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Articles 27631 - 27660 of 29955

Full-Text Articles in Geology

Seismic Modelling And Paleoceanography At Dsdp Site 574, Larry A. Mayer, Tom H. Shipley, Fritz Theyer, Roy H. Wilkens, Edward L. Winterer Oct 1985

Seismic Modelling And Paleoceanography At Dsdp Site 574, Larry A. Mayer, Tom H. Shipley, Fritz Theyer, Roy H. Wilkens, Edward L. Winterer

Affiliate Scholarship

The analysis of high-resolution watergun seismic profiles collected in support of DSDP Leg 85 drilling reveals sev eral major, regionally traceable reflectors that can be correlated over more than 360,000 km2 in the central equatorial Pacific. Synthetic seismograms generated from shipboard physical property measurements (carefully corrected to in situ values) for DSDP Site 574 show excellent agreement with the field records; the agreement suggests that the traveltime to-depth conversion is accurate and permits the precise (± 5 m) location of reflectors in the cored section. The reflectors can be dated (±0.5 Ma) as follows: Orange, 21.5 to 22.5 Ma; Yellow, …


Depositional Environments Of Late Precambrian Sediments From Liberia, Sierra Leone, And Senegal, West Africa, Alfred W. Magee Iii Oct 1985

Depositional Environments Of Late Precambrian Sediments From Liberia, Sierra Leone, And Senegal, West Africa, Alfred W. Magee Iii

OES Theses and Dissertations

Field and hand sample descriptions were supplemented with petrographic and textural analyses derived from thin sections, and scanning electron microscopy (SEM) to determine environments of deposition for the late Precambrian Gibi Mountain Formation, Liberia, Tabe

Formation, Sierra Leone, and the basal Mali Group, Senegal, West Africa.

The Gibi Mountain Formation consists of a glaciomarine tillite, marine laminites with dropgrains, and shallow water arkoses. A shale facies remains unresolved in origin.

The Tabe Formation is composed of three members: Tibai, Dodo, and Taban. The Tibai Member contains a glaciomarine tillite deposited in a shallow shelf marine environment, marine laminites, and shallow …


Lineament Analysis And Tectonic Interpretation For The Central Tharsis Region, Mars, Robert C. Anderson Oct 1985

Lineament Analysis And Tectonic Interpretation For The Central Tharsis Region, Mars, Robert C. Anderson

OES Theses and Dissertations

Lineament studies conducted for the Central Tharsis Region of Mars (JOON and JOOS latitude; 450w to 157.50W longitude) indicate two major events controlled the formation of the Tharsis Dome: 1) a pre-Tharsis fracture system consisting of North-West (3150) trending fractures; and 2) a Tharsian fracture system containing North-South (355°) and East-West (275°) trending fractures. The North-West (3150) trending fractures represent a crustal weakness zone which controlled the early formation of the Tharsis Dome. Analytical studies suggest four centers of uplift: 1) 6°N, 124°W; 2) 0.5°N, 114°W; 3) 5°S, 105°W; and 4) 7°S, 104°W. Each of these uplifting centers is associated …


Leachate Monitoring In Naturally Saline Groundwater Chesapeake Landfill Chesapeake Virginia, T. Britt Mcmillan Oct 1985

Leachate Monitoring In Naturally Saline Groundwater Chesapeake Landfill Chesapeake Virginia, T. Britt Mcmillan

OES Theses and Dissertations

Groundwater chemistry around the Chesapeake municipal landfill was monitored over a one year period. Ten sample sites as well as two surface water sites were used to monitor water quality. Two wells, one at 3 m and the other at 10 m were located at each site. Surface water samples were taken from the Elizabeth River, north of the landfill, and a tidal channel, west of the landfill. Seven groundwater sites were downgradient of the landfill and three sites were upgradient (control sites).

