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Articles 31 - 60 of 77
Full-Text Articles in Geology
A Detailed Pb Isotopic Study Of Crustal Contamination Assimilation : The Edgecumbe Volcanic Field, Se Alaska, James Myers, A. K. Sinha
A Detailed Pb Isotopic Study Of Crustal Contamination Assimilation : The Edgecumbe Volcanic Field, Se Alaska, James Myers, A. K. Sinha
James Myers
To better understand the process of crustal contamination/assimilation, 23 Pb isotopic compositions and 12 concentrations have been measured on lavas and basement rocks from the Edgecumbe volcanic field, SE Alaska. Measured isotopic ratios have the following ranges: 206Pb204Pb = 18.477–19.161; 207Pb204Pb = 15.562–15.679; 208Pb204Pb = 38.17–38.85. While the data form well-constrained linear arrays on Pb-Pb diagrams, no simple correlation exists with major element composition. Basaltic lavas (≤ 51 wt% SiO2) are characterized by two isotopic groups. The olivine basalt (≤ 48% SiO2) is more radiogenic than the plagioclase basalt (48–51%) which also shows more heterogeneity. In the silica range 52–55%, …
U-Pb Discordance In Archean Detrital Quartzites, Central Wyoming: Implications For Pb Loss Mechanisms, Carol Frost, C. M. Allen, Susan Swapp, B R. Frost
U-Pb Discordance In Archean Detrital Quartzites, Central Wyoming: Implications For Pb Loss Mechanisms, Carol Frost, C. M. Allen, Susan Swapp, B R. Frost
B R Frost
Meeting abstract for "U-Pb Discordance in Archean Detrital Quartzites, Central Wyoming: Implications for Pb Loss Mechanisms," June 2010.
Transitory Brucite And The Chemistry And Mineralogy Of Serpentinite, J. S. Beard, B R. Frost, W. Bach
Transitory Brucite And The Chemistry And Mineralogy Of Serpentinite, J. S. Beard, B R. Frost, W. Bach
B R Frost
Meeting abstract for "Transitory Brucite and the Chemistry and Mineralogy of Serpentinite."
2.685-2.671 Ga Himalayan-Type Orogeny In The Northern Teton Range, Wyoming, Usa, B R. Frost, Susan Swapp, Carol Frost
2.685-2.671 Ga Himalayan-Type Orogeny In The Northern Teton Range, Wyoming, Usa, B R. Frost, Susan Swapp, Carol Frost
B R Frost
Meeting abstract for “2.685-2.671 Ga Himalayan-Type Orogeny in the Northern Teton Range, Wyoming, USA,” June 2009.
Functional Characterization Of C-Type Cytochromes From Iron-Respiring Bacteria, T. S. Magnuson, M. W. Swenson, Pj. S. Colberg, Carrick Eggleston
Functional Characterization Of C-Type Cytochromes From Iron-Respiring Bacteria, T. S. Magnuson, M. W. Swenson, Pj. S. Colberg, Carrick Eggleston
Carrick M Eggleston
Meeting Abstract for "Functional Characterization of C-Type Cytochromes from Iron-Respiring Bacteria."
Strain Localization Along The Atlantis Bank Oceanic Detachment Fault System, Southwest Indian Ridge, E. A. Miranda, Barbara John
Strain Localization Along The Atlantis Bank Oceanic Detachment Fault System, Southwest Indian Ridge, E. A. Miranda, Barbara John
Barbara John
Microstructural observations and mineral thermometry from in situ samples collected from the Atlantis Bank oceanic core complex (SW Indian Ridge) indicate that detachment faulting was initiated under hypersolidus conditions in the ductile regime and continued through subgreenschist temperatures through the ductile, semibrittle, and brittle regimes as strain localized along the exposed, now subhorizontal fault surface. Ductile, semibrittle, and brittle fabrics are developed within dominantly gabbroic rocks. Footwall rocks exhibit crystal plastic fabrics distributed over a structural thickness up to 400 m below the denuded fault surface exposed at the seafloor, whereas semibrittle and brittle fabrics are concentrated in the 80 …
Microbial Fuel Cell Study Of The Role Of Omca And Mtrc In Electron Transfer From Shewanella Oneidensis To Oxide Electrodes, R. B. Jani, Pj. S. Colberg, Carrick Eggleston, L. Shi, C. J. Reardon
Microbial Fuel Cell Study Of The Role Of Omca And Mtrc In Electron Transfer From Shewanella Oneidensis To Oxide Electrodes, R. B. Jani, Pj. S. Colberg, Carrick Eggleston, L. Shi, C. J. Reardon
Carrick M Eggleston
Meeting abstract of “Microbial Fuel Cell Study of the Role of OMCA and MTRC in Electron Transfer from Shewanella Oneidensis to Oxide Electrodes,” 2010, Earth, Energy, and the Environment.
