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GEOLOGY OF THE HORSE MESA DAM QUADRANGLE, MARICOPA AND GILA COUNTIES, ARIZONA v.2.0 The geologic map described in this study covers the Horse Mesa Dam Quadrangle (1:24,000) (Figure 1) (Sheets I-III). The area encompasses part of the northern Superstition Mountains and southern Mazatzal Mountains. Bedrock in this area consists largely of Proterozoic granitic and metamorphic rocks overlain by a thick sequence of early Miocene volcanic rocks. The study in one of a series of related geologic maps from the Arizona Geological Survey that cover the Superstition volcanic field and adjacent areas (Ferguson and Gilbert, 1997; Ferguson and Skotnicki, 1995; Skotnicki and Ferguson, 1995, 1996; Skotnicki and Leighty, 1997; Spencer and Richard, 1995). The rugged physiography of the area is dominated by drainages... Tags: Arizona, geologic map BEDROCK GEOLOGIC MAP OF THE APACHE JUNCTION AND BUCKHORN QUADRANGLES, MARICOPA AND PINAL COUNTIES, ARIZONA v.2.0 This study encompasses the southern part of both the Usery Mountains and the Goldfield Mountains and includes all areas where bedrock is exposed in the Apache Junction and Buckhorn USGS 7.5' topographic quadrangle maps (see figures 1 and 2}. The eastern edge of the study area includes part of the Superstition Mining District and contains many pits and prospects. The region is near the northern margin of the Basin and Range Province and the southern margin of the Transition Zone. Elevations range from about 1280 feet in the northwest comer of the map to 3269 feet near the northeast comer of the map. Field work was carried out between February and April, 1996. Access to the area is good. The Bush Highway, Power Road,... Tags: Arizona, geologic map Geologic Map of the Ninetysix Hills SE, Pinal County, Arizona v.2.0 The Ninetysix Hills of Pinal County, Arizona, consist of a series of low hills and pediment situated about half way between the towns of Florence and Catalina, and are about 70 km ( 45 mi.) north of Tucson (see figure 1). The low spine of hills is underlain by at least four separate granitic plutons. The older pluton, a coarse-grained K-feldspar megacrystic granite exposed in the south, is intruded by a medium-grained granite to granodiorite. Both of these units are locally foliated, but have mineralogic and textural characteristics that suggest they do not belong to the regional suite of 1.65 to 1. 7 Ga-old granites, but are younger. The quartz-porphyritic Teacup granodiorite (Krieger, 1974a, 1974b, Bradfish, 1979)... Tags: Arizona, geologic map Geologic Map of the Ninetysix Hills SW, Pinal County, Arizona v.2.0 The Ninetysix Hills of Pinal County, Arizona, consist of a series of low hills and pediment situated about half way between the towns of Florence and Catalina, and are about 70 km ( 45 mi.) north of Tucson (see figure 1). The low spine of hills is underlain by at least four separate granitic plutons. The older pluton, a coarse-grained K-feldspar megacrystic granite exposed in the south, is intruded by a medium-grained granite to granodiorite. Both of these units are locally foliated, but have mineralogic and textural characteristics that suggest they do not belong to the regional suite of 1.65 to 1. 7 Ga-old granites, but are younger. The quartz-porphyritic Teacup granodiorite (Krieger, 1974a, 1974b, Bradfish, 1979)... Tags: Arizona, geologic map Geologic map of the Goldfield Quadrangle and the northern part of the Superstition Mts. SW quadrangles, Maricopa and Pinal Counties, Arizona v.2.0 The Goldfield Quadrangle and Superstition Mountains are located about 40 km due east ofPhoenix, Arizona, and a few miles east of Apache Junction, and include part of the Superstition Wilderness Area (Figure 1). Aerially extensive exposures of welded tuff form steep, rugged cliffs in the Superstition Mountains and overlie tilted felsic and mafic volcanic rocks, pre-volcanic conglomerate, and Precambrian granite and Pinal Schist. This study was carried out concurrently with mapping in the Florence Junction Quadrangle and the southern part of the Weaver's Needle Quadrangle. Mapping in the Goldfield Quadrangle continued from January through April, 1995. Tags: Arizona, geologic map GEOLOGY OF THE MORMON FLAT DAM QUADRANGLE, MARICOPA COUNTY, ARIZONA v.2.0 The geology of the Mormon Flat Dam Quadrangle is dominated by a thick succession of Miocene volcanic rocks, and by the consequences of two important structural events: 1)formation of the Superstition Cauldron at approximately 18.6 M a (McIntosh, personalcommunication, Ferguson and others, in preparation), and 2) regional