中国4个地点地基与卫星臭氧总量长期观测比较

对我国河北香河、云南昆明、青海瓦里关及黑龙江龙凤山地基观测臭氧总量与不同时期、不同卫星反演的产品差别特点进行比较,评估地基和卫星观测臭氧总量数据的质量信息以及近30年来我国不同区域臭氧总量的变化趋势特征。结果表明:4个站点的地基与卫星观测臭氧总量的绝对和相对差别分别为-5~10 DU和-5%~4%;日平均相对差别基本上呈现随机分布特征。TOMS算法反演的卫星臭氧总量与地基差别总体上要优于与DOAS算法反演的同期产品。地基与卫星臭氧总量差别呈明显的区域特点,可能反映了卫星反演计算中所需的臭氧、温度垂直分布等初始条件的纬度分布差异对卫星产品精度的影响。在过去30年,4个站点的臭氧总量在经历1993年前的显著降低后于1995—1996年逐渐回升,而瓦里关站在2001年前后的回升更为明显。     

L波段气象探测网运行监控系统设计

L波段气象探测网监控系统用来监视包括L波段探空设备与探空数据在内的全国高空气象探测网总体运行情况。基于L波段探空系统提供的监控信息与探空资料,结合业务运行经验与用户需求建立L波段高空气象探测网监控系统。运行结果表明:利用L波段高空监视系统,结合探空资料质量检查,能够及时发现探空系统存在的问题;高空监视系统有助于全面掌握全国探测网系统设备的运行状况,保障高空探测网稳定运行,提高气象探空数据质量,业务效果显著。但是在探空质量评估中也发现位势高度、温度以及风向与风速变化阈值存在控制过严的现象,需要加以改进,以避免虚警次数过多。     

Simultaneous optical and electrical observations on the initial processes of altitude-triggered negative lightning

Using a high-speed camera system and two electric field antenna systems, we have documented the initial processes of an altitude-triggered negative lightning (ATNL). The optical records clearly show that ATNL begins with the inception and propagation of an upward positive leader (UPL) and then a simultaneous propagation of UPL and downward negative leader (DNL), known as the bidirectional leader process, follows. Based on the optical records, it is inferred that (1) the triggering height is about 371 m; (2) the two-dimensional (2D) propagation speed of the UPL in its inception phase is about 3.8–5.5 × 10⁴ m s^− 1 during its propagation from about 393 to 452 m above the ground; (3) the grey levels of the DNL are about one order of magnitude higher than that of the UPL in their inception phase; (4) a discharge phenomenon propagating along the elevated triggering wire part of the lightning channel occurs after the mini-return stroke (MRS), with a 2D propagation speed of about 1.6–2.0 × 10⁵ m s^− 1. Combined with the simultaneous electric field change records, it is further inferred that (1) the UPL incepts about 932 μs earlier than the unstable DNL and about 4.1 ms earlier than the stable DNL; (2) the unstable DNL propagates downward intermittently three times with a time interval of about 1 ms, and each propagation contains a different number of steps with an average step length of about 7 m; (3) the stable DNL incepts at the tip of the unstable one, with a 2D propagation speed of about 1.9 × 10⁵ m s^− 1, an average step length of about 3 m, and a stepping time interval varying from 6 to 31 µs with a mean value of 15 µs.     

新疆谢米斯台地区中段火山岩岩石学、地球化学及其含矿性研究

新疆西准噶尔谢米斯台山地区位于西伯利亚板块与准噶尔板块之间的古生代萨吾尔—阿尔曼太复合岛弧内。该地区的火山岩以安山岩—英安岩—流纹岩组合为主,有少量的粗面岩产出。在地球化学特征上,火山岩SiO_2含量变化范围较大(53.91～75.71 wt%),K_2O/Na_2O比值为0.45～1.89,Al_2O_3含量较高(10.81～17.94 wt%),铁含量低(1.20～7.26 wt%),TiO_2含量低(0.19～1.78 wt%),大离子亲石元素及轻稀土元素富集,微量元素具岛弧火山岩特征;地球化学的特征以及在该地区发现的大量铜矿化,预示着该地区将是一个有利的成矿远景区。     

Eocene potassic and ultrapotassic volcanism in south Tibet: New constraints on mantle source characteristics and geodynamic processes