The landfill overlies a tidal marsh, approximately 100 m south of the intracoastal waterway (Elizabeth River). Dredge …


Conodont Biostratigraphy Of The Cambrian-Ordovician Boundary Interval In The Northern Shenandoah Valley Of Virginia, U.S.A., Randall C. Orndorff Oct 1985

Conodont Biostratigraphy Of The Cambrian-Ordovician Boundary Interval In The Northern Shenandoah Valley Of Virginia, U.S.A., Randall C. Orndorff

OES Theses and Dissertations

Conodonts collected from two measured sections in the northern Shenandoah Valley of Virginia indicate that locally the Cambrian-Ordovician boundary is within the upper part of the Conococheague Formation and that the Conococheague-Stonehenge formational contact as defined in this study, is diachronous in relation to the boundary. Using the generally accepted definition of the CambrianOrdovician boundary as at the base of the trilobite Missisguoia Zone or within the conodont Hirsutodontus hirsutus Subzone of the Cordylodus proavus Zone, it is found here that the boundary is 230 ft (70 m) below the formational contact at the Narrow Passage Creek section. Several North …


Depositional Model For The Auriferous Gravels In The Payan Mining District Department Of Narino, Columbia, South America, Jim R. Garrett Oct 1985

Depositional Model For The Auriferous Gravels In The Payan Mining District Department Of Narino, Columbia, South America, Jim R. Garrett

OES Theses and Dissertations

Unlike placer deposits in arid and semi-arid environments where gold concentration is closely tied to the position of the bedrock, Payan placer deposits have no association with bedrock. Gold concentration values show highest gold concentrations occur at the contact of a coarse sand unit and its underlying gravel unit. Comparisons of the size and shape distributions of gold grain populations with their associated black sand populations indicate the gold and black sand were not deposited in hydraulic equilibrium. The mean size of each gold population is consistently coarser than the mean size of its associated black sand population despite the …


A Gravity Investigation Of Mountain Flank Thrusting And Normal Faulting, Madison And Tobacco Root Ranges, Montana, Stephen Thomas Wigger Aug 1985

A Gravity Investigation Of Mountain Flank Thrusting And Normal Faulting, Madison And Tobacco Root Ranges, Montana, Stephen Thomas Wigger

Masters Theses

Gravity modeling of west-dipping, Laramide mountain flank thrusts which involve Archean metamorphic rocks in the western Tobacco Root and northern Madison Ranges supports the idea that these thrusts are gently dipping.

The thrusts provided a favorable location for normal faulting during Neogene extension. The Neogene faults on the eastern portions of the Madison and Jefferson Basins are interpreted to be listric, and merge with the Laramide thrusts. Basin development occurred along a series of such faults, which dropped hanging wall blocks of the thrust sheets to progressively greater depths. The maximum depth of the Madison basin, near Ennis, was found …


A Seismic Study Of An Impact Feature In Cass County, Michigan, Mancheol Suh Aug 1985

A Seismic Study Of An Impact Feature In Cass County, Michigan, Mancheol Suh

Masters Theses

A geophysical investigation, including a seismic study, of the subsurface structure of the Calvin-28 oil field, Cass County, Michigan, indicates that the structure's origin may be related to an impact event. The structural closures in the time structure maps and drilling results both show a central uplift. The fault system in the Trempealeau Formation shows a structure similar to other proven astroblemes. Undisturbed layers just beneath the central uplift also provide evidence of an impact structure. The result of mathematical modeling of the central uplift under the assumption that the structure is an impact structure corresponds well with the drilling …


The Amphibians And Reptiles Of Nebraska, George E. Hudson Aug 1985

The Amphibians And Reptiles Of Nebraska, George E. Hudson

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Subsurface Stratigrapy And Sedimentologic Control On The Productive Middle Devonian Age Richfield Member Of The Lucas Formation In The Michigan Basin, Sukru Nail Apak Aug 1985

Subsurface Stratigrapy And Sedimentologic Control On The Productive Middle Devonian Age Richfield Member Of The Lucas Formation In The Michigan Basin, Sukru Nail Apak

Masters Theses

The depositional system of the Middle Devonian Richfield Member of Lucas Formation in the Michigan Basin was delineated using well logs, cores, drillers' records, and the literature. The Richfield Member was deposited in Sabkha and lagoonal environments characterized by cycles of anhydrite, dolomite, and limestone. Seven significant productive dolomitic zones, interbedded with anhydrite and limestone can be correlated throughout the study area. These zones change laterally to anhydrite towards the west flank and to dense limestone towards the east flank of the basin. Post-depositional diagenetic history of the Richfield was established with the aid of scanning electron microscopy and electron …


