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The middle Miocene from 17 to 14 Ma was a time of elevated mammalian diversity in western North America that coincided with the regional development of topographic complexity and the last global warming interval of the Neogene. Understanding the evolutionary and ecological processes that govern past diversity trends and contribute to modern diversity gradients in relation to landscape and climate requires the integration of faunal and paleoenvironmental datasets across spatio-temporal scales. Using a variety of approaches, I analyzed small-mammal and environmental data to investigate diversity and dietary-ecology responses to changes in climate across space today and through time during the middle Miocene. I additionally utilized fossil-record simulations to assess the influence of variable preservation history on estimates of diversification rates in relation to landscape change. This thesis sheds light on how interactions between tectonic activity and climate warming influenced species richness and ecology from local to regional scales.

The middle Miocene from 17 to 14 Ma was a time of elevated mammalian diversity in western North America that coincided with the regional development of topographic complexity and the last global warming interval of the Neogene. Understanding the evolutionary and ecological processes that govern past diversity trends and contribute to modern diversity gradients in relation to landscape and climate requires the integration of faunal and paleoenvironmental datasets across spatio-temporal scales. Using a variety of approaches, I analyzed small-mammal and environmental data to investigate diversity and dietary-ecology responses to changes in climate across space today and through time during the middle Miocene. I additionally utilized fossil-record simulations to assess the influence of variable preservation history on estimates of diversification rates in relation to landscape change. This thesis sheds light on how interactions between tectonic activity and climate warming influenced species richness and ecology from local to regional scales.

Aquifers in the arid alluvial basins of the southwestern U.S. are recharged predominantly by infiltration from streams within the basins and by water entering along the margins of the basins from surrounding mountains (mountain -front recharge). The Tucson Basin of Southeastern Arizona is such a basin. The Santa Catalina Mountains form the northern boundary of this basin and receive more than twice as much precipitation (about 70 cm/yr) as the basin does (about 30 cm/yr). In this study environmental isotopes were employed to investigate the migration of precipitation basinward through joints and fractures. Water samples were obtained from springs in the Santa Catalina Mountains. Stable isotopes and thermonuclear bomb-produced tritium enabled qualitative characterizations of flow paths and flow velocities. Stable isotopic measurements fail to display a direct altitude effect. Tritium values indicate that although a few springs discharge pre-bomb water, most springs discharge waters from the 1960's or later.

Attenuation of regional seismic phases in the Great Basin; Regional seismic recordings of the Soviet nuclear explosion of the joint verification experiment; Observations of high-frequency P wave earthquake and explosion spectra compared with omega to the minus 3 power, omega to the minus 2 power, and Sharpe source models; and Crustal structure in eastern Kazakh, USSR, from teleseismic receiver functions.

Work was completed on yield determination at the Soviet test site on Novaya Zemlya. Magnitudes and yields, determined for 30 explosions using Lg amplitudes recorded in northwestern Europe, ranged between 2.5 and 4900 kt, the largest since April 1976 being about 145 kt. Studies were completed on seismic wave attenuation of surface waves at intermediate periods and of Lg waves at 1 Hz in several regions of the world. Limits were determined for the degree of frequency dependence of Q sub beta which can occur in the crust in stable and tectonically active regions. A stochastic convolution model was proposed for Lg coda at distances > 200 km which considers the effects of dispersion scattering and mode conversions at those distances. A back projection tomographic method was developed to regionalize large-scale lateral variations of coda Q for Lg waves which traverse long continental paths. A seismically active region in the New Madrid seismic zone was found to be characterized by lower than normal Q values. In the western United States we find that Q values in the upper mantle vary laterally, becoming smaller from east to west. Crust of the Basin and Range province has a low-Q upper crust overlying a lower crust with higher Q values.

