Reprocessing and enhanced interpretation of the initial COCORP Southern Appalachians traverse   总被引：1，自引：0，他引：1  

Frederick A. Cook  Kris Vasudevan 《Tectonophysics》2006,420(1-2):161

Reprocessing of the 1978–1980 COCORP Southern Appalachian seismic reflection data has produced improved images of structures related to the emplacement of the Blue Ridge–Inner Piedmont allochthon. The results enhance and extend the interpretation presented previously that the Blue Ridge and Inner Piedmont are allochthonous above a shallow, and shallow dipping, detachment that can be followed from outcrop at the Blue Ridge/Valley and Ridge transition to at least beneath the Carolina terrane. The continuity of reflections in the new images supports the interpretation that the southern Appalachian detachment is not rooted on the east side of the Inner Piedmont, but rather projects as a low-angle detachment (or zone of decoupling) to beneath the Coastal Plain. An implication of this geometry is that terranes, such as the Carolina terrane, between autochthonous North America and the Alleghanian suture beneath the Coastal Plain are detached, thin flakes.  相似文献   

Different morphology of Nuphar lutea in two contrasting aquatic environments and its effect on ecosystem engineering          下载免费PDF全文

Jonas Schoelynck  Kris Bal  Veerle Verschoren  Ellis Penning  Eric Struyf  Tjeerd Bouma  Dieter Meire  Patrick Meire  Stijn Temmerman 《地球表面变化过程与地形》2014,39(15):2100-2108

Aquatic plants (macrophytes) can have a large effect on river hydraulics and geomorphology. Though, the extent to how plant morphological plasticity actively influences these feedbacks has received little scientific attention. The nymphaeid macrophyte species Nuphar lutea (L.) Smith is characterized by a distinct leaf duality. Floating leaves shade most of the submerged leaves thereby limiting light penetration in the water. Despite their apparent negligible photosynthetic role, submerged leaves of N. lutea remain intact during summer and contribute a significant part to the total biomass. Our results indicate that the submerged leaves are crucial in plant–flow interactions and hence in the engineering potential of the plant, i.e. the capacity to locally reduce flow velocities and to promote sedimentation, including organic matter deposition. Plant individuals growing in running river water were compared to individuals from adjacent oxbow lake water. The number and size of submerged leaves were significantly higher for river standing individuals and the accumulated sediment contained significantly more organic matter, total nitrogen and total phosphorus, and was characterized by a lower carbon/nitrogen ratio and a finer grain size. We therefore argue that the submerged N. lutea canopy in rivers has the ability to create a high‐nutrient, low hydrodynamic environment, resembling the conditions found in oxbow lakes. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Imagineering Uneven Geographical Development in Central Florida          下载免费PDF全文

Kris Bezdecny 《Geographical review》2015,105(3):325-343

In an era when it is proclaimed that, through globalization, the world has become flat, the unevenness of economic and social development is often overlooked or suppressed. This case study explores the conditions of uneven geographical development in the urban space of central Florida. Focusing primarily on the Reedy Creek Improvement District (RCID), better known to much of the world as Walt Disney World, and on Celebration, the community developed by the Disney Corporation in the 1990s, the relationship between tourism, the defining economic sector in the region, and uneven geographical development is explored. This study shows that the theory of uneven geographical development applies well to a region that is heavily dependent upon the tourist sector for its economy, and thereby works to control the narrative of that space to continue attracting consumers.  相似文献   

The shapes of dark matter dominated dwarf spheroidal stellar density profiles     

Kris Sigurdson  Neil Turok 《Monthly notices of the Royal Astronomical Society》2002,336(1):151-154

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Expanding the SDI environment: comparing current spatial data infrastructure with emerging indoor location-based services     

David J. Coleman  Abbas Rajabifard  Kris W. Kolodziej 《International Journal of Digital Earth》2016,9(6):629-647

The authors compare key elements of the emerging field of Indoor Location-Based Services (Indoor LBS) to those currently found in spatial data infrastructure (SDI) programs. After a brief review of SDIs and Location-Based Services, the corresponding drivers, characteristics and emerging issues within the field of Indoor LBS are introduced and discussed. A comparative framework relates the two in terms of the criteria ‘People’, ‘Data', ‘Technologies', ‘Standards' and ‘Policies/Institutional Arrangements'. After highlighting key similarities and differences, the authors suggested three areas – definition of common framework datasets in Indoor LBS, more effective use of volunteered geographic information by SDI programs and development of appropriate privacy policies by both communities – that may benefit from sharing ‘lessons learned'.  相似文献   

