Redescription of the skull of Saurolophus osborni Brown 1912 (Ornithischia: Hadrosauridae)     

Phil R. Bell 《Cretaceous Research》2011,32(1):30-44

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Vegetation and Climate Reconstruction of the Planalto in Rio Grande do Sul, South Brazil (Late Glacial and Holocene)     

M.Herrmann  A.R.Ashraf  V.Mosbrugger  M.M.Toigo 《世界地质(英文版)》2003,6(2)

A 405 cm long core was drilled in the Aparados da Serra National Park (Rio Grande do Sul, Brazil) at the end of 1999, and in all, 23 samples were taken for palynological investigation. The cores′ age is estimated at 27 000 a BP based on three radiocarbon dates taken from different depths of the core. Palynological methods were used to reconglacial conditions mainly influenced by the South Pole throughout several transition stages to today's humid warm climate, mainly being influenced by the Brazil stream.  相似文献   

京杭大运河镇江段近岸土壤重金属含量与空间分布特征     

李健  汪传胜  吴桂松 《江苏地质》2021,45(2):219-224

通过多目标区域地球化学调查方法,研究了京杭大运河镇江段流域近岸土壤中重金属元素的含量、来源及空间分布特征。结果表明：重金属含量总体较低,仅局部地区存在重金属污染,其中Cr、Ni、As未见明显污染,Cu、Pb、Zn、Hg、Cd在局部地区存在不同程度的污染,尤其是Cd污染最严重;污染区域主要位于辛丰镇和丹阳城区附近,污染源主要为附近的金属制品业和钢铁厂。  相似文献   

Hillslope coupled stream morphology,flow conditions,and their effects on detrital sedimentology in Garnet Canyon,Teton Range,Wyoming     

Lisa M.Tranel 《地学前缘(英文版)》2018,9(4):1193-1202

Characterizing stream erosion in any steep mountain landscape is arduous, but the challenge level increases when the stream flows through a glaciated catchment frequently modified by hillslope debris.Glacial landforms and stochastic mass wasting in alpine systems may interfere with sediment delivery to downstream sites where detrital sediments are often collected to represent upstream bedrock sources.To use detrital sediments as indicators of erosion, we need to understand potential sediment accumulation in flat glaciated reaches or behind rockfall barriers. This study investigates the stream channel in Garnet Canyon, a glaciated catchment located in the central Teton Range, to describe hillslope coupled channel morphology and the subsequent effects on sediment transport throughout the catchment.Stream cross-section surveys and sediment size measurements of the surface bedload were collected in the field within a glacially flattened segment of Garnet Canyon. Calculations of shear stress conditions allowed evaluation of the importance of mineral densities on potential grain entrainment. The length of the Garnet Canyon stream observed in this study was coupled with hillslope deposits. Critical shear stresses were sufficient to move gravel-sized sediments through all sections when calculated with quartz mineral density and through most sections when applying apatite mineral density. These results verify the application of detrital sediments to evaluate erosion rates or spatial bedrock sources because snowmelt stream flow efficiently moves entrained sediment past glacially reduced slopes and potential talus barriers.  相似文献   

琼东南盆地中央峡谷天然气成藏特征及其主控因素   总被引：1，自引：0，他引：1  

许怀智  张迎朝  林春明  裴健翔  刘云芝 《地质学报》2014,88(9):1741-1752

基于地震、测井、岩芯、岩屑和天然气样品分析化验等资料,研究了中央峡谷天然气成藏特征,探讨了成藏主控因素与成藏模式。研究结果表明,晚中新世—早上新世沿琼东南盆地中央坳陷发育一条大型海底峡谷,称之为中央峡谷,峡谷内充填了多期相互叠置的浊积砂岩,平均孔隙度为15%~33%,渗透率为11×10-3~971.3×10-3μm2,为较好的储层;发育了岩性和构造-岩性复合两大类圈闭。峡谷的气源来自于崖城组的煤系地层,属于煤型气。烃源岩的有机质类型为Ⅱ2和Ⅲ型,以Ⅲ型为主;热演化程度处于成熟—高成熟阶段,晚中新世—上新世达到生烃高峰。琼东南盆地中央坳陷是一个高温高压的坳陷,实测地温梯度平均值高达4.2~4.6℃/100m,实测压力系数为1.20~2.15。在高温高压的环境下,盆地内孕育众多的底辟构造,而峡谷下伏的底辟构造与谷内相互叠置的复合砂体在空间上有效的配置构成了天然气垂向与侧向运移的输导体系,成为峡谷天然气成藏的关键因素。  相似文献   

雅鲁藏布江大拐弯地区河流形态特征及其意义   总被引：2，自引：0，他引：2  

黄文星  王国灿  王岸  曹树钊  曹凯 《地质通报》2013,32(1):130-140

为探讨雅鲁藏布江大拐弯地区区域隆升的特点,通过DEM(数字高程模型)和遥感影像提取雅鲁藏布江干流和帕隆藏布江的形态特征,引入Hack剖面、SL参数和Amos河宽理论模型进行分析。雅鲁藏布江干流在大渡卡以下河段的Hack剖面表现为上凸形态,SL参数升高、河流宽度减小,在藏布巴东瀑布-雅鲁藏布江大拐弯顶端段,SL参数达到最大值,河流宽度达到最小值;大拐弯顶端以下河段,SL参数减小,河流渐宽。帕隆藏布江古乡以下河段SL参数梯级增高,河流宽度总体收窄,大拐弯顶端附近达到最大值。综合2条河流的地貌特征和区域地质与地理背景,认为雅鲁藏布江大拐弯地区的隆升具有不均一性,雅鲁藏布江在大渡卡附近开始进入快速隆升区段,隆升最强烈的区段位于藏布巴东瀑布-大拐弯顶端段,大拐弯顶端之后雅鲁藏布江逐渐远离隆升中心区。  相似文献   