Three-component seismic refraction data were recorded in northwestern Arizona in the Transition Zone between the Colorado Plateau and Basin and Range provinces. A 35.4 km array received shots from both these provinces. Seismograms from the southwest shots show two prominent reflections, indicating a reflector about 20 km deep and Moho depths of 26.5-29 km in the Basin and Range and 29-31 km in the Transition Zone. A weak PmP from the northeast suggests the crust or Moho in the Colorado Plateau has different characteristics than in the Basin and Range. Raytracing yields Pn and Sn velocities of 7.95 km/s and 4.59 km/s for the Transition Zone and shows evidence of laterally increasing Pn and Sn velocities toward the Basin and Range and the Colorado Plateau. Clear Pg and Sg arrivals reveal a low Poisson's ratio of 0.217 for the upper crust of the Colorado Plateau. (edc)

Studies are conducted in a number of areas pertinent to seismic discrimination. Attempts are made to check the efficiency of the Pn-Rayleigh discriminant found by McEvilly and Peppin (1972); results are not favorable for the use of this discriminant. Rather, a discriminant based on the excitation of Pg and Sg (or Lg), investigated by others, is found to be quite effective. Analyses of close-in accelerograms is attempted with the view toward application of moment tensor analysis. Results show that recent studies are still in significant disagreement. An attempt is made to investigate a seismic discriminant based on Pn alone. A set of Green's functions and data for small explosions have been assembled for application of moment tensor analysis. Peripheral studies include source studies of Basin and Range earthquakes and a study of Rayleigh wave dispersion on the test site.

It has long been recognized that the Earth provides a virtually indestructible full duplex path for communicating with hard buried facilities. Work on the subject has highlighted estimates of channel capacity for communicating in competent rock, as well as the performance of specific hardware and coding at short and long ranges. There is a need to determine the information capacity for communicating seismically in a landform suitable for basing MX. Of paramount interest is the information rate for communicating seismically in deep, dry alluvial valleys of the Basin and Range Province, the leading landform for MX basing. To this end, we have established the maximum information rate for sites in Railroad Valley, Steptoe Valley, and Jackass Flats, Nevada over a range of source strengths, bandwidths, and distances.

A study was made of the open literature on the geologic structure of the Basin and Range Province of the western United States. Based on this study, an attempt was made to derive a model of a typical basin for use in estimating the seismic ground motion characteristics of alluvial basins in the designated MX deployment area. Among the topics investigated are dimensions and structure of an average basin and characteristic seismic velocities in the basin interiors. In addition, many of the basins are expected to show significant variations from a typical structure and these variations are discussed. (Author)

Earlier study of Great Basin structure using surface waves have been extended to include the Southern Basin and Range of Arizona, and the Volcanic Plateau of Northern Nevada and Southern Oregon. The crust of the Southern Basin and Range is slightly thinner than that of the Great Basin while the mantle structure is similar. The Volcanic Plateau has a thicker crust (based on refraction data) than the Great Basin while the mantle lid zone is either thin or absent. (Author), Prepared in cooperation with Scripps Institution of Oceanography, La Jolla, CA. Inst. of Geophysics and Planetary Physics.

Four major study areas were selected to carry out detailed field and laboratory investigations of calcium carbonate cementation. These four study areas include: (1) selected alluvial basins in the southern Basin and Range Province of Arizona. Major characteristics include low-carbonate parent material, open but poorly integrated basins, tectonic stability, areas of active aggradation, and wide variations in alluvium texture; (2) Selected alluvial basins along the Colorado River in western Arizona. Major characteristics include high-carbonate parent material, open drainage basins, active dissection, and coarse-grained alluvium; (3) The Las Vegas alluvial basins in southern Nevada. Major characteristics include high-carbonate parent material, numerous geomorphic surface, open and closed drainage basins, and variable textures of alluvium; and (4) Selected basins in central Nevada. Major characteristics include variable carbonate content in parent materials, tectonically active, closed and open basins, and variable textures of parent materials.

The present study is concerned with production, transport and deposition of gravel in fluvial systems in hot arid regions. It attempts a definition of the variables affecting gravel origin, transport and deposition, assessment of significant changes in texture after deposition and evaluation of the composition of gravel buried in the upper alluvial section of depositional basins. The arid gemorphic environment is characterized by low precipitation, low rates of chemical weathering in most lithologic environments, high rates of mechanical weathering, scant vegetation and slow and sporadic soil development. General climate-process framework places most hot deserts in regions receiving less than 150 mm/yr of mean annual precipitation. Major geomorphic processes and events, occurring in rocky deserts are: mechanical weathering; debris flows and wash on hillslopes; free wind activity, precipitation of salts in fractured and elastic rocks and soils, and floods. Differential areal geomorphic activity and differential runoff-sediment contribution are very strongly emphasized in the arid environment. (Author), See also Volume 2, AD-A069 729. Original contains color plates: All DDC reproductions will be in black and white.

