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Articles 27601 - 27630 of 29717
Full-Text Articles in Physical Sciences and Mathematics
Molluscan Paleontology Of The Pliocene Peace Valley "Beds" And Ridge Route "Formation" (Ridge Basin Group), Ridge Basin, Southern California, Daniel R. Young
Molluscan Paleontology Of The Pliocene Peace Valley "Beds" And Ridge Route "Formation" (Ridge Basin Group), Ridge Basin, Southern California, Daniel R. Young
Theses and Dissertations
The Ridge Basin, 90 km northwest of Los Angeles, California, lies within the San Gabriel, San Andreas, Liebre, and Clearwater fault zones. The basin is an elongated, wedge-shaped, intermontane, Miocene-Pliocene basin filled with about 12 000 m of marine, lacustrine, fluvial, and alluvial sediment. More than half of the thickness of the Ridge Route "formation" and about one fifth of the Peace Valley "beds" was examined for molluscs along the northeastern side of the basin and more than 600 m of section were measured.
The nonmarine molluscs of the Ridge Route "formation" and Peace Valley "beds" consist of ten species: …
Periglacial Landforms And Processes In The Southern Kenai Mountains, Alaska, Palmer K. Bailey
Periglacial Landforms And Processes In The Southern Kenai Mountains, Alaska, Palmer K. Bailey
Theses and Dissertations
The distribution and characteristics of periglacial landforms in the southern Kenai Mountains, Alaska, were investigated during the summer of 1979. The principal area of study was a 1300-metre high mountain mass which stood as a nunatak during the last general glaciation. Periglacial features in the area include gelifluction lobes, nivation hollows, cryoplanation terraces, tors, a string bog, and various for111S of patterned ground such as sorted circles, sorted polygons, earth hummocks, sorted steps, sorted stripes, and small ice-wedge polygons.
Ground temperature measurements indicate that permafrost recently existed in the area but is no longer present. The sorted polygons, cryoplsnation terraces, …
Provenance Study Of The Westwater Canyon And Brushy Basin Members Of The Morrison Formation Between Gallup And Laguna, New Mexico, Ruben Martinez
Provenance Study Of The Westwater Canyon And Brushy Basin Members Of The Morrison Formation Between Gallup And Laguna, New Mexico, Ruben Martinez
Earth and Planetary Sciences ETDs
The objective of this investigation is to study the provenance of the Westwater Canyon and Brushy Basin Members of the Morrison Formation between Gallup and Laguna, New Mexico. The coarse, subarkosic Westwater Canyon Member is separated from the quartzitic sandstones of the underlying Recapture Member by an unconformity that provides a recognizable datum for correlation and a definite base for the Westwater Canyon Member.
The very pale orange, cliff-forming Westwater Canyon Member consists of Oto 137 m of very coarse- to very fine-grained, poorly sorted, subrounded to angular, arkosic to quartzitic sandstone with numerous lenses of arkosic granules and pebbles …
Petrogenesis Of Orbicular Rock, Tijeras Canyon, Sandia Mountains, New Mexico, Kathleen Affholter
Petrogenesis Of Orbicular Rock, Tijeras Canyon, Sandia Mountains, New Mexico, Kathleen Affholter
Earth and Planetary Sciences ETDs
A new occurrence of orbicular rock is located in the Sandia Granite at W. long. 106° 25' 30", N. lat. 35° 04' 55" close to the granite-gneiss contact near Tijeras Canyon, Sandia Mountains, New Mexico. The orbicules, set in an aplite-pegmatite granitic matrix, have magmatic and metamorphic cores surrounded by a white plagioclase shell and one or two salmon-colored potassium feldspar shells. The outcrop occurs in two dike-like masses with thicknesses of 1 to 4 m trending N. 5° W. and N. 35° E. for exposed lengths of 16m and 46 m, and is surrounded by biotite syenodiorite and biotite …
Geology Newsletter- 1979, Department Of Geology
Geology Newsletter- 1979, Department Of Geology
Geological and Environmental Sciences News
Includes a list of short news items from the chair, Lloyd Schmaltz, addressed to alumni and friends.
