鞍山、本溪地区鞍山群变质岩岩石化学研究及条带状铁矿的成矿条件

通过对鞍山群变质岩石及条带状铁矿的岩石化学研究,探讨了鞍本地区太古宙老变质岩(正变质岩为斜长角闪岩及中酸性变粒岩等;副变质岩主要为泥质—泥灰质岩及硅铁质胶体化学沉积岩石)岩石学特征,并恢复变质前之原岩建造。太古宙条带状铁矿石的化学成分较单一;SiO_2、Fe_2O_3、FeO之和为85—95％,是一种成分很纯的磁铁矿石。作者从矿体的产状呈层;与围岩之间基本整合;条带状构造所显示的原生层理;铁矿石成分简单以及在世界上的分布情况表明它是海底火山沉积矿床。本文基于铁矿成因和与原岩建造的关系,进而讨论了铁矿的赋存     

济阳坳陷石炭-二叠系热演化与生烃阶段

在对胜利油气区济阳坳陷地质构造和沉积埋藏史分析的基础上 ,选择典型钻井岩芯 ,通过系统分析研究其镜质体反射率剖面特征 ,运用热动力学原理经线性回归确定出本区上古生界、中生界和新生界的古地温梯度 ,其分别为 3.49～ 3.92℃ / 10 0m、4.33～ 4.6 7℃ / 10 0m和 3.76℃ / 10 0m。中生代本区出现的高热异常与燕山期岩浆活动板底垫托作用有关。同时确定出印支运动和燕山运动抬升之前 ,石炭 二叠系烃源岩的成熟度分别为R° =0 .5 2 %～ 0 .5 8%和R° =0 .90 %～ 1.11% ,它们分别已进入生烃门限和生气阶段 ,但生烃产物不同程度地遭受构造抬升作用的破坏 ,这对正确评价本区石炭 二叠系油气资源具有十分重要的意义。     

灰色稳健总体最小二乘估计及高铁路基变形预测

最小二乘估计和部分变量误差模型的总体最小二乘估计不具备抵御粗差的能力。鉴于粗差可能同时出现在灰色白化微分方程的观测值和系数矩阵中,本文提出基于IGGⅢ抗差方案的部分变量总体最小二乘稳健估计。结合仿真数据和高铁路基观测数据,系统地比较稳健最小二乘、部分变量总体最小二乘、本文算法参数估计结果和算法稳定性。结果表明,本文算法预测精度高,可以应用到高铁路基沉降预测中。     

大别山及其周边现今垂直形变研究

基于1980年、2005年和2015年3期区域精密水准网观测资料,利用线性动态平差模型计算获取大别山地区水准网长期垂直运动速度场图像。研究发现,淮河平原地表下沉较为严重,大别山呈现弱隆升趋势运动,长江谷地边缘地区较大别山区呈现明显的隆升运动。跨郯庐断裂带水准剖面结果显示,垂直运动与地形呈负相关和弱相关。     

国内外岩溶塌陷监测方法综述

岩溶塌陷是全球广泛分布的地质灾害问题,严重影响和制约了岩溶地区社会、经济发展,因此,开展岩溶塌陷监测工作,对塌陷预测预报具有及其重要的作用。岩溶塌陷的监测技术与塌陷形成的机理关系密切。该文分析了岩溶塌陷的分布规律和形成的条件,系统总结了国内外岩溶塌陷的监测内容、技术方法、各自优缺点,如BOTDR监测、TDR监测、地质雷达监测、水动力条件监测及地-沉降等方法,为系统性地开展岩溶塌陷监测工作提供技术和方法参考,展望了未来的岩溶塌陷监测工作,认为岩溶塌陷监测需结合塌陷的形成机理、塌陷地区覆盖层特征及水动力条件,综合利用多种监测手段联合进行,并形成完善的监测网络。     

一种基于熵权法的小波去噪复合评价指标

传统的评价指标在真值未知的情况下不能满足小波去噪质量评价的要求。为此,借助变化率特征重新构建均方根误差变化量和平滑度变化量两个指标,利用熵权法定权将归一化后的两个指标线性组合,所得到的新指标即为复合评价指标。该方法借助指标的变化率随分解层数的增加表现出明显的收敛特性来确定去噪最优分解层数。实验表明,该方法能够在真值未知的情况下准确地指导小波分解,确定去噪最优分解层数,从而达到最优去噪效果。     

