Holocene carbon storage and testate amoeba community structure in treed peatlands of the western Hudson Bay Lowlands margin,Canada

The Hudson Bay Lowlands (HBL) stores a significant proportion of the northern peatland carbon pool, and constraints on the factors controlling local-scale variation are needed to better predict soil carbon stocks. We investigated two treed peatland sites, a fen and a bog, to understand how local ecohydrological factors impacted long-term carbon storage. Ecohydrological conditions were reconstructed using quantitative water table depth reconstructions from testate amoebae (TA) and broad peat type classifications. We also linked these factors and carbon storage to changes in TA community structure through the investigation of morphological and functional traits. Both sites have high rates of peat vertical accretion during the warmer Middle Holocene. A shift to a drier, Sphagnum-dominated habitat after 7400 cal a bp at the bog site, however, led to lower apparent carbon accumulation rates (aCARs) than at the fen site. aCARs decreased with the transition to a cooler Late Holocene climate at both sites. Both sites have higher total carbon masses (kg m⁻²) than other more open and younger HBL localities, demonstrating the potential importance of treed peatlands in regional carbon storage. Shifts in the frequency of TA traits corresponded to changing ecohydrological conditions and provided insights into the role of TA in carbon storage.     

The preservation potential of microstructures during static grain growth

Grain growth simulations using the microstructure simulation system Elle have been performed in materials with a pre‐existing grain shape foliation. As might be expected, the foliation is destroyed by the end of the experiment, and grain areas have increased by a factor of seven. The area of material swept by the migrating grain boundaries was monitored, and it was found that at every stage, virtually all of the grains which survived the grain growth process contain one and only one core of ‘unswept’ material. Remarkably these remnant unswept cores preserve a useable record of the initial grain size and the orientation of the grain shape foliation. This work suggests that, even for samples where no equivalent protolith can be found, it may be possible to see past a grain growth episode to estimate the original grain shape and grain size of the rock, and perhaps even reconstruct the grain boundary kinematics. In addition the identification of unswept cores has the potential to help unravel the evolution of grain boundary chemistry in rocks during metamorphism. As an example of a natural system showing these microstructures, we describe a peridotite from Almklovdalen, Norway. This peridotite was infiltrated by aqueous fluids at several stages during late Caledonian exhumation and retrogressive metamorphism. Grain boundary migration associated with the last of these infiltration events swept off abundant intragranular fluid inclusions in the original chlorite‐peridotite. At the grain scale, microstructural mapping of the fluid inclusion rich areas shows that, as with the numerical simulations, many of the grains retain exactly one core of unswept material. Examples of other natural systems discussed include dislocation density distributions and trace element zoning.     

新民堡断裂新构造活动特征

新民堡断裂属于河西走廊西段酒西盆地内断裂系的组成部分,位于嘉峪关以西40km的新民堡一带。新民堡断裂呈北西西向延伸,长8.0km,走向299°,倾向南西,倾角20°～35°。断裂下部主要发育在新近系红色泥岩中,地表穿切上更新统和全新统,变形性质以蠕滑变形为主,活动方式属于逆冲推覆;新民堡断裂在距今69.3ka与35.4ka之间、距今28.3ka左右,距今4.4ka左右发生过新构造活动。断裂位移速率为0.54～0.90mm/a,其中垂直位移速率为0.26～0.50mm/a。同时,以新民堡断裂为代表的低角度逆冲推覆断裂是造成酒西盆地及河西走廊横向压缩的重要因素和表现形式之一。     

广东大亚湾海洋地质环境与潜在地质灾害

大亚湾是国家重点开发的海湾，通过对其大量实测资料的综合分析和研究表明，大亚湾有9种底质类型，除沿岸及岛屿周围颗粒较粗外，湾内浅海区主要为粘土质粉砂和粉砂质粘土，工程地质条件较好。大亚湾目前底质总体污染较小，以轻微污染为主，但湾内水体交换能力差，污染易而治理难，应倍加保护。大亚湾潜在地质灾害包括活动性地质灾害因素和限制性地质条件，主要有海岸侵蚀、沙波、断层、不规则埋藏基岩、埋藏脊、航道沟、异常堆积区和陡坎等。     