The effects of basin shape upon strong ground motion in shallow alluvial basins is examined for a series of simple, geometric basins. The resulting psuedovelocity response spectra contour maps form the basis for the analysis of realistic basin models to be presented in the final report. (Author)

This report summarizes efforts to simulate the characteristics of regional seismic phases from earthquakes and explosions. The objective is to use computer generated seismograms to aid our understanding of the origin of regional phases and to examine possible discriminants in regional recordings from earthquakes and explosions. This involves four distinct studies. First, the source-depth dependence of the phase Lg is examined. It is found that the depth dependence of synthetic Lg for double-couple sources can be explained by changes in material properties over crustal depths combined with radiation pattern effects for S-waves radiated with the phase velocities appropriate to Lg. The second effort reported is a study for the Basin and Range, most of the energy is trapped above an intermediate crustal reflector, whereas eastern United States and Eurasian crustal structures Lg was found to be a guided wave between the earth's surface and the Moho. third, differences in the characteristics of Lg radiated from earthquakes and explosions. Finally, the behavior of Lg codas as they are transmitted across boundaries between two different crustal structures.

Geophysics is used to assist exploration for bulk minable gold deposits, particularly over pediments. It is employed for mapping thickness of alluvium and Tertiary valley fill, for mapping covered structures, and for identifying alteration zones. In addition to potential field and seismic methods, three different electrical and electromagnetic methods are frequently used, resistivity-induced polarisation, controlled source audiomagnetotellurics, and time domain EM. A review and comparison of the principles of these methods, illustrated by case histories is given., Geophysics is used to assist exploration for bulk minable gold deposits, particularly over pediments. It is employed for mapping thickness of alluvium and Tertiary valley fill, for mapping covered structures, and for identifying alteration zones. In addition to potential field and seismic methods, three different electrical and electromagnetic methods are frequently used, resistivity-induced polarisation, controlled source audiomagnetotellurics, and time domain EM. A review and comparison of the principles of these methods, illustrated by case histories is given.

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.

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.

The Pantano Formation comprises 1,250 m of alluvial, fluvial, lacustrine, and volcanic rocks deposited in a basin formed in response to regional extension during mid- Tertiary time in southeastern Arizona. During deposition, the locations and composition of sediment source areas varied as contemporaneous uplift occurred adjacent to the basin. The lower half of the formation was deposited as alluvial fans that prograded northward, westward, and southward; the upper half was deposited during southwestward retreat of alluvial fan deposition and the onset of lacustrine deposition. An andesite flow separates the two depositional regimes. Radiometric dates of 24.4 ± 2.6 m.y. B.P. for the andesite and 36.7 ± 1.1 m.y. B.P. for a rhyolitic tuff disconformably underlying the formation indicate that deposition occurred during Oligocene to early Miocene time. Proper stratigraphic sequencing and description, paleocurrent analysis, and gravel provenance study aided in understanding the depositional history of the formation.

Two particular source regions, Lake Superior and the Nevada Test Site are documented in detail using available geological and geophysical observations. Each is discussed individually in relation to its setting in the prevailing regional crust and upper mantle structure of the mid-continent and the Basin and Range respectively. Comparison of the two source areas indicates that they are markedly different from one another not only at shallow depths but throughout the upper mantle as well. Location accuracies for events at both sites are quite comparable, however, a large bibliography documents the extensive literature relevant to Lake Superior and the Nevada Test Sites. (Author)