Geology Of The Cerro Del Grant Area, Rio Arriba County, North-Central New Mexico, John Richmond Lawrence
Geology Of The Cerro Del Grant Area, Rio Arriba County, North-Central New Mexico, John Richmond Lawrence
Earth and Planetary Sciences ETDs
The present study undertook the geologic mapping and investigation of the stratigraphy, structural geology, igneous petrology and mineral resources of the Cerro del Grant area, a 75- (190 ) region near Coyote, Rio Arriba County, north-central New Mexico. The area is situated at the junction of three geologic provinces: the Chama platform, the Española Basin of the Rio Grande rift, and Jemez volcanic field.
Sedimentary rocks include 2,500 ft (830 m) of sandstone, shale, conglomerate and limestone of Late Triassic to Quaternary age. These strata are unconformably overlain by several hundred feet of mafic, intermediate and rhyolitic lavas which make …
Structural And Petrologic Comparison Of The Southern Sapphire Range, Montana With The Northeast Border Zone Of The Idaho Batholith, Stacy Lon Clark
Structural And Petrologic Comparison Of The Southern Sapphire Range, Montana With The Northeast Border Zone Of The Idaho Batholith, Stacy Lon Clark
Masters Theses
No abstract provided.
Analysis And Interpretation Of The 5,000 Ft (1,538 M) Red-Bed Sequence Encountered In The Sparks Et Al. #1-8 (Michigan Basin Deep Borehole), John H. Fowler
Analysis And Interpretation Of The 5,000 Ft (1,538 M) Red-Bed Sequence Encountered In The Sparks Et Al. #1-8 (Michigan Basin Deep Borehole), John H. Fowler
Masters Theses
A 5,000 ft (1,538 m) pre-Mt. Simon (Upper Cambrian) red-bed sequence, encountered in the Gratiot County deep borehole (Sparks et al. #1-8) and herein named the North Star Formation, consists of undeformed recurring beds of immature arkosic sandstone 2 to 34 in (5 to 85 cm) thick. These beds grade upward from erosional basal contacts into mudstone units 1 in to 12 ft (3 cm to 3.8 m) thick. Within the sandstones, grading, horizontal lamination, and crossstratification define Bouma intervals "a", "b", and "c", which combine to form incomplete Bouma sequences. Mudstones exhibit abundant horizontal laminations. Secondary sedimentary structures (load …
Atmospheric Implications Of Studies Of Central American Volcanic Eruption Clouds, R. D. Cadle, A. L. Lazrus, B. J. Huebert, L. E. Heidt, William I. Rose, D. C. Woods, Raymond L. Chuan, Richard E. Stoiber, D. B. Smith, Robert A. Zielinski
Atmospheric Implications Of Studies Of Central American Volcanic Eruption Clouds, R. D. Cadle, A. L. Lazrus, B. J. Huebert, L. E. Heidt, William I. Rose, D. C. Woods, Raymond L. Chuan, Richard E. Stoiber, D. B. Smith, Robert A. Zielinski
Department of Geological and Mining Engineering and Sciences Publications
During February 1978 a group of scientists from the National Center for Atmospheric Research, several colleges and universities, the U.S. Geological Survey, and NASA used a specially equipped Beech Queen Air aircraft to make 11 sampling flights in Guatemala through the eruption clouds from the volcanoes Pacaya, Fuego, and Santiguito. Measurements were made of SO42−, SO2, HCl, HF, and 11 cations that were in water-soluble form, on samples collected by a specially designed filter pack. Particle size distributions were obtained with a piezoelectric cascade impactor, and the particles were identified by energy dispersive X ray …
The Origin Of Fine Scale Acoustic Stratigraphy In Deep-Sea Carbonates, Larry A. Mayer
The Origin Of Fine Scale Acoustic Stratigraphy In Deep-Sea Carbonates, Larry A. Mayer
Affiliate Scholarship
In this paper we investigate the origin and geologic significance of the closely spaced high-frequency subbottom acoustic reflectors characteristic of pelagic carbonates. A detailed survey was conducted of a small area in the equatorial Pacific with the Marine Physical Laboratory's Deep-Tow instrument package, providing high-resolution 4-kHz profiles and precise positioning of core samples. The cores were sampled at closely spaced intervals for sound velocity and saturated bulk density. Acoustic impedances were calculated, and a reflection coefficient log determined for the upper 10 m of the sediment column. The reflection coefficient log revealed no interfaces with large reflection coefficients that correlated …
Rubidium-Strontium And Related Studies Of The Salado Formation, Southeastern New Mexico, Joseph K. Register Jr.
