The Roberts Mountains of north-central Nevada are comprised of Paleozoic sedimentary rocks that host several gold deposits and subeconomic gold resources (Fig. 1). These gold occurrences are within a regional alignment of precious and base metal deposits in north-central Nevada termed the Battle Mountain-Eureka mineral belt (Roberts, 1966). Field relations and radiometric ages in three areas of the Roberts Mountains (Maher et al., 1990) allow assignment of minimum and probable maximum ages for gold mineralization. New radiometric age data from the Roberts Mountains and other precious and base metal deposits within the Battle Mountain-Eureka mineral belt are combined in this report with previously published geologic data to construct a metallo-genic framework for gold and other metallic deposits in north-central Nevada.

Since V.M. Goldschmidt's (1911) classic study on the Oslo area of Norway, contact aureoles have provided excellent natural "laboratories" for the elucidation of the processes and conditions of metamorphism. Reverdatto (1973) compiled petrologic studies on contact metamorphism. However, considerable research on the processes and controls of contact metamorphism has been carried out in the last two decades. This volume presents a review of contact metamorphism from a variety of geological subdisciplines (igneous and metamorphic petrology, geochemistry, thermal modeling, and structural geology). This chapter presents a brief overview of the controls and processes of contact metamorphism, and is primarily intended for readers who are relatively unfamiliar with this topic <...>

The zone between land surface and the water table, which forms the upper boundary of  the groundwater region, is known as the vadose zone. This zone is mostly unsaturated—or more precisely, partially saturated—but it may contain a saturated fraction in the vicinity of the water table due to fluctuations in water levels or capillary rise above the water table.

Tectonostratigraphic terrane analysis of the western and central Baltic Shield defines a framework for continental growth through the period 2.50-1,75 Ga, Eight discrete terrenes can he defined in this part of the Svecokarelian orogen: the older cratonic Kuhmo and HsaJmi terranes, the hybrid Lapland and Savo province allochthonous ler-ranes, the juvenile island-arc-I ike Skeltefte-Savonlinna and south Finland-central Sweden terranes. (he back-arc or arc-tike Outokumpu nappe, and the ophiolitic (oceanic?) Jormua nappe. Stitching events can also he recngnized. These include the ca- 1.88-1.87 Ca Svionian magmalic arc, the ca. 2.44 Ca Koillismaa intrusions, the Kalevian flysch basin, and the Bolhnian basin. Constraining the age of these stitching events permits the construction of an accretion history in which the "Svecok3relian orogeny" can be resolved as a number of accretion events, deformation episodes related to accretion or mjgmato-tectonic episodes. These events, defined here, include the pre-2.44 Ca Pohjolan accretion of the component parts of the Lapland hybrid terrane. the ca. 1.95 Ca Kyllikian accretion of the Karelian collage, Ihc ca. 1.90 Ga Karelian orogeny marked by the development of the Savo thrust bell in response to the accretion of the Skellefte-Savonlinna terrane to the Karelian collage, and (he ca. 1.88-1.87 Ga Svionian magmalic arc. The whole Svecokaretian collage had assembled by ca. 1.85 Ca, an amalgamation succeeded and stitched by a diverse collection of igneous and thermal events through the period 1.85-1.75 Ca.