塔拉斯-费尔干纳断裂带南端构造转换及其新生代区域构造响应

塔拉斯费尔干纳断裂(TF)为中亚最大规模的断裂,其向南是否贯穿塔里木盆地西部研究较少,带来对其新生代运动性质的争论。研究表明,TF断裂在喀什凹陷以小规模的右旋走滑断裂逐渐消失,断层东盘以逆冲断层系的水平缩短变形,调节新生代右旋走滑位移,与巴楚隆起的阻挡作用相关。区域构造分析表明,随着帕米尔北缘逆冲断层系向北扩展,喀什凹陷中新生代沉积形成密集分布的线性褶皱和逆冲断层带。帕米尔高原向北仰冲触发TF不同区段在新生代差异性构造复活,发生大规模右旋位移及其南端构造转换(逆冲带隆升和前陆盆地发育)。新生代大断裂差异性复活及其构造调节,造成帕米尔构造节东西两侧不对称的构造样式。     

新疆查汗萨拉锑矿床地球化学特征

新疆查汗萨拉锑矿床位于西南天山中部的萨阿尔明晚古生代沟弧带的西段,它与萨瓦亚尔顿金锑银矿、卡拉脚古牙锑金矿、古勒克达坂卡堤锑金矿等构成查汗萨拉锑金矿带。矿区总体受控于一大型逆冲推覆构造带,处于查汗萨拉锑异常区浓集中心域内。矿体产于下泥盆统阿尔腾克斯组含炭碎屑岩中,显示多元素多阶段成矿特征。成矿物质来自于赋矿地层,成矿热液则是由岩浆水和天水组成的混合水,属沉积改造型锑银多金属矿床。     

金顶铅锌矿床穹隆构造成及其相关问题探讨

依据大量地质事实，本文论述了滇西兰坪盆地古新世自东向西的滑覆，始新世末期自西向东的推覆，首次提出了金顶穹隆构造成生于两期背斜的横跨式叠加的观点，并论述了穹隆构造的控矿作用。     

Response of landfill clay liners to extended periods of freezing

This paper presents the results of a physical model study of the performance of landfill clay cover liners subjected to extended freezing periods. Three proposed designs for a prototype cover liner were evaluated with a primary objective being the determination of frost penetration resulting from the sub-freezing temperatures imposed as an upper boundary condition to the model. The ultimate performance of the three liner designs were compared on the basis of frost penetration, leakage through the liner, and frost heave. The observed depth of frost penetration was compared to that predicted using a simplified analytical solution of the thermodynamic problem, in addition to measured field behavior.

The laboratory experiment utilizes a 1.8 m² tank, of ca 2.1 m depth. The tank is loaded with clay to the specifications required for landfill liners. Three different landfill cover liner designs were modeled in the experimental tank. The performance of the three designs, as measured by a variety of observations, were compared. Frost heave was measured for each design and was found to vary between 3.8 and 4.3 cm. The results indicate the depth of frost penetration was similar for all designs tested (29.2–31.7 cm), although the design which included a soil drainage layer had superior leakage performance.     

