Fluvial deposits represent the preserved record of one of the major nonmarine environments. They accumulate in large and small intermontane valleys, in the broad valleys of trunk rivers, in the wedges of alluvial fans flanking areas of uplift, in the outwash plains fronting melting glaciers, and in coastal plains. The nature of alluvial assemblages - their lithofacies composition, vertical stratigraphic record, and architecture - reflect an interplay of many processes, from the wandering of individual channels across a floodplain, to the long-term effects of uplift and subsidence. Fluvial deposits are a sensitive indicator of tectonic processes, and also carry subtle signatures of the climate at the time of deposition. They are the hosts for many petroleum and mineral deposits. This book is about all these subjects.

ALTHOUGH the physical geography, mineralogy and natural history of the distant and mountainous parts of Russia have been well illustrated, from the days of Pallas and Hermann to those of Humboldt and Rose, the true geological structure of the country, particularly of her great flat regions, has never yet been adequately developed. We need not now enumerate all those persons who have recently offered contributions towards this object;

Antamina is the largest known copper-zinc skarn (>3000 Mt @ 1.1% Cu and 1.3% Zinc) in the world. It is located in the Northern Andes in Peru, 270 km north of Lima. The deposit formed at approximately 10 Ma by the emplacement of quartz monzonite intrusions into Mid to Late Cretaceous limestones of the Celendin and Jumasha Formations. Mineralisation is hosted as a series of zoned green and brown garnet endoskarns and exoskarns in the form of chalcopyrite, bornite and sphalerite. Elements present within the deposit of significant quantities to affect concentrate value are Cu, Zn, Mo, Ag, Bi and Pb. Antamina produces four concentrates, namely, copper (chalcopyrite and bornite), zinc (sphalerite), molybdenum and lead-silver-bismuth.

El Soldado is the largest (>200 Mt @ 1.4% Cu) of the known Cu manto-type deposits in central Chile. It is strata-bound within a submarine, bimodal calc-alkaline basalt - rhyodacite unit of the Lower Cretaceous Lo Prado Formation., which also contains marine carbonaceous shales and volcaniclastic sandstones. Although stratigraphically restricted, the clustered orebodies are mostly vein-like and discordant, controlled by a system of N-S to NNW faults fonned within a transtensional zone (cymoid loop) of a sinistral, strike-slip brittle shear system. Individual orebodies are zoned, with an external and deeper zone of barren pyrite, followed inward by concentric zones with chalcopyrite-pyrite, chalcopyrite bornite, bornite-chalcocite, and a central zone of chalcocite (± digenite ± covellite) and abundant hematite. The deposit was formed in two main phases: l)a low-temperature, diagenetic phase during which framboidal pyrite developed in association with migrated petroleum, at ca. 130 to 120 Ma; 2) a high-temperature (>300°C from fluid inclusions) hydrothennal phase at ca. 103 Ma, (coinciding with batholith emplacement), that deposited early hematite (± magnetite), followed by chalcopyrite, bornite and chalcocite, mostly replacing pre-existing pyrite, with the excess Fe forming hematite. Gangue minerals are calcite, albite, k-feldspar and chlorite. The hydrothermal Cu mineralization is associated with an increase in Na and depletion in K in host rocks, although there are localised zones of K increase in bornite-chalcocite assemblages near structures. Isotopic studies indicate that: a) the sulphur in diagenetic pyrite provided the bulk of the sulphur for Cu sulphides; b) petroleum was the source of carbon in bitumen and part of the carbonate; c) osmium in diagenetic pyrite was derived from the black shales; d) strontium in calcites was inherited from the Cretaceous arc lavas; e) oxygen isotopes in carbonates, and K-feldspar and atmospheric argon in K-feldspar plus the high salinity of fluid inclusions (21-26% NaCl equivalent) suggest a basinal connate-metamorphic brine was responsible for Cu transport, yet a (distal) magmatic component to the fluids cannot be ruled out.