Mooring observed mode-2 internal solitary waves in the northern South China Sea

The mode-2 internal solitary waves (ISWs) generated by mode-2 internal tide (IT) are identified by mooring observations in the northern South China Sea (SCS) from 2016 to 2017. Two mode-2 ISWs with a re-appearance period of 24.9 h observed on 29 and 30 July 2016 are characterized by type-b ISWs. They occurred when the isotherms compressed obviously in the vertical direction. Modal decomposition of IT horizontal currents shows that the vertical compression of the isotherms is mainly caused by diurnal mode-2 IT. The analysis of the role of the density stratification reveals that a deeper and thinner pycnocline is favorable for generation of mode-2 ISWs rather than pycnocline intensity. By comparing the mode-2 nonlinear, dispersion coefficients and the Ursell numbers calculated based on the stratification associated with different kinds of ITs with the observation results, it is shown that the diurnal mode-2 IT plays a crucial role in the generation of the mode-2 ISWs. When the diurnal mode-2 IT interacts with the semidiurnal IT and causes a deeper and thinner pycnocline, the mode-2 ISWs are easily excited.     

一种控制陆相地层横向变化的方法——以民和盆地早白垩世地层为例

陆相地层侧向加积作用广泛发育 ,导致岩性、岩相横向多变。如何控制陆相地层横向不稳定性 ,是盆地分析的难点。利用高分辨率事件沉积作用 ,结合岩性变化带 ,可以在盆地确定等时地层单元 ,在横向地层变化研究中提高精度 ,是控制陆相地层横向变化的有效方法     

Tectonic evolution of the South Tianshan orogen and adjacent regions,NW China: geochemical and age constraints of granitoid rocks

Geochemical and geochronological evidence was obtained from granitoids of the South Tianshan orogen and adjacent regions, which consist of three individual tectonic domains, the Kazakhstan–Yili plate, the Central Tianshan Terrane and the Tarim plate from north to south. The Central Tianshan Terrane is structurally bounded by the Early Paleozoic ‘Nikolaev Line–North Nalati Fault’ and Late Paleozoic ‘Atbashy–Inyl’chek–South Nalati–Qawabulak Fault’ zones against the Kazakhstan–Yili and Tarim plates, respectively. The meta-aluminous to weakly peraluminous granitic rocks, which are exposed along the Kekesu River and the Bikai River across the Central Tianshan Terrane, have a tholeiitic, calc-alkaline or high-potassium calc-alkaline composition (I-type). Geochemical trace element characteristics and the Y versus Rb–Nb or Y versus Nb discrimination diagrams favor a continental arc setting for these granitoid rocks. SHRIMP U–Pb and LA-ICP-MS U–Pb zircon age data indicate that the magmatism started at about 480 Ma, continued from 460 to 330 Ma and ended at about 275 Ma. The earlier magmatism (>470 Ma) is considered to be the result of a simultaneous southward and northward subduction of the Terskey Ocean beneath the northern margin of the Tarim plate and the Kazakhstan–Yili plate, respectively. The later magmatism (460–330 Ma) is related to the northward subduction of the South Tianshan Ocean beneath the southern margin of the Kazakhstan–Yili–Central Tianshan plate. The dataset presented here in conjunction with previously published data support a Late Paleozoic tectonic evolution of the South Tianshan orogen, not a Triassic one, as recently suggested by SHRIMP U–Pb zircon dating for eclogites.     

浅谈灌注桩抗拔试验中桩身裂缝防治措施

针对灌注桩抗拔试验过程中出现裂缝的问题,以山东某新建换流站试桩工程为例,研究了灌注桩裂缝产生的过程、裂缝缝宽的变化规律以及裂缝的分布范围,在此基础上分析了裂缝产生的原因,最后提出了相应的防治措施,以供类似工程进行借鉴。     

二度体重、磁异常频谱与三度体重、磁异常频谱关系的理论问题

设F（x-ξ,y,z,η,ζ,α,…）为一在x方向无限薄的层的异常,若物体的异常可表示为: T（x,y）=integral from n=a to （a+2c）（F（x-ξ,y,z,η,ζ,α,…））dξ T（y）=integral from n=-∞ to ∞（F（x-ξ,y,z,η,ζ,α,…））dξ 则有 式中T（v）和T（u,v）分别为T（y）和T（x,y）的频谱,2c是物体在x方向的宽度,（x,y,z）和（ξ,η,ζ）分别为观测点和物体上任一点的坐标。 如果2c=dξ,则物体即为薄层本身;如果2c=dξ,薄层的面积无限缩小,则物体即为一质点;如果2c=dξ,薄层只有长度而无宽度,则物体即为一曲线。 对于形状复杂的物体,可以将物体分成若干简单而又符合所述条件的物体元,而有式中2cm为第m个物体元在x方向的宽度,Tm（v）为第m个物体元当其沿x方向的长度为无限长时的异常的频谱。     

