Mesozoic stratigraphy of the Santa Rita Mountains, southeast of Tucson, Arizona

Abstract

Age and correlation. _____________ _______ Environment of deposition.._____________ 32 6. Modal, chemical, and spectrographic analyses and norms of dacifcic to andesitic rocks of the middle and upper members of the Bathtub Formation _______________________________________________________ 41 7. Chemical and spectrographic analyses and norms of members of the Salero Formation___________________ 72 8. Modal analyses of rhyodacite from the welded-tuff member of the Salero Formation____________________ 72

Climatic and tectonic controls on Jurassic intra-arc basins related to northward drift of North America

“…Volcanic rocks in the western Glance outcrop belt were erupted by a wide variety of mechanisms, including silicic plinian and phreatoplinian fall, andesitic vulcanian explosions, rhyolitic to dacitic lava dome extrusion and collapse into hot block-and-ash fl ows, dacitic to andesitic fl ow brecciation, and effusion of coherent (nonbrecciated) basaltic andesite lava fl ows (Fig. 2;Hayes and Raup, 1968;Hayes, 1970;Drewes, 1971c;Kluth, 1982;Krebs and Ruiz, 1987;Lipman and Hagstrum, 1992;Bassett and Busby, 1996 and this volume;Busby and Bassett, 2005). This wide range in compositions and eruptive behaviors does not support the interpretation of Lawton and McMillan (1999) that volcanic rocks interstratifi ed with Glance Conglomerate are bimodal in composition and restricted to caldera-forming silicic eruptions associated with basalt lava fl ows, in a manner typical of continental rift settings.…”

“…The reported compositions of these volcanic rocks is based largely on phenocryst mineralogy (Hayes and Raup, 1968;Hayes, 1970;Drewes, 1971c;Kluth, 1982;Lipman and Hagstrum, 1992). Geochemical analyses on volcanic rock samples from the Canelo Hills region (Fig.…”

Relationship of faults in basin sediments to the gravity and magnetic expression of their underlying fault systems

“…Magmatic activity began again in the Late Oligocene with the deposition of the Grosvenor Hill volcanics, primarily rhyolitic in composition, and extruded as flows and tuffs. Feeder dikes and laccoliths commonly intruded the Grosvenor volcanics (Drewes, 1971b).…”

“…Drewes (1971a) sediments. This is sensible given that the Nogales is a high-density unit that has been described as well indurated (Drewes, 1971b). …”

Structural control of geochemical anomalies in the Greaterville mining district, southeast of Tucson, Arizona

“…The klippe of Willow Canyon Formation northwest of Enzenberg Canyon is also truncated by the northwest-trending major fault, and another sliver of that formation lies along the fault at the crest of the Santa Rita Mountains beyond the edge of the mapped area. Several other high-angle faults, both normal faults with graben blocks of Bisbee and tear faults merging with thrust faults, trend northwestward across the northern Santa Rita Mountains (Drewes, 1966 and1968a;Drewes and Finnell, 1968).…”