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Articles 121 - 150 of 219
Full-Text Articles in Geology
Metamorphic Style And Development Of The Blueschist- To Eclogite-Facies Rocks, Cyclades, Greece, John C. Schumacher, John B. Brady, John T. Cheney
Metamorphic Style And Development Of The Blueschist- To Eclogite-Facies Rocks, Cyclades, Greece, John C. Schumacher, John B. Brady, John T. Cheney
Geosciences: Faculty Publications
The island of Syros, Greece is part of the Attic-Cycladic blueschist belt, formed during Mesozoic Eurasia-Africa subduction. The rocks of Syros can be broadly divided into three tectono-stratigraphic units: (I) metamorphosed sedimentary and volcanic rocks (marble-schist sequence), (II) remnants of oceanic crust with fault-bounded packages of blueschist/eclogite-facies mafic rocks and serpentinite (mafic-ultramafic rocks) and (III) the Vari gneiss, which is a tectonic klippe. Low-temperature, high-pressure assemblages are found on several islands in the Cyclades. The best preserved of these rocks are on Syros and Sifnos islands. Mineral compositions and peak metamorphic assemblages are similar on both islands. Both islands are …
Stable Isotope Analysis Of Upper Tithonian Limestones With Dinosaur Footprints From Kirmenjak Quarry (Istria, Croatia), Blanka Cvetko Tešović, Aleksandar Mezga, Bosiljka Glumac
Stable Isotope Analysis Of Upper Tithonian Limestones With Dinosaur Footprints From Kirmenjak Quarry (Istria, Croatia), Blanka Cvetko Tešović, Aleksandar Mezga, Bosiljka Glumac
Geosciences: Faculty Publications
The Kirmenjak locality of western Istria, Croatia, represents the oldest evidence of a dinosaur presence on the Adriatic-Dinaridic Carbonate Platform (ADCP). In a quarry at this locality, almost a thousand sauropod footprints are recognized in one distinctive trackbearing horizon within the Upper Tithonian limestones. The stable isotopes of oxygen and carbon, in conjunction with microfacies analysis of carbonate rocks exposed in this quarry, unravel details about the marginal marine or coastal environments in which sauropods left their footprints. Rocks from the trackbearing horizon, and laterally adjacent area, represent intertidal fenestral mudstones that form the top of a shallowing-upward succession, capped …
Fossil Palm Frond And Tree Trunk Molds: Occurrence And Implications For Interpretation Of Bahamian Quaternary Carbonate Eolianites, H. Allen Curran, Mark A. Wilson, John E. Mylroie
Fossil Palm Frond And Tree Trunk Molds: Occurrence And Implications For Interpretation Of Bahamian Quaternary Carbonate Eolianites, H. Allen Curran, Mark A. Wilson, John E. Mylroie
Geosciences: Faculty Publications
Molds of palm fronds and vertical, cylindrical structures interpreted as molds of palm tree trunks were reported from Holocene and upper Pleistocene carbonate eolianites on several islands in the Bahamas in the early 1990s. As a result of recent discoveries described herein, palm frond and tree trunk molds are now known to be widespread in Bahamian eolianites, including Holocene beds on Cat Island, Eleuthera, Lee Stocking Island of the Exuma Cays, Long Island, and Stocking Island offshore from Georgetown, Exuma. Late Pleistocene occurrences are known from Eleuthera, Long Island, Norman's Pond Cay of the Exuma Cays, and San Salvador Island. …
Multiple Sedimentary Sequences, Bird Tracks And Lagoon Beaches In Last Interglacial Oolites, Boiling Hole, North Eleuthera Island, Bahamas, Pascal Kindler, H. Allen Curran, Damiel Marty, Elias Samankassou
Multiple Sedimentary Sequences, Bird Tracks And Lagoon Beaches In Last Interglacial Oolites, Boiling Hole, North Eleuthera Island, Bahamas, Pascal Kindler, H. Allen Curran, Damiel Marty, Elias Samankassou
Geosciences: Faculty Publications