The High Resolution Imaging Science Experiment (HiRISE) during MRO’s Primary Science Phase (PSP)     

Alfred S. McEwen  Maria E. Banks  Kris Becker  James W. Bergstrom  Edward Bortolini  Shane Byrne  Frank C. Chuang  Ingrid Daubar  Donald G. Deardorff  W. Alan Delamere  Colin M. Dundas  Yisrael Espinoza  Kathryn E. Fishbaugh  Paul E. Geissler  Jennifer L. Griffes  Virginia C. Gulick  Kenneth E. Herkenhoff  Windy L. Jaeger  Bob Kanefsky  Robert King  Kelly J. Kolb  Alexandra Lefort  Kevin W. Lewis  Sarah Mattson  Michael T. Mellon  Moses P. Milazzo  Tahirih Motazedian  Albert Ortiz  Joseph Plassmann  Patrick S. Russell  Mindi L. Searls  Steven W. Squyres  Nicolas Thomas  Livio L. Tornabene  Circe Verba  James J. Wray 《Icarus》2010,205(1):2-216

The High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO) acquired 8 terapixels of data in 9137 images of Mars between October 2006 and December 2008, covering ∼0.55% of the surface. Images are typically 5-6 km wide with 3-color coverage over the central 20% of the swath, and their scales usually range from 25 to 60 cm/pixel. Nine hundred and sixty stereo pairs were acquired and more than 50 digital terrain models (DTMs) completed; these data have led to some of the most significant science results. New methods to measure and correct distortions due to pointing jitter facilitate topographic and change-detection studies at sub-meter scales. Recent results address Noachian bedrock stratigraphy, fluvially deposited fans in craters and in or near Valles Marineris, groundwater flow in fractures and porous media, quasi-periodic layering in polar and non-polar deposits, tectonic history of west Candor Chasma, geometry of clay-rich deposits near and within Mawrth Vallis, dynamics of flood lavas in the Cerberus Palus region, evidence for pyroclastic deposits, columnar jointing in lava flows, recent collapse pits, evidence for water in well-preserved impact craters, newly discovered large rayed craters, and glacial and periglacial processes. Of particular interest are ongoing processes such as those driven by the wind, impact cratering, avalanches of dust and/or frost, relatively bright deposits on steep gullied slopes, and the dynamic seasonal processes over polar regions. HiRISE has acquired hundreds of large images of past, present and potential future landing sites and has contributed to scientific and engineering studies of those sites. Warming the focal-plane electronics prior to imaging has mitigated an instrument anomaly that produces bad data under cold operating conditions.  相似文献   

Pb isotopic constraints on the formation of the Dikulushi Cu–Pb–Zn–Ag mineralisation, Kundelungu Plateau (Democratic Republic of Congo)     

Maarten Haest  Jens Schneider  Christophe Cloquet  Kris Latruwe  Frank Vanhaecke  Philippe Muchez 《Mineralium Deposita》2010,45(4):393-410

Base metal–Ag mineralisation at Dikulushi and in other deposits on the Kundelungu Plateau (Democratic Republic of Congo) developed during two episodes. Subeconomic Cu–Pb–Zn–Fe polysulphide ores were generated during the Lufilian Orogeny (c. 520 Ma ago) in a set of E–W- and NE–SW-oriented faults. Their lead has a relatively unradiogenic and internally inhomogeneous isotopic composition (²⁰⁶Pb/²⁰⁴Pb = 18.07–18.49), most likely generated by mixing of Pb from isotopically heterogeneous clastic sources. These sulphides were remobilised and enriched after the Lufilian Orogeny, along reactivated and newly formed NE–SW-oriented faults into a chalcocite-dominated Cu–Ag mineralisation of high economic interest. The chalcocite samples contain only trace amounts of lead and show mostly radiogenic Pb isotope signatures that fall along a linear trend in the ²⁰⁷Pb/²⁰⁴Pb vs. ²⁰⁶Pb/²⁰⁴Pb diagram (²⁰⁶Pb/²⁰⁴Pb = 18.66–23.65; ²⁰⁷Pb/²⁰⁴Pb = 15.72–16.02). These anomalous characteristics reflect a two-stage evolution involving admixture of both radiogenic lead and uranium during a young fluid event possibly c. 100 Ma ago. The Pb isotope systematics of local host rocks to mineralisation also indicate some comparable young disturbance of their U–Th–Pb systems, related to the same event. They could have provided Pb with sufficiently radiogenic compositions that was added to less radiogenic Pb remobilised from precursor Cu–Pb–Zn–Fe polysulphides, whereas the U most likely originated from external sources. Local metal sources are also suggested by the ²⁰⁸Pb/²⁰⁴Pb–²⁰⁶Pb/²⁰⁴Pb systematics of combined ore and rock lead, which indicate a pronounced and diversified lithological control of the immediate host rocks on the chalcocite-dominated Cu–Ag ores. The Pb isotope systematics of polysulphide mineralisation on the Kundelungu Plateau clearly record a diachronous evolution.  相似文献   