Preservation Of Fe Isotope Compositions Of Iron Formation During Contact Metamorphism, Carol Frost, F. Von Blanckenburg, R. Schoenberg, B R. Frost, Susan Swapp
Preservation Of Fe Isotope Compositions Of Iron Formation During Contact Metamorphism, Carol Frost, F. Von Blanckenburg, R. Schoenberg, B R. Frost, Susan Swapp
B R Frost
Meeting abstract for “Preservation of Fe Isotope Compositions of Iron Formation During Contact Metamorphism,” May 2005.
Cooling History Of Atlantis Bank Oceanic Core Complex: Evidence For Hydrothermal Activity 2.6 Ma Off Axis, J. J. Schwartz, Barbara John, Michael Cheadle, P. W. Reiners, A. G. Baines
Cooling History Of Atlantis Bank Oceanic Core Complex: Evidence For Hydrothermal Activity 2.6 Ma Off Axis, J. J. Schwartz, Barbara John, Michael Cheadle, P. W. Reiners, A. G. Baines
Barbara John
We report 26 (U-Th)/He zircon ages from Atlantis Bank, Southwest Indian Ridge, which constrain time scales and rates of lower crustal cooling in ultraslow spreading oceanic crust in this setting. Samples from the detachment fault surface indicate that denuded oceanic crust cooled rapidly (< 1 Ma), yielding cooling rates > 1200 degrees C/Ma, consistent with existing models for the cooling of oceanic crust. (U-Th)/He zircon ages from samples collected along N-S and E-W trending faults scarps record young ages inconsistent with standard cooling models for lower oceanic crust. These samples have a mean (U-Th)/He zircon age 2.6 Ma younger than their corresponding igneous crystallization ages and …
Evolution Of The Southwest Indian Ridge From 55 Degrees 45 ' E To 62 Degrees E: Changes In Plate-Boundary Geometry Since 26 Ma, A. G. Baines, Michael Cheadle, H.J.B. Dick, A. H. Scheirer, Barbara John, N. J. Kusznir, T. Matsumoto
Evolution Of The Southwest Indian Ridge From 55 Degrees 45 ' E To 62 Degrees E: Changes In Plate-Boundary Geometry Since 26 Ma, A. G. Baines, Michael Cheadle, H.J.B. Dick, A. H. Scheirer, Barbara John, N. J. Kusznir, T. Matsumoto
Barbara John
[1] From 55 degrees 45'E to 58 degrees 45'E and from 60 degrees 30'E to 62 degrees 00'E, the ultraslow-spreading Southwest Indian Ridge (SWIR) consists of magmatic spreading segments separated by oblique amagmatic spreading segments, transform faults, and nontransform discontinuities. Off-axis magnetic and multibeam bathymetric data permit investigation of the evolution of this part of the SWIR. Individual magmatic segments show varying magnitudes and directions of asymmetric spreading, which requires that the shape of the plate boundary has changed significantly over time. In particular, since 26 Ma the Atlantis II transform fault grew by 90 km to reach 199 km, …
A Natural Analogue In Southwest Wyoming For Geologic Co-Sequestration Of Carbon & Sulfur, John Kaszuba, A. Navarre-Sitchler, G. Thyne, C. Chopping
A Natural Analogue In Southwest Wyoming For Geologic Co-Sequestration Of Carbon & Sulfur, John Kaszuba, A. Navarre-Sitchler, G. Thyne, C. Chopping
John Kaszuba
Meeting abstract for “A Natural Analogue in Southwest Wyoming for Geologic Co-Sequestration of Carbon & Sulfur,” June 2010.
