浊积岩和砂质碎屑流岩关键识别标志及辽河盆地岩心实例^*     

杨棵  朱筱敏  刘宇  刘兴周  郭峰 《古地理学报》2020,22(3):483-492

重力流是自然界中广泛存在的一种流体形式,不同学者基于不同切入点往往会提出多种重力流的划分方案。采用浊流和碎屑流的二分方案,对浊积岩和砂质碎屑流岩的沉积特征展开综述和探讨,旨在进一步概括这2类岩石的沉积特征,明确具有指示意义的最典型相标志。研究表明,在野外露头和钻井岩心中,可以通过以下典型特征鉴别浊积岩和砂质碎屑流岩: 砂岩内若发育以正粒序为特征的递变层理,则应该将其认定为浊积岩;若砂岩内发育泥岩撕裂屑、漂浮状泥砾或不含任何层理构造(块状砂岩),则应该将其认定为砂质碎屑流岩。这些特征是鉴别浊积岩和砂质碎屑流岩最可靠的标志。此外,变形层理、爬升波纹交错层理、波状层理、平行纹层、冲刷侵蚀界面、岩性突变界面和槽模等沉积构造也具有一定指示意义,出现这些特征时需要结合沉积背景、岩相的垂向组合关系和地球物理等资料进行综合判断。  相似文献   

Mineralogy,Fluid Inclusion,and Hydrogen and Oxygen Isotope Studies of the Intrusion‐Related Yangla Cu Deposit in the Sanjiang Region,SW China: Implications for Metallogenesis and Deposit Type     

Li‐Juan Du  Bo Li  Zhi‐Long Huang  Jun Chen  Jia‐Xi Zhou  Guo‐Fu Zou  Zai‐Fei Yan 《Resource Geology》2020,70(1):28-49

The Yangla deposit is an intrusion‐related Cu deposit in the Jinshajiang tectonic belt (eastern Sanjiang region, SW China). Despite extensive studies that have been conducted on this deposit, the relationship between the granitic magma and Cu mineralization is still unclear, and hence, the genesis is debated. To answer this question, we conducted an integrated study of mineralogy, fluid inclusions (FIs), and hydrogen and oxygen (H‐O) isotopes. Three mineralization stages were identified based on the ore textures, alteration zonation, and crosscutting relationships: (i) pre‐ore prograde skarn (stage I), with the garnet and pyroxene dominated by andradite and diopside, respectively; (ii) syn‐ore retrograde alteration (stage II), which is subdivided into the early syn‐ore stage (stage IIa) marked by retrograde hydrated mineral assemblages and significant Fe‐Cu‐Mo‐Pb‐Zn sulfide mineralization, and the late syn‐ore stage (stage IIb) featured by quartz‐calcite veins; and (iii) late supergene mineralization (stage III), which is characterized by secondary azurite and malachite. These results of mineralogy, FIs, and H‐O isotopes indicate that: (i) Cu mineralization has a close temporal, spatial, and genetic relationship with skarn alteration; (ii) the ore fluids were magmatic dominated with late‐stage meteoric water incursion; and (iii) Type‐S (halite‐bearing) and Type‐V (vapor‐rich) FIs coexisted in garnet and clinopyroxene of stage I, indicating that fluid boiling might have occurred during this stage. From stage I to stage IIa, the FI type transformed from Type‐S + Type‐V + Type‐L (liquid‐rich) to Type‐V + Type‐L with the conduct of mineralization and was accompanied by the disappearance of Type‐S, and homogenization temperature and salinity also tended to decrease dramatically, which may be caused by the deposition of skarn minerals. At stage IIa, boiling of the ore fluids still continued due to the change from lithostatic to hydrostatic pressure, which triggered the precipitation of abundant quartz‐Cu‐Mo‐Fe sulfides. Furthermore, fluid mixing between a high‐temperature magmatic fluid and a low‐temperature meteoric water might cause a considerable drop in temperature and the deposition of Cu‐bearing quartz/calcite veins during stage IIb. Hence, we consider the Yangla deposit to be of a skarn type, genetically related to the Mesozoic magmatism in the Sanjiang region.  相似文献   

Measurement of local and volumetric deformation in geotechnical triaxial testing using 3D-digital image correlation and a subpixel edge detection algorithm     

Wang  Pengpeng  Guo  Xiaoxia  Sang  Yong  Shao  Longtan  Yin  Zenan  Wang  Yudi 《Acta Geotechnica》2020,15(10):2891-2904

Based on the three-dimensional digital image correlation (3D-DIC) technique, the stereovision system has been applied to the improved triaxial apparatus to obtain 3D full-field deformation of the specimen during triaxial testing. Through the calibration process, the 3D-DIC technique can obtain the accurate specimen’s spatial displacement deformation. Meanwhile, a subpixel edge detection algorithm has been combined with 3D-DIC technique to calculate the radial strain and the volume strain of the specimen directly. Furthermore, a series of consolidated drained and undrained triaxial tests were carried out on Hainan (China) sand specimens and measured by the conventional and the image measurement methods. Compared to the results measured by the conventional method, the image measurement technique can obtain the more experimental data, such as the 3D displacement field of the whole specimen, the local strain distribution, and so on. The measurement results also show the conventional method would be disturbed by the end constraints in triaxial tests so that the strength of the soil would be overestimated. Meanwhile, the middle of the specimen would be selected to calculate the stress–strain relationship without the influence of the end constraints in the proposed method. Based on the image measurement results, the proposed method has the potential to be used in geotechnical tests for exploring the soil’s progressive failure behaviors, inhomogeneous deformation and mechanical characteristics.