Rubidium-Strontium And Related Studies Of The Salado Formation, Southeastern New Mexico, Joseph K. Register Jr.
Earth and Planetary Sciences ETDs
The Salado Formation, a member of the Ochoa Series, is a bedded salt deposit which is found in the Delaware Basin southeastern New Mexico and west Texas. It is comprised primarily of halite and sylvite with minor amounts of sulfate minerals. Rubidium-strontium age determinations of the evaporite minerals in the Salado indicate an age of final equilibration of 214 15 m.y. This age is fairly consistent with the geologic age of the formation, precluding substantial alkali-alkaline earth migration since deposition. Polyhalite and anhydrite samples from the Salado give / values of about .7078, which are consistent with reported valued for …
Oxygen Isotopic Analysis Of Silicates And Oxides Using Both Bromine Pentafluoride And Fluorine Gas As Reagents, Harold Roy Northrop
Oxygen Isotopic Analysis Of Silicates And Oxides Using Both Bromine Pentafluoride And Fluorine Gas As Reagents, Harold Roy Northrop
Earth and Planetary Sciences ETDs
In recent years the preferred analytical procedure for the extraction of oxygen from silicates and oxides for oxygen isotope analysis has been the oxidation of the samples with either fluorine (F2) or bromine pentafluoride (BrF5) to produce oxygen. Several standards are available for monitoring the extraction procedure, and one in particular (NBS-28) is used in many laboratories. The oxygen-18 oxygen-16 ratios obtained for NBS-28 vary by as much as one permil between laboratories. The major cause of this variation lies in the extraction procedure used. Extraction of oxygen from iron bearing minerals and whole rocks (and minerals containing certain other …
The Geology And Geochemistry Of The North Fork Stock, Northeastern Oregon, David Joseph Matty
The Geology And Geochemistry Of The North Fork Stock, Northeastern Oregon, David Joseph Matty
Dissertations and Theses
The North Fork stock is a composite intrusive body of Late Jurassic-Early Cretaceous age which outcrops in the Blue Mountains of northeastern Oregon. The upper 600 m of the intrusion are exposed over an area of approximately 36 km2 along the canyon walls of the North Fork of the John Day River in Grant and Umatilla counties. The stock intrudes metasediments, metavolcanics, and metagabbros associated with the Permian-Triassic Elkhorn Ridge Argillite. Contact metamorphism of the Elkhorn Ridge Argillite is developed to the hornblende-hornfels facies throughout most of the exposed area of this unit in the study area. The contact …
Broadwater Ne Quadrangle, Morrill County, Nebraska, Robert F. Diffendal Jr.
Broadwater Ne Quadrangle, Morrill County, Nebraska, Robert F. Diffendal Jr.
Robert F. Diffendal, Jr., Publications
7.5' topgraphic quadrangle showing exposures of bedrock formations and other geologic information.
41° 37'30" — 41° 45'
102° 45' — 102° 52'30"
Scale 1:24,000
Completed June 6, 1979
High resolution .tif file attached below as supplemental file
Geology Of The Galisteo Formation, Hagan Basin, New Mexico, Timothy Walker Gorham
Geology Of The Galisteo Formation, Hagan Basin, New Mexico, Timothy Walker Gorham
Earth and Planetary Sciences ETDs
In north-central New Mexico the Hagan basin contains the thickest (261 to 1,295 m) and least deformed section of the Eocene Galisteo Formation. The Galisteo unconformably overlies sandstone and carbonaceous shale of the Mesaverde Group (Upper Cretaceous) and provides a record of late Laramide (Eocene) tectonics in this part of the Rocky Mountains.
