新疆哈密沙泉子地区断裂构造航空重磁遥特征及相关性分析

为了研究航空物探（重、磁）及遥感在断裂构造研究中的关系,利用新疆哈密沙泉子地区开展的航空物探（重、磁）遥感调查数据,开展了该区断裂构造划分,共划分断裂构造18条。对划分的18条断裂进行了重磁遥特征及相关性分析,结果显示,区内所划分的一、二级断裂均为重磁遥相关,重磁遥相关的三级断裂也是与主体构造格架方向一致的断裂;重磁、磁遥相关断裂均为三级断裂,不相关断裂也是三级断裂。总体上,利用重磁遥资料进行大断裂或主体格架断裂划分时关联性更好。     

A coupled discrete element model for the simulation of soil and water flow through an orifice

Soil erosion around defective underground pipes can cause ground collapses and sinkholes in urban areas. Most of these soil erosion events are caused by fluidization of the surrounding soil with subsequent washing into defective sewer pipes. In this study, this soil erosion process is simplified as the gradual washout of sand particles mixed with water through an orifice. The discrete element method is used to simulate the large deformation behavior of the sand particles, and the Darcy fluid model is coupled with this approach to simulate fluid flow through porous sand media. A coupled 3D discrete element model is developed and implemented based on this scheme. To simulate previous experiments using this coupled model considering the current computing capacity, we incorporated a ‘supply layer’ to study the continuous erosion process. The coupled model can predict the erosion flow rates of sand and water and the shape of erosion void. Thus, the model can be used as an effective and efficient tool to investigate the soil erosion process around defective pipes. Copyright © 2017 John Wiley & Sons, Ltd.     

广东雷州珍稀海洋生物国家级自然保护区 海水环境质量状况分析与评价

2018年9月和12月,两次调查了广东雷州珍稀海洋生物国家级自然保护区海域海水的环境质量。结果表明,该保护区平均综合水质指数为0.38,一类海水平均达标率为93.59%,海水中铅、磷酸盐、锌的含量达标率偏低,分别为53.85%、73.1%、96.15%。12月保护区海水中的无机氮、磷酸盐、溶解氧、叶绿素a含量明显高于9月,保护区实验区和缓冲区站位的水质优于核心区站位的水质。该保护区海域综合水质定性评价结果为优。靠近康港附近站位的营养盐相对偏高,磷酸盐的平均达标率仅为73.1%,因此,需加强对康港附近海域养殖情况的监控,尽量减少养殖废水对保护区海域的排放,保持保护区海水清洁,以利于对保护区内珍稀海洋生物及其栖息地的保护。     

Constraining basin thermal history and petroleum generation using palaeoclimate data in the Piceance Basin,Colorado

Careful assessment of basin thermal history is critical to modelling petroleum generation in sedimentary basins. In this paper, we propose a novel approach to constraining basin thermal history using palaeoclimate temperature reconstructions and study its impact on estimating source rock maturation and hydrocarbon generation in a terrestrial sedimentary basin. We compile mean annual temperature (MAT) estimates from macroflora assemblage data to capture past surface temperature variation for the Piceance Basin, a high‐elevation, intermontane, sedimentary basin in Colorado, USA. We use macroflora assemblage data to constrain the temporal evolution of the upper thermal boundary condition and to capture the temperature change with basin uplift. We compare these results with the case where the upper thermal boundary condition is based solely upon a simplified latitudinal temperature estimate with no elevation effect. For illustrative purposes, 2 one‐dimensional (1‐D) basin models are constructed using these two different upper thermal boundary condition scenarios and additional geological and geochemical input data in order to investigate the impact of the upper thermal boundary condition on petroleum source rock maturation and kerogen transformation processes. The basin model predictions indicate that the source rock maturation is very sensitive to the upper thermal boundary condition for terrestrial basins with variable elevation histories. The models show substantial differences in source rock maturation histories and kerogen transformation ratio over geologic time. Vitrinite reflectance decreases by 0.21%Ro, source rock transformation ratio decreases 10.5% and hydrocarbon mass generation decreases by 16% using the macroflora assemblage data. In addition, we find that by using the macroflora assemblage data, the modelled depth profiles of vitrinite reflectance better matches present‐day measurements. These differences demonstrate the importance of constraining thermal boundary conditions, which can be addressed by palaeotemperature reconstructions from palaeoclimate and palaeo‐elevation data for many terrestrial basins. Although the palaeotemperature reconstruction compiled for this study is region specific, the approach presented here is generally applicable for other terrestrial basin settings, particularly basins which have undergone substantial subaerial elevation change over time.     

