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Temporal and spatial variations in the discharge and dissolved organic carbon of drip waters in Beijing Shihua Cave,China 总被引：1，自引：0，他引：1
To detect the causal relationship between cave drip waters and stalagmite laminae, which have been used as a climate change proxy, three drip sites in Beijing Shihua Cave were monitored for discharge and dissolved organic carbon (DOC). Drip discharges and DOC were determined at 0 to 14‐day intervals over the period 2004–2006. Drip discharges show two types of response to surface precipitation variations: (1) a rapid response; and (2) a time‐lagged response. Intra‐annual variability in drip discharge is significantly higher than inter‐annual variability. The content of DOC in all drip waters varies inter‐ and intra‐annually and has good correlation with drip water discharge at the rapid response sites. High DOC was observed in July and August in the three years observed. The flushing of soil organic matter is dependent upon the intensity of rain events. The DOC content of drip water increases sharply above a threshold rainfall intensity (>50 mm d?1) and shows several pulses corresponding with intense rain events (>25 mm d?1). The DOC content was lower and less variable during the dry period than during the rainy period. The shape of DOC peak also varies from year to year as it is influenced by the intensity and frequency of rainfall. The different drip sites show marked differences in DOC response, which are dominated by hydrological behaviour linked to the recharge of the soil and karst micro‐fissure/porosity network. The results explain why not all stalagmite laminae are consistent with climate changes and suggest that the structure of the rainy season events could be preserved in speleothems. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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酒泉盆地油气勘探始于20世纪20年代,先后发现了老君庙、鸭儿峡、单北、白杨河等油田。盆地在中、新生代经历了早白垩世断陷盆地演化阶段和新生代前陆盆地演化阶段,为断拗叠置型盆地。断陷期的酒泉盆地下白垩统赤金堡组和下沟组为一套纹层状泥质白云岩和白云质泥岩,藻纹层比较发育,是优质的烃源岩。拗陷期盆地的快速沉降导致烃源岩快速成熟、高效生烃,为油气运移提供了动力,同时挤压逆冲对构造圈闭、油气运移通道的形成和储层物性的改善起着关键的作用,形成的窟窿山等多个正向构造带是油气富集的有利区带。青西凹陷存在低成熟、成熟、高成熟3类原油,低成熟原油仅分布于青西凹陷的下沟组上段至中沟组,成熟原油发生了大规模的运移,形成了柳沟庄、鸭儿峡—老君庙—石油沟油田,而深层高成熟原油没有大规模向中浅层运移,青西凹陷具有寻找高成熟原油的资源潜力。希望该研究成果可为青西凹陷下白垩统油气勘探提供经验与思路。 相似文献
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Allen W. Archer 《Mathematical Geology》1994,26(1):47-65
Fine-scale fabric within shales can be used to interpret environments of deposition. In particular, systematic variations in lamina thicknesses can be used to suggest the presence or absence of specific sedimentological controlling factors, such as tides. Herein, shale fabric is analyzed from Carboniferous coal-bearing and siliciclastic-rich formations in Indiana and Kansas. The shales exhibit well developed, normally graded lamina. Sediment grain sizes range from silt and sand at the base of the lamina up to silt and clay at the top. Computer-based optical scanning of prepared shale samples was