Science.gov

Sample records for geological time scale

  1. Geologic time scale bookmark

    USGS Publications Warehouse

    U.S. Geological Survey

    2012-01-01

    This bookmark, designed for use with U.S. Geological Survey activities at the 2nd USA Science and Engineering Festival (April 26–29, 2012), is adapted from the more detailed Fact Sheet 2010–3059 "Divisions of Geologic Time." The information that it presents is widely sought by educators and students.

  2. Teaching about time by understanding Geologic Time Scales: The Geological Society of America Geologic Time Scale and its history

    NASA Astrophysics Data System (ADS)

    Geissman, J. W.; Walker, J. D.

    2012-12-01

    Geologic time scales, of one form or another, are used in most undergraduate geosciences courses, even including introductory physical geology or equivalent. However, satisfactory discussions of how geologic time scales originated, and how they have evolved to modern versions, are far too often conveniently or inconveniently left out of classroom discussions. Yet it is these kinds of discussions that have the potential of solidifying student appreciation of deep time and rates of geologic processes. We use the history and development of the Geological Society of America Geologic Time Scale, which reflects major developments in the fields of stratigraphy, geochronology, magnetic polarity stratigraphy, astrochronology, and chemostratigraphy, as a focus of how specific details of time scales can be used to teach about time. Advances in all of these fields have allowed many parts of the time scale to be calibrated to precisions approaching less than 0.05 %. Notable time intervals for which collaborative, multifaceted efforts have led to dramatic improvements in our understanding of the character and temporal resolution of key evolutionary events, in both marine and terrestrial environments, include the Triassic-Jurassic, Permo-Triassic, and Neoproterozoic-Phanerozoic boundaries (or transitions). Many of the details, but certainly not all, can be incorporated in discussions of how we know about geologic time in the classroom. For example, we presently understand that both the end-Permian ecological crisis and the biostratigraphic Permian-Triassic boundary, as calibrated by conodonts, lie within a ca. 700 ka long normal polarity chron. The reverse to normal polarity transition at the beginning of this chron is ca. 100 ka earlier than the ecological crisis and thus slightly older than the current estimate, based on high precision U-Pb zircon age determinations, of ca. 252.4 Ma for the Permian-Triassic boundary. This polarity transition occurred during the early part of

  3. Reconciling Changes to the Geologic Time Scale, in the U.S. Geologic Names Lexicon

    NASA Astrophysics Data System (ADS)

    Soller, D. R.; Stamm, N. R.

    2014-12-01

    The U.S. Geologic Names Lexicon ("Geolex", http://ngmdb.usgs.gov/Geolex/), is a standard reference for the Nation's stratigraphic nomenclature. Geolex's content is drawn from the literature published since the late 1800's. Since that time, modifications to the geologic time scale have been significant, particularly in recent decades (e.g., the Ordovician, Carboniferous, Permian, and Quaternary), owing in part to more precise biostratigraphic zonations and advances in isotopic dating techniques. Because the definitions of geologic time intervals have been modified as more information is gathered, interpreted, and published, the geologic age of a unit as stated in a report published in, for example, 1950, may be different according to today's time scale. In order to ensure that people can search Geolex for geologic units according to today's time scale, we have updated to the modern time scale the age estimates for many geologic units. These updated age estimates are shown in Geolex's "Unit Summary" pages; the ages as originally determined are preserved in the synopsis for each publication. This presentation will focus on our methodology.

  4. Improving the Geologic Time Scale (Jean Baptiste Lamarck Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Gradstein, Felix M.

    2010-05-01

    The Geologic Time Scale (GTS) provides the framework for the physical, chemical and biological processes on Earth. The time scale is the tool "par excellence" of the geological trade, and insight in its construction, strength, and limitations enhances its function and its utility. Earth scientists should understand how time scales are constructed and its myriad of physical and abstract data are calibrated, rather than merely using ages plucked from a convenient chart or card. Calibration to linear time of the succession of events recorded in the rocks on Earth has three components: (1) the standard stratigraphic divisions and their correlation in the global rock record, (2) the means of measuring linear time or elapsed durations from the rock record, and (3) the methods of effectively joining the two scales, the stratigraphic one and the linear one. Under the auspices of the International Commission on Stratigraphy (ICS), the international stratigraphic divisions and their correlative events are now largely standardized, especially using the GSSP (Global Stratigraphic Section and Point) concept. The means of measuring linear time or elapsed durations from the rock record are objectives in the EARTH TIME and GTS NEXT projects, that also are educating a new generation of GTS dedicated scientists. The U/Pb, Ar/Ar and orbital tuning methods are intercalibrated, and external error analysis improved. Existing Ar/Ar ages become almost 0.5% older, and U/Pb ages stratigraphically more realistic. The new Os/Re method has potential for directly dating more GSSP's and its correlative events. Such may reduce scaling uncertainty between the sedimentary levels of an age date and that of a stage boundary. Since 1981, six successive Phanerozoic GTS have been published, each new one achieving higher resolution and more users. The next GTS is scheduled for 2011/2012, with over 50 specialists taking part. New chapters include an expanded planetary time scale, sequence stratigraphy

  5. A SKOS-based multilingual thesaurus of geological time scale for interoperability of online geological maps

    NASA Astrophysics Data System (ADS)

    Ma, Xiaogang; Carranza, Emmanuel John M.; Wu, Chonglong; van der Meer, Freek D.; Liu, Gang

    2011-10-01

    The usefulness of online geological maps is hindered by linguistic barriers. Multilingual geoscience thesauri alleviate linguistic barriers of geological maps. However, the benefits of multilingual geoscience thesauri for online geological maps are less studied. In this regard, we developed a multilingual thesaurus of geological time scale (GTS) to alleviate linguistic barriers of GTS records among online geological maps. We extended the Simple Knowledge Organization System (SKOS) model to represent the ordinal hierarchical structure of GTS terms. We collected GTS terms in seven languages and encoded them into a thesaurus by using the extended SKOS model. We implemented methods of characteristic-oriented term retrieval in JavaScript programs for accessing Web Map Services (WMS), recognizing GTS terms, and making translations. With the developed thesaurus and programs, we set up a pilot system to test recognitions and translations of GTS terms in online geological maps. Results of this pilot system proved the accuracy of the developed thesaurus and the functionality of the developed programs. Therefore, with proper deployments, SKOS-based multilingual geoscience thesauri can be functional for alleviating linguistic barriers among online geological maps and, thus, improving their interoperability.

  6. Ontology-aided annotation, visualization, and generalization of geological time-scale information from online geological map services

    NASA Astrophysics Data System (ADS)

    Ma, Xiaogang; Carranza, Emmanuel John M.; Wu, Chonglong; van der Meer, Freek D.

    2012-03-01

    Geological maps are increasingly published and shared online, whereas tools and services supporting information retrieval and knowledge discovery are underdeveloped. In this study, we developed an ontology of geological time scale by using a Resource Description Framework model to represent the ordinal hierarchical structure of the geological time scale and to encode collected annotations of geological time scale concepts. We also developed an animated graphical view of the developed ontology, and functions for interactions between the ontology, the animation and online geological maps published as layers of OGC Web Map Service. The featured functions include automatic annotations for geological time concepts recognized from a geological map, changing layouts in the animation to highlight a concept, showing legends of geological time contents in an online map with the animation, and filtering out and generalizing geological time features in an online map by operating the map legend shown in the animation. We set up a pilot system and carried out a user survey to test and evaluate the usability and usefulness of the developed ontology, animation and interactive functions. Results of the pilot system and the user survey demonstrate that our works enhance features of online geological map services and they are helpful for users to understand and to explore geological time contents and features, respectively, of a geological map.

  7. Native American Students' Understanding of Geologic Time Scale: 4th-8th Grade Ojibwe Students' Understanding of Earth's Geologic History

    ERIC Educational Resources Information Center

    Nam, Younkyeong; Karahan, Engin; Roehrig, Gillian

    2016-01-01

    Geologic time scale is a very important concept for understanding long-term earth system events such as climate change. This study examines forty-three 4th-8th grade Native American--particularly Ojibwe tribe--students' understanding of relative ordering and absolute time of Earth's significant geological and biological events. This study also…

  8. Geologic Time.

    ERIC Educational Resources Information Center

    Albritton, Claude C., Jr.

    1984-01-01

    Discusses the historical development of the concept of geologic time. Develops the topic by using the major discoveries of geologists, beginning with Steno and following through to the discovery and use of radiometric dating. An extensive reference list is provided. (JM)

  9. Use of a Walk Through Time to Facilitate Student Understandings of the Geological Time Scale

    NASA Astrophysics Data System (ADS)

    Shipman, H. L.

    2004-12-01

    Students often have difficulties in appreciating just how old the earth and the universe are. While they can simply memorize a number, they really do not understand just how big that number really is, in comparison with other, more familiar student referents like the length of a human lifetime or how long it takes to eat a pizza. (See, e.g., R.D. Trend 2001, J. Research in Science Teaching 38(2): 191-221) Students, and members of the general public, also display such well-known misconceptions as the "Flintstone chronology" of believing that human beings and dinosaurs walked the earth at the same time. (In the classic American cartoon "The Flintstones," human beings used dinosaurs as draft animals. As scientists we know this is fiction, but not all members of the public understand that.) In an interdisciplinary undergraduate college class that dealt with astronomy, cosmology, and biological evolution, I used a familiar activity to try to improve student understanding of the concept of time's vastness. Students walked through a pre-determined 600-step path which provided a spatial analogy to the geological time scale. They stopped at various points and engaged in some pre-determined discussions and debates. This activity is as old as the hills, but reports of its effectiveness or lack thereof are quite scarce. This paper demonstrates that this activity was effective for a general-audience, college student population in the U.S. The growth of student understandings of the geological time scale was significant as a result of this activity. Students did develop an understanding of time's vastness and were able to articulate this understanding in various ways. This growth was monitored through keeping track of several exam questions and through pre- and post- analysis of student writings. In the pre-writings, students often stated that they had "no idea" about how to illustrate the size of the geological time scale to someone else. While some post-time walk responses

  10. Structure and dating errors in the geologic time scale and periodicity in mass extinctions

    NASA Technical Reports Server (NTRS)

    Stothers, Richard B.

    1989-01-01

    Structure in the geologic time scale reflects a partly paleontological origin. As a result, ages of Cenozoic and Mesozoic stage boundaries exhibit a weak 28-Myr periodicity that is similar to the strong 26-Myr periodicity detected in mass extinctions of marine life by Raup and Sepkoski. Radiometric dating errors in the geologic time scale, to which the mass extinctions are stratigraphically tied, do not necessarily lessen the likelihood of a significant periodicity in mass extinctions, but do spread the acceptable values of the period over the range 25-27 Myr for the Harland et al. time scale or 25-30 Myr for the DNAG time scale. If the Odin time scale is adopted, acceptable periods fall between 24 and 33 Myr, but are not robust against dating errors. Some indirect evidence from independently-dated flood-basalt volcanic horizons tends to favor the Odin time scale.

  11. Consistent allometric scaling of stomatal sizes and densities across taxonomic ranks and geologic time

    NASA Astrophysics Data System (ADS)

    de Boer, H. J.; Price, C. A.; Wagner-Cremer, F.; Dekker, S. C.; Veneklaas, E. J.

    2013-12-01

    Stomatal pores on plants leaves are an important link in the chain of processes that determine biosphere fluxes of water and carbon. Stomatal density (i.e. the number of stomata per area) and the size of the stomatal pore at maximum aperture are particularly relevant traits in this context because they determine the theoretical maximum diffusive stomatal conductance (gsmax) and thereby set an upper limit for leaf gas exchange. Observations on (sub)fossil leaves revealed that changes in stomatal densities are anti-correlated with changes in stomatal sizes at developmental and evolutionary timescales. Moreover, this anti-correlation appears consistently within single species, across multiple species in the extant plant community and at evolutionary time scales. The consistency of the relation between stomatal densities and sizes suggests that common mechanisms constrain the adaptation of these traits across the plant community. In an attempt to identify such potential generic constraints, we investigated the allometry between stomatal densities and sizes in the extant plant community and across geological time. As the size of the stomatal pore at maximum aperture is typically derived from the length of the stomatal pore, we considered the allometric scaling of pore length (lp) with stomatal density (Ds) as the power law: lp = k . Dsa in which k is a normalization constant and the exponent a is the slope of the scaling relation. Our null-hypothesis predicts that stomatal density and pore length scale along a constant slope of -1/2 based on a scale-invariant relation between pore length and the distance between neighboring pores. Our alternative hypothesis predicts a constant slope of -1 based on the idea that stomatal density and pore length scale along an invariant gsmax. To explore these scaling hypotheses in the extant plant community we compiled a dataset of combined observations of stomatal density and pore length on 111 species from published literature and new

  12. "Tectonic Petrameter," An Alternative Method to Teaching the Geologic Time Scale

    NASA Astrophysics Data System (ADS)

    Posner, E. S.

    2011-12-01

    I have over a decade of experience as a performance poet and am now a graduate student in the geosciences. I have created a performance poem / play script, "Tectonic Petrameter," as an alternative method of teaching the geologic time scale. "The Archean came next and it was a blast. Tectonic plates were smaller and they moved pretty fast. In an enthusiastic flash of ash, volcanic islands smashed together." The use of rhyme and rhythm presents a different and interdisciplinary approach to teaching Earth history that appeals to a wide range of learning styles and makes science fun, while clearly describing important concepts in geology and events in Earth history. "Now it's time to get down with the Coal Swamp Stomp! Tap your feet to the beat of the formation of peat like a plant plantation soaking up the bright heat." "Tectonic Petrameter" by itself is an illustrated spoken-word poem that leads audiences from all levels of scientific background on an excitingly educational journey through geologic time. I will perform my 10-minute memorized poem and present results from my ongoing study to assess the effectiveness of "Tectonic Petrameter" as a teaching tool in K-12 and introductory undergraduate classroom curricula. I propose that using "Tectonic Petrameter" as a performance piece and theatrical play script in K-12 and introductory undergraduate classrooms, as well as in broader community venues, may be an avenue for breaking down barriers related to teaching about Earth's long and complex history. Digital copies of "Tectonic Petrameter" will be made available to interested parties.

  13. The geocenter motion from decadal to geological time-scales: geophysical modelling

    NASA Astrophysics Data System (ADS)

    Greff-Lefftz, M.; Métivier, L.

    2012-04-01

    Among the coefficients of the spherical harmonics expansion of elasto-gravitational deformations, the degree-one has particular characteristics related to geodesy as well as to mechanics. It is linked to the position of the Earth centre of mass and is strongly dependent on the choice of the origin of the reference frame. We investigate here the geocenter motion, that is to say the geometric centre of the translated external surface with respect to the centre of mass, for different internal excitation sources at different time-scales. At decadal time-scale, we find that the geocenter motion induced by geostrophic pressures within the fluid core acting at both the core-mantle and inner core boundaries is at a level of 0.1 mm/yr. At secular time-scale, geocenter motions induced by post-glacial rebound have been shown to be at the level of -0.4 - 0.2 mm/yr Finally, at geological time-scale, we quantify degree-one deformations induced by internal loads within the mantle. We use a simple model in which we assume that subducted plates sink vertically through the mantle, and in which upwelling domes are stable over the last 120 Ma. We found that, although the associated geocenter secular motion is one order of magnitude smaller than the one induced by post-glacial rebound, there is a significant discrepancy of about a few hundred meters between the centre of figure and the centre of mass of the Earth. Is it possible to detect, at the present time, with geodetic measurements, such a permanent translation?

  14. Neogene and Quaternary coexisting in the geological time scale: The inclusive compromise

    NASA Astrophysics Data System (ADS)

    McGowran, Brian; Berggren, Bill; Hilgen, Frits; Steininger, Fritz; Aubry, Marie-Pierre; Lourens, Lucas; Van Couvering, John

    2009-11-01

    Removing the Tertiary and Quaternary Periods whilst conserving the Paleogene and Neogene Periods in The Geological Timescale 2004 caused a storm of protest. One response was to advocate restoring an enlarged Quaternary and consigning the Neogene to a minor role within the Tertiary. Amongst an array of practical, traditional, sentimental and anthropocentric reasons for this response, the one hard-core justification was that the rigidly nested hierarchy of the geological timescale must be preserved. The central objective of this paper is conserving the historically legitimate, Miocene-present, Neogene Period and System. There are two options for conserving the Quaternary concurrently with the Neogene: (i) an inclusive compromise in a flexible hierarchy, and (ii) an upgrading of Pliocene and Pleistocene divisions to the level of epoch. In the inclusive compromise there coexist alternative pathways through the hierarchical ranks. Thus geohistorians and biohistorians have two options for traversing the hierarchy from era to age, as in this example using the hierarchical positioning of the Calabrian Age and Stage: either Cenozoic [era]↔Neogene [period]↔Pleistocene [epoch]↔Calabrian [age], or Cenozoic [era]↔Quaternary [subera]↔Pleistocene [epoch]↔Calabrian [age]. We reaffirm that the inclusive compromise is entirely viable. In so doing we (i) challenge the necessity of the rigidly nested hierarchy, which should be capable of a little flexibility; (ii) reject all analogies of the arbitrary and conventional chronostratigraphic hierarchy with three natural biological hierarchies; (iii) reaffirm the integrity of the Neogene extending to the present; and (iv) see no reason to doubt the harmonious coexistence of the two options preserving the Quaternary and Neogene traditions in an orderly working and stable time scale. In the alternative schema conserving the Neogene, divisions of the Pliocene and Pleistocene are upgraded, so that the Late Pleistocene, Early

  15. Advances in the Geomagnetic Polarity Time Scale--Developments and Integration with the Geologic Time Scale and Future Directions (Invited)

    NASA Astrophysics Data System (ADS)

    Geissman, J. W.

    2013-12-01

    We celebrate the 50th anniversary of the publication of the Vine-Matthews/Morley-Larochelle hypothesis (Vine and Matthews, Nature, 1963, v. 199, #4897, p. 947-949), which integrated marine magnetic anomaly data with a rapidly evolving terrestrial-based geomagnetic polarity time scale (GPTS). The five decades of research since 1963 have witnessed the expansion and refinement of the GPTS, to the point where ages of magnetochron boundaries, in particular in the Cenozoic, can be estimated with uncertainties better than 0.1%. This has come about by integrating high precision geochronology, cyclostratigraphy at different time scales, and magnetic polarity data of increased quality, allowing extension of the GPTS back into the Paleozoic. The definition of a high resolution GPTS across time intervals of major events in Earth history has been of particular interest, as a specific magnetochron boundary correlated across several localities represents a singular global datum. A prime example is the end Permian, when some 80 percent of genus-level extinctions and a range of 75 to 96 percent species- level extinctions took place in the marine environment, depending upon clade. Much our understanding of the Permian-Triassic boundary (PTB) is based on relatively slowly deposited marine sequences in Europe and Asia, yet a growing body of observations from continental sequences demonstrates a similar extinction event and new polarity data from some of these sequences are critical to refining the GPTS across the PTB and testing synchronicity of marine and terrestrial events. The data show that the end-Permian ecological crisis and the conodont calibrated biostratigraphic PTB both followed a key polarity reversal between a short interval (subchron) of reverse polarity to a considerably longer (chron) of normal polarity. Central European Basin strata (continental Permian and epicontinental Triassic) yield high-quality magnetic polarity stratigraphic records (Szurlies et al., 2003

  16. Calibration of the geologic time scale: Cenozoic and Late Cretaceous glauconite and nonglauconite dates compared

    SciTech Connect

    Craig, L.E.; Smith, A.G. ); Armstrong, R.L. )

    1989-09-01

    Revision of the 1982 time scale of Harland et al. has led to the compilation of 377 isotopic dates for calibration of the Cenozoic to Cretaceous time interval. The results show that the ages of stage boundaries based on glauconite dates are on average about 2 m.y. younger than those based on nonglauconite dates, but for many Cenozoic and Late Cretaceous stages the differences are too small to require special consideration of glauconite dates. Future work may reveal an irreducible systematic difference between glauconite and nonglauconite time scales, but the progress made so far in recognizing those glauconites likely to yield reliable dates for the Cenozoic to Late Cretaceous interval may continue to provide useful time-scale calibration points.

  17. Joint EM-NE-International Study of Glass Behavior over Geologic Time Scales

    SciTech Connect

    Ryan, Joseph V.; Ebert, W. L.; Icenhower, Jonathan P.; Schreiber, Daniel K.; Strachan, Denis M.; Vienna, John D.

    2012-03-30

    Vitrification has been chosen as the best demonstrated available technology for waste immobilization worldwide. To date, the contributions of physical and chemical processes controlling the long-term glass dissolution rate in geologic disposal remain uncertain; leading to a lack of international consensus on a glass corrosion rate law. Existing rate laws have overcome the uncertainty through conservatism, but a thorough mechanistic understanding of waste form durability in geologic environments would improve public and regulator confidence, as well as lead to cost savings if it is possible to take credit for the true durability of the waste form itself in system evaluations. To this end, six nations have joined together to formulate a joint plan for collaborative research into the mechanisms controlling the long-term corrosion of glass. This report highlights the technical program plan behind the US portion of this effort, with an emphasis on the current understanding (and limitations) of several mechanistic theories for glass corrosion. Some recent results are presented to provide an example of the ongoing research.

  18. Controls on the Stability of Atmospheric O2 over Geologic Time Scales (Invited)

    NASA Astrophysics Data System (ADS)

    Rothman, D.; Bosak, T.

    2013-12-01

    The concentration of free oxygen in Earth's surface environment represents a balance between the accumulation of O2, due to long-term burial of organic carbon in sediments, and the consumption of O2 by weathering processes and the oxidation of reduced gases. The stability of modern O2 levels is typically attributed to a negative feedback that emerges when the production and consumption fluxes are expressed as a function of O2 concentration. Empirical studies of modern burial of organic carbon suggest that the production of O2 is a logarithmically decreasing function of the duration of time---the "oxygen exposure time (OET)"--over which sedimentary organic carbon is exposed to O2. The OET hypothesis implies that a fraction of organic matter is physically protected from anaerobic decay by its association with clay-sized mineral surface area, but susceptible to aerobic decay, either oxidatively or via free extracellular hydrolytic enzymes. By assuming that the long-term aerobic degradation is diffusion-limited, we predict the logarithmic decay of the OET curve. We note, however, that exposure to O2 may enhance not only degradation but also physical protection due to the precipitation of iron oxides and clay minerals. When the rate of transformation from the unprotected state to the protected state exceeds a small fraction of the average oxidative degradation rate, our theoretical OET curve develops a maximum at small O2 exposure times. In this case, the equilibrium O2 concentration can lose its stability. These observations may help explain major fluctuations in Earth's carbon cycle and the rise of O2 during the Proterozoic (2000--542 Ma).

  19. Stabilization of large drainage basins over geological time scales: Cenozoic West Africa, hot spot swell growth, and the Niger River

    NASA Astrophysics Data System (ADS)

    Chardon, Dominique; Grimaud, Jean-Louis; Rouby, Delphine; Beauvais, Anicet; Christophoul, Frédéric

    2016-03-01

    Reconstructing the evolving geometry of large river catchments over geological time scales is crucial to constraining yields to sedimentary basins. In the case of Africa, it should further help deciphering the response of large cratonic sediment routing systems to Cenozoic growth of the basin-and-swell topography of the continent. Mapping of dated and regionally correlated lateritic paleolandscape remnants complemented by onshore sedimentological archives allows the reconstruction of two physiographic configurations of West Africa in the Paleogene. Those reconstructions show that the geometry of the drainage is stabilized by the late early Oligocene (29 Ma) and probably by the end of the Eocene (34 Ma), allowing to effectively link the inland morphoclimatic record to offshore sedimentation since that time, particularly in the case of the Niger catchment—delta system. Mid-Eocene paleogeography reveals the antiquity of the Senegambia catchment back to at least 45 Ma and suggests that a marginal upwarp forming a continental divide preexisted early Oligocene connection of the Niger and Volta catchments to the Equatorial Atlantic Ocean. Such a drainage rearrangement was primarily enhanced by the topographic growth of the Hoggar hot spot swell and caused a stratigraphic turnover along the Equatorial margin of West Africa.

  20. Regional fluid flow and heat distribution over geological time scales at the margin of unconfined and confined carbonate sequences

    NASA Astrophysics Data System (ADS)

    Havril, Timea; Mádl-Szönyi, Judit; Molson, John

    2016-04-01

    permeability confining formation, which facilitates buoyancy-driven flow by restricting the dissipation of heat. Over geological time, these cells were gradually overprinted by gravity-driven flow and thermal advection due to the uplift of the western part of the system. The limited thickness of the cover along the western block allowed efficient water infiltration into the system, which leads to an increased cooling effect. Further uplifting of the western part leads to a change of the main character of the flow patterns, with gravity-driven groundwater flow dominating over the effect of buoyancy-driven flow. Although cooling of the system has significantly progressed, conditions over the confined part of the system are still favorable for the development of thermal convection cells, and leads to significant heat accumulation under the confined sub-basin. The flow and heat transport simulations have helped to derive the main evolutionary characteristics of groundwater flow and heat transport patterns for the unconfined and confined parts of the region. The result is flow convergence toward the discharge zone from different sources over geological time scales. This is decisive for heat accumulation as well as for the development of a deep geothermal energy potential in confined carbonates. The research is supported by the Hungarian Research Fund.

  1. A framework for predicting global silicate weathering and CO2 drawdown rates over geologic time-scales.

    PubMed

    Hilley, George E; Porder, Stephen

    2008-11-01

    Global silicate weathering drives long-time-scale fluctuations in atmospheric CO(2). While tectonics, climate, and rock-type influence silicate weathering, it is unclear how these factors combine to drive global rates. Here, we explore whether local erosion rates, GCM-derived dust fluxes, temperature, and water balance can capture global variation in silicate weathering. Our spatially explicit approach predicts 1.9-4.6 x 10(13) mols of Si weathered globally per year, within a factor of 4-10 of estimates of global silicate fluxes derived from riverine measurements. Similarly, our watershed-based estimates are within a factor of 4-18 (mean of 5.3) of the silica fluxes measured in the world's ten largest rivers. Eighty percent of total global silicate weathering product traveling as dissolved load occurs within a narrow range (0.01-0.5 mm/year) of erosion rates. Assuming each mol of Mg or Ca reacts with 1 mol of CO(2), 1.5-3.3 x 10(8) tons/year of CO(2) is consumed by silicate weathering, consistent with previously published estimates. Approximately 50% of this drawdown occurs in the world's active mountain belts, emphasizing the importance of tectonic regulation of global climate over geologic timescales. PMID:18952842

  2. A framework for predicting global silicate weathering and CO2 drawdown rates over geologic time-scales

    PubMed Central

    Hilley, George E.; Porder, Stephen

    2008-01-01

    Global silicate weathering drives long-time-scale fluctuations in atmospheric CO2. While tectonics, climate, and rock-type influence silicate weathering, it is unclear how these factors combine to drive global rates. Here, we explore whether local erosion rates, GCM-derived dust fluxes, temperature, and water balance can capture global variation in silicate weathering. Our spatially explicit approach predicts 1.9–4.6 × 1013 mols of Si weathered globally per year, within a factor of 4–10 of estimates of global silicate fluxes derived from riverine measurements. Similarly, our watershed-based estimates are within a factor of 4–18 (mean of 5.3) of the silica fluxes measured in the world's ten largest rivers. Eighty percent of total global silicate weathering product traveling as dissolved load occurs within a narrow range (0.01–0.5 mm/year) of erosion rates. Assuming each mol of Mg or Ca reacts with 1 mol of CO2, 1.5–3.3 × 108 tons/year of CO2 is consumed by silicate weathering, consistent with previously published estimates. Approximately 50% of this drawdown occurs in the world's active mountain belts, emphasizing the importance of tectonic regulation of global climate over geologic timescales. PMID:18952842

  3. Global Warming in Geologic Time

    ScienceCinema

    David Archer

    2010-01-08

    The notion is pervasive in the climate science community and in the public at large that the climate impacts of fossil fuel CO2 release will only persist for a few centuries. This conclusion has no basis in theory or models of the atmosphere / ocean carbon cycle, which we review here. The largest fraction of the CO2 recovery will take place on time scales of centuries, as CO2 invades the ocean, but a significant fraction of the fossil fuel CO2, ranging in published models in the literature from 20-60%, remains airborne for a thousand years or longer. Ultimate recovery takes place on time scales of hundreds of thousands of years, a geologic longevity typically associated in public perceptions with nuclear waste. The glacial / interglacial climate cycles demonstrate that ice sheets and sea level respond dramatically to millennial-timescale changes in climate forcing. There are also potential positive feedbacks in the carbon cycle, including methane hydrates in the ocean, and peat frozen in permafrost, that are most sensitive to the long tail of the fossil fuel CO2 in the atmosphere.

