Earth Sciences Commons^™

Discovery Of Two Additional Prosimian Primate Families (Omomyidae, Lorisidae) In The African Oligocene, Elwyn L. Simons, Thomas M. Bown, D. Tab Rasmussen

United States Geological Survey: Staff Publications

Three new specimens reported here are referable to the Omomyidae and Lorisidae, and represent only the second and third prosimian primates found in the Oligocene rocks of the Fayum, Egypt. The Fayum omomyid extends the range of the Omomyidae into Africa, while the Fayum lorisid is the oldest record of the Lorisidae world-wide. Afrotarsius established ?Tarsiidae as a third prosimian family present in Oligocene rocks of the Fayum region of Egypt (Simons & Bown, 1985). These new occurrences significantly reorient paleogeographic study of primate origins. In a fauna famed for the presence of about a thousand specimens of early Anthropoidea-viz. …

Sedimentation In A Blast-Zone Lake At Mount St. Helens, Washington-Implications For Varve Formation, Roger Y. Anderson, Edward Nuhfer, Walter E. Dean

United States Geological Survey: Staff Publications

Sediment collected in traps in a newly formed lake in the blast-impact area at Mount St. Helens recorded a sediment yield that is about two orders of magnitude greater than for comparable basins with vegetation and similar precipitation. Most sediment was mobilized by storms and run off at the onset of the wet season. The sedimentation response to strongly seasonal precipitation, in the absence of vegetation, produced turbidites and graded annual couplets. The style of sedimentation suggests an alternate mechanism for the formation of long sequences of graded clastic varves.

Magnetic Polarity Stratigraphy And Mammalian Fauna Of The Deseadan (Late Oligocene-Early Miocene) Salla Beds Of Northern Bolivia, Bruce J. Macfadden, Kenneth E. Campbell Jr., Richard L. Cifelli, Oscar Siles, Noye M. Johnson, Charles W. Naeser, Peter K. Zeitler

United States Geological Survey: Staff Publications

The Salla Beds contain a rich assemblage of Deseadan mammals that traditionally has been considered of early Oligocene age. These deposits, located 90-100 km SE of La Paz, Bolivia, consist of more than 540 m of principally fluviatile clays and silts with numerous interbedded tuffs. Paleomagnetic samples were collected from 104 sites spaced at stratigraphic intervals of about 6 m. As a result of thermal demagnetization (at 400°Co r greater), unambiguous polarities were determined for 76 of the 104 originally sampled ites. The pattern of reversals, stage of evolution of the fossils, and preliminary isotopic dates (including a K/Ar age …

Hydraulic Fracturing Stress Measurements At Yucca Mountain, Nevada, And Relationship To The Regional Stress Field, J. M. Stock, J. H. Healy, S. H. Hickman, M. D. Zoback

United States Geological Survey: Staff Publications

Hydraulic fracturing stress measurements and acoustic borehole televiewer logs were run in holes USW G-1 and USW G-2 at Yucca Mountain as part of the Nevada Nuclear Waste Storage Investigations for the U.S. Department of Energy. Eight tests in the saturated zone, at depths from 646 to 1288 m, yielded values of the least horizontal stress S_h that are considerably lower than the vertical principal stress S_v. In tests for which the greatest horizontal principal stress S_H could be determined it, was found to be less than S _ν, indicating a normal faulting stress regime. …

On The Classification Of The Early Tertiary Erinaceomorpha (Insectivora, Mammalia), Michael J. Novacek, Thomas M. Bown, David Schankler

United States Geological Survey: Staff Publications

Definitions are provided for three Early Tertiary families of Erinaceomorpha. The family Dormaaliidae includes Dormaalius, Macrocranion, Scenopagus, Ankylodon, Crypholestes, Sespedectes, and Proterixoides.

