Neoarchean Magmatic Events in the Western Songnen Massif,Central Asian Orogenic Belt: Timing and Tectonic Significance

Whether a Neoarchean basement existing in the Songnen massif is currently debated. Identification of Archean magmatism from the Songnen Massif is helpful to resolve this issue. Here, we report newly discovered Neoarchean Shanquan pluton in the Western Songnen Massif. These Neoarchean Shanquan pluton are mainly composed of granites that are exposed near the town of Shanquan in Heilongjiang Province. LA-ICP-MS zircon U-Pb dating reveals that the sample 2015TW1 has an upper intercept age of 2801 ± ...     

Temporal stress variations along a seismogenic megasplay fault in the subduction zone: An example from the Nobeoka Thrust,southwestern Japan

The Nobeoka Thrust, an ancient megasplay fault in the Shimanto Belt, southwestern Japan, contains fault rocks from the seismogenic zone, providing an accessible analog of active megasplay faults in deep subduction settings. In this study, the paleostress along the Nobeoka Thrust was analyzed using multiple inversion techniques, including k‐means clustering of fault datasets acquired from drillcores that intersected the thrust. The six resultant stress orientation clusters can be divided into two general groups: stress solutions with north–south‐trending σ₁ axes, and those with east–west‐trending σ₁ axes. These groups are characterized by the temporal changes for the orientations of the σ₁ and σ₃ principal stress axes that involve alternation between horizontal and vertical. The findings are probably due to a change in stress state before and after earthquakes that occurred on the fault; similar changes have been observed in active tectonic settings, such as the 2011 Tohoku‐Oki earthquake (Japan).     

Tectonic incorporation of the upper part of oceanic crust to overriding plate of a convergent margin: An example from the Cretaceous–early Tertiary Mugi Mélange, the Shimanto Belt, Japan

A tectonic mélange exposed on land is examined to reveal relationships between mélange formation, underplating, and deformation mechanisms, focusing on the deformation of basaltic rocks. The studied Mugi Mélange of the Shimanto Belt is composed of a shale matrix surrounding various blocks of sandstone, pelagic sediments, and basalts. The mélange was formed during Late Cretaceous to early Tertiary times in a subduction zone under P–T conditions of 150–200 °C and 6–7 km depth as estimated from vitrinite reflectance and quartz veins fluid inclusions. The mélange represents a range of deformation mechanisms; pressure solution with micro-scale cataclasis in the shale matrix, brittle tension cracking in the blocks, and ubiquitous strong cataclasis in the basal portion of basaltic layers. The cataclastic deformation in the basalts suggests a breakage of a topographic high in the seismogenic depth.     

长周期波浪激发矩形港池多模态共振研究

长和宽接近的矩形港池存在横向、纵向及横纵向混合共振模态。采用基于混合有限元的椭圆型缓坡方程数值模型模拟不同波浪入射角的低频波浪激发矩形港池的多模态共振,并分析不同平面布置形式的矩形港池模态响应特性。结果表明,斜向波浪会激发港池的横向共振模态,其放大因子受入射角度影响较大,而纵向共振模态的放大因子受入射角度影响较小。口门宽度对港池的共振模态个数与放大因子均有影响,具体为:随着口门宽度增加,各阶模态放大因子减小。口门位置对纯横向以及纯纵向共振的振荡模式有显著影响,而对横向纵向混合模态影响较小。各阶模态放大因子的大小和波节线与波腹线与口门的相对位置密切相关。     

Petrological model of the northern Izu–Bonin–Mariana arc crust: constraints from high-pressure measurements of elastic wave velocities of the Tanzawa plutonic rocks, central Japan

Ultrasonic compressional wave velocities (Vp) and shear wave velocities (Vs) were measured with varying pressure up to 1.0 GPa in a temperature range from 25 to 400 °C for a suite of tonalitic–gabbroic rocks of the Miocene Tanzawa plutonic complex, central Japan, which has been interpreted as uplifted and exposed deep crust of the northern Izu–Bonin–Mariana (IBM) arc. The Vp values of the tonalitic–gabbroic rocks increase rapidly at low pressures from 0.1 to 0.4 GPa, and then become nearly constant at higher pressures above 0.4 GPa. The Vp values at 1.0 GPa and 25 °C are 6.3–6.6 km/s for tonalites (56.4–71.1 wt.% SiO₂), 6.8 km/s for a quartz gabbro (53.8 wt.% SiO₂), and 7.1–7.3 km/s for a hornblende gabbro (43.2–47.7 wt.% SiO₂). Combining the present data with the P wave velocity profile of the northern IBM arc, we infer that 6-km-thick tonalitic crust exists at mid-crustal depth (6.1–6.3 km/s Vp) overlying 2-km-thick hornblende gabbroic crust (6.8 km/s Vp). Our model shows large differences in acoustic impedance between the tonalite and hornblende gabbro layers, being consistent with the strong reflector observed at 12-km-depth in the IBM arc. The measured Vp of Tanzawa hornblende-bearing gabbroic rocks (7.1–7.3 km/s) is significantly lower than that Vp modeled for the lowermost crustal layer of the northern IBM arc (7.3–7.7 km/s at 15–22 km depth). We propose that the IBM arc consists of a thick tonalitic middle crust and a mafic lower crust.     

