Earth Sciences Commons^™

Age Estimates And Uplift Rates For Late Pleistocene Marine Terraces' Southern Oregon Portion Of The Cascadia Forearc, Daniel R. Muhs, Harvey M. Kelsey, Gifford H. Miller, Geoge L. Kennedy, Joseph F. Whelan, Galan W. Mcinelly

United States Geological Survey: Staff Publications

Marine terraces are prominent landforms along the southern Oregon coast, which forms part of the forearc region of the Cascadia subduction zone. Interest in the Cascadia subduction zone has increased because recent investigations have suggested that slip along plates at certain types of convergent margins is characteristically accompanied by large earthquakes. In addition, other investigations have suggested that convergent margins can be broadly classified by the magnitude of their uplift rates. With these hypotheses in mind, we generated new uranium series, amino acid, and stable isotope data for southern Oregon marine terrace fossils. These data, along with terrace elevations and …

The Style Of Late Cenozoic Deformation At The Eastern Front Of The California Coast Ranges, Carl M. Wentworth, Mark D. Zoback

United States Geological Survey: Staff Publications

The 1983 Coalinga earthquake occurred at the eastern boundary of the California Coast Ranges in response to northeast directed thrusting. Such movements over the past 2 Ma have produced Coalinga anticline by folding above the blind eastern tip of the Coalinga thrust zone. The 600-km length of the Coast Ranges boundary shares a common structural setting that involves westward upturn of Cenozoic and Cretaceou strata at the eastern front of the Coast Ranges and a major, southwest facing step in the basement surface beneath the western Great Valley. Like Coalinga anticline, Pliocene and Quaternary folding and faulting along the rest …

Cyclostephanos Lacrimis N. Sp. And Cyclostephanos Guatemalae N. Sp.: Two New Centric Diatoms From The Fossil Record Of Guatemala, Edward Theriot, J. Platt Bradbury

United States Geological Survey: Staff Publications

Two new species of Cyclostephanos are described from Pleistocene diatomites near Lago de Atitlan, Guatemala. In both species, radiating costae continue un- branched to the valve margin and the external expression of the single labiate process is an elongate pore on the mantle beneath a spine. Cyclostephanos lacrimis n. sp. is 7-75 jum in diameter and has no central area strutted processes. Each mantle strutted process is located within a marginal alveolus directly adjacent to a costa; this unique location is usually visible with light microscopy. C. guatemalae n. sp. is smaller (5-23 μm), with a single eccentrically-located strutted process …

Geochemical Evidence For Suppression Of Pelagic Marine Productivity At The Cretaceous/Tertiary Boundary, James C. Zachos, Michael A. Arthur, Walter E. Dean

United States Geological Survey: Staff Publications

The normal, biologically productive ocean is characterized by a gradient of the ¹³C /¹²C ratio from surface to deep waters. Here we present stable isotope data from planktonic and benthic microfossils across the Cretaceous/Tertiary boundary in the North pacific, which reveal a rapid and complete breakdown in this biologically mediated gradient. The fluxes of barium (a proxy for organic carbon) and CaCO, also decrease significantly at the time of the major marine plankton extinctions. The implied substantial reduction in oceanic primary productivity persisted for ~0.5 Myr before the carbon isotope gradient was gradually re-established. In addition, the …

State Of Stress And Modern Deformation Of The Northern Basin And Range Province, Mary Lou Zoback

United States Geological Survey: Staff Publications

Constraints on the current stress regime of the actively extending northern Basin and Range province are provided by deformation data (focal mechanisms and fault slip studies), hydraulic fracturing in situ stress measurements, borehole elongation ("breakouts") analyses, and alignment of young volcanic vents. The integrated data indicate significant variations both in principal stress orientations and magnitudes. An approximately E-W least principal stress direction appears to characterize both the eastern and western margins of the Basin and Range province, whereas in the active interior parts of the province extension occurs in response to a least principal stress oriented NW to N60 °W. …

The Uranium-Trend Dating Method: Principles And Application For Southern California Marine Terrace Deposits, Daniel R. Muhs, John N. Rosholt, Charles L. Bush

