Snow in Lebanon: a preliminary study of snow cover over Mount Lebanon and a simple snowmelt model / Etude préliminaire du couvert neigeux et modèle de fonte des neige pour le Mont Liban

Abstract

The physical properties of snow, including apparent density, snow cover distribution and snowmelt in the Nahr El Kelb basin (Mount Lebanon), were studied in order to design a simple empirical snowmelt model. In February 2001, snow covered an area of 1600 km² on Mount Lebanon, representing a water equivalent of 1.1 x 10⁹ m³. The snow surface area was calculated by combining TM5 images with a digital elevation model, and field observations made every three days, from 1400 to 2300 m altitude. The depletion of snow cover was measured from the end of December 2000 to the end of June 2001. The snowmelt was measured from surface depletion on a degree-day basis. A simple model relating the daily snowmelt to the product of wind speed and average positive daily air temperature, is presented and discussed. For Mount Lebanon, this model gave a better approximation of snowmelt than a simple degree-day model.     

泰山南坡沉积物特征及第四纪冰缘环境探讨

针对泰山第四纪冰川有无的争议,在泰山南坡采集沉积物样品进行分析研究。孢粉分析结果显示优势植物种群为“松属＋中华卷柏＋蒿属＋藜科”,指示的沉积环境为湿冷环境。扫描电镜观察石英颗粒表面,显示出边缘棱角清晰、具贝壳状断口和解理片的冰川环境特征。通过热释光测试得样品年龄为（30．54±2．59）kaB．P．,相当于末次冰期主冰期中的Paudorf-Stillfried间冰阶。根据泰山现代气候环境推演泰山古气候温度和降水量,得出泰山地区在末次冰期时具备了形成冰川的基本气候条件。鉴于Paudorf—Stillfried间冰阶持续的时间较短,因此初步推断该沉积物指示的古气候环境为冰缘环境。     

江西三清山国家地质公园内的重大地质事件记录

江西三清山于2005年3月批准为国家地质公园,2008年7月入选世界自然遗产名录,以花岗岩地质与花岗岩峰林地貌著称。拥有10亿年演化历史的三清山,不仅是一个地学等多个领域具有全球研究对比意义的地学宝库,而且是拥有重要科学价值及科普意义的地质遗迹。在申报世界地质公园野外考察的基础上,本文综述了三清山地质遗迹代表性的9个重大地质事件,这也是世界自然遗产开发和保护基础工作以及地质公园管理的要求。     

生态-经济系统对冰冻圈变化的适应能力评价——以玉龙雪山地区为例

以玉龙雪山地区为例,基于关联性、全面性与合理性、可操作性原则,结合玉龙雪山地区冰冻圈变化的特点与主要影响,从生态、水资源、经济与社会系统4个方面遴选了20个指标,构建了生态-经济系统对冰冻圈变化的适应能力评价体系,运用层次分析法和多目标线性加权函数法建立了冰冻圈变化适应能力指数模型,对玉龙雪山地区冰冻圈变化适应能力进行了综合评价.结果表明:就子系统而言,1980-2008年除水资源系统的适应能力呈下降态势外,生态、经济与社会系统对冰冻圈变化的适应能力均呈上升趋势.水资源总量减少是水资源系统适应能力降低的主要影响因素.玉龙雪山地区冰冻圈变化的综合适应能力增强,经济系统对综合适应能力的贡献达到37%,居首位,其次为社会系统,为29%.旅游业发展驱动下的生态环境保护,地区经济实力增强,交通设施建设,居民收入增加共同助推了该地区综合适应能力的提升.     

泰山地区古元古代末期基性岩墙形成时代厘定——斜锆石U-Pb精确定年

华北克拉通经过吕梁运动在～1.85Ga完成克拉通化,之后从1.80Ga至1.32Ga发育大量标志哥伦比亚超级大陆裂解的地质记录。本文利用高精度热电离质谱法(ID-TIMS)和离子探针质谱法(SIMS),对发育于泰山红门景区的辉长辉绿岩墙进行了斜锆石U-Pb同位素年龄测定,获得了在误差范围内一致的辉长辉绿岩侵位年龄1621.1±8.8Ma(ID-TIMS)和1632.4±4.2Ma(SIMS)。该研究成果修正了前人对泰山红门景区辉长辉绿岩侵位年龄的模糊认识,证明了红门景区辉长辉绿岩是与华北克拉通南缘龙王碱性花岗岩、华北克拉通北缘大红峪期碱性火山岩和岩床同期的岩浆事件的产物,是哥伦比亚超级大陆初始裂解作用在华北克拉通的岩浆作用响应。     

卫星激光测距望远镜的指向改正

介绍激光测距望远镜全天区指向改正的实施方法及改正效果。通过实测的恒星指向误差数据,利用经优化的机架模型,对望远镜的全天区指向进行实时改正,基本达到了全天区白天激光测距的指向要求。     