In the Yangbajing area, southern Tibet, several monogenic volcanoes were conformably superimposed on the Linzizong calc-alkaline volcanic successions. According to their petrologic and geochemical characteristics, these monogenic volcanoes are composed of three rock varieties: tephritic phonolitic plugs and shoshonitic and trachytic lavas. Their geochemical systematics reveals that low-pressure evolutionary processes in the large voluminous Linzizong calc-alkaline magmas were not responsible for the generation of these potassic–ultrapotassic rocks, but the significant change in petrologic and geochemical characteristics from the Linzizong calc-alkaline to potassic–ultrapotassic magma is likely accounted for the change of metasomatic agents in the southern Tibetan lithospheric mantle source during the Paleocene to Eocene. The tephritic phonolites containing both leucite and plagioclase show primary ultrapotassic character similar to that of Mediterranean plagioleucititic magmas. Radiogenic Sr increases with SiO₂ in the xenolith-bearing trachytes strongly suggesting significant crustal assimilation in the shoshonitic magmas. The Yangbajing ultrapotassic rocks have high K₂O and Al₂O₃, and show depletion of high field strength elements (HFSEs) with respect to large ion lithophile elements. In primitive mantle-normalized element diagrams, all samples are characterized by positive spikes at Th (U) and Pb with negative anomalies at Ba, Nb–Ta and Ti, reflecting the orogenic nature of the ultrapotassic rocks. They are characterized by highly radiogenic ⁸⁷Sr/⁸⁶Sr_(i) ratios (0.7061–0.7063) and unradiogenic ¹⁴³Nd/¹⁴⁴Nd_(i) (0.5125), and Pb isotopic compositions (²⁰⁶Pb/²⁰⁴Pb = 18.688–18.733, ²⁰⁷Pb/²⁰⁴Pb = 15.613–15.637, and ²⁰⁸Pb/²⁰⁴Pb = 38.861–38.930) similar to the global subducting sediment. Strong enrichment of incompatible trace elements and high Th fractionation from the other HFSEs (such as Nb and U) clearly indicate that the Th-enriched sedimentary component in a network veined mantle source was mainly introduced by sediment-derived melts. In addition, the ultrapotassic rocks have significant Ce (Ce/Ce* = 0.77–0.84) and Eu (Eu/Eu* = 0.72–0.75) anomalies, suggesting a subduction sediment input into the southern Tibetan lithospheric mantle source. In contrast, high U/Th (> 0.20) and Ba/Th (> 32) and low Th/La (< 0.3) in the shoshonites indicate that the Eocene potassic magma originated from partial melting of the surrounding peridotite mantle pervasively affected by slab-related fluid addition from the dehydration of either the subducting oceanic crust or the sediment. Thus, at least two different subduction-related metasomatic agents re-fertilized the upper mantle. According to the radiometric ages and spatial distribution, the Gangdese magmatic association shows a temporal succession from the Linzizong calc-alkaline to ultrapotassic magmas. This indicates a late arrival of recycled sediments within the Tibetan lithospheric mantle wedge. The most diagnostic signatures for the involvement of continent-derived materials are the super-chondritic Zr/Hf (45.5–49.2) and elevated Hf/Sm values (0.81–0.91) in the ultrapotassic rocks. Therefore, the occurrence of orogenic magmatism in the Gangdese belt likely represents the volcanic expression of the onset of the India–Asia collision, preceding the 10 Ma Neo-Tethyan slab break-off process at 42–40 Ma. The absence of residual garnet in the mantle source for the ultrapotassic volcanism seems to imply that the southern Tibetan lithosphere was not been remarkably thickened until the Eocene (～ 50 Ma).     

地下水安全开采量的概念与评价方法研究

本文回顾了地下水安全开采量概念的产生与发展过程,综述了可持续开采量、允许开采量和安全开采量的内涵与差异,在此基础上,提出满足地下水的资源供给、生态环境维持、地质环境稳定和可持续开发利用能力4个功能条件下的地下水安全开采量概念.将安全开采量的评价方法分为单一约束型和耦合约束型两大类,提出一种基于水均衡和地下水动力学相结合的评价方法,并对安全开采量研究趋势进行了展望,为地下水的安全开采方案研究与动态管理提供技术支撑.     