United States Geological Survey: Staff Publications

Uranium-trend dating is an open-system method for age estimation of Quaternary sediments, using disequilibrium in the ²³⁸U–²³⁴U–²³⁰Th decay series. The technique has been applied to alluvium, colluvium, loess, till, and marine sediments, in this study we tested the U-trend dating method on calcareous marine terrace deposits from the Palos Verdes Hills and San Nicolas Island, California. Independent age estimates indicate that terraces in these areas range from –80 ka to greater than 1.0 Ma. Two low terraces on San Nicolas Island yielded U-trend plots that have a clustered array of points and the ages of …

The Cajon Pass Scientific Drilling Experiment: Overview Of Phase 1, Mark D. Zoback, Leon T. Silver, Thomas Henyey, Wayne Thatcher

United States Geological Survey: Staff Publications

The Cajon Pass Scientific Drilling Project is a broad, interdisciplinary experiment involving over two dozen principal scientists. Phase I of drilling, coring and down hole experimentation began Dec. 8, 1986 and ended April 2, 1987 with the hole at a depth of 2115 m, 82 m of core recovered and a wide range of down hole experiments successfully completed. In this paper we briefly outline the scientific motivation for the project and provide an overview of the scientific program. We also indicate some of the varied research areas in the earth sciences where data obtained in this experiment will provide …

Continuation Of A Deep Borehole Stress Measurement Profile Near The San Andreas Fault 1. Hydraulic Fracturing Stress Measurements At Hi Vista, Mojave Desert, California, Stephen H. Hickman, Mark D. Zoback, John H. Healy

United States Geological Survey: Staff Publications

Hydraulic fracturing stress measurements were made in a 592-m-deep well at Hi Vista, California, 32 km from the San Andreas fault in the western Mojave Desert. The relative magnitudes of the horizontal principal stresses and the calculated overburden stress indicate that the stress regime at this site is transitional between thrust faulting and strike-slip faulting. The azimuths of the induced hydraulic fractureast Hi Vista exhibit considerable scatter, and the indicated direction of them aximum horizontal principal stress ranges from north-northeast to northwest. The measured magnitudes of the horizontal principal stresses and the horizontal deviatoric stress in this well are less …

A Statistical Evaluation Of Formation Disturbance Produced By Well-Casing Installation Methods, Roger H. Morin, Denis R. Leblanc, Warren E. Teasdalea

United States Geological Survey: Staff Publications

Water-resources investigations concerned with contaminant transport through aquifers comprised of very loose, unconsolidated sediments have shown that small-scale variations in aquifer characteristics can significantly affect solute transport and dispersion. Various sampling and borehole-logging techniques have been integrated into these studies to detect and measure detailed formation changes through casing or well screen along the length of the borehole. Commonly, measurement accuracy and resolution have been limited by a borehole environment consisting of an annulus of disturbed sediments produced by the casinginstallation method.

Determining The Distribution Of Hydraulic Conductivity 1n A Fractured Limestone Aquifer By Simultaneous Injection And Geophysical Logging, Roger H. Morin, Alfred E. Hess, Frederick L. Paillee

United States Geological Survey: Staff Publications

i\ field technique for assessing the vertical distribution of hydraulic conductivity in an aquifer was applied to a fractured carbonate formation in southeastern Nevada. The technique combines the simultaneous usc of fluid injection and geophysical logging to measure in situ vertical distributions of fluid velocity and hydraulic head down the borehole; these data subsequently are analyzed to arrive at quantitative estimates of hydraulic conductivity across discrete intervals in the aquifer. The diagnostic capabilities of the analysis were found to be constraincd by the accuracy and resolution of the logging tools as well as by the hydraulic characteristics of the formation. …

Hydraulic Fracturing In Situ Stress Measurements To 2.1 Km Depth At Cajon Pass, California, John H. Healy, Mark D. Zoback

United States Geological Survey: Staff Publications

Stress measurements to 2.1km reveal stress changes with depth that cannot be explained by an elastic response to uniform crustal strain. The data at about 1 km depth suggest that the stress is limited by the frictional strength of rock and is perturbed at greater depths by faults which intersect the borehole. The stress
data indicate that there is little or no right-lateral shear stress acting on planes parallel to the San Andreas Fault.