Our review of the last interglacial (Marine Isotope Stage 5e) stratigraphic record from the Boiling Hole exposure in northern Eleuthera Island, Bahamas, revealed the occurrence of two vertically stacked shallowing-upward sequences of oolitic coastal deposits showing beach facies at about 3 and 6 m above mean sea level, respectively. These beach strata dip towards the bank interior and the upper one includes a paleosurface on top of an oolitic grainstone bed with a 2-m-long bird trackway. These fossil beaches correspond to two distinctive sea-level highstands during the last interglacial that could have possibly reached +5 and +8 m above modem …
Geology Of Rum Cay, Bahamas: A Field Trip Guide, John E. Mylroie, James L. Carew, H. Allen Curran, Jonathan B. Martin, Thomas A. Rothfus, Neil E. Sealey, Fredrick D. Siewers
Geology Of Rum Cay, Bahamas: A Field Trip Guide, John E. Mylroie, James L. Carew, H. Allen Curran, Jonathan B. Martin, Thomas A. Rothfus, Neil E. Sealey, Fredrick D. Siewers
Geosciences: Faculty Publications
See other Smith authored Field Trip Guides of Gerace Research Centre.
Biogenic Macroporosity And Lts Lattice Boltzmann Method Permeability In The Karst Biscayne Aquifer, Kevin J. Cunningham, Michael C. Sukop, Haibo Huang, Pedro F. Alvarez, H. Allen Curran, Michael A. Wacker, Lee J. Florea, Robert A. Renken, Joann F. Dixon
Biogenic Macroporosity And Lts Lattice Boltzmann Method Permeability In The Karst Biscayne Aquifer, Kevin J. Cunningham, Michael C. Sukop, Haibo Huang, Pedro F. Alvarez, H. Allen Curran, Michael A. Wacker, Lee J. Florea, Robert A. Renken, Joann F. Dixon
Geosciences: Faculty Publications
We focus on two major problems in the study of paleokarst of the Biscayne aquifer in southeastem Florida: ( 1 ), current conceptual models of karst aquifers do not adequately characterize much of the eogenetic rnacropore system within the carbonate rocks of the Biscayne aquifer, and (2) standard laboratory core-analysis rnethods cannol be used lo accurately measure the permeability of highly macroporous carbonate core samples.
Strain And Rotation Rate From Gps In Tibet, Anatolia, And The Altiplano, Richard W. Allmendinger, Robert Reilinger, John P. Loveless
Strain And Rotation Rate From Gps In Tibet, Anatolia, And The Altiplano, Richard W. Allmendinger, Robert Reilinger, John P. Loveless
Geosciences: Faculty Publications
Deformation measured by regional GPS networks in continental plateaus reflects the geologic and tectonic variability of the plateaus. For two collisional plateaus (Tibet and Anatolia) and one noncollisional (the Altiplano), we analyze the regional strain and rotation rate by inverting GPS velocities to calculate the full two-dimensional velocity gradient tensor. To test the method, we use gridded velocities determined from an elastic block model for the eastern Mediterranean/Middle East region and show that to a first order, the deformation calculated directly from the GPS vectors provides an accurate description of regional deformation patterns. Principal shortening and extension rate axes, vertical …
Late Cambrian (Steptoean) Sedimentation And Responses To Sea-Level Change Along The Northeastern Laurentian Margin: Insights From Carbon Isotope Stratigraphy, Bosiljka Glumac, Laurel E. Mutti
Late Cambrian (Steptoean) Sedimentation And Responses To Sea-Level Change Along The Northeastern Laurentian Margin: Insights From Carbon Isotope Stratigraphy, Bosiljka Glumac, Laurel E. Mutti
Geosciences: Faculty Publications
Carbon isotopes are applied as tools for stratigraphic correlation of poorly fossiliferous Upper Cambrian carbonate strata in the northern U.S. Appalachians. Upper Cambrian (Steptoean) marine carbonate rocks record a significant global positive carbon isotope excursion (δ 13C = +4‰-5‰ Vienna Peedee belemnite [VPDB]), the timing of which is well documented in fossiliferous sections elsewhere. The Steptoean excursion peaks at a sea-level lowstand that produced the Sauk II-Sauk III sequence boundary on the North American craton. In this study, this excursion is documented for the first time in the northern U.S. Appalachians in poorly exposed limestone debris flow and olistolith deposits …