The Galisteo Formation contains a complex fluvial sequence of abundant red to green mudstone, with varying amounts of red to white laterally continuous and discontinuous sandstone, and buff to white conglomeratic sandstone. Sedimentary structures and facies relationships in seven coarse-grained Galisteo members indicate that the Galisteo Formation …
The Matrix Of Unequilibrated Ordinary Chondrites: Implications For The Origin And Subsequent History Of Chondrites, Gary Robert Huss
The Matrix Of Unequilibrated Ordinary Chondrites: Implications For The Origin And Subsequent History Of Chondrites, Gary Robert Huss
Earth and Planetary Sciences ETDs
The matrices of fourteen unequilibrated (type 3 and 3, 4) ordinary chondrites (all witnessed falls) were analyzed using transmitted and reflected light microscopy, electron microprobe analysis, and instrumental neutron activation analysis. The matrix is defined as the fine-grained silicate material between chondrules, chondrule fragments, other distinct silicate grains, and Fe-Ni and troilite grains. It makes up about 13 percent of each meteorite. Although all meteorites in this study have been altered to some extent since their formation, those with least alteration indicate that the unaltered matrix had submicron grain size, a clastic texture, and was friable even though interstitial pore …
Structural Geology Of The Northern Part Of Oxford Quadrangle, Idaho, Jerrold N. Mayer
Structural Geology Of The Northern Part Of Oxford Quadrangle, Idaho, Jerrold N. Mayer
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
The northern part of the Oxford Quadrangle, Idaho, includes parts of the Bannock Range to the west and the Portneuf Range to the east. These ranges are separated by Marsh Valley to the north and Cache Valley to the south. Red Rock Pass, the outlet of glacial Lake Bonneville, divides the two valleys. The mapped area is north of Preston, Idaho, and south of Downey, Idaho. The north-south dimension of the mapped area is 5.2 miles and the east-west dimension is 6.4 miles.
The stratigraphic units, within the mapped area, are Precambrian, Paleozoic, and Cenozic in age. The oldest rock …
The Geology And Blueschist Petrology Of The Western Ambler Schist Belt, Southwestern Brooks Range, Alaska, Craig Joseph Nelsen
The Geology And Blueschist Petrology Of The Western Ambler Schist Belt, Southwestern Brooks Range, Alaska, Craig Joseph Nelsen
Earth and Planetary Sciences ETDs
The western Ambler Schist Belt is located in the southern Brooks Range of Alaska and is defined in this study as that part of the Brooks Range schist belt which contains abundant bimodal volcanic, volcaniclastic and related carbonate sediments. The schist belt appears to be the basinal part of Middle Devonian through Mississippian shelf-slope-basin sequence. To the south of the schist belt are upper Paleozoic-Mesozoic (?) ophiolite overlain by Cretaceous greywackes and calc-alkalic intrusives and related extrusives. These two distinct terrains are juxtaposed along a suspected continental suture, the Angayucham-Cosmos Hills-Jade Mountain belt, on with a minimum of 115 km …
Petrology And Mineralogy Of Quaternary Basalts, Gem Valley And Adjacent Bear River Range, Southeastern Idaho, William D. Perkins
Petrology And Mineralogy Of Quaternary Basalts, Gem Valley And Adjacent Bear River Range, Southeastern Idaho, William D. Perkins
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Quaternary basalts of Gem Valley, Idaho, are present as valley fill (Group 1) and as well defined flows in the Bear River Range (Group 2) east of Gem Valley. Minerals present in both groups of basalts include olivine (Fo73 -Fo39), augite (Wo41 En39 Fs20), plagioclase (An75 -An40), and Fe-Ti oxides. Coexisting pairs of magnetite and ilmenite, and olivine and clinopyroxene in several samples indicate temperatures of crystallization from 958°c to 1167°c. The Group 2 basalts exhibit a cumulate texture with abundant large (2 cm) phenocrysts of plagioclase.
