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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 1,279 records · Page 71Linked to original sources
USGS1999

Lithologic, age group, magnetopolarity, and geochemical maps of the Springerville Volcanic Field, east-central Arizona

The Springerville volcanic field is one of the many late Pliocene to Holocene, mostly basaltic, volcanic fields present near the Colorado Plateau margin (fig. 1, in pamphlet). The field overlies the lithospheric transition zone between the Colorado Plateau and the Basin and Range Province (Condit and others, 1989b). Establishing relations in time, space, and composition of the rocks of these plateau-margin fields offers the possibility to integrate more fully into a regional synthesis the detailed geochemistry of these fields now being examined (for example, Perry and others, 1987; Fitton and others, 1988; Menzies and others, 1991). The work also provides baseline information for understanding mantle properties and processes at different depths and locations. Because the Springerville field is the southernmost of the plateau-margin fields, and because it contains both tholeiitic and alkalic rocks (tables 1 and 2, in pamphlet), it is a particularly important location for establishing these patterns in time, space, and composition. Our four thematic maps of the Springerville field were compiled by using digital mapping techniques so that associated petrologic and chemical data could be conveniently included in a geographic information system for one of the plateau-margin fields. Parts of these maps have been included in Condit (1995), a stand-alone Macintosh2 computer program that takes advantage of their digital format.

Arizona↗
USGS1995

Geologic/geomorphologic map of the Chryse Planitia region of Mars

Since the 1970’s, when the Mariner 9 spacecraft revealed the geologic diversity of Mars, the Chryse Planitia region has been noted for its immense outflow channels and chaotic terrain (McCauley and others, 1972; Sharp and Malin , 1975; Baker, 1982, chap. 3; Mars Channel Working Group , 1983). Various proposals for the origin of these features have been offered; most workers have favored a mechanism in which ground water or water-rich debris was expelled from beneath a frozen crust, leading to catastrophic debris flows o r floods that may have contained significant amounts of ice (Baker and Milton, 1974; Carr , 19 79; Nummedal and Prior, 1981; Lucchitta , 1982 ; MacKinnon and Tanaka, 1989). The channels originated on or near the flanks of the volcanotectonic rises of Tharsis (whose east margin is in the west edge of the map region) and Valles Marineris , which suggests that tectonics and igneous activity led to the conditions for discharge. Estimated discharge rates for some channels exceed thos of prehistoric floods on Earth ( Carr , 1979; Komar , 1979; Robinson and Tanaka, 1990) . Some workers think that the discharges may have led to the development of temporary oceans that filled the northern lowlands (Parker and others, 1989; Baker and others, 1991). The Chryse basin ( Chryse and southern Acid alia Planitiae ), which is part of those lowlands, apparently has been the site of lava and sediment deposition (Greeley and others, 1977; Scot and T anaka, 1986).

IMAP↗