All aspects of the Earth’s history and structure, including its majestic mountains, giant rift valleys, and deep ocean basins, were fashioned by mobile crustal plates.The Earth’s outer shell is made up of a dozen or o plates composed of the upper mantle, or lithosphere, and the overlying continental and oceanic crust.The plates ride on the semimolten rocks of the upper mantle and carry the continents along with them.The movement of the plates accounts for all geologic activity taking place on the planet’s surface. In this manner, plate tectonics is continously changing and rearranging the face of the Earth.

The debate regarding whether or not melting anomalies are fuelled by hot diapirs from the deep mantle – the Plume hypothesis – or whether they arise from shallow processes ltimately related to plate tectonics – the Plate hypothesis  – is an extraordinarily rich cross - disciplinary subject with seemingly endless ramifi cations. Relevant material is scattered far and wide, and because of this, over the last decade, scientists have come together and tried to address this problem using the website www.mantleplumes.org.

Platinum-group elements (PGE) and gold were analyzed by ICP-MS after the Ni-sulphide fire assay pre-concentration step in 44 rocks from 5 orogenic mafic-ultramafic massifs of the central and southern Urals. They comprise: (a) ring-zoned, Ural-Alaskan type bodies of the 'Pt-bearing belt' (Kachkanar, Tagil, Uktus); and (b) lherzolite-harzburgite complexes overlain by layered wehrlite, gabbro, and diorite (Nurali, Mindyak) supposed to be ophiolite-type suites.

Teresa Valente Editorial for Special Issue “Pollutants in Acid Mine Drainage” Reprinted from

Darrell Kirk Nordstrom Geochemical Modeling of Iron and Aluminum Precipitation during Mixing and Neutralization of Acid Mine Drainage
Cl ´ementine Drapeau, Rabei Argane, C ´ecile Delolme, Denise Blanc, Mostafa Benzaazoua and Rachid Hakkou et al. Lead Mobilization and Speciation in Mining Waste: Experiments and Modeling
Elliott K. Skierszkan, John W. Dockrey, K. Ulrich Mayer, Viorica F. Bondici, Joyce M. McBeth and Roger D. Beckie Geochemical Controls on Uranium Release from Neutral-pH Rock Drainage Produced by Weathering of Granite, Gneiss, and Schist
Mariana Lemos, Teresa Valente, Paula Marinho Reis, Rita Fonseca, Itamar Delbem and Juliana Ventura et al. Mineralogical and Geochemical Characterization of Gold Mining Tailings and Their Potential to Generate Acid Mine Drainage (Minas Gerais, Brazil)