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Автор(ы):Reyment A.R., Savazi E.
Издание:Elsevier, 1999 г., 285 стр., ISBN: 0-444-82568-1
Язык(и)Английский
Aspects of multivariate statistical analysis in geology

Multivariate statistical methods have become commonplace in the Earth Sciences. What was once an exclusive area of activity is now within the reach of Everyman, owing to the ubiquitousness of mini-computers and the ready availability of software for doing the computing. In the days when one was required to do one's own programming, it was necessary to acquire considerable proficiency in linear algebra and one or more programming languages. Today, the vast majority of the people who use multivariate methods to analyse geological data have little or no idea of the matrix operations underlying a particular method, nor, for that matter, what the program is actually supposed to be doing. This situation can be both good and bad. It can do no harm if everything goes according to schedule, the program being used is competently constructed, which, alas, is far from being the general case, and there are no strong deviations from standard statistical theory in the data under examination. It is bad if the data do not fit the theoretical requirements of a particular method and even worse if the method of computation used is inappropriate. It is an inescapable and sad fact of life that much geological and biological material deviates in some manner or other from the theoretical requirements of a multivariate statistical procedure. The immediate relevance of this observation is that there are many sources of error in doing an analysis of geological data by means of standard statistical software.

Том 17, Выпуск 3
Издание:Stratigraphy and Geological Correlation, 2009 г., 16 стр.
Язык(и)Английский
Assembly and Breakup of Rodinia (Some Results of IGCP Project 440)

The principal results of project 440 “Assembly and Breakup of Rodinia” of the International Geological Correlation Programme (IGCP) are reviewed in this work. A map of that supercontinent compiled using geological and paleomagnetic data describes global paleogeography 900 Ma ago. The assembly of Rodinia, which comprised most of Precambrian continental blocks, lasted ca. 400 m.y. (from 1300 to 900 Ma). Its breakup presumably triggered by mantle superplume took place between 830 and 650 Ma. The correlation between tectonic events in different continental blocks is considered. Some problems concerning the Rodinia reconstruction and history, e.g., the slow growth of juvenile crust and effects of mantle-plume events during the amalgamation period and of glaciations at the breakup time, are discussed. The latter caused changes in the biosphere and climate, whereas postglacial periods stimulated progress in biota evolution

Выпуск 38
Издание:Палеонтологический институт РАН, Москва, 2002 г., 75 стр.
Язык(и)Английский
Astrovioidea: a new superorder of paleozoic cephalopods

A new superorder of Paleozoic eclochochlian eephalopods, Aslrovioidea superordo nov., is designated. A distinctive feature of this superorder is that the soft eameral tissue enters the siphon cavity and secrets calcareous eameral deposits. This resulted in the destruction of the connecting rings that previously constituted, in conjunction with the septal necks, the compound wall of the siphon. In early (Ordovician) representatives of this superorder, the soft eameral tissue passed through the siphon to destroy, either partially or completely, the connecting rings and to progress occasionally along the internal surface of those rings that remained unde-stroyed as far as several chambers (the order Lituilida Starobogalov, 1983).

Редактор(ы):Thompson A.J.B., Thompson J.F.H., Dunne K.P.E.
Издание:Mineral deposits division, 1996 г., 119 стр., ISBN: 978-0919216594
Язык(и)Английский
Atlas of alteration. A field and petrographic guide to hydrothermal alteration minerals

Secondary alteration of rocks and their contained minerals is common in nature. Alteration reflects the interaction of fluid, typically dominated by water, with rock at temperatures that range from warm (< 100°C) to hot (>500°C). For geologists who wish to study the primary mineralogy and chemistry of rocks, alteration is a nuisance to be avoided. Alteration mineralogy, however, documents the post-formation history of the rock, information that has practical implications. In particular, alteration is ubiquitous in and around hydrothermal mineral deposits. The distribution and mineralogy of this alteration relates to the hydrothermal environment, and hence, the type of mineral deposit. More importantly for mineral exploration, hydrothermal alteration around mineral deposits commonly forms halos that provide a target which is much larger than the deposit itself. The mineralogy and in some environments the chemical composition of the alteration provide an indication of the proximity of mineralization, or in the ideal case, a vector towards mineralization. Interpretation of alteration is, therefore, a routine part of exploration for hydrothermal mineral deposits. Similarly, as a product of geothermal activity, the mineralogy of hydrothermal alteration provides information on reservoir and fluid characteristics, and the evolution of the geothermal system. These data are used in conjunction with other information to evaluate potential geothermal resources.

Издание:148 стр.
Язык(и)Английский
Atlas of Igneous Rocks and their Textures

Atlas of igneous rocks and their textures A companion volume to the Atlas of Rock-forming Minerals in Thin Section, this full-colour handbook is designed to be used as a laboratory manual both by elementary students of earth sciences undertaking a study of igneous rocks in thin section under the microscope, and by more advanced students and teachers as a reference work. The book is divided into two parts — Part One is devoted to photographs of many of the common textures found in igneous rocks with brief descriptions accompanying each photograph. Part Two illustrates the appearance of examples of some sixty of the commonest (and a few not so common) igneous rock types; each photograph is accompanied by a brief description of the field of view shown. Nearly 300 full-colour photographs are included, and in many cases the same view is shown both in plane-polarized light and under crossed polars. A brief account of how thin sections can be prepared is included as an appendix. It is believed that the amateur geologist using these instructions will be able to make his own thin sections and, with the aid of a relatively simple microscope, enjoy the study of rocks in thin section.

