蜀南地区下三叠统飞仙关组沉积相

蜀南地区飞仙关组的沉积相类型主要有浑水陆棚相与清水陆棚相,东部两者交替发育,中西部则主要为浑水陆棚相。浑水陆棚相以半局限海亚相为主,包括三个微相;清水陆棚相可分为颗粒滩、滩间、潮坪和内缘斜坡等四个亚相,包括若干微相。飞一段全区为清水陆棚相;飞二段全区均为浑水陆棚亚相的泥质半局限海微相;飞三段,西部为浑水陆棚相,东部为清水陆棚相,其间发育灰泥质半局限海微相;飞四段基本为泥质半局限海微相。飞一时,区内中部有一近南北向的台内凹槽,沿凹槽边缘鲕粒滩较发育。研究区以西的康滇古陆和龙门山岛链与华蓥山断裂带控制着区内沉积相展布,当康滇古陆和龙门山岛链构造活跃时全区发育浑水陆棚,华蓥山断裂带活动时东部发育清水陆棚;当康滇古陆、龙门山岛链与华蓥山断裂带构造的活动性都较低时,全区以清水陆棚为主。     

川东北地区不同构造带地层水化学特征与油气保存的关系

判断油气藏保存条件的优劣,除了盖层和断层封闭性之外,还有油气水的化学特征,如地层水的交替或油气散失。通过对川东北地区地层水的水型、矿化度、水性系数等参数的综合分析认为,川东北宣汉—达县地区与通江—南江—巴中地区的地层水具有矿化度高和氯镁系数越大,变质系数、脱硫系数和碳酸盐平衡系数就越小的特点。矿化度、水性系数及水型的变化具有很好的一致性,表明该区存在有利于油气保存的水文地质条件。     

云南楚雄盆地上三叠统沉积及地球化学的海相特征

楚雄盆地为中生代形成的典型前陆盆地。三叠纪是其形成的主体阶段和盆山转换的重要时期,也是由海相向陆相沉积环境的转折期,同时上三叠统是楚雄盆地最重要的油气资源层系。通过对楚雄盆地上三叠统进行系统的沉积学、层序地层学和波动地质学分析,在上三叠统识别出3个三级层序,建立了层序地层格架和高频波动曲线。对层序地层格架内的碳、氧同位素和微量元素的特征进行分析,发现楚雄盆地晚三叠世诺利晚期—瑞替期沉积具有海相沉积环境的地球化学特征,同时综合多学科的研究成果,指出楚雄盆地该时期为一与海域相接的近海湖盆,并受到间歇性海侵的影响。而海相烃源岩与陆相烃源岩在生烃能力、分布规律等方面均具有较大的差异。因此,这一认识对于重新评价楚雄盆地晚三叠世烃源岩具有重要意义。     

关于创口海百合(Traumatocrinus)的分类、分布及古生态

在中国贵州关岭地区晚三叠世(卡尼期)小凹组(=瓦窑组)海生爬行动物和海百合化石库中产有大量完好保存的创口海百合(Traumatocrinus)(棘皮动物门,海百合纲)化石。根据对此类海百合分类、分布和形态构造及古生态的研究,特别是大量完好保存、且附着在漂浮木头上的群体化石标本的发现,进一步证明这种外形似海百合花的创口海百合营假浮游的生活方式。这类特化的海百合分枝起源于另一类底栖中三叠世石莲海百合科,很快占领了卡尼期初期的生态境,至卡尼期末创口海百合衰退以后,它的生态境在诺利期时为形态发生的趋同变异的链海百合(Seirocrinus)和五角海百合(Pentacrinites)所占领。     

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

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.     

Distribution of diagenetic alterations within depositional facies and sequence stratigraphic framework of fluvial sandstones: Evidence from the Petrohan Terrigenous Group,Lower Triassic,NW Bulgaria

Sequence stratigraphy of fluvial deposits is a controversial topic because changes in relative sea level will eventually have indirect impact on the spatial and temporal distribution of depositional facies. Changes in the relative sea level may influence the accommodation space in fluvial plains, and hence have impact on types of fluvial system, frequency of avulsion, and style of vertical and lateral accretion. This study aims to investigate whether depositional facies and changes in the fluvial system of the Lower Triassic Petrohan Terrigenous Group sandstones (NW Bulgaria) in response to changes in the relative sea level have an impact on the spatial and temporal distribution of diagenetic alterations.     

Gas generation and expulsion characteristics of Middle–Upper Triassic source rocks,eastern Kuqa Depression,Tarim Basin,China: implications for shale gas resource potential

Frontier exploration in the Kuqa Depression, western China, has identified the continuous tight-sand gas accumulation in the Lower Cretaceous and Lower Jurassic as a major unconventional gas pool. However, assessment of the shale gas resource in the Kuqa Depression is new. The shale succession in the Middle–Upper Triassic comprises the Taliqike Formation (T₃t), the Huangshanjie Formation (T₃h) and the middle–upper Karamay Formation (T_2–3k), with an average accumulated thickness of 260 m. The high-quality shale is dominated by type III kerogen with high maturity and an average original total organic carbon (TOC) of about 2.68 wt%. An improved hydrocarbon generation and expulsion model was applied to this self-contained source–reservoir system to reveal the gas generation and expulsion (intensity, efficiency and volume) characteristics of Middle–Upper Triassic source rocks. The maximum volume of shale gas in the source rocks was obtained by determining the difference between generation and expulsion volumes. The results indicate that source rocks reached the hydrocarbon expulsion threshold of 1.1% VR and the hydrocarbon generation and expulsion reached their peak at 1.0% VR and 1.28% VR, with the maximum rate of 56 mg HC/0.1% TOC and 62.8 mg HC/0.1% TOC, respectively. The volumes of gas generation and expulsion from Middle–Upper Triassic source rocks were 12.02 × 10¹² m³ and 5.98 × 10¹² m³, respectively, with the residual volume of 6.04 × 10¹² m³, giving an average gas expulsion efficiency of 44.38% and retention efficiency of 55.62%. Based on the gas generation and expulsion characteristics, the predicted shale gas potential volume is 6.04 × 10¹² m³, indicating a significant shale gas resource in the Middle–Upper Triassic in the eastern Kuqa Depression.     

黔南桂北下三叠统碳酸盐海岸—陆架沉积总体的沉积构成及沉积过程分析

在黔南桂北下三叠统进行沉积过程和沉积构成分析的基础上,识别出了构成碳酸盐海岸—陆架沉积总体的4种成因单位和7种沉积相。同时本文还对碳酸盐海岸—陆架沉积总体的演化过程及其与其它沉积总体的空间组合关系进行了讨论。     

新疆昆仑山乌斯腾塔格—喀拉米兰晚三叠世植物化石的首次发现

新疆昆仑山乌斯腾塔格—喀拉米兰地区晚三叠世植物群Drepanozamites nilssoni-Otozamites indosinensis-Thinnfeldia nordenskioldi-Glossophyllum sheisense等的首次发现,揭示了该地区中国南方型晚三叠世植物群的面貌.对研究新疆南部地区晚三叠世地层、中国地层区划及晚三叠世植物群地理分区、以及板块构造等均具有重要意义.