Effects Of Urbanization On The Quantity And Quality Of Storm Water Runoff Recharging Through Caves Into The Edwards Aquifer, Bexar County, Texas, George Veni Jul 1985

Effects Of Urbanization On The Quantity And Quality Of Storm Water Runoff Recharging Through Caves Into The Edwards Aquifer, Bexar County, Texas, George Veni

Masters Theses & Specialist Projects

Eighty-nine caves and sinkholes were investigated in the Edwards Aquifer recharge zone in Bexar County, Texas. The study examined their hydrogeologic and topographic origins and distribution, relationships to major fracture traces, quantity of recharge into the aquifer and degree of sensitivity towards degradation of the aquifer’s water quality. Groundwater traces were attempted to determine aquifer flow routes, time of groundwater travel, groundwater volume within conduits, and the aquifer’s capacity for dilution and dispersion of recharged contaminants. Trends in water quality were examined to quantify the volume and variety of contaminants recharged into the aquifer and to determine the effects of …


Dynamics Of Clastic Sedimentation And Watershed Evolution Within A Low-Relief Karst Drainage Basin, Mammoth Cave Region, Kentucky, John D. Pickle Jun 1985

Dynamics Of Clastic Sedimentation And Watershed Evolution Within A Low-Relief Karst Drainage Basin, Mammoth Cave Region, Kentucky, John D. Pickle

Earth and Planetary Sciences ETDs

The hydrology and sedimentology of the Mill Hole drainage basin, a low-relief karst system in the Mammoth Cave Region, Kentucky, depend upon the interactions of surface and groundwater drainages and the distribution of lithologies within the basin. This basin is characterized by sinking streams in the headwaters (Glasgow Uplands) draining into cave rivers beneath the sinkhole-pocked plain (sinkhole plain), which, in turn, flow beneath a sandstone-capped upland (Chester Cuesta) and emerge at base-level springs. Karst windows expose the subterranean drainage within the Chester Cuesta.


Geochemistry Of Alteration And Mineralization Of The Wind River Gold Prospect, Skamania County, Washington, Krista I. Mcgowan Jun 1985

Geochemistry Of Alteration And Mineralization Of The Wind River Gold Prospect, Skamania County, Washington, Krista I. Mcgowan

Dissertations and Theses

The Wind River gold prospect is located in TSN, R7E of Skamania County, Washington, and is an epithermal gold-quartz vein system hosted in volcanic rocks of the Ohanapecosh Formation, a late Eocene to middle Oligocene unit of calcalkaline chemical composition. Andesitic pyroclastic rocks of the Ohanapecosh Formation are the host of mineralization in the study area, and form the lowest of several stratigraphic subunits. These pyroclastic rocks are overlain by two sequences of lava flows which cap the ridges and are folded by an anticlinal warp over the length of Paradise Ridge, plunging gently to the southeast. Toward the west, …


Geology And Geochemistry Of Hydrothermal Alteration, Eastern Portion Of The North Santiam Mining Area, J. Michael Pollock Jun 1985

Geology And Geochemistry Of Hydrothermal Alteration, Eastern Portion Of The North Santiam Mining Area, J. Michael Pollock

Dissertations and Theses

The Ruth Mine is a base-metal vein deposit near the eastern margin of a reported porphyry copper deposit in the Western Cascade Range in Oregon. Uplift of the Western Cascade Range has resulted in a deeply dissected terrain in which more than a kilometer of the stratigraphy overlying the porphyry-style mineralization is preserved and exposed. The stratigraphic units, which are middle Tertiary in age, have been given arbitrary letter designations beginning with the lowest unit (Unit A) through the uppermost unit (Unit D).

Unit A is composed of fragmental rocks of andesitic composition. Overlying and interlayered with Unit A are …


Overview Of Nebraska And The Regional Aquifer From Proceedings Of The 1985 Water Resources Seminar Series, Robert F. Diffendal Jr. Jun 1985

Overview Of Nebraska And The Regional Aquifer From Proceedings Of The 1985 Water Resources Seminar Series, Robert F. Diffendal Jr.

