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Articles 1 - 16 of 16
Full-Text Articles in Physical Sciences and Mathematics
Solute Fluxes Through Restored Prairie And Intensively Managed Critical Zones In Nebraska And Iowa, Ashlee L. Dere, Andrew W. Miller, Amy M. Hemje, Sara K. Parcher, Courtney A. Capalli, E. Arthur Bettis Iii
Solute Fluxes Through Restored Prairie And Intensively Managed Critical Zones In Nebraska And Iowa, Ashlee L. Dere, Andrew W. Miller, Amy M. Hemje, Sara K. Parcher, Courtney A. Capalli, E. Arthur Bettis Iii
Geography and Geology Faculty Publications
Agricultural activities in the Midwestern United States have potentially altered geochemical fluxes within the critical zone (CZ) compared to native prairie systems that previously dominated the region. To quantify the impact of agricultural land use on soil and stream solute behavior, we are studying two watersheds in the region: Glacier Creek Preserve (GCP) in eastern Nebraska and the Intensively Managed Landscapes Critical Zone Observatory (IML-CZO) in eastern Iowa. Both watersheds were initially under agricultural land use for over 100 years, but part of each watershed was restored to prairie 20 – 50 years ago. Soils at both sites formed in …
Mineralogical Transformations And Soil Development In Shale Across A Latitudinal Climosequence, Ashlee L.D. Dere, Timothy S. White, Richard H. April, Susan L. Brantley
Mineralogical Transformations And Soil Development In Shale Across A Latitudinal Climosequence, Ashlee L.D. Dere, Timothy S. White, Richard H. April, Susan L. Brantley
Geography and Geology Faculty Publications
To investigate factors controlling soil formation, we established a climosequence as part of the Susquehanna-Shale Hills Critical Zone Observatory (SSHCZO) in central Pennsylvania, USA. Sites were located on organic matter-poor, iron-rich Silurian-aged shale in Wales, Pennsylvania, Virginia, Tennessee, Alabama, and Puerto Rico, although this last site is underlain by a younger shale. Across the climosequence, mean annual temperature (MAT) increases from 7 to 24°C and mean annual precipitation (MAP) ranges from 100 to 250 cm. Variations in soil characteristics along the climosequence, including depth, morphology, particle-size distribution, geochemistry, and bulk and clay mineralogy, were characterized to investigate the role of …
Designing A Suite Of Measurements To Understand The Critical Zone, Susan L. Brantley, Roman A. Dibiase, Tess A. Russo, Yuning Shi, Henry Lin, Kenneth J. Davis, Margot Kaye, Lillian Hill, Jason Kaye, David M. Eissenstat, Beth Hoagland, Ashlee L.D. Dere, Andrew L. Neal, Kristen M. Brubaker, Dan K. Arthur
Designing A Suite Of Measurements To Understand The Critical Zone, Susan L. Brantley, Roman A. Dibiase, Tess A. Russo, Yuning Shi, Henry Lin, Kenneth J. Davis, Margot Kaye, Lillian Hill, Jason Kaye, David M. Eissenstat, Beth Hoagland, Ashlee L.D. Dere, Andrew L. Neal, Kristen M. Brubaker, Dan K. Arthur
Geography and Geology Faculty Publications
Many scientists have begun to refer to the earth surface environment from the upper canopy to the depths of bedrock as the critical zone (CZ). Identification of the CZ as an integral object worthy of study implicitly posits that the study of the whole earth surface will provide benefits that do not arise when studying the individual parts. To study the CZ, however, requires prioritizing among the measurements that can be made – and we do not generally agree on the priorities. Currently, the Susquehanna Shale Hills Critical Zone Observatory (SSHCZO) is expanding from a small original focus area (0.08 …
Cone-In-Cone And Beef Mineralization Associated With Triassic Growth Basin Faulting And Shallow Shale Diagenesis, Edgeøya, Svalbard, Harmon D. Maher Jr., Kei Ogata, Alvar Braathen
Cone-In-Cone And Beef Mineralization Associated With Triassic Growth Basin Faulting And Shallow Shale Diagenesis, Edgeøya, Svalbard, Harmon D. Maher Jr., Kei Ogata, Alvar Braathen
Geography and Geology Faculty Publications