Permeability Versus Depth In The Upper Oceanic Crust' In Situ Measurements In Dsdp Hole 504b, Eastern Equatorial Pacific, Roger N. Anderson, Mark D. Zoback, Stephen H. Hickman, Robin L. Newmark

United States Geological Survey: Staff Publications

In situ permeabilities measured within the upper kilometer of oceanic crust in hole 504B on the south flank of the Costa Rica Rift decrease exponentially from 10^-13 to 10^-14 m² in layer 2A (the upper 150m) to 10 ^-15 to 10^-17 m² in layer 2B (150-550 m into basement), and to 10^-17 m² and lower in layer 2C (deeper than 550 m). We estimate the permeability (k) versus depth (z) to vary as k(z)=0.11e^(-z/50)x 10^-12 m². If this permeability versus depth function is representative of …

A Frotarsius Chatrathi, First Tarsiiform Primate (? Tarsiidae) From Africa, Elwyn L. Simons, Thomas M. Bown

United States Geological Survey: Staff Publications

Tarsiiform primates have long been regarded as a Laurasian group, with an extensive fossil record in the Eocene of North America and EuropeI and two important but less well-known records from Asia.

In Situ Stress, Natural Fracture Distribution, And Borehole Elongation In The Auburn Geothermal Well, Auburn, New York, Stephen H. Hickman, John H. Healy, Mark D. Zoback

United States Geological Survey: Staff Publications

Hydraulic fracturing stress measurements and a borehole televiewer survey were conducted in a 1.6-km-deep well at Auburn, New York. This well, which was drilled at the outer margin of the Appalachian Fold and Thrust Belt in the Appalachian Plateau, penetrates approximately 1540 m of lower Paleozoics edimentary rocks and terminates 60 m into the Precambrian marble basement. Analysis of the hydraulic fracturing tests indicates that the minimum horizontal principal stress increases in a nearly linear fashion from 9.9 ± 0.2 MPa at 593 m to 30.6 ± 0.4 MPa at 1482 m. The magnitude of the
maximum horizontal principal stress …

An Evaluation Of Uranium-Series Dating Of Fossil Echinoids From Southern California Pleistocene Marine Terraces, Daniel R. Muhs, Los Angeles County Museum Of Natural History, Los Angeles, Ca

United States Geological Survey: Staff Publications

Fossil sea urchins (Strongylocentrotus) from Pleistocene marine terraces on the southern California Channel Islands have been dated by the uranium-series method in order to test the suitability of echinoids for dating marine terraces. Results indicate that urchin plates and spines do not behave as closed systems with respect to both uranium and thorium. Calculated ages based on these data do not agree with uranium-series ages (120,000 and 127,000 yrs) obtained previously from corals from the same localities. Thus, fossil sea urchins (Strongylocentrotus) are not considered suitable for uranium-series dating of Pleistocene marine terrace deposits.

Soils And The Location Of Cacao Orchards At A Maya Site In Western Belize, Daniel R. Muhs, Robert R. Kautz, J. Jefferson Mackinnon

United States Geological Survey: Staff Publications

Cacao was one of the most important crops of the lowland Maya. Ethnohistoric sources document that the Postclassic-Colonial Period Maya settlement of Tipu in western Belize was an important cacao-growing center, yet evidence of where the cacao was grown is not apparent. We analysed the suitability of floodplain, terrace, and bedrock soils for cacao cultivation. Our results indicate that the soils most likely to have been used for cacao growth were those on the modem floodplain of the Macal River, based on their suitable physical and chemical properties. In addition, buried stone walls of Late Classic or Postclassic age that …

Well Bore Breakouts And In Situ Stress, Mark D. Zoback, Daniel Moos, Larry Mastin, Roger N. Anderson

United States Geological Survey: Staff Publications

The detailed cross-sectional shape of stress induced well bore breakouts has been studied using specially processed ultrasonic borehole televiewer data. We show breakout shapes for a variety of rock types and introduce a simple elastic failure model which explains many features of the observations. Both the observations and calculations indicate that the breakouts define relatively broad and flat curvilinear surfaces which enlarge the borehole in the direction of minimum horizontal compression. This work supports the hypothesis that breakouts result from shear failure of the rock where the compressive stress concentration around the well bore is greatest and that breakouts can …

The Variability Of Holocene Climate Change: Evidence From Varved Lake Sediments, Walter E. Dean, J. Platt Bradbury, Roger Y. Anderson, Cathy Barnosky

United States Geological Survey: Staff Publications

Varved sediments from a lake near the present forest-prairie border in northwestern Minnesota provide an annual record of climate change for the last 10,400 years. Climate-sensitive mineral, chemical, and biological components show that the mid-Holocene dry interval between 8500 and 4000 years ago is asymmetrical and actually consists of two distinct drier pulses separated by a moister interval that lasted about 600 years. Cyclic fluctuations with periods of several hundred years were abrupt and persistent throughout the Holocene and are most clearly recorded within the two drier pulses.

