The mineralogy and morphology of a soil with a cambic horizon (Stingal) and a soil with an argillic horizon (Hansel), occurring in northern Utah, were studied. Pedons representing the central concept of each of the soils were sampled by genetic horizon for laboratory analyses. Particle- size distribution, calcium carbonate equivalent, cation-exchange capacity, organic carbon , and the mineralogy of the silt, coarse clay, and fine clay fractions were determined. Thin sections of the soils were examined with a petrographic microscope. Selected peds were observed using a scanning electron microscope, and elemental analyses were made with an x-ray analyzer. The two soils were found to be similar in many respects . The particle-size distribution and mineralogy were essentially the same, indicating the similarities of parent materials and the nature of pedogenic processes. As expected, the argillic horizon contained more. fine and total clay than did the cambic horizon, and the Hansel soil showed signs of more intense weathering. Both factors are related to the greater age of the Hansel soils. The clay increase in both the cambic and the argillic horizons was attributed to a combination of ill situ clay formation and illuviation. This conclusion was based on the lack of depositional discontinuities, greater ratios of fine to total clay in the B horizons, and the electron microscopic observation of discontinuous clay films in pores of the Hansel soil. The lack of visible clay films in thin section is probably the result of soil mixing by cicada and/or the prevention of translocation by carbonates. The scanning electron microscope proved to be useful in the investigation of the two soils. The similarities of the two soils were apparent from laboratory analyses and scanning microscope observations. Evidence of illuviation, which was lacking in thin section, was visible with the scanning electron microscope, thus demonstrating the potential of the microscope in classifying and interpreting soils in future investigations.

The Copiapó region in northern Chile contains numerous intrusion- and volcanichosted IOCG vein systems. These veins share many features with larger IOCG systems in the region (e.g., Candelaria, Punta del Cobre), including abundant hydrothermal magnetite or hematite ± Cu, Au, REE, and other elements, and exhibit similar styles of mineralization including voluminous breccias, stockwork, and massive veins. The relatively simple geometries and small size of veins offer advantages for study of zoning and genesis in an IOCG system; and, they also provide an interesting counterpoint to classic epithermal Ag-Au veins. The vein systems exhibit systematic patterns in the alteration and mineralization zoning in both time and space. Deeper exposures are characterized by high-temperature styles of sodic and sodic(-calcic) alteration with Fe and Cu depleted vein fill assemblages. This passes upwards through a proximal zone of magnetite-dominated vein fill with sparse to absent copper, and into a magnetite-dominated, copper-bearing portion of the vein. Copper is best developed at intermediate to shallow levels in association with the hematite-dominated portions of the system. More distal, carbonate dominated facies with minor hematite and chalcopyrite are also present. Shallow levels of the vein system may be characterized by a low-sulfur style of advanced argillic alteration, that may be stratabound, in discordant breccia bodies, or structurally controlled on faults. The assemblages differ from other ore forming environments by their lack of sulfide and/or sulfate minerals, and the abundance of hypogene iron oxide phases (hematite and/or magnetite). Vein systems are dominated by brecciation events that record repeated, cyclic pulses of mineralizing fluids. Stable and radiogenic isotopic analyses, combined with fluid inclusion and mineral phase equilibria indicate the fluids were hypersaline brines (generally >40 wt% NaCl(eq)) over a temperature range of 200º-450ºC. The shallow formation, structural styles, repeated mineralization events, and size of the IOCG vein systems have many parallels to the classic precious-metal rich Ag-Au epithermal systems. Nonetheless, the two types of veins differ in their geochemistry, reflecting the large differences in fluid salinities, commonly <10 wt% NaCl(eq) in epithermal settings as compared to 15 to > 50 wt% NaCl(eq) in IOCG systems.