GRS evidence and the possibility of paleooceans on Mars     

James M. Dohm  Victor R. Baker  William V. Boynton  Alberto G. Fairén  Justin C. Ferris  Michael Finch  Roberto Furfaro  Trent M. Hare  Daniel M. Janes  Jeffrey S. Kargel  Suniti Karunatillake  John Keller  Kris Kerry  Kyeong J. Kim  Goro Komatsu  William C. Mahaney  Dirk Schulze-Makuch  Lucia Marinangeli  Gian G. Ori  Javier Ruiz  Shawn J. Wheelock 《Planetary and Space Science》2009,57(5-6):664-684

The Gamma Ray Spectrometer (Mars Odyssey spacecraft) has revealed elemental distributions of potassium (K), thorium (Th), and iron (Fe) on Mars that require fractionation of K (and possibly Th and Fe) consistent with aqueous activity. This includes weathering, evolution of soils, and transport, sorting, and deposition, as well as with the location of first-order geomorphological demarcations identified as possible paleoocean boundaries. The element abundances occur in patterns consistent with weathering in situ and possible presence of relict or exhumed paleosols, deposition of weathered materials (salts and clastic minerals), and weathering/transport under neutral to acidic brines. The abundances are explained by hydrogeology consistent with the possibly overlapping alternatives of paleooceans and/or heterogeneous rock compositions from diverse provenances (e.g., differing igneous compositions).  相似文献   

Surface-rupturing history of the Bree fault scarp, Roer Valley graben: Evidence for six events since the late Pleistocene     

Kris Vanneste  Koen Verbeeck  Thierry Camelbeeck  Etienne Paulissen  Mustapha Meghraoui  François Renardy  Denis Jongmans  Manfred Frechen 《Journal of Seismology》2001,5(3):329-359

Since 1996 paleoseismological investigations have been used to develop the surface- rupturing history of the Bree fault scarp, the morphologically best-defined segment of the southwestern border fault of the Roer Valley graben in northeastern Belgium. The first studies determined that the escarpment is associated with a surface fault, and they exposed evidence for three surface displacements since about 40 ka BP. The most recent eventprobably occurred between 1000 and 1350 yr cal BP. Geophysical and trenching studies at a new site near the southeastern end of the fault scarp reconfirmed the coincidence of the frontal escarpment with a shallow normal fault, which displaces the Middle Pleistocene `Main Terrace' of the Maas River, as well as overlying coversands of Saalian to late Weichselian age. Different amounts of displacement shown by the two youngest coversand units indicate two discrete faulting events, but primary evidence for the coseismic nature of these events is sparse. Radiocarbon and optically stimulated luminescence dating constrainthe age of these events to the Holocene and between 14.0 ± 2.3 ka BP and 15.8 ± 2.9 ka BP, respectively. In addition, four older surface-rupturing events are inferred from the presence of four wedge-shaped units of reworked Main Terrace deposits that are interbedded with coversand units in the hanging wall of the trench and in shallow boreholes. These wedges are interpreted as colluvial wedges, produced by accelerated slope processes in response torejuvenation of the fault scarp, most probably in a periglacial environment. Luminescence dating indicates that five out of a total of six identified faulting events are younger than 136.6 ± 17.6 ka. The antepenultimate event was the largest faulting event, associated with a total fault displacement in excess of 1 m. Thus, the newly investigated trench site represents the longest and most complete record of surface rupturing recovered so far along the Bree fault scarp. This study also demonstrates the viability of the paleoseismological approach to identify past large earthquakes in areas of present-day moderate to low seismic activity.  相似文献   

Growth, feeding, production, and consumption in 0-group bib (Trisopterus luscus L.) and whiting (Merlangius merlangus L.) in a shallow coastal area of the south-west Netherlands     

Hamerlynck  Olivier; Hostens  Kris 《ICES Journal of Marine Science》1993,50(1):81-91

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