extension which wasactive for a short period of time directly before, during, and after eruption of the Apache LeapTuff. The Tertiary stratigraphy consists of three broadly defined sequences: 1) pre-cauldronlavas, 2) syn-cauldron units - chiefly Apache Leap Tuff, and 3) post-cauldron lavas, intrusionsand volcaniclastic sedimentary rocks.Regional extensional tectonism was active over a broad area... Tags: Arizona, geologic map Geologic Map of the Ninetysix Hills NE, Pinal County, Arizona v.2.0 The Ninetysix Hills of Pinal County, Arizona, consist of a series of low hills and pediment situated about half way between the towns of Florence and Catalina, and are about 70 km ( 45 mi.) north of Tucson (see figure 1). The low spine of hills is underlain by at least four separate granitic plutons. The older pluton, a coarse-grained K-feldspar megacrystic granite exposed in the south, is intruded by a medium-grained granite to granodiorite. Both of these units are locally foliated, but have mineralogic and textural characteristics that suggest they do not belong to the regional suite of 1.65 to 1. 7 Ga-old granites, but are younger. The quartz-porphyritic Teacup granodiorite (Krieger, 1974a, 1974b, Bradfish, 1979)... Tags: Arizona, geologic map BEDROCK GEOLOGY OF THE EASTERN AND CENTRAL TANK MOUNTAINS, YUMA COUNTY, ARIZONA v. 2.0 The Tank Mountains lie along the eastern edge of a prominent negative Bouger gravity anomaly (Lysonski and others, 1980) that Grubensky and Bagby (1990) interpreted as evidence for a synvolcanic plutonic complex associated with Miocene silicic calderas of the southern Kofa Mountains, King Valley and northeastern Castle Dome Mountains. The crust which underlies the Miocene volcanic rocks of the Tank Mountains probably consists largely of early Proterozoic plutonic and high-grade metamorphic rocks. This area, along with most of southwestern Arizona was apparently stripped of its Paleozoic and possibly Middle and Upper Proterozoic sedimentary cover during Mesozoic uplift (Spencer and Reynolds, 1989). The study area... Tags: Arizona, geologic map Geology of the Cholla Tank and northern third of the Hoodo Well quadrangles, northern Kofa Mountains, Yuma and La Paz Counties, Arizona v. 2.0 This study encompasses the western-most end of the Little Horn Mountains and the northeast end of the Kofa Mountains. Although relief in the area is less than 2000 feet, with elevations ranging from about 1500 feet in the northeast corner to 3348 feet at New Water (the peak west of Red Rock Pass), both ranges are extremely rugged. The physiography of the area is dominated by high basalt mesas flanked by steep-sided talus slopes. This is a very dry region in which saguaro, palo verde and ocotillo are abundant and seperated by land largely devoid of low brush. Abundant older Quaternary surfaces (Late Pleistocene and older) and talus deposits mantling dark basalt mesas all contain abundant basalt clasts covered with... Tags: Arizona, geologic map Geologic Map of the Picture Mountain Quadrangle, Gila County, Arizona v. 2.0 The Picture Mountain quadrangle is centered on the southwest flank of the Sierra Ancha (see Figure 1). The geology of the area is dominated by the middle Proterozoic Apache Group and the diabase that intrudes it, and some extensive middle Tertiary conglomerates. Elevations range from about 2800 feet in the southwest comer of the map to 6610 feet at Bear Head Mountain. Vegetation. In response to the change in elevation the vegetation changes dramatically across the study area. Saguaro and Palo Verde dominate the lowest elevations in the southwest, with many varieties of cacti. The mid-elevations in the central part of the map contain a mix of open Pinyon-Juniper forest and grassland and thick stands of scrub oak.... Tags: Arizona, geologic map Geologic Map of the Ninetysix Hills NW, Pinal County, Arizona v. 2.0 The Ninetysix Hills of Pinal County, Arizona, consist of a series of low hills and pediment situated about half way between the towns of Florence and Catalina, and are about 70 km ( 45 mi.) north of Tucson (see figure 1). The low spine of hills is underlain by at least four separate granitic plutons. The older pluton, a coarse-grained K-feldspar megacrystic granite exposed in the south, is intruded by a medium-grained granite to granodiorite. Both of these units are locally foliated, but have mineralogic and textural characteristics that suggest they do not belong to the regional suite of 1.65 to 1. 7 Ga-old granites, but are younger. The quartz-porphyritic Teacup granodiorite (Krieger, 1974a, 1974b, Bradfish, 1979)... Tags: Arizona, geologic map