Geochemistry and hydrothermal alteration of the Kern Mountains plutonic complex,White Pine County,Nevada and Juab County,Utah     

Usman A. Sayeed  Samuel B. Treves  Robert B. Nelson 《International Journal of Earth Sciences》1977,66(1):614-644

The Kern Mountains plutonic complex is composed of multiple intrusions referred as the Cove, Tungstonia and Hoodoo Canyon plutons, whose emplacement was structurally controlled. The plutons are members of the calc-alcaline granite series, leucogranite type that are relatively alkali rich. The complex is of epizone (4–10 km) and was emplaced during Jurassic time into the carbonates and quartzite of Paleozoic age. Trace and major element data indicate that the complex was derived from the partial melting of rocks similar to Canadian Shield rocks. Analysis of variance of chemical data suggets that hydrothermal solutions carried K₂O, Na₂O and SiO₂ and raised the levels of original oxides in the plutons. Hydrothermal activity is evidenced by the occurrence of second generation muscovite, potassium feldspar and quartz in the complex and tungsten and sulphide mineralization in the area.

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Zusammenfassung Der plutonische Komplex des Kerngebirges besteht aus mehrfachen Instrusionen, genannt Cove-, Tungstonia- und Hoodoo Canyon-Pluton, deren Platznahme tektonisch kontrolliert wurde. Die plutonischen Gesteine gehören zu den Kalkalkaligraniten; sie sind leucogranitisch und damit ziemlich alkalireich. Der Komplex ist epizonal (4–10 km), er drang während des Jura in die Karbonate und Quarzite des Paläozoikums ein. Spuren- und Hauptelementmeßwerte zeigen an, daß der Komplex von aufgeschmolzenen Gesteinen abgeleitet werden kann, die den Gesteinen des Kanadischen Schildes ähneln. Die Analyse der Variation von chemischen Meßwerten deutet an, daß hydrothermale Lösungen K₂O, Na₂O und SiO₂ enthielten, die das Niveau der ursprünglichen Oxide in den plutonischen Gesteinen erhöhten. Die hydrothermale Tätigkeit wird durch das Vorhandensein von Muskowit, Kaliunifeldspat und Quartz der zweiten Generation innerhalb des Komplexes und durch Wolfram- und Sulfidmineralisation in der Umgebung bewiesen.

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Résumé L'ensemble plutonique des montagnes de Kern, consiste en de nombreuses intrusions dénommées plutons du »Cove«, de »Tungstonia«, et du »Hoodoo Canyon« dont la mise en place a été tectoniquement controlée. Ces plutons font partie de la série granitique calco-alkaline; ce sont des leucogranites relativement riches en alcali. L'ensemble est épizonal (4–10 km), et s'est mis en place au cours du Jurassique dans des Calcaires et quartzites d'âge paléozoique. Les données analytiques relatives aux élements majeurs et en trace indiquent que cet ensemble peut provenir de la fusion partielle de roches similaires à celles du Bouclier Canadien.L'analyse de la variation des données chimiques suggère aussi que l'enrichissement de ces plutons en K₂O, Na₂O, et SiO₂ s'est fait à partir de solutions minéralisantes hydrothermales, comme en témoignent non seulement la présence d'une deuxième génération de muscovite, de feldspath potassique et de quartz, mais aussi par la mineralisation en tungstène et en minerais sulfurés à leur voisinage.

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, Cove, Tungstonia Hoodoo Canyon, . - ; , , . (4–10 ); . - , , . , K₂O, Na₂O SiO₂, . , .

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Fatty acids and Pb-210 geochronology of a sediment core from Buzzards Bay,Massachusetts     

John W Farrington  Susan M Henrichs  Robert Anderson 《Geochimica et cosmochimica acta》1977,41(2):289-296

Four sections of a Pb-210 dated core of 62 cm length from Buzzards Bay, Massachusetts, were analyzed for fatty acids. A comparison of fatty acids extracted by Soxhlet extraction (unbound fatty acids) with fatty acids extracted by subsequent saponification extraction of the same sample (bound fatty acids) showed the former did not undergo diagenetic loss any faster than the latter. However, compositional differences between bound and unbound fatty acids were apparent in the top section of 1–2 cm and were less apparent in the 54–58 cm section. At least 14% of the bound fatty acids are esterified to non-solvent extractable material. The net conversion of fatty acids to other compounds is 32 μ/g dry weight sediment over the first 30 yr after deposition.  相似文献   

Radiocarbon dates and late-Quaternary stratigraphy from Mamontova Gora,unglaciated central Yakutia,Siberia, U.S.S.R.     

Troy L. Péwé  André Journaux  Robert Stuckenrath 《Quaternary Research》1977,8(1):51-63