台湾峡谷HD133柱状样中重力流、底流交互沉积的证据     

徐尚  王英民  彭学超  邱燕  李卫国 《地质学报》2012,86(11):1792-1798

在台湾峡谷水深3284 m处全长699 cm的HD133柱状样中共识别出1个厚沙层（厚127 cm）和8个薄沙层（单层厚度8-15 cm）,这些沙层中含大量浅水底栖有孔虫,反映其为来自浅水区的陆源物质以重力流方式形成的沉积物。然而,单用重力流无法对这些沙层的成因作出合理的解释：该样中的厚沙层以中沙为主,平均粒径范围1-2Φ,薄沙层以粉沙-细沙为主,平均粒径范围3-4Φ;沙层的分选系数小于2.5,局部接近于1,分选好-极好,长石/石英比值低,具有很高的结构成熟度和成分成熟度;在粒度特征上,其频率分布曲线为单峰,累积概率曲线为2-3段式,在C-M图上厚沙层的样点落在牵引流区域;特别是在垂向序列上,沙层顶底呈突变接触;以上特征均表现为明显的牵引流特征。此外,在柱状样中发现含有太平洋深层水所特有的底栖有孔虫Bulimina aculeata、Planulina wuellerstorfi、Eggerella bradyi种类,且大量生物壳呈棱角状破碎,表明该样在沉积过程中受到太平洋深层水的入侵,这些证据支持了前人关于研究区内可能发育活跃的底流作用的推断。综合分析认为HD133柱状样中的沙层是重力流和底流交互作用的产物。  相似文献   

四川邻水华蓥山大峡谷地质公园地质遗迹资源体系及地学意义     

罗培  秦子晗  孙传敏 《地球学报》2013,34(6):738-748

华蓥山大峡谷地质公园是以峡谷、构造和岩溶地貌为代表的风景地貌类地质公园。本文以华蓥山大峡谷地质公园地质遗迹景观资源为基础, 以川东褶皱带构造单元、川东平行岭谷地貌单元和上扬子地层分区的部分地层区域为研究视角, 构建华蓥山大峡谷地质公园地质遗迹资源体系——包括地质(体、层)剖面、古生物活动遗迹、地貌景观、水体景观以及环境地质遗迹5个大类、15个类共100多处地质遗迹景点; 通过对各类地质遗迹的特征进行分析, 对前人研究进行总结, 探讨了地质公园地质遗迹重要的地学意义。研究表明, 华蓥山大峡谷地质遗迹在地质构造、地层、岩溶学、水文地质学以及地貌学等领域具有重要的科学价值。  相似文献   

The opening of the Plio-Quaternary Gibraltar Strait: assessing the size of a cataclysm     

Paul-Louis Blanc 《Geodinamica Acta》2013,26(5-6):303-317

Abstract

The widespread Lago-Mare facies show that the Mediterranean was fully isolated from the World Ocean at the end of the Messinian salinity crisis (MSC): the Plio-Quaternary Gibraltar Strait has no geographical feature in common with the Miocene Portals, which were continentalised before the end of the MSC. A copy of a budget model has been modified to study the infilling of the Mediterranean. The yearly Atlantic water supply follows an exponential increase law. The level of the basins does not change significantly during the 26 early years, but the refill of the Mediterranean basins is completed within the next 10–11 years. The high velocity of the flow of Atlantic water can be reconfirmed by hydraulic calculations. The morphological study of the area suggests that the Gibraltar Strait originates from an eastwards flowing stream, which drained the eastern slope of an emergent Gibraltar Isthmus to the Mediterranean Basins at the end of the Messinian. Similar canyons are still found in the marine topography towards the Alboran Sea. The present Spartel and Camarinal Sills both originate from the coeval mass sliding of the northern bank of the strait. The strait of Gibraltar results from the work of a stream, which managed water-piracy from an Ocean. © 2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.  相似文献   

中国明、清时期黄河和京杭大运河地图的特征与价值     

姜莉莉  齐清文  赵锴 《地球信息科学学报》2016,18(1):39-48

黄河是中华民族的母亲河,而京杭大运河则担负着河运的重要职责,其重要性决定了古代关于黄运工程及其治理的地图数量繁多。本文旨在通过对大量明、清时期黄河、京杭大运河水利地图的梳理,对明、清时期水利地图的载体形式、表现形式和绘制特点进行剖析,并探讨其在地理学、地图学、水利学方面的应用价值和研究价值。明、清时期的黄河、京杭大运河地图,从载体形式来分,主要分为水利典籍（志书、图说）附图和绘本舆图2类：前者多为示意性地图,画法比较简单,只起到辅助说明水利典籍的作用;后者多采用山水形象画法绘制,多为长卷展开景物再现式地图,其主要特点是形象直观。其采用的“对景法”地图表现形式（即所绘黄河、京杭大运河两岸各类地物要素均朝向河流中心线）,容易引起读者的视觉共鸣,轻松构筑被描画事物的整体画面。从表现形式和绘制特点来看,明、清时期还出现了另外2类地图：计里画方类地图和经纬度实测地图,但由于其实用性和艺术性不如山水形象画法地图,因此,这2类地图在明、清并没有得到广泛普及。但从功能和价值而言,不论是长卷展开式古地图、计里画方类古地图,还是经纬度实测地图,对于古地图史、历史地理学、古代水利研究,对如今的地图、水利、地理学研究等,都是不可多得的历史瑰宝。  相似文献