塔里木盆地哈得逊油田断裂特征与油气运移

通过断裂分析及构造演化,并结合油气地化指标,综合研究认为,哈得逊油气的总体运移特征为“多期充注,晚期成藏”,即有垂向又有横向。海西末期-喜山期主干断层继承性活动,形成断穿石炭系底部的复活断层及伴生断层,沟通寒武系、奥陶系油源。晚加里东期、晚海西期来自寒武-奥陶系的油气沿羊屋2 井区深大断裂纵向运移,哈得逊石炭系整体南倾,未发育有效圈闭,两期油气均未有效成藏。晚喜山期受南北向造山运动影响,石炭系地层发生翘倾作用,形成有效圈闭。同时,古生界的深大油源断裂复活,聚集在奥陶系古油藏中的油气沿断裂垂向调整至石炭系东河砂岩,并在北倾斜坡的背景下,油气自北向南短距离侧向运移,聚集于哈得逊石炭系圈闭中,形成现今哈得逊油藏。     

The Late-Quaternary deposits of the middle Dyfi Valley,Wales

The surficial deposits and landforms of the middle Dyfi Valley, Wales, are examined and a sequence of glacial, glacio-fluvial and glacio-lacustrine sediments is identified. This is considered to relate to a late stage in the wastage of the Late-Devensian Merioneth ice-cap. A sequence of terrace gravels overlying the giacigenic succession represents dissection during early Flandrian times.     

汝州煤田逆冲推覆、滑覆构造的形态特征

汝州煤田位于华北板块南缘逆冲推覆构造带豫西段前锋部位,区内逆冲推覆构造较发育。其滑脱面倾角浅部较陡,深部较缓,表现为上陡下缓、凹面向上的铲状形态,向深部逐渐交汇于同一断裂。该区构造在剖面上时而出现断坡,时而出现断坪,其变化与岩层的软硬程度等因素有关。通过对逆冲推覆、滑覆构造的特征分析,推断出该区推覆下掩盖的二1煤体构造形态特征。     

Kinematics of the Inntal shear zone–sub-Tauern ramp fault system and the interpretation of the TRANSALP seismic section, Eastern Alps, Austria

A new interpretation of the Inntal–Tauern sector of the TRANSALP seismic section is presented. One of the most prominent contrasts in reflectivity in the TRANSALP seismic section is the contact between the Bajuvaric unit in the footwall and the overlying Tirolic unit and its basement across a moderately south-dipping interface. We trace this contact from the surface at the southern margin of the Inn valley to a depth of 5 km. There, the contact is deformed or cut by the Tauern Window northern margin. We define the contact between Bajuvaric and Tirolic units as Brixlegg thrust, which is older than Miocene Tauern window exhumation and has a Paleogene age. The sub-Tauern ramp connects with the Inntal fault system at the surface and roots below the Tauern window. Oblique thrust movements across this fault system in the Miocene caused exhumation of the hanging wall, where the fault has a ramp geometry, which is in the area of the TRANSALP cross section and west of it. East of the TRANSALP cross section, the fault system merges with Alpine basal thrust, which is a flat. No Miocene exhumation occurred above the flat.     

前陆盆地的构造演化及其沉积、地层响应——以库车坳陷下白垩统为例

逆冲推覆构造近年来的研究表明,由于逆冲带内超压的反复积聚和释放,冲断活动表现为间歇式前展逆冲方式,且具有早期长周期低前展速率、晚期短周期高前展速率的特点,由此导致作用于前陆盆地的构造负载早期以垂向加载为主、晚期则以递进加载为主。库车坳陷下白垩统记录了一幕完整的前陆盆地构造演化过程,卡普沙良群和巴什基奇克组分别对应于逆冲期和构造宁静期,两者之间发生了地层几何形态的重大转变以及内部削截反射终止点的迁移。与早、晚期冲断活动特征对应,在前隆向前渊的斜坡带,卡普沙良群的下部和上部分别发育大套向逆冲带的前积反射和向克拉通方向的退积超覆反射。在紧邻造山带的前渊带,亚格列木组砾质粗碎屑沉积体标志着逆冲推覆的重新开始;巴西盖组三角洲体系的发育说明快速前展逆冲导致宽缓的楔顶带的形成;巴什基奇克组底部粗碎屑发育及其与巴西盖组之间沉积突变,反映为宁静期岩石圈强烈回弹的结果。最终,前陆盆地构造演化的逆冲期可细分为初始逆冲、?冲、前展逆冲、逆冲减弱—停滞等4个阶段。     