The Magnetic-Properties Of Metaperidotitic Rocks As A Function Of Metamorphic Grade : Implications For Crustal Magnetic-Anomalies, P. N. Shive, B R. Frost, A. Peretti
The Magnetic-Properties Of Metaperidotitic Rocks As A Function Of Metamorphic Grade : Implications For Crustal Magnetic-Anomalies, P. N. Shive, B R. Frost, A. Peretti
B R Frost
Seventeen samples from the Malenco serpentinite in the Swiss Alps, representing systematic prograde metamorphic conditions from prehnite-pumpellyite to upper amphibolite, are moderately to strongly magnetic (average susceptibility of 6.61 × 10−2 SI units) due predominantly to the presence of a magnetite-rich spinel. Some greenschist facies samples contain the metal alloy awaruite (Ni3Fe); these contain in addition much greater amounts of magnetite. Small amounts of pyrrhotite in about half the samples complete the contributions to the total magnetization. Susceptibilities generally decrease with increasing metamorphic grade because of the production of increasing amounts of chromerich spinel which dilutes the magnetite component. These …
Synthesis And Photocatalytic Properties Of Nanocrystalline Hematite Films: Comparison To Natural Hematite Crystals, Aj. A. Shankle, Carrick Eggleston, J. Ackerman, C. J. Borman
Synthesis And Photocatalytic Properties Of Nanocrystalline Hematite Films: Comparison To Natural Hematite Crystals, Aj. A. Shankle, Carrick Eggleston, J. Ackerman, C. J. Borman
Carrick M Eggleston
Meeting abstract for "Synthesis and Photocatalytic Properties of Nanocrystalline Hematite Films: Comparison to Natural Hematite Crystals."
Relative Stability And Significance Of Dawsonite And Aluminum Minerals In Geologic Carbon Sequestration, John Kaszuba, H. S. Viswanathan, J. W. Carey
Relative Stability And Significance Of Dawsonite And Aluminum Minerals In Geologic Carbon Sequestration, John Kaszuba, H. S. Viswanathan, J. W. Carey
John Kaszuba
Computer simulations predict dawsonite, NaAlCO(3)(OH)(2), will provide long-term mineral sequestration of anthropogenic CO(2) whereas dawsonite rarely occurs in nature or in laboratory experiments that emulate a carbon repository. Resolving this discrepancy is important to determining the significance of dawsonite mineralization to the long-term security of geologic carbon sequestration. This study is an equilibrium-based experimental and modeling evaluation of underlying causes for inconsistencies between predicted and observed dawsonite stability. Using established hydrothermal methods, 0.05 molal NaHCO(3) aqueous solution and synthetic dawsonite were reacted for 18.7 days (449.2 hours) at 50 degrees C, 20 MPa. Temperature was increased to 75 degrees C …
Drilling Constraints On Lithospheric Accretion And Evolution At Atlantis Massif, Mid-Atlantic Ridge 30 Degrees N, D. K. Blackman, B. Ildefonse, Barbara John, Y. Ohara, D. J. Miller, N. Abe, M. Abratis, E. S. Andal, M. Andreani, S. Awaji, J. S. Beard, D. Brunelli, A. B. Charney, D. M. Christie, J. Collins, A. G. Delacour, H. Delius, M. Drouin, F. Einaudi, J. Escartin, B. R. Frost, G. Fruh-Green, P. B. Fryer, J. S. Gee, M. Godard, C. B. Grimes, A. Halfpenny, H. E. Hansen, A. C. Harris, A. Tamura, N. W. Hayman, E. Hellebrand, T. Hirose, J. G. Hirth, S. Ishimaru, K.T. M. Johnson, G. D. Karner, M. Linek, C. J. Macleod, J. Maeda, O. U. Mason, A. M. Mccaig, K. Michibayashi, A. Morris, T. Nakagawa, T. Nozaka, M. Rosner, R. C. Searle, G. Suhr, M. Tominaga, A. Vonder Handt, T. Yamasaki, X Zhao