  4. Global Warming in Geologic Time

    SciTech Connect

    David Archer

    2008-02-27

    The notion is pervasive in the climate science community and in the public at large that the climate impacts of fossil fuel CO2 release will only persist for a few centuries. This conclusion has no basis in theory or models of the atmosphere / ocean carbon cycle, which we review here. The largest fraction of the CO2 recovery will take place on time scales of centuries, as CO2 invades the ocean, but a significant fraction of the fossil fuel CO2, ranging in published models in the literature from 20-60%, remains airborne for a thousand years or longer. Ultimate recovery takes place on time scales of hundreds of thousands of years, a geologic longevity typically associated in public perceptions with nuclear waste. The glacial / interglacial climate cycles demonstrate that ice sheets and sea level respond dramatically to millennial-timescale changes in climate forcing. There are also potential positive feedbacks in the carbon cycle, including methane hydrates in the ocean, and peat frozen in permafrost, that are most sensitive to the long tail of the fossil fuel CO2 in the atmosphere.

  5. Global Warming in Geologic Time

    SciTech Connect

    Archer, David

    2008-02-27

    The notion is pervasive in the climate science community and in the public at large that the climate impacts of fossil fuel CO2 release will only persist for a few centuries. This conclusion has no basis in theory or models of the atmosphere/ ocean carbon cycle, which we review here. The largest fraction of the CO2 recovery will take place on time scales of centuries, as CO2 invades the ocean, but a significant fraction of the fossil fuel CO2, ranging in published models in the literature from 20-60%, remains airborne for a thousand years or longer. Ultimate recovery takes place on time scales of hundreds of thousands of years, a geologic longevity typically associated in public perceptions with nuclear waste. The glacial/interglacial climate cycles demonstrate that ice sheets and sea level respond dramatically to millennial-timescale changes in climate forcing. There are also potential positive feedbacks in the carbon cycle, including methane hydrates in the ocean, and peat frozen in permafrost, that are most sensitive to the long tail of the fossil fuel CO2 in the atmosphere.

  6. Variations in barrier-island evolution at millennial and decadal time scales related to underlying geology, Onslow Beach, NC USA

    NASA Astrophysics Data System (ADS)

    Yu, W.; Hood, D.; Browne, R.; Rodriguez, A. B.

    2010-12-01

    Located midway between Cape Fear and Cape Lookout, North Carolina, Onslow Beach is a 12 km-long barrier island, which historically had transgressive and stable profiles on the southern and northern ends, respectively. The northern half of the island has well-developed dunes in front of maritime forest. The southern half is low-lying and is characterized by washover fans infringing on salt marsh. By studying the underlying barrier lithology and structure, we will determine the evolution of the island at millennial time scales and in turn address whether the along-beach variations in barrier morphology and the historical shoreline-movement trends are related to the underlying geology. We collected 33 vibracores along 7 cross-shore transects spaced equally along Onslow Beach. Variations in topography were measured along these transects using an RTK-GPS. Cores collected from southern transects revealed multiple marsh-overwash sequences overlying estuarine deposits or a highly compacted unit typically composed of gray clay or brown medium to fine grained sand, possibly of Pleistocene age. The contact between this Pleistocene unit and the overlying estuarine deposits or thin peat layer represents the initial inundation of the area in response to Holocene sea-level rise. The elevation of this contact decreases towards the north along the island to a point where our coring methods could not penetrate deep enough to sample it (>4.0 m below the surface). In addition, marsh deposits sampled in the north below the island, which range from 30-120cm, were commonly found to be thicker than the marsh deposits sampled in the south, which range from 10-30 cm. These thick back-barrier units in the north preserve paleo overwash events as fining-upward sequences and likely accreted and were preserved due to the large accommodation space that the deep Pleistocene surface provided. The stratigraphy of the northern cores indicates a less stable Island in the past dominated by overwash

  7. On a coupled evolution of Earth's mantle and core: Implications for magnetic evolution over the geologic time-scale

    NASA Astrophysics Data System (ADS)

    Nakagawa, Takashi

    2015-04-01

    According to the recent progress of numerical modeling of mantle convection with various realistic physical processes, we can look into possible scenarios on core-mantle evolution suggested from theoretical and experimental studies with developing a coupled core-mantle evolution model in fully dynamical mantle convection simulations. The core evolution theory that allows to generate the inner core can be treated with the thermal boundary condition at the core-mantle boundary of mantle convection simulations. Here we introduce our recent accomplishments in a coupled core-mantle evolution: 1. Influence of early Earth differentiation and 2. Importance of hydrous minerals in the deep mantle. In the presentation, we will give implications for history of heat flow across the core-mantle boundary from early to present Earth and magnetic evolution over geologic time suggested from paleomagnetism measurements.

  8. Divisions of Geologic Time - Major Chronostratigraphic and Geochronologic Units

    USGS Publications Warehouse

    U.S. Geological Survey Geologic Names Committee

    2007-01-01

    Introduction Effective communication in the geosciences requires consistent uses of stratigraphic nomenclature, especially divisions of geologic time. A geologic time scale is composed of standard stratigraphic divisions based on rock sequences and calibrated in years (Harland and others, 1982). Over the years, the development of new dating methods and refinement of previous ones have stimulated revisions to geologic time scales. Since the mid-1990s, geologists from the U.S. Geological Survey (USGS), State geological surveys, academia, and other organizations have sought a consistent time scale to be used in communicating ages of geologic units in the United States. Many international debates have occurred over names and boundaries of units, and various time scales have been used by the geoscience community.

  9. Divisions of geologic time-major chronostratigraphic and geochronologic units

    USGS Publications Warehouse

    U.S. Geological Survey Geologic Names Committee

    2010-01-01

    Effective communication in the geosciences requires consistent uses of stratigraphic nomenclature, especially divisions of geologic time. A geologic time scale is composed of standard stratigraphic divisions based on rock sequences and is calibrated in years. Over the years, the development of new dating methods and the refinement of previous methods have stimulated revisions to geologic time scales. Advances in stratigraphy and geochronology require that any time scale be periodically updated. Therefore, Divisions of Geologic Time, which shows the major chronostratigraphic (position) and geochronologic (time) units, is intended to be a dynamic resource that will be modified to include accepted changes of unit names and boundary age estimates. This fact sheet is a modification of USGS Fact Sheet 2007-3015 by the U.S. Geological Survey Geologic Names Committee.

  10. A model for global diversity in response to temperature change over geological time scales, with reference to planktic organisms.

    PubMed

    De Blasio, Fabio Vittorio; Liow, Lee Hsiang; Schweder, Tore; De Blasio, Birgitte Freiesleben

    2015-01-21

    There are strong propositions in the literature that abiotic factors override biotic drivers of diversity on time scales of the fossil record. In order to study the interaction of biotic and abiotic forces on long term changes, we devise a spatio-temporal discrete-time Markov process model of macroevolution featuring population formation, speciation, migration and extinction, where populations are free to migrate. In our model, the extinction probability of these populations is controlled by latitudinally and temporally varying environment (temperature) and competition. Although our model is general enough to be applicable to disparate taxa, we explicitly address planktic organisms, which are assumed to disperse freely without barriers over the Earth's oceans. While rapid and drastic environmental changes tend to eliminate many species, generalists preferentially survive and hence leave generalist descendants. In other words, environmental fluctuations result in generalist descendants which are resilient to future environmental changes. Periods of stable or slow environmental changes lead to more specialist species and higher population numbers. Simulating Cenozoic diversity dynamics with both competition and the environmental component of our model produces diversity curves that reflect current empirical knowledge, which cannot be obtained with just one component. Our model predicts that the average temperature optimum at which planktic species thrive best has declined over the Neogene, following the trend of global average temperatures. PMID:25451532

  11. Constraining the Geological Time Scale for the Upper Cretaceous in the Edmonton Group: Western Canadian Sedimentary Basin

    NASA Astrophysics Data System (ADS)

    Heredia, B.; Gaylor, J. R.; Hilgen, F.; Kuiper, K.; Mezger, K.; Wijbrans, J. R.; Quidelleur, X.; Huesing, S.

    2011-12-01

    The Cretaceous period records evidence of sea-level changes, remarkably cyclic sedimentation, major perturbations in carbon cycles during anoxic events, and large scale igneous activity. Astronomically-tuned time scales are only partially consistent with recalculated Ar-Ar constraints for the Cretaceous-Paleogene (K-Pg) boundary, but differ in number and tuning of 405-kyr eccentricity related cycles. The exposures of Upper Cretaceous strata along the Red Deer River (Western Canadian Sedimentary Basin) offer a unique opportunity to examine aspects of marine, tectonic, and climatic influenced sediments. The uppermost part of the Knudsen Farm section is a well-preserved continuous section, mainly composed by climatically controlled alternations of silt and organic rich horizons, in which altered volcanic ash layers have been deposited. In this section, the K-Pg boundary has been placed at the base of a prominent coal layer (Nevis coal), approx. 24 m from the base of the c29r. We present a compilation of paleomagnetic data, chemical, colour and magnetic susceptibility proxies, and Ar-Ar, K-Ar and U-Pb (CA-TIMS) for the uppermost part of the Maastrichtian, including the base of the c29r to the K-Pg boundary and up to the lowermost Danian. High-resolution radioisotopic ages and the multi-proxy lithological and geochemical datasets are used to develop a cyclostratigraphic reconstruction of this interval, thus permitting the synchronisation of rock clocks close to the K-Pg boundary. This research is funded by the European Community's Seventh Framework Program (FP7/2007-2013) under grant agreement no [215458].

  12. Evolution of the South-East Monsoon System - An Investigation of the Dynamical Controls on the Monsoon System Over Geologic Time Scales.

    NASA Astrophysics Data System (ADS)

    Farnsworth, A.; Lunt, D. J.

    2014-12-01

    The South-East Asian monsoon is a fundamental feature in the global climate system cycling energy, moisture and momentum from tropical to extra-tropical latitudes. Societies rely extensively on precipitation during the monsoon season to sustain population centres and economic activity such as agriculture. However the current monsoon system has not always been in its current configuration varying extensively throughout geological time. However little is known about the driving factors behind its creation and evolution. A series of numerical model simulation (HadCM3L) using state of the art reconstructed paleogeographies have been employed to investigate the evolution of the S.E. Asian monsoon system for each geological stage (32 simulations in total) since the beginning of the Cretaceous. Two methodologies, i) a fixed regional precipitation signal based on the current monsoon regions modern areal extent and ii) a migrating regional construct based on the modern day monsoon regions back rotated through time are investigated. These two methodologies allow an examination of the evolution of tropical precipitation over time in the region. The large-scale processes (paleogeography, CO2) of the monsoon system and the regional dynamics (e.g. sea surface temperatures, regional atmospheric circulation, oceanic heat transport, land-sea temperature differential) that control them are also examined with numerical results compared against available proxy data. Preliminary results indicate a downward trend in global precipitation since the late Eocene with significant change at the E/O boundary. In addition, tropical precipitation (40°N - 40°S) has seen a downward trend in rainfall since the mid-Cretaceous. S.E. Asia is shown to be influenced by changes in topographical features/ location, CO2 concentrations, and the regional atmospheric circulation playing a key role in modification of the monsoon system which drive variability on tectonic time scales.

  13. Measuring Student Understanding of Geological Time

    ERIC Educational Resources Information Center

    Dodick, Jeff; Orion, Nir

    2003-01-01

    There have been few discoveries in geology more important than "deep time"--the understanding that the universe has existed for countless millennia, such that man's existence is confined to the last milliseconds of the metaphorical geological clock. The influence of deep time is felt in a variety of sciences including geology, cosmology, and…

  14. Geologic utility of small-scale airphotos

    NASA Technical Reports Server (NTRS)

    Clark, M. M.

    1969-01-01

    The geologic value of small scale airphotos is emphasized by describing the application of high altitude oblique and 1:120,000 to 1:145,000 scale vertical airphotos to several geologic problems in California. These examples show that small-scale airphotos can be of use to geologists in the following ways: (1) high altitude, high oblique airphotos show vast areas in one view; and (2) vertical airphotos offer the most efficient method of discovering the major topographic features and structural and lithologic characteristics of terrain.

  15. On the potential vegetation feedbacks that enhance phosphorus availability - insights from a process-based model linking geological and ecological time scales

    NASA Astrophysics Data System (ADS)

    Buendíia, C.; Arens, S.; Hickler, T.; Higgins, S. I.; Porada, P.; Kleidon, A.

    2013-12-01

    In old and heavily weathered soils, the availability of P might be so small that the primary production of plants is limited. However, plants have evolved several mechanisms to actively take up P from the soil or mine it to overcome this limitation. These mechanisms involve the active uptake of P mediated by mycorrhiza, biotic de-occlusion through root clusters, and the biotic enhancement of weathering through root exudation. The objective of this paper is to investigate how and where these processes contribute to alleviate P limitation on primary productivity. To do so, we propose a process-based model accounting for the major processes of the carbon, water, and P cycle including chemical weathering at the global scale. We use simulation experiments to assess the relative importance of the different uptake mechanisms to alleviate P limitation on biomass production. Implementing P limitation on biomass synthesis allows the assessment of the efficiencies of biomass production across different ecosystems. We find that active P-uptake is an essential mechanism for sustaining P availability on long time scales, whereas biotic de-occlusion might serve as a buffer on time scales shorter than 10 000 yr. Although active P uptake is essential for reducing P losses by leaching, humid lowland soils reach P limitation after around 100 000 yr of soil evolution. Given the generalized modeling framework, our model results compare reasonably with observed or independently estimated patterns and ranges of P concentrations in soils and vegetation. Furthermore, our simulations suggest that P limitation might be an important driver of biomass production efficiency (the fraction of the gross primary productivity used for biomass growth), and that vegetation on older soils becomes P-limited leading to a smaller biomass production efficiency. With this study, we provide a theoretical basis for investigating the responses of terrestrial ecosystems to P availability linking geological and

  16. Measuring student understanding of geological time

    NASA Astrophysics Data System (ADS)

    Dodick, Jeff; Orion, Nir

    2003-09-01

    There have been few discoveries in geology more important than deep time - the understanding that the universe has existed for countless millennia, such that man's existence is confined to the last milliseconds of the metaphorical geological clock. The influence of deep time is felt in a variety of sciences including geology, cosmology, and evolutionary biology. Thus, any student that wants to master these subjects must have a good understanding of geological time. Despite its critical importance, there has been very little attention given to geological time by science education researchers. Of the work that has been done, much of it ignores the cognitive basis for students' understanding of geological time. This work addresses this gap by presenting a validation study for a new instrument - the GeoTAT (Geological Time Aptitude Test). Consisting of a series of open puzzles, the GeoTAT tested the subjects' ability to reconstruct and represent the transformation in time of a series of geological structures. Montagnero (1992, 1996) terms this ability diachronic thinking. This instrument was distributed to a population of 285 junior and senior high school students with no background in geology, as well as 58 high school students majoring in geology. A comparison of the high school (grades 11-12) geology and non-geology majors indicated that the former group held a significant advantage over the latter in solving problems involving diachronic thinking. This relationship was especially strengthened by the second year of geological study (grade 12), with the key factor in this improvement being exposure to fieldwork. Fieldwork both improved the subjects' ability in understanding the 3-D factors influencing temporal organization, as well as providing them with experience in learning about the types of evidence that are critical in reconstructing a transformational sequence.

  17. Occupational Cohort Time Scales

    PubMed Central

    Roth, H. Daniel

    2015-01-01

    Purpose: This study explores how highly correlated time variables (occupational cohort time scales) contribute to confounding and ambiguity of interpretation. Methods: Occupational cohort time scales were identified and organized through simple equations of three time scales (relational triads) and the connections between these triads (time scale web). The behavior of the time scales was examined when constraints were imposed on variable ranges and interrelationships. Results: Constraints on a time scale in a triad create high correlations between the other two time scales. These correlations combine with the connections between relational triads to produce association paths. High correlation between time scales leads to ambiguity of interpretation. Conclusions: Understanding the properties of occupational cohort time scales, their relational triads, and the time scale web is helpful in understanding the origins of otherwise obscure confounding bias and ambiguity of interpretation. PMID:25647318

  18. `Geologic time series' of earth surface deformation

    NASA Astrophysics Data System (ADS)

    Friedrich, A. M.

    2004-12-01

    The debate of whether the earth has evolved gradually or by catastrophic change has dominated the geological sciences for many centuries. On a human timescale, the earth appears to be changing slowly except for a few sudden events (singularities) such as earthquakes, floods, or landslides. While these singularities dramatically affect the loss of life or the destruction of habitat locally, they have little effect on the global population growth rate or evolution of the earth's surface. It is also unclear to what degree such events leave their traces in the geologic record. Yet, the earth's surface is changing! For example, rocks that equilibrated at depths of > 30 km below the surface are exposed at high elevations in mountains belts indicating vertical motion (uplift) of tens of kilometers; and rocks that acquired a signature of the earth's magnetic field are found up to hundreds of kilometers from their origin indicating significant horizontal transport along great faults. Whether such long-term motion occurs at the rate indicated by the recurrence interval of singular events, or whether singularities also operate at a higher-order scale ("mega-singularities") are open questions. Attempts to address these questions require time series significantly longer than several recurrence intervals of singularities. For example, for surface rupturing earthquakes (Magnitude > 7) with recurrence intervals ranging from tens to tens of thousands of years, observation periods on the order of thousands of years to a million years would be needed. However, few if any of the presently available measurement methods provide both the necessary resolution and "recording duration." While paleoseismic methods have the appropriate spatial and temporal resolution, data collection along most faults has been limited to the last one or two earthquakes. Geologic and geomorphic measurements may record long-term changes in fault slip, but only provide rates averaged over many recurrence

  19. Impact cratering through geologic time

    USGS Publications Warehouse

    Shoemaker, E.M.; Shoemaker, C.S.

    1998-01-01

    New data on lunar craters and recent discoveries about craters on Earth permit a reassessment of the bombardment history of Earth over the last 3.2 billion years. The combined lunar and terrestrial crater records suggest that the long-term average rate of production of craters larger than 20 km in diameter has increased, perhaps by as much as 60%, in the last 100 to 200 million years. Production of craters larger than 70 km in diameter may have increased, in the same time interval, by a factor of five or more over the average for the preceding three billion years. A large increase in the flux of long-period comets appears to be the most likely explanation for such a long-term increase in the cratering rate. Two large craters, in particular, appear to be associated with a comet shower that occurred about 35.5 million years ago. The infall of cosmic dust, as traced by 3He in deep sea sediments, and the ages of large craters, impact glass horizons, and other stratigraphic markers of large impacts seem to be approximately correlated with the estimated times of passage of the Sun through the galactic plane, at least for the last 65 million years. Those are predicted times for an increased near-Earth flux of comets from the Oort Cloud induced by the combined effects of galactic tidal perturbations and encounters of the Sun with passing stars. Long-term changes in the average comet flux may be related to changes in the amplitude of the z-motion of the Sun perpendicular to the galactic plane or to stripping of the outer Oort cloud by encounters with large passing stars, followed by restoration from the inner Oort cloud reservoir.

  20. Geologic time: The age of the Earth

    USGS Publications Warehouse

    Newman, William L.

    1977-01-01

    The Earth is very old 4 1/2 billion years or more according to recent estimates. This vast span of time, called geologic time by earth scientists and believed by some to reach back to the birth of the Solar System, is difficult if not impossible to comprehend in the familiar time units of months and years, or even centuries. How then do scientists reckon geologic time, and why do they believe the Earth is so old? A great part of the secret of the Earth's age is locked up in its rocks, and man's centuries-old search for the key led to the beginning and nourished the growth of geologic science.

  1. Once in a Million Years: Teaching Geologic Time

    ERIC Educational Resources Information Center

    Lewis, Susan E.; Lampe, Kristen A.; Lloyd, Andrew J.

    2005-01-01

    The authors advocate that students frequently lack fundamental numerical literacy on the order of millions or billions, and that this comprehension is critical to grasping key evolutionary concepts related to the geologic time scale, the origin and diversification of life on earth, and other concepts such as the national debt, human population…

  2. Heterogeneity and Scaling in Geologic Media

    SciTech Connect

    Gregory N. Boitnott; Gilles Y. Bussod; Paul N. Hagin; Stephen R. Brown

    2005-04-18

    The accurate characterization and remediation of contaminated subsurface environments requires the detailed knowledge of subsurface structures and flow paths. Enormous resources are invested in scoping and characterizing sites using core sampling, 3-D geophysical surveys, well tests, etc.... Unfortunately, much of the information acquired is lost to compromises and simplifications made in constructing numerical grids for the simulators used to predict flow and transport from the contaminated area to the accessible environment. In rocks and soils, the bulk geophysical and transport properties of the matrix and of fracture systems are determined by the juxtaposition of geometric features at many length scales. In the interest of computational efficiency, recognized heterogeneities are simplified, averaged out, or entirely ignored in spite of recent studies that recognize that: (1) Structural and lithologic heterogeneities exist on all scales in rocks. (2) Small heterogeneities influence, and can control the physical and chemical properties of rocks. In this work we propose a physically based approach for the description and treatment of heterogeneities, that highlights the use of laboratory equipment designed to measure the effect on physical properties of fine scale heterogeneities observed in rocks and soils. We then discuss the development of an integration methodology that uses these measurements to develop and upscale flow and transport models. Predictive simulations are 'calibrated' to the measured heterogeneity data, and subsequently upscaled in a way that is consistent with the transport physics and the efficient use of environmental geophysics. This methodology provides a more accurate interpretation and representation of the subsurface for both environmental engineering and remediation. We show through examples, (i) the important influence of even subtle heterogeneity in the interpreting of geophysical data, and (ii) how physically based upscaling can lead

  3. A Novel Intermediate Complexity box Model (ICBM) for Efficiently Simulating Marine C,N,P,O,S Biogeochemistry Over Geologic Time Scales: Applications for OAE Research

    NASA Astrophysics Data System (ADS)

    Romaniello, S. J.; Derry, L. A.

    2006-12-01

    Global marine redox conditions and marine nutrient status are tightly coupled on geologic timescales. Hypotheses that attempt to explain the occurrence of OAEs and/or the widespread deposition of organic-rich sediments must be dynamically plausible when viewed from the perspective of each of the major biological elements—C,N,P,O, and S. We present a new intermediate complexity box model (ICBM) capable of efficiently examining the coupled interactions of these cycles for a wide range of paleooceanographic hypotheses. Our ICBM fills a unique niche as a compromise between simple box models and more complicated EMICs and OGCMs. For computational speed, we employ a simple circulation model designed to avoid the pitfalls of early 2-3 box ocean models. In exchange, we represent the coupled major element cycles in considerable detail. This enables the biogeochemical submodel to simulate biological and chemical processes over a wide range of redox conditions, while providing efficient integration (1 My/hr). By prescribing simple representations of modern circulation and mixing, we are able to generate characteristic pelagic nutrient profiles and budgets for both the Global Ocean and the Black Sea, without changing the underlying biogeochemical model. We will present results from the simulation of several common explanations for OAEs, and discuss numerical estimates of the sensitivity and feedbacks in these hypothetical systems. Special emphasis will be placed on the interactions between global primary production, dissolved oxygen, nitrogen fixation, and anammox /denitrification.

  4. Evaluating the effects of terrestrial ecosystems, climate and carbon dioxide on weathering over geological time: a global-scale process-based approach.

    PubMed

    Taylor, Lyla L; Banwart, Steve A; Valdes, Paul J; Leake, Jonathan R; Beerling, David J

    2012-02-19

    Global weathering of calcium and magnesium silicate rocks provides the long-term sink for atmospheric carbon dioxide (CO(2)) on a timescale of millions of years by causing precipitation of calcium carbonates on the seafloor. Catchment-scale field studies consistently indicate that vegetation increases silicate rock weathering, but incorporating the effects of trees and fungal symbionts into geochemical carbon cycle models has relied upon simple empirical scaling functions. Here, we describe the development and application of a process-based approach to deriving quantitative estimates of weathering by plant roots, associated symbiotic mycorrhizal fungi and climate. Our approach accounts for the influence of terrestrial primary productivity via nutrient uptake on soil chemistry and mineral weathering, driven by simulations using a dynamic global vegetation model coupled to an ocean-atmosphere general circulation model of the Earth's climate. The strategy is successfully validated against observations of weathering in watersheds around the world, indicating that it may have some utility when extrapolated into the past. When applied to a suite of six global simulations from 215 to 50 Ma, we find significantly larger effects over the past 220 Myr relative to the present day. Vegetation and mycorrhizal fungi enhanced climate-driven weathering by a factor of up to 2. Overall, we demonstrate a more realistic process-based treatment of plant fungal-geosphere interactions at the global scale, which constitutes a first step towards developing 'next-generation' geochemical models. PMID:22232768

  5. Evaluating the effects of terrestrial ecosystems, climate and carbon dioxide on weathering over geological time: a global-scale process-based approach

    PubMed Central

    Taylor, Lyla L.; Banwart, Steve A.; Valdes, Paul J.; Leake, Jonathan R.; Beerling, David J.

    2012-01-01

    Global weathering of calcium and magnesium silicate rocks provides the long-term sink for atmospheric carbon dioxide (CO2) on a timescale of millions of years by causing precipitation of calcium carbonates on the seafloor. Catchment-scale field studies consistently indicate that vegetation increases silicate rock weathering, but incorporating the effects of trees and fungal symbionts into geochemical carbon cycle models has relied upon simple empirical scaling functions. Here, we describe the development and application of a process-based approach to deriving quantitative estimates of weathering by plant roots, associated symbiotic mycorrhizal fungi and climate. Our approach accounts for the influence of terrestrial primary productivity via nutrient uptake on soil chemistry and mineral weathering, driven by simulations using a dynamic global vegetation model coupled to an ocean–atmosphere general circulation model of the Earth's climate. The strategy is successfully validated against observations of weathering in watersheds around the world, indicating that it may have some utility when extrapolated into the past. When applied to a suite of six global simulations from 215 to 50 Ma, we find significantly larger effects over the past 220 Myr relative to the present day. Vegetation and mycorrhizal fungi enhanced climate-driven weathering by a factor of up to 2. Overall, we demonstrate a more realistic process-based treatment of plant fungal–geosphere interactions at the global scale, which constitutes a first step towards developing ‘next-generation’ geochemical models. PMID:22232768

  6. Geological Time on Display in Arabia Terra

    NASA Technical Reports Server (NTRS)

    2002-01-01

    [figure removed for brevity, see original site]

    This scene from the dust covered plains of eastern Arabia Terra portrays a range of geological time. Three craters at the center of the image capture some of this range. Two have the classic bowl-shape of small, relatively recent craters while the one just to the north has seen much more history. Its rim has been scoured away by erosion and its floor has been filled in by material likely of a sedimentary nature. The channels that wind through the scene may be the oldest features present while the relatively dark streaks scattered about could have been produced in the past few years or even months as winds remove a layer of dust to reveal darker material below.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  7. Geological Interpretation of PSInSAR Data at Regional Scale

    PubMed Central

    Meisina, Claudia; Zucca, Francesco; Notti, Davide; Colombo, Alessio; Cucchi, Anselmo; Savio, Giuliano; Giannico, Chiara; Bianchi, Marco

    2008-01-01

    Results of a PSInSAR™ project carried out by the Regional Agency for Environmental Protection (ARPA) in Piemonte Region (Northern Italy) are presented and discussed. A methodology is proposed for the interpretation of the PSInSAR™ data at the regional scale, easy to use by the public administrations and by civil protection authorities. Potential and limitations of the PSInSAR™ technique for ground movement detection on a regional scale and monitoring are then estimated in relationship with different geological processes and various geological environments.

  8. Interpretation of time domain electromagnetic soundings near geological contacts

    SciTech Connect

    Wilt, M.J.

    1991-12-01

    Lateral changes in geology pose a serious problem in data interpretation for any surface geophysical method. Although many geophysical techniques are designed to probe vertically, the source signal invariably spreads laterally, so any lateral variations in geology will affect the measurements and interpretation. This problem is particularly acute for controlled source electromagnetic soundings because only a few techniques are available to interpret the data if lateral effects are present. In this thesis we examine the effects of geological contacts for the time domain electromagnetic sounding method (TDEM). Using two simple two-dimensional models, the truncated thin-sheet and the quarter-space, we examine the system response for several commonly used TDEM sounding configurations. For each system we determine the sensitivity to the contact, establish how to the contact anomaly may be distinguished from other anomalies and, when feasible, develop methods for interpreting the contact geometry and for stripping the contact anomaly from the observed data. Since no numerical models were available when this work was started, data were collected using scale models with a system designed at the University of California at Berkeley. The models were assembled within a table-top modeling tank from sheets or blocks of metal using air or mercury as a host medium. Data were collected with a computer-controlled acquisition system.

