University Ox Nevada Reno Geology, Geotechnical Properties And
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Faults and Joints
133 JOINTS Joints (also termed extensional fractures) are planes of separation on which no or undetectable shear displacement has taken place. The two walls of the resulting tiny opening typically remain in tight (matching) contact. Joints may result from regional tectonics (i.e. the compressive stresses in front of a mountain belt), folding (due to curvature of bedding), faulting, or internal stress release during uplift or cooling. They often form under high fluid pressure (i.e. low effective stress), perpendicular to the smallest principal stress. The aperture of a joint is the space between its two walls measured perpendicularly to the mean plane. Apertures can be open (resulting in permeability enhancement) or occluded by mineral cement (resulting in permeability reduction). A joint with a large aperture (> few mm) is a fissure. The mechanical layer thickness of the deforming rock controls joint growth. If present in sufficient number, open joints may provide adequate porosity and permeability such that an otherwise impermeable rock may become a productive fractured reservoir. In quarrying, the largest block size depends on joint frequency; abundant fractures are desirable for quarrying crushed rock and gravel. Joint sets and systems Joints are ubiquitous features of rock exposures and often form families of straight to curviplanar fractures typically perpendicular to the layer boundaries in sedimentary rocks. A set is a group of joints with similar orientation and morphology. Several sets usually occur at the same place with no apparent interaction, giving exposures a blocky or fragmented appearance. Two or more sets of joints present together in an exposure compose a joint system. -
Virgin Islands National Park Geologic Resources Inventory Report
National Park Service U.S. Department of the Interior Natural Resource Program Center Virgin Islands National Park Geologic Resources Inventory Report Natural Resource Report NPS/NRPC/GRD/NRR—2010/226 THIS PAGE: Underwater ecosystems including coral reefs are a primary natural resource at Virgin Islands National Park. National Park Service photograph. ON THE COVER: This view of Trunk Bay shows the steep slopes characteristic of Virgin Islands Na- tional Park. National Park Service photo- graph courtesy Rafe Boulon (Virgin Islands National Park). Virgin Islands National Park Geologic Resources Inventory Report Natural Resource Report NPS/NRPC/GRD/NRR—2010/226 Geologic Resources Division Natural Resource Program Center P.O. Box 25287 Denver, Colorado 80225 July 2010 U.S. Department of the Interior National Park Service Natural Resource Program Center Fort Collins, Colorado The National Park Service, Natural Resource Program Center publishes a range of reports that address natural resource topics of interest and applicability to a broad audience in the National Park Service and others in natural resource management, including scientists, conservation and environmental constituencies, and the public. The Natural Resource Report Series is used to disseminate high-priority, current natural resource management information with managerial application. The series targets a general, diverse audience, and may contain NPS policy considerations or address sensitive issues of management applicability. All manuscripts in the series receive the appropriate level of peer review to ensure that the information is scientifically credible, technically accurate, appropriately written for the intended audience, and designed and published in a professional manner. This report received informal peer review by subject-matter experts who were not directly involved in the collection, analysis, or reporting of the data. -
Columnar Joints
Columnar Joints The formation of regular shapes by natural processes makes some of the world's most intriguing wonders. The presence of long, mostly six-sided columns (called columnar joints) in cooled lavas is one of those wonders. No one who has seen the awesome grooved structure in Devil's Tower in Wyoming or the Devil's Post Pile in California, can forgot this feature. What about a cooling mass of magma could cause such symmetrical columnar joints? A similar phenomenon can be seen when a mud puddle dries. As it loses water, the mud cracks in symmetric shapes, forming mud polygons. This is because the lose of water causes the mud to shrink. That contraction is relieved by breaking as the dry mud becomes brittle. When things contract like this, they naturally seek the most stable position, For mud, that is a system of natural polygons, separated by vertical cracks. Basalt and other lavas behave similarly. As lava cools, it doesn't dry out like mud, but it does shrink. As it becomes cold and brittle, the lava contracts and relieves the stress by cracking. The cracking produces a polygonal pattern that extends through the lava flow. As weathering cuts into lava, the rock breaks along the joints, exposing this geometric regularity. Although many of the polygons are six- sided, four, five, seven or eight sides columns are also relatively common. The degree and perfection to which this is developed depends on the thickness and composition of the lava and how fast it cools. The long sides of the column form parallel to the direction of heat loss as the lava cools. -
