新疆及邻区体波震级初步分析研究

依据《地震震级的规定（GB 17740—2017）》,分析了2009—2017年新疆地震台网所记录的新疆及邻区476次中深源地震事件,测定了13601个m_b（短周期体波震级）和12035个m_B（BB）（宽频带体波震级）的数据样本,回归分析m_b和m_B（BB）得到回归方程及量规函数,结果显示m_b和m_B（BB）相关系数为0.966,表明两者显著相关。因此,建议对于中强型中深源地震可以直接从原始速度型宽频带数字地震记录上测定长周期体波震级m_B（BB）,提高地震速报测定的速度和精度。通过震级偏差统计和台站场地响应计算,分析新疆地震台网中的XKR、HTA、ATS和KSZ等地震台站震级偏差较大的原因为砂岩、灰岩、砂土层等类型的台基放大了场地响应,说明台基类型对体波震级偏差的影响较大。与NEIC测定的体波震级对比时,发现新疆地震台网测定体波震级平均偏大0.42级,且偏差随着震源深度的增加有增大的趋势。     

2013—2017年夏季东北冷涡下东北地区MCS的统计特征

利用2013—2017年6—8月FY-2E和FY-2G地球静止卫星相当黑体温度（Black Body Temperature,TBB）资料、NCEP/NCAR再分析资料,对我国夏季东北冷涡下东北地区MCS的分布和活动特征进行了统计分析,结果表明：（1） MCS的活动具有明显的月际变化和日变化特征,6月对流活动最活跃。MCS的主要移向是东、东北和东南,平均移动距离3.99个经纬距。（2） MCS成熟时刻的面积、偏心率和生命史均小于江淮地区以及中国中东部,云顶高度低于江淮地区,整个生命史表现出发展快消亡慢的特征,与江淮地区相反。（3）基于MCS的定义得到的Z标准,对2016—2017年的MCS作了统计分析并与J标准统计得到的MCS进行对比,得出,两种定义下的MCS环境场特征基本一致,主要表现为MCS多生成于500 hPa槽前和槽后,对流层高层MCS位于双急流之间靠近北支急流的辐散区,南侧急流高度在200 hPa,北侧的急流高度在250 hPa。低层,位于低空急流左侧,低涡南侧、东南侧,有较强的水汽和动量输送。槽前生成的MCS南侧中层存在垂直反环流向MCS输送干暖空气与位涡,槽后生成的MCS两侧均有大值位涡向其输送,同时北侧冷干空气的输送使锋区及上升运动加强,更有利于MCS的形成。（4）两种标准下的MCS造成的降水明显不同,在统计强降水方面Z标准要优于J标准。由于Z标准空间与时间尺度较小,统计得到的MCS较多;但同时会遗漏部分相对弱的MCS。     

河西干旱区短时强降水过程的中尺度分析

运用中尺度天气分析技术,对河西西部干旱区3次短时强降水过程从高空、地面的影响系统、水汽条件、抬升条件、不稳定条件、高低层风场配置等方面进行了对比分析,找出了3次过程的相似点与不同之处,结果表明:500 hPa新疆有低压槽东移,低槽前部甘肃河东到张掖为高压脊或者歪脖子高压,青海高原有低涡或者切变线,相应的低层也为低槽、切变线或者低涡,地面有冷锋、辐合线配合的环流形势是河西西部短时强降水产生的关键,高空急流(200 hPa)或者高空显著流线入口区右侧、地面露点温度Td>10℃的高湿区、低层绝对湿度比湿>6 g/kg,中层500 hPa处在显著湿区、700 hPa假相当位温高能舌、K指数>30℃,CAPE值也明显增大为产生短时强降水提供了有利条件,最后建立了河西西部干旱区短时强降水中尺度天气分析概念模型。     

Strongly peraluminous granites of Mesozoic in Eastern Nanling Range,southern China: Petrogenesis and implications for tectonics

The strongly peraluminous granites (SPGs) of Eastern Nanling Range (ENR) are a characteristic of all bearing highly aluminous minerals, such as muscovite±AI-rich biotite±tourmaline±garnet, and lack of cordierite. In respect of petrography, geochemistry, Nd isotope, and single grain zircon U-Pb dating, the representative granite bodies of them are studied. The research shows that these granites were emplaced in two stages, namely 228-225 Ma BP and J2-3 159-156 Ma BP, belonging to Indosinian and early Yanshanian periods, respectively, and they have low εNd(t) values (-10.6--11.1), high A/CNK, Rb/Sr ratios and tDM values (1887-1817 Ma), and REE's tetrad effect (TE1,3=1.13-1.34). In comparison with related geology, petrology and chronology of granites in adjacent regions, it is suggested that Indosinian SPGs of ENR formed in the circumstance of post-collisional extension 20 Ma after the major collision of Indosinian Movement (258-243 Ma BP) in Indo-China Peninsula, and early Yanshanian SPGs formed in the     