Chemically, the Gem …
Structural Geology Of Eastern Part Of James Peak Quadrangle And Western Part Of Sharp Mountain Quadrangle, Utah, Steven L. Rauzi
Structural Geology Of Eastern Part Of James Peak Quadrangle And Western Part Of Sharp Mountain Quadrangle, Utah, Steven L. Rauzi
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
A detailed study was made of the James Peak-Sharp Mountain area, in the southern part of the Bear River Range, Utah. The mapped area is located in north-central Utah between lat. 41°22'30" N. and lat. 41°30' N. and long. 111°42'30" W. and long. 111°46' W. It measures about 3.8 miles in the east-west direction and 8.7 miles in the north-south direction. The area is centered about 22 miles south-southeast of Logan, Utah.
Stratigraphic units of late Precambrian to Mississippian age underlie the mapped area. The Precambrian units include the Mutual and Browns Hole Formations. The Brigham, Langston, Ute, Blacksmith, Bloomington, …
Interpretive Study And Numerical Model Of The Hydrogeology Upper Big Blue Natural Resources District., Ralph E. Cady, Marilyn H. Ginsberg
Interpretive Study And Numerical Model Of The Hydrogeology Upper Big Blue Natural Resources District., Ralph E. Cady, Marilyn H. Ginsberg
Conservation and Survey Division
No abstract provided.
Geology Of The Central Peloncillo Mountains, The North Third Of The Pratt Quadrangle, Hidalgo County, New Mexico, Dennis J. Gebben
Geology Of The Central Peloncillo Mountains, The North Third Of The Pratt Quadrangle, Hidalgo County, New Mexico, Dennis J. Gebben
Masters Theses
No abstract provided.
Postglacial Environmental History Of A Marl Lake Site In Kalamazoo County, Southwestern Michigan, Valerie A. Naeve
Postglacial Environmental History Of A Marl Lake Site In Kalamazoo County, Southwestern Michigan, Valerie A. Naeve
Masters Theses
The depositional and ecological history of Oakland Bog, a relic Wisconsinan (16,500+300 years B.P.) lake site is interpreted from pollen stratigraphy, molluscan faunal assemblages and sediment facies. The lake basin, which probably formed after the melting of a late Wisconsinan buried ice block in the Kalamazoo Moraine Complex, is irregular, steep-sided and floored by glacial till. The till is overlain by as much as 7.6 meters of lacustrine marls which extend over an area of nearly 0.5 km2. Basal marls are characteristically medium gray, clayey, and contain abundant calcified stem fragments of charophytes; however, the overlying marls display …
Tree Root Systems In Eastern Nebraska, John A. Sprackling, Ralph A. Read
Tree Root Systems In Eastern Nebraska, John A. Sprackling, Ralph A. Read
Conservation and Survey Division
No abstract provided.
Geologic History Of Scotts Bluff National Monument, Roger K. Pabian, James B. Swinehart Iii
Geologic History Of Scotts Bluff National Monument, Roger K. Pabian, James B. Swinehart Iii
Conservation and Survey Division
No abstract provided.
Petrography, Mineral Chemistry And Microstructures Of Gabbros From The Mid-Cayman Rise Spreading Center, Frieda L. Malcolm
Petrography, Mineral Chemistry And Microstructures Of Gabbros From The Mid-Cayman Rise Spreading Center, Frieda L. Malcolm
Geology Theses and Dissertations
The suite of gabbroic rocks collected by the DSRV ALVIN in 1976 and 1977 from the walls of the Mid-Cayman Rise spreading center were studied in detail to provide the best available data on plutonic rocks sampled directly from the ocean floor. The rock types studied include variably deformed and altered gabbros, orthopyroxene gabbros, olivine gabbros and troctolites, and a few amphibolites. Mineral chemical analyses suggest that the various rock types are representative of a fractionation trend from magnesian troctolites through olivine and clinopyroxene gabbros to iron-enriched orthopyroxene gabbros. Within many individual samples, the primary mineral phases are apparently chemically …
Geology Of The Mafic/Ultramafic Transition, Table Mountain, Western Newfoundland, Suzanne O'Connell
Geology Of The Mafic/Ultramafic Transition, Table Mountain, Western Newfoundland, Suzanne O'Connell
Geology Theses and Dissertations
