Asian summer monsoon precipitation recorded by stalagmite oxygen isotopic composition in the western Loess Plateau during AD1875―2003 and its linkage with ocean-atmosphere system

Based on 5 high-precision ^230Th dates and 103 stable oxygen isotope ratios （51eO） obtained from the top 16 mm of a stalagmite collected from Wanxiang Cave, Wudu, Gansu, variation of monsoonal precipitation in the modern Asian Monsoon （AM） marginal zone over the past 100 years was reconstructed. Comparison of the speleothem δ^18O record with instrumental precipitation data at Wudu in the past 50 years indicates a high parallelism between the two curves, suggesting that the speleothem δ^18O is a good proxy for the AM strength and associated precipitation, controlled by ＂amount effect＂ of the precipitation. Variation of the monsoonal precipitation during the past 100 years can be divided into three stages, increasing from AD 1875 to 1900, then decreasing from AD 1901 to 1946, and increasing again thereafter. This variation is quite similar to that of the Drought/Flooding index archived from Chinese historical documents. This speleothem-derived AM record shows a close association with the Pacific Decadal Oscillation （PDO） between AD 1875 and 1977, with higher monsoonal precipitation corresponding to cold PDO phase and vice versa at decadal timescale. The monsoonal precipitation variation is out of phase with the PDO after AD 1977, probably resulting from the decadal climate jump in the north Pacific occurring at around AD 1976/77. These results demonstrate a strong linkage between the AM and associated precipitation and the Pacific Ocean via ocean/atmosphere interaction. This relationship will aid to forecast future hydrological cycle for the AM monsoon region, and to improve forecasting potential of climatic model with observation data from cave.     

桥梁桩基特大溶洞处理方法的研究与应用

介绍了湖南省郴宁高速公路水龙互通主线桥右幅32#墩1#桩基溶洞成功处理的工程实例.该桩地质复杂,溶洞发育、埋深大、溶洞成串状分布、最大高度21m,通过分级注浆和分级下钢护筒的方法,成功对其进行处理,成桩后,现场声测结果表明,该桩为I类桩.     

丰都张口洞“兴义人”古文化遗址公园建设可行性研究

享有“丰产之地、古居之都”的丰都是兴义市百万人口城市建设拓展的重要区域.张口洞古文化遗址是“兴义人”古文化遗址的核心地带,在此建设“兴义人”古文化遗址公园,条件具备、区位优越、切实可行.     

芙蓉洞CO2变化特征初探

通过2009年9月～2010年11月对芙蓉洞11个监测点CO_2浓度连续监测,发现芙蓉洞CO_2浓度有一定时空变化特征。空间上,由于洞穴环境封闭,洞内CO_2浓度总体上从洞口到洞尾增长,同时游客人数,洞道形状等因素对其产生一定影响;季节上,CO_2浓度与洞穴外部环境有一定的响应关系,冬季外界温度较低,降水量较少,洞内CO_2浓度也较低。     

独立式窑洞地震作用下损伤指标研究

定量地评估结构在地震作用下的损伤是地震工程领域的研究重点,增量动力分析方法已被广泛用于建筑结构地震易损性评估,而结构损伤指标是定量评估结构损伤情况的重要参数,山西北部农村地区的独立式土坯窑洞是一种拱受力结构体系,为研究拱结构在地震作用下的破坏特征并确立结构损伤指标,结合实际震害与数值模拟试验,分析了窑洞结构在地震作用下的破坏特征,对比了窑洞结构的顶点水平位移和拱顶竖向位移在不同地震动峰值加速度下与结构损伤情况对应关系,发现窑洞拱顶竖向位移与窑洞拱矢高作为窑洞损伤指标较为合理。     

济南龙洞景区河流袭夺探析

在大量野外实地考察的基础上，研究了济南龙洞景区的河流袭夺现象．阐明了河流袭夺的形态特征，并根据地貌面与沉积证据判定了河流袭夺发生的时代，从而揭示了龙洞景区深谷与陡崖的形成过程．研究表明：龙洞景区河流袭夺发生于第四纪初期，是研究区造景地貌形成的主要外营力．其成因不仅与河流侵蚀能力的差异有关，还与流域地貌演进阶段、区域岩性及构造特征、气候及海平面变化等因素密切关联．     

重庆武隆芙蓉洞洞穴景观美学评价

重庆武隆芙蓉洞景观之美已被世人广为认可，本文尝试对其美学价值进行定量评价，根据该洞穴景观的分布特点和景观评价可操作性的要求，本文把整个景观分为7个小景区，并从美学评价的要求出发，选取了6个评价指标和19个次一级的评价因子，采用了层次分析法和加权法(征询法)，进行了定量评价。     

Paleotemperature changes over the past 3000 years in eastern Beijing,China:A reconstraction based on Mg/Sr records in a stalagmite

The Mg/Sr ratio in a stalagmite,whic is directly proportinonal to DMg/Ca,the solid-liquid distribution coefficient of Mg,is proposed as a geochemical thermometer to estimate paleotemperature changes,The paleotemperature change in eastern Beijing over the past 3000 years has been reconstructed by using this thermometer in the stalagmite ZFFS-1 from Jingdong Cave,The records can be divided into two periods:3000-2000 aBP,cool and wet ,the air temperature averaging 9.8℃;and 2000aBP-present, hot and dry,the air temperature being 1℃ higher than the mean value (11.7℃) of the past 3000 years ,During 500-200 aBP,the air temperature was about 1.2℃ lower than that of the present,corresponding to the Little Ice Age Europe Like δ^18O and δ^C ,Mg/Sr (or DMg/Ca) reflects and obviously warming trend of the past 200 years,These results are supported by historic recods.     

龙门石窟艺术特色刍议

佛教石窟艺术越过葱岭、传入我国后,逐渐形成了它在中国的发展特色,洛阳的龙门石窟便是在很大程度上吸收融合和改造了印度和中亚的佛教艺术,形成了具有中原王朝皇家风范和民族特色,地方特色并且闪烁着传统艺术和现实主义手法自然结合光辉的新艺术。     

贵州织金岔河铝土矿含矿岩系特征及成矿因素探讨

为深化黔中铝土矿的研究,在贵州中部铝土矿西南缘的织金岔河地区选取了仰天窝、堰塘和大栗树三条铝土矿含矿岩系剖面进行了系统描述及采样。经分析得出本区铝土矿含矿岩系具有下部铁质层,上部铝质层的铁-铝结构特征。具有沉积环境指示意义的Sr/Ba值、Th/U值、δCe值表明本区的沉积环境大体如下:东端的堰塘剖面在铝土矿沉积时地势较低,且距离海岸相对较近,受海水侵入的影响较为强烈;西端的大栗树及南端的仰天窝剖面在铝土矿沉积时相对远离海岸,受海水的影响较小,主要为淡水沉积。结合成矿特征,反映出弱还原环境、淡水沉积的大栗树剖面较有利于优质铝土矿的形成,还原环境、受海水影响的堰塘剖面成矿环境最差。综合分析,表明成矿物源来源于研究区北面,大栗树和仰天窝间的区域可作为下步勘查的有利区域。