Neogene And Quaternary Lacustrine Diatom Biochronology, Western Usa, William Krebs, J. Platt Bradbury, Edward Theriot

United States Geological Survey: Staff Publications

Neogene and Quaternary lacustrine diatomaceous deposits are numerous in the western United States, particularly in the Great Basin. Some of these sediments are interbedded with volcanic rocks that have been dated radiometrically or by the fssion track method. Fossil lacustrine diatom floras can thus be arranged in geochronological order. By this means, a biochronological pattern of lacustrine diatom evolution has emerged: obligate nonmarine Actinocyclus Ehrenberg (Family Hemidiscaceae) appeared in the early Miocene and attained maximum diversity in the middle middle Miocene. A single species of non-marine Actinocyclus persisted to the end of the middle Miocene. Only two species of marine …

Diatoms And Tonsteins As Paleoenvironrnental And Paleodepositional Indicators In A Miocene Coal Bed, Costa Rica, J. David Sanchez, J. Platt Bradbury, Bruce F. Bohor, Donald A. Coates

United States Geological Survey: Staff Publications

Fresh-water diatoms are present in coal, and tonsteins (altered volcanic ash) are interbedded with the coal, in the Miocene Venado Formation on the southwest margin of the Limon Basin, in Provincia Alajuela, northern Costa Rica. The Venado Formation is composed of more than 300 m of mudstone, siltstone, sandstone, limestone, volcaniclastics, and coal beds. The coal beds are of unknown lateral extent and mainly occur in the middle part of the formation. The Pataste coal bed occurs near the middle of the formation and is divided into three parts by two tonstein layers. The abundance of biogenic opaline material (diatoms) …

Integration Of Channel And Floodplain Suites, Developmental Sequence And Lateral Relations Of Alluvial Paleosols, Thomas M. Bown, Mary J. Krause

United States Geological Survey: Staff Publications

The lower Eocene Willwood Formation of the Bighorn Basin, northwest Wyoming, consists of about 770 m of alluvial rocks that exhibit extensive mechanical and geochemical modifications resulting from Eocene pedogenesis. Willwood paleosols vary considerably in their relative degrees of maturity; maturity is defined as stage of development as a function of the amount of time required to form. Five arbitrary stages are proposed to distinguish these soils of different maturities in the Willwood Formation. Stage 1 soils, the least mature, are entisols; stage 2 and stage 3 soils are intermediate in maturity and are probably alfisols; and stage 4 and …

Stockwork Tungsten (Scheelite)-Molybdenum Mineralization, Lake George, Southwestern New Brunswick, Robert R. Seal Ii, Alan Clark, Charles Morrissy

United States Geological Survey: Staff Publications

Scheelite-molybdenite stockwork mineralization constitutes one component of the Lake George polymetallic (Sb-W-Mo-Au-base metal) deposit, a complex hydrothermal center of Late Silurian (ca. 412 m.y.) age in the Fredericton trough of the northern Appalachians. The stockwork, hosted by Silurian graywackes, in part calcareous, is spatially and temporally related to a postkinematic cupola of biotite monzogranite, and its formation overlapped in time with the emplacement of monzogranitic porphyry dikes. Mineralogical and textural evidence indicates that contact metamorphism associated with the cupola had ceased before the initiation of W-Mo mineralization and that it occurred, at pressures of less than 1.75 kb, in two …

15N/14N Variations In Cretaceous Atlantic Sedimentary Sequences: Implication For Past Changes In Marine Nitrogen Biogeochemistry, Greg H. Rau, Michael A. Arthur, Walter E. Dean

