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Showing 451 to 459 of 459 (0.038 seconds)Spelling suggestions: "subject:"eology -- arizona"" "subject:"eology -- orizona""
| 451 |
A determination of the sulfur isotopic signature of an ore-forming fluid from the Sierrita porphyry copper deposit Pima County, ArizonaTurner, Kent January 1983 (has links)
No description available.
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| 452 |
Metamorphic effects of the Leatherwood Quartz Diorite, Santa Catalina Mountains, Pima County, ArizonaWood, Michael Manning, 1937- January 1963 (has links)
No description available.
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| 453 |
Geologic history of an ash-flow sequence and its source area in the Basin and Range province of southeastern ArizonaMarjaniemi, Darwin Keith, 1940-, Marjaniemi, Darwin Keith, 1940- January 1970 (has links)
The tertiary history of the Chiricahua volcanic field of southeastern Arizona is essentially that of rhyolitic ash-flow deposition and concomitant block faulting in the period from 29 to 25 m.y., as determined by K-Ar analysis. The Rhyolite Canyon ash-flow sheet is the youngest of three sheets, each more than 1000 feet thick. Its distribution is limited mainly to the Chiricahua and northern Pedregosa Mountains with a lesser amount of deposits in the neighboring Swisshelm and Peloncillo Mountains. It is estimated that the original areal extent was of the order of 700 square miles and that the volume of deposits was around 100 cubic miles. The source area of the Rhyolite Canyon sheet is identified as a 13-mile diameter caldera, named the Turkey Creek caldera. This is the first major caldera of the Valles type described in the Mexican Highland and Sonoran Desert sections of the Basin and Range. It is unique because of its denudation. Erosion to 5000-foot depth locally has exposed thick sections of moat deposits and a fine grained monzonite pluton associated with central doming. Rhyolite Canyon tuff in the caldera, some 3000 feet thick, is domed and intruded by the monzonite. More than 1500 feet of tuff breccia, tuffaceous sediments, and rhyolite flows are exposed in the moat, along with 3000 feet of monzonite forming annular segments a couple miles wide abutting or overlying rocks forming the caldera wall. The most monzonite is similar to that in the dome and was emplaced amidst the period of deposition in the caldera. Petrographic and trace element analyses indicate a cogenetic relation between the Rhyolite Canyon sequence and the moat rhyolites. The K-Ar age of the Rhyolite Canyon tuff is very close to that of the monzonite. The ash-flow sheet immediately underlying the Rhyolite Canyon sheet is also very close in age as indicated by K-Ar analyses. Block faulting and tilting took place between the two sheets and also following the deposition of the Rhyolite Canyon sheet. There is evidence that the present basin-range structure was not established until after the Rhyolite Canyon sheet had been emplaced.
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| 454 |
Environmental geology of ski area developmentsKypfer, Marvin Douglas, Kypfer, Marvin Douglas January 1979 (has links)
No description available.
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| 455 |
Stratigraphy and Sedimentology of the Bisbee Group in the Whetstone Mountains, Pima and Cochise Counties, Southeastern ArizonaArchibald, Lawrence Eben January 1982 (has links)
The Aptian-Santonian(?) Bisbee Group in the Whetstone Mountains comprises 2375 m of clastic sedimentary rocks and limestones. The basal Glance Conglomerate unconformably overlies the Pennsylvanian-Permian Naco Group. It consists of limestone conglomerates which were deposited in proximal alluvial fan environments. The superadjacent Willow Canyon Formation contains finer grained rocks which were deposited in the distal portions of alluvial fans. The lacustrine limestones in the Apache Canyon Formation interfinger with and overlie these alluvial fan facies. The overlying Shellenberger Canyon Formation is composed mostly of terrigenous rocks derived from westerly terranes. This formation contains thick sequences of fluvio-deltaic facies as well as a thin interval of estuarine deposits which mark a northwestern extension of the marine transgression in the Bisbee -Chihuahua Embayment. The youngest formation (Upper Cretaceous?) in the Bisbee Group, the Turney Ranch Formation, consists of interbedded sandstones and marls which were deposited by fluvial and marine(?) processes.