Drilling Constraints On Lithospheric Accretion And Evolution At Atlantis Massif, Mid-Atlantic Ridge 30 Degrees N, D. K. Blackman, B. Ildefonse, Barbara John, Y. Ohara, D. J. Miller, N. Abe, M. Abratis, E. S. Andal, M. Andreani, S. Awaji, J. S. Beard, D. Brunelli, A. B. Charney, D. M. Christie, J. Collins, A. G. Delacour, H. Delius, M. Drouin, F. Einaudi, J. Escartin, B. R. Frost, G. Fruh-Green, P. B. Fryer, J. S. Gee, M. Godard, C. B. Grimes, A. Halfpenny, H. E. Hansen, A. C. Harris, A. Tamura, N. W. Hayman, E. Hellebrand, T. Hirose, J. G. Hirth, S. Ishimaru, K.T. M. Johnson, G. D. Karner, M. Linek, C. J. Macleod, J. Maeda, O. U. Mason, A. M. Mccaig, K. Michibayashi, A. Morris, T. Nakagawa, T. Nozaka, M. Rosner, R. C. Searle, G. Suhr, M. Tominaga, A. Vonder Handt, T. Yamasaki, X Zhao
B R Frost
Expeditions 304 and 305 of the Integrated Ocean Drilling Program cored and logged a 1.4 km section of the domal core of Atlantis Massif. Postdrilling research results summarized here constrain the structure and lithology of the Central Dome of this oceanic core complex. The dominantly gabbroic sequence recovered contrasts with predrilling predictions; application of the ground truth in subsequent geophysical processing has produced self-consistent models for the Central Dome. The presence of many thin interfingered petrologic units indicates that the intrusions forming the domal core were emplaced over a minimum of 100-220 kyr, and not as a single magma pulse. …
Oxygen Isotopic Ratio Of Ocean Zircon, C. Grimes, T. Ushikubo, Barbara John, J. W. Valley
Oxygen Isotopic Ratio Of Ocean Zircon, C. Grimes, T. Ushikubo, Barbara John, J. W. Valley
Barbara John
Meeting abstract for “Oxygen Isotopic Ratio of Ocean Zircon,” June 2009.
Interaction Of Redox Metalloproteins With Hematite Surfaces, N. Khare, Carrick Eggleston, Pj. S. Colberg
Interaction Of Redox Metalloproteins With Hematite Surfaces, N. Khare, Carrick Eggleston, Pj. S. Colberg
Carrick M Eggleston
Meeting Abstract for “Interaction of Redox Metalloproteins with Hematite Surfaces,” Plenary Day Lectures at “A Celebration of Geochemistry,” Copenhagen.
A-Type Granites And Related Rocks Through Time, R. Dall'agnol, Carol Frost, O. T. Ramo
A-Type Granites And Related Rocks Through Time, R. Dall'agnol, Carol Frost, O. T. Ramo
Carol Frost
Meeting abstract for “A-Type Granites and Related Rocks Through Time,” May 2005.
Response To Comment On "Point Of Zero Charge Of A Corundum-Water Interface Probed With Optical Second Harmonic Generation (Shg) And Atomic Force Microscopy (Afm): New Approaches To Oxide Surface Charge", A. G. Stack, S. R. Higgins, Carrick Eggleston
Response To Comment On "Point Of Zero Charge Of A Corundum-Water Interface Probed With Optical Second Harmonic Generation (Shg) And Atomic Force Microscopy (Afm): New Approaches To Oxide Surface Charge", A. G. Stack, S. R. Higgins, Carrick Eggleston
Carrick M Eggleston
The purpose of this response is to address several misrepresentations of Stack et al. (2001) and its intent in the preceding Comment. At issue, primarily, is our observed point of zero salt effect (p.z.s.e.) of a single crystal face of corundum using optical second harmonic generation (SHG) at a pH (∼5) much lower than the accepted value (in the 8–9 range) of the pristine p.z.c. of alumina powders. Dr. Kosmulski’s main claim is that our anomalous observation is the result of surface contamination.