United States Geological Survey: Staff Publications

At two locations in the Atlantic Ocean (DSDP Sites 367 and 530) early to middle Cretaceous organic-carbon-rich beds ("black shales") were found to have significantly lower δ¹⁵N values (lower ¹⁵N/¹⁴N ratios) than adjacent organic-carbon-poor beds (white limestones or green claystones). While these lithologies are of marine origin, the black strata in particular have δ¹⁵N values that are significantly lower than those previously found in the marine sediment record and most contemporary marine nitrogen pools. In contrast, black, organic-carbon-rich beds at a third site (DSDP Site 603) contain predominantly terrestrial organic matter and have …

Genesis Of Marine Terrace Soils, Barbados, West Indies: Evidence From Mineralogy And Geochemistry, Daniel R. Muhs, Russell C. Crittenden, John N. Rosholt, Charles A. Bush, Kathleen C. Stewart

United States Geological Survey: Staff Publications

Well-developed, clay-rich soils dominated by interstratified kaolinite-smectite are found on the uplifted coral reef terraces on the island of Barbados. The reef limestone is unlikely to have been the soil parent material however, because it is 98 per cent CaCO, and geomorphic evidence argues against the 20 m of reef solution required to produce the soils by this process. The mineralogy of the sand, silt, and clay fractions of the soils, and trace element geochemistry, suggest that aeolian materials carried on the trade winds from Africa, volcanic ash from the island of St. Vincent, and quartz from Tertiary bedrock on …

Mesodictyon, A New Fossil Genus Of The Centric Diatom Family Thalassiosiraceae From The Miocene Chalk Hills Formation, Western Snake River Plain, Idaho, Edward Theriot, J. Platt Bradbury

United States Geological Survey: Staff Publications

Three new centric diatom species assigned to a new genus are described from Miocene lacustrine deposits of Idaho. Species of the new genus, Mesodictyon, have the areola cribrum in the middle of the loculus, strutted processes and radiating, non-fasciculated striae. The strutted processes of M. magnum (diameter 60-150 μm) have long (2-3 μm) tubular extensions. The strutted processes of M. fovis (diameter 14-80 μm) are in distinct pits near the junction of the face and mantle. The valve face of M. undulatum (diameter 10-44 μm) is weakly tangentially undulate. Preliminary evidence indicates that Mesodictyon has a wide geographic distribution …

Stable Isotope Compositions Of Fossil Mollusks From Southern California: Evidence For A Cool Last Interglacial Ocean, Daniel R. Muhs, T. Kurtis Kyser

United States Geological Survey: Staff Publications

Stable isotope compositions have been determined for modem mullusks and fossil mollusks collected from uplied marine terraces at three l d t i e s in southern California. By using a paleocliatic model that decouples the temperature and ice-volume signals in ocean water, ocean-water temperatures off southern California are estimated to have been -3.8 °C at ~85 ka, -3.0 °C at ~107 ka, and -2.2 °C at ~125 ka relative to present temperature. These results indicate rather cool conditions during the peak of the last interglacial stage at 125 ka and conflict with results from terrace faunal studies that suggest …

Lungfish Burrows In The Upper Triassic Chinle And Dolores Formations, Colorado Plateau, Russell F. Dubiel, Robert H. Blodgett, Thomas M. Bown

United States Geological Survey: Staff Publications

Vertical-to-inclined, cylindrical trace fossils that occur in the Upper Triassic Chinle and Dolores Formations on the Colorado Plateau are interpreted to be the casts of lungfish burrows. The casts, which are as much as 11 cm in diameter and as much as 1.6 m long, were formed by passive siliciclastic and carbonate sedimentation into apparently abandoned lungfish burrows. Locally, the burrow fillings are overwhelmingly abundant, and many intersect and have destroyed former burrow fillings. Superposition of bioturbation episodes has obliterated most primary sedimentary structures. This bioturbation has contributed to the mottled coloration and the knobby-weathering texture of the rocks. The …

Patterns Of Dental Evolution In Early Eocene Anaptomorphine Primates (Omomyidae) From The Bighorn Basin, Wyoming, Thomas M. Bown, Kenneth D. Rose