WD+MS systems as the progenitor of SNe Ia

The single-degenerate (SD) channel for the progenitors of type Ia supernovae (SNe Ia) is one of the most popular channels, in which a carbon–oxygen white dwarf (CO WD) accretes hydrogen-rich material from its companion, increases its mass to the Chandrasekhar mass limit, and then explodes as a SN Ia. We show the initial and final parameter space for SNe Ia in a ( $\log P^{\mathrm{i}},M_{2}^{\mathrm{i}}$ ) plane and find that the positions of some famous recurrent novae, as well as a supersoft X-ray source (SSS), RX J0513.9-6951, are well explained by our model. The model can also explain the space velocity and mass of Tycho G, which is now suggested to be the companion star of Tycho’s supernova. Our study indicates that the SSS, V Sge, might be the potential progenitor of supernovae like SN 2002ic if the delayed dynamical-instability model due to Han and Podsiadlowski (Mon. Not. R. Astron. Soc. 368:1095, 2006) is appropriate. Following the work of Meng et al. (Mon. Not. R. Astron. Soc. 395:2103, 2009a), we found that the SD model (WD+MS) with an optically thick wind can explain the birth rate of supernovae like SN 2006X and reproduce the distribution of the color excess of SNe Ia. The model also predicts that at least 75% of all SNe Ia may show a polarization signal in their spectra.     

广西钦州湾海岸带孢粉组合和沉积环境演变

对广西钦州湾海岸滩涂的4个钻孔的沉积物进行孢粉分析,结合 210Pb法测得沉积速率,讨论了该地区大约150年来的沉积环境演变规律.钦州湾地区具有19世纪中-末叶较现在偏凉的区域性气候; 20世纪初期西海岸沉积物中红树林花粉Rhizophora和Aegiceras锐减,反映出红树林滩衰退的特征; 60年代和70年代,钦州湾西海岸线明显向内陆迁移,高潮滩环境向低潮滩演化; 而80年代始,东海岸线由于钦江流域来沙的迅速堆积,沉积速率较高,岸线向海推移明显,沉积物中木本植物花粉和禾本科均有所增加,这和围垦修堤的人类活动加速了低潮滩向高潮滩演化有关.钦州湾总体表现出西向扩张,东向缩减的趋势.     

华北地块北缘中元古界几个重要不整合面的地质特征及构造意义

华北地块北缘中元古代沉积层序中出现多个沉积间断和不整合面。此次研究对其中5个不整合面进行了野外考察,分析了它们的地质特征和空间分布,认为它们与不同的地质过程有关。大红峪组底部不整合面是早期裂谷盆地演化为被动大陆边缘的记录,属于裂解不整合面性质;高于庄组底部和杨庄组底部的不整合面是海平面变化造成被动大陆边缘内部高地沉积间断和海岸超覆沉积的结果;铁岭组顶部不整合面可能与弧后环境发生挤压抬升有关;下马岭组沉积后的抬升可能是相邻大陆地块碰撞作用的产物。华北地块北缘中元古代层序中不整合面的形成与Columbia和Rodinia超大陆的形成和裂解过程密切相关。     

汶川M_w 7.9级地震同震断层陡坎类型与级联破裂模型

2008年5月12日,汶川Mw7.9级地震在青藏高原东缘沿龙门山逆冲断裂带中段形成了两条NE向和一条NW向逆冲走滑型地表破裂。依据同震地表陡坎形态特征,将其分为8种类型:逆断层陡坎、上盘垮塌陡坎、挤压推覆陡坎、右旋挤压推覆陡坎、断层相关褶皱陡坎、后冲挤压陡坎、上冲叠覆陡坎和局部正断层陡坎。汶川地震所形成的同震地表破裂主要由以逆冲为主的映秀破裂段和兼具逆冲、右旋走滑的北川破裂段两部分组成,这两个破裂段分别对应于Mw7.8与Mw7.6级地震事件;它们还可进一步细分为分别对应于Mw7.5、Mw7.7、Mw7.0和Mw7.5等4个次级事件的4个次级破裂段。这些次级破裂段的级联破裂可以用来解释为什么汶川地震的持续时间长达110 s。余震震源机制分析结果表明,发震断层的倾角随深度的增加而变缓,且从西南向北东逐渐变陡可以用来解释走滑分量增加的成因。此次大地震还表明,沿青藏高原东缘地形抬高的主要驱动力可能是地壳挤压缩短,而不一定是下地壳物质流动和膨胀引起上地壳的隆升。