Sinking Of Volcanic Ash In Uncompacted Sediment In Williams Lake, Washington, Roger Y. Anderson, Edward Nuhfer, Walter E. Dean

United States Geological Survey: Staff Publications

Volcanic ash from the eruption of Mount St. Helens on 18 May 1980 fell into Williams Lake in eastern Washington and was temporarily suspended at the sediment-water interface. After several months of compaction, the ash layer broke up and sank into lower density uncompacted lake sediment. Stratigraphic time displacements of several hundred years and a failure to recognize discontinuous ash layers in sediment cores are possible consequences of this process.

Geohydrology Of The High Plains Aquifer In Parts Of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, And Wyoming, Edwin D. Gutentag, Frederick J. Heimes, United States Geological Survey, Richard R. Luckey, John B. Weeks

United States Geological Survey: Staff Publications

The High Plains aquifer, which underlies about 174,000 square miles in parts of eight states, is the principal source of water in one of the Nation's major agricultural areas. About 170,000 wells pump water from the aquifer to irrigate about 13 million acres in the High Plains. In 1978, the United States Geological Survey began a regional study of the High Plains aquifer to provide geohydrologic data and computer models of the aquifer needed to evaluate the effects of ground-water development. This report describes the geohydrology of the High Plains aquifer. The High Plains aquifer consists mainly of hydraulically connected …

Gradual Phyletic Evolution At The Generic Level In Early Eocene Omomyid Primates, Kenneth D. Rose, Thomas M. Bown

United States Geological Survey: Staff Publications

Analysis of dental morphology in over 600 stratigraphically controlled specimens of tarsier-like primates from early Eocene strata in Bighorn Basin, Wyoming, provides important new data for understanding the tempo and mode of evolution in primates.

Correlation Of The Middle Eocene Kellogg Shale Of Northern California, John A. Barron, David Bukry, Richard Z. Poore

United States Geological Survey: Staff Publications

The Kellogg Shale of northern California has traditionally been considered to be late Eocene in age on the basis of benthic foraminifer, radiolarian, and diatom correlations. The 30-m-thick Kellogg section exposed west of Byron, California, however, contains middle Eocene planktonic foraminifers (Zone P12), coccoliths (Subzones CP13c and CP14a), silicoflagellates (Dictyocha hexacantha Zone), and diatoms. Quantitative studies of the silicoflagellates and diatoms show a general cooling trend through the section which is consistent with paleoclimatic trends for this part of the middle Eocene (ca. 42-45 Ma) from elsewhere in the world. Seven new silicoflagellate taxa (Corbisema angularis. C, exilis, …

Hydrochemical Data For The Truckee River Drainage System, California And Nevada, Larry V. Benson

United States Geological Survey: Staff Publications

Abstract

Surface-water samples were collected from the Truckee River drainage system during 1975, 1976, and 1981. Data resulting from chemical analyses of these samples, as well as certain other previously unpublished data, are tabulated in this report. The report contains the following hydrochemical data:

1. Chemical composition of 21 tributaries to Lake Tahoe and the Truckee River upstream from Farad, California (May and October 1971, and June 1972).

2. Chemical composition of the Truckee River at Tahoe City (January 1968-January 1975) and at Farad, California (January 1968-June 1980), and of the Little Truckee River upstream from Stampede Reservoir, California (January …

Monitoring Velocity Variations In The Crust Using Earthquake Doublets: An Application To The Calaveras Fault, California, G. Poupinet, W. L. Ellsworth, J. Frechet

United States Geological Survey: Staff Publications

We present a technique that greatly improves the precision in measuring temporal variations of crustal velocities using an earthquake doublet, or pair of microearthquakes that have nearly identical waveforms and the same hypocenter and magnitude but occur on different dates. We compute differencesin arrival times between seismograms recorded at the same station in the freqency domain by cross correlation of short windows of signal. A moving-window analysis of the entire seismograms, including the coda, gives δ(t), the difference in arrival times versus running time along the seismogram. The time resolution of the method is an order of magnitude better than …

