Physical Sciences and Mathematics | Open Access Articles

Unconformities And Age Relationships, Tongue River And Older Members Of The Fort Union Formation (Paleocene), Western Williston Basin, U.S.A., Edward S. Belt, Joseph H. Hartman, John A. Diemer, Timothy J. Kroeger, Neil E. Tibert, H. Allen Curran

Geosciences: Faculty Publications

An unconformable relationship is observed within the Paleocene Fort Union Formation in the western Williston Basin at the contact between the Tongue River Member and the underlying Lebo and Ludlow Members. Isotopic dates and pollen biozone data reported here are integrated with previously published data. A new correlation of these facies results in a revised history of localized depositional and tectonic events. One unconformity occurs at this lithological contact in the Pine Hills (PH), Terry Badlands (TB), and Ekalaka (E) areas west of the Cedar Creek anticline (CCA), and another unconformity occurs at the same lithological contact in the Little …

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Population Recovery And Differential Heat Shock Protein Expression For The Corals Agaricia Agaricites And A. Tenuifolia In Belize, Martha L. Robbart, Paulette M. Peckol, Stylianos P. Scordilis, H. Allen Curran, Jocelyn Brown-Saracino

Geosciences: Faculty Publications

Over recent decades, coral reefs worldwide have experienced severe sea-surface temperature (SST) anomalies. Associated with an El Niño-Southern Oscillation (ENSO) event of 1997-1998, nearly 100% mortality of the space-dominated coral Agaricia tenuifolia was reported at several shelf lagoonal sites of the Belize barrier reef system; a less abundant congener, A. agaricites, had lower mortality rates. We assessed A. agaricites and A. tenuifolia populations at coral reef ridges in the south-central sector of the Belize shelf lagoon and forereef sites to document recovery following the 1998 ENSO event and subsequent passage of Hurricane Mitch. To investigate the difference in heat …

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Marine Anthropogenic Debris Surveys On Hanna Bay And East Beaches, San Salvador Island, Bahamas, 1998–2004, Virginia White, H. Allen Curran

Geosciences: Faculty Publications

Reprinted from: R.L. Davis & D. Gamble, eds., Proceedings of the 12th Symposium on the Geology of the Bahamas and Other Carbonate Regions, San Salvador, Gerace Research Center

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Proterozoic Metamorphism Of The Tobacco Root Mountains, Montana, John T. Cheney, John B. Brady, Kara A. Tierney, Kathleen A. Degraff, Heidi K. Mohlman, Jessica D. Frisch, Christine E. Hatch, Michael L. Steiner, Sarah K. Carmichael, Robin G.M. Fisher, Carrie B. Tuit, Kurt J. Steffen, Pamela Cady, Josh Lowell, Leandra L. Archuleta, Jillian Hirst, Karl W. Wegmann, Brian Monteleone

Geosciences: Faculty Publications

Textures and mineral assemblages of metamorphic rocks of the Tobacco Root Mountains are consistent with metamorphism of all rocks during the Big Sky orogeny (1.77 Ga) at relatively high pressure (P >1.0 GPa) followed by differential reequilibration on a clockwise P-T path at lower pressures (0.6–0.8 GPa). The highest pressures are documented by coarse-grained kyanite and orthopyroxene in aluminous orthoamphibolites, which require P ≥ 1.0 GPa. Other higher-pressure mineral assemblages of note include kyanite + orthoamphibole and kyanite + K-feldspar. Abundant textural evidence for partial melting in pelitic and basaltic rocks includes leucosomes, very large (several cm across) porphyroblasts of …

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40Ar/ 39Ar Ages Of Metamorphic Rocks From The Tobacco Root Mountains Region, Montana, John B. Brady, Dana N. Kovaric, John T. Cheney, Lisa J. Jacob, J. Toby King

Geosciences: Faculty Publications

Measurements of 60 single-grain, UV laser microprobe 40Ar/39Ar total gas ages for hornblende from metamorphic rocks of the Tobacco Root Mountains in southwest Montana yield a mean age of 1.71 ± 0.02 Ga. Measurements of 40Ar/39Ar step-heating plateau ages of three bulk hornblende samples from the Tobacco Root Mountains metamorphic rocks average 1.70 ± 0.02 Ga. We believe that these and the K/Ar or 40Ar/39Ar ages reported by previous workers are cooling ages from a 1.78 to 1.72 Ga, upper-amphibolite to granulite facies, regional metamorphism (Big Sky orogeny) that affected the northwestern portion of the Wyoming province, including the Tobacco …

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Advances In The Geology Of The Tobacco Root Mountains, Montana, And Their Implications For The History Of The Northern Wyoming Province, Tekla A. Harms, John B. Brady, H. Robert Burger, John T. Cheney