Robert F. Diffendal, Jr., Publications

During each spring semester, the Nebraska Water Resources Center sponsors a Water Resources Seminar Series at the University of Nebraska-Lincoln. The 1985 seminar series was entitled "Aspects of Groundwater Quality." This article appeared in the proceedings.


Aspects Of Groundwater Quality Proceedings 1985 Water Resources Seminar Series Jun 1985

Aspects Of Groundwater Quality Proceedings 1985 Water Resources Seminar Series

Conservation and Survey Division: Faculty and Staff Publications

During each spring semester, the Nebraska Water Resources Center sponsors a Water Resources Seminar Series at the University of Nebraska - Lincoln. The 1985 seminar series was entitled "Aspects of Groundwater Quality".


Groundwater Levels In Nebraska 1984, Michael J. Ellis, Darryll T. Pederson Jun 1985

Groundwater Levels In Nebraska 1984, Michael J. Ellis, Darryll T. Pederson

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Groundwater Levels In Nebraska, 1984, Michael J. Ellis, Darryll T. Pederson Jun 1985

Groundwater Levels In Nebraska, 1984, Michael J. Ellis, Darryll T. Pederson

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Geomorphology Of The Ravi River Near Chamba Town, Himachal Pradesh, India, Bhupinder Singh Marh May 1985

Geomorphology Of The Ravi River Near Chamba Town, Himachal Pradesh, India, Bhupinder Singh Marh

All-Inclusive List of Electronic Theses and Dissertations

Geomorphic history of the study area, which is located in the northwestern Himalaya, is intimately related to the complex geologic and tectonic history of the Himalaya. The Himalayan orogeny started near the CretaceousTertiary boundary when the Indian and Eurasian plates collided. Northern ranges were raised first and the uplift of the southern ranges followed. In the study area, the Pir Panjal was uplifted in the Miocene and the Dhaula Dhar in the Pliocene. It is shown in this research that the pre-Pleistocene history of the study area (the Ravi River basin) is very intimately related to the Himalayan orogeny and …


Spring Flow In A Portion Of Grand Canyon National Park, Arizona, David Bruce Goings May 1985

Spring Flow In A Portion Of Grand Canyon National Park, Arizona, David Bruce Goings

UNLV Theses, Dissertations, Professional Papers, and Capstones

Hermit, Monument, Salt, and Horn Creeks flow through four side canyons of the Colorado River within the Grand Canyon. They lie just west of Grand Canyon Village on the south side of the canyon. Each of these creeks is fed by at least one spring.

Comparisons of flow at each of these springs for a 14 month period, and precipitation on the south rim show a close correlation. The lag period between recharge at the rim and discharge at the springs is less than one month for Hermit Creek and between one and two months for the other three creeks. …


The Petrology And Mineralogy Of Tertiary(?) Olivine Trachyte In The Harrington Peak Quadrangle, Southeastern Idaho, Amanda Shearer-Fullerton May 1985

The Petrology And Mineralogy Of Tertiary(?) Olivine Trachyte In The Harrington Peak Quadrangle, Southeastern Idaho, Amanda Shearer-Fullerton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Harrington Peak Quadrangle is located within the Caribou National Forest of southeast Idaho. Within this quadrangle are outcrops of olivine trachyte of Pliocene(?) age overlying sedimentary rocks of Mississippian to Tertiary age. The region contains thrust faults and later normal faults (generally trending north-south} formed during Basin and Range extension.

The Largest outcrop of olivine trachyte (approximately1 1/2 X 3 km) probably formed as the result of a fissure eruption. Two other outcrop areas show evidence of being sites of local extrusion.