The Chemical Composition Of Lakes In The North-Central United States, Eville Gorham, Walter E. Dean, Jon E. Sanger

United States Geological Survey: Staff Publications

Lake waters of the north-central U.S.A. are classified into five groups, based on increasing specific conductivity and changes in ionic composition from east to west, from Wisconsin through Minnesota to North and South Dakota. The most dilute group of waters has specific conductivities <29 μnhos x cm^-1 at 25°C; the most concentrated group has specific conductances that range from 7,000 to 73,000 μmhos. As conductivity increases all major ions increase, but there is a shift in cation dominance from Ca²⁺ to Mg²⁺ to Na⁺, and in anion dominance from HCO₃^- to SO₄^2-. This shift …

Paleotemperature Oscillations In The Middle And Late Miocene Of The Northeastern Pacific, John A. Barron, Gerta Keller

United States Geological Survey: Staff Publications

The paleoclimatic and paleoceanographic history of the Middle and Late Miocene marginal eastern North Pacific as been studied in a north-to-south transect encompassing DSDP Site 173, the Newport Beach surface section, and DSDP Site 470, based on quantitative diatom and planktic foraminiferal analyses. Fourteen cold and 12 warm events that show close agreement with other microfossil studies as well as oxygen isotope records from low-latitude Pacific sites have been identified. Hiatuses are recognized at 7 to 6.5 Ma. 9.8 to 8.5 Ma, and 12 to 11 Ma at the three reference localities, and they correspond to widely recognized deep-sea hiatuses …

A Hydrochemical Reconnaissance Study Of The Walker River Basin, California And Nevada, Larry Benson, R. J. Spencer

United States Geological Survey: Staff Publications

During 1975 and 1976, a large number of water and sediment samples were collected from the Walker River Basin. Additional surface water samples were collected during 1980 and 1981. Data are given herein for chemical analyses of snowmelt, tributary, river, spring, well, lake, reservoir, lake sediment pore fluid, tufa, lake and river sediment samples. These data provide the basis for consideration of processes which govern the chemical evolution of large closed basin hydrologic systems in the Basin and Range Province of the Southwestern United States.

The Walker River Basin, a part of the Basin and Range Province, is located i~ …

Reassessment Of The Rates At Which Oil From Natural Sources Enters The Marine Environment, Keith A. Kvenvolden, John W. Harbaugh

United States Geological Survey: Staff Publications

Previous estimates of the world-wide input of oil to the marine environment by natural seeps ranged from 0 ·2 to 6 ·0 million (metric) tonnes per year with a 'best estimate' of 0 ·6 million tonnes per year. Based on considerations of the availability of oil for seepage from the world's known and assumed oil resources, we believe that the world-wide natural oil seepage over geological time should be revised to about 0 ·2 million tonnes per ),ear with a range upward or downward of a factor of ten leading to estimates between 0 ·02 and 2 million tonnes per …

In Situ Studies Of Velocity In Fractured Crystalline Rocks, Daniel Moos, Mark D. Zoback

United States Geological Survey: Staff Publications

A study of the effects of macroscopic fractures on P and S wave velocities has been conducted in four wells drilled in granitic rock to depths between 0.6 and 1.2km. The effect of macroscopic fractures is to decrease both V_p, and V_s and increase V_p/V_s. In wells with a relatively low density of macroscopic fractures, the in situ velocitiys similar to that of saturated core samples under confining pressure in the laboratory, and there is a clear correlation between zones with macroscopic fractures and anomalously low velocities. In wells with numerous macroscopic fractures, …

State Of Stress In The Lithosphere, Mark D. Zoback

United States Geological Survey: Staff Publications

Recent estimates of the magnitude and orientation of lithospheric stresses are
reviewed. Data come from a variety of sources including earthquake focal mechanisms, fault slip data, young volcanic dikes and feeders, in-situ stress measurements at depth, lithospheric flexure models, microstructure paleopiezometry, and consideration of constraints on maximum stress differences from laboratory-determined friction and flow laws.

