基于相干特征的岩石薄片序列图像边缘提取及颗粒分割

针对岩石颗粒边缘模糊、结构复杂的特点,为了更有效地识别颗粒边缘,在基于特征值的C3相干算法的基础上,融合多尺度和多角度的特征表达,提出了一种改进的C3相干算法。该算法综合考虑岩石薄片图像角度域光学特征、空间尺度信息和各向异性信息,能更有效地表征颗粒边缘特征,表现出对复杂矿物结构的适应能力。在采集的岩石薄片正交偏光图像上验证提出的算法,实验结果表明,与原生C3相干算法相比,改进后的C3相干算法在全局图像上的方差和灰度差分乘积分别提升了68.41%和22.91%,信息熵下降了21.61%。     

基于随机补片和DeepLabV3+的建筑物遥感图像变化检测

为有效解决传统遥感图像变化检测预处理复杂的问题,提出一种基于随机补片和DeepLabV3+的建筑物遥感图像变化检测方法。以ResNet50特征提取网络为基础,创建DeepLabV3+语义分割网络,并在图像和标签中创建大小为224像素×224像素的随机补片作为网络输入,训练建筑物提取网络;修改建筑物提取网络输入层为6通道,通过矩阵运算将两期遥感图像转换为一幅6通道非RGB图像,利用转换后的非RGB图像进行网络训练并验证变化检测精度。实验1利用ENVI5.3软件,采用马氏距离法进行变化检测;实验2采用改进的U-Net网络和随机补片,完成网络训练和精度验证;实验3使用实验2的训练数据和验证数据,采用随机补片和DeepLabV3+网络进行变化检测网络训练及精度验证。实验结果表明,该方法实验1、实验2、实验3建筑物变化检测平均交并比分别为24.43%、83.14%、89.90%,边界轮廓匹配分数分别为61.47%,80.24%、96.51%。     

坦桑尼亚林迪地区纳钦圭阿石墨矿床地质特征及找矿模型

坦桑尼亚林迪地区是世界上重要的石墨成矿带,纳钦圭阿石墨矿是成矿带新发现的典型矿床之一。矿区分南北2个矿段,共圈定工业矿体17条,推断石墨矿物资源量>100万t,固定碳平均品位为4.05%。矿体赋存于石墨片岩-片麻岩中,呈层状、透镜状产出,走向北东—北北东,产状与围岩一致,矿体与围岩呈渐变过渡关系。矿石类型为石墨片岩-片麻岩型,矿石矿物为鳞片状石墨,脉石矿物主要为石英、长石、云母及少量金属矿物。矿石中片度≥147 μm（+100目）的石墨占94.43%,工业类型为大鳞片晶质石墨矿石。以视极化率6%为异常下限,共圈定4处激电异常,高极化率异常与低电阻率异常对应良好,探矿工程确定为矿体出露位置。该石墨矿的找矿模型：新元古代莫桑比克活动带中一套中高级副变质岩系为区域找矿标志,石墨片岩、石墨片麻岩露头为矿区找矿的直接标志,延伸方向与地层走向一致的条带状低阻、高极化异常带为地球物理找矿标志。该石墨矿的地质特征及找矿模型可作为在坦桑尼亚寻找同类矿床的参考。     

Geochronological and geochemical evidence for a Late Ordovician to Silurian arc-back-arc system in the northern Great Xing'an Range,NE China

The early Paleozoic tectonic evolution of the Xing'an-Mongolian Orogenic Belt is dominated by two oceanic basins on the northwestern and southeastern sides of the Xing'an Block,i.e.,the Xinlin-Xiguitu Ocean and the Nenjiang Ocean.However,the early development of the Nenjiang Ocean remains unclear.Here,we present zircon U-Pb geochronology and whole-rock elemental and Sr-Nd isotopic data on the gabbros in the Xinglong area together with andesitic tuffs and basalts in the Duobaoshan area.LA-ICP-MS zircon U-Pb dating of gabbros and andesitic tuffs yielded crystallization ages of 443-436 Ma and 452-451 Ma,respectively.The Early Silurian Xinglong gabbros show calc-alkaline and E-MORB affinities but they are enriched in LILEs,and depleted in HFSEs,with relatively low U/Th ratios of 0.18-0.36 andεNd(t)values of-1.6 to+0.5.These geochemical features suggest that the gabbros might originate from a mantle wedge modified by pelagic sediment-derived melts,consistent with a back-arc basin setting.By contrast,the andesitic tuffs are characterized by high MgO(>5 wt.%),Cr(138-200 ppm),and Ni(65-110 ppm)contents,and can be termed as high-Mg andesites.Their low Sr/Y ratios of 15.98-17.15 and U/Th values of 0.24-0.25 and moderate(La/Sm)_n values of 3.07-3.26 are similar to those from the Setouchi Volcanic Belt(SW Japan),and are thought to be derived from partial melting of subducted sediments,and subsequent melt-mantle interaction.The Duobaoshan basalts have high Nb(8.44-10.30 ppm)and TiO2 contents(1.17-1.60 wt.%),typical of Nb-enriched basalts.They are slightly younger than regional adakitic rocks and have positiveεNd(t)values of+5.2 to+5.7 and are interpreted to be generated by partial melting of a depleted mantle source metasomatized by earlier adakitic melts.Synthesized with coeval arc-related igneous rocks from the southeastern Xing'an Block,we propose that the Duobaoshan high-Mg andesitic tuffs and Nbenriched basalts are parts of the Late Ordovician and Silurian Sonid Zuoqi-Duobaoshan arc belt,and they were formed by the northwestern subduction of the Nenjiang Ocean.Such a subduction beneath the integrated Xing'an-Erguna Block also gave rise to the East Ujimqin-Xinglong igneous belt in a continental back-arc basin setting.Our new data support an early Paleozoic arc-back-arc model in the northern Great Xing'an Range.     