  9. Scaling in geology: landforms and earthquakes.

    PubMed Central

    Turcotte, D L

    1995-01-01

    Landforms and earthquakes appear to be extremely complex; yet, there is order in the complexity. Both satisfy fractal statistics in a variety of ways. A basic question is whether the fractal behavior is due to scale invariance or is the signature of a broadly applicable class of physical processes. Both landscape evolution and regional seismicity appear to be examples of self-organized critical phenomena. A variety of statistical models have been proposed to model landforms, including diffusion-limited aggregation, self-avoiding percolation, and cellular automata. Many authors have studied the behavior of multiple slider-block models, both in terms of the rupture of a fault to generate an earthquake and in terms of the interactions between faults associated with regional seismicity. The slider-block models exhibit a remarkably rich spectrum of behavior; two slider blocks can exhibit low-order chaotic behavior. Large numbers of slider blocks clearly exhibit self-organized critical behavior. Images Fig. 6 PMID:11607562

  10. Geological Time, Biological Events and the Learning Transfer Problem

    ERIC Educational Resources Information Center

    Johnson, Claudia C.; Middendorf, Joan; Rehrey, George; Dalkilic, Mehmet M.; Cassidy, Keely

    2014-01-01

    Comprehension of geologic time does not come easily, especially for students who are studying the earth sciences for the first time. This project investigated the potential success of two teaching interventions that were designed to help non-science majors enrolled in an introductory geology class gain a richer conceptual understanding of the…

  11. Will Somebody do the Dishes? Weathering Analogies, Geologic Processes and Geologic Time

    NASA Astrophysics Data System (ADS)

    Stelling, P.; Wuotila, S.; Giuliani, M.

    2006-12-01

    , such as Mt. Rainier or the Grand Canyon. In the end, students completing this project gain an understanding of how geologic processes work, the time scales required, the differences between analogies and the real thing, and arguably the most important aspect, a best-practices approach to doing the dishes.

  12. Cognitive Factors Affecting Student Understanding of Geologic Time.

    ERIC Educational Resources Information Center

    Dodick, Jeff; Orion, Nir

    2003-01-01

    Presents a model that describes how students reconstruct geological transformations over time. Defines the critical factors influencing reconstructive thinking: (1) the transformation scheme, which influences the other diachronic schemes; (2) knowledge of geological processes; and (3) extracognitive factors. (Author/KHR)

  13. South Atlantic Spreading Velocities and Time Scales

    NASA Astrophysics Data System (ADS)

    Clark, S. R.; Smethurst, M. A.; Bianchi, M. C.

    2013-12-01

    Plate reconstructions based on hierarchical spherical rotations have been around for many years. For the breakup of Pangea and Gondwana, these reconstructions are based on two major sources: magnetic isochrons and geological evidence for the onset of rifting and the tightness of the fit between continents. These reconstructions imply spreading velocities and it is the changes in velocities that can be used to probe questions of the forces moving plates around. In order to calculate the velocities correctly though, the importance of the choice of geologic time scale is often ignored. In this talk, we focus on the South Atlantic and calculate the spreading velocity errors implied by the choice of time scale for three major epochs: the Cenozoic and Late Mesozoic, the Cretaceous Quiet Zone and the Late Cretaceous to the Early Jurassic. In addition, we report the spreading velocities implied through these phases by various available magnetic isochron-derived reconstructions and the geological fits for South America and Africa used by large scale global reconstruction as well as in recent papers. Finally, we will highlight the implications for the choice of the mantle reference frame on African plate velocities.

  14. Time Scales: Terrestrial

    NASA Astrophysics Data System (ADS)

    Petit, G.; Murdin, P.

    2000-11-01

    Terrestrial time is at present derived from atomic clocks. The SI second, the unit of time of the international system of units, has been defined since 1967 in terms of a hyperfine transition of the cesium atom and the best primary frequency standards now realize it with a relative uncertainty of a few parts in 1015, which makes it the most accurately measurable physical quantity. INTERNATIONAL A...

  15. Multi-scale Geological Outcrop Visualisation: Using Gigapan and Photosynth in Fieldwork-related Geology Teaching

    NASA Astrophysics Data System (ADS)

    Stimpson, Ian; Gertisser, Ralf; Montenari, Michael; O'Driscoll, Brian

    2010-05-01

    An increasing proportion of geology (and other fieldwork-related discipline) students are mobility impaired. This is partially due to the widening access agenda and the acceptance of increased numbers of students with severe medical disabilities. In the UK, the expectation of "The Special Educational Needs and Disabilities Act (2001)" (SENDA) and "The Higher Education Quality Assurance Agency" (QAA) is that institutions should, wherever possible, provide alternative experiences where comparable opportunities are available which satisfy the learning outcomes. In order to provide this alternative experience, the ways in which students observe and learn from geology in the field need to be resembled closely by, for example, viewing outcrops at different scales and from different perspectives. Whilst a series of still images at different distances could be taken, students need to be able to decide where to look in detail and 'move around' the outcrop. The Gigapan project is a website and supporting software that allows high-resolution megapixel photographic images to be combined to make gigapixel panoramas which can then be explored at many scales by zooming and panning. Photosynth is a similar project where a number of different digital photographs are combined into a 3D model in which the user can move around. Here, we show examples of both projects, which have been successfully implemented in geology teaching related to a residential undergraduate field course to classic geological areas in Pembrokeshire, South Wales. In addition to providing an alternative learning experience for mobility-impaired students on the fieldtrip, these resources could also be used for non-impaired students where circumstances such as bad weather prevents the whole cohort from visiting a key exposure on a field course. They would also allow a 'virtual' visit of exposures that are inaccessible and may be a useful learning tool for preparing students for a forthcoming field course.

  16. Understanding Evolutionary Change within the Framework of Geological Time

    ERIC Educational Resources Information Center

    Dodick, Jeff

    2007-01-01

    This paper focuses on a learning strategy designed to overcome students' difficulty in understanding evolutionary change within the framework of geological time. Incorporated into the learning program "From Dinosaurs to Darwin: Evolution from the Perspective of Time," this strategy consists of four scaffolded investigations in which students…

  17. Geologic history of Siletzia, a large igneous province in the Oregon and Washington Coast Range: correlation to the geomagnetic polarity time scale and implications for a long-lived Yellowstone hotspot

    USGS Publications Warehouse

    Wells, Ray; Bukry, David; Friedman, Richard; Pyle, Douglas; Duncan, Robert; Haeussler, Peter; Wooden, Joe

    2014-01-01

    Siletzia is a basaltic Paleocene and Eocene large igneous province in coastal Oregon, Washington, and southern Vancouver Island that was accreted to North America in the early Eocene. New U-Pb magmatic, detrital zircon, and 40Ar/39Ar ages constrained by detailed field mapping, global nannoplankton zones, and magnetic polarities allow correlation of the volcanics with the 2012 geologic time scale. The data show that Siletzia was rapidly erupted 56–49 Ma, during the Chron 25–22 plate reorganization in the northeast Pacific basin. Accretion was completed between 51 and 49 Ma in Oregon, based on CP11 (CP—Coccolith Paleogene zone) coccoliths in strata overlying onlapping continental sediments. Magmatism continued in the northern Oregon Coast Range until ca. 46 Ma with the emplacement of a regional sill complex during or shortly after accretion. Isotopic signatures similar to early Columbia River basalts, the great crustal thickness of Siletzia in Oregon, rapid eruption, and timing of accretion are consistent with offshore formation as an oceanic plateau. Approximately 8 m.y. after accretion, margin parallel extension of the forearc, emplacement of regional dike swarms, and renewed magmatism of the Tillamook episode peaked at 41.6 Ma (CP zone 14a; Chron 19r). We examine the origin of Siletzia and consider the possible role of a long-lived Yellowstone hotspot using the reconstruction in GPlates, an open source plate model. In most hotspot reference frames, the Yellowstone hotspot (YHS) is on or near an inferred northeast-striking Kula-Farallon and/or Resurrection-Farallon ridge between 60 and 50 Ma. In this configuration, the YHS could have provided a 56–49 Ma source on the Farallon plate for Siletzia, which accreted to North America by 50 Ma. A sister plateau, the Eocene basalt basement of the Yakutat terrane, now in Alaska, formed contemporaneously on the adjacent Kula (or Resurrection) plate and accreted to coastal British Columbia at about the same time

  18. Experimental and geological approaches to elucidate chemical change in sporopollenin over geological time

    NASA Astrophysics Data System (ADS)

    Fraser, Wesley; Lomax, Barry; Jardine, Phillip

    2016-04-01

    Sporopollenin is the primary biopolymer comprising the walls of sporomorphs (pollen and spores), both in extant material and found within the fossil record. Maturation processes associated with sedimentation and burial over geological timescales have long been considered to dramatically alter the chemical nature of organic material, most notably via oxidation. Here we present experimental data derived from simulated maturation, analyses of Carboniferous fossil material, and modern-day material. Our data demonstrate the core structure of sporopollenin undergoes only minor chemical adjustments at lower grades of maturation, with the over-riding chemical signature remaining identifiable as that of sporopollenin, showing strong resemblance to modern material. This modern signature can, in specific cases be preserved in the geological record, demonstrated by the near-pristine chemical composition of megaspores preserved in cave deposits of Pennsylvanian age (Carboniferous, c. 310 Ma). Conversely, the labile component associated with sporopollenin is found to readily defunctionalise and repolymerise to generate a new polyalkyl macromolecule in situ. The labile component is shown to be held in position via ester linkages; a common chemical feature observed in extant sporopollenin. This combined experimental and geological investigation provides insights into i) the preservation of chemical signatures within the fossil record, ii) considerations for sample preparation when undertaking chemical analysis of fossil sporomorphs, and iii) the long-term evolutionary stasis of sporopollenin, spanning geological time.

  19. Geology

    SciTech Connect

    Reidel, Stephen P.

    2008-01-17

    This chapter summarizes the geology of the single-shell tank (SST) farms in the context of the region’s geologic history. This chapter is based on the information in the geology data package for the SST waste management areas and SST RFI Appendix E, which builds upon previous reports on the tank farm geology and Integrated Disposal Facility geology with information available after those reports were published.

  20. Scaling filtering and multiplicative cascade information integration techniques for geological, geophysical and geochemical data processing and geological feature recognition

    NASA Astrophysics Data System (ADS)

    Cheng, Q.

    2013-12-01

    This paper introduces several techniques recently developed based on the concepts of multiplicative cascade processes and multifractals for processing exploration geochemical and geophysical data for recognition of geological features and delineation of target areas for undiscovered mineral deposits. From a nonlinear point of view extreme geo-processes such as cloud formation, rainfall, hurricanes, flooding, landslides, earthquakes, igneous activities, tectonics and mineralization often show singular property that they may result in anomalous amounts of energy release or mass accumulation that generally are confined to narrow intervals in space or time. The end products of these non-linear processes have in common that they can be modeled as fractals or multifractals. Here we show that the three fundamental concepts of scaling in the context of multifractals: singularity, self-similarity and fractal dimension spectrum, make multifractal theory and methods useful for geochemical and geophysical data processing for general purposes of geological features recognition. These methods include: a local singularity analysis based on a area-density (C-A) multifractal model used as a scaling high-pass filtering technique capable of extracting weak signals caused by buried geological features; a suite of multifractal filtering techniques based on spectrum density - area (S-A) multifractal models implemented in various domain including frequency domain can be used for unmixing geochemical or geophysical fields according to distinct generalized self-similarities characterized in certain domain; and multiplicative cascade processes for integration of diverse evidential layers of information for prediction of point events such as location of mineral deposits. It is demonstrated by several case studies involving Fe, Sn, Mo-Ag and Mo-W mineral deposits that singularity method can be utilized to process stream sediment/soil geochemical data and gravity/aeromagnetic data as high

  1. Porphyry copper deposit tract definition - A global analysis comparing geologic map scales

    USGS Publications Warehouse

    Raines, G.L.; Connors, K.A.; Chorlton, L.B.

    2007-01-01

    Geologic maps are a fundamental data source used to define mineral-resource potential tracts for the first step of a mineral resource assessment. Further, it is generally believed that the scale of the geologic map is a critical consideration. Previously published research has demonstrated that the U.S. Geological Survey porphyry tracts identified for the United States, which are based on 1:500,000-scale geology and larger scale data and published at 1:1,000,000 scale, can be approximated using a more generalized 1:2,500,000-scale geologic map. Comparison of the USGS porphyry tracts for the United States with weights-of-evidence models made using a 1:10,000,000-scale geologic map, which was made for petroleum applications, and a 1:35,000,000-scale geologic map, which was created as context for the distribution of porphyry deposits, demonstrates that, again, the USGS US porphyry tracts identified are similar to tracts defined on features from these small scale maps. In fact, the results using the 1:35,000,000-scale map show a slightly higher correlation with the USGS US tract definition, probably because the conceptual context for this small-scale map is more appropriate for porphyry tract definition than either of the other maps. This finding demonstrates that geologic maps are conceptual maps. The map information shown in each map is selected and generalized for the map to display the concepts deemed important for the map maker's purpose. Some geologic maps of small scale prove to be useful for regional mineral-resource tract definition, despite the decrease in spatial accuracy with decreasing scale. The utility of a particular geologic map for a particular application is critically dependent on the alignment of the intention of the map maker with the application. ?? International Association for Mathematical Geology 2007.

  2. Predation through geological time: evidence from gastropod shell repair.

    PubMed

    Vermeij, G J; Schindel, D E; Zipser, E

    1981-11-27

    Warm-water marine gastropods from soft-bottom habitats show an increase in the incidence of breakage-resistant shell characteristics over geological time. The hypothesis that breakage became a more important component of selection in the middle of the Mesozoic Era is supported by the finding that frequencies of breakage-induced shell repair increased from the Pennsylvanian and Triassic periods to the Cretaceous, Miocene, and Recent. PMID:17808668

  3. Linking subsurface temperature and hillslope processes through geologic time

    NASA Astrophysics Data System (ADS)

    Barnhart, Katherine; Anderson, Robert

    2015-04-01

    Many periglacial hillslope processes - physical, chemical, and biological - depend on subsurface temperature and water availability. As the subsurface temperature field varies both in space and through time over many scales up to climate cycles, the dominant processes of mobile regolith production and transport and the rate at which they act will vary. These processes include the chemical weathering of minerals, cracking of rocks through frost action and tree roots, presence and impact of vegetation on soil cohesion, location and activity of burrowing and trampling animals, frost creep, and solifluction. In order to explore the interplay between these processes across a landscape over the geologic timescales on which such landscapes evolve, we explore the effects of slope, aspect, latitude, atmosphere, and time before present on the expected energy balance at the surface of the earth and the resulting subsurface temperature field. We begin by calculating top-of-atmosphere insolation at any time in the Quaternary, honoring the variations in orbit over Milankovitch timescales. We then incorporate spatial and temporal variations in incoming short-wave radiation on sub-daily timescales due to elevation, latitude, aspect, and shading. Outgoing long-wave radiation is taken to depend on the surface temperature and may be modified by allowing back-radiation from the atmosphere. We then solve for the subsurface temperature field using a numerical model that acknowledges depth-varying material properties, water content, and phase change. With these tools we target variations in regolith production and motion over the long timescales on which periglacial hillslopes evolve. We implement a basic parameterization of temperature-dependent chemical and physical weathering linked to mobile regolith generation. We incorporate multiple regolith transport processes including frost heave and creep. Our intention is not to parameterize all operative processes, but to include sufficient

  4. Kilometer-scale Roughness of Geological Units on Mars: Initial Results from MOLA Data

    NASA Astrophysics Data System (ADS)

    Kreslavsky, M. A.; Head, J. W.

    1999-03-01

    Scale dependence of the median slope is studied for a number of geological units. Similarity of km-scale roughness of Vastitas Borealis Formation subunits and the circumpolar mantling deposits suggests similarity of their origin.

  5. A Laboratory Study of Heterogeneity and Scaling in Geologic Media

    NASA Astrophysics Data System (ADS)

    Brown, S.; Boitnott, G.; Bussod, G.; Hagan, P.

    2004-05-01

    In rocks and soils, the bulk geophysical and transport properties of the matrix and of fracture systems are determined by the juxtaposition of geometric features at many length scales. For sedimentary materials the length scales are: the pore scale (irregularities in grain surface roughness and cementation), the scale of grain packing faults (and the resulting correlated porosity structures), the scale dominated by sorting or winnowing due to depositional processes, and the scale of geomorphology at the time of deposition. We are studying the heterogeneity and anisotropy in geometry, permeability, and geophysical response from the pore (microscopic), laboratory (mesoscopic), and backyard field (macroscopic) scales. In turn these data are being described and synthesized for development of mathematical models. Eventually, we will perform parameter studies to explore these models in the context of transport in the vadose and saturated zones. We have developed a multi-probe physical properties scanner which allows for the mapping of geophysical properties on a slabbed sample or core. This device allows for detailed study of heterogeneity at those length scales most difficult to quantify using standard field and laboratory practices. The measurement head consists of a variety of probes designed to make local measurements of various properties, including: gas permeability, acoustic velocities (compressional and shear), complex electrical impedance (4 electrode, wide frequency coverage), and ultrasonic reflection (ultrasonic impedance and permeability). We can thus routinely generate detailed geophysical maps of a particular sample. We are testing and modifying these probes as necessary for use on soil samples. As a baseline study we have been characterizing the heterogeneity of a bench-size Berea sandstone block. Berea Sandstone has long been regarded as a laboratory standard in rock properties studies, owing to its uniformity and ``typical'' physical properties. We find

  6. Time scales in cognitive neuroscience

    PubMed Central

    Papo, David

    2013-01-01

    Cognitive neuroscience boils down to describing the ways in which cognitive function results from brain activity. In turn, brain activity shows complex fluctuations, with structure at many spatio-temporal scales. Exactly how cognitive function inherits the physical dimensions of neural activity, though, is highly non-trivial, and so are generally the corresponding dimensions of cognitive phenomena. As for any physical phenomenon, when studying cognitive function, the first conceptual step should be that of establishing its dimensions. Here, we provide a systematic presentation of the temporal aspects of task-related brain activity, from the smallest scale of the brain imaging technique's resolution, to the observation time of a given experiment, through the characteristic time scales of the process under study. We first review some standard assumptions on the temporal scales of cognitive function. In spite of their general use, these assumptions hold true to a high degree of approximation for many cognitive (viz. fast perceptual) processes, but have their limitations for other ones (e.g., thinking or reasoning). We define in a rigorous way the temporal quantifiers of cognition at all scales, and illustrate how they qualitatively vary as a function of the properties of the cognitive process under study. We propose that each phenomenon should be approached with its own set of theoretical, methodological and analytical tools. In particular, we show that when treating cognitive processes such as thinking or reasoning, complex properties of ongoing brain activity, which can be drastically simplified when considering fast (e.g., perceptual) processes, start playing a major role, and not only characterize the temporal properties of task-related brain activity, but also determine the conditions for proper observation of the phenomena. Finally, some implications on the design of experiments, data analyses, and the choice of recording parameters are discussed. PMID:23626578

  7. Monitoring CO2 invasion processes at the pore scale using geological labs on chip.

    PubMed

    Morais, S; Liu, N; Diouf, A; Bernard, D; Lecoutre, C; Garrabos, Y; Marre, S

    2016-09-21

    In order to investigate at the pore scale the mechanisms involved during CO2 injection in a water saturated pore network, a series of displacement experiments is reported using high pressure micromodels (geological labs on chip - GLoCs) working under real geological conditions (25 < T (°C) < 75 and 4.5 < p (MPa) < 8). The experiments were focused on the influence of three experimental parameters: (i) the p, T conditions, (ii) the injection flow rates and (iii) the pore network characteristics. By using on-chip optical characterization and imaging approaches, the CO2 saturation curves as a function of either time or the number of pore volume injected were determined. Three main mechanisms were observed during CO2 injection, namely, invasion, percolation and drying, which are discussed in this paper. Interestingly, besides conventional mechanisms, two counterintuitive situations were observed during the invasion and drying processes. PMID:27494277

  8. Testing the hydrologic utility of geologic frameworks for extrapolating hydraulic properties across large scales

    NASA Astrophysics Data System (ADS)

    Mirus, B. B.; Halford, K. J.; Sweetkind, D. S.; Fenelon, J.

    2014-12-01

    The utility of geologic frameworks for extrapolating hydraulic conductivities to length scales that are commensurate with hydraulic data has been assessed at the Nevada National Security Site in highly-faulted volcanic rocks. Observed drawdowns from eight, large-scale, aquifer tests on Pahute Mesa provided the necessary constraints to test assumed relations between hydraulic conductivity and interpretations of the geology. The investigated volume of rock encompassed about 40 cubic miles where drawdowns were detected more than 2 mi from pumping wells and traversed major fault structures. Five sets of hydraulic conductivities at about 500 pilot points were estimated by simultaneously interpreting all aquifer tests with a different geologic framework for each set. Each geologic framework was incorporated as prior information that assumed homogeneous hydraulic conductivities within each geologic unit. Complexity of the geologic frameworks ranged from an undifferentiated mass of rock with a single unit to 14 unique geologic units. Analysis of the model calibrations showed that a maximum of four geologic units could be differentiated where each was hydraulically unique as defined by the mean and standard deviation of log-hydraulic conductivity. Consistency of hydraulic property estimates within extents of investigation and effects of geologic frameworks on extrapolation were evaluated qualitatively with maps of transmissivity. Distributions of transmissivity were similar within the investigated extents regardless of geologic framework except for a transmissive streak along a fault in the Fault-Structure framework. Extrapolation was affected by underlying geologic frameworks where the variability of transmissivity increased as the number of units increased.

  9. Approaches for the accurate definition of geological time boundaries

    NASA Astrophysics Data System (ADS)

    Schaltegger, Urs; Baresel, Björn; Ovtcharova, Maria; Goudemand, Nicolas; Bucher, Hugo

    2015-04-01

    Which strategies lead to the most precise and accurate date of a given geological boundary? Geological units are usually defined by the occurrence of characteristic taxa and hence boundaries between these geological units correspond to dramatic faunal and/or floral turnovers and they are primarily defined using first or last occurrences of index species, or ideally by the separation interval between two consecutive, characteristic associations of fossil taxa. These boundaries need to be defined in a way that enables their worldwide recognition and correlation across different stratigraphic successions, using tools as different as bio-, magneto-, and chemo-stratigraphy, and astrochronology. Sedimentary sequences can be dated in numerical terms by applying high-precision chemical-abrasion, isotope-dilution, thermal-ionization mass spectrometry (CA-ID-TIMS) U-Pb age determination to zircon (ZrSiO4) in intercalated volcanic ashes. But, though volcanic activity is common in geological history, ashes are not necessarily close to the boundary we would like to date precisely and accurately. In addition, U-Pb zircon data sets may be very complex and difficult to interpret in terms of the age of ash deposition. To overcome these difficulties we use a multi-proxy approach we applied to the precise and accurate dating of the Permo-Triassic and Early-Middle Triassic boundaries in South China. a) Dense sampling of ashes across the critical time interval and a sufficiently large number of analysed zircons per ash sample can guarantee the recognition of all system complexities. Geochronological datasets from U-Pb dating of volcanic zircon may indeed combine effects of i) post-crystallization Pb loss from percolation of hydrothermal fluids (even using chemical abrasion), with ii) age dispersion from prolonged residence of earlier crystallized zircon in the magmatic system. As a result, U-Pb dates of individual zircons are both apparently younger and older than the depositional age

  10. Students' Understanding of Large Numbers as a Key Factor in Their Understanding of Geologic Time

    ERIC Educational Resources Information Center

    Cheek, Kim A.

    2012-01-01

    An understanding of geologic time is comprised of 2 facets. Events in Earth's history can be placed in relative and absolute temporal succession on a vast timescale. Rates of geologic processes vary widely, and some occur over time periods well outside human experience. Several factors likely contribute to an understanding of geologic time, one of…

  11. Quantitative analysis of scale of aeromagnetic data raises questions about geologic-map scale

    USGS Publications Warehouse

    Nykanen, V.; Raines, G.L.

    2006-01-01

    A recently published study has shown that small-scale geologic map data can reproduce mineral assessments made with considerably larger scale data. This result contradicts conventional wisdom about the importance of scale in mineral exploration, at least for regional studies. In order to formally investigate aspects of scale, a weights-of-evidence analysis using known gold occurrences and deposits in the Central Lapland Greenstone Belt of Finland as training sites provided a test of the predictive power of the aeromagnetic data. These orogenic-mesothermal-type gold occurrences and deposits have strong lithologic and structural controls associated with long (up to several kilometers), narrow (up to hundreds of meters) hydrothermal alteration zones with associated magnetic lows. The aeromagnetic data were processed using conventional geophysical methods of successive upward continuation simulating terrane clearance or 'flight height' from the original 30 m to an artificial 2000 m. The analyses show, as expected, that the predictive power of aeromagnetic data, as measured by the weights-of-evidence contrast, decreases with increasing flight height. Interestingly, the Moran autocorrelation of aeromagnetic data representing differing flight height, that is spatial scales, decreases with decreasing resolution of source data. The Moran autocorrelation coefficient scems to be another measure of the quality of the aeromagnetic data for predicting exploration targets. ?? Springer Science+Business Media, LLC 2007.

  12. Crustal-scale geological and thermal models of the Beaufort-Mackenzie Basin, Arctic Canada

    NASA Astrophysics Data System (ADS)

    Sippel, Judith; Scheck-Wenderoth, Magdalena; Kröger, Karsten; Lewerenz, Björn

    2010-05-01

    The Beaufort-Mackenzie Basin is a petroliferous province in northwest Arctic Canada and one of the best-known segments of the Arctic Ocean margin due to decades of exploration. Our study is part of the programme MOM (Methane On the Move), which aims to quantify the methane contribution from natural petroleum systems to the atmosphere over geological times. Models reflecting the potential of a sedimentary basin to release methane require well-assessed boundary conditions such as the crustal structure and large-scale temperature variation. We focus on the crustal-scale thermal field of the Beaufort-Mackenzie Basin. This Basin has formed on a post-rift, continental margin which, during the Late Cretaceous and Tertiary, developed into the foreland of the North American Cordilleran foldbelt providing space for the accumulation of up to 16 km of foreland deposits. We present a 3D geological model which integrates the present topography, depth maps of Upper Cretaceous and Tertiary horizons (Kroeger et al., 2008, 2009), tops of formations derived from interpreted 2D reflection seismic lines and 284 boreholes (released by the National Energy Board of Canada), and the sequence stratigraphic framework established by previous studies (e.g. Dixon et al., 1996). To determine the position and geometry of the crust-mantle boundary, an isostatic calculation (Airýs model) is applied to the geological model. We present different crustal-scale models combining isostatic modelling, published deep reflection and refraction seismic lines (e.g. Stephenson et al., 1994; O'Leary et al., 1995), and calculations of the 3D conductive thermal field. References: Dixon, J., 1996. Geological Atlas of the Beaufort-Mackenzie Area, Geological Survey of Canada Miscellaneous Report, 59, Ottawa, 173 pp. Kroeger, K.F., Ondrak, R., di Primio, R. and Horsfield, B., 2008. A three-dimensional insight into the Mackenzie Basin (Canada): Implications for the thermal history and hydrocarbon generation potential

  13. Geology

    NASA Technical Reports Server (NTRS)

    Stewart, R. K.; Sabins, F. F., Jr.; Rowan, L. C.; Short, N. M.

    1975-01-01

    Papers from private industry reporting applications of remote sensing to oil and gas exploration were presented. Digitally processed LANDSAT images were successfully employed in several geologic interpretations. A growing interest in digital image processing among the geologic user community was shown. The papers covered a wide geographic range and a wide technical and application range. Topics included: (1) oil and gas exploration, by use of radar and multisensor studies as well as by use of LANDSAT imagery or LANDSAT digital data, (2) mineral exploration, by mapping from LANDSAT and Skylab imagery and by LANDSAT digital processing, (3) geothermal energy studies with Skylab imagery, (4) environmental and engineering geology, by use of radar or LANDSAT and Skylab imagery, (5) regional mapping and interpretation, and digital and spectral methods.

  14. Stellar Evolution and its Relations to Geological Time

    NASA Astrophysics Data System (ADS)

    Croll, James

    2012-05-01

    Part I. The Impact Theory of Stellar Evolution: Consideration of the facts which support the theory, and of the light which the theory appears to cast upon the facts; 1. Probable origin of meteorites; 2. Motion of the stars, how of such different velocities, and always in straight lines; 3. Motion of the stars not due to their mutual attractions; 4. Probable origin of comets; 5. Nebulae; 6. Binary systems; 7. Sudden outbursts of stars; 8. Star clusters; 9. Age of the sun's heat - a crucial test; Part II. Evidence in Support of the Theory from the Age of the Sun's Heat: Testimony of geology and biology as to the age of the sun's heat; Testimony of geology - method employed; The average rate of denudation in the past probably not much greater than at the present; How the method has been applied; Method as applied by Professor Haughton; Method as applied by Mr Alfred R. Wallace; Method as applied directly; Evidence from 'faults'; Time required to effect the foregoing amount of denudation; Age of the earth as determined by the date of the glacial epochs; Testimony of biology; Part III. Evidence in Support of the Theory from the Pre-nebular Condition of the Universe: Professor A. Winchell on the pre-nebular condition of matter; Mr Charles Morris on the pre-nebular condition of matter; Sir William R. Grove on the pre-nebular condition of matter; Evolution of the chemical elements, and its relations to stellar evolution; Sir Benjamin Brodie on the pre-nebular condition of matter; Dr T. Sterry Hunt on the pre-nebular condition of matter; Professor Oliver Lodge on the pre-nebular condition of matter; Mr. William Crookes on the pre-nebular condition of matter; Professor F. W. Clarke on the pre-nebular condition of matter; Dr G. Johnstone Stoney on the pre-nebular condition of matter; The impact theory in relation to the foregoing theories of the pre-nebular condition of matter; Index.

