Simulating the effects of the 1991 Mount Pinatubo volcanic eruption using the ARPEGE atmosphere general circulation model

The climate changes that occured following the volcanic eruption of Mount Pinatubo in the Phillippines on 15 June 1991 have been simulated using the ARPEGE atmosphere general circulation model （AGCM）. The model was forced by a reconstructed spatial-time distribution of stratospheric aerosols intended for use in long climate simulations. Four statistical ensembles of the AGCM simulations with and without volcanic aerosols over a period of 5 years following the eruption have been made, and the calculated fields have been compared to available observations. The model is able to reproduce some of the observed features after the eruption, such as the winter warming pattern that was observed over the Northern Hemisphere （NH） during the following winters. This pattern was caused by an enhanced Equator-to-pole temperature gradient in the stratosphere that developed due to aerosol heating of the tropics. This in turn led to a strengthening of the polar vortex, which tends to modulate the planetary wave field in such a way that an anomalously positive Arctic Oscillation pattern is produced in the troposphere and at the surface, favouring warm conditions over the NH. During the summer, the model produced a more uniform cooling over the NH.     

西藏珠穆朗玛峰北坡地区显生宙沉积演化

位于印度板块北缘和雅鲁藏布江结合带之间的珠穆朗玛峰北坡地区，属于喜马拉雅造山带，是特提斯洋的重要组成部分。自奥陶纪至古近纪约5亿年期间发育一套基本连续的海相沉积，厚度达14 km，是研究特提斯洋形成演化的最佳地区。作者在对该区显生宙地层主干剖面和辅助剖面详细观察研究以及区域地质调查填图的基础上，将珠穆朗玛峰北坡地区显生宙沉积地层划分为海相、海陆过渡相和陆相3个沉积相组、15个沉积相和若干个沉积亚相。作者通过对该区沉积盆地的地层系统、沉积相、沉积特征的系统研究，将珠穆朗玛峰北坡地区显生宙沉积演化划分为6个阶段:1)奥陶纪-泥盆纪为稳定陆表海演化阶段；2)石炭纪-二叠纪为大陆裂谷盆地演化阶段；3)三叠纪-侏罗纪为被动大陆边缘盆地演化阶段；4)早中白垩世为前陆早期复理石盆地演化阶段；5)晚白垩世-古新世为前陆晚期磨拉石盆地演化阶段；6)古近纪-第四纪为造山隆升断陷盆地形成演化阶段。研究结果表明，珠穆朗玛峰北坡地区显生宙沉积盆地经历了由陆表海盆地-大陆裂谷盆地-被动大陆边缘盆地-前陆盆地-断陷盆地的演化过程。     

云南玉龙雪山第四纪冰期与冰川演化模式

云南玉龙雪山高峰区有现代冰川１９条,面积１１．６１Ｋｍ＾２,冰川融水汇入金沙江。在现代冰川外围有丰富的古冰川遗迹,可划分３次更新世冰期,即大理、丽江和云杉枰冰期。相当于欧洲阿尔卑斯的玉木里斯和民德冰期。其中以丽江冰期冰川规模最大,当时,河水冰期的白水河冰川长２．５Ｋｍ,冰川 演化模式与梅里雪山、贡嘎山东坡相同,均属藏东南型,而与青藏高原广大高山区以例数第三次冰不川最大规模有别。主要是它们位于青藏高     

西藏台错盐湖TT-1剖面的沉积特征和年代学研究

台错位于西藏羌塘高原西部,这里因环境恶劣而无人类污染和影响。笔者调查了该湖区一级阶地的湖相化学沉积,取得了TT-1剖面(厚度369cm)连续样品156个,平均单样厚度2．36cm。就台错剖面的年代测定,本文分别对同一样品进行了不同方法的测试和相互校验。研究表明,^14C方法对有机物质的定年是准确的,而在消除盐湖化学沉积建造中碳酸盐的“新碳”、“老碳”的影响方面,仍需做进一步的研究。与此同时,铀系法测年的全溶样品的等时线技术,避免了同位素的分馏问题,所有的测试数据在等时线上都有良好的线形关系,表明获得的年龄数据是合理的。从而确定了TT-1剖面盐湖沉积的可靠地质时代为32．6～4．5ka B P间的晚更新世晚期至全新世中期。     

Crustal structure beneath the Mount Cameroon region derived from recent gravity measurements

In this study, the recent update of the gravity database with new measurements has raised the opportunity of improving the knowledge of the crustal structure beneath the large volcanic system called Mount Cameroon, and its implication in the regional tectonics. The multi-scale wavelet analysis method was applied to highlight the geologic features of the area, and their depths were estimated using the logarithmic power spectrum method. The results reveal a complex crustal structure beneath Mount Cameroon with high variation in the lateral distribution of crustal densities. The upper and lower crusts are intruded by dense materials originating from the mantle with less lateral extension. The trends of Tiko and Ekona faults along the intrusion suggest tectonic activities as deep as 25 km. The difference in mantle composition or temperature between the East and the West of the studied area is clearly seen in detailed wavelet images and agrees with a mantle origin for the Cameroon Volcanic Line.     