Spatial Variation In Sea Urchins, Fish Predators, And Bioerosion Rates On Coral Reefs Of Belize, Jocelyn Brown-Saracino, Paulette Peckol, H. Allen Curran, Martha L. Robbart
Spatial Variation In Sea Urchins, Fish Predators, And Bioerosion Rates On Coral Reefs Of Belize, Jocelyn Brown-Saracino, Paulette Peckol, H. Allen Curran, Martha L. Robbart
Biological Sciences: Faculty Publications
Although sea urchins are critical for controlling macroalgae on heavily fished coral reefs, high densities threaten reefs, as urchins are also prodigous bioeroders. This study examined urchin population characteristics, bioerosion rates, their fish predators (Labridae), and potential competitors (Scaridae) on unprotected reefs and a reef within a marine protected area (MPA) in the lagoonal regions off Belize. Urchin density (<1 >m-2) and bioerosion rates (∼0.2 kg CaCO3m-2year-1) were lowest and members of the Labridae were the highest (∼20 fish 200 m-3) within the MPA, while several unprotected reefs had higher (∼18-40 m-2) urchin densities, lower Labridae abundances (1-3 fish 200 …
Ichnofacies, Ichnocoenoses, And Ichnofabrics Of Quaternary Shallow-Marine To Dunal Tropical Carbonates: A Model And Implications, H. Allen Curran
Ichnofacies, Ichnocoenoses, And Ichnofabrics Of Quaternary Shallow-Marine To Dunal Tropical Carbonates: A Model And Implications, H. Allen Curran
Geosciences: Faculty Publications
A model of five ichnocoenoses within the Skolithos and Psilonichnus ichnofacies characterizes the modern, Holocene, and Pleistocene coastal-carbonate depositional environments and limestones of the Bahamas, as well as the Miami Limestone of south Florida. The subtidal to intertidal ichnocosnoses of the Skolithos ichnofacies are dominated by trace-making activities and trace fossils of callianassid shrimp, which can create distinctive and maximum ichnofabrics. Fossil Upogebia vasquezi burrows found in intertidal calcarenites and burrows of the trace fossil Psilonichnus upsilon, most common in beach backshore beds, have excellent potential as stratigraphic markers and can be used as indicators of past sea-level positions. …
Paleoenvironmental Reconstruction Of The Middle Eocene Trieste-Pazin Basin (Croatia) From Benthic Foraminiferal Assemblages, Sanja ŽIvkovic, Bosiljka Glumac
Paleoenvironmental Reconstruction Of The Middle Eocene Trieste-Pazin Basin (Croatia) From Benthic Foraminiferal Assemblages, Sanja ŽIvkovic, Bosiljka Glumac
Geosciences: Faculty Publications
Foraminiferal assemblages from four stratigraphic sections of the Trieste-Pazin basin in central Istria, Croatia (southwestern Tethyan realm) were investigated to reconstruct paleoenvironmental conditions and to determine the age of these deposits. The following five Middle Eocene planktonic foraminiferal zones were identified from the range and frequency of foraminiferal species: Globigerinatheka kugleri/Morozovella aragonensis Zone (E9), Acarinina topilensis Zone (E10), Morozovelloides lehneri Zone (E11), Orbulinoides beckmanni Zone (E12), and Morozovelloides crassatus Zone (E13). A data set of benthic foraminifera relative frequency has been subjected to R- and Q-mode cluster analyses to demonstrate the linkage between taxa distribution and paleoenvironmental gradients. Benthic foraminiferal …
Ichnogenic Porosity, High-Frequency Cyclostratigraphy, And Groundwater Flow In The Karst Biscayne Aquifer, Se Florida, Usa, Kevin Cunningham, H. Allen Curran
Ichnogenic Porosity, High-Frequency Cyclostratigraphy, And Groundwater Flow In The Karst Biscayne Aquifer, Se Florida, Usa, Kevin Cunningham, H. Allen Curran
Geosciences: Faculty Publications
No abstract provided.