United States Geological Survey: Staff Publications

ABSTRACT--The subfamily Anaptomorphinae contains the oldest and most generalized members of the tarsier-like primates and is the basal group of the extinct family Omomyidae. The best and most continuous record of anaptomorphine history is from rocks of early Eocene (Wasatchian) age in the Bighorn Basin of northwest Wyoming where eight genera and 14 species are recognized. Three of these species are new (Teilhardina crassidens, Tetonius matthewi, Absarokius metoecus), and four other new species are described from elsewhere (Tetonius mckennai, Absarokius gazini, A. australis, Strigorhysis huerfanensis). Teilhardina tenuicula and Absarokius nocerai are …

Sedimentology Of The Upper Triassic Chinle Formation Southeastern Utah: Paleoclimatic Implications, Russell F. Dubiel

United States Geological Survey: Staff Publications

The Upper Triassic Chinle Formation in southeastern Utah was deposited in a complex fluvial-deltaic-lacustrine system. The Chinle records the evolution of a continental system in response to variations in climate, tectonics, and sediment supply. Chinle strata represent deposits of fluvial channels and floodplains, lacustrine deltas, lacustrine basins, and lacustrine and playa mudflats. These rocks include a variety of vertebrate, invertebrate, and plant fossils, trace fossils, and paleosols that provide information on depositional environments, water tables, and paleoclimate.

Sedimentologic and paleontologic interpretations both support an interpretation of abundant lakes, streams, and marshes with high, but fluctuating water tables for all but …

Cliff-Height And Slope-Angle Relationships In A Chronosequence Of Quaternary Marine Terraces, San Clemente Island, California, Russell Crittenden, Daniel R. Muhs

United States Geological Survey: Staff Publications

Zusammenfassung. Eine Abfolge quartarer Strandterrassen auf ~an Clemente Island, Kalifornien, liefert einen Rahmen fur die quantitative Analyse der Anderungen an vom Meer verlassenen Kustenkliffen als Funktion der Zeit. Es wurde eine Abschatzung der Anwendbarkeit von BUCKNAM & ANDERSON (1979) log-lin~arer Beziehung zwischen Wandhohe und Hangwinkel durchgefuhrt, indem Brandungskliffhohe und maximale Hangwinkel verwendet wurden. Die Ergebnisse zeigen eine regelhafte Zunahme des Hangwinkels mit dem Logarithmus der Kliffhohe, und Kliffe einer bestimmten Hohe zeigen m,it der Zeit eine Abnahmedes maximalen Hangwinkels. 1m ganzen waren die Relationen schwacher als fur FluBterrassen und Bruchstufen in unverfestigten Materialen, aber die Methode kann wahrscheinlich verwendet werden, …

Moving Under, Around, And Through The Miocene Reconstruction Of Southern California, John Barron

United States Geological Survey: Staff Publications

Modern southern California is fragmented by faults that juxtapose blocks with contrasting topographies and differing geologic histories. Many of the tectonic events that have shaped southern California were initiated during the Miocene, as subduction along the ancient trench margin off southern California was replaced by transform (strikeslip) faulting, such as that along the San Andreas fault.

Paleoclimates In Southwestern Tasmania During The Last 13,000 Years, Vera Markgraf, J. Platt Bradbury, J.R. Busby

United States Geological Survey: Staff Publications

Plant-sociological and climatic classification of the Australian Nothofagus cunninghamii rain forest provides the basis for a new, semiquantitative approach to interpretations of late-Quaternary paleoclimates from four pollen sequences in southwestern Tasmania. Varying proportions of rain-forest pollen types in the records were related to different modern rain-forest alliances and their specifc climatic regimes, such as Eastern Rain Forest, Leatherwood Rain Forest, and sclerophyllous, Subalpine Rain Forest. According to this interpretation, early Holocene climates were characterized by 1,600 mm annual precipitation and 10°C annual temperature, conditions substantially warmer and drier than previously thought. Maximum precipitation levels of 2,500 mm annually were not …

Late Pleistocene And Holocene Paleolimnology Of Two Mountain Lakes In Western Tasmania, J. Platt Bradbury

