Barium-rich fluids and melts in a subduction environment (La Corea and Sierra del Convento mélanges,eastern Cuba)

Whole-rock compositions of muscovite-bearing amphibolite, trondhjemite, pegmatite and quartz-muscovite rocks from Sierra del Convento and La Corea mélanges (eastern Cuba), as well as mineralogy, record complex circulation of Ba-rich fluids and melts in the subduction environment. Partial melting of fluid-fluxed, MORB-derived amphibolite produced trondhjemite magmas that crystallized at depth, in some cases evolving into pegmatites. Qtz-Ms rocks probably crystallized from primary fluids derived from subducted sediments. All these rocks have elevated concentrations of large-ion lithophile elements, especially Ba (up to 11,810 ppm), presumably released from slab sediments by fluids and/or melts. Fluid–rock interaction produced crystallization of phengite in parental amphibolites. The phengite crystallized in all types of rocks is rich in Ba, with concentric zoning, characterized by Ba-rich cores and Ba-poor rims, indicating a compatible behaviour of Ba in the studied systems. Zoning in phengite is governed primarily by the celadonite (tschermak) exchange vector ((Mg,Fe)Si-(Al)_-2), with more moderate contributions of the celsian (BaAl-(KSi)_-1) and paragonite (NaK_-1) exchange vectors. Late remobilization of Ba at relatively low temperature formed retrograde celsian. The compatible behaviour of Ba in the studied rocks strengthens the importance of the stability of phengite for the transfer of LIL elements from the subduction to the volcanic arc environments.     

Estimation of snow and glacial melt contribution through stable isotopes and assessment of its impact on river morphology through stream power approach in two Himalayan river basins

The impact of increased temperature on the Third Pole, as the Himalayas is referred to, and the likely cascading impacts on the general downstream hydrology have been widely noted. However, the impact on fluvial geomorphology has not received specific attention. Change in the glacial domain in terms of melt increase will change discharge and sediment flux into fluvial system, which will induce changes in fluvial processes and forms. The present work attempts to study this process-based glacio-fluvial coupling in the two neighbouring glaciated river basins in the Northwest Himalaya, viz., the Sutlej and the Yamuna river basins till the mountain front. A total of 194 samples of river, tributary and groundwater of pre- and post-monsoon seasons in the two river basins were analysed for stable isotopes. The trend of δ¹⁸O and electrical conductivity along the mainstream gives qualitative idea on the influence of headwaters in the downstream of the catchment thereby allowing inference on melt contribution. Further, two component mixing model using stable oxygen isotope of two seasons water samples showed that melt contributes about 41.1–66.8 and 6.6–10.6% at different points to the total river discharge in the Sutlej and the Tons River (the glaciated, major tributary of the Yamuna River) basins, respectively. For different scenarios of increase in melt, stream power increase in the Sutlej River basin is significant as opposed to the Tons River. River channel in the Sutlej River basin will be significantly more impacted in comparison with the Yamuna River system.     

豫陕鄂交界区县域综合发展水平测度及障碍因子分析

以豫陕鄂交界区为研究对象,测度2000—2017年豫陕鄂交界区县域的综合发展水平,探析其空间分异特征、演化趋势和障碍因素。结果表明：① 2000—2017年,豫陕鄂交界区县域综合发展水平逐步提升,年均增速为6.08%,县域间发展的空间差异逐渐增大;② 县域综合发展水平在空间上呈正相关性,热点显著区呈现由东南部向西南部再向东南部迁移变化特征,冷点显著区在2005年前主要分布在安康市和商洛市,之后主要聚集在南阳市;③ 人文和经济要素为中度和中高障碍水平,资源和环境要素为极低和低障碍水平;随着时间的推移,障碍因子在不同县域空间阻力的分异特征更加显著。④ 豫陕鄂交界区县域发展空间阻力模式可划分为3种类型,其中人文资源要素制约型是主要的空间阻力模式。最后,基于不同空间阻力模式特征解析,提出了分区发展策略。     

岱崮地貌的基本特征、成因和演化

岱崮地貌是一种寒武系碎屑岩之上的平顶灰岩地貌,为中国五大地貌之一,对其研究具有地质学、古地理环境等科学意义。本文通过野外地质调查及室内研究,分析研究了岱崮地貌的特征、成因和演化,得出以下结论：1） 岱崮镇的崮主体呈NW向展布,由崮体和崮基组成。崮体包括崮顶、崮腰和崮底,崮顶为灰岩,崮腰和崮底以碎屑岩为主,崮基为前寒武系岩浆岩或太古宇泰山群;2） 近水平岩层是岱崮地貌发育的基础;3） NNW向、NW向和近EW向断层是岱崮地貌形成的根本因素,NW向和NE 向节理是主控因素,控制了岱崮地貌的走向、密度;4） 岱崮地貌古生代以来经历了多个时期的演化,经过加里东运动、海西运动和印支运动留存的寒武系-中奥陶统、上石炭统-二叠系是岱崮地貌形成的基础,燕山期中侏罗世末-晚侏罗世（162～149.8 Ma）、白垩纪（140～90 Ma）及喜马拉雅早期（65～43 Ma）产生的断层及节理是岱崮地。     

公元1328～1330年寒冷事件的历史记录及其意义

元人刘岳申记载了公元1328、1329、1330年连续三年间,江西先后遭遇了大雪、江河结冰与夏季低温等百年罕见的寒冷气候。公元1328～1329年降雪的南界至少已达南岭;公元1329年冰冻的南界至少已达北纬27度左右的吉水县,而江西南部地区公元1330年夏季气温与我国北方坝上地区相当。此降温幅度已与17～19世纪明清小冰期中的极端寒冷年份相近,在过去2000年中亦属于并不多见的极端寒冷年份。     