A fine exposure of perennially frozen ice-rich silt and associated flora and vertebrate fauna of late-Quaternary age exists at Mamontova Gora along the Aldan River in central Yakutia, Siberia, U.S.S.R. The silt deposit caps a 50-m-high terrace and consists of three units. An upper layer 1–2 m thick overlies a 10–15-m-thick brownish to black silt layer. The lower silt layer is greenish to gray and about 15 m thick. All the silt is well sorted with 60% of the particles falling between 0.005 and 0.5 mm in diameter and is generally chemically and mineralogically homogeneous. The middle unit contains may extinct vertebrate mammal remains and ice wedges. The lower unit contains little vegetation and no ice wedges. The silt is widespread and exists as a loamy blanket on terraces at various elevations on both sides of the lower Aldan River. The origin of the silt blanket of late-Quaternary age in central Yakutia has long been controversial. Various hypotheses have been suggested, including lacustrine and alluvial, as well as frost-action origins. It is sometimes referred to as loess-like loam. Péwé believes the silt at Mamontova Gora is loess, some of which has been retransported very short distances by water. The silt probably was blown from wide, braided, unvegetated flood plains of rivers draining nearby glaciers. The silt deposits are late Quaternary in age and probably associated with the Maximum glaciation (Samarov) and Sartan and Syryan glaciations of Wisconsinan age. On the basis of biostratigraphy, 10 radiocarbon dates, and their relation to the nearby glacial record, it is felt that the upper unit at Mamontova Gora is Holocene and the middle unit is Wisconsinan. The youngest date available from the middle unit at this particular location is 26,000 years. Dates greater than 56,000 years were obtained in the lower part of the middle unit. The lower unit is definitely beyond the range of radiocarbon dating and probably is older than the last interglacial. The sediment, fauna, ice wedges, stratigraphy, and age of perennially frozen slit deposits in central Alaska are remarkably similar to those of the deposits exposed in central Yakutia. Both areas consist of unglaciated rolling lowlands and river terraces surrounded by high mountains that were extensively glaciated in Pleistocene time. The glaciers extended from the high mountains to the edges of the ranges. In both regions, extensively braided, silt-charged rivers drained the mountains and flowed through the lowlands on their way to the sea. It follows that there should be a similar late-Quaternary history.  相似文献   

Mercury in some granitoid rocks of the yukon and its relation to gold-tungsten mineralization     

Robert G. Garrett 《Journal of Geochemical Exploration》1974,3(3):277-289

Data for the mean mercury contents of some granitoid rocks of the Yukon are presented. A correlation of high mercury content with plutons postulated to be the sources, or genetically related to the sources, of the alluvial gold deposits of the McQuesten area is established. In addition a relation is indicated between high mercury content in one intrusion and high content in the Palaeozoic shale host rock. A limited amount of data is presented on the mercury content of the Proterozoic and Palaeozoic rocks of the sampled area.  相似文献   

Surface history of some Apollo 17 lunar soils     

Robert L. Fleischer  Howard R. Hart 《Geochimica et cosmochimica acta》1974,38(10):1615-1623

Cosmic ray track densities in Apollo 17 soil samples are used to infer surface exposure times of soils from a trench at Van Serg Crater, from on and near a boulder at Camelot Crater, and from the position of the heat flow and neutron flux experiments (the ALSEP site). The topmost 2 cm of soil at Van Serg was exposed for 11 m.y., the top cm at Camelot for 36 m.y. A layering chronology and average deposition rate are proposed for the trench. For all soils the median track densities imply predispositional irradiation in the top 15 cm of the lunar surface for times that were long compared with the actual residence in the stratigraphic positions from which the soils were collected. Van Serg crater is inferred to have been formed approximately 24 m.y. ago.  相似文献   

Rb-Sr age of lunar igneous rocks 62295 and 14310     

Robert K. Mark  Chin-Nan Lee-Hu  George W. Wetherill 《Geochimica et cosmochimica acta》1974,38(10):1643-1648

We report an age of crystallization for spinel-troctolite (VHA basalt) 62295 of 4.00 ± 0.06 × 10⁹ yr (I = 0.69956 ± 6) and an age of crystallization for KREEP-rich basalt 14310 of [3.94 ± 0.03 × 10⁹yr (I = 0.70041 ± 5). The ages probably date the cooling of shock melts.  相似文献   

Oxygen isotope cosmothermometer revisited     

Naoki Onuma  Robert N. Clayton  Toshiko K. Mayeda 《Geochimica et cosmochimica acta》1974,38(1):189-191

A previously published estimate of the oxygen isotopic composition of the gas of the early solar nebula must be revised in light of the discovery of non-chemical isotope effects in carbonaceous chondrites. The solids which accreted to form the Earth, Moon and ordinary chondrites probably did not equilibrate isotopically with the gas below 1000 K.  相似文献   

Organic versus inorganic trace metal complexes in sulfidic marine waters—some speculative calculations based on available stability constants     

Leonard Robert Gardner 《Geochimica et cosmochimica acta》1974,38(8):1297-1302

A theoretical model has been developed in order to test the hypothesis that simple organic acids are the chief agents of trace metal solubility in H₂S-rich marine waters. The model utilizes stability constant given by Sillen and Martell (1964, 1971) and assumes that the free cation activity of each metal is controlled by simple solubility products. Typical values of pH, pS and Eh are employed in the calculations. The results indicate that free amino acids and hydrocarboxylic acids probably are not effective but that bisulfide and polysulfide complexes may be the chief agents of trace metal solubility. To the extent that it is present, the effect of dissolved organic matter on trace metal solubility probably resides in highly polymerized substances (e.g. humic acids).  相似文献   

Coexisting alkali feldspars in felsic members of the Cauro-Bastelica ring complex,Corsica     

Bernard Bonin  Robert F Martin 《Lithos》1974,7(1):23-28

The granodioritic and gneissic Hercynian basement in Corsica was intruded, in the Triassic, by non-orogenic ring complexes in which the association early rhyolite-hypersolvus granite-granophyre-late subsolvus granite is clearly developed. The association of low albite and maximum microcline in mesoperthites cannot be attributed to Alpine low-grade metamorphism, restricted to fault zones. On a number of lines of evidence, the development of ordered, almost pure K-feldspar in this rapidly cooled complex appears related to an episode of mild reheating attending emplacement of late subsolvus granites, rocks formed from melts enriched, perhaps even saturated in aqueous fluids.  相似文献   

Fluid-pressure variations and fault creep in central California     

Ansel G. Johnson  Robert L. Kovach  Amos Nur 《Tectonophysics》1974,23(3):257-266

Observations of the change of water level in wells near the San Andreas fault in centra California indicate that there are pore-pressure changes associated with the process of fault creep. The sense of water-level and pore-pressure changes may indicate the direction of creep propagation.  相似文献