冈底斯中段格达地区典中组火山岩锆石U-Pb年龄和地球化学特征

青藏高原南部广泛发育的林子宗火山岩蕴涵着新特提斯洋俯冲与印度—亚洲大陆碰撞过程的地质信息。为探讨冈底斯中段格达地区典中组火山岩的形成时代、岩浆源区及构造环境等特征,对其开展了LA-ICP-MS锆石U-Pb同位素测年和地球化学特征研究。研究结果表明: 该地区典中组火山岩锆石U-Pb年龄为(61.6±1.0) Ma; 典中组火山岩相对富集LILE和LREE、亏损HFSE,具典型岛弧火山岩的特征; 岩浆源区主要来源于地壳物质部分熔融,是俯冲岛弧构造环境下新特提斯洋北向俯冲消减过程的产物。     

Study on the response of postside-grouted piles subjected to lateral loading in calcareous sand

Acta Geotechnica - The post-grouting technique has gradually become an effective approach to improve the bearing capacity of piles in calcareous sand due to its simple process, low cost and...     

盐穴能源储库氮气阻溶造腔气垫控制理论研究

盐穴具有良好的稳定性和密闭性,是储存天然气、石油、氢气等的理想场所。传统水溶造腔采用的油垫阻溶存在阻溶效果差、卤水油污重等问题,无法满足绿色矿山建设要求。气垫作为一种替代品备受关注,但因其起步较晚、控制难度大,加之我国复杂的盐层地质条件,阻碍着其推广应用。为此,首先分析了不同造腔阶段气垫控制特点,然后在对气-液界面处压力平衡分析的基础上提出了不同阶段气垫厚度预测及注气量计算方法,结合某井建槽期实例给出了建议气垫厚度及其波动范围,探明了气垫厚度和注气量随造腔推进的变化规律,最后探讨了气垫阻溶应用相关的关键问题。研究结果表明：建槽期及收顶期以气垫厚度控制为主,建腔期及腔体修复阶段则以气-液界面位置控制为主。建议建槽期平均气垫厚度不低于0.3 m,建槽期初期气垫厚度波动迅速,应设置较大的气垫厚度并及时补注氮气,随后气垫厚度波动趋于稳定,补气时间间隔可逐渐拉长。随造腔时间增加,单次补气量越来越大,累计补气量整体呈线性增长。造腔过程中井口气压及气-液界面处气垫压力先增加后线性减小,应实时监测井口气压变化。气垫阻溶与油垫阻溶成本相近但环境效益显著,可重复利用排出氮气及井口注气设施以节约成本。现场应...     

趋势面分析在高原地区音频大地电磁测深中的应用

常规音频大地电磁法,如EH-4电磁成像系统,在资料处理时通常不能有效分辨部分异常区域。以青海海北某公路隧道勘探为例,研究趋势面分析法在音频大地电磁测深中的应用。结果表明：通过拟合趋势面方程,可获取研究区内任一位置的视电阻率值,在拟合度较高的情况下可对区外的视电阻率值进行预测与估计;野外观测数据通常受随机因素的影响,可通过趋势面分析法对随机噪声进行平滑滤波处理;剩余值反映了视电阻率异常特征,绘制剩余值等值线图可以在去除区域背景视电阻率值后对异常区域进行凸显。音频大地电磁探测成果与趋势面分析法结合能更充分地利用地质信息。     

Haze risk: information diffusion based on cellular automata

Natural Hazards - Negative effects of haze risk can easily spread faster and more widely, however, existing studies rarely investigate the whole period or cycle of diffusion events, which leads to...     

基于ELMO-CNN-BiLSTM-CRF模型的地质实体识别

地质实体是地质文本中的关键和核心信息,对其准确识别是地质信息提取和挖掘的重要前提.设计了ELMO-CNN-BiLSTM-CRF模型,基于预训练字向量构建深层BiLSTM-CRF神经网络模型,通过添加词语动态特征以及词语字符级别的特征,弥补字向量特异性缺失的问题,提高对于地质文本中复杂多词义的识别水平和对地质实体局部特征的提取能力.以《西藏自治区谢通门县雄村铜矿勘探地质报告》为例,对该模型的性能进行了评估,模型的准确率、召回率和F1值分别为95.15%、95.26%和95.21%.实验表明相比BiLSTM-CRF和CNN-BiLSTM-CRF模型,该模型在小规模语料地质实体识别方面效果更优,且能够有效识别长地质实体词汇和地质多义词.      