Paleosalinity History Of Middle Holocene Lagoonal And Lacustrine Deposits In The Enriquillo Valley, Dominican Republic Based On Pore Morphometrics And Isotope Geochemistry Of Ostracoda, Pamela Medley, Neil E. Tibert, William P. Patterson, H. Allen Curran, Lisa Greer, Jean-Paul Colin
Paleosalinity History Of Middle Holocene Lagoonal And Lacustrine Deposits In The Enriquillo Valley, Dominican Republic Based On Pore Morphometrics And Isotope Geochemistry Of Ostracoda, Pamela Medley, Neil E. Tibert, William P. Patterson, H. Allen Curran, Lisa Greer, Jean-Paul Colin
Geosciences: Faculty Publications
The southwestern region of the Dominican Republic (Enriquillo Valley) contains exceptionally well-preserved, relict marine and saline lake deposits of mid-Holocne age. Abundant euryhaline ostracodes found in this deposit include Cyprideis salebrosa, C. mexicana, C. similis, and C. edentata. Morphometric and geochemical analyses performed on Cyprideis spp. provide high δ18O and δ13C values that are coincident with relative abundances of irregularly shaped pores that permeate the ostracode carapace. We recognize three stratigraphic intervals with distinct ostracode pore shape and stable isotope trends: (I) a 4.5-5.0m interval that contains ostracodes with highly irregular shaped pores (multiradiate) and …
Seasonal Variation In The Stable Isotopic Composition Of Precipitation In The Tropical Montane Forests Of Monteverde, Costa Rica, Amy L. Rhodes, Andrew J. Guswa, Silvia E. Newell
Seasonal Variation In The Stable Isotopic Composition Of Precipitation In The Tropical Montane Forests Of Monteverde, Costa Rica, Amy L. Rhodes, Andrew J. Guswa, Silvia E. Newell
Engineering: Faculty Publications
Climate and land use change may diminish orographic clouds over tropical montane forests, stressing biota and water resources during dry seasons. From 2003 to 2005 we measured the stable isotopic composition of precipitation and throughfall in Monteverde, Costa Rica, to distinguish convective, wet season rainfall associated with the Intertropical Convergence Zone (ITCZ) from dry season, orographic rain produced by northeasterly trade winds. While event-to-event fluctuations of δ18O and δ2H are high, monthly samples reveal a seasonal signal that may be used to trace water through the hydrologic cycle. Deuterium excess indicates that water evaporated from land is an important flux …
Seasonal Sediment Transport And Unusually Large Spit Development At Sandy Point, San Salvador, Bahamas, Vincent J. Voegeli, Alicia L. Simonti, H. Allen Curran
Seasonal Sediment Transport And Unusually Large Spit Development At Sandy Point, San Salvador, Bahamas, Vincent J. Voegeli, Alicia L. Simonti, 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
Geology Of Cat Island, Bahamas: A Field Trip Guide, John E. Mylroie, H. Allen Curran, Deborah Freile, James L. Carew, Neil E. Sealey, Vincent J. Voegeli
Geology Of Cat Island, Bahamas: A Field Trip Guide, John E. Mylroie, H. Allen Curran, Deborah Freile, James L. Carew, Neil E. Sealey, Vincent J. Voegeli
Geosciences: Faculty Publications
See other Smith authored Field Trip Guides of Gerace Research Centre.