  相似文献   

An experimental approach for determination of the Weibull homogeneity index of rock or rock-like materials     

Pan  Xiaohua  Guo  Wei  Wu  Shifan  Chu  Jian 《Acta Geotechnica》2020,15(2):375-391

Acta Geotechnica - The spatial variation of the physical–mechanical properties of rock or rock-like materials is an intrinsic characteristic of the materials induced by multiscale material...  相似文献   

A quantitative risk analysis model for cascade reservoirs overtopping: principle and application     

Zhou  Xingbo  Chen  Zuyu  Zhou  Jianping  Guo  Xinlei  Du  Xiaohu  Zhang  Qiang 《Natural Hazards》2020,104(1):249-277

Natural Hazards - Quantitative and effective flood control operation of cascade reservoirs under emergency conditions can guarantee the safety of dams, reduce the social loss caused by flood...  相似文献   

用数据模拟方法分析探空仪慢转对高空气象探测记录结果的影响     

邱高林  郭斌 《高原山地气象研究》2005,25(3)

本文提出了一种用数据模拟的方法,分析因探空仪慢转对高空气象探测记录造成影响的情况,并结合了一次实际探空记录进行了分析论证,得出在实践中用五九型探空仪,在其转速下低于3转/分时的情况下,所探测到的高空压、温、湿资料与转速保持在5～8转/分的情况下的资料,吻合程度较高.而转速保持在记录整理与否的临界点:2转/分时～500 hPa以上＜2转/分,此时各要素的偏离程度已明显加大,对大气层结特征的反映,已失去指示性.  相似文献   

山东招掖金矿带原生金矿化地球化学特征的数学地质研究          下载免费PDF全文

郭光裕  林卓虹  张俊岭  朱学文  丛桂新 《地质找矿论丛》1989,(1):67-89

本文主要是应用数学地质方法研究山东招掖金矿带原生金矿化地球化学特征,从而确定金矿化的最佳地球化学标志组合,并建立原生金矿化模式及金矿体原生晕的判别模式.  相似文献   

T形截面柱的非线性分析   总被引：6，自引：0，他引：6  

李晓莉  郭棣  吴敏哲 《世界地震工程》2005,21(3):122-125

编制了适用于任意截面的钢筋混凝土压弯构件截面的弯矩—曲率非线性分析程序。在此基础上,计算了考虑非线性变形的异形柱弯矩—曲率关系,并研究了翼缘、轴压比等因素对异形柱强度和延性的影响,可作为异形柱研究的参考依据。  相似文献   

非点源污染的流域分配方法研究   总被引：1，自引：1，他引：0  

黎薇  郭雅芬  王琦  过仲阳 《上海国土资源》2005,(3):31-34,21

农业非点源污染的流域分配研究对于提高环境质量具有重要的现实意义。根据遥感技术得到的土地利用类型、河网、道路、圩区等信息,结合地理信息系统（GIS）的空间分析功能,对非点源污染负荷进行了定量计算及可视化分析,在此基础上,得到各主要河段的污染分配量,这可为寻求流域内合理的土地利用模式和农业非点源污染排放总量的控制方法提供决策依据。  相似文献   

The role of salinity in fluvio-deltaic morphodynamics: A long-term modelling study     

Zeng Zhou  Luying Chen  Jianfeng Tao  Zheng Gong  Leicheng Guo  Mick van der Wegen  Ian Townend  Changkuan Zhang 《地球表面变化过程与地形》2020,45(3):590-604

Salinity difference between terrestrial river discharge and oceanic tidal water plays a role in modifying the local flow field and, as a consequence, estuarine morphodynamics. Although widely recognized, recent numerical studies exploring the long-term morphological evolution of river-influenced estuaries with two-dimensional, depth-averaged models have mostly neglected salinity. Using a three-dimensional morphodynamic model, we aim to gain more insight into the effect of salinity on the morphodynamics of fluvio-deltaic systems. Model results indicate that the resultant estuarine morphology established after 600 years differs remarkably when a salinity gradient is included. A fan-shaped river-mouth delta exhibits less seaward expansion and is cut through by narrower channels when salinity is included. The inclusion of salinity tends to generate estuarine circulation, which favours landward sediment transport and hence limits the growth of the delta while enhancing the development of intertidal areas. The formation of deltaic channel–shoal patterns resulting from morphodynamic evolution tends to strengthen salinity stratification, which is characterized by an increased gradient Richardson number. The direction of the depth-averaged residual sediment transport over a tide may be opposite to the direction of residual velocity, indicating the significant influence of baroclinic effects on the net sediment transport direction (and hence morphological change). The effect of salinity on morphological evolution becomes less profound when the strength of tidal or fluvial forcing is dominant over the other. The effects of sediment type and flocculation, which are particularly important when salinity gradients are present, are also discussed. Overall, this study highlights that neglecting salinity to simulate long-term estuarine morphodynamics requires more careful justification, particularly when the environment is characterized by fine sediment types (favouring suspended transport), and relatively large river discharge and estuarine depth (favouring baroclinic effects). © 2020 John Wiley & Sons, Ltd.  相似文献