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| 456 |
The Chinle Formation of the Paria Plateau Area, Arizona and UtahAkers, J.P. January 1960 (has links)
In the Paria Plateau area of northern Arizona and southern Utah the Chinle formation of Upper Triassic age consists of a thick series of Ienticular sandstone, siltstone, claystone, and limestone. The series thins northwestward from about 900 feet at Lees Ferry, Ariz., to about 800 feet at Paria, Utah. Four members of the Chinle formation are recognized—1) the basal Shinarump member composed of conglomeratic sandstone and subordinate shale, 2) a unit, herein named the Lowery Spring member, composed of sandstone and mudstone, 3) the Petrified Forest member composed of bentonitic siltstone and claystone and thin sandstone, and 4) the Owl Rock member composed of cherty limestone and calcareous siltstone. Only the Petrified Forest member is present at all localities in the Paria Plateau area. The Shinarump member was deposited in topographic low areas on an erosion surface and its distribution is irregular. The Lowery Spring and Owl Rock members grade and pinch-out toward the northwest and are not present at Paria, Utah. The upper contact of the Chinle formation is locally unconformable. The three lowermost members were deposited on a broad, flat plain between the Cordilleran geosyncline and highlands to the southeast. In Owl Rock time the rising Cordilleran geanticline cut off the north-westward drainage of Chinle streams and a depositional basin trending southwest was formed.
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| 457 |
Structural Investigations of the Italian Trap Allochthon, Redington Pass, Pima County, ArizonaBenson, Gregory Scott January 1981 (has links)
Italian Trap Allochthon is a rare upper-plate exposure of Paleozoic metasedimentary and Precambrian to Tertiary crystalline tectonites in the Santa Catalina-Rincon metamorphic core complex. Elsewhere in the complex, metasedimentary tectonite is usually restricted to an autochthononous position. The internal structures of the allochthon consist of numerous low-angle faults, tear faults, and overturned asymmetric and upright folds. Close association of the low-angle faults and asymmetric folds, and vergence of the folds, indicates that these folds were formed during westward transport along the low-angle faults. The structures of the allochthon are truncated and rotated to the northeast by a listric (?) normal fault. The probable shape of the fault surface, together with the northeastward rotation of the internal structures, suggests translation of the allochthon from the northeast to the southwest. The fact that metasedimentary tectonites are found in upper- plate position indicates that the listric (?) normal faulting post-dates the metamorphism of the Paleozoic and Mesozoic strata. Metamorphism in turn was part of the development of the Santa Catalina-Rincon metamorphic core complex. It is inferred that the Italian Trap Allochthon was emplaced in the final stages of profound regional extension which prevailed during the mid-Tertiary in southern Arizona.
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| 458 |
Precambrian Geology of the Cottonwood Cliffs Area, Mohave County, ArizonaBeard, Linda Sue January 1985 (has links)
A belt of Early Proterozoic rocks crops out in the Cottonwood Cliffs area, northwest Arizona. The belt contains an eastern and a western assemblage separated by the Slate Mountain fault. The western assemblage consists of mafic to felsic metavolcanic rocks, metapelites, and metaconglomerates. The eastern assemblage consists of phyllites, felsic to intermediate metavolcanic rocks, metagraywackes, and metagabbro bodies. The belt is bounded to the east by foliated granodiorite. The Valentine granite intruded the belt on the west and north. Steeply-plunging lineations and fold axes, and northeast-trending vertical foliation dominate the structural fabric. The regional elongation direction is near-vertical, as indicated by mineral and pebble lineations, and is parallel to fold axes. Although only one deformational event is evident, the intensity of that event may have obliterated evidence of any earlier deformation. Tertiary basalts and the Peach Springs Tuff locally overly the metamorphic rocks. Cenozoic normal faults in the area are mostly of minor displacement.
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| 459 |
Geology of the Palo Verde Ranch Area, Owl Head Mining District, Pinal County, ArizonaApplebaum, Steven January 1975 (has links)
A quartz diorite intrusion of probable early Tertiary age that crops out over at least 6 square miles in the Palo Verde Ranch area in Pinal County, Arizona was mapped as a distinct intrusion. The quartz diorite intrudes an area comprising Pinal Schist, Oracle granite, andesitic flows, granoaplite, and dike rocks including both pegmatite and diabase. Two major physical features, the Owl Head Buttes and Chief Buttes volcanic areas, both remnants of an extensive early Tertiary series of flows of intermediate composition that covered the area, now remain as lava-capped buttes above the pediment. Weak but persistent fracture-controlled copper mineralization is found in the quartz diorite and the Pinal Schist at or near their mutual contacts in the form of chrysocolla, malachite, black copper oxides, chalcocite, chalcopyrite, and bornite, in decreasing order. Pyrite is rare. Alteration related to northeast and northwest-trending fractures increases in intensity from the common propylitic to argillic to the northeast toward the San Juan claims area. A barely discernible increase in copper sulfides mirrors the alteration zoning, although geochemical sampling showed background copper in the quartz diorite to be more uniform away from fractures.
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