Geology Commons^™

Karst Subsidence In South-Central Apulia, Southern Italy, Marco Delle Rose, Mario Parise

International Journal of Speleology

Subsidence in the karst of Apulia (Southern Italy), one of the classical karst areas of Italy, is described in this paper. The carbonate rocks that make up the geological structure of the Apulia region are affected by subsidence, which is of different type and intensity depending upon geological, topographical, and hydrogeological conditions. In particular, we discriminate between inland subsidence and coastal subsidence. Inland subsidence is generally restricted to the presence of individual cavities, either empty or partly or totally filled with deposits produced by dissolution of soluble rocks underground. Locally, such subsidence can cause severe effects on anthropogenic structures above. …

Field Trip Guide (For The Nebraska Well Drillers Association) Central Nebraska Geology, James W. Goeke, Robert F. Diffendal Jr., Duane A. Eversoll

Conservation and Survey Division: Faculty and Staff Publications

Field trip guide for the Nebraska Well Drillers Association covering central Nebraska geology from 2002.

Banner County Test Hole Logs, Frank A. Smith

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Creep Critters From Nebraska's Past, Roger K. Pabian

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Impact Spherules From Western Australia: A Textural Analysis Of Really Old Tiny Rocks, Dawn C.S. Ruth

Honors Papers

The fourth shale macroband of the Dales Gorge Member of the Brockman Iron Formation in the Hamersley Basin in Western Australia contains a 2.49 billion years-old impact ejecta layer (Hassler and Simonson,2001). The S4 layer is the least studied Paleoproterozoic impact layer in the Hamersley Basin. It displays textures and replacement minerals not seen in other layers. Analysis of this layer will help our understanding of the processes that form impact ejecta, especially in the Paleoproterozoic.

It is believed that these ejecta settled in a deep basin environment; laterally extensive beds and mud-sized grains are evidence of the deep basin …

Stable Isotopes Of Carbon As An Invaluable Stratigraphic Tool: An Example From The Cambrian Of The Northern Appalachians, Usa, Bosiljka Glumac, Malkah L. Spivak-Birndorf

Geosciences: Faculty Publications

This study illustrates the usefulness of carbon isotopes in stratigraphic interpretations of poorly fossiliferous strata beyond the resolution possible by biostratigraphy. The Upper Cambrian strata of the lower Gorge Formation in northwestern Vermont have been interpreted as highly condensed continental-slope deposits with a hiatus bracketed by the trilobite fauna of the Dunderbergia zone (Steptoean) and the Saukia zone (upper Sunwaptan). This interpretation was based on information from two thin fossiliferous intervals, the occurrence of one of them being unconfirmed in a recent study. Carbon isotopes provide a means for testing this interpretation because marine carbonate rocks deposited during the Steptoean …

Using Simulated Annealing In Geostatistics, Wesley Wells

Theses : Honours

Simulation methods are now used extensively for estimation and prediction in mining and petroleum industries and also in environmental management. In this thesis we describe the method of simulated annealing and examine in detail the GSLIB implementation algorithm SASJM. In the context of two case studies involving both sample and exhaustive data sets, we demonstrate this algorithm and then investigate the effect on the outcome of varying the different algorithm parameters. We also consider the effect of varying the weighting given in the simulated annealing objective function to the reproduction of each of the sample histogram and semivariogram. For the …

Glacial Deposits, Vol. 30, 2001-2002, Department Of Geography-Geology

Glacial Deposits

Newsletter of the Department of Geography-Geology

Subsidence Hazards In Different Types Of Karst: Evolutionary And Speleogenetic Approach, Alexander Klimchouk

International Journal of Speleology

The typology of karst, based on distinguishing the successive stages of general hydrogeological evolution, between which major boundary conditions and the overall circulation pattern change considerably, gives a natural clue, properly to classify and tie together karst breakdown settings, speleogenetic styles and breakdown development mechanisms. Subsidence hazards vary substantially between the different karst types so that classifying individual karst according to typology can provide an integrated general assessment. This provides a useful basis for selection and realization of region- and site-specific assessment schemes and management strategies. Intrastratal karst types, subjacent karst in particular, are most potent in generating subsidence problems. …

The Engineering Classification Of Karst With Respect To The Role And Influence Of Caves, Tony Waltham