Characteristics of modern atmospheric dust deposition in snow in the Mt. Yulong region,southeastern Tibetan Plateau

We evaluated the concentration, size and distribution, and temporal variation of insoluble dust micro-particles in the snow, rainfall and water taken from the areas surrounding the Mt. Yulong to define the characteristics of modern atmospheric dust deposition and the contributions of different dust sources. The mean mass concentration (4511 μg kg⁻¹) of micro-particles with 0.57 < d < 26 μm, and the diameter (11.5 μm) of dust contained in the water bodies of the Mt. Yulong are roughly similar to those observed in other sites, implying that dust is primarily supplied through short-range transport from proximal source regions (several or hundreds of km distances). The mean mass concentrations of micro-particles with 0.57 < d < 26 μm is lower in the rainfall than in the snow and the river water, suggesting the rain water is an ideal source/carrier for detecting the characteristics of modern atmospheric micro-particles. Volume size distributions of micro-particles in the snow and water showed single modal structures having volume median diameters from 3 to 26 μm. Number concentrations of micro-particles in the snow were higher than that in the rainfall, the river water contains the least amount of micro-particles. Vertical profiles of the snowpits show that there is a strong lateral correlation among the dust peaks, indicating a regional uniformity of dust deposition and suitability of snow analysis for dust deposition. In addition, the bare rock of snow-free terrain in the Mt. Yulong region and the mineral particles from local rock weathering are also important sources for the dust deposition.     

Gas hydrate characterization and grain-scale imaging of recovered cores from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

Using cryogenic scanning electron microscopy (CSEM), powder X-ray diffraction, and gas chromatography methods, we investigated the physical states, grain characteristics, gas composition, and methane isotopic composition of two gas-hydrate-bearing sections of core recovered from the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well situated on the Alaska North Slope. The well was continuously cored from 606.5 m to 760.1 m depth, and sections investigated here were retrieved from 619.9 m and 661.0 m depth. X-ray analysis and imaging of the sediment phase in both sections shows it consists of a predominantly fine-grained and well-sorted quartz sand with lesser amounts of feldspar, muscovite, and minor clays. Cryogenic SEM shows the gas-hydrate phase forming primarily as a pore-filling material between the sediment grains at approximately 70-75% saturation, and more sporadically as thin veins typically several tens of microns in diameter. Pore throat diameters vary, but commonly range 20-120 microns. Gas chromatography analyses of the hydrate-forming gas show that it is comprised of mainly methane (>99.9%), indicating that the gas hydrate is structure I. Here we report on the distribution and articulation of the gas-hydrate phase within the cores, the grain morphology of the hydrate, the composition of the sediment host, and the composition of the hydrate-forming gas.     

Tree Population Dynamics of Three Altitudinal Vegetation Communities on Mount Cameroon(1989-2004)

Changes in permanent sample plots in the lowland,submontane and montane forests on Mount Cameroon(4,095 m above sea level),an active volcano,are described for 15 years from 1989 to 2004.Throughout the study period,the stocking level of trees with a diameter at breast height(DBH) ≥ 10 cm in the three forests were lower than in pan-tropical stands suggesting a significant impact of volcanic and human-related activities on the vegetation communities on the mountain.Annual mortality rates in the submontane and ...     

Proterozoic low-pressure/high-temperature metamorphism and an anticlockwise P–T–t path for the Hazeldene area, Mount Isa Inlier, Queensland, Australia

In the Hazeldene area, situated in the Mount Isa Inlier, Queensland, the metamorphic grade changes from chlorite zone, through biotite and cordierite zones, to sillimanite/K-feldspar zone.
Microstructural studies of rocks near the sillimanite isograd demonstrate that cordierite grew early during the development of a steep foliation (S2), was replaced by biotite, andalusite and sillimanite at the metamorphic peak late in S2, and in turn by kyanite + chlorite adjacent to localized small post-D2 shear zones. Although the anticlockwise P–T–t path is well defined, the precise P–T conditions are uncertain because of problems with experimental and thermodynamic data. The best estimate for the metamorphic peak for rocks close to the sillimanite isograd is around 600° C at 4 kbar.
The metamorphism has been dated at 1544 Ma, and was synchronous with a major crustal shortening event. Because proposed extensional events occurred more than 60 Ma earlier, their contribution to the peak metamorphic thermal perturbation would have been insignificant. The syn-metamorphic Mica Creek Pegmatites, the abundance of high heat-producing elements in the nearby pre-D2 Sybella Granite, and advective heat by fluids which caused considerable metasomatism in the Hazeldene area, may have each contributed to the thermal budget. However, the metamorphic thermal gradient may be 80°C km^-1 or higher, strongly suggesting a local magmatic control. As none are known in the area, such syn-metamorphic plutons would have to lie beneath the exposed high-grade rocks.