水生生物监测质量保证、质量控制与标准化:动态与展望

水生生物监测是流域水生态状况评价的重要基础,监测数据的准确性和可靠性直接影响水生态环境质量评价与流域水生态管理成效。目前我国水生生物监测质量保证和质量控制体系尚处于持续完善的阶段,关键环节的控制要求和质控目标等亟待明确和细化。本文总结了欧美发达国家水生生物监测质量保证与质量控制体系建设中的经验,通过梳理我国水生生物监测工作基础与进展,较为系统地提出了适合我国现状的水生生物监测质量保证与质量控制体系标准化建设对策建议,包括实验室内部和外部质量保证与质量控制、水生生物监测质控数据库、人工智能识别和环境DNA新技术质控要点等标准化建议,为实现水生生物监测业务化运行,准确评估我国流域水生态质量状况的变化提供技术支撑。     

Rupture process of the M_s 7.0 Lushan earthquake, 2013

On April 20, 2013 at 8:02 am, a magnitude 7.0 earthquake occurred in Lushan County, Sichuan Province, China, which induces massive landslides, causes great losses to life and property. Based on the locations of aftershocks provided by the China Earthquake Network Center and the characteristic of Longmenshan active faults system, combined with the current preliminary focal mechanism solution, the fault rupture direction is determined. With the finite fault inversion method, we invert the rupture process of the Lushan M s 7.0 earthquake by teleseismic waveforms data. The inversion results indicate that the main shock is dominated by thrust fault component and the rupture initiated at depth of 15 km, and most of slip ruptured around the hypocenter with the peak slip of about 1.5 m. Most of rupture slips released at the first 20 s and the main rupture occurred at the first 10 s after the onsets of the mainshock. Most of seismic energy released near the hypocenter with a length of 28 km, especially on both sides of the hypocenter with the range of 20 km, and the seismic energy released relatively smaller in other areas. There is a large area with weak slip between the main rupture and another two asperities on both sides of the hypocenter; it may imply that the accumulated strain on the rupture fault has not been completely released. Therefore, there is a significant possibility of having strong aftershocks in the areas where energy is not fully released. This is also the main reason why there are a lot of moderate to strong aftershocks in the Lushan aftershock sequence. In addition, there is an earthquake vacant zone with a length of about 50 km between the Wenchuan M w 7.9 earthquake and this event, which is of high earthquake risk and is deserved to be paid close attention to.     

滇中砂岩铜矿成矿作用和成矿模式

分析了滇中砂岩铜矿的成矿作用过程，砂岩铜矿的形成经历了沉积作用期、成岩作用期和后生作用期，矿床形成后又经历了构造改造期及表生改造期，其中成岩作用期是主要的成矿时期，在上述分析的基础上，建立了该类型矿床的成矿模式。     

川西中泥盆统观雾山组白云岩储层储集空间类型、成因及演化

川西地区观雾山组白云岩储层储集空间主要为孔洞和裂缝两类。为弄清观雾山组白云岩储层孔洞成因、孔洞充填期次及演化,首先,通过对孔洞型白云岩储层发育规律与沉积相、层序关系的分析,结合第一期白云石胶结物形成与围岩白云石化的先后顺序,认为川西地区观雾山组白云岩储层孔洞为相控准同生岩溶形成;针对孔洞内不同期次白云石和方解石胶结物的包裹体均一温度、碳氧同位素、激光原位U-Pb同位素定年、锶同位素、稀土元素等分析,认为孔洞内胶结物形成于封闭的成岩环境,成岩流体为受下伏碎屑岩地层水加入改造的中泥盆世海水。观雾山组白云岩储层储集空间经历了三个演化阶段:沉积期-白云石化之前的孔洞及裂缝形成阶段、白云石化期间的围岩白云石化及第一期白云石胶结物形成阶段和中—深埋藏成岩期的孔隙定型阶段,其中中—深埋藏阶段是孔隙减少的主要阶段,造成约25%的孔隙损失。