International Journal of Speleology

The engineering classification of karst defines various complexities of ground conditions, in terms of the hazards that they provide to potential construction. Karst is divided into five classes (from immature to extreme). The three key parameters within the classification are caves (size and extent), sinkholes (abundance and collapse frequency) and rockhead (profile and relief). As one component of karst, caves are a hazard to foundation integrity, though natural surface collapses over caves are extremely rare. A cave roof is normally stable under engineering loading where the roof thickness is greater than 70% of the cave width. Construction can proceed over …

Cave Breakdown By Vadose Weathering, R. A. L. Osborne

International Journal of Speleology

Vadose weathering is a significant mechanism for initiating breakdown in caves. Vadose weathering of ore bodies, mineral veins, palaeokarst deposits, non-carbonate keystones and impure, altered or fractured bedrock, which is intersected by caves, will frequently result in breakdown. Breakdown is an active, ongoing process. Breakdown occurs throughout the vadose zone, and is not restricted to large diameter passages, or to cave ceilings. The surfaces of disarticulated blocks are commonly coated, rather than having fresh broken faces, and blocks continue to disintegrate after separating from the bedrock. Not only gypsum, but also hydromagnesite and aragonite are responsible for crystal wedging. It …

Karst Breakdown Mechanisms From Observations In The Gypsum Caves Of The Western Ukraine: Implications For Subsidence Hazard Assessment, Alexander Klimchouk, Vjacheslav Andrejchuk

International Journal of Speleology

The term karst breakdown is employed in this paper to denote the totality of processes and phenomena of gravitational and/or hydrodynamic destruction of the ceiling of a karst cavity and of the overlying sediments. It refers not only to the existence of a surface subsidence (collapse) feature but, first of all, to the “internal” (hidden in the subsurface) structures that precede development of a surface form. This study reports and discusses the results of direct mapping and examination of breakdown structures in the gypsum karst of the Western Ukraine, at the level of their origin, i.e. in caves. The accessibility …

Mechanisms Of Karst Breakdown Formation In The Gypsum Karst Of The Fore-Ural Region, Russia (From Observations In The Kungurskaja Cave), Vjacheslav Andrejchuk, Alexander Klimchouk

International Journal of Speleology

The fore-Ural is a classical region of intrastratal gypsum karst. The intensive development of karst in the Permian gypsums and anhydrites causes numerous practical problems, the subsidence hazard being the most severe. Mechanisms of karst breakdown formation were studied in detail in the Kunguskaya Cave area. The cave and its setting are characteristic to the region and, being a site of detalied stationary studies for many years, the cave represents a convenient location for various karst and speleological investigations. Breakdown structures related to cavities of the Kungurskaya Cave type develop by two mechanisms: gravitational (sagging and fall-in of the ceilings …

Stability Appraisal Of The Medvedova Konta Pothole, Jože Kortnik

International Journal of Speleology

Until 1956 the underground details of areas around Pokljuka were practically unknown due to the area’s non-karstic outward appearance. However, the presence of karst phenomena on this Alpine plain is undoubtedly indicated, primarily by the absence of a surface drainage network. A mathematical model was made of the Medvedova konta pothole, in which two different sets of material properties were used, corresponding to the Triassic limestone that forms the bedrock under the greater part of Pokljuka. The model simulates the gradual thinning of the ceiling of the underground hall, from the surface downwards, until its collapse. The paper presents a …

Karstology And The Opening Of Caves During Motorway Construction In The Karst Region Of Slovenia, Martin Knez, Tadej Slabe

International Journal of Speleology

The nature of karst makes constructing a roadway across karst areas a complex task, which is why karstologists take part in motorway construction across Slovenia’s karst. Working with planners, karstologists select the best route on the basis of preliminary research. Then they carry out regular karstological monitoring of the construction, to study newly discovered karst phenomena, mostly caves, and also help builders overcome the challenges of karst in a way that will preserve nature as much as possible. During the recent construction of a section of motorway, more than three hundred caves were encountered within a sixty-kilometre stretch of road. …

Collapse Dolines And Deflector Faults As Indicators Of Karst Flow Corridors, France Šušteršič

International Journal of Speleology

The paper concerns collapse dolines, which appear to be one of the best-defined surface karst phenomena. Despite this appearance, one may find quite different views in the literature, and some of the aspects of their morphogenesis have been overlooked completely. Among these aspects the most obvious is the question of the ongoing development of the closed depression. Five of the most common collapse doline types found in Slovenia are considered in terms of general systems theory, leading to a conclusion that cave roof collapse remains the crucial event in a collapse doline’s development. However, the collapse event itself may be …

Subsidence Hazards As A Consequence Of Dam, Reservoir And Tunnel Construction, Petar Milanovic

