新疆库鲁克塔格地区兴地Ⅱ号镁铁-超镁铁质岩体的地球化学特征与岩石成因

兴地Ⅱ号镁铁-超镁铁质岩体位于塔里木盆地东北缘的库鲁克塔格地区,形态为不规则的漏斗状岩盆,出露面积约10km²。岩石类型主要有方辉橄榄岩、二辉橄榄岩、(含长)单辉橄榄岩、橄榄辉石岩、方辉辉石岩、二辉辉石岩、单辉辉石岩、橄榄辉长苏长岩、辉长苏长岩、橄榄辉长岩、辉长岩等,岩石类型属拉斑玄武岩系列。岩体的稀土元素含量低(∑REE=10.73×10^-6~77.44×10^-6),富集轻稀土元素(La/Yb)_N=4.06~7.73和大离子亲石元素(Cs、Rb、Sr、Ba),亏损高场强元素尤其是Nb、Ta、Ti、P等,δEu为0.90~2.46多数岩石显示出正铕异常。岩相学及地球化学特征表明,岩浆运移过程中主要发生了橄榄石、斜方辉石、单斜辉石的分离结晶作用以及斜长石的聚集/堆晶。原生岩浆为富镁拉斑玄武岩,岩浆源区为富集型岩石圈地幔,岩浆上升侵位过程中局部遭受了陆壳的同化混染。兴地Ⅱ号岩体与金川岩体具有很多的相似之处,而且兴地Ⅱ号岩体已见有铜镍矿化。因此,兴地Ⅱ号岩体具有很好的找矿前景。     

Influence de l'hydrodynamique sur l'intrusion saline en aquifère karstique côtier

A new method of interpretation of the $Q\text{–}C$ hysteresis (discharge–salinity) during high water is proposed using the data recorded on coastal brackish karstic springs with salinity inversely proportional to the discharge. The method, based on the $Q_{\mathrm{mer}}\text{–}{C}_{\mathrm{T}}$ (seawater discharge–salinity) hysteresis, identifies the effect of the hydrodynamic changes on the flow and transport. Three phenomena are characterized: the emptying of the karstic conduit, the dilution by freshwater and the control of the seawater intrusion in the conduit by the hydraulic head variations. To cite this article: B. Arfib et al., C. R. Geoscience 338 (2006).     

2009年6月河南一次飑线过程的成因分析

利用地面观测资料、NCEP1°×1°再分析资料和雷达探测资料,从能量、动力和触发机制等角度,对2009年6月3日发生在河南东部地区的一次飑线过程进行综合分析。结果表明:东北冷涡是此次飑线过程的主要影响系统,涡后冷空气南下与低层暖湿空气叠加造成对流不稳定,高层的干冷空气侵入增强了对流不稳定;低层辐合、高层辐散为飑线强对流天气的发生发展提供了强烈上升运动的动力条件,地面维持并加强的干线所激发的次级环流可能是这次飑线系统发生发展的重要机制之一;中低层的垂直风切变稳定维持、加强、迅速减小与飑线强对流天气发生发展前后对应较好,其演变特征对此次飑线过程有很好的指示意义。     

What Causes the Springtime Tropospheric Ozone Maximum over Northeast Asia？

Scientists have long debated the relative importance of tropospheric photochemical production versus stratospheric influx as causes of the springtime tropospheric ozone maximum over northern mid-latitudes. This paper investigates whether or not stratospheric intrusion and photochemistry play a significant role in the springtime ozone maximum over Northeast Asia,where ozone measurements are sparse.We examine how tropospheric ozone seasonalities over Naha(26°N,128°E),Kagoshima(31°N,131°E),and Pohang(36°N,129°E),which are located on the same meridional line,are related to the timing and location of the jet stream.The ozone seasonality shows a gradual increase from January to the maximum ozone month,which corresponds to April at Naha,May at Kagoshima,and June at Pohang.In order to examine the occurrence of stratospheric intrusion,we analyze a correlation between jet stream activity and tropospheric ozone seasonality.From these analyses,we did not find any favorable evidence supporting the hypothesis that the springtime enhancement may result from stratospheric intrusion.According to trajectory analysis for vertical and horizontal origins of the airmass,a gradual increasing tendency in ozone amounts from January until the onset of monsoon was similar to the increasing ozone formation tendency from winter to spring over mainland China,which has been observed during the build-up of tropospheric ozone over Central Europe in the winter-spring transition period due to photochemistry.Overall,the analyses suggest that photochemistry is the most important contributor to observed ozone seasonality over Northeast Asia.     

