吉林省东部的大地构造环境与构造演化轮廓

本文运用活动论思维,根据东亚构造发展的宏观背景重新认识吉林省东部地区的大地构造环境与构造演化史。阐明吉林省东部在不同时期所处大地构造环境的变化及由此所决定的不同构造阶段所表现的不同构造属性与特征,为中、新生代以来该区所发生的岩浆活动、变质作用及成矿作用提供时空背景。 本文强调了中生代以来巨大的构造改造对于塑造现今裸露地表的综合地质体面貌的重要意义。忽视它的影响就有可能把许多原本是中、新生代构造运动的产物误认为是前寒武纪就有的古构造,把复杂问题简单化,甚至导致谬误的结论。     

Risk evaluation of dam-break environmental impacts based on the set pair analysis and cloud model

Natural Hazards - Many dams have been constructed around the world. Compared with the potential losses of life and economy, the environmental impacts caused by dam breach were less analyzed. As a...     

高分辨湖泊沉积和孢粉记录对气候、水文变化的响应

通过对长江中游网湖钻孔高精度分层样品(1.5年/样品)的沉积学和孢粉学研究,试图揭示过去百年网湖在由开放到封闭体系变化中,沉积孢粉与气候、水文动力变化的过程及其相互关系.相关分析和低频滤波分析,反映出沉积物和孢粉的变化对流域降水和长江流量的敏感响应.在过去130年中的多雨洪水年份,湖泊受长江倒灌影响,沉积物以黏土细颗粒...     

Geomorphological and sedimentological comparison of fluvial terraces and karst caves in Zhangjiajie,northwest Hunan,China: an archive of sandstone landform development

The Zhangjiajie Sandstone Peak Forest Geopark (Zhangjiajie World Geopark) of northwest Hunan, China hosts a well-preserved sequence of fluvial terraces and karst caves. In this contribution, a comparative study of fluvial terraces with karst caves along the middle-lower Suoxi River in Zhangjiajie World Geopark is presented to improve the understanding of the development of striking sandstone landscape in the upper Suoxi River. By integrating geomorphological, sedimentological, and geochronological techniques, the possible correlation between fluvial terraces and karst caves, as well as their climatic and tectonic implications is investigated. The available electron spin resonance and thermo-luminescence numerical ages coupled with morphostratigraphic analysis indicate that aggradation of fluvial terrace levels occurred at ca. 347 ± 34 ka (T₄), 104.45 ± 8.88 to 117.62 ± 9.99 ka (T₃), 60.95 ± 5.18 ka (T₂), and Holocene (T₁), followed by the stream incision. Fluvial terrace levels (T₄ to T₁) correlate morphologically with the karst cave levels (L₁ to L₄), yet the proposed chronology for the fluvial terrace levels is a bit later than the chronological data obtained from karst caves. In northwest Hunan, where a unique sandstone peak forest landscape was extensively developed, the fluvial terrace sequences as well as the cave systems are the important archives for studying the evolution of the sandstone landscape. The beginning of the sandstone landscape development must be earlier than the aggradation of the fluvial terrace T₄, allowing this unique landscape to occur in the Middle Pleistocene.     

Biomarkers in the Molar Tooth （MT）-Bearing Limestones in the Jilin-Liaoning Area of China

The origin of Molar Tooth (MT) carbonates has been argued for more than 100 years, which are a kind of Proterozoic carbonates especially composed of microsparite with ptygmatically folded and sheet-like structures. Biomarkers detected in the microcalcsparite from the Wanlong and Xingmincun formations in the Jilin-Liaoning area showed there are abundant normal alkanes, isoprenoids, hopanes, steranes, alkylmethylcyclohexanes, and alkyleyclohexanes, indicating a diversity of biological source: long-chain isoprenoids, the major components of chlorophyll, such as C19, C20, a kind of major biomarkers synthesized early by isoprenoid monomers; hopanes a type of characteristic biomarkers from prokaryote, such as archaebacteria and cyanobacteria; sterane a biomarker for eukaryote; and two kinds of alkanes with C17, C18 as the main peaks representing aquatic bacteria and with C23, C24 as the main peaks representing fungi, respectively. Biomarker analysis showed that MT is the result of bacterial and algal activities, which is a kind of organisms between aerobic and anaerobic bacteria, reproducing well in normal or slightly saline sea water under weak oxidation-reduction conditions, resulting in rapid deposition of calcite as microsparite clue to some mechanisms.     

神农架大九湖泥炭地甲烷代谢菌的垂直分布与生态网络

为了探讨产甲烷菌和甲烷氧化菌群落随土壤深度的垂直分布特征及甲烷代谢菌对环境的响应机制,于2019年4个季度采集大九湖泥炭地0 cm、10 cm、30 cm和50 cm的土壤样品.通过功能基因高通量测序获得产甲烷菌和甲烷氧化菌群落结构组成并构建分子生态网络.产甲烷菌和甲烷氧化菌的最大优势属分别为Methanoregula和Methylocapsa;产甲烷菌和甲烷氧化菌群落生态网络结构及其共现模式随深度发生变化,产甲烷菌和甲烷氧化菌群落结构随深度呈相反的变化趋势;产甲烷菌和甲烷氧化菌网络中关键物种分别有3个和4个,分别为Methanoregula、Methanocella、Methanobacterium和Methylocapsa、Candidatus Methyloumidiphilus、Methylocystis、Candidatus Methylospira.表明环境因子土壤总碳、总氮、铵态氮和亚硝态氮含量等环境因子通过影响产甲烷菌和甲烷氧化菌群落进而改变CH4排放.     