Protracted Construction Of Gabbroic Crust At A Slow Spreading Ridge: Constraints From (206)Pb/(238)U Zircon Ages From Atlantis Massif And Iodp Hole U1309d (30 Degrees N, Mar), C. B. Grimes, Barbara John, Michael Cheadle, J. L. Wooden
Protracted Construction Of Gabbroic Crust At A Slow Spreading Ridge: Constraints From (206)Pb/(238)U Zircon Ages From Atlantis Massif And Iodp Hole U1309d (30 Degrees N, Mar), C. B. Grimes, Barbara John, Michael Cheadle, J. L. Wooden
Barbara John
Sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon ages of 24 samples from oceanic crust recovered in Integrated Ocean Drilling Program (IODP) Hole U1309D and from the surface of Atlantis Massif, Mid-Atlantic Ridge (MAR) (30 degrees N) document a protracted history of accretion in the footwall to an oceanic detachment fault. Ages for 18 samples of evolved Fe-Ti oxide gabbro and felsic dikes collected 40-1415 m below seafloor in U1309D yield a weighted mean of 1.20 +/- 0.03 Ma (mean square of weighted deviates = 7.1). However, the ages range from 1.08 +/- 0.07 Ma and 1.28 +/- 0.05 Ma indicating …
Intrinsic Silica Metasomatism During Serpentinization, F. Klein, W. Bach, N. Jons, T. Nccollom, B R. Frost
Intrinsic Silica Metasomatism During Serpentinization, F. Klein, W. Bach, N. Jons, T. Nccollom, B R. Frost
B R Frost
Meeting Abstract for "Intrinsic Silica Metasomatism During Serpentinization."
Redox-Linked Conformation Change Observed For Adsorbed Metal-Reducing Bacterial Cytochromes, L. V. Sycheva, Carrick Eggleston, Pj. S. Colberg, T. S. Magnuson, L. Shi
Redox-Linked Conformation Change Observed For Adsorbed Metal-Reducing Bacterial Cytochromes, L. V. Sycheva, Carrick Eggleston, Pj. S. Colberg, T. S. Magnuson, L. Shi
Carrick M Eggleston
Meeting abstract of “Redox-Linked Conformation Change Observed for Adsorbed Metal-Reducing Bacterial Cytochromes,” 2010, Earth, Energy, and the Environment.
Crust And Upper Mantle Velocity Structure Of The Yellowstone Hot Spot And Surroundings, D. L. Schutt, Ken Dueker, H. Yuan
Crust And Upper Mantle Velocity Structure Of The Yellowstone Hot Spot And Surroundings, D. L. Schutt, Ken Dueker, H. Yuan
Ken Dueker
The Yellowstone hot spot has recently been shown to be a plume that extends into the transition zone. At roughly 60-120 km depth, the plume material rising beneath Yellowstone Park is sheared SW by North America Plate motion, producing a profound low velocity layer emplaced beneath the thin lithosphere. To constrain the absolute seismic velocity of the plate-sheared plume layer, fundamental mode Rayleigh wave observations have been inverted for phase velocity using the two plane wave technique. The resulting phase velocity models are inverted with Moho-converted P to S arrival times to better constrain crustal thickness and absolute S wave …
A Mesoarchean Rifted Continental Margin In The Wyoming Province: Evidence For Supercontinent Breakup, Susan Swapp, Carol Frost, B R. Frost
A Mesoarchean Rifted Continental Margin In The Wyoming Province: Evidence For Supercontinent Breakup, Susan Swapp, Carol Frost, B R. Frost
B R Frost
Meeting abstract for "A Mesoarchean Rifted Continental Margin in the Wyoming Province: Evidence for Supercontinent Breakup."