Geosciences: Faculty Publications

Integrated studies by Keck Geology Consortium participants have generated many new insights into the Precambrian geology of the Tobacco Root Mountains. We have clarified the tectonic setting and origin of two suites of metamorphic rocks: (1) a quartzofeldspathic gneiss complex with associated metasupracrustal rocks (the combined Indian Creek and Pony–Middle Mountain Metamorphic Suites) that originated in a continental arc setting between 3.35 and 3.2 Ga with subsequent sedimentation and (2) mafic metavolcanic rocks with intercalated metasedimentary rocks (the Spuhler Peak Metamorphic Suite) from a suprasubduction zone ophiolite or backarc basin possibly of Proterozoic age. A poorly preserved metamorphic event at …

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Holocene Tufa-Coated Serpulid Mounds From The Dominican Republic: Depositional And Diagenetic History, With Comparison To Modern Serpulid Aggregates From Baffin Bay, Texas, Bosiljka Glumac, Lisa Berrios, Lisa Greer, H. Allen Curran

Geosciences: Faculty Publications

Ronald D. Lewis and Bruce C. Panuska (eds.) Proceedings of the 11th Symposium on the Geology of the Bahamas and Other Carbonate Regions: San Salvador, Gerace Research Center

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Aragonite Pseudomorphs In High Pressure Marbles Of Syros, Greece, John B. Brady, Michelle J. Markley, John C. Schumacher, John T. Cheney, Grace A. Bianciardi

Geosciences: Faculty Publications

Numerous rod-shaped calcite crystals occur in the blueschist to eclogite facies marbles of Syros, Greece. The rods show a shape-preferred orientation, and the long axes of the rods are oriented at a large angle to foliation. The crystals also have a crystallographic-preferred orientation: calcite c-axes are oriented parallel to the long axes of the rods. Based on their chemical composition, shape, and occurrence in high-pressure marbles, these calcite crystals are interpreted as topotactic pseudomorphs after aragonite that developed a crystallographic-preferred orientation during peak metamorphism. This interpretation is consistent with deformation of aragonite by dislocation creep, which has been observed …

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The Cape Ann Plutonic Suite: A Field Trip For Petrology Classes, John B. Brady, John T. Cheney

Geosciences: Faculty Publications

Cape Ann, because of its proximity to Boston and many universities, has long been a focus of geologic study. Nineteenth century papers that consider mineralogy or petrology of Cape Ann rocks include Prescott (1839), Nichols (1856), Kimball (1860), Gregory (1862), Mudge (1862), Balch (1864), Cooke (1866, 1867), Knowlton (1867), Hyatt (1869, 1871a,b), Hunt (1871), Wadsworth (1878, 1882a,b, 1885), McDaniel (1884), Sears (1888, 1889, 1890a, 1891a,b, 1893a,b, 1894a,b, 1895, 1898), Shaler (1889), Pearce (1893), Penfield and Forbes (1896), and Washington (1898a,b,c, 1899a,b,c,d). More recent studies of note include Wright (1900), Clapp (1921), Warren and McKinstry (1924), Bowen and Schairer (1935), Palache …

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General Geology And Geochemistry Of Metamorphosed Proterozoic Mafic Dikes And Sills, Tobacco Root Mountains, Montana, John B. Brady, Heidi K. Mohlman, Caroline Harris, Sarah K. Carmichael, Lisa J. Jacob, Wilfredo R. Chaparro

Geosciences: Faculty Publications

Just over two billion years ago, basaltic magma intruded rocks of the Pony– Middle Mountain Metamorphic Suite and the Indian Creek Metamorphic Suite that now crop out in the Tobacco Root Mountains of Montana near the northwestern margin of the Wyoming province. Numerous examples can be found of mafic dikes that crosscut layering and gneissic banding, demonstrating that the host rocks were metamorphosed to form the gneissic texture prior to intrusion of the dikes. Although many of the intrusions appear to be sills that followed compositional layering, close inspection reveals low-angle discordance in nearly every case, consistent with rotation of …

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Precambrian Meta-Ultramafic Rocks From The Tobacco Root Mountains, Montana, Kathleen E. Johnson, John B. Brady, William A. Macfarlane, Rebecca B. Thomas, Chris J. Poulsen, M. Jennifer Sincock

Geosciences: Faculty Publications

Meta-ultramafic rocks occur as small (2 to 100 m long), podiform bodies in all three major Precambrian rock suites of the Tobacco Root Mountains of southwest Montana. Most samples consist of a randomly oriented, coarse-grained assemblage of orthopyroxene, olivine, and magnesiohornblende ± spinel, partially replaced by a fine-grained assemblage that may include anthophyllite, talc, cummingtonite, magnesiohornblende, chlorite, serpentine, and/ or magnetite. Blackwall reaction zones of anthophyllite, actinolite, chlorite, and/or biotite surround several of the meta-ultramafic bodies. The absence of clinopyroxene with orthopyroxene limits the metamorphic pressure-temperature history of these rocks to temperatures below ~800 °C. The presence of anthophyllite with …

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Environmental Indicator Proxies From A Mid-Holocene Coral Reef, Enriquillo Valley, Dominican Republic, Gala M.M. Guerard, Lisa Greer, H. Allen Curran

Geosciences: Faculty Publications

No abstract provided.