U–Pb and Hf-isotope analysis of zircons in mafic xenoliths from Fuxian kimberlites: evolution of the lower crust beneath the North China craton

Mafic xenoliths from the Paleozoic Fuxian kimberlites in the North China craton include garnet granulite, and minor pyroxene amphibolite, metagabbro, anorthosite and pyroxenite. The formation conditions of the amphibolites are estimated at 745–820 °C and 7.6–8.8 Kb (25–30 km); the granulites probably are derived from greater depths in the lower crust. LAM-ICPMS U–Pb dating of zircons from four granulites reveals multiple age populations, recording episodes of magmatic intrusion and metamorphic recrystallisation. Concordant ages and upper intercept ages, interpreted as minimum estimates for the time of magmatic crystallisation, range from 2,620 to 2,430 Ma in three granulites, two amphibolites and two metagabbros. Lower intercept ages, represented by near-concordant zircons, are interpreted as reflecting metamorphic recrystallisation, and range from 1,927 to 1,852 Ma. One granulite contains two metamorphic zircon populations, dated at 1,927±55 Ma and 600–700 Ma. Separated minerals from one granulite and one amphibolite yield Sm–Nd isochron ages of 1,619±48 Ma (¹⁴³Nd/¹⁴⁴Nd)i=0.51078), and 1,716±120 Ma (¹⁴³Nd/¹⁴⁴Nd)i=0.51006), respectively. These ages are interpreted as recording cooling following metamorphic resetting; model ages for both samples are in the range 2.40–2.66 Ga. LAM-MC-ICPMS analyses of zircon show a range in ¹⁷⁶Hf/¹⁷⁷Hf from 0.28116 to 0.28214, corresponding to a range of _Hf from –34 to +12. The relationships between ²⁰⁷Pb/²⁰⁶Pb age and _Hf show that: (1) the granulites, amphibolites and metagabbro were derived from a depleted mantle source at 2.6–2.75 Ga; (2) zircons in most samples underwent recrystallisation and Pb loss for 100–200 Ma after magmatic crystallisation, consistent with a residence in the lower crust; (3) metamorphic zircons in several samples represent new zircon growth, incorporating Hf liberated from breakdown of silicates with high Lu/Hf; (4) in other samples metamorphic and magmatic zircons have identical ¹⁷⁶Hf/¹⁷⁷Hf, and the younger ages reflect complete resetting of U–Pb systems in older zircons. The Fuxian mafic xenoliths are interpreted as the products of basaltic underplating, derived from a depleted mantle source in Neoarchean time, an important period of continental growth in the North China craton. Paleoproterozoic metamorphic ages indicate an important tectonic thermal event in the lower crust at 1.8–1.9 Ga, corresponding to the timing of collision between the Eastern and Western Blocks that led to the final assembly of the North China craton. The growth of metamorphic zircon at 600–700 Ma may record an asthenospheric upwelling in Neoproterozoic time, related to uplift and a regional disconformity in the North China craton.     

“7·22”云南盐津地震房屋震害分析

本文根据地震现场的考查情况,介绍了2006年7月22日云南盐津5.1级地震的灾害概况,归纳和分析了灾区生土墙结构、石结构、钢筋混凝土框架结构和木构架结构房屋的震害特征及其破坏原因,并对我国村镇房屋的防震减灾研究提出了若干建议。     

2008年北京奥运会开幕式化学危害预测数值模拟

针对2008年北京奥运会安保,建立了一个复杂的系统,包括两个气象预报模式MM5和RAMS6.0以及一个复杂地形上有毒云团的扩散模式CDM。开发了MM5和RAMS6.0接口模块,发展了基于RAMS6.0气象场预报结果的CDM,实现了对未来36h内的精细气象场和扩散场进行模拟,气象场预报的分辨率为500～1000m,扩散场的分辨率可达到50～200m。基于T213数据,应用MM5进行了水平分辨率为3km的气象场初步预报,将该预报结果转化为RAMS6.0识别的数据格式,应用RAMS6.0对气象场进行分辨率为500～1000m的精细预报,得出北京奥运会期间的风场与湍流量的预报结果。基于该气象场,根据想定,应用CDM对北京奥运会国家体育场"鸟巢"附近发生化学事件时进行了模拟研究,得出危害范围、危害等级、危害开始时间、危害持续时间等时空分布,为奥运会开幕式化学危害应急提供技术支持。     