  15. Stability of Rasch Scales over Time

    ERIC Educational Resources Information Center

    Taylor, Catherine S.; Lee, Yoonsun

    2010-01-01

    Item response theory (IRT) methods are generally used to create score scales for large-scale tests. Research has shown that IRT scales are stable across groups and over time. Most studies have focused on items that are dichotomously scored. Now Rasch and other IRT models are used to create scales for tests that include polytomously scored items.…

  16. Biotic survival in the cryobiosphere on geological scale: implication for astro/terrestrial biogeoscience

    NASA Astrophysics Data System (ADS)

    Gilichinsky, D.

    2003-04-01

    In current opinion the most fundamental aspect of any environment, the temperature regime, acts as a regulator of all of the physical-chemical reactions and forms the basis of all biological processes. Now hard data indicate the biotic survival over geological periods from subzero temperatures (down to -27oC in permafrost and to -50oC in ice) to positive one in amber and halite. All these very different environments have, nevertheless, common features: complete isolation, stability and waterproof. In such unique physical-chemical complexes, the dehydration of macromolecules and the reorganization of membrane components apparently lead to a considerable decrease or stop of metabolic activity independently of temperature. This allowed the prolonged survival of ancient microbial lineage that realize unknown possibilities of physiological and biochemical adaptation incomparably longer than any other known habitat. The ability of microorganisms to survive on geological scale within the broad limits of natural systems forces us to redefine the spatial and temporal limits of the terrestrial and extraterrestrial biospheres and suggested that universal mechanisms of such adaptation might operate for millions of years. Among new scientific directions formed on this base, the most general is the fundamental question: how long the life might be preserved and what mechanisms could ensure survival? Because the length of lifetime cannot be reproduced, this highlights the natural storages that make possible the observation of the results of biotic survival on geological scale. Of special interest is the interaction of knowledge to understanding of the limits of the deep cold biosphere as a depository of ancient active biosignatures (biogases, biominerals, pigments, lipids, enzymes, proteins, RNA/DNA fragments) and viable cells. The last are the only known a huge mass of organisms that have retained viability over geological periods and upon thawing, renew physiological activity

  17. Scale determinants of fiscal investment in geological exploration: evidence from China.

    PubMed

    Lu, Linna; Lei, Yalin

    2013-01-01

    With the continued growth in demand for mineral resources and China's efforts in increasing investment in geological prospecting, fiscal investment in geological exploration becomes a research hotspot. This paper examines the yearly relationship among fiscal investment in geological exploration of the current term, that of the last term and prices of mining rights over the period 1999-2009. Hines and Catephores' investment acceleration model is applied to describe the scale determinants of fiscal investment in geological exploration which are value-added of mining rights, value of mining rights and fiscal investment in the last term. The results indicate that when value-added of mining rights, value of mining rights or fiscal investment in the last term moves at 1 unit, fiscal investment in the current term will move 0.381, 1.094 or 0.907 units respectively. In order to determine the scale of fiscal investment in geological exploration for the current year, the Chinese government should take fiscal investment in geological exploration for the last year and the capital stock of the previous investments into account. In practice, combination of government fiscal investment in geological exploration with its performance evaluation can create a virtuous circle of capital management mechanism. PMID:24204652

  18. A Long, Long Time Ago: Student Perceptions of Geologic Time Using a 45.6-foot-long Timeline

    NASA Astrophysics Data System (ADS)

    Gehman, J. R.; Johnson, E. A.

    2008-12-01

    In this study we investigated preconceptions of geologic time held by students in five large (50-115 students each) sections of introductory geology and Earth science courses. Students were randomly divided into groups of eleven individuals, and each group was assigned a separate timeline made from a roll of adding machine paper. Students were encouraged to work as a group to place the eleven geological or biological events where they thought they should belong on their timeline based only on their previous knowledge of geologic time. Geologic events included "Oldest Known Earth Rock" and "The Colorado River Begins to Form the Grand Canyon" while biological events included such milestones as "First Fish," "Dinosaurs go Extinct," and "First Modern Humans." Students were asked in an anonymous survey how they decided to place the events on the timeline in this initial exercise. After the eleven event cards were clipped to the timeline and marks were made to record the initial location of each event, students returned to the classroom and were provided with a scale and the correct dates for the events. Each paper timeline was 45.6 ft. long to represent the 4.56 billion years of Earth history (each one-foot-wide floor tile in the hallways outside the classroom equals 100 million years). Student then returned to their timelines and moved the event cards to the correct locations. At the end of the exercise, survey questions and the paper timelines with the markings of the original position of geologic events were collected and compiled. Analysis of the timeline data based on previous knowledge revealed that no group of students arranged all of the events in the proper sequence, although several groups misplaced only two events in relative order. Students consistently placed events further back in time than their correct locations based on absolute age dates. The survey revealed that several student groups used one "old" event such as the "First Dinosaurs Appear" or

  19. Aerobic microbial dolomite at the nanometer scale: Implications for the geologic record

    NASA Astrophysics Data System (ADS)

    Sánchez-Román, Mónica; Vasconcelos, Crisógono; Schmid, Thomas; Dittrich, Maria; McKenzie, Judith A.; Zenobi, Renato; Rivadeneyra, Maria A.

    2008-11-01

    Microbial experiments are the only proven approach to produceexperimental dolomite under Earth's surface conditions. Althoughmicrobial metabolisms are known to induce dolomite precipitationby favoring dolomite growth kinetics, the involvement of microbesin the dolomite nucleation process is poorly understood. Inparticular, the nucleation of microbially mediated dolomiteremains a matter for investigation because the metabolic diversityinvolved in this process has not been fully explored. Hereinwe demonstrate that Halomonas meridiana and Virgibacillus marismortui,two moderately halophilic aerobic bacteria, mediate primaryprecipitation of dolomite at low temperatures (25, 35 °C).This report emphasizes the biomineralogical implications fordolomite formation at the nanometer scale. We describe nucleationof dolomite on nanoglobules in intimate association with thebacterial cell surface. A combination of both laboratory cultureexperiments and natural samples reveals that these nanoglobulestructures may be: (1) the initial step for dolomite nucleation,(2) preserved in the geologic record, and (3) used as microbialtracers through time and/or as a proxy for ancient microbialdolomite, as well as other carbonate minerals.

  20. Introduction to the time scale problem

    SciTech Connect

    Voter, A. F.

    2002-01-01

    As motivation for the symposium on extended-scale atomistic methods, I briefly discuss the time scale problem that plagues molecular dynamics simulations, some promising recent developments for circumventing the problem, and some remaining challenges.

  1. Testing the suitability of geologic frameworks for extrapolating hydraulic properties across regional scales

    NASA Astrophysics Data System (ADS)

    Mirus, Benjamin B.; Halford, Keith; Sweetkind, Don; Fenelon, Joe

    2016-02-01

    The suitability of geologic frameworks for extrapolating hydraulic conductivity (K) to length scales commensurate with hydraulic data is difficult to assess. A novel method is presented for evaluating assumed relations between K and geologic interpretations for regional-scale groundwater modeling. The approach relies on simultaneous interpretation of multiple aquifer tests using alternative geologic frameworks of variable complexity, where each framework is incorporated as prior information that assumes homogeneous K within each model unit. This approach is tested at Pahute Mesa within the Nevada National Security Site (USA), where observed drawdowns from eight aquifer tests in complex, highly faulted volcanic rocks provide the necessary hydraulic constraints. The investigated volume encompasses 40 mi3 (167 km3) where drawdowns traversed major fault structures and were detected more than 2 mi (3.2 km) from pumping wells. Complexity of the five frameworks assessed ranges from an undifferentiated mass of rock with a single unit to 14 distinct geologic units. Results show that only four geologic units can be justified as hydraulically unique for this location. The approach qualitatively evaluates the consistency of hydraulic property estimates within extents of investigation and effects of geologic frameworks on extrapolation. Distributions of transmissivity are similar within the investigated extents irrespective of the geologic framework. In contrast, the extrapolation of hydraulic properties beyond the volume investigated with interfering aquifer tests is strongly affected by the complexity of a given framework. Testing at Pahute Mesa illustrates how this method can be employed to determine the appropriate level of geologic complexity for large-scale groundwater modeling.

  2. Testing the suitability of geologic frameworks for extrapolating hydraulic properties across regional scales

    USGS Publications Warehouse

    Mirus, Benjamin B.; Halford, Keith J.; Sweetkind, Donald; Fenelon, Joseph M.

    2016-01-01

    The suitability of geologic frameworks for extrapolating hydraulic conductivity (K) to length scales commensurate with hydraulic data is difficult to assess. A novel method is presented for evaluating assumed relations between K and geologic interpretations for regional-scale groundwater modeling. The approach relies on simultaneous interpretation of multiple aquifer tests using alternative geologic frameworks of variable complexity, where each framework is incorporated as prior information that assumes homogeneous K within each model unit. This approach is tested at Pahute Mesa within the Nevada National Security Site (USA), where observed drawdowns from eight aquifer tests in complex, highly faulted volcanic rocks provide the necessary hydraulic constraints. The investigated volume encompasses 40 mi3 (167 km3) where drawdowns traversed major fault structures and were detected more than 2 mi (3.2 km) from pumping wells. Complexity of the five frameworks assessed ranges from an undifferentiated mass of rock with a single unit to 14 distinct geologic units. Results show that only four geologic units can be justified as hydraulically unique for this location. The approach qualitatively evaluates the consistency of hydraulic property estimates within extents of investigation and effects of geologic frameworks on extrapolation. Distributions of transmissivity are similar within the investigated extents irrespective of the geologic framework. In contrast, the extrapolation of hydraulic properties beyond the volume investigated with interfering aquifer tests is strongly affected by the complexity of a given framework. Testing at Pahute Mesa illustrates how this method can be employed to determine the appropriate level of geologic complexity for large-scale groundwater modeling.

  3. Testing the suitability of geologic frameworks for extrapolating hydraulic properties across regional scales

    NASA Astrophysics Data System (ADS)

    Mirus, Benjamin B.; Halford, Keith; Sweetkind, Don; Fenelon, Joe

    2016-08-01

    The suitability of geologic frameworks for extrapolating hydraulic conductivity ( K) to length scales commensurate with hydraulic data is difficult to assess. A novel method is presented for evaluating assumed relations between K and geologic interpretations for regional-scale groundwater modeling. The approach relies on simultaneous interpretation of multiple aquifer tests using alternative geologic frameworks of variable complexity, where each framework is incorporated as prior information that assumes homogeneous K within each model unit. This approach is tested at Pahute Mesa within the Nevada National Security Site (USA), where observed drawdowns from eight aquifer tests in complex, highly faulted volcanic rocks provide the necessary hydraulic constraints. The investigated volume encompasses 40 mi3 (167 km3) where drawdowns traversed major fault structures and were detected more than 2 mi (3.2 km) from pumping wells. Complexity of the five frameworks assessed ranges from an undifferentiated mass of rock with a single unit to 14 distinct geologic units. Results show that only four geologic units can be justified as hydraulically unique for this location. The approach qualitatively evaluates the consistency of hydraulic property estimates within extents of investigation and effects of geologic frameworks on extrapolation. Distributions of transmissivity are similar within the investigated extents irrespective of the geologic framework. In contrast, the extrapolation of hydraulic properties beyond the volume investigated with interfering aquifer tests is strongly affected by the complexity of a given framework. Testing at Pahute Mesa illustrates how this method can be employed to determine the appropriate level of geologic complexity for large-scale groundwater modeling.

  4. Testing the suitability of geologic frameworks for extrapolating hydraulic properties across regional scales

    DOE PAGESBeta

    Mirus, Benjamin B.; Halford, Keith J.; Sweetkind, Donald; Fenelon, Joseph M.

    2016-02-18

    The suitability of geologic frameworks for extrapolating hydraulic conductivity (K) to length scales commensurate with hydraulic data is difficult to assess. A novel method is presented for evaluating assumed relations between K and geologic interpretations for regional-scale groundwater modeling. The approach relies on simultaneous interpretation of multiple aquifer tests using alternative geologic frameworks of variable complexity, where each framework is incorporated as prior information that assumes homogeneous K within each model unit. This approach is tested at Pahute Mesa within the Nevada National Security Site (USA), where observed drawdowns from eight aquifer tests in complex, highly faulted volcanic rocks providemore » the necessary hydraulic constraints. The investigated volume encompasses 40 mi3 (167 km3) where drawdowns traversed major fault structures and were detected more than 2 mi (3.2 km) from pumping wells. Complexity of the five frameworks assessed ranges from an undifferentiated mass of rock with a single unit to 14 distinct geologic units. Results show that only four geologic units can be justified as hydraulically unique for this location. The approach qualitatively evaluates the consistency of hydraulic property estimates within extents of investigation and effects of geologic frameworks on extrapolation. Distributions of transmissivity are similar within the investigated extents irrespective of the geologic framework. In contrast, the extrapolation of hydraulic properties beyond the volume investigated with interfering aquifer tests is strongly affected by the complexity of a given framework. As a result, testing at Pahute Mesa illustrates how this method can be employed to determine the appropriate level of geologic complexity for large-scale groundwater modeling.« less

  5. The key to commercial-scale geological CO2 sequestration: Displaced fluid management

    USGS Publications Warehouse

    Surdam, R.C.; Jiao, Z.; Stauffer, P.; Miller, T.

    2011-01-01

    The Wyoming State Geological Survey has completed a thorough inventory and prioritization of all Wyoming stratigraphic units and geologic sites capable of sequestering commercial quantities of CO2 (5-15 Mt CO 2/year). This multi-year study identified the Paleozoic Tensleep/Weber Sandstone and Madison Limestone (and stratigraphic equivalent units) as the leading clastic and carbonate reservoir candidates for commercial-scale geological CO2 sequestration in Wyoming. This conclusion was based on unit thickness, overlying low permeability lithofacies, reservoir storage and continuity properties, regional distribution patterns, formation fluid chemistry characteristics, and preliminary fluid-flow modeling. This study also identified the Rock Springs Uplift in southwestern Wyoming as the most promising geological CO2 sequestration site in Wyoming and probably in any Rocky Mountain basin. The results of the WSGS CO2 geological sequestration inventory led the agency and colleagues at the UW School of Energy Resources Carbon Management Institute (CMI) to collect available geologic, petrophysical, geochemical, and geophysical data on the Rock Springs Uplift, and to build a regional 3-D geologic framework model of the Uplift. From the results of these tasks and using the FutureGen protocol, the WSGS showed that on the Rock Springs Uplift, the Weber Sandstone has sufficient pore space to sequester 18 billion tons (Gt) of CO2, and the Madison Limestone has sufficient pore space to sequester 8 Gt of CO2. ?? 2011 Published by Elsevier Ltd.

  6. Approaches to large scale unsaturated flow in heterogeneous, stratified, and fractured geologic media

    SciTech Connect

    Ababou, R.

    1991-08-01

    This report develops a broad review and assessment of quantitative modeling approaches and data requirements for large-scale subsurface flow in radioactive waste geologic repository. The data review includes discussions of controlled field experiments, existing contamination sites, and site-specific hydrogeologic conditions at Yucca Mountain. Local-scale constitutive models for the unsaturated hydrodynamic properties of geologic media are analyzed, with particular emphasis on the effect of structural characteristics of the medium. The report further reviews and analyzes large-scale hydrogeologic spatial variability from aquifer data, unsaturated soil data, and fracture network data gathered from the literature. Finally, various modeling strategies toward large-scale flow simulations are assessed, including direct high-resolution simulation, and coarse-scale simulation based on auxiliary hydrodynamic models such as single equivalent continuum and dual-porosity continuum. The roles of anisotropy, fracturing, and broad-band spatial variability are emphasized. 252 refs.

  7. Fingernail Growth and Time-Distance Rates in Geology.

    ERIC Educational Resources Information Center

    Rowland, Stephen M.

    1983-01-01

    Fingernail growth rates are easily measured over a period of a few weeks and provide opportunities for students to improve graphing skills. Fingernail growth rates are approximately the same as sea-floor spreading rates and can be used for comparing the rates of other geological processes such as tectonic uplift. (Author/JN)

  8. Review of time scales. [Universal Time-Ephemeris Time-International Atomic Time

    NASA Technical Reports Server (NTRS)

    Guinot, B.

    1974-01-01

    The basic time scales are presented: International Atomic Time, Universal Time, and Universal Time (Coordinated). These scales must be maintained in order to satisfy specific requirements. It is shown how they are obtained and made available at a very high level of precision.

  9. Kalman plus weights: a time scale algorithm

    NASA Technical Reports Server (NTRS)

    Greenhall, C. A.

    2001-01-01

    KPW is a time scale algorithm that combines Kalman filtering with the basic time scale equation (BTSE). A single Kalman filter that estimates all clocks simultaneously is used to generate the BTSE frequency estimates, while the BTSE weights are inversely proportional to the white FM variances of the clocks. Results from simulated clock ensembles are compared to previous simulation results from other algorithms.

  10. Multiple time scale methods in tokamak magnetohydrodynamics

    SciTech Connect

    Jardin, S.C.

    1984-01-01

    Several methods are discussed for integrating the magnetohydrodynamic (MHD) equations in tokamak systems on other than the fastest time scale. The dynamical grid method for simulating ideal MHD instabilities utilizes a natural nonorthogonal time-dependent coordinate transformation based on the magnetic field lines. The coordinate transformation is chosen to be free of the fast time scale motion itself, and to yield a relatively simple scalar equation for the total pressure, P = p + B/sup 2//2..mu../sub 0/, which can be integrated implicitly to average over the fast time scale oscillations. Two methods are described for the resistive time scale. The zero-mass method uses a reduced set of two-fluid transport equations obtained by expanding in the inverse magnetic Reynolds number, and in the small ratio of perpendicular to parallel mobilities and thermal conductivities. The momentum equation becomes a constraint equation that forces the pressure and magnetic fields and currents to remain in force balance equilibrium as they evolve. The large mass method artificially scales up the ion mass and viscosity, thereby reducing the severe time scale disparity between wavelike and diffusionlike phenomena, but not changing the resistive time scale behavior. Other methods addressing the intermediate time scales are discussed.

  11. Time scale in quasifission reactions

    SciTech Connect

    Back, B.B.; Paul, P.; Nestler, J.

    1995-08-01

    The quasifission process arises from the hindrance of the complete fusion process when heavy-ion beams are used. The strong dissipation in the system tends to prevent fusion and lead the system towards reseparation into two final products of similar mass reminiscent of a fission process. This dissipation slows down the mass transfer and shape transformation and allows for the emission of high energy {gamma}-rays during the process, albeit with a low probability. Giant Dipole {gamma} rays emitted during this time have a characteristic spectral shape and may thus be discerned in the presence of a background of {gamma} rays emitted from the final fission-like fragments. Since the rate of GDR {gamma} emission is very well established, the strength of this component may therefore be used to measure the timescale of the quasifission process. In this experiment we studied the reaction between 368-MeV {sup 58}Ni and a {sup 165}Ho target, where deep inelastic scattering and quasifission processes are dominant. Coincidences between fission fragments (detected in four position-sensitive avalanche detectors) and high energy {gamma} rays (measured in a 10{close_quotes} x 10{close_quotes} actively shielded NaI detector) were registered. Beams were provided by the Stony Brook Superconducting Linac. The {gamma}-ray spectrum associated with deep inelastic scattering events is well reproduced by statistical cooling of projectile and target-like fragments with close to equal initial excitation energy sharing. The y spectrum associated with quasifission events is well described by statistical emission from the fission fragments alone, with only weak evidence for GDR emission from the mono-nucleus. A 1{sigma} limit of t{sub ss} < 11 x 10{sup -21} s is obtained for the mono-nucleus lifetime, which is consistent with the lifetime obtained from quasifission fragment angular distributions. A manuscript was accepted for publication.

  12. Heterogeneity and Scaling in Geologic Media: Applications to Transport in the Vadose and Saturated Zones

    SciTech Connect

    Brown, Stephen R.

    2003-06-01

    Heterogeneity and Scaling in Geologic Media: Applications to Transport in the Vadose and Saturated Zones Stephen Brown, Gregory Boitnott, and Martin Smith New England Research In rocks and soils, the bulk geophysical and transport properties of the matrix and of fracture systems are determined by the juxtaposition of geometric features at many length scales. For sedimentary materials the length scales are: the pore scale (irregularities in grain surface roughness and cementation), the scale of grain packing faults (and the resulting correlated porosity structures), the scale dominated by sorting or winnowing due to depositional processes, and the scale of geomorphology at the time of deposition. We are studying the heterogeneity and anisotropy in geometry, permeability, and geophysical response from the pore (microscopic), laboratory (mesoscopic), and backyard field (macroscopic) scales. In turn these data are being described and synthesized for development of mathematical models. Eventually, we will perform parameter studies to explore these models in the context of transport in the vadose and saturated zones. We have developed a multi-probe physical properties scanner which allows for the mapping of geophysical properties on a slabbed sample or core. This device allows for detailed study of heterogeneity at those length scales most difficult to quantify using standard field and laboratory practices. The measurement head consists of a variety of probes designed to make local measurements of various properties, including: gas permeability, acoustic velocities (compressional and shear), complex electrical impedance (4 electrode, wide frequency coverage), and ultrasonic reflection (ultrasonic impedance and permeability). We can thus routinely generate detailed geophysical maps of a particular sample. With the exception of the acoustic velocity, we are testing and modifying these probes as necessary for use on soil samples. As a baseline study we have been

  13. Time-dependent corona models - Scaling laws

    NASA Technical Reports Server (NTRS)

    Korevaar, P.; Martens, P. C. H.

    1989-01-01

    Scaling laws are derived for the one-dimensional time-dependent Euler equations that describe the evolution of a spherically symmetric stellar atmosphere. With these scaling laws the results of the time-dependent calculations by Korevaar (1989) obtained for one star are applicable over the whole Hertzsprung-Russell diagram and even to elliptic galaxies. The scaling is exact for stars with the same M/R-ratio and a good approximation for stars with a different M/R-ratio. The global relaxation oscillation found by Korevaar (1989) is scaled to main sequence stars, a solar coronal hole, cool giants and elliptic galaxies.

  14. Non-parametric causal assessment in deep-time geological records

    NASA Astrophysics Data System (ADS)

    Agasøster Haaga, Kristian; Diego, David; Brendryen, Jo; Hannisdal, Bjarte

    2016-04-01

    The interplay between climate variables and the timing of their feedback mechanisms are typically investigated using fully coupled climate system models. However, as we delve deeper into the geological past, mechanistic process models become increasingly uncertain, making nonparametric approaches more attractive. Here we explore the use of two conceptually different methods for nonparametric causal assessment in palaeoenvironmental archives of the deep past: convergent cross mapping (CCM) and information transfer (IT). These methods have the potential to capture interactions in complex systems even when data are sparse and noisy, which typically characterises geological proxy records. We apply these methods to proxy time series that capture interlinked components of the Earth system at different temporal scales, and quantify both the interaction strengths and the feedback lags between the variables. Our examples include the linkage between the ecological prominence of common planktonic species to oceanographic changes over the last ~65 million years, and global interactions and teleconnections within the climate system during the last ~800,000 years.

  15. Correlations in fossil extinction and origination rates through geological time.

    PubMed

    Kirchner, J W; Weil, A

    2000-07-01

    Recent analyses have suggested that extinction and origination rates exhibit long-range correlations, implying that the fossil record may be controlled by self-organized criticality or other scale-free internal dynamics of the biosphere. Here we directly test for correlations in the fossil record by calculating the autocorrelation of extinction [corrected] and origination rates through time. Our results show that extinction rates are uncorrelated beyond the average duration of a stratigraphic interval. Thus, they lack the long-range correlations predicted by the self-organized criticality hypothesis. In contrast, origination rates show strong autocorrelations due to long-term trends. After detrending, origination rates generally show weak positive correlations at lags of 5-10 million years (Myr) and weak negative correlations at lags of 10-30 Myr, consistent with aperiodic oscillations around their long-term trends. We hypothesize that origination rates are more correlated than extinction rates because originations of new taxa create new ecological niches and new evolutionary pathways for reaching them, thus creating conditions that favour further diversification. PMID:10972124

  16. Correlations in fossil extinction and origination rates through geological time.

    PubMed Central

    Kirchner, J W; Weil, A

    2000-01-01

    Recent analyses have suggested that extinction and origination rates exhibit long-range correlations, implying that the fossil record may be controlled by self-organized criticality or other scale-free internal dynamics of the biosphere. Here we directly test for correlations in the fossil record by calculating the autocorrelation of extinction [corrected] and origination rates through time. Our results show that extinction rates are uncorrelated beyond the average duration of a stratigraphic interval. Thus, they lack the long-range correlations predicted by the self-organized criticality hypothesis. In contrast, origination rates show strong autocorrelations due to long-term trends. After detrending, origination rates generally show weak positive correlations at lags of 5-10 million years (Myr) and weak negative correlations at lags of 10-30 Myr, consistent with aperiodic oscillations around their long-term trends. We hypothesize that origination rates are more correlated than extinction rates because originations of new taxa create new ecological niches and new evolutionary pathways for reaching them, thus creating conditions that favour further diversification. PMID:10972124

  17. Modeling orbital changes on tectonic time scales

    NASA Technical Reports Server (NTRS)

    Crowley, Thomas J.

    1992-01-01

    Geologic time series indicate significant 100 ka and 400 ka pre-Pleistocene climate fluctuations, prior to the time of such fluctuations in Pleistocene ice sheets. The origin of these fluctuations must therefore depend on phenomena other than the ice sheets. In a previous set of experiments, we tested the sensitivity of an energy balance model to orbital insolation forcing, specifically focusing on the filtering effect of the Earth's geography. We found that in equatorial areas, the twice-yearly passage of the sun across the equator interacts with the precession index to generate 100 ka and 400 ka power in our modeled time series. The effect is proportional to the magnitude of land in equatorial regions. We suggest that such changes may reflect monsoonal variations in the real climate system, and the subsequent wind and weathering changes may transfer some of this signal to the marine record. A comparison with observed fluctuations of Triassic lake levels is quite favorable. A number of problems remain to be studied or clarified: (1) the EBM experiments need to be followed up by a limited number of GCM experiments; (2) the sensitivity to secular changes in orbital forcing needs to be examined; (3) the possible modifying role of sedimentary processes on geologic time series warrants considerably more study; (4) the effect of tectonic changes on Earth's rotation rate needs to be studied; and (5) astronomers need to make explicit which of their predictions are robust and geologists and astronomers have to agree on which of the predictions are most testable in the geologic record.

  18. Building 3D geological knowledge through regional scale gravity modelling for the Bowen Basin

    NASA Astrophysics Data System (ADS)

    Danis, Cara; O'Neill, Craig; Lackie, Mark

    2012-01-01

    Regional scale gravity modelling is an effective and fast way to gain geological understanding of large scale structures like the Bowen Basin. Detailed deep 3D geological knowledge has become an important component of many types of exploration and resource modelling. Current interest in the Bowen Basin for geothermal exploration highlights the need for a complete basin scale model which is compatible with thermal modelling software. The structure of the Bowen Basin is characteristic of a typical asymmetrical extensional rift basin, with up to 5km of sediment overlying the basement. By combining gravity modelling, calibrated by boreholes and seismic reflection profiles, we produce geologically reasonable 3D surfaces and structures to create a model of the Bowen Basin. This model is the final part in the completion of the 3D Sydney-Gunnedah-Bowen Basin system geological model and provides both an important framework from which detailed thermal models can be derived and a platform from which to expand with new information.

  19. Mouse Activity across Time Scales: Fractal Scenarios

    PubMed Central

    Lima, G. Z. dos Santos; Lobão-Soares, B.; do Nascimento, G. C.; França, Arthur S. C.; Muratori, L.; Ribeiro, S.; Corso, G.

