| Summary: | Frequent tephra deposition and a steady influx of aeolian material of diverse origin dominate soil formation in Iceland. Little is known about the weathering behaviour, mineral formation and alteration of tephra and Icelandic soils after tephra deposition. This thesis presents the results from extensive studies on soil mineralogy and pedogenesis in various Icelandic soil types and different soil environments. The sampling sites were selected according to the presence of the light coloured rhyolitic tephra from the Öræfajökull eruption in 1362 CE and a dark-coloured basaltic Veiðivötn tephra from 1477 CE in the volcanically active area south of Vatnajökull, SE Iceland. All investigated soils were acidic and dominated by sand. Indicated by Feo/Fed ratios above 0.75, they classify as being in an early stage of chemical weathering and soil development. The major portion of the clay size particles are mainly derived from amorphous and poorly crystalline constituents (allophane and ferrihydrite). However, traces of layer silicates (smectite, hydroxy interlayerd minerals and secondary chlorite) were found at all sites. The determining factor of pedogenesis in the histosols was the OM, but the aeolian transport of tephra over long distances and re-deposition as well as local site conditions, rather than the primary composition of the parent material, were the important factors in the development of all investigated soils and the alteration of minerals. Icelandic soils develop in a very dynamic environment. None of the profiles represented a well-developed-pedon, but appeared disturbed over time, showing signs of external influences. Tíð eldgos með tilheyrandi gjóskufalli og stöðugt áfok vindborinna efna af ólíkum uppruna setja mestan svip á jarðvegsþróun á Íslandi. Skortur er á þekkingu á veðrun, myndun og ummyndun steinda í gjósku í íslenskum jarðvegi í kjölfar gjóskjufalls. Í þessari ritgerð eru niðurstöður umfangsmikillar rannsóknar kynntar, sem tekur til steindafræði og jarðvegsþróunar í mismunandi jarðvegsflokkum ...
|
|---|