An application of cluster analysis in mineral exploration     

P. L. Collyer  D. F. Merriam 《Mathematical Geology》1973,5(3):213-223

This paper presents a technique for evaluating the similarity of ore deposits utilizing several geological variables. Information on tungsten mines in North America, taken from published literature, was used for a cluster analysis to group samples according to their similarity based on a simple matching coefficient. It was possible to interpret and evaluate different ore environments that clustered according to age, mineralogy, and other variables. Cluster analysis may be important in mineral exploration where considerable amounts of data are available for analysis. Subtle relationships that might be overlooked because the data are too voluminous can be isolated using this technique. It also can be used to establish exploration priority in unknown areas on the basis of similarity to known metallogenetic provinces.  相似文献   

Cyclocrinus, an enigmatic Jurassic–Cretaceous crinoid     

Hans Hess 《Swiss Journal of Geoscience》2008,101(2):465-481

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Anisian ammonoids from Qingyan, southwestern China: biostratigraphical implications for the age of the Qingyan Formation     

Frank Stiller  Hugo Bucher 《Swiss Journal of Geoscience》2008,101(2):547-562

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DMSP and DMS in the Northwest Atlantic: Late-summer distributions,production rates and sea-air fluxes     

Michael G. Scarratt  Maurice Levasseur  Sonia Michaud  Sylvie Roy 《Aquatic Sciences - Research Across Boundaries》2007,69(3):292-304

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Material referred to Megalosaurus (Dinosauria: Theropoda) from the Middle Jurassic of Stonesfield, Oxfordshire, England: one taxon or two?     

Julia J. Day 《Proceedings of the Geologists' Association. Geologists' Association》2004,115(4):359-366

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浮游藻类三个常见属(颤藻属、直链硅藻属和针杆藻属)学名变更的解释   总被引：1，自引：3，他引：1       下载免费PDF全文

陈宇炜  李朋富  MartinDOKULIL 《湖泊科学》2003,15(1):85-94

根据近年来国外文献所涉及的藻类分类学研究进展，着重解释了蓝藻门的颤藻属和硅藻门的直链硅藻属和针杆藻属的一些浮游种类的学名变更情况，同时介绍了国际上最新的蓝藻门颤藻目和硅藻门的分类概况．根据Anagnostidis和Komfirek的分类，原颤藻属的大部分浮游种类进入了新属『浮游蓝丝藻属](Planktothrix)，其他种类则分别属于[湖生蓝丝藻属](Limnothrix)、胶鞘藻属(Phormidium)和现在的颤藻属(Oscillatoria)等多个颤藻目的类别．根据Krammer和Lange-Bertalot的分类，原直链硅藻属的浮游种类进入了新属[浮生直链藻属](Aularoseira)，另外的种类归属于Orthoseira、Ellerbeckia和现在的直链硅藻属(Melosira)等硅藻类别中：原针杆藻属的浮游种类并入脆杆藻属(Fragilaria)，其他种类进入菱形藻属(Nitzschia)、双尖菱板藻属(Hantzschia)和现在的针杆藻属(Synedra)中．  相似文献   

Taxonomy, facies relationships and palaeobiology of bakevelliid bivalves from the Lower Cretaceous of west-central Argentina     

Darío Gustavo Lazo   《Cretaceous Research》2003,24(6):765

Cretaceous bakevelliids in Argentina are restricted to the Lower Cretaceous. They are recorded in shallow marine deposits in two Mesozoic basins located in the Andes foothills in Patagonia. In the Austral Basin (44°–55°S) there is only one genus, Gervillella, represented by a single specimen from the Barremian. In the Neuquén Basin (30°–40°S) two genera, Gervillaria and Gervillella, occur, ranging from the Berriasian to the Lower Barremian. In the Pilmatué Member of the Agrio Formation two species are identified: Gervillaria alatior (Imlay) and Gervillella aviculoides (J. Sowerby). The former is also recorded in Mexico while the latter is more widespread, occurring in Europe, Asia, and Africa. In the Bajada del Agrio section they come from eight tabular shell beds located near and on top of shallowing-upwards cycles. They were abundant only in four of these levels. These shell beds are interpreted as having been deposited in the mid-ramp (middle of cycles), and upper mid-ramp (top of cycles). A functional analysis of shells revealed two life habits: epibyssate and endobyssate.  相似文献   

1999年9月21日台湾集集地震的震源参数综合判定     

陈祥熊 《福建地震》2005,(4)

本文利用半经验、半理论的方法对世界各主要地震汇集和研究机构所给出的集集主震基本震源参数进行了综合计算和评定。根据这些参数重新计算了集集主震的标量地震矩、破裂面积、应力降等。根据这些参数之间的内在联系,从地震分类学的角度,判定集集地震是发生于板块边缘的大地震。可供研究台湾岛上地震活动性以及台湾地区板块构造演化问题参考。  相似文献   

Nematode species distribution patterns at the Håkon Mosby Mud Volcano (Norwegian Sea)     

Daria Portnova  Vadim Mokievsky  Thomas Soltwedel 《Marine Ecology》2011,32(1):24-41

The Håkon Mosby Mud Volcano (HMMV) is a methane seep that is densely populated by the bacteria Beggiatoa spp. as well as by tubeworms of the Family Siboglinidae. Analyses of samples from seven stations located in five different habitats (bare sediments, bacterial mats, siboglinid fields, sediments with small patches of siboglinids and areas of ‘normal’ sea floor) revealed differences in the density and species‐level diversity of nematode communities. Total densities increased from stations inside the mud volcano and on its rim towards the ‘normal’ areas outside the volcano. Nematode species diversity was similar in samples from the siboglinid fields and the bare HMMV sediments. However, the sediment with patches of siboglinids collected outside the volcano was characterised by a diverse nematode community comprising 47 species, whereas the control sediments without siboglinids yielded only 27 species. The nematode assemblage at the bacterial mat site included only two identified species, Halomonhystera disjuncta and Sabatieria ornata, with H. disjuncta being strongly dominant. Terschellingia distlamphida, S. ornata and Aponema ninae dominated nematode communities at the siboglinid fields and in bare HMMV sediments. Species dominating at stations inside the caldera were found in comparable low densities in the sediment with siboglinid patches collected outside the volcano, but were missing in the background samples, where species of Endeolophos, Acantholaimus and Desmoscolex were dominant. Species diversity generally decreased with sediment depth. A subsurface‐dwelling nematode community was observed in the siboglinid fields and the bare sediments. Background sediments showed a sharp decline with 18–20 species at 0–2 cm versus three species at 3–5 cm sediment depth. The trophic composition of the nematode fauna at the HMMV showed a prevalence of deposit feeders at almost all stations, whereas background sediments exhibited a uniform distribution of non‐selective and selective deposit feeders and epistrate feeders. The high percentage of deposit feeders inside the mud volcano could be related to the grain‐size distribution and the significantly higher bacterial biomass compared to the control sediments.  相似文献   

中国海鞭毛藻新纪录目柄钟藻目一新纪录梨形假柄钟藻     

殷明焱  胡晓燕 《海洋科学》2011,35(11):69-72

对从青岛沿海分离的一株鞭毛藻进行了显微和超微结构研究, 发现其为中国海一新纪录种——梨形柄钟藻（Pseudopedinella pyriforme Carter）。该藻细胞为辐射对称结构; 具6 个色素体, 色素体内侧具蛋白核, 与细胞核相邻; 线粒体具管状嵴; 细胞前端具一根鞭毛, 鞭毛向一侧加宽形成翼; 尾部具一与...  相似文献