Whole-rock chemical analyses revealed the olivine trachyte to have moderate amounts of SiO2 and Al2O …


Structural Geology Of Eastern Part Of Dairy Ridge Quadrangle And Western Part Of Meachum Ridge Quadrangle, Utah, Val A. Kienast May 1985

Structural Geology Of Eastern Part Of Dairy Ridge Quadrangle And Western Part Of Meachum Ridge Quadrangle, Utah, Val A. Kienast

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A detailed geologic investigation was made of the eastern part of the Dairy Ridge Quadrangle and the western part of the Meachum Ridge Quadrangle, Utah. The area is located in north-central Utah in Rich County. It lies between lat. 41°22'30" N. and lat. 41°28'50" N. and between long. 111°21'40" W. and long. 111°25'15" W. The area measures 13.8 km in the north-south direction and 5.5 km in the east-west direction. It is on the eastern side of the Wasatch Range about 20 km west-southwest of Randolph, Utah.

Stratigraphic units of Precambrian to Cambrian age crop out in the western part …


Petrology And Mineralogy Of Tertiary(?) Volcanic Rocks West And Southwest Of Kelton (Box Elder Co.), Utah, R. L. Voit May 1985

Petrology And Mineralogy Of Tertiary(?) Volcanic Rocks West And Southwest Of Kelton (Box Elder Co.), Utah, R. L. Voit

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Kelton, Utah, area has numerous, isolated basaltic outcrops of probable Tertiary age mostly in the form of cuestas with steep faces displaying columnar joints. One ash-flow tuff is located in the southeastern part of the study area. Basaltic fragments in the tuff indicate that pyroclastic activity was preceded by extrusion of basalt.

Effects of Lake Bonneville on the basaltic outcrops include wave­cut terraces, scarps, and other wave-built forms in low lying areas. Massive carbonate deposits formed at levels of former shorelines of Lake Bonneville. Tertiary and Quaternary deposits cover the low- lying areas between basaltic flows, and consist of …


Sequential Thrusting Beneath The Willard Thrust Fault, Wasatch Mountains, Ogden, Utah, Tad William Schirmer May 1985

Sequential Thrusting Beneath The Willard Thrust Fault, Wasatch Mountains, Ogden, Utah, Tad William Schirmer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The downstructure of viewing geologic maps, balanced and cross sections, and hanging-wall-sequence diagrams are applied to produce the first comprehensive synthesis of the structure below the willard thrust sheet.

Development of the duplex beneath the Willard thrust may be explained with a "piggyback" thrust model where younger thrust slices form below and fold an older, overlying thrust sheet. Progressive failure of the footwall ramp of the Willard thrust sheet extended the sole thrust eastward and produced a duplex consisting of thrust slices (horses) which adhered to the overriding thrust sheet where it ramped from a lower sole thrust to an …


Petrology And Mineralogy Of Tertiary(?) Volcanic Rocks Of Snowville Area, Utah, And Tertiary-Quaternary(?) Volcanic Rocks Of Table Mountain And Holbrook Areas, Idaho, Yunshuen Wang May 1985

Petrology And Mineralogy Of Tertiary(?) Volcanic Rocks Of Snowville Area, Utah, And Tertiary-Quaternary(?) Volcanic Rocks Of Table Mountain And Holbrook Areas, Idaho, Yunshuen Wang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Basalt flows occur in the Snowville area of north-central Utah and the Table Mountain and Holbrook areas of south-central Idaho. All basalt flows are aphanitic in groundmass, and contain olivine, plagioclase, augite, and opaque oxides. They can be distinguished by texture. Snowville basalt has predominantly subophitic to intergranular textures. Table Mountain basalt is fine grained, with stumpy groundmass plagioclase and equant ilmenite crystals. Holbrook basalt has pilotaxitic to intergranular textures, with the presence of plagioclase phenocrysts and characteristic exsolution lamellae in Fe-Ti oxides. The olivine grains in Holbrook area are intensely oxidized to Fe-Ti oxides.

Snowville basalt contains olivine phenocrysts …


Parameters Controlling Sediment Composition Of Modern And Pleistocene Jamaican Reefs, Stephen K. Boss May 1985

Parameters Controlling Sediment Composition Of Modern And Pleistocene Jamaican Reefs, Stephen K. Boss

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Recent carbonate sediments from Jamaican north coast fringing reefs display variation in constituent composition, texture, and mineralogy related to their location on the reef. Samples were collected along lines which traversed the back reef and fore reef (0.5m to 70m).