    2014-01-01

    In this work we devise a classification of mouse activity patterns based on accelerometer data using Detrended Fluctuation Analysis. We use two characteristic mouse behavioural states as benchmarks in this study: waking in free activity and slow-wave sleep (SWS). In both situations we find roughly the same pattern: for short time intervals we observe high correlation in activity - a typical 1/f complex pattern - while for large time intervals there is anti-correlation. High correlation of short intervals ( to : waking state and to : SWS) is related to highly coordinated muscle activity. In the waking state we associate high correlation both to muscle activity and to mouse stereotyped movements (grooming, waking, etc.). On the other side, the observed anti-correlation over large time scales ( to : waking state and to : SWS) during SWS appears related to a feedback autonomic response. The transition from correlated regime at short scales to an anti-correlated regime at large scales during SWS is given by the respiratory cycle interval, while during the waking state this transition occurs at the time scale corresponding to the duration of the stereotyped mouse movements. Furthermore, we find that the waking state is characterized by longer time scales than SWS and by a softer transition from correlation to anti-correlation. Moreover, this soft transition in the waking state encompass a behavioural time scale window that gives rise to a multifractal pattern. We believe that the observed multifractality in mouse activity is formed by the integration of several stereotyped movements each one with a characteristic time correlation. Finally, we compare scaling properties of body acceleration fluctuation time series during sleep and wake periods for healthy mice. Interestingly, differences between sleep and wake in the scaling exponents are comparable to previous works regarding human heartbeat. Complementarily, the nature of these sleep-wake dynamics could lead to a better

  20. Geologic Noise in Near--Surface Time--Domain Electromagnetic Induction Data

    NASA Astrophysics Data System (ADS)

    Weiss, C. J.; Everett, M. E.

    2001-12-01

    Controlled--source electromagnetic induction is a geophysical technique commonly used to aid in the identification of both anthropogenic and naturally occuring features, such as unexploded ordnance or high--permeability fluid pathways, in Earth's shallow subsurface. However, electromagnetic responses are oftentimes difficult to interpret owing to the complex, multiscale heterogeneous nature of the underlying electrical conductivity structure. We show evidence here which indicates that electromagnetic responses are indeed fractal signals, reflecting a very rough distribution of electrical conductivity in the underlying Earth. Time--domain electromagnetic data collected across a section of colluvial fill in the Rio Grande Rift valley near Albuquerque, New Mexico, show that the fractal properties of the surface electromagnetic responses depend on the complexity of the causative geological structure. Similar experiments in the frequency domain suggest that the small--scale fluctuations in the electromagnetic response due to geological noise are inherently reproducible, and are not caused by random instrumental or atmospheric effects as often assumed. New approaches to modeling electromagnetic responses are required in order to take full advantage of the rich information content of near--surface electromagnetic data. This work was supported in part by the United States Department of Energy under Contract DE--AC04--94AL85000. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy.

  1. Time Scale Optimization and the Hunt for Astronomical Cycles in Deep Time Strata

    NASA Astrophysics Data System (ADS)

    Meyers, Stephen R.

    2016-04-01

    A valuable attribute of astrochronology is the direct link between chronometer and climate change, providing a remarkable opportunity to constrain the evolution of the surficial Earth System. Consequently, the hunt for astronomical cycles in strata has spurred the development of a rich conceptual framework for climatic/oceanographic change, and has allowed exploration of the geologic record with unprecedented temporal resolution. Accompanying these successes, however, has been a persistent skepticism about appropriate astrochronologic testing and circular reasoning: how does one reliably test for astronomical cycles in stratigraphic data, especially when time is poorly constrained? From this perspective, it would seem that the merits and promise of astrochronology (e.g., a geologic time scale measured in ≤400 kyr increments) also serves as its Achilles heel, if the confirmation of such short rhythms defies rigorous statistical testing. To address these statistical challenges in astrochronologic testing, a new approach has been developed that (1) explicitly evaluates time scale uncertainty, (2) is resilient to common problems associated with spectrum confidence level assessment and 'multiple testing', and (3) achieves high statistical power under a wide range of conditions (it can identify astronomical cycles when present in data). Designated TimeOpt (for "time scale optimization"; Meyers 2015), the method employs a probabilistic linear regression model framework to investigate amplitude modulation and frequency ratios (bundling) in stratigraphic data, while simultaneously determining the optimal time scale. This presentation will review the TimeOpt method, and demonstrate how the flexible statistical framework can be further extended to evaluate (and optimize upon) complex sedimentation rate models, enhancing the statistical power of the approach, and addressing the challenge of unsteady sedimentation. Meyers, S. R. (2015), The evaluation of eccentricity

  2. Time scale construction from multiple sources of information (Invited)

    NASA Astrophysics Data System (ADS)

    Malinverno, A.

    2013-12-01

    Geological age estimates are provided by diverse chronometers, such as radiometric measurements, astrochronology, and the spacing of magnetic anomalies recorded on mid-ocean ridges by seafloor spreading. These age estimates are affected by errors that can be systematic (e.g., biased radiometric dates due to imperfect assumptions) or random (e.g., imprecise recording of astronomical cycles in sedimentary records). Whereas systematic errors can be reduced by improvements in technique and calibration, uncertainties due to random errors will always be present and need to be dealt with. A Bayesian framework can be used to construct an integrated time scale that is based on several uncertain sources of information. In this framework, each piece of data and the final time scale have an associated probability distribution that describes their uncertainty. The key calculation is to determine the uncertainty in the time scale from the uncertain data that constrain it. In practice, this calculation can be performed by Monte Carlo sampling. In Markov chain Monte Carlo algorithms, the time scale is iteratively perturbed and the perturbed time scale is accepted or rejected depending on how closely it fits the data. The final result is a large ensemble of possible time scales that are consistent with all the uncertain data; while the average of this ensemble defines a 'best' time scale, the ensemble variability quantifies the time scale uncertainty. An example of this approach is the M-sequence (Late Jurassic-Early Cretaceous, ~160-120 Ma) MHTC12 geomagnetic polarity time scale (GPTS) of Malinverno et al. (2012, J. Geophys. Res., B06104, doi:10.1029/2012JB009260). Previous GPTSs were constructed by interpolating between dated marine magnetic anomalies while assuming constant or smoothly varying spreading rates. These GPTSs were typically based on magnetic lineations from one or a few selected spreading centers, and an undesirable result is that they imply larger spreading rate

  3. Evaluating Experience-Based Geologic Field Instruction: Lessons Learned from A Large-Scale Eye-Tracking Experiment

    NASA Astrophysics Data System (ADS)

    Tarduno, J. A.; Walders, K.; Bono, R. K.; Pelz, J.; Jacobs, R.

    2015-12-01

    A course centered on experience-based learning in field geology has been offered ten times at the University of Rochester. The centerpiece of the course is a 10-day field excursion to California featuring a broad cross-section of the geology of the state, from the San Andreas Fault to Death Valley. Here we describe results from a large-scale eye-tracking experiment aimed at understanding how experts and novices acquire visual geologic information. One ultimate goal of the project is to determine whether expert gaze patterns can be quantified to improve the instruction of beginning geology students. Another goal is to determine if aspects of the field experience can be transferred to the classroom/laboratory. Accordingly, ultra-high resolution segmented panoramic images have been collected at key sites visited during the field excursion. We have found that strict controls are needed in the field to obtain meaningful data; this often involves behavior atypical of geologists (e.g. limiting the field of view prior to data collection and placing time limits on scene viewing). Nevertheless some general conclusions can be made from a select data set. After an initial quick search, experts tend to exhibit scanning behavior that appears to support hypothesis testing. Novice fixations appear to define a scattered search pattern and/or one distracted by geologic noise in a scene. Noise sources include modern erosion features and vegetation. One way to quantify noise is through the use of saliency maps. With the caveat that our expert data set is small, our preliminary analysis suggests that experts tend to exhibit top-down behavior (indicating hypothesis driven responses) whereas novices show bottom-up gaze patterns, influenced by more salient features in a scene. We will present examples and discuss how these observations might be used to improve instruction.

  4. How Old? Tested and Trouble-Free Ways to Convey Geologic Time

    ERIC Educational Resources Information Center

    Clary, Renee

    2009-01-01

    Geologic time, or the time frame of our planet's history, is several orders of magnitude greater than general human understanding of "time." When students hear that our planet has a 4.6-billion-year history, they do not necessarily comprehend the magnitude of deep time, the huge expanse of time that has passed from the origin of Earth through the…

  5. Geological dates and molecular rates: fish DNA sheds light on time dependency.

    PubMed

    Burridge, Christopher P; Craw, Dave; Fletcher, David; Waters, Jonathan M

    2008-04-01

    Knowledge of DNA evolution is central to our understanding of biological history, but how fast does DNA change? Previously, pedigree and ancient DNA studies--focusing on evolution in the short term--have yielded molecular rate estimates substantially faster than those based on deeper phylogenies. It has recently been suggested that short-term, elevated molecular rates decay exponentially over 1-2 Myr to long-term, phylogenetic rates, termed "time dependency of molecular rates." This transition has potential to confound molecular inferences of demographic parameters and dating of many important evolutionary events. Here, we employ a novel approach--geologically dated changes in river drainages and isolation of fish populations--to document rates of mitochondrial DNA change over a range of temporal scales. This method utilizes precise spatiotemporal disruptions of linear freshwater systems and hence avoids many of the limitations associated with typical DNA calibration methods involving fossil data or island formation. Studies of freshwater-limited fishes across the South Island of New Zealand have revealed that genetic relationships reflect past, rather than present, drainage connections. Here, we use this link between drainage geology and genetics to calibrate rates of molecular evolution across nine events ranging in age from 0.007 Myr (Holocene) to 5.0 Myr (Pliocene). Molecular rates of change in galaxiid fishes from calibration points younger than 200 kyr were faster than those based on older calibration points. This study provides conclusive evidence of time dependency in molecular rates as it is based on a robust calibration system that was applied to closely related taxa, and analyzed using a consistent and rigorous methodology. The time dependency observed here appears short-lived relative to previous suggestions (1-2 Myr), which has bearing on the accuracy of molecular inferences drawn from processes operating within the Quaternary and mechanisms invoked to

  6. Observing Reality on Different Time Scales

    NASA Astrophysics Data System (ADS)

    Alyushin, Alexey

    2005-10-01

    In the first part of the paper, I examine cases of acceleration of perception and cognition and provide my explanation of the mechanism of the effect. The explanation rests on the conception of neuronal temporal frames, or windows of simultaneity. Frames have different standard durations and yield to stretching and compressing. I suggest it to be the cause of the effect, as well as the ground for differences in perceptive time scales of living beings. In the second part, I apply the conception of temporal frames to model observation in the extended time scales that reach far beyond the temporal perceptive niche of individual living beings. Duration of a frame is taken as the basic parameter setting a particular time scale. By substituting a different frame duration, we set a hypothetical time scale and emulate observing reality in a wider or a narrower angle of embracing events in time. I discuss the status of observer in its relation to objective reality, and examine how reality does change its appearance when observed in different time scales.

  7. Time scales involved in emergent market coherence

    NASA Astrophysics Data System (ADS)

    Kwapień, J.; Drożdż, S.; Speth, J.

    2004-06-01

    In addressing the question of the time scales characteristic for the market formation, we analyze high-frequency tick-by-tick data from the NYSE and from the German market. By using returns on various time scales ranging from seconds or minutes up to 2 days, we compare magnitude of the largest eigenvalue of the correlation matrix for the same set of securities but for different time scales. For various sets of stocks of different capitalization (and the average trading frequency), we observe a significant elevation of the largest eigenvalue with increasing time scale. Our results from the correlation matrix study can be considered as a manifestation of the so-called Epps effect. There is no unique explanation of this effect and it seems that many different factors play a role here. One of such factors is randomness in transaction moments for different stocks. Another interesting conclusion to be drawn from our results is that in the contemporary markets the emergence of significant correlations occurs on time scales much smaller than in the more distant history.

  8. The Laplace transform on time scales revisited

    NASA Astrophysics Data System (ADS)

    Davis, John M.; Gravagne, Ian A.; Jackson, Billy J.; Marks, Robert J., II; Ramos, Alice A.

    2007-08-01

    In this work, we reexamine the time scale Laplace transform as defined by Bohner and Peterson [M. Bohner, A. Peterson, Dynamic Equations on Time Scales: An Introduction with Applications, Birkhauser, Boston, 2001; M. Bohner, A. Peterson, Laplace transform and Z-transform: Unification and extension, Methods Appl. Anal. 9 (1) (2002) 155-162]. In particular, we give conditions on the class of functions which have a transform, develop an inversion formula for the transform, and further, we provide a convolution for the transform. The notion of convolution leads to considering its algebraic structure--in particular the existence of an identity element--motivating the development of the Dirac delta functional on time scales. Applications and examples of these concepts are given.

  9. Global scale precipitation from monthly to centennial scales: empirical space-time scaling analysis, anthropogenic effects

    NASA Astrophysics Data System (ADS)

    de Lima, Isabel; Lovejoy, Shaun

    2016-04-01

    The characterization of precipitation scaling regimes represents a key contribution to the improved understanding of space-time precipitation variability, which is the focus here. We conduct space-time scaling analyses of spectra and Haar fluctuations in precipitation, using three global scale precipitation products (one instrument based, one reanalysis based, one satellite and gauge based), from monthly to centennial scales and planetary down to several hundred kilometers in spatial scale. Results show the presence - similarly to other atmospheric fields - of an intermediate "macroweather" regime between the familiar weather and climate regimes: we characterize systematically the macroweather precipitation temporal and spatial, and joint space-time statistics and variability, and the outer scale limit of temporal scaling. These regimes qualitatively and quantitatively alternate in the way fluctuations vary with scale. In the macroweather regime, the fluctuations diminish with time scale (this is important for seasonal, annual, and decadal forecasts) while anthropogenic effects increase with time scale. Our approach determines the time scale at which the anthropogenic signal can be detected above the natural variability noise: the critical scale is about 20 - 40 yrs (depending on the product, on the spatial scale). This explains for example why studies that use data covering only a few decades do not easily give evidence of anthropogenic changes in precipitation, as a consequence of warming: the period is too short. Overall, while showing that precipitation can be modeled with space-time scaling processes, our results clarify the different precipitation scaling regimes and further allow us to quantify the agreement (and lack of agreement) of the precipitation products as a function of space and time scales. Moreover, this work contributes to clarify a basic problem in hydro-climatology, which is to measure precipitation trends at decadal and longer scales and to

  10. Analysis of the time scales in time periodic Darcy flows

    NASA Astrophysics Data System (ADS)

    Zhu, T.; Waluga, C.; Wohlmuth, B.; Manhart, M.

    2014-12-01

    We investigate unsteady flow in a porous medium under time - periodic (sinusoidal) pressure gradient. DNS were performed to benchmark the analytical solution of the unsteady Darcy equation with two different expressions of the time scale : one given by a consistent volume averaging of the Navier - Stokes equation [1] with a steady state closure for the flow resistance term, another given by volume averaging of the kinetic energy equation [2] with a closure for the dissipation rate . For small and medium frequencies, the analytical solutions with the time scale obtained by the energy approach compare well with the DNS results in terms of amplitude and phase lag. For large frequencies (f > 100 [Hz]) we observe a slightly smaller damping of the amplitude. This study supports the use of the unsteady form of Darcy's equation with constant coefficients to solve time - periodic Darcy flows at low and medium frequencies. Our DNS simulations, however, indicate that the time scale predicted by the VANS approach together with a steady - state closure for the flow resistance term is too small. The one obtained by the energy approach matches the DNS results well. At large frequencies, the amplitudes deviate slightly from the analytical solution of the unsteady Darcy equation. Note that at those high frequencies, the flow amplitudes remain below 1% of those of steady state flow. This result indicates that unsteady porous media flow can approximately be described by the unsteady Darcy equation with constant coefficients for a large range of frequencies, provided, the proper time scale has been found.

  11. U.S. Geological Survey Near Real-Time Dst Index

    USGS Publications Warehouse

    Gannon, J.L.; Love, J.J.; Friberg, P.A.; Stewart, D.C.; Lisowski, S.W.

    2011-01-01

    The operational version of the United States Geological Survey one-minute Dst index (a global geomagnetic disturbance-intensity index for scientific studies and definition of space-weather effects) uses either four- or three-station input (including Honolulu, Hawaii; San Juan, Puerto Rico; Hermanus, South Africa; and Kakioka, Japan; or Honolulu, San Juan and Guam) and a method based on the U.S. Geological Survey definitive Dst index, in which Dst is more rigorously calculated. The method uses a combination of time-domain techniques and frequency-space filtering to produce the disturbance time series at an individual observatory. The operational output is compared to the U.S. Geological Survey one-minute Dst index (definitive version) and to the Kyoto (Japan) Final Dst to show that the U.S. Geological Survey operational output matches both definitive indices well.

  12. Geologic hazard monitoring with real-time GPS (Invited)

    NASA Astrophysics Data System (ADS)

    Lisowski, M.; Langbein, J. O.; Murray-Moraleda, J. R.; Poland, M. P.; Hudnut, K. W.; Cervelli, P. F.; King, N. E.

    2009-12-01

    The USGS Earthquake and Volcano Hazards Science Centers are developing a high-rate (1-s epoch), real-time ground deformation monitoring system using data streamed from continuously recording GPS stations. We began by evaluating the ability of GPS data reduction software to recover offsets in a displacement test data set generated by offsetting a GPS antenna by measured amounts. We found that offsets as large as several meters and as small as 1 cm could be reliably resolved. Our methods and initial results were summarized in USGS Open File Report 1235 (http://pubs.usgs.gov/of/2006/1235/of2006-1235.pdf). Further evaluation of GPS software using raw data from the report and real-time GPS data were conducted after publication of the report. Based upon these results, we selected software that could produce both double difference (baseline) and single difference (point positioning) solutions. Using this software, we are now running real-time, 1-s, fixed-ambiguity, double-difference solutions for USGS deformation monitoring networks in Southern California, the San Francisco Bay Area, Long Valley, and at several Cascades volcanoes. GPS data are streamed over the Internet to processing centers in Pasadena, CA, and Vancouver, WA. Solutions are generally reliable, but we note solution gaps caused by the breakdown in the GPS data streams and intervals when baseline ambiguities are not resolved in some of the longer (>50 km) baselines. We have not yet attempted real-time point-position solutions because we lack accurate real-time satellite clock corrections. We plan to implement this technique in the future by either calculating satellite clock corrections using a network of stations or by applying corrections produced by JPL. We currently generate alarms for data gaps in the real-time GPS solutions and plan to automate displacement anomaly detection using an algorithm that removes common-mode and multi-path noise.

  13. Structure of Student Time Management Scale (STMS)

    ERIC Educational Resources Information Center

    Balamurugan, M.

    2013-01-01

    With the aim of constructing a Student Time Management Scale (STMS), the initial version was administered and data were collected from 523 standard eleventh students. (Mean age = 15.64). The data obtained were subjected to Reliability and Factor analysis using PASW Statistical software version 18. From 42 items 14 were dropped, resulting in the…

  14. Digital Renovation of the Atlas of Mars 1:15,000,000-Scale Global Geologic Series Maps

    NASA Astrophysics Data System (ADS)

    Skinner, J. A., Jr.; Hare, T. M.; Tanaka, K. L.

    2006-03-01

    We have manually re-digitized the Viking-based 1:15M scale geologic maps using MDIM 2.1 and MOLA shaded-relief images as base images. These efforts have produced fully-registered geologic maps with structure and associated metadata.

  15. Use of geology in the interpretation of core-scale relative permeability data

    SciTech Connect

    Ringrose, P.S.; Jensen, J.L.; Sorbie, K.S.

    1996-09-01

    A number of factors, such as wettability, pore-size distribution, and core-scale heterogeneity, are known to affect the measured relative permeability in core plug samples. This paper focuses on the influence of geological structure at the laminaset scale on water-oil imbibition relative permeability curves. The endpoint positions and curve shapes vary as a function of the type of internal heterogeneity, the flow rate, and the assumptions on the pore-scale petrophysics (e.g. wettability). Interaction between the capillary forces and heterogeneity can occur at the cm-dm scale, which results in widely varying two-phase flow behavior for rocks with the same single-phase permeability. The geometry of heterogeneity as expressed in standard geological descriptions (e.g., cross-laminated, ripple-laminated, plane-laminated) can be translated into features of the expected relative permeability behavior for each rock type, thus aiding the interpretation of relative permeability data. The authors illustrate how their findings can help to interpret sets of relative permeability data from the field, using some examples from the Admire sand, El Dorado Field, Kansas.

  16. Pore scale modeling of reactive transport involved in geologic CO2 sequestration

    SciTech Connect

    Kang, Qinjin; Lichtner, Peter C; Viswanathan, Hari S; Abdel-fattah, Amr I

    2009-01-01

    We apply a multi-component reactive transport lattice Boltzmann model developed in previolls studies to modeling the injection of a C02 saturated brine into various porous media structures at temperature T=25 and 80 C. The porous media are originally consisted of calcite. A chemical system consisting of Na+, Ca2+, Mg2+, H+, CO2(aq), and CI-is considered. The fluid flow, advection and diHusion of aqueous species, homogeneous reactions occurring in the bulk fluid, as weB as the dissolution of calcite and precipitation of dolomite are simulated at the pore scale. The effects of porous media structure on reactive transport are investigated. The results are compared with continuum scale modeling and the agreement and discrepancy are discussed. This work may shed some light on the fundamental physics occurring at the pore scale for reactive transport involved in geologic C02 sequestration.

  17. Accuracy metrics for judging time scale algorithms

    NASA Technical Reports Server (NTRS)

    Douglas, R. J.; Boulanger, J.-S.; Jacques, C.

    1994-01-01

    Time scales have been constructed in different ways to meet the many demands placed upon them for time accuracy, frequency accuracy, long-term stability, and robustness. Usually, no single time scale is optimum for all purposes. In the context of the impending availability of high-accuracy intermittently-operated cesium fountains, we reconsider the question of evaluating the accuracy of time scales which use an algorithm to span interruptions of the primary standard. We consider a broad class of calibration algorithms that can be evaluated and compared quantitatively for their accuracy in the presence of frequency drift and a full noise model (a mixture of white PM, flicker PM, white FM, flicker FM, and random walk FM noise). We present the analytic techniques for computing the standard uncertainty for the full noise model and this class of calibration algorithms. The simplest algorithm is evaluated to find the average-frequency uncertainty arising from the noise of the cesium fountain's local oscillator and from the noise of a hydrogen maser transfer-standard. This algorithm and known noise sources are shown to permit interlaboratory frequency transfer with a standard uncertainty of less than 10(exp -15) for periods of 30-100 days.

  18. Using the Geoscience Concept Inventory to Understand how Students Learn about Geologic Time

    NASA Astrophysics Data System (ADS)

    Teed, R. E.

    2009-12-01

    108 pre-service teachers completed a standardized multiple-choice test at the beginning and at the end of a ten-week introductory survey course on geology. Four of the fifteen questions dealt explicitly with geologic time. Correct student answers that the age of the Earth is known from uranium-series dating increased significantly, but only from ~0% to about 20%. However, answers that included U-series dating with other (irrelevant) sources of evidence increased from ~10% to ~70%. On the pre-test, students avoided the U-series dating in favor of incorrect, but probably more familiar, dating techniques or combinations of dating techniques. They seem to have gained familiarity with, if not an understanding of U-series dating in the class. There was no real change in students’ conceptions of what the newly-formed Earth would have looked like. Most (70% on pre-test, 65% on post-test) chose an image that looked like the modern Earth with a single continent (which they may have believed to be Pangea). Interestingly, 78% of those who chose that image on the pre-test chose it on the post-test, so they were not guessing. This is a powerful misconception and remained intact in most cases despite the work the students did in the geology class. On the other hand, most students appeared to be guessing when they answered how long Pangea took to break up. There were no significant changes in the totals for any response, but about half students changed their answers between the pre- and post-test with no significant pattern in the changes. Responses to a choice of timelines which all included the formation of the Earth, the appearances of life, dinosaurs, and humans, and the disappearance of dinosaurs, were more complex. There was an increase in the number of students who chose the correct timeline (from 20% to 42%), and a decrease in the number who chose a timeline in which all life appears at once (from 14% to 10%). In this case some misconceptions (based on incorrect answers

  19. Robust estimates of extinction time in the geological record

    NASA Astrophysics Data System (ADS)

    Bradshaw, C. J. A.; Cooper, A.; Turney, C. S. M.; Brook, B. W.

    2012-02-01

    The rate at which a once-abundant population declines in density prior to local or global extinction can strongly influence the precision of statistical estimates of extinction time. Here we report the development of a new, robust method of inference which accounts for these potential biases and uncertainties, and test it against known simulated data and dated Pleistocene fossil remains (mammoths, horses and Neanderthals). Our method is a Gaussian-resampled, inverse-weighted McInerny et al. (GRIWM) approach which weights observations inversely according to their temporal distance from the last observation of a species' confirmed occurrence, and for dates with associated radiometric errors, is able to sample individual dates from an underlying fossilization probability distribution. We show that this leads to less biased estimates of the 'true' extinction date. In general, our method provides a flexible tool for hypothesis testing, including inferring the probability that the extinctions of pairs or groups of species overlap, and for more robustly evaluating the relative likelihood of different extinction drivers such as climate perturbation and human exploitation.

  20. Soil Hydrology Across Space And Time Scales

    NASA Astrophysics Data System (ADS)

    Mohanty, B.; Gaur, N.

    2015-12-01

    Soil moisture and hydrologic fluxes at the land surface are critical to climate feedback, hydrology, and biogeochemical cycling. Soil moisture temporal and spatial variability over catchment areas affects surface and subsurface runoff, modulates evaporation and transpiration, determines the extent of groundwater recharge and contaminant transport, and initiates or sustains feedback between the land surface and the atmosphere. At a particular point in time soil moisture content is influenced by: (1) the precipitation history, (2) the texture of the soil, which determines the water-holding capacity, (3) the slope of the land surface, which affects runoff and infiltration, and (4) the vegetation and land cover, which influences evapotranspiration and deep percolation. In other terms the partitioning of soil moisture to recharge to the groundwater, evapotranspiration to the atmosphere, and surface/subsurface runoff to the streams at different spatio-temporal scales and under different hydro-climatic conditions pose one of the greatest challenges to weather and climate prediction, water resources availability, sustainability, quality, and variability in agricultural, range and forested watersheds and hydro-climatic conditions. In this context we hypothesize that: 1) soil moisture variability is dominated by soil properties at the field scale, topographic features at the catchment/watershed scale, and vegetation characteristics and precipitation patterns at the regional scale and beyond; and 2) ensemble hydrologic fluxes (evapotranspiration, infiltration, and shallow ground water recharge) across the vadose zone at the corresponding scale can be effectively represented by one or more soil, topography, vegetation, or climate scale factors. Using ground-based and various active and passive microwave remote sensing measurements during the NASA field campaigns in the past decade we test these hypotheses. Various scaling techniques for soil moisture and soil hydrologic and

  1. A comment on the use of flushing time, residence time, and age as transport time scales

    USGS Publications Warehouse

    Monsen, N.E.; Cloern, J.E.; Lucas, L.V.; Monismith, Stephen G.

    2002-01-01

    Applications of transport time scales are pervasive in biological, hydrologic, and geochemical studies yet these times scales are not consistently defined and applied with rigor in the literature. We compare three transport time scales (flushing time, age, and residence time) commonly used to measure the retention of water or scalar quantities transported with water. We identify the underlying assumptions associated with each time scale, describe procedures for computing these time scales in idealized cases, and identify pitfalls when real-world systems deviate from these idealizations. We then apply the time scale definitions to a shallow 378 ha tidal lake to illustrate how deviations between real water bodies and the idealized examples can result from: (1) non-steady flow; (2) spatial variability in bathymetry, circulation, and transport time scales; and (3) tides that introduce complexities not accounted for in the idealized cases. These examples illustrate that no single transport time scale is valid for all time periods, locations, and constituents, and no one time scale describes all transport processes. We encourage aquatic scientists to rigorously define the transport time scale when it is applied, identify the underlying assumptions in the application of that concept, and ask if those assumptions are valid in the application of that approach for computing transport time scales in real systems.

  2. Broad Perspectives on Mars Landing Site Selection: Geological Factors from Centimeter to Kilometer Scales

    NASA Technical Reports Server (NTRS)

    Jakosky, B. M.; Golombek, M. P.

    2001-01-01

    Selection of a landing site for the '03 and later Mars surface missions represents a balance between potential science results and landing site safety. Although safety has to be the prime consideration, it is the melding together of spacecraft hazard analysis with science analysis that provides the key to understanding the nature of the surface for determining both its safety for landing and its scientific potential. Our goal here is to discuss the geological factors that go into a determination of site safety, at scales from centimeters up to kilometers, and to understand the implications for the resulting scientific return that can be expected.

  3. Hemispheric Asymmetries in Substorm Recovery Time Scales

    NASA Technical Reports Server (NTRS)

    Fillingim, M. O.; Chua, D H.; Germany, G. A.; Spann, James F.