珠江口近15年海平面变化特点及其与强咸潮发生的关系

通过对珠江口30多年相对海平面和近15年绝对海平面变化的研究,比较1992年12月～2008年12月南海卫星观测和珠江口验潮站观测的海平面变化趋势,认为珠江口的相对海平面（RSL）上升最主要原因是全球气候变暖、海平面上升所致;通过研究29个冬季各月西、北江冬季径流量、海平面、表层盐度的变化趋势,以及强咸潮月份的径流、海平面、盐度的对应关系,得出海平面上升是加大咸潮影响的重要因素。     

干侵入强度指数的表征及其物理意义

综合考虑干侵入的特征、机制和效应,定义了干侵入强度指数(DII)以表征干侵入的强度,并从一个个例进一步揭示干侵入强度指数的物理意义.结果表明,DII是干侵入强度较好的定量描述指标,它与水平温度平流、位涡、假相当位温相关,正的DII表明存在干侵入过程,随着DII的增大,干侵入效应增强,此时可能高位涡异常越强、湿球位温越低、冷平流效应越强;345K等熵面上DII>1PVU/s的正值区与水汽图像暗区较为一致,DII在=三维结构上表现为高层波状下传的特征,在任一特定的等熵面上,低涡西北方向的中高纬度地区是DII正值区的源地;DII体现了水平温度平流效应,低涡降水区西侧为冷平流,东侧为暖平流,冷暖平流一直贯穿于对流层整层,冷平流在西北气流引导下沿等熵面下滑,在冷暖平流交汇处出现降水,随着水平温度平流梯度的增大,对应的降水增强.在实际天气预报业务工作中,DII可用以界定干侵入区域、过程以及强度,具有一定实际业务应用价值.     

Analyses of dry intrusion and instability during heavy rainfall event occurred in Northern China

The 1°×1° National Center for Environmental Prediction/National Center for Atmospheric Research （NCEP/NCAR） data and mesoscale numerical simulation data are analyzed to reveal a mechanism for the formation of heavy rainfall in Northern China; this mechanism is the non-uniformly saturated instability induced by a dry intrusion. The dry intrusion and the accompanying downward transport of air with a high value of potential vorticity （PV） are maintained during the precipitation event. As the dry air intrudes down into the warm and moist sector in the lower troposphere, the cold, dry air and the warm, moist air mix with each other, and, as a result, the atmosphere becomes non-uniformly saturated. On the basis of this non-uniform saturation, a new Brunt-Vaisaila frequency （BVF） formula is derived and applied to the precipitation event. It is shown that, compared to the conditions of either a dry or a saturated atmosphere, the BVF in a non-uniformly saturated, moist atmosphere （BVF） may be more appropriate for depicting the atmospheric instability in rainy regions.     

岩浆硫化物矿床勘查研究的趋势与小岩体成矿系统

通过2009年西安Ni-Cu(Pt)岩浆矿床国际学术研讨会和近10年来的勘查研究现状,可以看出岩浆硫化物矿床勘查领域的发展趋势为:与大型层状岩体有关的铂族矿床仍然受到关注;Sudbury矿床的特殊性和不可参照性取得了共识;小岩体矿床是勘查研究的主流;通道成矿作用受到重视。以大型层状岩体Bushveld为例,介绍了其中的Merensky矿层、UG-2矿层和北翼接触带的Platreef矿床。由于中国没有发现这种大型层状岩体,因此应当重视那些中小型层状岩体中可能赋存的铂族矿床。迄今为止,除了Sudbury矿床这个特殊的实例之外,国内外所有具有经济意义的Ni-Cu矿床都寄生于小岩体中并自成一个成矿系统。这个小岩体成矿系统包含成矿背景、邻近深大断裂、原始岩浆、先导性岩浆成岩作用、继发性岩浆成矿作用以及深部熔离-分期贯入-终端岩浆房聚集成矿等。近10年的勘查实践进一步说明,这类小岩体矿床仍是中国今后的主要勘查研究方向。最后,介绍了Noril sk-Talnakh和Voisey s Bay矿床的深部熔离-通道成矿机制,这种机制增添了小岩体成矿作用的多样性;但是,其现存空间是开放性岩浆通道还是封闭性终端岩浆房,还有待更多的研究和实践。     

2010年8月豫北一次短时强降水过程分析

利用常规观测资料、卫星云图和NCEP全球分析资料（FNL）,对2010年8月13日豫北沿黄地区出现的短时强降水过程进行了诊断分析。结果表明：这次强降水过程是在低槽东移、副高东退南压的形势下,由高、低空急流,中低层切变线,以及地面倒槽和弱冷空气等影响系统共同作用造成的。强降水发生时暴雨区低层水汽辐合跃增,配合强劲的垂直上...     

Does sea-level rise have an impact on saltwater intrusion?

Climate change effects are expected to substantially raise the average sea level. It is widely assumed that this raise will have a severe adverse impact on saltwater intrusion processes in coastal aquifers. In this study we hypothesize that a natural mechanism, identified here as the “lifting process,” has the potential to mitigate, or in some cases completely reverse, the adverse intrusion effects induced by sea-level rise. A detailed numerical study using the MODFLOW-family computer code SEAWAT was completed to test this hypothesis and to understand the effects of this lifting process in both confined and unconfined systems. Our conceptual simulation results show that if the ambient recharge remains constant, the sea-level rise will have no long-term impact (i.e., it will not affect the steady-state salt wedge) on confined aquifers. Our transient confined-flow simulations show a self-reversal mechanism where the wedge which will initially intrude into the formation due to the sea-level rise would be naturally driven back to the original position. In unconfined systems, the lifting process would have a lesser influence due to changes in the value of effective transmissivity. A detailed sensitivity analysis was also completed to understand the sensitivity of this self-reversal effect to various aquifer parameters.