物候模型在气候定量重建中的应用

利用历史物候记录重建的气候变化过程为人类更准确地认识过去的气候变化特征, 识别气候变化阶段提供了帮助。本文系统总结了现有用于气候定量重建的植物物候模型, 包括统计模型和过程模型两类。统计模型不考虑植物生理生态过程, 主要是利用物候期与气象因子之间的统计关系建立回归方程; 过程模型是一种半机理性模型, 通过植物每日发育进度与环境因子的关系, 利用数学模型模拟植物的生长过程, 主要包括春季积温 (spring warming, 简称SW)模型、温度变换日数(the number of days transformed to standard temperature, 简称DTS)模型和葡萄收获日期模型等。同时, 详细介绍了上述物候模型在国内外不同地区定量重建气候中的应用, 比较了重建的效果, 总结了重建过程的不确定性; 并提出了利用植物物候模型对气候定量重建中的关键问题, 即指出在未来研究中需要更多关注如何定量重建温度外的气候因子, 同时要加强对秋季物候的观测以及秋季物候生理机制的研究, 以便更清晰阐述秋季物候变化过程, 在历史气候变化定量重建中更充分利用有关秋季资料。     

超深层古油藏的定量表征及其对气藏形成的指示意义: 以川中古隆起北斜坡灯影组为例

跨越多个构造期的深层、超深层油气成藏定量表征是地学界的一大难题. 川中地区上震旦统灯影组天然气藏以典型的原油裂解气为主,油气演化经历了古油藏、古气藏直至现今气藏的复杂演化过程;古油藏的定量刻画是恢复其成藏过程的关键和核心. 优选川中古隆起北斜坡上震旦统灯影组气藏为研究对象,以固体沥青为媒介,在岩心观察的基础上,综合“点”（固体沥青图像法定量表征）、“线”（固体沥青多矿物测井反演定量评价）、“面”（固体沥青含量平面分布定量表征）3个维度对固体沥青进行定量刻画,进而定量刻画古油藏并以体积法计算其资源量,以期从成藏角度对斜坡区的天然气勘探潜力评价提供支撑.研究结果表明：（1）灯影组储层固体沥青主要以半充填-充填的状态赋存于孔隙空间中;灯二段固体沥青含量整体要高于灯四段;不论灯二段还是灯四段,上亚段固体沥青含量略高于下亚段;（2）固体沥青纵向和平面分布规律指示,纵向上,油气充注方向多为自上而下;平面上,油气充注主要存在两个方向：自德阳-安岳裂陷槽向台内侧向充注;自北部斜坡区向南、向古隆起高部位侧向充注;（3）北斜坡地区灯影组储层古油藏完成裂解的时间早于大规模区域构造运动,因此可以用现今储层固体沥青的含量及分布来定量刻画古油藏. 古油藏的识别标准为：固体沥青在孔隙空间充填度大于25%且固体沥青含量大于2%;（4）基于斜坡区丘滩体分布,定量刻画了川中古隆起北斜坡地区5个可靠古油藏、4个潜在古油藏,借助体积法评价所得古油藏规模约177.25×108 t,完全裂解可产生原油裂解气约109 893.94×108 m3.     

川西前陆盆地蓬莱镇组层序、岩相古地理特征及演化

在川西前陆盆地蓬莱镇组层序特征研究基础上,将川西前陆盆地蓬莱镇组划分为5个沉积层序,每个沉积层序都由进积和退积体系域组成。以体系域为编图单元,采用体系域压缩法,编制了川西前陆盆地上侏罗统蓬莱镇组9张层序岩相古地理图。编图表明,川西前陆盆地蓬莱镇期古地理演化总体上显示盆扩/盆缩的特点,并具有明显的继承性、不均一性、阶段性和同步性。与传统的岩相古地理图相比,层序岩相古地理图具有动态、精确、等时、成因连续和勘探实用等优点。     

莱州湾海洋沉积物粒度特征及其环境响应分析

基于20个柱状样粒度信息,文章对山东莱州湾海域1~3 m厚度的沉积环境展开了研究。莱州湾海域沉积物粒度组分以砂质和粉砂质为主,整体上分选性偏差,在沉积过程中受周边环境改造明显。莱州湾海洋沉积动力环境在粒度方面有较好的响应,柱状样粒度分布图反映不同海域沉积物所处的外力作用阶段各有不同,但总体上随着搬运距离增大,至中部浅海平原,概率累积曲线斜率逐渐变大,阶段分化愈发明显。莱州湾浅部海域共同环境敏感组分为3≤φ≤4,沿岸河流性质和泥沙输运路径对粒度组分影响明显。综合前人关于沉积速率的研究成果,表明莱州湾东部海域粒度组分阶段性变化与1855年黄河改道在时间上存在一定的对应关系。就沉积物形成环境而言,莱州湾中部海域沉积环境水动力较强,物质来源多样。屺坶岛—刁龙嘴海域沉积物的颗粒略粗,需要的临界起动速度较大,发生再悬浮的几率相对较小。黄河水下三角洲沉积环境比较动荡,能量不稳定,处于重力流后期,能量衰减并向牵引流转化。南部的水下岸坡在波浪、潮流作用下有一定量的泥沙淤积。