Cone-in-cone (CIC) and beef (BF) carbonate lenses ornament detachment zone faults underlying Triassic growth basins on Edgeøya. Field relationships place CIC and BF growth as during early diagenesis and a transition from hydroplastic to a later brittle-style of faulting that is marked by coarser calcite veining. Deformation is constrained to have occurred at<300 mdepth. Multiple models exist for CIC formation. For the Edgeøya example, textural analysis of thin-sections suggests that small tensile fractures and carbonate shell fragments nucleated development of calcite aggregates with CIC and BF morphology within unconsolidated to poorly consolidated sediment to form asymmetric antitaxial tensile aggregates subparallel to bedding and fault surfaces. The conical forms result from differential growth on stepped, cleavage-parallel faces of fibres facing host sediment, with preferential inclusion incorporation at inner corners. The preferred directions of calcite growth are attributed to local stresses and seepage flow associated with pore pressure gradients. Substantial framboidal pyrite in the sediments represents an early phase of microbially driven sulphate reduction, which may have induced calcite mineralization. The transition to brittle-style faulting was marked by development of deformation twins in CIC/BF fibres, and a transition to coarse, blocky calcite growth in relay arrays of steeply oriented microveins. This indicates local fault-related stresses substantially changed during shallow diagenesis and lithification, an evolution attributed to changing pore pressures, seepage forces and material moduli. Calcite mineralizations at Edgeøya track the very significant changes in mechanical properties and stress states that occur during synlithification deformation at very shallow crustal levels.
Natural And Anthropogenic Processes Contributing To Metal Enrichment In Surface Soils Of Central Pennsylvania, A. M.L. Kraepiel, Ashlee L.D. Dere, E. M. Herndon, Susan L. Brantley
Natural And Anthropogenic Processes Contributing To Metal Enrichment In Surface Soils Of Central Pennsylvania, A. M.L. Kraepiel, Ashlee L.D. Dere, E. M. Herndon, Susan L. Brantley
Geography and Geology Faculty Publications
Metals in soils may positively or negatively affect plants as well as soil micro-organisms and mesofauna, depending on their abundance and bioavailability. Atmospheric deposition and biological uplift commonly result in metal enrichment in surface soils, but the relative importance of these processes is not always resolved. Here, we used an integrated approach to study the cycling of phosphorus and a suite of metals from the soil to the canopy (and back) in a temperate watershed. The behavior of elements in these surface soils fell into three categories. First, Al, Fe, V, Co, and Cr showed little to no enrichment in …
Biotic Controls On Solute Distribution And Transport In Headwater Catchments, E. M. Herndon, Ashlee L.D. Dere, P. L. Sullivan, D. Norris, B. Reynolds, Susan L. Brantley
Biotic Controls On Solute Distribution And Transport In Headwater Catchments, E. M. Herndon, Ashlee L.D. Dere, P. L. Sullivan, D. Norris, B. Reynolds, Susan L. Brantley
Geography and Geology Faculty Publications
Solute concentrations in stream water vary with discharge in patterns that record complex feedbacks between hydrologic and biogeochemical processes. In a comparison of headwater catchments underlain by shale in Pennsylvania, USA (Shale Hills) 5 and Wales, UK (Plynlimon), dissimilar concentration-discharge behaviors are best explained by contrasting landscape distributions of soil solution chemistry – especially dissolved organic carbon (DOC) – that have been established by patterns of vegetation. Specifically, elements that are concentrated in organic-rich soils due to biotic cycling (Mn, Ca, K) or that form strong complexes with DOC (Fe, Al) are spatially heteroge- 10 neous in pore waters because …
Strata-Bound Vein Array In The Basal Pierre Shale, Lake Francis Case, South Dakota, U.S.A, Harmon D. Maher Jr., Sarah Ferguson, Ryan Korth, Justine Marshall, Laura Pickett
Strata-Bound Vein Array In The Basal Pierre Shale, Lake Francis Case, South Dakota, U.S.A, Harmon D. Maher Jr., Sarah Ferguson, Ryan Korth, Justine Marshall, Laura Pickett
Geography and Geology Faculty Publications
