In-situ Microanalysis of Mg/Ca Ratio in Planktonic Foraminiferal Shells from the Indonesian Seas     

Zhang Peng  Rina Zuraida  Yuan Honglin  Xu Jian  Gao Lianfeng  Zhang Zhenguo  Yang Ce 《地球科学进展》2016,31(5):494-502

Laser Ablation-Inductively Coupled Plasma-Mass Spectrometer (LA-ICP-MS) provides an opportunity for us to perform in-situ microanalysis for depth profiling of elements and trace elements/Calcium ratios in calcite foraminiferal shells. In this study, Globigerinoides ruber shells were investigated with a total of 173 ablating positions from a total of 11 core top sediment samples that retrieved from the Indonesian Seas. The results showed changing compositions of Magnesium and Calcium from the inside to the outside surface for both of intra-test and inter-test. Subsequently, Mg/Ca ratios from the LA-ICP-MS microanalysis were compared with Mg/Ca ratios based on regular analyses, suggesting that LA-ICP-MS microanalysis may provide a comparatively safe and convenient way for investigating Mg/Ca ratio of planktonic foraminiferal shells with considerable reliability and accuracy.  相似文献   

The buckling of GRP hemi-ellipsoidal dome shells under external hydrostatic pressure     

C. T. F. Ross  Bak Hock Huat  Tay Boon Chei  Chai Min Chong  M. D. A. Mackney 《Ocean Engineering》2003,30(5):691-705

The paper reports on a theoretical and an experimental investigation into six GRP hemi-ellipsoidal dome shells, which were tested to destruction under external hydrostatic pressure. All six domes were of oblate shape and of three different aspect ratios. Each aspect ratio consisted of two dome shells, one made from two layers of glass fibre and one made from three layers of glass fibre. The theoretical analysis was via the finite element method where a non-linear theory was used which allowed for both geometrical and material non-linearity. Comparison between theory and experiment was good.  相似文献   

学习实践“改造成矿作用”理论——以滇中砂岩铜矿为例兼论改造作用的上、下限问题   总被引：1，自引：0，他引：1       下载免费PDF全文

冉崇英  胡煜昭  吴鹏  何明勤  陈好寿  王学焜  韩润生 《地学前缘》2010,17(2):35

"改造成矿作用"是涂光炽院士提出的新理论。这一理论有如下基本论点和鲜明特色:矿质来源的广泛性;成矿流体的特殊性;成矿元素的活泼性;改造作用的内生性;断裂构造的主导性;赋矿岩石的多样性;改造矿床的普遍性;成矿作用的独特性与应有地位——矿床分类的四分法。滇中大姚-牟定式砂岩铜矿是典型的沉积-成岩-后生-改造成因。其主要论据与以下要素有关:裂谷成矿背景;矿源层(K、J)、矿源岩(元谋古陆);矿体受地层层位、岩相、岩性控制,其生成与煤系(提供有机质)、盐层(提供卤素)密切相关;矿体形态产状、矿石结构构造、成矿流体性状与水的来源、有机质类型及其作用在不同成矿期、成矿阶段显著不同。从岩石学的名词概念来解读和划分"改造成矿作用"的上限与下限:上限确定在后生作用之后,下限在变生作用之末。  相似文献   

Identification and definition of primary and reworked tephra in Late Glacial and Holocene marine shelf sediments off North Iceland     

Esther Ruth Gudmundsdóttir  Jón Eiríksson  Gudrún Larsen 《第四纪科学杂志》2011,26(6):589-602

Nine tephra layers in marine sediment cores (MD99‐2271 and MD99‐2275) from the North Icelandic shelf, spanning the Late Glacial and the Holocene, have been investigated to evaluate the effectiveness of methods to detect tephra layers in marine environments, to pinpoint the stratigraphic level of the time signal the tephra layers provide, and to discriminate between primary and reworked tephra layers in a marine environment. These nine tephra layers are the Borrobol‐like tephra, Vedde Ash, Askja S tephra, Saksunarvatn ash, and Hekla 5, Hekla 4, Hekla 3, Hekla 1104 and V1477 tephras. The methods used were visual inspection, magnetic susceptibility, X‐ray photography, mineralogical counts, grain size and morphological measurements, and microprobe analysis. The results demonstrate that grain size measurements and mineralogical counts are the most effective methods to detect tephra layers in this environment, revealing all nine tephra layers in question. Definition of the tephra layers revealed a 2–3 cm diffuse upper boundary in eight of the nine tephra layers and 2–3 cm diffuse lower boundary in two tephra layers. Using a multi‐parameter approach the stratigraphic position of a tephra layer was determined where the rate of change of the parameters tested was the greatest compared with background values below the tephra. The first attempt to use grain morphology to distinguish between primary and reworked tephra in a marine environment suggests that this method can be effective in verifying whether a tephra layer is primary or reworked. Morphological measurements and microprobe analyses in combination with other methods can be used to identify primary tephra layers securely. The study shows that there is a need to apply a combination of methods to detect, define (the time signal) and discriminate between primary and reworked tephra in marine environments. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