Most deposits are concentrated in separate, well-defined metallogenic provinces: Proterozoic conglomerates and unconformity-related deposits in the Blind River-Elliot Lake and Athabasca Basin areas of Canada; Upper Palaeozoic and Mesozoic tabular sandstone deposits in the Colorado Plateau; Tertiary roll-front deposits in the Rocky Mountain and Intermontane Basins and the Gulf Coastal province; volcanogenic deposits in the Basin and Range province; and uraniferous phosphorites in Tertiary sediments in Florida, Georgia, North and South Carolina and Idaho's Permian Phosphoria Formation. Most seem to have been associated with volcanic activity related to the development of the North American plate's western margin, with the south and west margin of the Canadian Shield at the leading edge of source development and mineralisation. Some provinces include related Cu, Au, Mo, Ni, Ag, Th and V in economic quantities., Most deposits are concentrated in separate, well-defined metallogenic provinces: Proterozoic conglomerates and unconformity-related deposits in the Blind River-Elliot Lake and Athabasca Basin areas of Canada; Upper Palaeozoic and Mesozoic tabular sandstone deposits in the Colorado Plateau; Tertiary roll-front deposits in the Rocky Mountain and Intermontane Basins and the Gulf Coastal province; volcanogenic deposits in the Basin and Range province; and uraniferous phosphorites in Tertiary sediments in Florida, Georgia, North and South Carolina and Idaho's Permian Phosphoria Formation. Most seem to have been associated with volcanic activity related to the development of the North American plate's western margin, with the south and west margin of the Canadian Shield at the leading edge of source development and mineralisation. Some provinces include related Cu, Au, Mo, Ni, Ag, Th and V in economic quantities.

The paper is divided into six sections: Introduction; Geology; Potential host media for radioactive waste; Quaternary tectonism; Ground-water hydrology; and Mineral and energy resources. Thirty-four metallic mining districts, or parts thereof, are located in the region. Small tonnages of ore, valued at less than a few million dollars, have been produced from numerous precious metal and fewer base metal deposits. Nonmetallic or industrial mineral and rock occurrences are widely scattered throughout the region; excluding construction materials, none of these commodities has been produced on a sustained basis. In San Bernardino County, sodium chloride and calcium chloride have been produced from Bristol and Cadiz Lakes, and salt has been extracted from Danby Lake. Large identified resources of gypsum exist in eastern Riverside County., The paper is divided into six sections: Introduction; Geology; Potential host media for radioactive waste; Quaternary tectonism; Ground-water hydrology; and Mineral and energy resources. Thirty-four metallic mining districts, or parts thereof, are located in the region. Small tonnages of ore, valued at less than a few million dollars, have been produced from numerous precious metal and fewer base metal deposits. Nonmetallic or industrial mineral and rock occurrences are widely scattered throughout the region; excluding construction materials, none of these commodities has been produced on a sustained basis. In San Bernardino County, sodium chloride and calcium chloride have been produced from Bristol and Cadiz Lakes, and salt has been extracted from Danby Lake. Large identified resources of gypsum exist in eastern Riverside County.

Results of regional analyses of precious metal habits in Arizona ores lead to interpretations of a fundamental ore control related to geographic location that corresponds to crustal contrasts. The numerous kinds of Laramide ores, which include porphyry copper deposits of this southern cordillera region, appear to be phenomena of a specific crustal lithology characterised by a basement of Proterozoic turbidites and (an interpreted) lower crust of amphibolites. Whereas plate tectonic mechanisms may have triggered evolution of these ores, it is hypothesised that crustal setting and crustal composition are more profound influences on metallogenesis., Results of regional analyses of precious metal habits in Arizona ores lead to interpretations of a fundamental ore control related to geographic location that corresponds to crustal contrasts. The numerous kinds of Laramide ores, which include porphyry copper deposits of this southern cordillera region, appear to be phenomena of a specific crustal lithology characterised by a basement of Proterozoic turbidites and (an interpreted) lower crust of amphibolites. Whereas plate tectonic mechanisms may have triggered evolution of these ores, it is hypothesised that crustal setting and crustal composition are more profound influences on metallogenesis.

The geochemistry of fluorine and chlorine in igneous rocks is important because they are pathfinder elements for fluorite and fluorophile metals (Be, U, Ta, Sn and perhaps Mo and W). Three types of granite are distinguished: fluorine-poor granitoids, fluorine-rich Precambrian granites and a large group of granitoids with moderate fluorine contents. The differences are attributed to magma contamination by, or generation from, a comparatively fluorine-rich reservoir in the continental crust. The geochemistry and metallogenetic implications are discussed., The geochemistry of fluorine and chlorine in igneous rocks is important because they are pathfinder elements for fluorite and fluorophile metals (Be, U, Ta, Sn and perhaps Mo and W). Three types of granite are distinguished: fluorine-poor granitoids, fluorine-rich Precambrian granites and a large group of granitoids with moderate fluorine contents. The differences are attributed to magma contamination by, or generation from, a comparatively fluorine-rich reservoir in the continental crust. The geochemistry and metallogenetic implications are discussed.