International Journal of Speleology

Considering all man-made structures in karst areas, dams, reservoirs and tunnels are the most vulnerable in relation to induced subsidence and caverns. Reservoirs that are located entirely or partially on karstified rocks covered with unconsolidated sediments are especially subsidence-prone. As a consequence of induced subsidence a number of reservoirs in karst areas failed and were never fully filled. Such subsidence formation is very damaging because the development is unpredictable and practically instantaneous. Reservoirs in karst areas may fail to fill despite an extensive site investigation programs and sealing treatment. Every problem is unique and past experiences are never repeated. This …

Collapse Above The World's Largest Potash Mine (Ural, Russia), Vjacheslav Andrejchuk

International Journal of Speleology

This paper reports the results of the study of a huge collapse that occurred in June 1986 within the area of the 3rd Berezniki potash mine (the Verkhnekamsky potash deposit, Ural). Processes that took place between the first appearance of a water inflow through the mine roof and the eventual collapse are reconstructed in detail. The origin and development of a cavity that induced the collapse are revealed. Two factors played a major role in the formation of the collapse: the presence of a tectonic fold/rupture zone with in both the salt sequence and the overburden (the zone of crush …

Force Balance Along An Inland Tributary And Onset To Ice Stream D, West Antarctica, Stephen F. Price, R. A. Bindschadler, Christina L. Hulbe, Donald D. Blankenship

Geology Faculty Publications and Presentations

The transition from inland- to streaming-style ice flow near to and upstream from the onset to Ice Stream D, West Antarctica, is investigated using the force- balance technique. Basal drag provides the majority of the flow resistance over the study area but is substantially modified by non-local stress gradients. Lateral drag increases with distance downstream, balancing ~50-100% of the driving stress at the onset. Longitudinal stress gradients (LSG) are also found to be significant, an observation that distinguishes ice flow in this region from the inland- and streaming-flow regimes that bound it, in which LSG are usually negligible. LSG decrease …

In Situ Hydraulic Testing And Water Quality Sampling In The Hyporheic Zone Of The Columbia River, Hanford Reach, Washington, Evan V. Arntzen

Dissertations and Theses

Several chemical and radiological contaminants are present in an unconfined aquifer underlying the U.S. Department of Energy's Hanford Site in southeast Washington State. Hexavalent chromium [Cr(VI)], previously used as an anticorrosive in plutonium production reactors on the shoreline of the Columbia River, is of particular concern because of its conservative nature, toxicity to humans and aquatic life, and proximity to protected salmon spawning habitat. Hydrogeologic data are abundant from the unconfined aquifer, but are lacking from the hyporheic zone through which Cr(VI) is transported into the river. A hydrogeologic study was conducted near one known Cr(VI) plume to determine the …

Field Trip Guide (For The Nebraska Well Drillers Association) Southwestern Nebraska Geology, D. Eversoll

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Scotts Bluff County Test Hole Logs, Vincent H. Dreeszen, Steven S. Sibray, Frank A. Smith

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Derivation Of A Tasselled Cap Transformation Based On Landsat 7 At-Satellite Reflectance, C. Huang, Wylie L. Yang, Collin Homer, G. Zylstra

United States Geological Survey: Staff Publications

A new tasselled cap transformation based on Landsat 7 at-satellite reflectance was developed. This transformation is most appropriate for regional applications where atmospheric correction is not feasible. The brightness, greenness and wetness of the derived transformation collectively explained over 97% of the spectral variance of the individual scenes used in this study.

Strontium Isotopic Signatures Of The Streams And Lakes Of Taylor Valley, Southern Victoria Land, Antarctica: Chemical Weathering In A Polar Climate, W. B. Lyons, Carmen A. Nezat, Larry V. Benson, Thomas D. Bullen, Elizabeth Y. Graham, Jesicca Kidd, Kathleen A. Welch, James M. Thomas

United States Geological Survey: Staff Publications

We have collected and analyzed a series of water samples from three closed-basin lakes (Lakes Bonney, Fryxell, and Hoare) in Taylor Valley, Antarctica, and the streams that flow into them. In all three lakes, the hypolimnetic waters have different ⁸⁷Sr/⁸⁶Sr ratios than the surface waters, with the deep water of Lakes Fryxell and Hoare being less radiogenic than the surface waters. The opposite occurs in Lake Bonney. The Lake Fryxell isotopic ratios are lower than modern-day ocean water and most of the whole-rock ratios of the surrounding geologic materials. A conceivable source of Sr to the system …

