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Автор(ы):Park A.F.
Издание:Elsevier, 1981 г., 5 стр.
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.
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.
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) <...>

Автор(ы):Almeras Y.
Издание:Centre des Sciences de la Terre, Lyon, 1996 г., 196 стр., ISBN: 5-85454-088-3
Brachiopodes toarciens et aaleniens de la tethys nord-occidentale

The recent accessibility of the collection of Dumortier, the complementary collects in the Bas-Beaujolais and in the Southern Provence, allow us to present the paleontological revision of the Toarcian and Lower Aalenian brachiopods of the Rhone basin (Bas-Beaujolais, Mont d'Or Lyonnais, La Verpilliere - Saint Quentin-Fallavier and Southern Provence). Then, the systematics of Dumortier is reactualized. The different species are again located in a more precised strati graphical framework. So, it is possible to deduce the biostratigraphy of Toarcian and Lower Aalenian brachiopods and then, to verify the value of the zonal succession established before (Almeras & ah, 1991)

Издание:Blackwell science Ltd, Oxford, 1990 г., 482 стр., ISBN: 0-632-01472-5
Carbonate sedimentary

ТЬе intention of this book is to provide а detai!ed synthesis of the enormous body of research which has Ьееп published оп carbonate sediments and rocks. Such rocks аге worthy of attention for severa! reasons. ТЬеу аге vo!umetrically а most signifcant part of the geo!ogica! record and possess тисЬ of the fossil гес-ord of !ife оп this p!anet. Most importantly they contain at !east 40% of the wor!d's known hydroсагЬоп reserves. ТЬеу a!so р!ау host to base meta! deposits and groundwater resources, and аге raw materia!s for the construction and chemica! industries. No other rock type is as economically important.

Автор(ы):Чернышев Б.И.
Carbonicola, Anthracomya и Najadites Донецкого бассейна

Настоящая работа была закончена еще в 1924 г. В течение четырех лет я не мог, по различным соображениям технического характера, опубликовать ее. Такая задержка меня весьма радует, так как за это время я имел возможность обменяться коллекциями и письмами с профессором университета в Лилле P. Pruvost и тем самым подвергнул двойному контролю свои определения: с одной стороны, сравнив непосредственно свои образцы с французскими, с другой стороны—профессор P. Pruvost, просмотрев посланную ему коллекцию, указал на полное тождество донецких образцов с французскими и английскими. Другое обстоятельство, весьма благоприятное для моей работы, было то, что в течение четырех лет, постоянно работая в Донецком бассейне, я мог подвергать контролю те выводы, какие были мною сделаны в главах II и III. Такой контроль дал возможность, с одной стороны, подтвердить выводы и исправить мелкие недочеты и неправильные определения в тех толщах, которые подвергались наблюдению, с другой стороны—позволил расширить эти наблюдения на более обильном материале и, наконец, с третьей стороны—при таких наблюдениях часто удавалось разрешать некоторые неясные вопросы в геологии бассейна.

Выпуск 90
Автор(ы):Arthur W.Rose, Carl A.Kuehn
Издание:Economic geology, 1995 г., 20 стр.
Carlin gold deposits, Nevada: origin in a deep zone of mixing between normally pressured and overpressured fluids

Gold mineralization at Carlin is clearly younger than hydrocarbon maturation (pre-Cretaceous) and felsic dike intrusion (Cretaceous), and older than deep oxidation (late Tertiary). Within the episode of gold mineralization, the main gold ore (MGO) stage and late gold ore (LGO) stage are distinguished paragenetically, wi-th a variety of vein and mineralization types in each. MGO stage fluids contained 5 to 10 mole percent COa, appreciable H2S, and 3 ± 1 wt percent NaCl equiv. At least portions of MGO stage mineralization were characterized by two-phase boiling (COa exsolution) at 215° ± 30°C and 800 ± 400 bars. In contrast, LGO stage fluids were gas poor with salinities <1.5 wt percent NaCl equiv and record only nonboiling conditions. MGO stage fluids had 518Oh2o values of 5 to 9 per mil, whereas LGO stage fluids resembled unevolved meteoric water with 518Oh2o values < —3 per mil.

From the MGO stage to the LGO stage, calcite 5180 values shifted from near whole-rock values of 12 ± 3 per mil to around 0 ± 1 per mil as LGO stage fluids flooded the system. Jasperoids also record a large range (9-22%o) in 518Oh2o values. These data indicate the involvement of two very different fluids in ore deposition. Because MGO and LGO stage features are closely associated spatially with each other and with Au, As, Sb, Hg, and other ore elements, both fluids are believed to have both been present during most stages of ore deposition.

At pressures of 80 to 85 percent lithostatic, depths of 3.8 ± 1.9 km are required to accommodate the 800 ± 400 bars of pressure recorded in MGO stage fluid inclusions. Carlin, therefore, is not an epi-thermal or hot spring deposit. Carbon dioxide in gas-rich MGO stage fluids may have originated either directly from buried intrusions or their contact aureoles, or from low-grade regional metamorphism at depth. The water may have been originally meteoric, and Au may be magmatic or derived from leaching of deep metamorphic or sedimentary rocks. Ore deposition appears to have occurred in zones of throttling at a pressure seal between normally pressured and overpressured regimes, where fluids experienced a change from near-lithostatic to hydrostatic conditions. Such pressure seals are common in deep sedimentary basins and may be a key to highly localized gold deposition. Mixing of two fluids and interaction with host rocks along thin permeable bioclastic horizons are believed to have been the major factors in depositing ore.


Издание:Economic geology, 2005 г., 34 стр.
Carlin-type gold deposits in Nevada: critical geologic characteristics and viable models

Carlin-type Au deposits in Nevada have huge Au endowments that have made the state, and the United States, one of the leading Au producers in the world. Forty years of mining and numerous studies have provided a detailed geologic picture of the deposits, yet a comprehensive and widely accepted genetic model remains elusive. The genesis of the deposits has been difficult to determine owing to difficulties in identifying and analyzing the fine-grained, volumetrically minor, and common ore and gangue minerals, and because of postore weathering and oxidation. In addition, other approximately contemporaneous precious metal deposits have overprinted, or are overprinted by, Carlin-type mineralization.

Выпуск 1
Автор(ы):Mehrtens M.B.
Издание:Economic geology, 1986 г., 5 стр.
Case history and problem 1: the Tonkin Springs gold mining district, Nevada, U.S.A.

Geochemical techniques played a major role in exploration of the Tonkin Springs district and ultimately led to discovery of economically significant bodies of gold mineralization. Using some of the information obtained during the exploration program, it is possible to review the geochemical environment, secondary dispersion processes and survey techniques used successfully in this part of Nevada.

The Tonkin Springs district is located in west-central Eureka County, Nevada, within the Simpson Park Range approximately 65 km northwest of the town of Eureka (Figure 7.1). Topography is typical of the Basin and Range structural province being characterized by long narrow valleys and north easterly trending mountain ranges with elevations varying between 1,700 and 3,100 m. Precipitation is in the order of 400 mm per year, the major portion of which occurs in the higher elevations during winter and spring. Soils are light brown to brown desert soils of residual origin in locations above the gravel-filled valleys and pediments. Vegetation consists of sagebrush and sparse grass in the valleys with juniper, pinyon and mountain mahogany in the higher country.