1, 不存在中生界沉积层, 盆地基底为海山或前寒武系基岩及岩浆岩隆起。中沙海槽盆地新生代陆源海相烃源岩丰富, 盆地新生界地层厚度大, 盆地凹陷、断裂发育, 具有一定的油气勘探潜力。  相似文献