Iceland and the People There, in Particular Ditta, Helga and the Landmannalaugar Crew for Looking After Me and Taking Us in During a Storm and Feeding Us Cake
Open Research Online The Open University’s repository of research publications and other research outputs Cooling Fractures in Lavas: Mechanisms and Environments of Formation Thesis How to cite: Forbes, Anne (2013). Cooling Fractures in Lavas: Mechanisms and Environments of Formation. PhD thesis The Open University. For guidance on citations see FAQs. c 2013 The Author https://creativecommons.org/licenses/by-nc-nd/4.0/ Version: Version of Record Link(s) to article on publisher’s website: http://dx.doi.org/doi:10.21954/ou.ro.0000f113 Copyright and Moral Rights for the articles on this site are retained by the individual authors and/or other copyright owners. For more information on Open Research Online’s data policy on reuse of materials please consult the policies page. oro.open.ac.uk U N P>€ ST Rl CT&D Cooling fractures in lavas: mechanisms and environments of formation A thesis submitted for the degree of Doctor of Philosophy in the Earth Sciences By Anne Forbes BA, MSci (Cantab) Department of Environment, Earth and Ecosystems, The Open University December 2012 D ate ol- (S'abr^A'Ssvon; 21 [)2(£n\b£f 2d Date oj l\warcte 3l Jutej 2.o# ProQuest Number: 13835945 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a com plete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest ProQuest 13835945 Published by ProQuest LLC(2019). -
Hydrothermal Alteration and Mass Exchange in the Hornblende Latite Porphyry, Rico, Colorado
Contrib Mineral Petrol (t 994) 116 : 199-215 Contributions to Mineralogy and Petrology Springer-Verlag 1994 Hydrothermal alteration and mass exchange in the hornblende latite porphyry, Rico, Colorado Peter B. Larson 1, Charles G. Cunningham 2, and Charles W. Naeser 3 1 Department of Geology, Washington State University, Pullman, WA 99164-2812, USA 2 United States Geological Survey, 959 National Center, Reston, VA 22092, USA 3 United States Geological Survey, MS 963, Denver Federal Center, Denver, CO 80225, USA Received March 29, 1992 / Accepted June 30, 1993 Abstract. The Rico paleothermal anomaly, southwestern component in the proximal facies reacted while the pri- Colorado, records the effects of a large hydrothermal mary plagioclase was still unreacted, but the ratio for system that was active at 4 Ma. This hydrothermal sys- these assemblages increased to 1.51 when the plagioclase tem produced the deep Silver Creek stockwork Mo de- entered the reaction paragenesis. Plagioclase reaction posit, which formed above the anomaly's heat source, during distal propylitic alteration resulted in pseudo- and shallower base and precious-metal vein and replace- morphic albite mixed with illite and a loss of NazO. ment deposits. A 65 Ma hornblende latite porphyry is CaO is lost in the distal facies as hornblende reacts to present as widespread sills throughout the area and pro- chlorite, although some calcium may be fixed in calcite. vided a homogeneous material that recorded the effects CaO is added to the proximal facies as the quantity of the hydrothermal system up to 8 km from the center. of chlorite replacing hornblende increases and epidote Hydrothermal alteration in the latite can be divided into and calcite are produced. -
Description of Map Units
GEOLOGIC MAP OF THE LATIR VOLCANIC FIELD AND ADJACENT AREAS, NORTHERN NEW MEXICO By Peter W. Lipman and John C. Reed, Jr. 1989 DESCRIPTION OF MAP UNITS [Ages for Tertiary igneous rocks are based on potassium-argon (K-Ar) and fission-track (F-T) determinations by H. H. Mehnert and C. W. Naeser (Lipman and others, 1986), except where otherwise noted. Dates on Proterozoic igneous rocks are uranium-lead (U-Pb) determinations on zircon by S. A. Bowring (Bowring and others, 1984, and oral commun., 1985). Volcanic and plutonic rock names are in accord with the IUGS classification system, except that a few volcanic names (such as quartz latite) are used as defined by Lipman (1975) following historic regional usage. The Tertiary igneous rocks, other than the peralkaline rhyolites associated with the Questa caldera, constitute a high-K subalkaline suite similar to those of other Tertiary volcanic fields in the southern Rocky Mountains, but the modifiers called for by some classification schemes have been dropped for brevity: thus, a unit is called andesite, rather than alkali andesite or high-K andesite. Because many units were mapped on the basis of compositional affinities, map symbols were selected to emphasize composition more than geographic identifier: thus, all andesite symbols start with Ta; all quartz latites with Tq, and so forth.] SURFICIAL DEPOSITS ds Mine dumps (Holocene)—In and adjacent to the inactive open pit operation of Union Molycorp. Consist of angular blocks and finer debris, mainly from the Sulphur Gulch pluton Qal Alluvium (Holocene)—Silt, sand, gravel, and peaty material in valley bottoms. -
Columnar Jointing on Mars: Earth Analog Studies M