Formation of the modern current system in the East China Sea since the early Holocene and its relationship with sea level and the monsoon system

The Okinawa Trough is a natural laboratory for the study of air-sea interaction and paleoenvironmental change. It has been demonstrated that present offshore export of particles in the bottom nepheloid layer occur primarily with downwelling from the northeast winter monsoon, which is inhibited by a transverse circulation pattern in summer. This current system was very different during the Last Glacial Maximum owing to low sea level(-120 m) and exposure of a large shelf area. We collected sediment core Oki01 from the middle Okinawa Trough during 2012 using R/V K exue No. 1 to elucidate the timing and cause of the current system transition in the East China Sea. Clay mineral, dry density, and elemental(Ti, Ca) composition of core Oki01 was analyzed. The results indicate that clay minerals derived mainly from the Huanghe(Yellow) and the Changjiang(Yangtze) Rivers during 16.0–11.6 ka, and the modern current system in the East China Sea formed beginning in the early Holocene. Therefore, mixing of East China Sea continental shelf, Changjiang River and partially Taiwan Island sediment are the major contributors. The decrease of log(Ti/Ca) and alternating provenance since the early Holocene indicate less sediment from the East China in summer because of resistance of the modern current system, i.e., a "water barrier" and upwelling. Conversely, sediment delivery persists in winter and log(Ti/Ca) indicates the winter monsoon signal since the early Holocene. Our evidence also suggests that sediment from Taiwan Island could be transported by the Kuroshio Current to the middle Okinawa Trough, where it mingles with winter monsooninduced export of sediment from the Changjiang River and East China Sea continental shelf. Although the present research advances understanding of the evolutionary history of paleoenvironmental change in the Okinawa Trough, more sediment cores should be retrieved over wide areas to construct a larger scenario.     

矿田构造与岩浆-热力构造的类型划分及青海实例分析

多个造山带和盆地矿田地质调研发现,热力作用和热力构造有其广泛性和特殊性。岩浆-热力构造是指受岩浆-热力作用影响或控制,与岩浆侵入或火山喷发活动有一定联系,形成于岩浆岩体中或围岩地层中或远程热力作用影响区的一系列热力(含部分应力作用)形成的构造类型。在矿田、矿田地质和矿田构造的概念及类型划分研究基础上,提出了矿田构造和岩浆-热力构造的类型划分方案。按成矿期构造形成的主控作用方式,将矿田构造划分为:应力、热力、重力和复合转化4种构造类型。按照矿田岩浆活动-热力作用对成矿作用的控制影响深度、构造环境和成矿类型,将矿田岩浆-热力构造分为五大类24个亚类:1近地表热水喷流沉积-地热异常群集型;2热液型;3岩浆侵入-斑岩-矽卡岩-韧性剪切流变-热穹窿型;4岩浆通道-小岩体矿床-壳幔混合成矿型;5地幔热柱型。这些不同深度的岩浆-热力构造形成了不同类型的矿床,在壳幔岩浆-热力构造作用下,经常形成重要矿床类型组合和超大型矿床。对盐丘、岩浆热穹窿、地热异常、壳幔热柱等几种特殊类型的岩浆-热力构造进行了简要的特征分析。以青海祁漫塔格矿带景忍—虎头崖多金属矿田为实例,在矿田地质学指导下,以矿田建造和构造-岩相填图为基础,剖析矿区岩浆-热力构造特征,归纳其岩浆-热力构造类型为斑岩型+矽卡岩型+断控热液型,认为晚三叠世岩浆侵入作用是该区多金属大规模成矿的主要内因,岩浆侵入作用与各时代碳酸盐岩接触带形成了矽卡岩矿床,并且显示出印支期岩浆侵入体、斑岩、矽卡岩带、多组断裂破碎带和热液蚀变带的发育与找矿富集中心紧密套合,不同方向断裂控矿作用不同,近EW向和NWW向断裂控矿显著,矿田中深部成矿潜力较大。