A distinctive strata-bound vein array occurs in the basal Pierre Shale exposed along the shores of Lake Francis Case, a reservoir on the Missouri River in south-central South Dakota. Typically 2–4 meters in thickness, the array consistently outcrops over a >50-km distance, a significant areal footprint. Ash layers define the upper and lower bounds of the vein array. Two, suborthogonal, preferred directions of vertical veins (northeast and southeast strike) define a regional pattern. By volume, vertical veins comprise 1–2% of the rock. Thinner, more discontinuous, and irregular horizontal veins also occur. Comparisons between array orientations and the joint/vein pattern in …
Growth Of Extensional Faults And Folds During Deposition Of An Evaporite-Dominated Half-Graben Basin; The Carboniferous Billefjorden Trough, Svalbard, Alvar Braathen, Karoline Bælum, Harmon Maher Jr., Simon J. Buckley
Growth Of Extensional Faults And Folds During Deposition Of An Evaporite-Dominated Half-Graben Basin; The Carboniferous Billefjorden Trough, Svalbard, Alvar Braathen, Karoline Bælum, Harmon Maher Jr., Simon J. Buckley
Geography and Geology Faculty Publications
Normal-sense movements along two major strands of the Billefjorden Fault Zone controlled sedimentation in the Carboniferous Billefjorden Trough. The Billefjorden Trough is a more than 2000 meters thick, west-dipping half-graben basin where accommodation was provided by combinations of extensional faulting and folding throughout the basin history. Whereas previous workers have interpreted several of these folds as due to Tertiary contraction, we argue that they developed during rifting, as extensional forced folds in the style described by other workers from rifts such as the Gulf of Suez. The present basin geometry indicates that accommodation was facilitated by a combination of fault …
Review Of Hard Road West: History And Geology Along The Gold Rush Trail By Keith Heyer Meldahl, Harmon D. Maher Jr.
Review Of Hard Road West: History And Geology Along The Gold Rush Trail By Keith Heyer Meldahl, Harmon D. Maher Jr.
Geography and Geology Faculty Publications
The dust jacket of Hard Road West promises familiar pleasures to John McPhee lovers, and so I picked the book up with great anticipation. McPhee’s works have greatly heightened the interest of writers and readers in the genre of creative nonfiction, and while for me, Keith Meldahl’s work does not quite reach McPhee’s stratospheric heights, for the right audience it is definitely a very good read.
Iron Ooid Beds Of The Carolinefjellet Formation, Spitsbergen, Norway, Jeremy Mutrux, Harmon D. Maher Jr., Robert Duncan Shuster
Iron Ooid Beds Of The Carolinefjellet Formation, Spitsbergen, Norway, Jeremy Mutrux, Harmon D. Maher Jr., Robert Duncan Shuster
Geography and Geology Faculty Publications
Iron ooid beds are unusual deposits that have been linked to greenhouse conditions and the transgressive flooding of shallow shelves, and which were globally prevalent during certain periods. Within the marine, Aptian-Albian, Carolinefjellet Formation of Spitsbergen, chamosite ooids have been found within distinctive sandstone beds at six localities, and at a consistent stratigraphic position within the basal Dalkjegla Member. Distinctive characteristics include the iron ooids themselves, a coarser grain size, intercalation with silty siderites, grading, cross-beds indicating offshore or longshore transport, and a lack of burrowing. The enclosing sands display planar and hummocky crossstratification and abundant oscillation ripple marks, and …
Review Of Lewis And Clark And The Geology Of The Great Plains And Lewis And Clark And The Geology Of Nebraska And Parts Of Adjacent States, Harmon D. Maher Jr.
Review Of Lewis And Clark And The Geology Of The Great Plains And Lewis And Clark And The Geology Of Nebraska And Parts Of Adjacent States, Harmon D. Maher Jr.
Geography and Geology Faculty Publications
When it comes to science in general, and the geology of the Great Plains in particular, there is arguably an imbalance between the wealth of material written for experts and the relative paucity written for the general public. These publications help correct that imbalance at a time when the various Lewis and Clark celebrations create an especially receptive and engaged audience.