河南熊耳山蚀变断层岩型金矿床成因的地质及地球化学特征   总被引：4，自引：1，他引：4  

邵世才  汪东坡 《地质论评》1994,40(6):520-525

本文通过太华群，熊耳群和燕山期花岗岩等地质体的含金性评价，认为熊耳山蚀变断层岩型金矿床的的金等成矿元素大多来自太华群，且太华群是主要的矿源层，对矿床的硫，铅，氢，氧和碳同位素的研究表明，硫，铅及碳等成矿物质源于太华群，而成矿流体则主要为大气降水，可能有少量岩浆水的加入。结合晚太古代至元古宙的区域变质作用，燕山期的构造－岩浆热事件和成矿时代，作者认为该类金矿床是一种复杂的改造型矿床，燕山期的构造－岩  相似文献   

辽东－吉南地区早元古代硼镁石型硼矿床地质特征及矿床成因   总被引：11，自引：4，他引：11  

刘敬党 《化工矿产地质》1996,(3)

通过对辽东－吉南硼矿床地质特征、矿床地球化学及Ｏ、Ｃ、Ｂ同位素特征的研究，结合数学地质方法分析认为辽东－吉南地区早元古代硼矿的成矿作用可分为沉积成岩成矿和变质－混合岩化改造成矿这两个主要成矿期。矿床成因类型为沉积变质改造型  相似文献   

防雹作业用弹量的计算   总被引：6，自引：1，他引：6  

王雨增  刘新元 《气象》1996,22(6):29-31

利用各地冰雹资料以及冰雹从０℃层等温线到地面的降落过程中的融化情况，并参考各地防雹作业的实际用弹量，提出雹源含水量的近似计算方法，推导出每个炮点一次防雹作业用弹量的计算公式。  相似文献   

单层柱面网壳的粘滞阻尼器减振分析   总被引：6，自引：0，他引：6  

范峰  沈世钊 《世界地震工程》2003,19(2):27-32

采用粘滞阻尼器减振系统对单层柱面网壳的减振效果进行了较为系统的分析，分别考虑了阻尼系数C0、结构自身阻尼比ζ、屋面质量和结构自身刚度对结构减振系数δ的影响，同时考察了设置阻尼器的数目以及阻尼器的位置的影响。通过较大规模参数化分析，基本了解了粘滞阻尼器减振系统在单层柱面网壳中的减振规律。  相似文献   

黄土中蜗牛壳Mn^2＋的EPR研究及其古气候意义   总被引：2，自引：0，他引：2  

盛雪芬  陈骏  季峻峰  眭云霞 《高校地质学报》2002,8(1):40-45

对黄土高原陕西省洛川和甘肃省西峰剖面中黄土－古土壤层中的蜗牛壳进行了EPR波谱分析，同时对洛川地区的现代蜗牛壳也进行了测定。结果显示：（1）不同种类的蜗牛壳具有相近的EPR信号强度，表明不同种类的蜗牛对Mn^2+的吸收没有差异性。（2）黄土层中蜗牛壳的EPR信号强度远大于占土壤中的，即黄土中蜗牛壳所含的Mn^2+远大于古土壤中的蜗牛壳的Mn^2+的含量，说明前者生活在比较还原的条件下，后者形成环境的氧化性较高。因此本认为为蜗牛壳中Mn^2+的含量可反映其生长环境中Mn^2+的含量和氧化还原条件，对古气候的重建具有重要意义。  相似文献   

Marine reservoir correction for the Pacific coast of central Japan using C ages of marine mollusks uplifted during historical earthquakes     

Masanobu Shishikura  Tomoo Echigo  Heitaro Kaneda 《Quaternary Research》2007,67(2):286-291

In this study we utilize marine shell samples from two levels of historically uplifted sessile mollusk assemblages and raised wave-cut benches to evaluate the marine reservoir correction (ΔR) for the Pacific coast of central Japan. Elevation measurements of the uplifted marine shells indicate that the lower assemblage emerged during the 1923 Taisho Kanto earthquake (M7.9), whereas uplift of the upper assemblage is most likely but less confidently ascribed to the 1703 Genroku Kanto earthquake (M8.2). Radiocarbon dating of carefully selected samples from the upper and lower assemblages yielded very similar ΔR values of 82 ± 33 and 77 ± 32 yr, respectively. We regard the former ΔR value as a representative and more reliable value given the uncertainty in correlation of the upper assemblage with the 1703 earthquake. This result is consistent with previously reported ΔR values for the Pacific coast of south-central Japan and areas around the Sea of Japan that are influenced by warm ocean currents. Radiocarbon dating of coseismically uplifted shells can aid in estimating marine reservoir ages in the tectonically active Japan Islands.  相似文献