undertaken so that the lamina thicknesses could be extracted automatically and then used for thickness-series analysis. The sands and silts tend to be very light in color because they consist of well sorted, quartz-rich sands. Conversely, the silt and clay that cap the laminae tend to be dark because of the small grain size; such fine-grained layers also contain large amounts of macerated and coalified plant material. Grain size and sedimentological differences within the laminae can be detected by optical properties and this facilitates automated image processing. Extraction of laminae thicknesses and harmonic analyses of laminae-thickness series can then be used to test the reasonability of specific environmental processes, such as tidal forcing, that were operative during the formation of these shales. 相似文献
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大型板状交错层理内部沉积物的分异 总被引：2，自引：0，他引：2
本文对取自长江上荆江三八滩大型板状交错层理内部同一细层不同部位的５个样品进行了粒度分析和矿物鉴定，结果表明，在同一细层内沉积物有明显的分异作用。细层中上部以中等粒径、低密度的颗粒为主，分选好。细层的下部和底部主要聚集沉积物的粗尾和细尾部分，因而分选较差。此外，密度较大的矿物亦趋于聚集在细层的底部。沉积物的这种分异主要是因为在沙波运移过程中矿物沿背流面发生重力分异且在背流面附近存在回流所致。大型板状交错层理内部沉积物的这种分异作用对认识其储集性能的层内非均质性有重要的意义 相似文献
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以广西桂林,贵州荔波、茂兰、都匀凯口及云南宣威、泸沽湖等地典型岩溶峰丛-峰林平原、岩溶斜坡和岩溶高原的大量大型石笋纵剖面研究为基础,依据石笋沉积旋回或纹层组的系统测年数据和碳氧同位素系统测试资料,确定石笋沉积间断面上、下的年龄,若以上、下纹层结构构造差异大、构造类型不同、结构构造突变或有间断沉积特征为前提,将上、下纹层的年龄差作为沉积间断时间:差值大,间断时间长,其间若有间歇性停、滴转变,则沉积纹层的测年值是此时段的正常年序;差值小,间断时间短;差值很小,又无宏观异常,为正常的连续沉积。本文从石笋沉积间断标志,间断面上、下的年代异常,间断类型和古气候环境意义,论述石笋沉积间断,阐明石笋纵剖面有丰富的古气候环境信息,是全球气候变化研究的重要领域之一。此外,根据石笋纹层的宏观、微观资料和测年统计,提出了年季和年际的短期性、10年际—万年际的长期性、瞬时性间断类型的分类方案,短期停滴,是常态气候条件下,年旱季或年际干旱停滴,形成年际和季节性沉积间断;长期停滴,是气候环境冷暖周期性变化,略呈小周期的干冷气候间歇性停、滴相间的演变,形成10年际—万年际沉积间断;瞬时性停滴,指地震、掉顶、坍塌等天然或人为事故,碰断石笋,引起瞬时或短暂停滴,形成灾害性沉积间断 相似文献
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北京石花洞石笋中有机质的赋存状态 总被引：2，自引：0，他引：2
选取北京石花洞石笋磨制成光薄片,对它进行了显微镜透射光、反射光和荧光观测.镜下见有两类有机质:一是发黄绿色荧光以富啡酸为主的腐殖酸类有机质,主要赋存在碳酸盐结晶程度差、溶孔发育的暗层或裂隙中;二是粒径小于30 μm的碎屑状固态有机质,它们不发荧光,不均匀地聚集在暗层溶孔周边、暗层与亮层过渡区或亮层内的溶解裂隙中.碎屑状固态有机质的反射率R°为6.72%～6.82%,拉曼光谱为典型石墨类单峰,分析表明,碎屑状固态有机质可能主要来自洞穴上覆土壤或已风化的煤系地层,被较强水流携带进入洞穴,与碳酸钙一同沉积,从而保存在石笋中.石笋微层中暗层与雨期、亮层与干期相对应,石笋中固态有机质的富集带可作为水动力突然变强或"事件"的标志.有机质常为金属离子或金属化合物的载体,不同地区石笋中有机质的研究也将有助于对气候变化多指标研究获得共识. 相似文献
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山东临朐山旺地区中新世山旺组硅藻土极为发育。通过对该地区硅藻土纹层的研究,确定其分类和成因,为进一步确立年纹层的存在、利用其进行高分辨率测年、探讨高频古气候旋回奠定基础。山旺组硅藻土的单层纹层厚度一般为100μm左右。依据纹层的物质成分,单层纹层可分为硅藻纹层、有机纹层和粘土纹层三种类型。各类单层纹层组合成为明暗相间的层偶,层偶厚度一般为100～400μm,常常表现为浅色的硅藻纹层逐渐向深色的粘土纹层或有机质纹层渐变过渡。纹层层偶可分为:薄层硅藻纹层-有机质层偶,厚层藻纹层-有机质层偶,薄层粘土纹层-有机质层偶,厚层粘土纹层-有机质层偶和硅藻纹层-粘土纹层层偶。山旺组硅藻土中不同类型的单层纹层以及层偶的形成主要受控于当时湖盆内粘土物质的沉积速率、硅藻的繁盛程度和有机物质的沉积和保存条件。 相似文献
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洞穴石笋纹(壳)层层组类型研究 总被引：5，自引：0，他引：5
石笋是洞穴碳酸钙沉积的典型滴石类型,也是岩溶记录中最全面、最系统的古气候环境信息载体,随着高分辨率测年技术和测试方法的提高,它在重建古气候环境方面具有重要的意义.石笋沉积纹层的组合、厚度、粒度和层面构造等,是恢复成笋滴水动态及相关古水文条件的物质基础,其中不少古气候环境信息,具强烈直观感,聚集物证、形象地记录于石笋剖面中,易观测研究.通过大量石笋纵剖面观测和系统的同位素组成、微(痕)量元素、特征性纹层的分析研究,证实石笋沉积纹(壳)层具韵律性组合和沉积旋回性及其古气候环境显示.首次提出石笋具叠锥型、叠柱型、叠锥叠柱复(组)合型纹(壳)层组和连续性、旋回性、间断(歇)性叠复纹(壳)层层组类型的沉积构造,并阐述各自的特征、滴流水动态和气候环境演变特征。 相似文献