Источник:Интернет
Выпуск 102
Издание:Economic geology, 2007 г., 27 стр.
Язык(и)Английский
Bald mountain gold mining district, Nevada: a Jurassic reduced intrusion-related gold system

The Bald Mountain mining district has produced about 2 million ounces (Moz) of Au. Geologic mapping, field relationships, geochemical data, petrographic observations, fluid inclusion characteristics, and Pb, S, O, and H isotope data indicate that Au mineralization was associated with a reduced Jurassic intrusion. Gold deposits are localized within and surrounding a Jurassic (159 Ma) quartz monzonite porphyry pluton and dike complex that intrudes Cambrian to Mississippian carbonate and clastic rocks. The pluton, associated dikes, and Au mineralization were controlled by a crustal-scale northwest-trending structure named the Bida trend. Gold deposits are localized by fracture networks in the pluton and the contact metamorphic aureole, dike margins, high-angle faults, and certain strata or shale-limestone contacts in sedimentary rocks. Gold mineralization was accompanied by silicification and phyllic alteration, ±argillic alteration at shallow levels. Although Au is typically present throughout, the system exhibits a classic concentric geochemical zonation pattern with Mo, W, Bi, and Cu near the center, Ag, Pb, and Zn at intermediate distances, and As and Sb peripheral to the intrusion. Near the center of the system, micron-sized native Au occurs with base metal sulfides and sulfosalts. In peripheral deposits and in later stages of mineralization, Au is typically submicron in size and resides in pyrite or arsenopyrite. Electron microprobe and laser ablation ICP-MS analyses show that arsenopyrite, pyrite, and Bi sulfide minerals contain 10s to 1,000s of ppm Au. Ore-forming fluids were aqueous and carbonic at deep levels and episodically hypersaline at shallow levels due to boiling. The isotopic compositions of H and O in quartz and sericite and S and Pb in sulfides are indicative of magmatic ore fluids with sedimentary sulfur. Together, the evidence suggests that Au was introduced by reduced S-bearing magmatic fluids derived from a reduced intrusion. The reduced character of the intrusion was caused by assimilation of carbonaceous sedimentary rocks.

Tertiary faults dismember the area and drop down the upper part of the mineralizing system to the west. The abundant and widespread kaolinite in oxide ores is relatively disordered (1A polytype) and has δD and δ18O values suggestive of a supergene origin. The deep weathering and oxidation of the ores associated with exhumation made them amenable to open-pit mining and processing using cyanide heap leach methods.

Автор(ы):Park A.F.
Издание:Elsevier, 1981 г., 5 стр.
Язык(и)Русский
Basement gneiss domes in the Svecokarelides of eastern Finland: discussion

A recent paper in this journal (J.-P. Brim. The cluster-ridge pattern of mantled gneiss domes in eastern Finland: evidence for large-scale gravitational instability of the Proterozoic crust. Earth Planet. Sci. Lett. 47 (1980) 441-449) resurrects Eskola's [I] concept of the mantled gneiss dome in the early Proterozoic Svecokarelian fold bell of Finland. The author cites amongst others, the Kuopio, Juojarvi, Maarianvaara. Kontiolahti, Liperi, Oravisalo and Sotkuma domes (see Fig. 1) as examples of the diapiric upwelling of lower-density, granitic Archaean basement rocks, into more dense, overlying Karelian metasedimentary formations. The distribution of these basement structures is interpreted as reflecting a periodicity. which by analogy with the centrifuge experiments of Ramberg [2], is a function of the interlayer density contrast and the layer thicknesses.

Автор(ы):Stadtler A.
Издание:Ruhr-universitat Bochum, Ruhr, 1998 г., 127 стр.
Язык(и)Немецкий
Bochumer geologische und geotchnische. Heft 49 (1998). Der bentheimer sandstein (Valangin, NW-Deutschland). Eine palokologische und sequenzstratigraphische analyse

This thesis represents one part of the European project “Geological characterisation of shallow marine sands for reservoir modelling and high resolution stratigraphic analysis”, which was established to study shallow marine sands with respect to reservoir properties. The research was focused on the micropalaeontological characterisation of mudstone and source rock successions and the nature, origin and reservoir characteristics of the Bentheim Sandstone in the Lower Saxony Basin.

Редактор(ы):Almeras Y.
Издание:Imprimerie Rhodanienne, Lyon, 1964 г., 154 стр.
Язык(и)Французский
Brachiopodes du lias et du dogger

Lorsque l'on se propose d'étudier les Brachiopodes du Lias et du Dogger , on est surpris par le grand nombre d'espèces créées aussi bien que par le nombre d'ouvrages décrivant des Brachiopodes . Devant un sujet aussi vaste , devant des efforts aussi dispersés , il m'a paru opportun de faire le point : dénombrer les espèces nouvelles d'après les recherches bibliographiques , mettre sur fiches méca-nalytiques leurs diagnoses originales , établir les listes synonymiques critiques est le premier travail à effectuer et il a pour résultat l'obtention de la durée moyenne  de  vie  pour chaque  espèce   (répartition stratigraphique) <...>

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