    2009-01-01

    Previous statistical observations have shown that the recovery time scales of substorms occurring in the winter and near equinox (when the nighttime auroral zone was in darkness) are roughly twice as long as the recovery time scales for substorms occurring in the summer (when the nighttime auroral region was sunlit). This suggests that auroral substorms in the northern and southern hemispheres develop asymmetrically during solstice conditions with substorms lasting longer in the winter (dark) hemisphere than in the summer (sunlit) hemisphere. Additionally, this implies that more energy is deposited by electron precipitation in the winter hemisphere than in the summer one during substorms. This result, coupled with previous observations that have shown that auroral activity is more common when the ionosphere is in darkness and is suppressed when the ionosphere is in daylight, strongly suggests that the ionospheric conductivity plays an important role governing how magnetospheric energy is transferred to the ionosphere during substorms. Therefore, the ionosphere itself may dictate how much energy it will accept from the magnetosphere during substorms rather than this being an externally imposed quantity. Here, we extend our earlier work by statistically analyzing the recovery time scales for a large number of substorms observed in the conjugate hemispheres simultaneously by two orbiting global auroral imagers: Polar UVI and IMAGE FUV. Our current results are consistent with previous observations. The recovery time scales are observed to be longer in the winter (dark) hemisphere while the auroral activity has a shorter duration in the summer (sunlit) hemisphere. This leads to an asymmetric energy input from the magnetosphere to the ionosphere with more energy being deposited in the winter hemisphere than in the summer hemisphere.

  4. Deep time framework: A preliminary study of U.K. primary teachers' conceptions of geological time and perceptions of geoscience

    NASA Astrophysics Data System (ADS)

    Trend, Roger David

    2001-02-01

    As part of a continuing research program on the understanding of geological time (deep time) across society, a total of 51 in-service teachers of 7- to 11-year-old children was studied in relation to their orientations toward geoscience phenomena in general and deep time in particular. The first purpose of the research was to identify the nature of idiosyncratic conceptions of deep time: a cognitive deep time framework of pivotal geo-events. The second was to propose a curricular Deep Time Framework that may form the basis for constructivist approaches to in-service and pre-service teacher training which places deep time center stage. Three research questions were posed, addressing: (1) perceptions of geoscience phenomena and teachers' actual encounters with these in the classroom; (2) conceptions of deep time; and (3) approaches to teaching two curriculum areas (history and geology) which involve the interpretation of material evidence to reconstruct the past. Results enable the selection of 20 geoscience phenomena to be located in relation to teachers' interests and classroom encounters, those of high interest and high encounters being proposed as pivotal areas for further attention in teacher training. Results also reveal that in-service teachers conceive events in the geological past (geo-events) as having occurred in three distinct clusters: extremely ancient; moderately ancient; and less ancient. Within each category there is a strong lack of consensus on time-of-occurrence. Results suggest that primary teachers exhibit greater imagination in their teaching of history compared with geology and that aspects of deep time and past environments are not perceived as being of any great significance in the interpretation of geological specimens.

  5. Liquidity crises on different time scales

    NASA Astrophysics Data System (ADS)

    Corradi, Francesco; Zaccaria, Andrea; Pietronero, Luciano

    2015-12-01

    We present an empirical analysis of the microstructure of financial markets and, in particular, of the static and dynamic properties of liquidity. We find that on relatively large time scales (15 min) large price fluctuations are connected to the failure of the subtle mechanism of compensation between the flows of market and limit orders: in other words, the missed revelation of the latent order book breaks the dynamical equilibrium between the flows, triggering the large price jumps. On smaller time scales (30 s), instead, the static depletion of the limit order book is an indicator of an intrinsic fragility of the system, which is related to a strongly nonlinear enhancement of the response. In order to quantify this phenomenon we introduce a measure of the liquidity imbalance present in the book and we show that it is correlated to both the sign and the magnitude of the next price movement. These findings provide a quantitative definition of the effective liquidity, which proves to be strongly dependent on the considered time scales.

  6. Multidimensional scaling of musical time estimations.

    PubMed

    Cocenas-Silva, Raquel; Bueno, José Lino Oliveira; Molin, Paul; Bigand, Emmanuel

    2011-06-01

    The aim of this study was to identify the psycho-musical factors that govern time evaluation in Western music from baroque, classic, romantic, and modern repertoires. The excerpts were previously found to represent variability in musical properties and to induce four main categories of emotions. 48 participants (musicians and nonmusicians) freely listened to 16 musical excerpts (lasting 20 sec. each) and grouped those that seemed to have the same duration. Then, participants associated each group of excerpts to one of a set of sine wave tones varying in duration from 16 to 24 sec. Multidimensional scaling analysis generated a two-dimensional solution for these time judgments. Musical excerpts with high arousal produced an overestimation of time, and affective valence had little influence on time perception. The duration was also overestimated when tempo and loudness were higher, and to a lesser extent, timbre density. In contrast, musical tension had little influence. PMID:21853763

  7. Geologic Storage at the Basin Scale: Region-Based Basin Modeling, Powder River Basin (PRB), NE Wyoming and SE Montana

    NASA Astrophysics Data System (ADS)

    Melick, J. J.; Gardner, M. H.

    2008-12-01

    Carbon capture and storage from the over 2000 power plants is estimated at 3-5 GT/yr, which requires large- scale geologic storage of greenhouse gasses in sedimentary basins. Unfortunately, determination of basin scale storage capacity is currently based on oversimplified geologic models that are difficult to validate. Simplification involves reducing the number of geologic parameters incorporated into the model, modeling with large grid cells, and treatment of subsurface reservoirs as homogeneous media. The latter problem reflects the focus of current models on fluid and/or fluid-rock interactions rather than fluid movement and migration pathways. For example, homogeneous models over emphasize fluid behavior, like the buoyancy of super-critical CO2, and hence overestimate leakage rates. Fluid mixing and fluid-rock interactions cannot be assessed with models that only investigate these reactions at a human time scale. Preliminary and conservative estimates of the total pore volume for the PRB suggest 200 GT of supercritical CO2 can be stored in this typical onshore sedimentary basin. The connected pore volume (CPV) however is not included in this estimate. Geological characterization of the CPV relates subsurface storage units to the most prolific reservoir classes (RCs). The CPV, number of well penetrations, supercritical storage area, and potential leakage pathways characterize each RC. Within each RC, a hierarchy of stratigraphic cycles is populated with stationary sedimentation regions that control rock property distributions by correlating environment of deposition (EOD) to CPV. The degree to which CPV varies between RCs depends on the geology and attendant heterogeneity retained in the fluid flow model. Region-based modeling of the PRB incorporates 28000 wells correlated across a 70,000 Km2 area, 2 km thick on average. Within this basin, five of the most productive RCs were identified from production history and placed in a fourfold stratigraphic framework

  8. Effect of geological reaction time on transformation temperature in zeolitic diagenesis

    SciTech Connect

    Sasaki, A.

    1986-01-01

    Zeolites found in the Neogene sediments in northern Japan show a vertical zonal arrangement. The zeolite zones are formed primarily by maximum temperature during burial diagenesis. The effect of geological reaction time on transformation temperature to progress in the zeolitization was studied at eight deeply drilled wells in oil-producing areas of Japan. The strata in these wells have continuously deposited under marine environments until recent time and reach geologically maximum burial depth. The geological reaction time at the upper limit of each zeolite zone was estimated from the sedimentation rate on the basis of micropaleontological datum levels and corresponds to the burial time during which the strata have subsided. The transformation temperature of zeolites was determined from the present subsurface temperature, which was obtained by the correction of bottom-hole temperature measured during a wireline log run. The transformation temperature decreases gradually with increasing geological reaction time. The transformation temperatures of silicic glass to clinoptilolite and clinoptilolite to analcime are 58 and 105/sup 0/C at 1.8 mega-annum (Ma) and 50 and 92/sup 0/C at 5 Ma. respectively. The temperature-time relation on the zeolitization in marine sediments is similar to that in thermal maturation of organic matter in sediments.

  9. Cell water dynamics on multiple time scales

    PubMed Central

    Persson, Erik; Halle, Bertil

    2008-01-01

    Water–biomolecule interactions have been extensively studied in dilute solutions, crystals, and rehydrated powders, but none of these model systems may capture the behavior of water in the highly organized intracellular milieu. Because of the experimental difficulty of selectively probing the structure and dynamics of water in intact cells, radically different views about the properties of cell water have proliferated. To resolve this long-standing controversy, we have measured the 2H spin relaxation rate in living bacteria cultured in D2O. The relaxation data, acquired in a wide magnetic field range (0.2 mT–12 T) and analyzed in a model-independent way, reveal water dynamics on a wide range of time scales. Contradicting the view that a substantial fraction of cell water is strongly perturbed, we find that ≈85% of cell water in Escherichia coli and in the extreme halophile Haloarcula marismortui has bulk-like dynamics. The remaining ≈15% of cell water interacts directly with biomolecular surfaces and is motionally retarded by a factor 15 ± 3 on average, corresponding to a rotational correlation time of 27 ps. This dynamic perturbation is three times larger than for small monomeric proteins in solution, a difference we attribute to secluded surface hydration sites in supramolecular assemblies. The relaxation data also show that a small fraction (≈0.1%) of cell water exchanges from buried hydration sites on the microsecond time scale, consistent with the current understanding of protein hydration in solutions and crystals. PMID:18436650

  10. A perspective on time: Loss frequencies, time scales, and lifetimes

    NASA Astrophysics Data System (ADS)

    Prather, Michael; Holmes, Christopher

    2013-04-01

    The need to describe the Earth system and its components with a quantity that has units of time is ubiquitous since the 1970s work of Bolin, Rodhe and Junge. These quantities are often used as metrics of the system to describe the duration or cumulative impact of an action, such as in global-warming and ozone-depletion potentials, as in the SPARC lifetime re-assessment. The quantity designated "lifetime" is often calculated inconsistently and/or misused when applied to the subsequent evaluations of impacts. A careful set of definitions and derivations is needed to ensure that we are reporting, publishing, and comparing the same quantities. There are many different ways to derive metrics of time, and they describe different properties of the system. Here we carefully define several of those metrics - denoted here as loss frequency, time scale, and lifetime - and demonstrate which properties of the system they describe. Three generalizable examples demonstrate (i) how the non-linear chemistry of tropospheric ozone makes simple approaches for tracking pollution in error; (ii) why the lifetime of a gas depends on the history of emissions, and (iii) when multiple reservoirs generate time scales quite separate from the traditionally defined lifetime. Proper use of the many "time" parameters in a system, however, gives a very powerful understanding of the response to anthropogenic perturbations.

  11. Large-scale characterization of geologic formations for CO2 injection using Compressed State Kalman Filter

    NASA Astrophysics Data System (ADS)

    Kokkinaki, A.; Li, J. Y.; Zhou, Q.; Birkholzer, J. T.; Kitanidis, P. K.

    2014-12-01

    Carbon dioxide (CO2) storage in deep geologic formations is gaining ground as a potential measure for climate change mitigation. Such storage projects typically operate at large scales (~km), but their performance is often governed by smaller-scale (~m) heterogeneities. The large domain sizes prohibit detailed site characterization and dense monitoring networks, leading to predictions of CO2 migration and trapping based on rough geologic models that cannot capture preferential flow. Kalman Filtering can be used to improve these prior models by assimilating available monitoring data, thereby tracking system performance and reducing prediction uncertainty. However, for large systems with fine discretization, the number of unknowns is in the order of tens of thousands or more, in which case the textbook version of the Kalman Filter has prohibitively expensive computation and storage costs. We present the Compressed State Kalman Filter (CSKF) that can be effectively used for systems with a large number of unknowns to estimate the underlying heterogeneity and to predict the state of interest (e.g., pressure and CO2 saturation). The algorithm's computational efficiency is achieved by using a low-rank approximation of the covariance matrix, as well as a Jacobian-free approach. We demonstrate the estimation and computational performance of our method in a typical CO2 storage scenario with a spatially sparse monitoring network, but with multiple datasets obtained before and during CO2 injection. Our data assimilation framework provides an efficient and practical way to characterize geological formations intended for CO2 injection and storage using monitoring data commonly collected in field applications, as well as to quantify the reduction in uncertainty brought by different types of monitoring data.

  12. Deciphering Time Scale Hierarchy in Reaction Networks.

    PubMed

    Nagahata, Yutaka; Maeda, Satoshi; Teramoto, Hiroshi; Horiyama, Takashi; Taketsugu, Tetsuya; Komatsuzaki, Tamiki

    2016-03-01

    Markovian dynamics on complex reaction networks are one of the most intriguing subjects in a wide range of research fields including chemical reactions, biological physics, and ecology. To represent the global kinetics from one node (corresponding to a basin on an energy landscape) to another requires information on multiple pathways that directly or indirectly connect these two nodes through the entire network. In this paper we present a scheme to extract a hierarchical set of global transition states (TSs) over a discrete-time Markov chain derived from first-order rate equations. The TSs can naturally take into account the multiple pathways connecting any pair of nodes. We also propose a new type of disconnectivity graph (DG) to capture the hierarchical organization of different time scales of reactions that can capture changes in the network due to changes in the time scale of observation. The crux is the introduction of the minimum conductance cut (MCC) in graph clustering, corresponding to the dividing surface across the network having the "smallest" transition probability between two disjoint subnetworks (superbasins on the energy landscape) in the network. We present a new combinatorial search algorithm for finding this MCC. We apply our method to a reaction network of Claisen rearrangement of allyl vinyl ether that consists of 23 nodes and 66 links (saddles on the energy landscape) connecting them. We compare the kinetic properties of our DG to those of the transition matrix of the rate equations and show that our graph can properly reveal the hierarchical organization of time scales in a network. PMID:26641663

  13. Scaling laws from geomagnetic time series

    USGS Publications Warehouse

    Voros, Z.; Kovacs, P.; Juhasz, A.; Kormendi, A.; Green, A.W.

    1998-01-01

    The notion of extended self-similarity (ESS) is applied here for the X - component time series of geomagnetic field fluctuations. Plotting nth order structure functions against the fourth order structure function we show that low-frequency geomagnetic fluctuations up to the order n = 10 follow the same scaling laws as MHD fluctuations in solar wind, however, for higher frequencies (f > l/5[h]) a clear departure from the expected universality is observed for n > 6. ESS does not allow to make an unambiguous statement about the non triviality of scaling laws in "geomagnetic" turbulence. However, we suggest to use higher order moments as promising diagnostic tools for mapping the contributions of various remote magnetospheric sources to local observatory data. Copyright 1998 by the American Geophysical Union.

  14. Accounting for geochemical alterations of caprock fracture permeability in basin-scale models of leakage from geologic CO2 reservoirs

    NASA Astrophysics Data System (ADS)

    Guo, B.; Fitts, J. P.; Dobossy, M.; Bielicki, J. M.; Peters, C. A.

    2012-12-01

    Climate mitigation, public acceptance and energy, markets demand that the potential CO2 leakage rates from geologic storage reservoirs are predicted to be low and are known to a high level of certainty. Current approaches to predict CO2 leakage rates assume constant permeability of leakage pathways (e.g., wellbores, faults, fractures). A reactive transport model was developed to account for geochemical alterations that result in permeability evolution of leakage pathways. The one-dimensional reactive transport model was coupled with the basin-scale Estimating Leakage Semi-Analytical (ELSA) model to simulate CO2 and brine leakage through vertical caprock pathways for different CO2 storage reservoir sites and injection scenarios within the Mt. Simon and St. Peter sandstone formations of the Michigan basin. Mineral dissolution in the numerical reactive transport model expands leakage pathways and increases permeability as a result of calcite dissolution by reactions driven by CO2-acidified brine. A geochemical model compared kinetic and equilibrium treatments of calcite dissolution within each grid block for each time step. For a single fracture, we investigated the effect of the reactions on leakage by performing sensitivity analyses of fracture geometry, CO2 concentration, calcite abundance, initial permeability, and pressure gradient. Assuming that calcite dissolution reaches equilibrium at each time step produces unrealistic scenarios of buffering and permeability evolution within fractures. Therefore, the reactive transport model with a kinetic treatment of calcite dissolution was coupled to the ELSA model and used to compare brine and CO2 leakage rates at a variety of potential geologic storage sites within the Michigan basin. The results are used to construct maps based on the susceptibility to geochemically driven increases in leakage rates. These maps should provide useful and easily communicated inputs into decision-making processes for siting geologic CO2

  15. Time sequence and time scale of intermediate mass fragment emission

    SciTech Connect

    De Filippo, E.; Pagano, A.; Cardella, G.; Lanzano, G.; Papa, M.; Pirrone, S.; Politi, G.; Wilczynski, J.

    2005-04-01

    Semiperipheral collisions in the {sup 124}Sn+{sup 64}Ni reaction at 35 MeV/nucleon were studied using the forward part of the Charged Heavy Ion Mass and Energy Resolving Array. Nearly completely determined ternary events involving projectilelike fragments (PLF), targetlike fragments (TLF), and intermediate mass fragments (IMF) were selected. A new method of studying the reaction mechanism, focusing on the analysis of the correlations between relative velocities in the IMF+PLF and IMF+TLF subsystems, is proposed. The relative velocity correlations provide information on the time sequence and time scale of the neck fragmentation processes leading to production of IMFs. It is shown that the majority of light IMFs are produced within 40-80 fm/c after the system starts to reseparate. Heavy IMFs are formed at times of about 120 fm/c or later and can be viewed as resulting from two-step (sequential) neck rupture processes.

  16. Looking Back to Move Ahead: How Students Learn Geologic Time by Predicting Future Environmental Impacts

    ERIC Educational Resources Information Center

    Zhu, Chen; Rehrey, George; Treadwell, Brooke; Johnson, Claudia C.

    2012-01-01

    This Scholarship of Teaching and Learning project discusses the effectiveness of using distance metaphor-building activities along with a case study exam to help undergraduate nonscience majors understand and apply geologic time. Using action research, we describe how a scholarly teacher integrated previously published and often-used teaching…

  17. Time-lapse motion picture technique applied to the study of geological processes

    USGS Publications Warehouse

    Miller, R.D.; Crandell, D.R.

    1959-01-01

    Light-weight, battery-operated timers were built and coupled to 16-mm motion-picture cameras having apertures controlled by photoelectric cells. The cameras were placed adjacent to Emmons Glacier on Mount Rainier. The film obtained confirms the view that exterior time-lapse photography can be applied to the study of slow-acting geologic processes.

  18. The Treatment of Geological Time & the History of Life on Earth in High School Biology Textbooks

    ERIC Educational Resources Information Center

    Summers, Gerald; Decker, Todd; Barrow, Lloyd

    2007-01-01

    In spite of the importance of geological time in evolutionary biology, misconceptions about historical events in the history of life on Earth are common. Glenn (1990) has documented a decline from 1960 to 1989 in the amount of space devoted to the history of life in high school earth science textbooks, but we are aware of no similar study in…

  19. Large-Scale In-situ Experiments to Determine Geochemical Alterations and Microbial Activities at the Geological Repository

    NASA Astrophysics Data System (ADS)

    Choung, S.; Francis, A. J.; Um, W.; Choi, S.; Kim, S.; Park, J.; Kim, S.

    2013-12-01

    The countries that have generated nuclear power have facing problems on the disposal of accumulated radioactive wastes. Geological disposal method has been chosen in many countries including Korea. A safety issue after the closure of geological repository has been raised, because microbial activities lead overpressure in the underground facilities through gas production. In particular, biodegradable organic materials derived from low- and intermediate-level radioactive wastes play important role on microbial activities in the geological repository. This study performed large scale in-situ experiments using organic wastes and groundwater, and investigated geochemical alteration and microbial activities at early stage (~63 days) as representative of the period, after closure of the geological repository. The geochemical alteration controlled significantly the microorganism types and populations. Database of the biogeochemical alteration facilitates prediction of radionuclides' mobility and establishment of remedial strategy against unpredictable accidents and hazards at early stage right after closure of the geological repository.

  20. Geological conditions of the time of formation of impact craters on Pai-Khoi

    NASA Astrophysics Data System (ADS)

    Mashchak, M. S.

    Present-day ideas on the time of formation of the Kara and Ust-Kara astroblemes are presented, and the main features of the geological structure of Phai-Khoi (the region where these structures are located) are described. Based on an analysis of the geological conditions, a large complex of fossil fauna and diatomaceous algae, and radiological dating of tagamites and impact glasses, it is shown that the craters were formed on the Cretaceous-Paleogene boundary about 66-67 million years ago.

  1. CONSIDERATIONS FOR A REGULATORY FRAMEWORK FOR LARGE-SCALE GEOLOGIC SEQUESTRATION OF CARBON DIOXIDE: A NORTH AMERICAN PERSPECTIVE

    EPA Science Inventory

    Large scale geologic sequestration (GS) of carbon dioxide poses a novel set of challenges for regulators. This paper focuses on the unique needs of large scale GS projects in light of the existing regulatory regimes in the United States and Canada and identifies several differen...

  2. Parametric instabilities in picosecond time scales

    SciTech Connect

    Baldis, H.A.; Rozmus, W.; Labaune, C.; Mounaix, Ph.; Pesme, D.; Baton, S.; Tikhonchuk, V.T.

    1993-03-01

    The coupling of intense laser light with plasmas is a rich field of plasma physics, with many applications. Among these are inertial confinement fusion (ICF), x-ray lasers, particle acceleration, and x-ray sources. Parametric instabilities have been studied for many years because of their importance to ICF; with laser pulses with duration of approximately a nanosecond, and laser intensities in the range 10{sup 14}--10{sup 15}W/cm{sup 2} these instabilities are of crucial concern because of a number of detrimental effects. Although the laser pulse duration of interest for these studies are relatively long, it has been evident in the past years that to reach an understanding of these instabilities requires their characterization and analysis in picosecond time scales. At the laser intensities of interest, the growth rate for stimulated Brillouin scattering (SBS) is of the order of picoseconds, and of an order of magnitude shorter for stimulated Raman scattering (SRS). In this paper the authors discuss SBS and SRS in the context of their evolution in picosecond time scales. They describe the fundamental concepts associated with their growth and saturation, and recent work on the nonlinear treatment required for the modeling of these instabilities at high laser intensities.

  3. Quantifying the imprint of geologic controls on river network topology and scaling in hydrologic response (Invited)

    NASA Astrophysics Data System (ADS)

    Danesh Yazdi, M.; Longjas, A.; Zanardo, S.; Foufoula-Georgiou, E.

    2013-12-01

    River network topology has been at the core of relating geomorphologic and hydrologic properties of landscapes, specifically in developing scaling frameworks of hydrologic fluxes. Recent studies have suggested that the topological structure of river networks might carry the signature of the underlying climatic and/or geologic controls of landscape evolution with implications for regionalization studies and network-based predictive frameworks of hydrologic response. In this study, the drainage networks of 12 sub-watersheds within the Minnesota River Basin (MRB), extracted from the National Hydrography Dataset (NHD), are analyzed in terms of statistical self-similarity in geomorphologic, topologic, and hydrologic attributes. The MRB offers a unique setting for studying fundamental processes of landscape evolution as its geologic history has left behind a still evolving landscape with propagating knickpoints, steep bluffs, strath terraces, and an impressive spatial heterogeneity in river network topology. Preliminary analysis of the MRB sub-watersheds reveals that they do not follow some of the statistical self-similarity relationships usually found in river networks such as the scaling of slopes and lengths with respect to stream order. In addition, the Tokunaga self-similarity analysis shows a wider variability of the higher-order branching parameter c ranging from 1.3 to 2.7, relative to the first-order branching parameter a, which ranges from 0.9 to 1.6. Also, as the Horton-Strahler order of the sub-watersheds increases, a different topology with more regular drainage patterns is observed with lower c values, revealing important connections between geology and network topology. We investigate the hypothesis that sub-watersheds with steeper and still actively incising channels exhibit a pronounced higher-order branching, reflected visually in highly 'feathered' networks and quantitatively in higher values of the Tokunaga parameter c. The frequency of knickpoints

  4. Progress on the development of a three-dimensional capability for simulating large-scale complex geologic processes

    SciTech Connect

    Argueello, J.G.; Stone, C.M.; Fossum, A.F.

    1998-02-01

    Significant progress has been made in developing a three-dimensional capability for predicting the mechanical response of rock over spatial and time scales of geologic interest to the Oil and Gas industry. An Advanced Computational Technology Initiative (ACTI) initiated three years ago to achieve such a computational technology breakthrough has made significant progress towards its goal by adapting and improving the unique advanced quasistatic finite element technology developed by Sandia National Laboratories to the mechanics applications important to exploration and production (E and P). This capability now gives the industry a powerful tool to help reduce risk on prospects, improve pre-project initial reserve estimates, and lower operating costs. Progress to date on this program is reported herein by presenting and discussing the enhancements and adaptations that have been made to the technology, with specific examples to illustrate their use on large E and P geomechanics problems.

  5. On scale and magnitude of pressure build-up induced by large-scale geologic storage of CO2

    SciTech Connect

    Zhou, Q.; Birkholzer, J. T.

    2011-05-01

    The scale and magnitude of pressure perturbation and brine migration induced by geologic carbon sequestration is discussed assuming a full-scale deployment scenario in which enough CO{sub 2} is captured and stored to make relevant contributions to global climate change mitigation. In this scenario, the volumetric rates and cumulative volumes of CO{sub 2} injection would be comparable to or higher than those related to existing deep-subsurface injection and extraction activities, such as oil production. Large-scale pressure build-up in response to the injection may limit the dynamic storage capacity of suitable formations, because over-pressurization may fracture the caprock, may drive CO{sub 2}/brine leakage through localized pathways, and may cause induced seismicity. On the other hand, laterally extensive sedimentary basins may be less affected by such limitations because (i) local pressure effects are moderated by pressure propagation and brine displacement into regions far away from the CO{sub 2} storage domain; and (ii) diffuse and/or localized brine migration into overlying and underlying formations allows for pressure bleed-off in the vertical direction. A quick analytical estimate of the extent of pressure build-up induced by industrial-scale CO{sub 2} storage projects is presented. Also discussed are pressure perturbation and attenuation effects simulated for two representative sedimentary basins in the USA: the laterally extensive Illinois Basin and the partially compartmentalized southern San Joaquin Basin in California. These studies show that the limiting effect of pressure build-up on dynamic storage capacity is not as significant as suggested by Ehlig-Economides and Economides, who considered closed systems without any attenuation effects.

  6. Multispectral Microscopic Imager (MMI): Multispectral Imaging of Geological Materials at a Handlens Scale

    NASA Astrophysics Data System (ADS)

    Farmer, J. D.; Nunez, J. I.; Sellar, R. G.; Gardner, P. B.; Manatt, K. S.; Dingizian, A.; Dudik, M. J.; McDonnell, G.; Le, T.; Thomas, J. A.; Chu, K.

    2011-12-01

    The Multispectral Microscopic Imager (MMI) is a prototype instrument presently under development for future astrobiological missions to Mars. The MMI is designed to be a arm-mounted rover instrument for use in characterizing the microtexture and mineralogy of materials along geological traverses [1,2,3]. Such geological information is regarded as essential for interpreting petrogenesis and geological history, and when acquired in near real-time, can support hypothesis-driven exploration and optimize science return. Correlated microtexure and mineralogy also provides essential data for selecting samples for analysis with onboard lab instruments, and for prioritizing samples for potential Earth return. The MMI design employs multispectral light-emitting diodes (LEDs) and an uncooled focal plane array to achieve the low-mass (<1kg), low-cost, and high reliability (no moving parts) required for an arm-mounted instrument on a planetary rover [2,3]. The MMI acquires multispectral, reflectance images at 62 μm/pixel, in which each image pixel is comprised of a 21-band VNIR spectrum (0.46 to 1.73 μm). This capability enables the MMI to discriminate and resolve the spatial distribution of minerals and textures at the microscale [2, 3]. By extending the spectral range into the infrared, and increasing the number of spectral bands, the MMI exceeds the capabilities of current microimagers, including the MER Microscopic Imager (MI); 4, the Phoenix mission Robotic Arm Camera (RAC; 5) and the Mars Science Laboratory's Mars Hand Lens Imager (MAHLI; 6). In this report we will review the capabilities of the MMI by highlighting recent lab and field applications, including: 1) glove box deployments in the Astromaterials lab at Johnson Space Center to analyze Apollo lunar samples; 2) GeoLab glove box deployments during the 2011 Desert RATS field trials in northern AZ to characterize analog materials collected by astronauts during simulated EVAs; 3) field deployments on Mauna Kea

  7. EDITORIAL: Special issue on time scale algorithms

    NASA Astrophysics Data System (ADS)

    Matsakis, Demetrios; Tavella, Patrizia

    2008-12-01

    This special issue of Metrologia presents selected papers from the Fifth International Time Scale Algorithm Symposium (VITSAS), including some of the tutorials presented on the first day. The symposium was attended by 76 persons, from every continent except Antarctica, by students as well as senior scientists, and hosted by the Real Instituto y Observatorio de la Armada (ROA) in San Fernando, Spain, whose staff further enhanced their nation's high reputation for hospitality. Although a timescale can be simply defined as a weighted average of clocks, whose purpose is to measure time better than any individual clock, timescale theory has long been and continues to be a vibrant field of research that has both followed and helped to create advances in the art of timekeeping. There is no perfect timescale algorithm, because every one embodies a compromise involving user needs. Some users wish to generate a constant frequency, perhaps not necessarily one that is well-defined with respect to the definition of a second. Other users might want a clock which is as close to UTC or a particular reference clock as possible, or perhaps wish to minimize the maximum variation from that standard. In contrast to the steered timescales that would be required by those users, other users may need free-running timescales, which are independent of external information. While no algorithm can meet all these needs, every algorithm can benefit from some form of tuning. The optimal tuning, and even the optimal algorithm, can depend on the noise characteristics of the frequency standards, or of their comparison systems, the most precise and accurate of which are currently Two Way Satellite Time and Frequency Transfer (TWSTFT) and GPS carrier phase time transfer. The interest in time scale algorithms and its associated statistical methodology began around 40 years ago when the Allan variance appeared and when the metrological institutions started realizing ensemble atomic time using more than

  8. EDITORIAL: Special issue on time scale algorithms

    NASA Astrophysics Data System (ADS)

    Matsakis, Demetrios; Tavella, Patrizia

    2008-12-01

    This special issue of Metrologia presents selected papers from the Fifth International Time Scale Algorithm Symposium (VITSAS), including some of the tutorials presented on the first day. The symposium was attended by 76 persons, from every continent except Antarctica, by students as well as senior scientists, and hosted by the Real Instituto y Observatorio de la Armada (ROA) in San Fernando, Spain, whose staff further enhanced their nation's high reputation for hospitality. Although a timescale can be simply defined as a weighted average of clocks, whose purpose is to measure time better than any individual clock, timescale theory has long been and continues to be a vibrant field of research that has both followed and helped to create advances in the art of timekeeping. There is no perfect timescale algorithm, because every one embodies a compromise involving user needs. Some users wish to generate a constant frequency, perhaps not necessarily one that is well-defined with respect to the definition of a second. Other users might want a clock which is as close to UTC or a particular reference clock as possible, or perhaps wish to minimize the maximum variation from that standard. In contrast to the steered timescales that would be required by those users, other users may need free-running timescales, which are independent of external information. While no algorithm can meet all these needs, every algorithm can benefit from some form of tuning. The optimal tuning, and even the optimal algorithm, can depend on the noise characteristics of the frequency standards, or of their comparison systems, the most precise and accurate of which are currently Two Way Satellite Time and Frequency Transfer (TWSTFT) and GPS carrier phase time transfer. The interest in time scale algorithms and its associated statistical methodology began around 40 years ago when the Allan variance appeared and when the metrological institutions started realizing ensemble atomic time using more than

  9. [Geognosy versus Geology: National Modes of Thought and Cultural Practices Concerning Space and Time in Competition].