Carbonate Assimilation In The Alkaline Hortavaer Igneous Complex, Norway, C. G. Barnes, Y. Li, M. Barnes, L. Mccullock, Carol Frost, T. Prestvik, C. Allen
Carbonate Assimilation In The Alkaline Hortavaer Igneous Complex, Norway, C. G. Barnes, Y. Li, M. Barnes, L. Mccullock, Carol Frost, T. Prestvik, C. Allen
Carol Frost
Meeting abstract for “Carbonate Assimilation in the Alkaline Hortavaer Igneous Complex, Norway,” Aug-Sept 2006.
Electrochemical Interaction Of Shewanella Oneidensis Mr-1 And Its Outer Membrane Cytochromes Omca And Mtrc With Hematite Electrodes, L. A. Meitl, Carrick Eggleston, P.J.S. Colberg, N. Khare, C. L. Reardon, L. Shi
Electrochemical Interaction Of Shewanella Oneidensis Mr-1 And Its Outer Membrane Cytochromes Omca And Mtrc With Hematite Electrodes, L. A. Meitl, Carrick Eggleston, P.J.S. Colberg, N. Khare, C. L. Reardon, L. Shi
Carrick M Eggleston
Bacterial metal reduction is an important biogeochemical process in anaerobic environments. An understanding of electron transfer pathways from dissimilatory metal-reducing bacteria (DMRB) to solid phase metal (hydr)oxides is important for understanding metal redox cycling in soils and sediments, for utilizing DMRB in bioremedation, and for developing technologies such as microbial fuel cells. Here we hypothesize that the outer membrane cytochromes OmcA and MtrC from Shewanella oneidensis MR-1 are the only terminal reductases capable of direct electron transfer to a hematite working electrode. Cyclic voltammetry (CV) was used to study electron transfer between hematite electrodes and protein films, S. oneidensis MR-1 …
Crustal Structure And Thickness Along The Yellowstone Hot Spot Track: Evidence For Lower Crustal Outflow From Beneath The Eastern Snake River Plain, H. Yuan, Ken Dueker, J. Stachnik
Crustal Structure And Thickness Along The Yellowstone Hot Spot Track: Evidence For Lower Crustal Outflow From Beneath The Eastern Snake River Plain, H. Yuan, Ken Dueker, J. Stachnik
Ken Dueker
Receiver functions from seismic stations about the Yellowstone hot spot track are migrated to depth using a Vp/Vs map constructed from stacking of the direct and free surface Moho reverberations (i.e., H-K analysis) and a shear velocity tomogram constructed from surface wave measurements. The thickest crust (48-54 km) resides in the Wyoming province beneath the sampled Laramide age blocks, and the thinnest crust (32-37 km) resides in the Montana Basin and Range province. The eastern Snake River Plain (ESRP) crust is thickest (47 km) at its NE end beneath the young calderas and thinnest (40 km) at its SW end …
Direct Electrochemistry Of Cytochrome C On Oxide Electrodes, Carrick Eggleston, N. Khare, D. Lovelace
Direct Electrochemistry Of Cytochrome C On Oxide Electrodes, Carrick Eggleston, N. Khare, D. Lovelace
Carrick M Eggleston
Meeting abstract of “Direct Electrochemistry of Cytochrome C on Oxide Electrodes,” Interfacial Biogeochemical Processes.
Surface And Solution Structure Of Mitochondrial Cytochrome C, N. Khare, Carrick Eggleston, D. M. Lovelace
Surface And Solution Structure Of Mitochondrial Cytochrome C, N. Khare, Carrick Eggleston, D. M. Lovelace
Carrick M Eggleston
Meeting abstract for "Surface and Solution Structure of Mitochondrial Cytochrome C."
Interaction Of Cytochromes With Oxide Surfaces: Adsorption-Induced Conformation Change?, Carrick Eggleston, N. Khare, D. Lovelace
Interaction Of Cytochromes With Oxide Surfaces: Adsorption-Induced Conformation Change?, Carrick Eggleston, N. Khare, D. Lovelace
Carrick M Eggleston
Meeting abstract of “Interaction of Cytochromes with Oxide Surfaces: Adsorption-Induced Conformation Change?”, Mineral Surface Reactivity.