Pervasive Cracking Of The Northern Chilean Coastal Cordillera: New Evidence For Forearc Extension, John P. Loveless, Gregory D. Hoke, Richard W. Allmendinger, Gabriel González, Bryan L. Isacks, Daniel A. Carrizo
Pervasive Cracking Of The Northern Chilean Coastal Cordillera: New Evidence For Forearc Extension, John P. Loveless, Gregory D. Hoke, Richard W. Allmendinger, Gabriel González, Bryan L. Isacks, Daniel A. Carrizo
Geosciences: Faculty Publications
Despite convergence across the strongly coupled seismogenic interface between the South American and Nazca plates, the dominant neotectonic signature in the forearc of northern Chile is arc-normal extension. We have used 1 m resolution IKONOS satellite imagery to map nearly 37,000 cracks over an area of 500 km2 near the Salar Grande (21°S). These features, which are best preserved in a ubiquitous gypcrete surface layer, have both nontectonic and tectonic origins. However, their strong preferred orientation perpendicular to the plate convergence vector suggests that the majority owe their formation to approximate east-west extension associated with plate boundary processes such as …
Coral Reef Ed-Ventures: An Environmental Education Program For School Children In San Pedro, Belize, H. Allen Curran, Susan Etheredge, Elizabeth Callaghan, Paulette M. Peckol
Coral Reef Ed-Ventures: An Environmental Education Program For School Children In San Pedro, Belize, H. Allen Curran, Susan Etheredge, Elizabeth Callaghan, Paulette M. Peckol
Geosciences: Faculty Publications
No abstract provided.
Evidence For Marine Influence On A Low-Gradient Coastal Plain: Ichnology And Invertebrate Paleontology Of The Lower Tongue River Member (Fort Union Formation, Middle Paleocene), Western Williston Basin, U.S.A., Edward S. Belt, Neil E. Tibert, H. Allen Curran, John A. Diemer, Joseph H. Hartman, Timothy J. Kroeger, David M. Harwood
Evidence For Marine Influence On A Low-Gradient Coastal Plain: Ichnology And Invertebrate Paleontology Of The Lower Tongue River Member (Fort Union Formation, Middle Paleocene), Western Williston Basin, U.S.A., Edward S. Belt, Neil E. Tibert, H. Allen Curran, John A. Diemer, Joseph H. Hartman, Timothy J. Kroeger, David M. Harwood
Geosciences: Faculty Publications
The Paleocene Tongue River Member of the Fort Union Formation contains trace-fossil associations indicative of marine influence in otherwise freshwater facies. The identified ichnogenera include: Arenicolites, Diplocraterion, Monocraterion, Ophiomorpha, Rhizocorallium, Skolithos linearis, Teichichnus, Thalassinoides, and one form of uncertain affinity. Two species of the marine diatom Coscinodiscus occur a few meters above the base of the member. The burrows occur in at least five discrete, thin, rippled, fine-grained sandstone beds within the lower 85 m of the member west of the Cedar Creek anticline (CCA) in the Signal Butte, Terry Badlands, and Pine Hills areas. Two discrete burrowed beds …
A Memorial To D. Craig Edwards (1939-2004), H. Allen Curran, Hilary Edwards Lithgow
A Memorial To D. Craig Edwards (1939-2004), H. Allen Curran, Hilary Edwards Lithgow
Geosciences: Faculty Publications
No abstract provided.
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
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 …
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
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 …
Marine Anthropogenic Debris Surveys On Hanna Bay And East Beaches, San Salvador Island, Bahamas, 1998–2004, Virginia White, H. Allen Curran
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
The Cape Ann Plutonic Suite: A Field Trip For Petrology Classes, John B. Brady, John T. Cheney
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 …
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
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 …
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
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 …
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
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 …
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
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
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
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.
Aragonite Pseudomorphs In High Pressure Marbles Of Syros, Greece, John B. Brady, Michelle J. Markley, John C. Schumacher, John T. Cheney, Grace A. Bianciardi
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 …