نتایج جستجو برای: chemical weathering

تعداد نتایج: 382710  

2007
Jeffrey S. Munroe Gianina Farrugia Peter C. Ryan

We compared the elemental composition of soil and bedrock samples to determine the extent of chemical weathering and the nature of the soil parent material in alpine soils on Vermont's highest summit. Previously it was unclear whether these soils formed through weathering of bedrock, glacial till, or eolian sediment, or solely through the accumulation of organic matter. In eighteen profiles, no...

ژورنال: کواترنری ایران 2018

ecent progresses have been made in the quantification of denudation of eroding landscapes and its links with topography. Despite these advances, data is still sparse in carbonate terrain, which covers a significant part of the Earth’s surface. We can now measure in situ-produced cosmogenic nuclides concentrations in various near-surface materials, allowing accurate quantification of the rates o...

2007
Danny M. Rye Edward W. Bolton

Project Description: Theoretical modeling of coupled fluid flow and chemical reactions, involving kinetics, has been employed to understand the differences between equilibrium, steady-state, and non-steady-state behavior of the chemical evolution of open fluid-rock systems. The numerical codes developed in this project treat multi-component, finite-rate reactions combined with advective and dis...

2007
C. D. Parkinson M.-C. Liang H. Hartman C. J. Hansen G. Tinetti V. Meadows J. L. Kirschvink Y. L. Yung

Aims. The recent Cassini discovery of water vapor plumes ejected from the south pole of the Saturnian satellite, Enceladus, presents a unique window of opportunity for the detection of extant life in our solar system. Methods. With its significant geothermal energy source propelling these plumes >80 km from the surface of the moon and the ensuing large temperature gradient with the surrounding ...

1997
Donald L. Suarez

Simulation models are valuable tools to increase understanding of complex soil chemical processes. Initially modeling was restricted by limited computational power; thus, complex natural systems were often simulated with site-specific, regression-based models. These models (classified as functional models by Hoosbeek & Bryant, 1992) do not deal with the actual processes but were designed to sim...

2001
GEORGE W. A. NYAKAIRU CHRISTIAN KOEBERL HANS KURZWEIL

Kaolin from the Buwambo deposit, located about 27 km north of Kampala (Uganda), has been analyzed for its mineralogical and chemical composition. The kaolin is derived from granite of the basement, which is exposed due to deeply weathered Buganda-Toro cover rocks. Kaolinite is the dominant mineral, with quartz and muscovite/illite as accessory minerals. Chemical data show that the kaolin is com...

2006
J. R. Michalski S. W. Ruff P. R. Christensen E. Cloutis

Introduction and background: Zeolite minerals are hydrated framework aluminosilicates common to altered volcanic and volcanoclastic rocks, and the soils derived from them [1]. The mineralogy, chemistry, textural context, and abundance of zeolites provides insight into chemical weathering, hydrothermal, and metamorphic processes on Earth, in a variety of climates and tectonic settings. Zeolites ...

2004
MARK T. GIBBS GREGG J. S. BLUTH PETER J. FAWCETT LEE R. KUMP

We utilize predictions of runoff from two series of GENESIS (version 1.02) climate model experiments to calculate chemical erosion rates for 12 time slices that span the Mesozoic and Cenozoic. A set of ‘‘control’’ experiments where geography is altered according to published paleogeographic reconstructions and atmospheric pCO2 is held fixed at the present-day value was designed to elucidate cli...

Journal: :Computers & Graphics 2008
Stéphane Mérillou Djamchid Ghazanfarpour

Aging phenomena often play a key role in realistic rendering: excepting when the desired result is specifically a brand-new virtual object, their absence can lead to non-realistic surfaces, looking too clean and smooth. To solve these problems, artists either compose multiple textures manually, or directly modify object geometries. However, such techniques may not be suitable to obtain realisti...

Journal: :Science 2015
J St Clair S Moon W S Holbrook J T Perron C S Riebe S J Martel B Carr C Harman K Singha D deB Richter

Bedrock fracture systems facilitate weathering, allowing fresh mineral surfaces to interact with corrosive waters and biota from Earth's surface, while simultaneously promoting drainage of chemically equilibrated fluids. We show that topographic perturbations to regional stress fields explain bedrock fracture distributions, as revealed by seismic velocity and electrical resistivity surveys from...

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