Threshold Friction Velocities And Rupture Moduli For Crusted Desert Soils For The Input Of Soil Particles Into The Air, Dale A. Gillette, John Adams, Daniel R. Muhs, Rolf Kihl

United States Geological Survey: Staff Publications

Desert soils having clay crusts, mostly from the Mojave Desert, were tested for threshold friction velocity (the friction velocity at which soil erosion begins) with an open-bottomed wind tunnel. The soils were also tested for content of clay, water-soluble material, calcium carbonate, organic material, mineralogy of clay and of salts, soil moisture, modulus of rupture, and crust thickness. If no loose material existed on the soil surface, crusts having modulus of rupture greater than 0.7 bar and crust thickness of 0.7 cm to 0.3 cm were effective in protecting against wind erosion. Disturbed clay crusts having modulus of rupture before …

Diatom Biostratigraphy And Paleoecology Of The Type Section Of The Luisian Stage, Central California, Jack G. Baldauf, John A. Barron

United States Geological Survey: Staff Publications

Diatoms from the type section of the Luisian Stage in central California correlate with the lowermost part of the Denticulopsis lauta Zone through the lower part of subzone "a" of the Denticulopsis hustedtii –D. lauta Zone and are early Middle Miocene in age (about 16.0 to 14.0 Ma}. Rocks assigned to the Luisian Stage by benthic foraminifers elsewhere in California exhibit little diachroneity in terms of diatom biostratigraphy; however, detailed studies of boundaries have not been done. Planktic diatoms dominate the assemblages, although an increase in benthic and tychopelagic diatoms in the overlying Hames Member of the Monterey Formation probably …

Permeability, Underpressures, And Convection In The Oceanic Crust Near The Costa Rica Rift, Eastern Equatorial Pacific, Roger N. Anderson, Mark D. Zoback

United States Geological Survey: Staff Publications

In situ permeability and pore pressures were measured 200 m deep beneath the top of the oceanic crust at DSDP site 504B. These measurements have relevance for the transition from convective to conductive heat flow on the south flank of the Costa Rica Rift. Conventional 'slug' and constant rate injection tests were made below a hydraulic packer set at various depths in the hole. The packer was first set in a massive flow unit 37 m below the sediment-basement interface. The bulk permeability of the 172.5m of pillow basalts and basaltic flows below the packer was found to be about …

The Distribution Of Natural Fractures And Joints At Depth In Crystalline Rock, Donald A. Seeburger, Mark D. Zoback

United States Geological Survey: Staff Publications

This paper presents the results of studies of the natural fracture distribution encountered in 10 test wells drilled in three areas of the United States. Seven of the wells were drilled to depths of 200-250m, while three were drilled to depths of about 1 km. Using an ultrasonic borehole televiewer, fracture depths, strikes, and dips were determined. Steeply dipping fractures were found throughout each of the wells, and in general, few horizontal fractures were observed. Statistically significant fracture pole concentrations were found for each well which were basically invariant with depth, although some variation of fracture orientation with depth was …

Aftershocks Of The Coyote Lake, California, Earthquake Of August 6, 1979' A Detailed Study, P. Reasenberg, W. L. Ellsworth

United States Geological Survey: Staff Publications

Aftershock hypocenters and focal mechanism solutions for the Coyote Lake, California, earthquake reveal a geometrically complex fault structure, consisting of multiples lip surfaces. The faulting surface principally consists of two right stepping en echelon, northwest trending, partially overlapping, nearly vertical sheets and is similar in geometry to a slip surface inferred for the 1966 Parkfield, California, earthquake. The overlap occurs near a prominent bend in the surface trace of the Calaveras fault at San Felipe Lake. Slip during the main rupture, as inferred from the distribution of early aftershocks, appears to have been confined to a 14-km portion of the …

In Situ Study Of The Physical Mechanisms Controlling Induced Seismicity At Monticello Reservoir, South Carolina, Mark D. Zoback, Stephen Hickman

United States Geological Survey: Staff Publications

In two ~1.1-km-deep wells, the magnitudes of the principal in situ stresses, pore pressure, permeability, and the distribution of faults, fractures, and joints were measured directly in the hypocentral zones of earthquakes induced by impoundment of Monticello Reservoir, South Carolina. Analysis of these data suggests that the earthquakes were caused by an increase in subsurface pore pressure sufficiently large to trigger reverse-type fault motion on preexisting fault planes in a zone of relatively large shear stresses near the surface. The measurements indicated (1) near-critical stress differences for reverse-type fault motion at depths less than 200-300 m, (2) possibly increased pore …