43rd Lunar and Planetary Science Conference (2012) 2726.pdf Columnar Jointing on Mars: Earth Analog Studies M. P. Milazzo?, D. K. Weiss, B. Jackson, J. Barnes, ?U.S. Geological Survey, Astrogeology Science Center, 2255 N. Gemini Dr., Flagstaff, AZ, 86001 ([email protected]) Introduction The High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO) discovered multi-tiered columnar jointing on Mars [1] (Fig. 1). Since the initial discovery image, more columns, some with entablature, have been observed at multiple sites [2] on Mars. Nearly all of these sites oc- cur in the uplifted walls of impact craters in regions with histories of flood volcanism. The local geologic history leads to the suggestion that these are columnar basalts [1]. Extension of the modeling of terrestrial colum- nar lavas by [3] and [4] to the martian columnar joints and entablature discussed in [1] (and seen in observation PSP 006985 2020; Fig. 1) suggests that the lavas cooled, in the presence of water, over a period of approximately 2 to 14 years, depending on the details of joint formation. Figure 1: Columns seen in the wall of the impact crater at the discovery site, in Marte Vallis between Elysium and Role of Water in the Formation of Terres- Amazonis plana. Observation ID: PSP 006985 2020 trial Columnar Lavas [3] and [4] found that in terrestrial columnar lavas a ma- jor factor controlling the width of columns (entablature 40.0 or colonnade) is the cooling rate of the layer of plas- 35.0 tic lava just beneath (for a horizontally-oriented cooling front) the solidified lava. -
Petrography Edward F
Chapter 4 Petrography Edward F. Stoddard A petrographic study was taken in order to help determine the sources of lithic artifacts found at archaeological sites on Fort Bragg. In the first phase of the study, known and suspected archaeological quarry sites in the central Piedmont of North Carolina were visited. From each quarry, hand specimens were collected and petrographic thin sections were examined in an attempt to establish a basis for distinguishing among the quarries. If material from each quarry was sufficiently distinctive, then quarry sources could potentially be matched with Fort Bragg lithic artifacts. Seventy-one samples from 12 quarry zones were examined (Table 4.1). Thirty- one of these samples are from five quarry zones in the Uwharrie Mountains region; 20 of these were collected and described previously by Daniel and Butler (1996). Forty specimens were collected from seven additional quarry zones in Chatham, Durham, Person, Orange, and Cumberland Counties. All quarries are within the Carolina Terrane, except the Cumberland County quarry, which occurs in younger sedimentary material derived primarily from Carolina Terrane outcrops. Rocks include both metavolcanic and metasedimentary types. Compositionally, most metavolcanic rocks are dacitic and include flows, tuffs, breccias, and porphyries. Metasedimentary rocks are metamudstone and fine metasandstone. The Uwharrie quarries are divided into five zones: Eastern, Western, Southern, Asheboro, and Southeastern. The divisions are based primarily on macroscopic petrography and follow the results of Daniel and Butler (1996); the Uwharries Southeastern zone was added in this study. Each of the Uwharrie quarry zones represents three to six individual quarries in relatively close proximity. Rock specimens are all various felsic metavolcanic rocks, but zones may be distinguished based upon mineralogy and texture. -
Field-Trip Guide to the Vents, Dikes, Stratigraphy, and Structure of the Columbia River Basalt Group, Eastern Oregon and Southeastern Washington
Field-Trip Guide to the Vents, Dikes, Stratigraphy, and Structure of the Columbia River Basalt Group, Eastern Oregon and Southeastern Washington Scientific Investigations Report 2017–5022–N U.S. Department of the Interior U.S. Geological Survey Cover. Palouse Falls, Washington. The Palouse River originates in Idaho and flows westward before it enters the Snake River near Lyons Ferry, Washington. About 10 kilometers north of this confluence, the river has eroded through the Wanapum Basalt and upper portion of the Grande Ronde Basalt to produce Palouse Falls, where the river drops 60 meters (198 feet) into the plunge pool below. The river’s course was created during the cataclysmic Missoula floods of the Pleistocene as ice dams along the Clark Fork River in Idaho periodically broke and reformed. These events released water from Glacial Lake Missoula, with the resulting floods into Washington creating the Channeled Scablands and Glacial Lake Lewis. Palouse Falls was created by headward erosion of these floodwaters as they spilled over the basalt into the Snake River. After the last of the floodwaters receded, the Palouse River began to follow the scabland channel it resides in today. Photograph by Stephen P. Reidel. Field-Trip Guide to the Vents, Dikes, Stratigraphy, and Structure of the Columbia River Basalt Group, Eastern Oregon and Southeastern Washington By Victor E. Camp, Stephen P. Reidel, Martin E. Ross, Richard J. Brown, and Stephen Self Scientific Investigations Report 2017–5022–N U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior RYAN K. ZINKE, Secretary U.S. -
A Tale of Two Walker Lane Pull-Apart Basins in the Ancestral Cascades Arc, Central Sierra Nevada, California GEOSPHERE; V