A High Resolution Gravity Survey Of The Lake St. Martin Impact Structure, Manitoba, Canada, Christina Davids

Theses and Dissertations

There are roughly 160 known impact craters listed in the Cratering Database (Earth Impact Database, 2002) of these approximately 20% are buried structures. Geophysical methods of investigation are used to study buried impact structures and add to the growing knowledge base of crater properties. Approximately three to five craters are discovered each year, some of which may be identified through gravity anomalies. A high-resolution gravity survey of the Lake St. Martin impact structure, southern Manitoba, Canada, was conducted to further interpret the structure's gravity anomaly. Previous studies have suggested two different crater diameters for Lake St. Martin, one of 23-km …

Arctic Ice Export Events And Their Potential Impact On Global Climate During The Late Pleistocene, Dennis A. Darby, Jens F. Bischof, Robert F. Spielhagen, Steven A. Marshall, Stephen W. Herman

OES Faculty Publications

Ice sheets in the North American Arctic and, to a lesser extent, those in northern Eurasia calved large quantities of icebergs that drifted through Fram Strait into the Greenland Sea several times during the late Pleistocene. These icebergs deposited Fe oxide grains (45-250 mum) and coarse lithic clasts >250 mum matched to specific circum-Arctic sources. Four massive Arctic iceberg export events are identified from the Laurentide and the Innuitian ice sheets, between 14 and 34 ka (calendar years) in a sediment core from Fram Strait. These relatively short duration (<1-4 kyr) events contain 3-5 times the background levels of Fe oxide grains. They began suddenly, as indicated by a steep rise in the number of grains matched to an ice sheet source, suggesting rapid purges of ice through Fram Strait, due perhaps to collapse of ice sheets. The larger events from the northwestern Laurentide ice sheet are preceded by events from the Innuitian ice sheet. Despite the chronological uncertainties, the Arctic export events appear to occur prior to Heinrich events.

A New Occurrence Of Archaeoscyphia Pulchra (Bassler) From The Ordovician Of Western Canada, J. Keith Rigby, Godfrey S. Nowlan, Peter A. Rowlands

Faculty Publications

A few specimens of the ornate anthaspidellid demosponge, Archaeoscyphia pulchra (Bassler), have been collected from the Lower Ordovician Outram Formation or Skoki Formation, from a saddle at the head of South Rice Brook in northeastern British Columbia. This is the first report of the flanged-appearing annulate, steeply obconical sponge in western Canada, although it has been reported from the Mingan Islands of Quebec and was initially described from Nevada, in the western United States. The taxon has also been reported as other species of Archaeoscyphia from Ordovician rocks of Missouri and from the San Juan region of Argentina.

The Emplacement Age Of Gabbroic Rocks And Associated Granitoids Of The Liganga-Msanyo Complex, South Eastern Tanzania, M. A. H. Maboko

Tanzania Journal of Science

The Msanyo Gabbro and the associated Mdando granitoids, which intrude Paleoproterozoic high-grade metamorphic rocks of the Ubendian Belt in southern Tanzania, yield imprecise Sm-Nd whole rock isochron ages of 1608±134 Ma (ε (Nd) = 2.1) and 1642±100 Ma (ε (Nd) = 1.6), respectively. These ages are indistinguishable at the 95% confidence level, indicating that the two rock suites were intruded at the same time. A more precise estimate of the time of emplacement is provided by a 5-point mineral isochron age of 1505±42 obtained from one of the gabbro samples. Calculated initial ε (Nd) values and mean crustal residence ages …

Tectonic Setting And Uplift Analysis Of The Pangani Rift Basin In Northern Tanzania Using Apatite Fission Track Thermochronology, E. I. Mbede

Tanzania Journal of Science

Thirty four new Apatite Fission Track (AFT) ages and 32 track length distributions from samples of basement rocks flanking the Pangani rift, East African Rift System (EARS) are presented, in an attempt to elucidate the uplift and erosion of the rift flanks. The ages fall in the range of 207±15 to 48±4 Ma, spanning from Early Jurassic to Early Tertiary. These ages are much younger than the last termal event in the Mozambique belt that form the basement complex and are interpreted to represent the most recent tectonic events. Track length (TL) distributions suggest that uplift and erosion of the …

Bulletin No. 37: Living Resources And Habitats Of The Lower Connecticut River, Glenn D. Dreyer, Marcianna Caplis

Bulletins

No abstract provided.