United States Geological Survey: Staff Publications

The analysis of diatoms from two lake-sediment cores from southwestern Tasmania that span the Pleistocene-Holocene boundary provides insight about paleolimnological and paleoclimatic change in this region. Both Lake Vera (550 m elevation), in west-central Tasmania, and Eagle Tarn (1,033 m elevation), in south-central Tasmania, have lacustrine records that begin about 12,000 years ago. Despite significant differences in location, elevation, and geologic terrane, both lakes have, had similar, as well as synchronous, limnological histories. Each appears to have been larger and more alkaline 12,000 years ago than at present, and both became shallower through time. Fossil diatom assemblages about 11,500 years …

Diatom Stratigraphy Of The Lower Pliocene Part Of The Sisquoc Formation, Harris Grade Section, California, John A. Barron, Jack G. Baldau

United States Geological Survey: Staff Publications

Lower Pliocene diatoms were studied from the Sisquoc Formation and lowermost Foxen Mudstone, exposed along Hams Grade north of Lompoc, California, to refine the diatom biostratigraphy of post-Monterey Formation sediments in California. Sixty-seven diatom taxa were identified in the 25 samples examined from the 790-m thick (2950-ft) section. The diatoms are assignable to the uppermost Nitzschia reinholdii Zone and Thalassiosira oestrupii Zone of Damn (1981), and five tentative subzones for local correlation are proposed. Regional correlations and taxon occurrence are discussed, and the base of the Nitzschia reinholdii Zone is redefined as at the last occurrence of Thalassionema schraderi.

Age Of The Earliest African Anthropoids, John G. Fleagle, Thomas M. Bown, John D. Obradovich, Elwyn L. Simons

United States Geological Survey: Staff Publications

The earliest fossil record of African anthropoid prunates (monkeys and apes) comes from the Jebel Qatrani Formation in the Fayum depression of Egypt. Reevaluation of both geologic and faunal evidence indicates that this formation was deposited in the early part of the Oligocene Epoch, more than 31 million years ago, earlier than previous estimates. The great antiquity of the fossil higher prunates from Egypt accords well with their primitive morphology compared with later Old World higher prunates. Thus, the anthropoid primates and hystricomorph rodents from Fayum are also considerably older than the earliest higher primates and rodents from South America.

Thalassiosira Praeoestrupii- A New Diatom Species For Recognizing The Miocene/Pliocene Epoch Boundary In Coastal California, Michael P. Dumont, Jack G. Baldauf, John A. Barron

United States Geological Survey: Staff Publications

A new diatom species, Thalassiosira praeoestrupii Dumont, Baldauf and Barron, is described. The first occurrence of T. praeoestrupii in coastal California diatom-bearing outcrops occurs between the last occurrence of Rouxia californica at 6.0 Ma, and the first occurrence of Thalassiosira oestrupii at 5.1 Ma. The latter two species have customarily been used to identify the Miocene/Pliocene boundary. Paleomagnetic studies at Santa Cruz, California, demonstrate that the first occurrence of T. praeoestrupii coincides with the top of magnetic polarity Chron 5, which closely approximates the Miocene/Pliocene Epoch boundary.

Reconnaissance Bathymetry Of Basins Occupied By Pleistocene Lake Lahontan, Nevada And California, Larry Benson, M. D. Mifflin

United States Geological Survey: Staff Publications

Beginning about 12,500 years B.P., Lake Lahontan began to decline (fig. 1: Black Rock Desert data from Davis [1983]; Truckee River Delta data from Born [1972]; tufa data from Benson [1981]; packrat-midden data from Thompson and others [1985]) . As water levels declined, their altitudes fell below sill altitudes (table 1); locations of these sills are shown in figure 2. Today, five surface-water bodies (Black Rock Playa, Humboldt-Carson Sink, Walker Lake, Pyramid Lake, Honey Lake) exist in four of the seven subbasins (fig. 2).

The collective surface area of the modern lakes today (1985) totals less than 1,600 km2 . …