Contemporary processes of environmental information in the atmosphere-glacier-runoff system in an area of typical monsoon temperate glacier

Sampling was carried out at Baishui No. 1, the largest glacier on Mt. Yulong, China, during the summers of 1999 and 2000, to investigate the spatial variations of oxygen isotopes in the atmosphere-glacier-river system. The results confirm that there is an inverse relation between the oxygen isotopic composition of precipitation and air temperature/precipitation amount. This suggests that a strong “precipitation amount effect” exists in this typical monsoon temperate-glacier region. There are marked differences of the δ¹⁸O values of winter-accumulated snow, glacial meltwater, summer precipitation and the glacier-fed river water. Spatial and temporal variations of isotopic composition are controlled by climatic conditions. Isotopic fractionation and differentiation occur during phase changes, snow-to-ice and ice-to-meltwater transformations, and runoff processes. Variations of stable isotopes in glacier runoff can indicate variations of sources of supply, as well as different discharge-related processes. Ionic changes occur as a result of meltwater contact with glacier bed materials.

     

岷县-漳县MS6.6地震前后甘肃前兆异常及响应特征

分析总结了2013年7月22日甘肃岷县—漳县MS6.6地震前后甘肃前兆台网观测资料变化情况,发现该地震前有7个台站、4种观测手段、14个测项出现了明显的异常,既有长期、中长期异常,也有短期和短临异常,说明对资料的分析既要看短期变化,还要看中期和长期变化。出现异常测点的震中距多数在200 km范围之内。另外部分水位、流量和水温测点的资料记录到不同程度的同震效应;形变观测多数测点记录到比较明显的同震响应,记录同震响应的测点与震中位置、方向、距离无明显关系。     

不同含水率下滑坡滑带土动力特性试验研究

甘肃舟曲泄流坡滑坡地处活跃断层破裂带内,断层活动控制着该滑坡的发育和运动。为了研究该滑坡滑带土的动力特性,采用重塑滑带土样,在固结不排水条件下,利用分级循环加载法开展动三轴试验,重点探讨含水率的变化对滑带土动力特性的影响规律。试验结果表明:含水率一定时,泄流坡滑坡滑带土的动弹性模量随动应变的增大呈指数形式减小;动应变一定时,动弹性模量随含水率的增大而不断减小,且衰减速率随含水率的增大而增大;含水率并不影响动弹性模量-动应变关系曲线的形态,不同含水率下该关系曲线可以进行归一化。滑带土阻尼比随含水率的增大而增大,阻尼比-动应变关系曲线也具有归一化特征。不同含水率下泄流坡滑带土动应力-应变本构关系可以用双曲线模型进行描述。     

多波束测深成果精度评估方法探讨

为检验多波束测深成果质量,需对测深数据处理结果作精度评估。国内诸多规范规定了利用主检测线交叉点不符值计算均方根差的评估方法,但在实际应用时由于均方根差值受水深深度影响异常明显,无法合理表达测量结果的好坏,对测量精度评估意义不明显。为更客观反映多波束测深成果精度,提出统一采用相对误差作水深测量精度评估指标的方法,对主检不符值具体计算方法给出了若干建议。     

蒙新高原岱海夏季叶绿素a浓度空间分布及影响因子

基于2019年夏季(8月)对岱海水样的实测数据分析,通过运用克里金插值、相关性分析、多元线性逐步回归、主成分分析方法,探究了叶绿素a(Chl.a)的空间分布特征及其与水环境因子的相关关系,并讨论了相应的防治措施。研究显示:Chl.a空间分布呈现由岸边向湖心递减的趋势,总氮(TN)、总磷(TP)、氨氮(NH₃-N)、硝态氮(NO^-₃-N)、正磷酸盐(PO^3-₄-P)空间分布特征与Chl.a空间分布特征相近,采样期内岱海湖局部区域水质状况已达到富营养状态;Chl.a与浊度(Turbidity)、TP、TN、悬浮物(SS)、pH、NO^-₃-N、NH₃-N、PO^3-₄-P、蓝绿藻丰度(CYANO)呈极显著正相关,与溶解氧(DO)呈显著负相关,与电导率(Cond.)呈正相关、与氮磷比(TN/TP)呈负相关;各湖区Chl.a与环境因子相关关系不同,全湖逐步线性回归方程为Y_Chl.a=-21.42+8.658X_pH-0.865X_DO+0.779X_NH3-N+0.699X_Turbidity+0.502X_CYANO;岱海不同湖区因子对Chl.a浓度的影响存在差异,各湖区Chl.a与环境因子相关关系不同,通过岱海与我国其他湖泊Chl.a与环境因子的相关性关系对比分析,湖泊地理属性差异及营养物质输入浓度是影响Chl.a变化的重要因素;本研究岱海的TN/TP平均值为12.23,说明夏季岱海湖Chl.a变化为氮磷共同限制。     

汶川地震对湖北地震活动趋势的影响

探讨汶川地震对湖北地震活动的影响,认为龙门山断裂带与襄樊-广济构造带同属于扬子板块西部和北部边缘,是扬子板块逆冲插入青藏板块和秦岭微板块之下形成的。历史强震统计结果表明,四川中西部及周边强震活动对湖北及周边地区中强地震活动影响明显,且对应率较高。汶川地震后3年内,湖北及周边地区具有发生中等强度地震的可能。同时也指出,近几年湖北及周边的地震活动是汶川地震前期东部地区应力场调整的结果。