基于灯光数据的中国县域城镇建设用地产出效率时空演变特征

本文以灯光密度表征建设用地产出效率,采取KDE、ESDA、SDE等方法对中国县域尺度2000-2015年建设用地产出效率的总体特征、时空演变以及方向分布进行分析,研究发现：① 夜间灯光总亮度与建设用地出产出存在较强的相关关系,说明可用灯光总亮度表征建设用地产出,以灯光密度反映建设用地产出效率具有一定的科学性。② 建设用地产出效率东高西低,持续上升;增长速度西高东低,中部居中,但区域间年均增长率最大相差0.56%,整体较为均衡。③ 虽然建设用地产出效率由2000年的0.008单位灯光/km²持续上升至2015年的0.025单位灯光/km²,但其核密度曲线始终处于中低水平且右侧区间不断扩大,说明中国建设用地产出效率总体水平较低,呈现出中低水平俱乐部收敛的特征。④ 建设用地产出效率的全局 Moran's I指数都大于0,建设用地产出效率存在正向空间分布特征,且其局部空间格局变化较小,存在稳中有动,强中有弱,弱中有强的特点。⑤ 方向分布上,建设用地产出效率的方位角始终在72.420^o与81.066^o之间,说明东北-西南方向为建设用地产出效率的主要方向,且标准差椭圆的主轴与辅轴标准差都有所增加,说明在建设用地产出效率的主要方向与次要方向上都发生了分散现象。     

Seismogenic Structures of the 2006 ML4.0 Dangan Island Earthquake Offshore Hong Kong

The northern margin of the South China Sea, as a typical extensional continental margin, has relatively strong intraplate seismicity. Compared with the active zones of Nanao Island, Yangjiang, and Heyuan, seismicity in the Pearl River Estuary is relatively low. However, a ML4.0 earthquake in 2006 occurred near Dangan Island(DI) offshore Hong Kong, and this site was adjacent to the source of the historical M5.8 earthquake in 1874. To reveal the seismogenic mechanism of intraplate earthquakes in DI, we systematically analyzed the structural characteristics in the source area of the 2006 DI earthquake using integrated 24-channel seismic profiles, onshore–offshore wide-angle seismic tomography, and natural earthquake parameters. We ascertained the locations of NW-and NE-trending faults in the DI sea and found that the NE-trending DI fault mainly dipped southeast at a high angle and cut through the crust with an obvious low-velocity anomaly. The NW-trending fault dipped southwest with a similar high angle. The 2006 DI earthquake was adjacent to the intersection of the NE-and NW-trending faults, which suggested that the intersection of the two faults with different strikes could provide a favorable condition for the generation and triggering of intraplate earthquakes. Crustal velocity model showed that the high-velocity anomaly was imaged in the west of DI, but a distinct entity with low-velocity anomaly in the upper crust and high-velocity anomaly in the lower crust was found in the south of DI. Both the 1874 and 2006 DI earthquakes occurred along the edge of the distinct entity. Two vertical cross-sections nearly perpendicular to the strikes of the intersecting faults revealed good spatial correlations between the 2006 DI earthquake and the low to high speed transition in the distinct entity. This result indicated that the transitional zone might be a weakly structural body that can store strain energy and release it as a brittle failure, resulting in an earthquake-prone area.     

Spatial Variations of b-Values in the Coastal Area of Guangdong

We used earthquake catalogs recorded by Guangdong Seismological Network from 2008 to 2014 to resolve the spatial variations of b-values in the coastal area of Guangdong, particularly in three key research areas(Yangjiang, Heyuan, and offshore Nanao Island) with strong seismicity. Our results revealed that b-values exhibited significant spatial variations, and zones with low b-values could indicate the most likely seismogenic area of large earthquakes. We observed three clear low b-value patches in the offshore Nanao Island. We found a distinct high b-value peak at the depth of 11 km and two minimum peaks at about 14 and 7–8 km in the Yangjiang area. The overall b-values generally decrease with depth in the Heyuan area. The spatial variations of b-values reflect tectonic anomalies; that is, the ‘low-high-low' distribution of b-values in the offshore Nanao Island and the Yangjiang area may indicate the anomaly of the crustal structure with a weak layer. The b-values of reservoir-induced seismicity are obviously lower than that induced by tectonism. This finding indicates that the reservoir area is generally at high stress state under the condition of high pore pressure. We inferred that large earthquakes might be prone to occur at 10–12 km depth in the offshore Nanao Island, at 12–15 km depth in the Yangjiang area, and at the lower part of the seismic activity zone in the Heyuan area. Moreover, the upstream area of the Xinfengjiang reservoir is the most likely area of future large earthquakes in the Heyuan area.