Compression behavior of MICP-treated sand with various gradations

Acta Geotechnica - One-dimensional compression tests on quartz sands treated by microbially induced carbonate precipitation (MICP) were carried out to evaluate the effects of gradation and calcium...     

Investigation of the penetration characteristics of snake skin-inspired pile using DEM

Acta Geotechnica - Snake can perfectly utilize its scales to move. Inspired by the snake scales, this study investigated the characteristics of the snake skin-inspired pile penetration process. Six...     

A generalized model for effective thermal conductivity of soils considering porosity and mineral composition

Acta Geotechnica - Soils have a variety of mineral compositions. Although a number of thermal conductivity models have been developed for soils, few quantitatively investigated the effect of...     

Carboniferous ridge subduction in the Xingmeng Orogenic Belt: Constraints from geochronological,geochemical, and Sr-Nd-Hf isotopic analysis of strongly peraluminous granites and gabbro-diorites in the Xilinhot micro-continent

The Xingmeng Orogenic Belt evolved through a long-lived orogeny involving multiple episodes of subduction and accretion. However, there is a debate on its tectonic evolution during the Late Paleozoic. Here, we report geochemical, geochronological, and isotopic data from strongly peraluminous granites and gabbro-diorites from the Sunidzuoqi–Xilinhot region. Zircon U–Pb ages suggest that the intrusive rocks were emplaced during the Early Carboniferous (333–322 Ma). The granites exhibit geochemical characteristics similar to S-type granites, with high SiO₂ (72.34–76.53 wt.%), Al₂O₃ (12.45–14.65 wt.%), and A/CNK (1.07–1.16), but depleted Sr, Nb, and Ta contents. They exhibit positive ε_Nd(t) and ε_Hf(t) values (?0.3 to 2.8 and 2.7–5.7, respectively) and young Nd and Hf model ages (T_DM2(Nd)=853–1110 Ma and T_DM2(Hf)=975–1184 Ma), suggesting that they may be the partial melting products of heterogeneous sources with variable proportions of pelite, psammite, and metabasaltic rocks. The meta-gabbro-diorites from the Maihantaolegai pluton have low SiO₂ (47.06–53.49 wt.%) and K₂O (0.04–0.99 wt.%) contents, and demonstrate slight light rare earth element (REE) depletion in the chondrite-normalized REE diagrams. They have high zircon ε_Hf(t) values (14.41–17.34) and young Hf model ages (T_DM2(Hf)= 230–418 Ma), indicating a more depleted mantle source. The variations of the Sm/Yb and La/Sm ratios can thus be used to assess the melting degree of the mantle source from 5% to 20%, suggesting a quite shallow mantle melting zone. We propose that the petrogenesis and distribution of the strongly peraluminous granites and gabbro-diorites, as well as the tectonic architecture of the region, can be explained by a ridge subduction model. Based on these results, and previous studies, we suggest a southward ridge subduction model for the Sunidzuoqi–Xilinhot region.     

Pore structure and heterogeneity of shale gas reservoirs and its effect on gas storage capacity in the Qiongzhusi Formation

Fine characterization of pore systems and heterogeneity of shale reservoirs are significant contents of shale gas reservoir physical property research.The research on micro-control factors of low productivity in the Qiongzhusi Formation(Fm.)is still controversial.The lower Cambrian Qiongzhusi Fm.in the Qujing,Yunnan was taken as the object to investigate the influence of mineral compositions on the phys-ical properties of the reservoir and the heterogeneity of shale,using the algorithm to improve the char-acterization ability of Atomic Force Microscopy(AFM).The results showed that:(1)The pores are mainly wedge-shaped pores and V-shaped pores.The pore diameter of the main pore segment ranges from 5 to 10 nm.Mesopores are mainly developed in the Qiongzhusi Fm.shale in Well QD1,with the average pore diameter of 6.08 nm.(2)Microscopic pore structure and shale surface properties show strong hetero-geneity,which complicates the micro-migration of shale gas and increases the difficulty of identifying high-quality reservoirs.(3)The increase of clay mineral content intensifies the compaction and then destroys the pores.Conversely,brittle minerals can protect pores.The support and protection of brittle minerals to pores space depend on their content,mechanical properties and diagenesis.(4)Compression damage to pores,large microscopic roughness and surface fluctuations and strong pore structure heterogeneity are the reasons for the poor gas storage capacity of the Qiongzhusi Fm.,which will lead to poor productivity in the Qiongzhusi Fm.     

基于暴雨内涝模型的天津市西青区中小河流暴雨洪涝灾害评估

利用ARCGIS对天津市西青区的高精度地理信息数据、排水设施和排水方式进行预处理,以西青区下垫面和明渠河道的水流运动为模拟对象,建立天津市西青区中小河流暴雨洪涝仿真模型。以区内14条二级河道的水位变化作为模型的动态侧边界条件,针对2016年7月20日的大暴雨过程,设计了4个模拟方案,对河道高水位及暴雨造成的洪涝淹没过程进行评估,并将模拟结果与实际调查内涝灾情进行对比,结果表明,模型可以较客观地反映暴雨和河道水位变化对城镇造成的内涝灾害情况。