    PubMed

    Klemun, Marianne

    2015-09-01

    Natural science investigators at the end of the eighteenth century made use of conflicting labels to position their respective preferred fields of activity in the Earth sciences. This mania for labelling marked their break with natural science and the umbrella term 'mineralogy'. In this conflict situation of specialist classifications and explanations, two terms in particular were established: geognosy and geology, which covered the very promising project of research in the areas of the 'origin of the Earth' and the 'formation of the Earth'. These and the associated research goals were subsequently accorded a dazzling career. Proceeding from the conceptual core-meaning in the formation of terms und its semantic spectrum and conceptual shifts in a time of change, my study will look at the identity and heterogeneity functions of geology and geognosy. For whereas in French and English speaking countries the term geology came to be used exclusively (geology, géologie), this was avoided in German, particularly because the term geognosy was preferred. These national differences may be explained with reference to the different cultural and national styles of science: for example the social embedding of geology in the culture of the English gentleman or the French museum culture, and the close connection of 'German' geognosy to mining. A further starting point in the analysis of the double use of both geology and geognosy in German speaking countries until 1840 is provided by the different references to temporalization and spatialization of the two terms. And we should also include the practical implications and the epistemic requirements that were bound up with the defence of geognosy in the German speaking world. PMID:26332067

  10. Earth History databases and visualization - the TimeScale Creator system

    NASA Astrophysics Data System (ADS)

    Ogg, James; Lugowski, Adam; Gradstein, Felix

    2010-05-01

    The "TimeScale Creator" team (www.tscreator.org) and the Subcommission on Stratigraphic Information (stratigraphy.science.purdue.edu) of the International Commission on Stratigraphy (www.stratigraphy.org) has worked with numerous geoscientists and geological surveys to prepare reference datasets for global and regional stratigraphy. All events are currently calibrated to Geologic Time Scale 2004 (Gradstein et al., 2004, Cambridge Univ. Press) and Concise Geologic Time Scale (Ogg et al., 2008, Cambridge Univ. Press); but the array of intercalibrations enable dynamic adjustment to future numerical age scales and interpolation methods. The main "global" database contains over 25,000 events/zones from paleontology, geomagnetics, sea-level and sequence stratigraphy, igneous provinces, bolide impacts, plus several stable isotope curves and image sets. Several regional datasets are provided in conjunction with geological surveys, with numerical ages interpolated using a similar flexible inter-calibration procedure. For example, a joint program with Geoscience Australia has compiled an extensive Australian regional biostratigraphy and a full array of basin lithologic columns with each formation linked to public lexicons of all Proterozoic through Phanerozoic basins - nearly 500 columns of over 9,000 data lines plus hot-curser links to oil-gas reference wells. Other datapacks include New Zealand biostratigraphy and basin transects (ca. 200 columns), Russian biostratigraphy, British Isles regional stratigraphy, Gulf of Mexico biostratigraphy and lithostratigraphy, high-resolution Neogene stable isotope curves and ice-core data, human cultural episodes, and Circum-Arctic stratigraphy sets. The growing library of datasets is designed for viewing and chart-making in the free "TimeScale Creator" JAVA package. This visualization system produces a screen display of the user-selected time-span and the selected columns of geologic time scale information. The user can change the

  11. Time Horizon and Social Scale in Communication

    NASA Astrophysics Data System (ADS)

    Krantz, D. H.

    2010-12-01

    In 2009 our center (CRED) published a first version of The Psychology of Climate Change Communication. In it, we attempted to summarize facts and concepts from psychological research that could help guide communication. While this work focused on climate change, most of the ideas are at least partly applicable for communication about a variety of natural hazards. Of the many examples in this guide, I mention three. Single-action bias is the human tendency to stop considering further actions that might be needed to deal with a given hazard, once a single action has been taken. Another example is the importance of group affiliation in motivating voluntary contributions to joint action. A third concerns the finding that group participation enhances understanding of probabilistic concepts and promotes action in the face of uncertainty. One current research direction, which goes beyond those included in the above publication, focuses on how time horizons arise in the thinking of individuals and groups, and how these time horizons might influence hazard preparedness. On the one hand, individuals sometimes appear impatient, organizations look for immediate results, and officials fail to look beyond the next election cycle. Yet under some laboratory conditions and in some subcultures, a longer time horizon is adopted. We are interested in how time horizon is influenced by group identity and by the very architecture of planning and decision making. Institutional changes, involving long-term contractual relationships among communities, developers, insurers, and governments, could greatly increase resilience in the face of natural hazards. Communication about hazards, in the context of such long-term contractual relationships might look very different from communication that is first initiated by immediate threat. Another new direction concerns the social scale of institutions and of communication about hazards. Traditionally, insurance contracts share risk among a large

  12. Times Scales in Dense Granular Material

    NASA Astrophysics Data System (ADS)

    Zhang, Duan

    2005-07-01

    Forces in dense granular material are transmitted through particle contacts. The evolution of the contact stress is directly related to dynamical interaction forces between particles. Since particle contacts in a dense granular material are random, a statistical method is employed to describe and model their motions. It is found that the time scales of particle contacts determinate stress relaxation and the fluid- like or solid-like behavior of the material. Numerical simulations are performed to calculate statistical properties of particle interactions. Using results from the numerical simulations we examine the relationship between the averaged local deformation field and the macroscopic deformation field. We also examine the relationship between the averaged local interaction force and the averaged stress field in the material. Validities of the Voigt and the Reuss assumptions are examined; and extensions to these assumptions are studied. Numerical simulations show that tangential frictions between particles significantly increase the contact stress, while the direct contribution of the tangential force to the stress is small. This puzzling observation can be explained by dependency of the relaxation time on the tangential friction.

  13. Mastering the Concepts of Geologic Time: Novice Students' Understanding of the Principles of Relative Age

    NASA Astrophysics Data System (ADS)

    Speta, M.; Reid, L.

    2010-12-01

    Misconceptions can adversely affect students’ mastery of the fundamental geoscience concepts necessary for development of the knowledge base required to become a professional geoscientist. In the fall of 2009, in-class learning assessments were introduced into a large (400 student) undergraduate introductory geoscience course to help students develop expert-like problem solving skills for geologic problems. They were also designed to reveal students’ misconceptions on geoscience concepts in order to help direct the course of instruction. These assessments were based on simple, real-world scenarios that geoscientists encounter in their research. One of these assessments focused on the application of concepts of geologic time. It asked students to give the relative ages of granite, schist and shale based on a sketch of two outcrops, and to describe the reasoning behind their answer. In order to test all of the principles of relative age, the assignment had two possible solutions. A post-course analysis of student responses on these assessments was carried out using a modified constant comparative analysis method to identify common misconceptions. This analysis revealed that 61% of students failed to identify both possible solutions. Furthermore, 55% of students applied the principle of superposition to intrusive igneous and metamorphic rocks, and 18% treated the once connected outcrops as having separate geologic histories. 56% of students could not support their proposed geologic history with appropriate reasoning. These results suggest that the principles of relative geologic time that students had the greatest difficulty with were when to apply the principle of superposition and how to apply the principle of original continuity. Students also had difficulty using the principles of relative age to provide appropriate scientific reasoning for their choices.

  14. Issues of scale, location and geologic terrain related to Salt Lake City and Baltimore-Washington metropolitan areas

    USGS Publications Warehouse

    Cleaves, E.T.; Godfrey, A.E.

    2004-01-01

    Planning and development of expanding metropolitan regions require consideration of earth science issues related to issues involving scale, space (location), geologic terrain and physiographic units, and information transfer. This paper explores these matters with examples from the Salt Lake City, Utah area and Mid-Atlantic region of Baltimore-Washington that include water supply and natural hazards (earthquakes, landslides, and sinkholes.) Information transfer methods using physiographic units at national, regional, local and site scales serve to communicate relevant geologic constraint and natural resource information.

  15. Major episodes of geologic change - Correlations, time structure and possible causes

    NASA Technical Reports Server (NTRS)

    Rampino, Michael R.; Caldeira, Ken

    1993-01-01

    Published data sets of major geologic events of the past about 250 Myr (extinction events, sea-level lows, continental flood-basalt eruptions, mountain-building events, abrupt changes in sea-floor spreading, ocean-anoxic and blackshale events and the largest evaporite deposits) have been synthesized (with estimated errors). These events show evidence for a statistically significant periodic component with an underlying periodicity, formally equal to 26.6 Myr, and a recent maximum, close to the present time. The cycle may not be strictly periodic, but a periodicity of about 30 Myr is robust to probable errors in dating of the geologic events. The intervals of geologic change seem to involve jumps in sea-floor spreading associated with episodic continental rifting, volcanism, enhanced orogeny, global sea-level changes and fluctuations in climate. The period may represent a purely internal earth-pulsation, but evidence of planetesimal impacts at several extinction boundaries, and a possible underlying cycle of 28-36 Myr in crater ages, suggests that highly energetic impacts may be affecting global tectonics. A cyclic increase in the flux of planetesimals might result from the passage of the Solar System through the central plane of the Milky Way Galaxy - an event with a periodicity and mean phasing similar to that detected in the geologic changes.

  16. Large-scale geophysical and geological-prospecting earth-crust investigation using high-power electromagnetic pulses

    NASA Astrophysics Data System (ADS)

    Velikhov, E. P.; Panchenko, V. P.

    2005-12-01

    The paper presents the concept and physical/technical prerequisites for the use of multi-megawatt electromagnetic pulses created, for instance, by autonomous MHD facilities of short-term operation (3--12 seconds), in fundamental and applied in-depth geophysical and geological research. Location of geological sites and research regions; circuits and parameters of emitting and detecting devices; unique pulse MHD facilities of 10--100 MWe capacity using solid (powder) fuel, created in Russia; conditions and methods of conducting large-scale experiments and trial methodical works, performed in the last 30 years by a cooperative group of Russian institute in various regions of Russia, Kyrghizia and Tajikistan, are described. Results of the following large-scale experiments and methodical works are presented: Oil and gas deposits' searching (Caspian depression, East Siberia); Study of electric conduction of sediments near and on the sea shelf (Kola peninsula); Electrical prospecting of ore deposits at depths of up to 10 km (Kola peninsula); Study of geo-electrical composition (section) of the earth-crust and upper mantle at the Ural (up to 40 km), and in the Baltic (up to 150 km); Forecasting of earthquakes using the effective electric resistance of earth-crust blocks up to 20 km deep (Tajikistan, Kirghizia); Seismic earth-crust "unloading", and changing the time-dependent distribution of the seismic activity under high-power electromagnetic impact; Impact on the ionosphere and spreading of ultra-low-frequency electromagnetic waves emitted by a high-power source. The possibilities and prospects of research dedicated to developing the technologies for electrical prospecting, sorting and outlining hydrocarbon deposits on the shelf, as well as to monitoring and studying the processes occurring in the earth-crust under artificial high-power electromagnetic impact in seismic regions, are discussed.

  17. First Indications of Intraplate Deformations in Central Germany from Reprocessed GNSS Time Series and Geological Data

    NASA Astrophysics Data System (ADS)

    Becker, Matthias; Leinen, Stefan; Läufer, Gwendolyn; Lehné, Rouwen

    2013-04-01

    Six years of GPS data have been reprocessed in ITRF2008 for a regional SAPOS CORS network in the federal state of Hesse with 25 stations and some anchor sites of IGS and EPN to derive accurate and consistent coordinate time series. Based on daily network solutions coordinate time series parameters like velocities, offsets in case of antenna changes and annual periodic variation have been estimated. The estimation process includes the fitting of a sophisticated stochastic model for the time series which accounts for inherent time correlation. The results are blended with geological data to verify information from geology on potential recent deformations by the geodetic analyses. Besides of some information on the reprocessing of the GNSS the results the stochastics of the derived velocity field will be discussed in detail. Special emphasis will be on the intra-plate deformation: for the horizontal component the residual velocity field after removal of a plate rotation model is presented, while for the vertical velocities the datum-induced systematic effect is removed in order to analyze the remaining vertical motion. The residual velocity field is then matched with the geology for Hesse. Correlation of both vertical and horizontal movements with major geological structures reveals good accordance. SAPOS stations with documented significant subsidence are mainly located in tertiary Graben structures such as the Lower Hessian Basin (station Kassel), the Wetterau (station Kloppenheim) or the Upper Rhine Graben (Station Darmstadt). From the geological point of view these structures are supposed to be subsiding ones. Other major geological features, i.e. the Rhenish Shield as well as the East Hessian Bunter massif are supposed to be affected by recent uplift. SAPOS stations located in these regions match the assumed movement (e.g. Weilburg, Wiesbaden, Bingen, Fulda). Furthermore SAPOS-derived horizontal movements seem to trace tectonic movements in the region, i

  18. Pore-scale imaging of geological carbon dioxide storage under in situ conditions

    NASA Astrophysics Data System (ADS)

    Andrew, Matthew; Bijeljic, Branko; Blunt, Martin J.

    2013-08-01

    While geological carbon dioxide (CO2) storage could contribute to reducing global emissions, it must be designed such that the CO2 cannot escape from the porous rock into which it is injected. An important mechanism to immobilize the CO2, preventing escape, is capillary trapping, where CO2 is stranded as disconnected pore-scale droplets (ganglia) in the rock, surrounded by water. We used X-Ray microtomography to image, at a resolution of 6.4 µm, the pore-scale arrangement and distribution of trapped CO2 clusters in a limestone. We applied high pressures and temperatures typical of a storage formation, while maintaining chemical equilibrium between the CO2, brine, and rock. Substantial amounts of CO2 were trapped, with an average saturation of 0.18. The cluster sizes obeyed a power law distribution, with an exponent of approximately -2.1, consistent with predictions from percolation theory. This work confirms that residual trapping could aid storage security in carbonate aquifers.

  19. Models of the geodynamo over geologic time and the inclination test of the GAD hypothesis

    NASA Astrophysics Data System (ADS)

    Heimpel, M. H.

    2012-12-01

    The assumption that Earth's mean magnetic field has been a geocentric axial dipole (GAD) over geologic time is fundamental to paleomagnetism and plate-tectonics. Previous models have linked inclination distributions to latitudinal heat flow variations (Bloxham, 2000). While verifying and extending those previous results, I show here that radial heat flow structure controls geomagnetic field morphology as well. The inclination test of the GAD hypothesis (Evans,1976) is used to interpret numerical dynamo models, some with latitudinally variable buoyancy flux boundary conditions and others with uniform flux boundary conditions. All of the models are chosen to be Earth-like, and at or near the polarity reversing dynamical regime. As was found in previous work, the global inclination distribution is a function of the buoyancy flux at the core-mantle boundary (CMB). However, I find here that the sign of a latitudinally quadrupolar variable flux condition is critical for dynamo stability. Enhanced polar cooling causes inclination shallowing and tends to stabilize the dynamos to reversals, while enhanced equatorial cooling destabilizes the dynamo, resulting in complex field morphology and high reversal frequency. The uniform flux models represent three convective states of the mantle and core. 1. Present era Earth - likely a typical state of the geodynamo. 2. Global convective overturn, associated with flood basalt volcanism, anomalous magnetic reversal frequency, climate change and mass extinctions. 3. Ancient Earth prior to solid inner core formation. For these uniform flux models the inclination distribution anomaly scales with the relative buoyancy flux at the CMB versus the inner core boundary. Consistent with the CALS10k model of Earth's magnetic field over the past ten millennia (Korte et al., 2011), the present era Earth-like dynamos are GAD-like, with very small time-averaged inclination anomalies. In contrast, the global overturn and ancient Earth dynamos show

  20. Time Scales, Bedforms and Bedload Transport

    NASA Astrophysics Data System (ADS)

    Dhont, B.

    2015-12-01

    Bedload transport rates in mountain streams may exhibit wide fluctuations even under constant flow conditions. A better understanding of bedload pulses is key to predict natural hazards induced by torrential activity and sediment issues in mountainous areas. Several processes such as bedforms migration, grain sorting and random particles' trajectories are evoked as the driving agents of pulse formation and development. Quantifying the effects of these processes is a difficult task. This work aims to investigate the interactions between bedload transport and bedform dynamics in steep gravel-bed rivers. Experiments are carried out in a 17-m long 60-cm wide flume inclined at an angle of 2.7%. The bed is initially flat and made of homogenous natural gravel with a mean diameter of 6 mm. We imposed 200 identical hydrographs (of 1 hr duration) at the flume inlet (the bed surface was not flattened out during these cycling floods). The input hydrograph and the input sediment discharge are nearly triangular. Bed topography is measured after each flood using ultrasound sensors while the bedload transport rate is steadily monitored at the outlet using accelerometers (accelerometers fixed on metallic plates record the impacts of the grains flowing out of the flume). For the sake of comparison, a similar experiment consisting of 19 floods of 10 hours is carried out under constant supply conditions. We show that accelerometers are a cost effective technique to obtain high-frequency bedload discharge data. Spectral analysis of the bedload timeseries is used to highlight the different time scales corresponding to different bedload transport processes. We show that long timeseries are necessary to capture the different processes that drive bedload transport, including the resilience time after a perturbation of the bed. The alternate bars that develop and migrate along the flume are found to significantly influence bedload transport rate fluctuations.

  1. An optimal modification of a Kalman filter for time scales

    NASA Technical Reports Server (NTRS)

    Greenhall, C. A.

    2003-01-01

    The Kalman filter in question, which was implemented in the time scale algorithm TA(NIST), produces time scales with poor short-term stability. A simple modification of the error covariance matrix allows the filter to produce time scales with good stability at all averaging times, as verified by simulations of clock ensembles.

  2. Basin-scale Modeling of Geological Carbon Sequestration: Model Complexity, Injection Scenario and Sensitivity Analysis

    NASA Astrophysics Data System (ADS)

    Huang, X.; Bandilla, K.; Celia, M. A.; Bachu, S.

    2013-12-01

    Geological carbon sequestration can significantly contribute to climate-change mitigation only if it is deployed at a very large scale. This means that injection scenarios must occur, and be analyzed, at the basin scale. Various mathematical models of different complexity may be used to assess the fate of injected CO2 and/or resident brine. These models span the range from multi-dimensional, multi-phase numerical simulators to simple single-phase analytical solutions. In this study, we consider a range of models, all based on vertically-integrated governing equations, to predict the basin-scale pressure response to specific injection scenarios. The Canadian section of the Basal Aquifer is used as a test site to compare the different modeling approaches. The model domain covers an area of approximately 811,000 km2, and the total injection rate is 63 Mt/yr, corresponding to 9 locations where large point sources have been identified. Predicted areas of critical pressure exceedance are used as a comparison metric among the different modeling approaches. Comparison of the results shows that single-phase numerical models may be good enough to predict the pressure response over a large aquifer; however, a simple superposition of semi-analytical or analytical solutions is not sufficiently accurate because spatial variability of formation properties plays an important role in the problem, and these variations are not captured properly with simple superposition. We consider two different injection scenarios: injection at the source locations and injection at locations with more suitable aquifer properties. Results indicate that in formations with significant spatial variability of properties, strong variations in injectivity among the different source locations can be expected, leading to the need to transport the captured CO2 to suitable injection locations, thereby necessitating development of a pipeline network. We also consider the sensitivity of porosity and

  3. LUCI: A facility at DUSEL for large-scale experimental study of geologic carbon sequestration

    SciTech Connect

    Peters, C. A.; Dobson, P.F.; Oldenburg, C.M.; Wang, J. S. Y.; Onstott, T.C.; Scherer, G.W.; Freifeld, B.M.; Ramakrishnan, T.S.; Stabinski, E.L.; Liang, K.; Verma, S.

    2010-10-01

    LUCI, the Laboratory for Underground CO{sub 2} Investigations, is an experimental facility being planned for the DUSEL underground laboratory in South Dakota, USA. It is designed to study vertical flow of CO{sub 2} in porous media over length scales representative of leakage scenarios in geologic carbon sequestration. The plan for LUCI is a set of three vertical column pressure vessels, each of which is {approx}500 m long and {approx}1 m in diameter. The vessels will be filled with brine and sand or sedimentary rock. Each vessel will have an inner column to simulate a well for deployment of down-hole logging tools. The experiments are configured to simulate CO{sub 2} leakage by releasing CO{sub 2} into the bottoms of the columns. The scale of the LUCI facility will permit measurements to study CO{sub 2} flow over pressure and temperature variations that span supercritical to subcritical gas conditions. It will enable observation or inference of a variety of relevant processes such as buoyancy-driven flow in porous media, Joule-Thomson cooling, thermal exchange, viscous fingering, residual trapping, and CO{sub 2} dissolution. Experiments are also planned for reactive flow of CO{sub 2} and acidified brines in caprock sediments and well cements, and for CO{sub 2}-enhanced methanogenesis in organic-rich shales. A comprehensive suite of geophysical logging instruments will be deployed to monitor experimental conditions as well as provide data to quantify vertical resolution of sensor technologies. The experimental observations from LUCI will generate fundamental new understanding of the processes governing CO{sub 2} trapping and vertical migration, and will provide valuable data to calibrate and validate large-scale model simulations.

  4. Towards a stable numerical time scale for the early Paleogene

    NASA Astrophysics Data System (ADS)

    Hilgen, Frederik; Kuiper, Klaudia; Sierro, Francisco J.; Wotzlaw, Jorn; Schaltegger, Urs; Sahy, Diana; Condon, Daniel

    2014-05-01

    The construction of an astronomical time scale for the early Paleogene is hampered by ambiguities in the number, correlation and tuning of 405-kyr eccentricity related cycles in deep marine records from ODP cores and land-based sections. The two most competing age models result in astronomical ages for the K/Pg boundary that differ by ~750 kyr (~66.0 Ma of Vandenberghe et al. (2012) versus 65.25 Ma of Westerhold et al. (2012); these ages in turn are consistent with proposed ages for the Fish Canyon sanidine (FCs) that differ by ~300 kyr (28.201 Ma of Kuiper et al. (2008) versus 27.89 Ma of Westerhold et al. (2012)); an even older age of 28.294 Ma is proposed based on a statistical optimization model (Renne et al., 2011). The astronomically calibrated FCs age of 28.201 ± 0.046 Ma of Kuiper et al. (2008), which is consistent with the astronomical age of ~66.0 Ma for the K/Pg boundary, is currently adopted in the standard geological time scale (GTS2012). Here we combine new and published data in an attempt to solve the controversy and arrive at a stable nuemrical time scale for the early Paleogene. Supporting their younger age model, Westerhold et al. (2012) argue that the tuning of Miocene sections in the Mediterranean, which underlie the older FCs age of Kuiper et al. (2008) and, hence, the coupled older early Paleogene age model of Vandenberghe et al. (2012), might be too old by three precession cycles. We thoroughly rechecked this tuning; distinctive cycle patterns related to eccentricity and precession-obliquity interference make a younger tuning that would be consistent with the younger astronomical age of 27.89 Ma for the FCs of Westerhold et al. (2012) challenging. Next we compared youngest U/Pb zircon and astronomical ages for a number of ash beds in the tuned Miocene section of Monte dei Corvi. These ages are indistinguishable, indicating that the two independent dating methods yield the same age when the same event is dated. This is consistent with results

  5. Detection of crossover time scales in multifractal detrended fluctuation analysis

    NASA Astrophysics Data System (ADS)

    Ge, Erjia; Leung, Yee

    2013-04-01

    Fractal is employed in this paper as a scale-based method for the identification of the scaling behavior of time series. Many spatial and temporal processes exhibiting complex multi(mono)-scaling behaviors are fractals. One of the important concepts in fractals is crossover time scale(s) that separates distinct regimes having different fractal scaling behaviors. A common method is multifractal detrended fluctuation analysis (MF-DFA). The detection of crossover time scale(s) is, however, relatively subjective since it has been made without rigorous statistical procedures and has generally been determined by eye balling or subjective observation. Crossover time scales such determined may be spurious and problematic. It may not reflect the genuine underlying scaling behavior of a time series. The purpose of this paper is to propose a statistical procedure to model complex fractal scaling behaviors and reliably identify the crossover time scales under MF-DFA. The scaling-identification regression model, grounded on a solid statistical foundation, is first proposed to describe multi-scaling behaviors of fractals. Through the regression analysis and statistical inference, we can (1) identify the crossover time scales that cannot be detected by eye-balling observation, (2) determine the number and locations of the genuine crossover time scales, (3) give confidence intervals for the crossover time scales, and (4) establish the statistically significant regression model depicting the underlying scaling behavior of a time series. To substantive our argument, the regression model is applied to analyze the multi-scaling behaviors of avian-influenza outbreaks, water consumption, daily mean temperature, and rainfall of Hong Kong. Through the proposed model, we can have a deeper understanding of fractals in general and a statistical approach to identify multi-scaling behavior under MF-DFA in particular.

  6. Insights into soil carbon dynamics across climatic and geologic gradients from time-series and fraction-specific radiocarbon analysis

    NASA Astrophysics Data System (ADS)

    van der Voort, Tessa Sophia; Hagedorn, Frank; Zell, Claudia; McIntyre, Cameron; Eglinton, Tim

    2016-04-01

    Understanding the interaction between soil organic matter (SOM) and climatic, geologic and ecological factors is essential for the understanding of potential susceptibility and vulnerability to climate and land use change. Radiocarbon constitutes a powerful tool for unraveling SOM dynamics and is increasingly used in studies of carbon turnover. The complex and inherently heterogeneous nature of SOM renders it challenging to assess the processes that govern SOM stability by solely looking at the bulk signature on a plot-scale level. This project combines bulk radiocarbon measurements on a regional-scale spanning wide climatic and geologic gradients with a more in-depth approach for a subset of locations. For this subset, time-series and carbon pool-specific radiocarbon data has been acquired for both topsoil and deeper soils. These well-studied sites are part of the Long-Term Forest Ecosystem Research (LWF) program of the Swiss Federal Institute for Forest, Snow and Landscape research (WSL). Statistical analysis was performed to examine relationships of radiocarbon signatures with variables such as temperature, precipitation and elevation. Bomb-curve modeling was applied determine carbon turnover using time-series data. Results indicate that (1) there is no significant correlation between Δ14C signature and environmental conditions except a weak positive correlation with mean annual temperature, (2) vertical gradients in Δ14C signatures in surface and deeper soils are highly similar despite covering disparate soil-types and climatic systems, and (3) radiocarbon signatures vary significantly between time-series samples and carbon pools. Overall, this study provides a uniquely comprehensive dataset that allows for a better understanding of links between carbon dynamics and environmental settings, as well as for pool-specific and long-term trends in carbon (de)stabilization.

  7. Time scales in Galveston Bay: An unsteady estuary

    NASA Astrophysics Data System (ADS)

    Rayson, Matthew D.; Gross, Edward S.; Hetland, Robert D.; Fringer, Oliver B.