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Shallow-Water Coral Reefs In Transition: Examples From Belize And The Bahamas, H. Allen Curran, Paulette M. Peckol, Benjamin J. Greenstein, Shannon Ristau, Susan Deyoung

Geosciences: Faculty Publications

Reprinted from: Ronald D. Lewis and Bruce C. Panuska (eds.) Proceedings of the 11th Symposium on the Geology of the Bahamas and Other Carbonate Regions: San Salvador, Gerace Research Center

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Geology Of Long Island, Bahamas: A Field Trip Guide, H. Allen Curran, John E. Mylroie, Douglas W. Gamble, Mark A. Wilson, R. Laurence Davis, Neil E. Sealey, Vincent J. Voegeli

Geosciences: Faculty Publications

See other Smith authored Field Trip Guides of Gerace Research Centre.

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Full-Text Articles in Physical Sciences and Mathematics

Unconformities And Age Relationships, Tongue River And Older Members Of The Fort Union Formation (Paleocene), Western Williston Basin, U.S.A., Edward S. Belt, Joseph H. Hartman, John A. Diemer, Timothy J. Kroeger, Neil E. Tibert, H. Allen Curran

Geosciences: Faculty Publications

Population Recovery And Differential Heat Shock Protein Expression For The Corals Agaricia Agaricites And A. Tenuifolia In Belize, Martha L. Robbart, Paulette M. Peckol, Stylianos P. Scordilis, H. Allen Curran, Jocelyn Brown-Saracino

Geosciences: Faculty Publications

Marine Anthropogenic Debris Surveys On Hanna Bay And East Beaches, San Salvador Island, Bahamas, 1998–2004, Virginia White, H. Allen Curran

Geosciences: Faculty Publications

Geosciences: Faculty Publications

40Ar/ 39Ar Ages Of Metamorphic Rocks From The Tobacco Root Mountains Region, Montana, John B. Brady, Dana N. Kovaric, John T. Cheney, Lisa J. Jacob, J. Toby King

Geosciences: Faculty Publications

Advances In The Geology Of The Tobacco Root Mountains, Montana, And Their Implications For The History Of The Northern Wyoming Province, Tekla A. Harms, John B. Brady, H. Robert Burger, John T. Cheney

Geosciences: Faculty Publications

Holocene Tufa-Coated Serpulid Mounds From The Dominican Republic: Depositional And Diagenetic History, With Comparison To Modern Serpulid Aggregates From Baffin Bay, Texas, Bosiljka Glumac, Lisa Berrios, Lisa Greer, H. Allen Curran

Geosciences: Faculty Publications

Aragonite Pseudomorphs In High Pressure Marbles Of Syros, Greece, John B. Brady, Michelle J. Markley, John C. Schumacher, John T. Cheney, Grace A. Bianciardi

Geosciences: Faculty Publications

The Cape Ann Plutonic Suite: A Field Trip For Petrology Classes, John B. Brady, John T. Cheney

Geosciences: Faculty Publications

General Geology And Geochemistry Of Metamorphosed Proterozoic Mafic Dikes And Sills, Tobacco Root Mountains, Montana, John B. Brady, Heidi K. Mohlman, Caroline Harris, Sarah K. Carmichael, Lisa J. Jacob, Wilfredo R. Chaparro

Geosciences: Faculty Publications

Precambrian Meta-Ultramafic Rocks From The Tobacco Root Mountains, Montana, Kathleen E. Johnson, John B. Brady, William A. Macfarlane, Rebecca B. Thomas, Chris J. Poulsen, M. Jennifer Sincock

Geosciences: Faculty Publications

Environmental Indicator Proxies From A Mid-Holocene Coral Reef, Enriquillo Valley, Dominican Republic, Gala M.M. Guerard, Lisa Greer, H. Allen Curran

Geosciences: Faculty Publications

Shallow-Water Coral Reefs In Transition: Examples From Belize And The Bahamas, H. Allen Curran, Paulette M. Peckol, Benjamin J. Greenstein, Shannon Ristau, Susan Deyoung

Geosciences: Faculty Publications

Geology Of Long Island, Bahamas: A Field Trip Guide, H. Allen Curran, John E. Mylroie, Douglas W. Gamble, Mark A. Wilson, R. Laurence Davis, Neil E. Sealey, Vincent J. Voegeli

Geosciences: Faculty Publications