The sediment is dominated by highly comminuted coral fragments, plates of the calcareous green alga, Halimeda, coralline algae, and the encrusting Foraminifera, Homotrema rubrum, with lesser amounts of other taxonomic groups (Foraminifera; molluscs; echinoderms). Relative abundances of these biotic components vary between sites. Q-mode cluster analysis indicates that constituent composition can be used to delineate the different reef …


Structural Geology Of The Northern Part Of Elkhorn Mountain, Bannock Range, Idaho, Stephen R. Crook May 1985

Structural Geology Of The Northern Part Of Elkhorn Mountain, Bannock Range, Idaho, Stephen R. Crook

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Northern Elkhorn Mountain was unmapped previous to this investigation. The mapped area is located north of Malad City, Idaho, in the Bannock Range. It is within the Basin and Range Province. The mapped area measures 5.4 mi. in the north-south direction and 8.9 mi. in the east-west direction.

The oldest exposed stratigraphic unit, within the mapped area, consists of orthoquartzite and is of Early Cambrian age. Cambrian formations of the mapped area, in ascending order, are as follows: Camelback Mountain Quartzite, Gibson Jack Formation, Elkhead Formation, Bloomington Formation, Nounan Formation, and St. Charles Formation. Units of Ordovician age are the …


The Petrology Of The Early Middle Cambrian Giles Creek And Upper Chandler Formations, Northeastern Amadeus Basin, Central Australia, James A. Deckelman May 1985

The Petrology Of The Early Middle Cambrian Giles Creek And Upper Chandler Formations, Northeastern Amadeus Basin, Central Australia, James A. Deckelman

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Giles Creek and upper Chandler formations crop out in the northeastern Amadeus Basin from the north flank of Ross River syncline south to the Pillar Range, and from the nose of Ooraminna anticline east to the Simpson Desert. Twenty-four sections of the Giles Creek and nineteen sections of the upper Chandler were measured by the author in this area. The Giles Creek lies disconformably above the upper Chandler Formation and conformably below the Shannon Formation. The upper Chandler is conformably underlain by the lower Chandler throughout the area except at Ross River Gorge and Wallaby No. 1 well. There …


Petrology Of The Late Proterozoic(?)-Early Cambrian Arumbera Sandstone, Western Macdonnell Ranges, North-Central Amadeus Basin, Central Australia, Lonn P. Hamp May 1985

Petrology Of The Late Proterozoic(?)-Early Cambrian Arumbera Sandstone, Western Macdonnell Ranges, North-Central Amadeus Basin, Central Australia, Lonn P. Hamp

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Arumbera Sandstone consists of mappable informal units which are repeated in a vertical, cyclic succession. Sandstones of fluvial origin form resistant strike ridges separated by strike valleys, which consist of recessive sandstones and mudrocks of marine origin.

Lithofacies 1a, 2b, and 3a are probably of marine origin in intertidal environments. Trace fossil assemblages in lithofacies 3a suggest Skolithos and Cruziana inchnofacies were present. Lithofacies 1e, 2a, 2c, 3b, and 4a are probably of fluvial origin, as the result of coalescing braided stream deposits. The Arumbera Sandstone probably was deposited in a deltaic environment characterized by low wave energy, a …


The Effect Of Glaciers On Streamflow Variations, Andrew G. Fountain, Wendell V. Tangborn Apr 1985

The Effect Of Glaciers On Streamflow Variations, Andrew G. Fountain, Wendell V. Tangborn

Geology Faculty Publications and Presentations

The effect of temperate glaciers on runoff variations is examined for the North Cascade Mountains of Washington State. The principal influences of glaciers on streamflow are often unexpected contributions to streamflow volume, a delay of the maximum seasonal flow, and a decrease in annual and monthly variation of runoff. The delay of maximum flow is caused by temporary englacial storage of spring meltwater and by peak meltwater production occurring in midsummer. The englacial storage, for one case, is 54% of the potential May runoff. An algorithm is presented that calculates the coefficient of variation of runoff for any arbitrary glacier …