Potential impact of ash eruptions on dairy farms from a study of the effects on a farm in eastern Bay of Plenty,New Zealand; implications for hazard mitigation

This paper investigates the impact ash fall would have on dairy farming, based on a study of ‘Tulachard’, a dairy farming operation at Rerewhakaaitu, North Island, New Zealand. It includes analysis of the potential effects on the dairy shed and milking machine, electrical supply and distribution, water supply and distribution, tractors and other farm vehicles, farm buildings (haysheds, pump sheds, implement sheds, etc.), milk-tanker access to the farm and critical needs of dairy cows and farm to keep milking. One of the most vulnerable areas identified in the study was the cooling of milk at the milking shed, pending dairy tanker pick-up. The cooling system’s condenser is exposed to the atmosphere and falling ash would make it highly vulnerable. Laboratory testing with wet and dry ash was conducted to determine its resilience to ash ingestion. It was found to perform satisfactorily during dry testing, but during wet testing significant clogging/blocking of the condenser’s radiator occurred, dramatically reducing airflow through the condenser. Specific mitigation recommendations have been developed that include cleaning with compressed air and adapting farm management techniques to lessen usage of the condenser during an ash-fall event. Specific recommendations for management of dairy farm operation are given to mitigate the effects of an ash-fall event.

The mitigation of the vibration effects caused by tunnel blasts in urban areas: a case study in Istanbul

Ground vibrations generated by commercial explosives in tunnel construction may cause structural damage in urban areas. Therefore, suppressing the vibration effects and mitigating the possible hazard after blasting is important. We present a new method of controlled blasting that is environmentally friendly, and easy to utilize for tunnel construction. Small charges in this method are detonated sequentially to produce minimum side effects. The efficiency of the charges may be increased based on the previously monitored shots. This method is utilized in a tunnel construction in Istanbul with five experimental shots. In these experiments, the duration and also the quantity of explosives were carefully controlled. We were able to obtain better results with short durations (480 ms) instead of long durations (9,000 ms) although the vibration levels defined as peak particle velocity (PPV) became bigger while the quantity of the explosive charge increased from 3.088 to 9.264 kg.     

大兴安岭北段诺敏大山地区早白垩世侵入岩地球化学特征及其构造意义

本文选择大兴安岭北段诺敏大山地区早白垩世侵入岩进行了锆石U-Pb年代学和地球化学研究,探讨该区域侵入岩成因类型、岩浆来源及构造环境。该区侵入岩岩性主要为正长花岗岩、正长花岗斑岩和似斑状正长花岗岩,对其中正长花岗岩样品进行LA-ICP-MS锆石U-Pb测年表明,正长花岗岩侵位年龄为129.5±0.4 Ma,应为早白垩世岩浆活动的产物,结合区内侵入岩与地层相互接触关系,本区侵入岩形成时代为早白垩世。区内侵入岩具有富硅（SiO2= 67.36%~74.09%）、富碱（K2O+Na2O= 8.88%~9.34%）、高铝（Al2O3= 12.56%~16.15%）,低MgO、TiO2、CaO的特点,属于高钾钙碱性岩石系列;铝饱和指数（A/CNK）为0.94~1.31,为准铝质—过铝质岩石。微量元素富集Rb、U、Th、K等大离子亲石元素,强烈亏损Ti、Nb、Sr、P等高场强元素,具有明显的Eu负异常,属于高分异I型花岗岩。岩石Rb/Sr为0.9~2.0,Sr/Y为4.2~7.2,显示出高Sr、低Y的特点,指示岩浆源区为地壳物质的部分熔融。结合区域研究成果,蒙古—鄂霍茨克构造域在早白垩世之前已结束碰撞,诺敏大山地区早白垩世岩浆活动可能发生在蒙古—鄂霍茨克造山后的伸展环境。     

NCL在气象数据图形化中的应用

介绍了NCL在PC_LINUX上的安装，以及NCL数据图形化的编程方法，结合常用气象数据处理方法在NCL中的实际应用，与一般的图形显示软件GRADS对比，表明NCL在图形绘制方面的优越性。     

Role of land-surface temperature feedback on model performance for the stable boundary layer

At present a variety of boundary-layer schemes is in use in numerical models and often a large variation of model results is found. This is clear from model intercomparisons, such as organized within the GEWEX Atmospheric Boundary Layer Study (GABLS). In this paper we analyze how the specification of the land-surface temperature affects the results of a boundary-layer scheme, in particular for stable conditions. As such we use a well established column model of the boundary layer and we vary relevant parameters in the turbulence scheme for stable conditions. By doing so, we can reproduce the outcome for a variety of boundary-layer models. This is illustrated with the original set-up of the second GABLS intercomparison study using prescribed geostrophic winds and land-surface temperatures as inspired by (but not identical to) observations of CASES-99 for a period of more than two diurnal cycles. The model runs are repeated using a surface temperature that is calculated with a simple land-surface scheme. In the latter case, it is found that the range of model results in stable conditions is reduced for the sensible heat fluxes, and the profiles of potential temperature and wind speed. However, in the latter case the modelled surface temperatures are rather different than with the original set-up, which also impacts on near-surface air temperature and wind speed. As such it appears that the model results in stable conditions are strongly influenced by non-linear feedbacks in which the magnitude of the geostrophic wind speed and the related land-surface temperature play an important role.