临夏黄土记录的26万年来季风快速变化

黄土高原西部高分辨率黄土序列开展的多代用指标研究,有助于揭示轨道-亚轨道尺度上东亚冬、夏季风的变化特征及动力机制。但针对同一地质记录提取冬、夏季风多代用指标进行对比和敏感性分析的工作尚不多见,因此制约了对季风快速变化特征和机理的理解。本文利用甘肃临夏85 m黄土岩芯开展高分辨率的粒度、磁化率和元素扫描分析,发现在轨道尺度上粒度和Zr/Rb比值显示的大幅冰期-间冰期波动与深海氧同位素记录有很好的对应关系,表明东亚冬季风的波动响应于北半球高纬冰量的变化。但在千年尺度上,粒度能更敏感地响应冬季风的快速变化;Rb/Sr比值和磁化率均能很好记录轨道尺度上的东亚夏季风波动,但在亚轨道尺度上Rb/Sr的敏感性明显高于磁化率。粒度、Zr/Rb和Rb/Sr所指示的东亚季风快速变化表现出较强的岁差信号,与石笋和北纬65°夏季太阳辐射有较好的对应关系,表明东亚季风变化也受到岁差直接驱动的夏季太阳辐射变的控制。在最后两个冰期-间冰期旋回中(即末期冰期旋回和倒数第二次冰期旋回)Rb/Sr及Zr/Rb比值和粒度记录分别可以辨别出与石笋相同数量级的变暖事件,但粒度记录的暖事件明显要多于Rb/Sr及Zr/Rb比值,且这些暖事件并不能一一对应。粒度及元素比值记录显著变冷的千年尺度的Heinrich(H)事件与石笋记录的夏季风明显减弱的事件有很好的对应关系,但其发生频率明显高于海洋记录。这些指标记录的千年尺度上波动信号的不一致性主要归因指标对不同气候要素敏感性的差异。未来需要进一步开展高分辨率多代用指标敏感性分析,选取对季风快速变化的敏感指标,有助于我们理解季风快速变化的特征(如周期和幅度等)和分析季风快速变化的时空差异性。     

区位因素影响下高铁站区产业结构特征——基于POI数据的实证分析

高铁站被视为拉动城市经济增长的新型空间,研究其周边产业结构对指导高铁站区的开发具有重要意义。本文选取了全国范围内9个不同区位、不同等级的高铁站为研究对象,以高铁站周边3000 m范围内10类产业的POI信息作为研究数据,通过Ripley's K函数、核密度估计和产业指数等方法探索不同区位下高铁站区的产业结构特征。研究发现：① 当高铁站的等级规模相同时,高铁站距离城市中心越远,站区内产业POI总数一般就越少。其中,购物服务、餐饮服务、生活服务和公司企业4类产业的POI数量显著高于其他产业。② 所有高铁站区的产业在1500 m的观测距离内均呈现出显著的集聚分布特征。其中,中心站产业集聚程度的变化较为平缓,城区站产业集聚程度最高,变化幅度也更大,而新城站的规律特征不明显。③ 中心站的产业集聚区域主要分布在高铁站周边0~2500 m的范围内,城区站的产业集聚现象在500~2500 m范围内较为明显,而新城站的产业集聚区域则集中在0~1500 m、2000~3000 m的范围以内。④ 基本服务产业和衍生服务产业主要集中于内圈层和中间圈层,相关服务产业则主要分布在中间圈层和外圈层,各圈层内产业复合特征明显,且高铁站越远离城市中心,其对产业的辐射作用越弱,产业衰减趋势也越明显。基于以上结论,本文认为未来高铁站区的产业开发更应关注土地开发集约化和产业发展复合化。     

Analysis of the Spatio-temporal Changes in Acid Rain and Their Causes in China (1998-2018)

With the rapid development of the economy, acid rain has become one of the major environmental problems that endanger human health. Being the largest developing country, the environmental problems caused by acid rain are of increasing concern with the rapid industrialization and urbanization in China. Recently, many researchers have focused on acid rain. To better understand the temporal and spatial dynamics of acid rain in China, the monitoring data on acid rain from 1998 to 2018 were studied using ArcGIS 10.2. The results show that the proportion of acid rain cities, the frequency, and the area of acid rain were decreasing, however, the situation still remains serious. Overall, the chemical type of acid rain was mainly sulfuric acid rain. However, the concentration ratio of SO₄ ^2-/NO₃ ^- decreased by 81.90% in 2018 compared with 1998, and presented a decreasing trend, which indicates that the contribution of nitrate to precipitation acidity has been increasing year by year. This research will help us to understand the distribution characteristics and causes of acid rain in China, and it may provide an effective reference for the prevention and control of acid rain in China.