Viral diseases of olive flounder in Korean hatcheries

In order to elucidate the state of diseases, especially viral diseases, and to prevent viral diseases from occurring in olive flounder hatcheries, a range of studies, including epidemiological study, were performed from 1997 to 2003. The location of the hatcheries investigated includes several representative sites in the east （Kangnung, Uljin, Pohang, Yangsan, Ulsan, Pusan）, south （Wando, Changheung, Goheung, Yeosu, Namhae, Tongyeong, Geoje, Jeju） and west （Seosan, Kunsan, Gochang, Yeongkwang, Mokpo, Chindo） costal areas of the Korea Peninsula. A total of 2000 cases have been examined in 7 years, in which mortality caused by viral agents accounts for 22%, or 446 cases. Mortalities associated with viral infection considerably increased from 14% in 1997 to 27% in 2003. A variety of viral diseases were observed, and the occurrences of viral epidermal hyperplasia, viral ascites and viral deformity, viral nervous necrosis, and hirame rhabdoviral disease are 14%, 51%, 25%, and 8% respectively. By investigating the viral infection of broodstock flounder, the infection rate of marine birnavirus （MABV） in hatcheries was identified to be approximately 30%, therefore, it is highly necessary to acquire and keep non-infected broodstock fishes.     

莱河矿(Fe0.52+Fe1.03+SiO4)的超结构

莱河矿于1976年在中国辽宁省的磁铁矿床中首次被发现,许多人对它进行过研究。该矿物为黑色、不透明,化学式为Fe_0.58²⁺Fe_1.0³⁺Mg_0.03Si_0.96O₄,虽然它的晶体结构近似于橄榄石,但已确定为单斜晶系,空间群为P2₁/b。本文作者利用X射线、电子探针、高分解能透过电子显微镜对该矿物进行了系统的研究,发现它具有假双晶、超结构和显微条纹结构。     

城市地下空间资源评价三维建模方法研究与实践:以上海市为例

城市地下空间开发利用是智慧城市发展的重要组成部分.构建城市地下空间三维地质模型和属性模型,能够立体直观地展示地下构筑物、河道、水系等,进一步与三维模型融合后,可以更好地展示地下空间资源质量.本文以上海市中心城区地下空间资源评价为示范,设计了三维地质结构和属性模型一体化建模方法,构建了上海市中心城区地下空间三维地质模型,...     

GMS卫星遥感资料监测暴雨技术

利用时空分辨率较高的GMS－5红外、可见光两通道1：1原始图像资料，结合常规雨量观测资料，通过对逐时降水率、日降水量的估计，讨论了卫星遥感监测暴雨的技术方法，建立了山东省暴雨遥感监测模型。实例分析表明，暴雨监测图像产品直观清晰，能较准确地监测暴雨发生的区域和面积，实际应用取得较好的效果。     

COVID-19疫情时空聚集性特征及影响因素分析——以重庆市为例

新型冠状病毒肺炎(COVID-19)在城市内部的病例时空聚集性特征及影响因素对于疫情防控具有重要参考价值。论文以重庆市为例,收集2020年1月21日—2月24日的458例COVID-19确诊病例数据,结合手机信令数据与空间环境数据,采用空间聚集性分析、因子分析与回归分析等方法,探究重庆市新冠疫情在街道尺度上的时空聚集性特征,并分析其影响因素。结果表明：① 时间上,确诊病例前期增长较快,以外地输入为主,后期逐渐趋缓,以本地传播(包括街道间传播、街道内传播、家庭内传播)为主,其中家庭内传播占比最大(23%);② 空间上,病例呈现显著的聚集特征,且聚集性逐渐增强,热点街道分布于重庆市西部、东北部;分类型来看,本地病例热点街道集中于人口密度较大、经济发展更好的西北部、西南部,外地输入病例热点街道集中于地理邻近湖北省的中部、东北部;③ 所有病例密度、本地病例密度、外地输入病例密度与因子分析所得4个因子(即城市交通因子、街道间活动因子、生活服务因子、居民分布因子)的回归结果显示,交通设施水平与病例密度存在密切关联,商店超市餐饮等生活服务地点与病毒传播显著相关,街道间活动是发生聚集性疫情的重要因素,而外地输入型病例多出现于人口密集区域。疫情防控中应根据不同区域疫情传播模式差异实施针对性措施,例如在重庆市中部、东北部关注外地输入防控,西北部、西南部以本地传播防控为重点;同时,应加强城市内部交通与街道居民接触密集区域的防控措施,有效防止疫情反弹。