Petrography Of Lower Cretaceous Sandstones On Spitsbergen, Harmon D. Maher Jr., Troy Hays, Robert Duncan Shuster, Jeremy Mutrux
Petrography Of Lower Cretaceous Sandstones On Spitsbergen, Harmon D. Maher Jr., Troy Hays, Robert Duncan Shuster, Jeremy Mutrux
Geography and Geology Faculty Publications
The sandstone petrography of sample suites from four sites spanning the Rurikfjellet (Hauterivian) to Carolinefjellet (Aptian–Albian) formations in central Spitsbergen was investigated. The sandstones show a distinct stepwise shift in composition from quartz arenites to sublitharenites and lithic arenites, typically within the upper part of the Helvetiafjellet Formation. This shift is related to the introduction of 10 - 25 % (grain %) plagioclase grains and volcanic lithics, and a notable increase in basement and sedimentary lithics. Quartz grain character also changes, and grain shapes become more varied. The shift is also associated with the transgressive arrival of marine sediments in …
Source Of The Northeastern Idaho Batholith: Isotopic Evidence For A Paleoproterozoic Terrane In The Northwestern U.S., Paul A. Mueller, Robert Duncan Shuster, K. A. D'Arcy, A. L. Heatherington, A. P. Nutman, I. S. Williams
Source Of The Northeastern Idaho Batholith: Isotopic Evidence For A Paleoproterozoic Terrane In The Northwestern U.S., Paul A. Mueller, Robert Duncan Shuster, K. A. D'Arcy, A. L. Heatherington, A. P. Nutman, I. S. Williams
Geography and Geology Faculty Publications
The northeastern portion of the Idaho batholith (NIB) intruded Proterozoic rocks of the Belt-Purcell supergroup between SO and 90 Ma. Whole-rock Sm-Nd isotopic analyses of batholithic rocks yield depleted mantle model ages (T oM) between 1. 72 and 1.93 Ga and values of eNd between -17. 7 and - 21.2, similar to associated metamorphic rocks and within the range for Belt-Purcell sedimentary rocks. Premagmatic zircons from one sample of the NIB were analyzed individually using the SHRIMP ion microprobe and yielded a single age population at 1.74 Ga. This apparently single-aged source contrasts with the range of ages reported for …
Strontium Isotope Stratigraphy And Age Estimates For The Leisey Shell Pit Faunas, Hillsborough County, Florida, Douglas S. Jones, Paul A. Mueller, Teresa Acosta, Robert Duncan Shuster
Strontium Isotope Stratigraphy And Age Estimates For The Leisey Shell Pit Faunas, Hillsborough County, Florida, Douglas S. Jones, Paul A. Mueller, Teresa Acosta, Robert Duncan Shuster
Geography and Geology Faculty Publications
The vertebrate fauna of the Leisey Shell Pit near Tampa Bay, Florida, represents one of the more significant lrvingtonian mammalian faunas of North America. The fossil vertebrates occur in thin bone beds bounded above and below by massive shell beds containing a rich invertebrate ( chiefly molluscan) fauna. Debate has arisen concerning the precise age of the faunas at Leisey. Although generally agreed to be Pleistocene, estimates based upon vertebrate biostratigraphy suggest a somewhat older age than do estimates based upon molluscan biostratigraphy. To help resolve this controvefliy, 87Sr/86Sr ratios were determined on molluscan shells throughout the …
U-Pb Studies Of Zircon Cores And Overgrowths, And Monazite: Implications For Age And Petrogenesis Of The Northeastern Idaho Batholith, M. E. Bickford, R. B. Chase, B. K. Nelson, Robert Duncan Shuster, E. C. Arruda
U-Pb Studies Of Zircon Cores And Overgrowths, And Monazite: Implications For Age And Petrogenesis Of The Northeastern Idaho Batholith, M. E. Bickford, R. B. Chase, B. K. Nelson, Robert Duncan Shuster, E. C. Arruda
Geography and Geology Faculty Publications
U/Pb isotopic studies of zircons, many containing xenocrystic cores with euhedral overgrowths, and monazite from igneous rocks and metasedimentary inclusions of the northeastern Idaho batholith yield linear arrays on concordia diagrams. We interpret these as mixing lines between an old component (cores) and a young component (overgrowths and zircons without cores). The lower intercept of such arrays with concordia may yield the minimum age of the rocks if the overgrowths and zircons without cores are discordant, or the crystallization age if they are concordant. Monazites yield apparently concordant ages either equal or less than the lower intercept zircon ages. The …
Progress On Rock Glacier Research, John F. Shroder Jr., John R. Giardino
Progress On Rock Glacier Research, John F. Shroder Jr., John R. Giardino
Geography and Geology Faculty Publications
This report is an account of research progress on rock glaciers of Afghanistan, Colorado, and Utah. Because of the preliminary nature of this work, some speculation is present; nevertheless, we think there is evidence for each major, new point expressed. The main thesis of our work is that rock glaciers are polygenetic and appear to be part of a continuum of similar landforms grading morphologically and, presumably, mechanically from one type to another type.