绿岩带金矿三位一体成矿及找矿预测——以山东泰安地区为例

对泰安地区东部金（铁）成矿远景区绿岩带金矿成矿条件进行了综合分析研究,对成矿远景区进行了划分.在对绿岩、花岗岩、韧性剪切带三要素在各区段的分布特征和绿岩带金矿成因分类分析的基础上,提出了绿岩带金矿是以韧性剪切带为主线,以绿岩为基础,以花岗岩为导火的三位一体成矿.以100分对三要素进行量化分解,并据此提出了成矿预测.指出成矿远景区内以往的找矿停留在同构造晚期初生型金矿床类型上.今后的找矿工作必须把握“三位一体”成矿模式,分析矿床成因类型,按照矿床成因类型的突出特点针对性地投入工作,必须加大投入,整装勘查.     

泰山玉皇顶三维可视化系统的设计与实现

根据泰山玉皇顶景点的特征,结合现有的地形图、遥感影像和实地调查资料数据,运用三维建模软件和多源数据融合等技术,研发了基于VRM ap的三维可视化系统,为玉皇顶景点的宣传、保护和管理提供了三维的、具有沉浸感的交互平台,从而更好地为旅游管理人员和广大游客服务。     

Applying geomorphological principles and engineering science to develop a phased Sediment Management Plan for Mount St Helens,Washington

Thirty‐seven years post‐eruption, erosion of the debris avalanche at Mount St Helens continues to supply sediment to the Toutle–Cowlitz River system in quantities that have the potential to lower the Level of Protection (LoP) against flooding unacceptably, making this one of the most protracted gravel‐bed river disasters to date. The Portland District, US Army Corps of Engineers (USACE) recently revised its long‐term plan for sediment management (originally published in 1985), in order to maintain the LoP above the Congressionally‐authorized level, while reducing impacts on fish currently listed under the Endangered Species Act, and minimizing the overall cost of managing sediment derived from erosion at Mount St Helens. In revising the plan, the USACE drew on evidence gained from sediment monitoring, modelling and uncertainty analysis, coupled with assessment of future LoP trends under a baseline scenario (continuation of the 1985 sediment management strategy) and feasible alternatives. They applied geomorphological principles and used engineering science to develop a phased Sediment Management Plan that allows for uncertainty concerning future sediment yields by implementing sediment management actions only as, and when, necessary. The phased plan makes best use of the potential to enhance the sediment trap efficiency and storage capacity of the existing Sediment Retention Structure (SRS) by incrementally raising its spillway and using novel hydraulic structures to build islands in the North Fork Toutle River (NFTR) and steepen the gradient of the sediment plain upstream of the structure. Dredging is held in reserve, to be performed only when necessary to react to unexpectedly high sedimentation events or when the utility of other measures has been expended. The engineering‐geomorphic principles and many of the measures in the phased Sediment Management Plan are transferrable to other gravel‐bed river disasters. The overriding message is that monitoring and adaptive management are crucial components of long‐term sediment‐disaster management, especially in volcanic landscapes where future sediment yields are characterized by uncertainty and natural variability. © 2017 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.     

Stability of supraglacial debris

Rock debris on the surface of ablating glaciers is not static, and is often transported across the ice surface as relief evolves during melt. This supraglacial debris transport has a strong influence on the spatial distribution of melt, and is implicated in the formation of hummocky glacial topography in deglaciated terrain. Furthermore, as ice‐dammed lakes and ice‐cored slopes become increasingly common in deglaciating watersheds, there is rising concern about hazards to humans and infrastructure posed by mass‐wasting of ice‐cored debris. The existing quantitative framework for describing these debris transport processes is limited, making it difficult to account for transport in mass balance, hazard assessment, and landscape development models. This paper develops a theoretical framework for assessing slope stability and gravitational mass transport in a debris‐covered ice setting. Excess water pressure at the interface between ablating ice and lowering debris is computed by combining Darcy's law with a meltwater balance. A limit‐equilibrium slope stability analysis is then applied to hypothetical debris layers with end‐member moisture conditions derived from a downslope meltwater balance that includes production and seepage. The resulting model system constrains maximum stable slope angles and lengths that vary with debris texture, thickness, and the rate of meltwater production. Model predictions are compared with field observations and with digital elevation model (DEM)‐derived terrain metrics from two modern debris‐covered glaciers on Mount Rainier, USA. Copyright © 2017 John Wiley & Sons, Ltd.     

内蒙古乌梁素海“黄苔”暴发卫星遥感动态监测

通过综合分析"黄苔"、芦苇、明水体和陆地等地物在EOS/MODIS图像上不同波段的光谱特征,提出了利用EOS/MODIS可见光、近红外波段数据提取"黄苔"信息的方法.结合乌梁素海"黄苔"实地考察资料和高空间分辨率的中巴资源卫星CBERS/CCD数据对MODIS数据监测"黄苔"的结果进行了比对验证.研究结果表明,本文提出的方法可以对"黄苔"进行有效的监测.同时提出了简单可行的去除程辐射影响的大气校正方法,利用MODIS 2008年5-10月的数据对内蒙古乌梁素海的"黄苔"灾情进行了动态监测,获得了乌梁素海"黄苔"灾情发生发展的特征信息,乌梁素海在2008年5月初开始出现"黄苔",6-7月份发生大面积"黄苔"暴发,进入8月以后"黄苔"开始逐渐消退,10月份基本消失,并初步分析了"黄苔"暴发的原因.