福建兴化湾外近海沉积物岩心放射性核素分布

用γ谱方法测定了采集自福建兴化湾外近海两个沉积物岩心中的放射性核素，探测到的核素为40K、137Cs、210Pb、226Ra、228Ra、228Th和238U，讨论了这些放射核素的垂直分布特征，用210Pb过剩方法估算了两个采样站位所在海域的沉积速率。发现两个站位的沉积速率存在明显差异，其原因是两个站位所在海区具有不同的海洋动力环境，从而使沉积物具有不同的物质构成。本文比较了两岩心中放射性的分布物征，探讨了其反映的沉积环境的特征，证明沉积物中放射性核素的分布与海区海洋环境存在的关系。     

印支运动对济阳坳陷构造形态形成演化的影响

三叠纪中期至侏罗纪早期的印支运动动力来源于华北板块与扬子板块的聚敛,聚敛作用形成巨大的NE-SW向挤压力首先导致济阳坳陷北西向压性构造的形成,产生了一系列NW向褶皱隆起带及其伴生的宽缓向斜,其次在对济阳盆地产生多处NW向挤压逆冲构造,伴之以褶皱构造。印支运动还造成本区地势起伏不平,剥蚀程度差异还导致相对隆起区与相对低洼区相间排列,上古生界保留较完整。     

粤港澳大湾区地下水资源特征及开发潜力

粤港澳大湾区是中国开放程度最高、经济活力最强的区域之一,在国家发展大局中具有重要的战略地位,大湾区未来的发展离不开水资源的支撑和良好的水生态环境。近年来,随着大湾区经济的快速发展,人口激增,需水量上升,水资源环境问题也日益突出,水安全保障程度不足;地下水是水资源的重要组成部分,具有水量稳定、水质较好的特点,可作为重要的应急备用水源。本文从地下水资源着手,系统梳理了大湾区水资源环境条件、地下水资源状况、特征和开发利用潜力,并提出了应急后备水源地建议,得到以下认识:(1)地下水可划分为松散岩类孔隙水、碳酸盐岩岩溶水、基岩裂隙水三大类,其中松散岩类孔隙水和基岩裂隙水分布最广;(2)湾区内地下水水化学类型较为复杂,丘陵山区以HCO_3-Na型、HCO_3-Ca型及HCO_3-Na+Ca型为主,冲积平原及山间盆地以HCO_3+Cl-Na型及HCO_3+Cl-Na+Ca型为主,三角洲地区以Cl-Na型微咸-咸水为主;(3)西江、北江及东江干流构成湾区内地下水排泄的总渠道,各支流为地下水的局部排泄基准面,地下水动态变化具季节性特征;(4)地下水整体水质较好,Ⅰ-Ⅲ类水占比高达66.25%,从丘陵山区到三角洲平原,水质呈变差趋势,尤其在广州、江门、中山、东莞等城市周边水质较差,超标因子主要为氨氮、氯化物、氟化物、硫酸盐等,三角洲地区发育大量"铁质水"和"氨氮水",水质性缺水问题突出;(5)地下水开发利用程度很低,东莞及中山等城市基本未开发利用地下水,在各类地下水中,碳酸盐岩岩溶裂隙水具有规模开采的开发利用潜力;(6)综合分析相关资料,提出将广花盆地等10处富水块段作为应急水源地备选,经初步计算每年可为大湾区提供约4.18亿m~3的应急水源保障。为应对突发性水质污染及极端干旱气候等大规模供水危机,保障粤港澳大湾区用水安全,促进大湾区高质量发展,建议加强大湾区的基础水文地质调查工作,掌握地下水的水位、水质、水量的动态变化特征,精准计算可用于应急备用开采的地下水储存量。