نتایج جستجو برای: siliceous composition

تعداد نتایج: 260770  

2000
S. B. TAYLOR

Quantitative analysis of siliceous microfossils in 210Pb-dated Lake Michigan sediments shows five time zones in microfossil abundance and composition. Sediments deposited before 1885 contain low abundances comprising species associated with very oligotrophic lakes. Between 1885 and 1925 abundance increases slowly as does the ratio of planktonic diatoms to benthic diatoms and chrysophyte remains...

رهگشای, محمد , شفائی مقدم , هادی , منصف, ایمان ,

In Khoy ophiolitic massif (NW of Iran) three types of quartzite and also quartz bearing veins can be distinguished: massive quartzite, quartz bearing veins in the amphibolites and siliceous veins in the radiolarian cherts. Massive quartzites contain quartz porphyroclasts associated with very   small- deformed quartz neoblasts. These quartzites are deformed in regime I and recrystallized as grai...

Atashy, H. , Fallahnejad, M. , Rahnama-Rad, J. ,

Inhibiting of gel forming, under certain pH and temperature conditions, is one of the most effective ways in leaching process of siliceous zinc concentrates. In order to provide the crucial conditions for extracting zinc from siliceous zinc concentrates, the variables, e.g. temperature, pH, time duration, rotation speed of mixer and the remaining time which are known to affect the leaching proc...

2003
Fabio Florindo Andrew P. Roberts Martin R. Palmer

[1] Magnetite dissolution, and consequent loss of magnetization, is widely observed in reducing sedimentary environments, where the decrease in Eh-pH values with depth is driven by bacterially mediated degradation of organic carbon. We have observed low magnetizations in sediments with elevated pore water silica concentrations that arise from diagenesis of biogenic silica and/or silicic volcani...

Journal: :Geochemistry, Geophysics, Geosystems 2003

2018
Maria Tudela-Isanta Eduardo Fernández-Pascual Malaka Wijayasinghe Simone Orsenigo Graziano Rossi Hugh W Pritchard Andrea Mondoni

Understanding the key aspects of plant regeneration from seeds is crucial in assessing species assembly to their habitats. However, the regenerative traits of seed dormancy and germination are underrepresented in this context. In the alpine zone, the large species and microhabitat diversity provide an ideal context to assess habitat-related regenerative strategies. To this end, seeds of 53 spec...

Journal: :Zootaxa 2015
Magdalena Łukowiak

An abundant and diversified assemblage of siliceous loose sponge spicules has been identified in the Late Eocene deposits cropping out along the southern coasts of Australia. Based on the comparison of the obtained spicules with those of living sponges, representatives of at least 43 species within 33 genera, 26 families, and 9 orders of "soft" Demospongiae and Homoscleromorpha have been identi...

2006
T. Roussel C. Bichara

In this work, we present a Grand Canonical Monte-Carlo simulation results for the adsorption of carbon vapour in the pores of faujasite zeolite (in its siliceous form). The carboncarbon interactions are described within the frame of a Tight Binding approach (fourth momentum’s method) while the carbon-zeolite interactions are modelled using a PN-TrAZ physisorption potential. Siliceous faujasite ...

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