مواد و معدنی تشکیل شده توسط هوازدگی

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Weathering, transportation, Comentation ‘and compaction itwsineation) pain, weathating, wansportation, ‘ane deposition upiit, ‏و مد‎ ‏همه‎ ‎‘and ‎deposition solaitcation ‏ا‎ Metamorphic Rock Copyright © 2005 Pearson Prentice Hall, Inc. 

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Gedkwedary Provesses 0) Ordborieg S wows Weathering and Land transport and deposition by water, wind, ice ©) Tracspont & 9( ‏موس‎ 

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aed dstoteqrutiva oF rool Ground surface Produ oF weuhertay 24 ‏ید مه ابر‎ ج لا امه سس لاب ‎c is poled‏ Qovewed oP sedkvedt te ‏سور لهج‎ 

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Oe mh marred hd Qevkoard Orukertay - Osta yruiod oP rock wihou choage to chewicd ‏بي تدا‎ SO Ka a aad Qevowposiion vp rock us the result bP Pa eas 

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۱0 Processes BT a Tela A a nal eR ‏و‎ SO ce ‏و‎ rewtor wit oer (rock net) ne Mee dace aa ae ca ad 

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Pyroxene FeSiO) Iron pyroxene dissolves to release silica and ferrous iron to solution G2 so, Vis Ferrous iron is oxidized by oxygen molecules 0 to form ferric iron Feit 1 Ferric iron combines ‏9و‎ with water to precipitate a solid, iron oxide, from solution 

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‎uctd which‏ یخی و( عون ی اه لجت و (ه م0 ‎widPes suPuce wor und rod‏ ‎Pyrite + mayen + weer = sPa wld + weber (evo suPide) (04 oxide) ‎ 

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Hydrolysis Feldspar + carbonic acid +۳0 = kaolinite (clay) + dissolved K (potassium) ion + dissolved bicarbonate ion + dissolved silica Clay is a soft, platy mineral, so the rock disintegrates A.smll proportion of carbonic cd movecules ionites to form hydrogen ions (H*) and bicarborate ions (HO) making the water cropess sightly adide The sighdy aide water dissolves potssium ions and sic from feldspar, مره transforming trea lait: drogen ions ae reaied inthe water of heey Dissolved sia, potssium ions (K*), ard bcarbonate ions (HCO;) run of into Fivers and so 

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۱۱۰۱-۱721۱ Products of Weathering Mineral Residual Products Material in Solution Quartz Quartz grains Silica Feldspars Clay minerals Silica K*, Na*, Ca2* Amphibole Clay minerals Silica (hornblende) Limonite Ca**, Mg?* Hematite Olivine Limonite Silica Hematite 9 Copyright © 2005 Pearson Prentice Hall, Inc. Clay minerals further decompose to aluminum hydroxides (bauxite) and dissolved silica. 

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Controls on rates of weathering * Relative oa Siete Mrs see, resistance Han ence 3-5 5 of primary cai ‏سس‎ ‎minerals to chemical 2 weathering اه مس ‎sen‏ ‏۳3 Copyright© 2005 Pearson Pence Hal, nc * Climate - especially: 1. availability of water (for chemical weathering), 2. temperature (increases reaction rates), and 3. vegetation (which increases the availability of carbonic acid) 

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© horizon Loose and Partly decayed organic matter —1- A horizon mixed with Some humus: E horizon Light colored mineral particles. Zone of eluviation and leaching B horizon Accumulation of glay transported S horizon Partially altered parent material Unweathered Parent material Copyright © 2005 Pearson Prentice Hall, Inc. ۱ Mineral matter افو Subsoil Solum or “tue soil” 

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Soil classification 1) Laterite or oxisol Forms in a hot, humid climate. Soil is deep red, hard and infertile. Plants recycle nutrients ina thin A and 0 horizon. Wet climate Thin or absent humus Thick masses of insoluble iron and aluminum oxides; occasional quartz Iron-rich clays and aluminum hydroxides Thin leached zone Mafic igneous bedrock 

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Copyright © 2008 Pearson Prentice Hall, Inc OePorestatioa recover the Pere organic kver. Phe vader vic ‏,لحكلا جا امد‎ ‏انا نا‎ hardaess wheat dries out, cod i dPPial io cubivote, hrc (Prow bound) oad inva (Proc ieoocite) cos be spiced row these svi. 

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Temperate climate Humus and leached soil A (quartz and lay minerals present) aluminum oxides B precipitated: all soluble materials. such as carbonates, leached away } Some iron and Granite © bedrock 

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Gol wep oP ‏لاوس‎ Global Soil Regions 

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۱0۸ Porwed by weakertay: (tne) 

Minerals formed by weathering Sedimentary Processes 1) Weathering & erosion 2) Transport & 3) deposition 4) Lithification Weathering: decomposition and disintegration of rock Product of weathering is regolith or soil Regolith or soil that is transported is called sediment Movement of sediment is called erosion Weathering Processes • Mechanical Weathering Disintegration of rock without change in chemical composition • Chemical WeatheringDecomposition of rock as the result of chemical attack. Chemical composition changes. Mechanical Weathering •Frost wedging •Alternate heating and cooling •Decompression causes jointing Chemical Weathering Processes • Hydrolysis - reaction with water (new minerals form) • Oxidation - reaction with oxygen (rock rusts) • Dissolution - rock is completely dissolved Most chemical weathering processes are promoted by carbonic acid: H2O +CO2 = H2CO3 (carbonic acid) Oxidation Oxidation can affect any iron bearing mineral, for example, ferromagnesian silicates which react to form hematite and limonite Oxidation of pyrite and other sulfide minerals forms sulfuric acid which acidifies surface water and rain Pyrite + oxygen + water = sulfuric acid + goethite (iron sulfide) (iron oxide) Hydrolysis Feldspar + carbonic acid +H2O = kaolinite (clay) + dissolved K (potassium) ion + dissolved bicarbonate ion + dissolved silica Clay is a soft, platy mineral, so the rock disintegrates Products of weathering Clay minerals further decompose to aluminum hydroxides (bauxite) and dissolved silica. Controls on rates of weathering • Relative resistance of primary minerals to chemical weathering • Climate – especially: 1. availability of water (for chemical weathering), 2. temperature (increases reaction rates), and 3. vegetation (which increases the availability of carbonic acid) A soil profile develops slowly over time Soil classification 1) Laterite or oxisol Forms in a hot, humid climate. Soil is deep red, hard and infertile. Plants recycle nutrients in a thin A and O horizon. Deforestation removes the fertile organic layer. The underlying soil is infertile, dries to brick-like hardness when it dries out, and is difficult to cultivate. Aluminum (from bauxite) and iron (from limonite) can be mined from these soils. Soil classification 2) Alfisols and mollisols: Form in warm or cool, temperate climates. Soil is grey and clay-rich, fertile. Alfisols are forest soils, mollisols form in grasslands Soil map of world Greens – Alfisols & mollisols Red – Oxisols Tan - Aridosols Minerals formed by weathering: (pages 191-192) Clay minerals: kaolinite, smectite (Na, Ca), illite (K) (pages 255-256) Aluminum oxides and hydroxides: gibbsite, diaspore, boehmite (consituents of bauxite) (pages 371-374) Iron oxides and hydroxides: hematite, goethite, lepidocrosite, limonite Mn oxides and hydroxides (bog ores or wad): pyrolusite, romanechite, manganite, others