Research Paper THEMED ISSUE: Origin and Evolution of the Sierra Nevada and Walker Lane GEOSPHERE A tale of two Walker Lane pull-apart basins in the ancestral Cascades arc, central Sierra Nevada, California GEOSPHERE; v. 14, no. 5 Cathy J. Busby1, K. Putirka2, Benjamin Melosh3, Paul R. Renne4,5, Jeanette C. Hagan6, Megan Gambs7, and Catherine Wesoloski1 1Department of Earth and Planetary Science, University of California, Davis, California 95616, USA https://doi.org/10.1130/GES01398.1 2Department of Earth and Environmental Sciences, California State University, Fresno, California 93720, USA 3U.S. Geological Survey, Menlo Park, California 94025, USA 15 figures; 1 table; 1 set of supplemental files; 4Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709, USA 2 oversized figures 5Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA 6Exxon Mobil, Houston, Texas 77389, USA 7School of Oceanography, University of Washington, Seattle, Washington 98105, USA CORRESPONDENCE: cjbusby@ ucdavis .edu CITATION: Busby, C.J., Putirka, K., Melosh, B., Renne, P.R., Hagan, J.C., Gambs, M., and Wesoloski, ABSTRACT ter is dominated by Stanislaus Group basalt, trachybasaltic andesite, trachy- C., 2018, A tale of two Walker Lane pull-apart basins andesite, and andesite. Climactic eruptions at its southern end produced the in the ancestral Cascades arc, central Sierra Nevada, We integrate new geochronological, petrographic, and geochemical data Little Walker caldera and its Stanislaus Group trachydacite -
Lexicon of Stratigraphic Names Used in South-Central Colorado Amd Northern New Mexico, San Luis Basin Christina Lochman-Balk and James E
New Mexico Geological Society Downloaded from: http://nmgs.nmt.edu/publications/guidebooks/22 Lexicon of stratigraphic names used in south-central Colorado amd northern New Mexico, San Luis Basin Christina Lochman-Balk and James E. Bruning, 1971, pp. 101-111 in: San Luis Basin (Colorado), James, H. L.; [ed.], New Mexico Geological Society 22nd Annual Fall Field Conference Guidebook, 340 p. This is one of many related papers that were included in the 1971 NMGS Fall Field Conference Guidebook. Annual NMGS Fall Field Conference Guidebooks Every fall since 1950, the New Mexico Geological Society (NMGS) has held an annual Fall Field Conference that explores some region of New Mexico (or surrounding states). Always well attended, these conferences provide a guidebook to participants. Besides detailed road logs, the guidebooks contain many well written, edited, and peer-reviewed geoscience papers. These books have set the national standard for geologic guidebooks and are an essential geologic reference for anyone working in or around New Mexico. Free Downloads NMGS has decided to make peer-reviewed papers from our Fall Field Conference guidebooks available for free download. Non-members will have access to guidebook papers two years after publication. Members have access to all papers. This is in keeping with our mission of promoting interest, research, and cooperation regarding geology in New Mexico. However, guidebook sales represent a significant proportion of our operating budget. Therefore, only research papers are available for download. Road logs, mini-papers, maps, stratigraphic charts, and other selected content are available only in the printed guidebooks. Copyright Information Publications of the New Mexico Geological Society, printed and electronic, are protected by the copyright laws of the United States. -
A Map of Important Geological Sites of Slovakia
A MAP OF IMPORTANT GEOLOGICAL SITES OF SLOVAKIA P. LIŠČÁK, M. POLÁK, P. PAUDITŠ and I. BARÁTH Geological Survey of the Slovak Republic Abstract: The Landscape Atlas of the Slovak Republic is being prepared at the Ministry of the Environment of the Slovak Republic comprising also geological aspects of the environment. The map of geological curiosities at 1 : 1 000 000 scale is the compound of the chapter 8 devoted to protected territories and natural resources (responsible editor: RNDr. Tatiana Hrnčiarová, CSc.). Geological sites require different criteria when trying to make them closer for the laic publics, depending on the specific subject being reviewed. Key words: geosites, geological heritage Introduction The global network of more than 30,000 protected areas covering 13.2 million km2, an equivalent of almost 9% of the world’s land area (Green and Paine 1997) encompasses substantial representation of the Earth’s geological heritage. The definition of Geosite or “Geotope” comprises elements of the landscape of particular characteristics, corresponding to significant genetic features (lithology, morphology, structure, etc.) or showing evident scientific, cultural or aesthetic value. Besides geosites, natural values comprise other valuable features, plant and animal species and their habitats, ecosystems, parts of natural and cultural landscape and historical gardens, parks or even trees. These objects of living nature are more familiar to wide publics, and more attention has been given to them. Geoconservation is a rather young aspect of nature and landscape conservation, which started in the 19th century. In the course of time, nature and landscape conservation became a generally accepted issue in our societies.