A thin (<200 m.) mafic suite and well developed mafic/ultramafic transition zone are exposed above a flat lying peridotite contact on northwestern Table Mountain. The igneous layering and sedimentary features indicate mineral deposition under conditions which promoted adcumulate growth, were capable of minor transport, and were subjected to at least minor tectonic activity during consolidation. Feldspathic,. mafic, and ultramafic dikes and veins cross-cut the layering. Microscopic futures indicate deformation at elevated temperature and/or low strain rates. Deformation is best developed within the transition zone, but cataclastic zones are most common in the hornblende gabbros. Orientations of layering, foliation, and lineation indicate a variable mafic/ultramafic transition and macroscopic folding. Geometric analysis indicates three distinct fold axis orientations: an east-west horizontal fold axis, a northeast trending modestly plunging axis, and a vertical though poorly defined axis. Such features demonstrate that an apparently simple contact relationship may be extremely complex. This has important implications for ocean floor accretion. The relatively simple ocean floor seismic stratigraphy masks very complex petrological and structural processes. Such processes may involve deposition in an actively convecting magma chamber with a differentially subsiding wedge (Dewey and Kidd, 1977), in which folding occurs in response to the steepening angle between the cumulate banding and the base of the magma chamber. The instability is enhanced by the different accumulation rates and densities of the minerals involved. The lineation may originally be a sedimentary feature indicative of transport direction from the convection cell, and perpendicular to the compressive stress which produced. the folding. The different orientations of lineations and fold axes could be produced by rotation of the ocean crustal blocks during lateral transport along the ocean floor and/or obduction. Further detailed study of ophiolite complexes will continue to shed light upon the nature and development of oceanic crust.
Paleoclimatic Implications Of Oxygen Isotope And Sedimentological Study Of Late Miocene And Early Pliocene Sediments From The South Atlantic, Western Indian Ocean, And The Gulf Of Aden, Kathryn M. Scanlon
Geology Theses and Dissertations
Previous work by many authors has implied that the Antarctic ice sheet underwent a major expansion in the latest Miocene. It was intended in the present study to use the oxygen isotope event, which could be expected to accompany this glacial expansion, as a stratigraphic marker to aid in the correlation of several DSDP Sites. Samples were taken at approximately 100,000 year intervals throughout the latest Miocene and early Pliocene sections at Sites 237 and 249 in the western Indian Ocean, Site 360 in the South Atlantic and Site 231 in the Gulf of Aden. Oxygen isotope analyses were done …
Geometry And Kinematics Of Continental Deformation In Zones Of Collision: Examples From Central Europe And Eastern Mediterranean, Ali Mehmet Celâl Sengör
Geometry And Kinematics Of Continental Deformation In Zones Of Collision: Examples From Central Europe And Eastern Mediterranean, Ali Mehmet Celâl Sengör
Geology Theses and Dissertations
Consideration of world-wide epicenter distribution has shown that deformation in continental lithosphere is not narrowly confined to well-defined plate boundaries but is present in wide, diffuse plate boundary zones. Early studies on the seismicity of the peri-Mediterranean area resulted in the division of the lithosphere in that region into a number of small plates, or microplates. Later studies in central Asia, which integrated seismicity with Quaternary geology, indicated, however, that a continuum approach may be more realistic to describe continental tectonics. This study concentrates on geometry and timing of continental deformation that resulted from continental collision in Central Europe and …
Petrology And Mineral Chemistry Of Some Jan Mayen Volcanics, Carla A. White
Petrology And Mineral Chemistry Of Some Jan Mayen Volcanics, Carla A. White
Geology Theses and Dissertations
The island of Jan Mayen is the northernmost active volcano on the Mid-Atlantic Ridge. The rocks of Jan Mayen belong to the potassic series of the alkaline rocks and appear to belong to the straddle type association. The ankaramites and alkali olivine basalts are characterized by the presence of large xenocrysts of rimmed chromium diopside, titaniferous salite, olivine (Fo83 to Fo88), magnetite and sometimes plagioclase (bytownite rimmed by labradorite). Phenocrysts of olivine (Fo74) and plagioclase (andesine) are present in several rocks. These and phenocrysts lie in a matrix composed of` titaniferous salite, olivine (Fo58), plagioclase (andesine), magnetite, biotite and sometimes …