    2016-04-01

    Estuarine time scales including the turnover, particle e-folding time, the age (calculated with a passive tracer), and residence time (calculated with Lagrangian particles) were computed using a three-dimensional hydrodynamic model of Galveston Bay, a low-flow, partially stratified estuary. Time scales were computed during a time period when river flow varied by several orders of magnitude and all time scales therefore exhibited significant temporal variability because of the unsteadiness of the system. The spatial distributions of age and residence time were qualitatively similar and increased from 15 days in a shipping channel to >45 days in the upper estuary. Volume-averaged age and residence time decreased during high-flow conditions. Bulk time scales, including the freshwater and salinity turnover times, were far more variable due to the changing river discharge and salt flux through the estuary mouth. A criterion for calculating a suitable averaging time is discussed to satisfy a steady state assumption and to estimate a more representative bulk time scale. When scaled with a freshwater advective time, all time scales were approximately equal to the advective time scale during high-flow conditions and many times higher during low-flow conditions. The mean age, Lagrangian residence, and flushing times exhibited a relationship that was weakly dependent on the freshwater advective time scale demonstrating predictability even in an unsteady, realistic estuary.

  8. Pore-scale study of capillary trapping mechanism during CO2 injection in geological formations

    SciTech Connect

    Bandara, Uditha C.; Tartakovsky, Alexandre M.; Palmer, Bruce J.

    2011-11-01

    Geological sequestration of CO{sub 2} gas emerged as a promising solution for reducing amount of green house gases in atmosphere. A number of continuum scale models are available to describe the transport phenomena of CO{sub 2} sequestration. These models rely heavily on a phenomenological description of subsurface transport phenomena and the predictions can be highly uncertain. Pore-scale models provide a better understanding of fluid displacement processes, nonetheless such models are rare. In this work we use a Smoothed Particle Hydrodynamics (SPH) model to study pore-scale displacement and capillary trapping mechanisms of super-critical CO{sub 2} in the subsurface. Simulations are carried out to investigate the effects of gravitational, viscous, and capillary forces in terms of Gravity, Capillary, and Bond numbers. Contrary to the other published continuum scale investigations, we found that not only Gravity number but also Capillary number plays an important role on the fate of injected CO{sub 2}. For large Gravity numbers (on the order of 10), most of the injected CO{sub 2} reaches the cap-rock due to gravity segregation. A significant portion of CO{sub 2} gets trapped by capillary forces when Gravity number is small (on the order of 0.1). When Gravity number is moderately high (on the order of 1), trapping patterns are heavily dependent on Capillary number. If Capillary number is very small (less than 0.001), then capillary forces dominate the buoyancy forces and a significant fraction of injected CO{sub 2} is trapped by the capillary forces. Conversely, if Capillary number is high (higher than 0.001), capillary trapping is relatively small since buoyancy dominates the capillary forces. In addition, our simulations reveal different types of capillary trapping and flow displacement mechanisms during and after injection. In gravity dominated cases leave behind was the widespread trapping mechanism. Division was the primary trapping mechanism in viscous

  9. The geospatial relationship of geologic strata, geological fractures, and land use attained by a time-series aridity index in a semiarid region.

    PubMed

    Rodríguez-Moreno, Victor M; Kretzschmar, Thomas G; Padilla-Ramírez, J Saúl

    2015-07-01

    In a vast semiarid region of the Baja California Peninsula, remote sensing and GIS techniques were applied to moderate resolution images of Landsat 5 TM to explore the geospatial correlation among the grid aridity index (AI), shapefiles of geologic strata, land use, and geological fractures. A dataset of randomized sample points in a time-series of one hydrologic year along with vector file GIS delineated geologic fractures-including the area between their left/right parallel buffer lines-was used as mask analysis. MANOVA results were significant (p < 0.05) for geologic strata, land use, and basin. Overall results reveal the effects of soil texture on water retention on deeper soil horizons and the rate of vertical motion of rainwater. Despite the fact that geologic fractures underlie a large number of biotic communities, in both latitude and longitude gradients of the peninsula, no statistical significance was observed among the fractures themselves or the areas between their parallel buffer lines. One pulse rainfall event was documented by the AI grid maps enabling a robust vegetative response in early summer to an abnormal amount of rain provided by tropical storm Julio. AI grids appear to be useful for characterizing an ecosystem's dynamism. New options are suggested for this research strategy by expanding the number of datasets and incorporating geographic exclusion areas. PMID:26095900

  10. A Quaternary Geomagnetic Instability Time Scale

    NASA Astrophysics Data System (ADS)

    Singer, B. S.

    2013-12-01

    Reversals and excursions of Earth's geomagnetic field create marker horizons that are readily detected in sedimentary and volcanic rocks worldwide. An accurate and precise chronology of these geomagnetic field instabilities is fundamental to understanding several aspects of Quaternary climate, dynamo processes, and surface processes. For example, stratigraphic correlation between marine sediment and polar ice records of climate change across the cryospheres benefits from a highly resolved record of reversals and excursions. The temporal patterns of dynamo behavior may reflect physical interactions between the molten outer core and the solid inner core or lowermost mantle. These interactions may control reversal frequency and shape the weak magnetic fields that arise during successive dynamo instabilities. Moreover, weakening of the axial dipole during reversals and excursions enhances the production of cosmogenic isotopes that are used in sediment and ice core stratigraphy and surface exposure dating. The Geomagnetic Instability Time Scale (GITS) is based on the direct dating of transitional polarity states recorded by lava flows using the 40Ar/39Ar method, in parallel with astrochronologic age models of marine sediments in which O isotope and magnetic records have been obtained. A review of data from Quaternary lava flows and sediments yields a GITS comprising 10 polarity reversals and 27 excursions during the past 2.6 million years. Nine of the ten reversals bounding chrons and subchrons are associated with 40Ar/39Ar ages of transitionally-magnetized lava flows. The tenth, the Guass-Matuyama chron boundary, is tightly bracketed by 40Ar/39Ar dated ash deposits. Of the 27 well-documented excursions, 14 occurred during the Matuyama chron and 13 during the Brunhes chron; 19 have been dated directly using the 40Ar/39Ar method on transitionally-magnetized volcanic rocks and form the backbone of the GITS. Excursions are clearly not the rare phenomena once thought

  11. An integrated experimental program to understanding leakage from geologic carbon sequestration sites across scales

    NASA Astrophysics Data System (ADS)

    Clarens, A. F.; Wang, S.; Liang, B.; Peters, C. A.; Fitts, J. P.; Deng, H.; Ellis, B. R.

    2012-12-01

    Leakage from the deep saline aquifers targeted in geologic carbon sequestration (GCS) is difficult to study because of heterogeneities in the structure and chemical composition of the subsurface along with the characteristically large length scales and resulting phase changes that are involved. The chemical and physical processes that govern the buoyancy driven flow of CO2 are important to understand because leakage could undermine the nominal goal of GCS to keep CO2 out of the atmosphere. Here we report on a partnership between Princeton and the University of Virginia (UVa) to study these processes experimentally across multiple length scales in both porous media and fractured caprocks. Experiments span length scales from microns to meters, and the processes studied range from geochemical reactions to the physics of flow. In this presentation, we summarize the suite of experiments that are underway and present recent findings. We seek to demonstrate that this coordinated, multi-disciplinary, multi-scale research collaboration will lead to improved understanding of the fundamental processes that may control the permanence of stored CO2. At UVa, the aim has been to characterize the interfacial properties that will impact buoyancy driven flows in porous media. Contact angle experiments at the CO2-brine-mineral interface have been carried out on silica, carbonate and clay minerals. These results will be used to inform how mineral heterogeneity influences multiphase buoyant flow through sandstones in which pore surfaces are frequently coated by diagenetic clays. Although all minerals are water wetting, the pH point of zero charge was found to be a good predictor of maximum wetting for a solid surface. When the CO2 was not in equilibrium with the brine, hysteric effects were observed as CO2 dissolved into the bulk fluid. Some of this is associated with contact line pinning on certain surfaces that may be driven by salt precipitation near the phase interface. Contact

  12. Relationship Between the Surface Area to Volume Ratio and Temperature across Geologic Time in Ostracods

    NASA Astrophysics Data System (ADS)

    Jackson, C.; Zaroff, S.; Heim, N. A.; Payne, J.

    2014-12-01

    In 1877 Joseph Allen proposed that endothermic terrestrial organisms would have lower surface area to volume ratios (SAVR) in colder climates and higher SAVRs in warmer climates. With a smaller surface area compared to volume, organisms can retain more heat in cold climates. We tested to see if this principle applied to ostracods, a type of ectothermic marine invertebrate. We hypothesised that Allen's rule applies to ostracods, as Allen's rule has been demonstrated in frogs (Alho 2011), which are also ectotherms . We used the linear dimensions of the three major carapace axes of ostracod holotypes to estimate the SAVR. We compared ostracod SAVRs with paleotemperatures from Royer et al. (2004). We found that there was a correlation between surface area and temperature; it is a small, but statistically significant correlation (adj. R2=0.0167). This means that as temperature increased, the SAVR also increased. We also found a negative correlation between ostracod SAVR to geologic time(adj. R2=0.0114), which shows us that as time has gone on, ostracod SAVR has decreased. We then plotted the correlation coefficient of SAVR to temperature over geologic time to explore trends in the strength of Allen's rule. For most of time there was no relationship but during the Devonian, Allen's Rule did explain the trend. In short, temperature does explain some of the correlation between the SAVR and temperature, but it is likely there were other environmental factors affecting this relationship.

  13. Large-Scale Digital Geologic Map Databases and Reports of the North Coal District in Afghanistan

    USGS Publications Warehouse

    Hare, Trent M.; Davis, Philip A.; Nigh, Devon; Skinner, James A.; SanFilipo, John R.; Bolm, Karen S.; Fortezzo, Corey M.; Galuszka, Donna; Stettner, William R.; Sultani, Shafiqullah; Nader, Billal

    2008-01-01

    members of the coal team: Engineer Saifuddin Aminy (Team Leader); Engineer Gul Pacha Azizi; Engineer Abdul Haq Barakati; Engineer Abdul Basir; Engineer Mohammad Daoud; Engineer Abdullah Ebadi; Engineer Abdul Ahad Omaid; Engineer Spozmy; and Engineer Shapary Tokhi. The ongoing efforts of Engineer Mir M. Atiq Kazimi (Team leader); Engineer M. Anwar Housinzada; and Engineer Shereen Agha of the AGS Records Department to organize and catalogue the AGS material were invaluable in locating and preserving these data. The efforts of the entire AGS staff to personally preserve these data during war time, in the absence of virtually any supporting infrastructure, was truly remarkable. The efforts by the British Geological Survey (BGS) to assist the AGS in archiving these data, and the personal assistance provided by BGS (notably Robert McIntosh), to the USGS teams were also appreciated. The logistical support provided by the U.S. Embassy in Kabul, particularly the Afghanistan Reconstruction Group, was critical to the success of the USGS teams while in Afghanistan. Finally, the efforts of the Minister of the Ministry of Mines and Industries (M. Ibrahim Adel) to support the USGS coal resource assessment in Afghanistan, in both his current and former role as President of the Mines Affairs Department was vital to this effort.

  14. U. S. GEOLOGICAL SURVEY'S NATIONAL REAL-TIME HYDROLOGIC INFORMATION SYSTEM USING GOES SATELLITE TECHNOLOGY.

    USGS Publications Warehouse

    Shope, William G., Jr.

    1987-01-01

    The U. S. Geological Survey maintains the basic hydrologic data collection system for the United States. The Survey is upgrading the collection system with electronic communications technologies that acquire, telemeter, process, and disseminate hydrologic data in near real-time. These technologies include satellite communications via the Geostationary Operational Environmental Satellite, Data Collection Platforms in operation at over 1400 Survey gaging stations, Direct-Readout Ground Stations at nine Survey District Offices and a network of powerful minicomputers that allows data to be processed and disseminate quickly.

  15. On time scales and time synchronization using LORAN-C as a time reference signal

    NASA Technical Reports Server (NTRS)

    Chi, A. R.

    1974-01-01

    The long term performance of the eight LORAN-C chains is presented in terms of the Coordinated Universal Time (UTC) of the U.S. Naval Observatory (USNO); and the use of the LORAN-C navigation system for maintaining the user's clock to a UTC scale is described. The atomic time scale and the UTC of several national laboratories and observatories relative to the international atomic time are reported. Typical performance of several NASA tracking station clocks, relative to the USNO master clock, is also presented.

  16. How Conoco uses GIS technology to map geology, geography through time

    SciTech Connect

    Foley, D.C.; Ghazi, T.Y.

    1995-05-08

    Conoco Inc.`s Advanced Exploration Organization (AEO) is in the business of studying foreign sedimentary basins from a regional perspective to evaluate their potential for petroleum exploration. Recently the company decided to focus some of the AEO`s resources on developing a global ranking system for those areas of the world where hydrocarbons might occur. AEO obtained software from the University of Texas, Arlington that rotates continents or portions of continents through time. Using the software, company geoscientists have created a series of maps, known as a PaleoAtlas, that depicts the geography and selected geological features for different periods in Phanerozoic time. In addition, the AEO has developed a software package based on ARC/INFO (ESRI Inc., Redlands, Calif.), a commercial GIS platform, to manage, integrate, and analyze those time-slice maps. Entitled PaleoAtlas Geographic Evaluation system (Pages), this software also sequences portions of the maps in a montage effect that geoscientists can use to study the geological evolution of petroleum source rocks. The paper describes the AEO project and its software.

  17. Coda-wave interferometry analysis of time-lapse VSP data for monitoring geological carbon sequestration

    SciTech Connect

    Zhou, R.; Huang, L.; Rutledge, J.T.; Fehler, M.; Daley, T.M.; Majer, E.L.

    2009-11-01

    Injection and movement/saturation of carbon dioxide (CO2) in a geological formation will cause changes in seismic velocities. We investigate the capability of coda-wave interferometry technique for estimating CO2-induced seismic velocity changes using time-lapse synthetic vertical seismic profiling (VSP) data and the field VSP datasets acquired for monitoring injected CO2 in a brine aquifer in Texas, USA. Synthetic VSP data are calculated using a finite-difference elastic-wave equation scheme and a layered model based on the elastic Marmousi model. A possible leakage scenario is simulated by introducing seismic velocity changes in a layer above the CO2 injection layer. We find that the leakage can be detected by the detection of a difference in seismograms recorded after the injection compared to those recorded before the injection at an earlier time in the seismogram than would be expected if there was no leakage. The absolute values of estimated mean velocity changes, from both synthetic and field VSP data, increase significantly for receiver positions approaching the top of a CO2 reservoir. Our results from field data suggest that the velocity changes caused by CO2 injection could be more than 10% and are consistent with results from a crosswell tomogram study. This study demonstrates that time-lapse VSP with coda-wave interferometry analysis can reliably and effectively monitor geological carbon sequestration.

  18. Linking Response-Time Parameters onto a Common Scale

    ERIC Educational Resources Information Center

    van der Linden, Wim J.

    2010-01-01

    Although response times on test items are recorded on a natural scale, the scale for some of the parameters in the lognormal response-time model (van der Linden, 2006) is not fixed. As a result, when the model is used to periodically calibrate new items in a testing program, the parameter are not automatically mapped onto a common scale. Several…

  19. Nitrate reduction in geologically heterogeneous catchments--a framework for assessing the scale of predictive capability of hydrological models.

    PubMed

    Refsgaard, Jens Christian; Auken, Esben; Bamberg, Charlotte A; Christensen, Britt S B; Clausen, Thomas; Dalgaard, Esben; Effersø, Flemming; Ernstsen, Vibeke; Gertz, Flemming; Hansen, Anne Lausten; He, Xin; Jacobsen, Brian H; Jensen, Karsten Høgh; Jørgensen, Flemming; Jørgensen, Lisbeth Flindt; Koch, Julian; Nilsson, Bertel; Petersen, Christian; De Schepper, Guillaume; Schamper, Cyril; Sørensen, Kurt I; Therrien, Rene; Thirup, Christian; Viezzoli, Andrea

    2014-01-15

    In order to fulfil the requirements of the EU Water Framework Directive nitrate load from agricultural areas to surface water in Denmark needs to be reduced by about 40%. The regulations imposed until now have been uniform, i.e. the same restrictions for all areas independent of the subsurface conditions. Studies have shown that on a national basis about 2/3 of the nitrate leaching from the root zone is reduced naturally, through denitrification, in the subsurface before reaching the streams. Therefore, it is more cost-effective to identify robust areas, where nitrate leaching through the root zone is reduced in the saturated zone before reaching the streams, and vulnerable areas, where no subsurface reduction takes place, and then only impose regulations/restrictions on the vulnerable areas. Distributed hydrological models can make predictions at grid scale, i.e. at much smaller scale than the entire catchment. However, as distributed models often do not include local scale hydrogeological heterogeneities, they are typically not able to make accurate predictions at scales smaller than they are calibrated. We present a framework for assessing nitrate reduction in the subsurface and for assessing at which spatial scales modelling tools have predictive capabilities. A new instrument has been developed for airborne geophysical measurements, Mini-SkyTEM, dedicated to identifying geological structures and heterogeneities with horizontal and lateral resolutions of 30-50 m and 2m, respectively, in the upper 30 m. The geological heterogeneity and uncertainty are further analysed by use of the geostatistical software TProGS by generating stochastic geological realisations that are soft conditioned against the geophysical data. Finally, the flow paths within the catchment are simulated by use of the MIKE SHE hydrological modelling system for each of the geological models generated by TProGS and the prediction uncertainty is characterised by the variance between the

  20. US GEOLOGICAL SURVEY'S NATIONAL SYSTEM FOR PROCESSING AND DISTRIBUTION OF NEAR REAL-TIME HYDROLOGICAL DATA.

    USGS Publications Warehouse

    Shope, William G., Jr.

    1987-01-01

    The US Geological Survey is utilizing a national network of more than 1000 satellite data-collection stations, four satellite-relay direct-readout ground stations, and more than 50 computers linked together in a private telecommunications network to acquire, process, and distribute hydrological data in near real-time. The four Survey offices operating a satellite direct-readout ground station provide near real-time hydrological data to computers located in other Survey offices through the Survey's Distributed Information System. The computerized distribution system permits automated data processing and distribution to be carried out in a timely manner under the control and operation of the Survey office responsible for the data-collection stations and for the dissemination of hydrological information to the water-data users.

  1. Mars Eolian Geology at Airphoto Scales: The Large Wind Streaks of Western Arabia Terra

    NASA Technical Reports Server (NTRS)

    Edgett, Kenneth S.

    2001-01-01

    More than 27,000 pictures at aerial photograph scales (1.5-12 m/pixel) have been acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) since September 1997. The pictures are valuable for testing hypotheses about geologic history and processes of Mars. Of particular interest are eolian features connected to surface albedo patterns. This work is focused on low-albedo wind streaks, some over 100 km long, in western Arabia Terra. Each streak is widest where it originates at an impact crater (typically 25-150 km diameter). The streaks taper downwind. Within the associated craters there is a lower-albedo surface that, in nearly all observed cases, includes barchan dunes indicative of transport in the same direction as the wind streaks. Upwind of the dunes there is usually an outcrop of layered material that might have served as a source for dune sand. MOC images show that the west Arabia streaks consist of a smooth-surfaced, multiple-meters-thick, mantle (smooth at 1.5 m/pixel) that appears to be superposed on local surfaces. No dunes are present, indicating that down-streak transport of sediment via saltation and traction have not occurred. Two models might explain the observed properties: (1) the streaks consist of dark silt- and clay-sized grains deflated from the adjacent crater interiors and deposited from suspension or (2) they are remnants (protected in the lee of impact crater rims) of a formerly much larger, regional covering of low albedo, smooth-surfaced mantle. The latter hypothesis is based on observation of low albedo mantled surfaces occurring south of west Arabia in Terra Meridiani. For reasons yet unknown, a large fraction of the martian equatorial regions are covered by low albedo, mesa-forming material that lies unconformably atop eroded layered and cratered terrain. Both hypotheses are being explored via continued selective targeting of new MOC images as well as analyses of the new data.

  2. Continued Investigations of the Accretion History of Extraterrestrial Matter over Geologic Time

    NASA Technical Reports Server (NTRS)

    Farley, Kenneth

    2001-01-01

    This grant supported our ongoing project to characterize the accretion rate of interplanetary dust particles (IDPs) to Earth over geologic time using He-3 as a tracer. IDPs are derived from collisions in the asteroid belt and from disaggregation of active comets. Owing to their small size (few to few hundred micrometers diameter) these particles spiral into the sun under Poynting-Robertson drag typically in less than a few tens of kyrs. Thus IDPs must be continually resupplied to the zodiacal cloud, and because the processes of IDP production are likely to be sporadic, time variation in the IDP accretion rate to Earth is likely to be time-varying. For example, major asteroidal collisions and comet showers should greatly enhance the IDP accretion rate. Our ultimate objective (still ongoing) is to document this time variance so as to better understand the history of the solar system, the source of IDPs accreting to Earth, and the details of the mechanism by which particles are captured by Earth. To document variations in IDP accretion rate through time we use He-3 as a tracer. This isotope is in extremely low abundance in terrestrial matter, but IDPs have very high concentrations of He-3 from implantation of solar wind ions. By measuring He-3 in seafloor sediments, we can estimate the IDP accretion rate for at least the last few hundred Myrs. Under an earlier NASA grant we identified the existence of a large increase in He-3 flux in the Late Eocene (35 Myr ago), coincident with the two largest impact craters of the Cenozoic Era. The simplest interpretation of this observation is the occurrence of a shower of long period comets at that time, simultaneously increasing the impact cratering probability and accretion rate of IDPs to Earth (Farley et al., 1998). Comet showers produced by stellar perturbation of the Oort cloud should be fairly common in the geologic record, so this is not an unreasonable interpretation of our observations.

  3. Detecting separate time scales in genetic expression data

    PubMed Central

    2010-01-01

    Background Biological processes occur on a vast range of time scales, and many of them occur concurrently. As a result, system-wide measurements of gene expression have the potential to capture many of these processes simultaneously. The challenge however, is to separate these processes and time scales in the data. In many cases the number of processes and their time scales is unknown. This issue is particularly relevant to developmental biologists, who are interested in processes such as growth, segmentation and differentiation, which can all take place simultaneously, but on different time scales. Results We introduce a flexible and statistically rigorous method for detecting different time scales in time-series gene expression data, by identifying expression patterns that are temporally shifted between replicate datasets. We apply our approach to a Saccharomyces cerevisiae cell-cycle dataset and an Arabidopsis thaliana root developmental dataset. In both datasets our method successfully detects processes operating on several different time scales. Furthermore we show that many of these time scales can be associated with particular biological functions. Conclusions The spatiotemporal modules identified by our method suggest the presence of multiple biological processes, acting at distinct time scales in both the Arabidopsis root and yeast. Using similar large-scale expression datasets, the identification of biological processes acting at multiple time scales in many organisms is now possible. PMID:20565716

  4. 1:75K-Scale Geologic Mapping of Southwestern Melas Chasma, Mars

    NASA Astrophysics Data System (ADS)

    Edgar, L. A.; Skinner, J. A.

    2016-06-01

    The goal of this work is to document the geologic evolution of southwestern Melas Chasma, and to place localized observations into a broader, standardized context for comparison to other similar regions within the Valles Marineris basin system.

  5. Geological environment of karst within chalk using airborne time domain electromagnetic data cross-interpreted with boreholes

    NASA Astrophysics Data System (ADS)

    Reninger, P.-A.; Martelet, G.; Lasseur, E.; Beccaletto, L.; Deparis, J.; Perrin, J.; Chen, Y.

    2014-07-01

    The ability of airborne Time Domain ElectroMagnetic (TDEM) to image plurikilometric chalk heterogeneities and its implications for the development of a karstic system is addressed in this study. A heliborne TDEM survey was conducted around Courtenay (France) over the Paris Basin Upper Cretaceous chalk. This aquifer is known as a highly weathered and karstified horizon both strongly modify chalk petrophysical properties. Numerous boreholes and one recently reprocessed seismic line were used in order to strengthen TDEM interpretations. We performed cross statistics between boreholes and the resistivity model. This allowed defining empirical resistivity ranges corresponding to the main geological formations within the area. We were therefore able to map large scale heterogeneities in the chalk over the study area. First, the TDEM method highlighted probable weathering corridors in the chalk, related to the tectonic activity, consistent with faults previously interpreted in the seismics at deeper levels. Second, it was possible to image a large scale undulating geometry in the chalk with a SW-NE orientation, this direction is consistent throughout the Paris Basin, and well defined on the cliffs of Normandy (Channel coast, north of France). This geometry has revealed two separate chalk deposits C1 and C2 in Courtenay area: C1 is more resistive than C2. The resistivity model has then been compared to piezometric measurements acquired as part of previous hydrological studies. The karstic drainage appears to be developed within C1 chalk deposit and most of the piezometric domes seem to be associated to intermediate resistivity zones in C1, interpreted as weathered. According to the results obtained from this study, we were able to suggest a geological framework for the development of Courtenay karstic system.

  6. On the nature of gravity and possible change of Earth mass during geological time

    NASA Astrophysics Data System (ADS)

    Sapunov, Valentin

    2015-04-01

    A number of circumstances can't be explained based on view of the constant force of gravity on the Earth: 1. Dimensions of fossil animals and plants. According to the laws of biomechanics of the giant dinosaurs could not move and fly. 2. The movement of continents, reliably described by A.Vegener, can only be explained on the basis of the model increasing the Earth. Gravity is only one of the fields that define the existence of the world. Field and matter are forms that can be converted into each other. Transition is described, in particular, by Poincare, perhaps not quite accurate: E = (K) mc2. There are indications of the existence of the time field (Kozyrev, 1978), which generates energy, and then the following conditional equation: T, where T is a time. Through this relationship generated energy glow of stars and planets, the mass increases. In particular, there is an increase in the mass of the Earth. This confirms the divergence of the continents and reducing the size of the animals and plants in the Earth's history. According to presented model, the size of Earth increased during 100 millions years two times in linear scale and 8 times in volume and mass scales. Understanding of general principle of space development needs collaboration of different specialists and branches of geosciences. The basis of possible scheme is: 1. The nature of gravity is not explained by science, although some of its properties are described with high accuracy, and these descriptions have predictive power. Indeed, what attracted threads of the body without physical contact? 2. The velocity of propagation of gravitational forces in the universe is many times the speed of light. Perhaps it is infinite, although it is not proven. 3. The universe is infinite, as is clear from logical calculations thinkers more ancient period. However, our universe, i.e. of the universe, available to our senses and instruments, is finite. The volume of our universe is 1070 cubic kilometers. The total

  7. An Analysis of the Understanding of Geological Time by Students at Secondary and Post-Secondary Level. Research Report

    ERIC Educational Resources Information Center

    Hidalgo, Antonio J.; Otero, Jose

    2004-01-01

    This paper addresses the concept of geological time as used by students who face tasks that demand three types of skills: to locate events in time, to order them according to time calendar, and to manage time intervals. The empirical study consisted of asking high school students as well as technical school students to carry out tasks that…

  8. Timing signatures of large scale solar eruptions

    NASA Astrophysics Data System (ADS)

    Balasubramaniam, K. S.; Hock-Mysliwiec, Rachel; Henry, Timothy; Kirk, Michael S.

    2016-05-01

    We examine the timing signatures of large solar eruptions resulting in flares, CMEs and Solar Energetic Particle events. We probe solar active regions from the chromosphere through the corona, using data from space and ground-based observations, including ISOON, SDO, GONG, and GOES. Our studies include a number of flares and CMEs of mostly the M- and X-strengths as categorized by GOES. We find that the chromospheric signatures of these large eruptions occur 5-30 minutes in advance of coronal high temperature signatures. These timing measurements are then used as inputs to models and reconstruct the eruptive nature of these systems, and explore their utility in forecasts.

  9. Geology and mineral resource assessment of the Venezuelan Guayana Shield at 1:500,000 scale; a digital representation of maps published by the U.S. Geological Survey

    USGS Publications Warehouse

    Schruben, Paul G.; Wynn, J.C.; Gray, Floyd; Cox, D.P.; Sterwart, J.H.; Brooks, W.E.

    1997-01-01

    This CD-ROM contains vector-based digital maps of the geology and resource assessment of the Venezuela Guayana Shield originally published as paper maps in 1993 in U. S. Geological Survey Bulletin 2062, at a scale of 1:1 million and revised in 1993-95 as separate maps at a scale of 1:500,000. Although the maps on this disc can be displayed at different scales, they are not intended to be used at any scale more detailed than 1:500,000.

  10. Boundary|Time|Surface: Art and Geology Meet in Gros Morne National Park, NL, Canada

    NASA Astrophysics Data System (ADS)

    Lancaster, Sydney; Waldron, John

    2015-04-01

    Environmental Art works range in scope from major permanent interventions in the landscape to less intrusive, more ephemeral site-specific installations constructed of materials from the local environment. Despite this range of intervention, however, these works all share in a tradition of art making that situates the artwork in direct response to the surrounding landscape. Andy Goldsworthy and Richard Long, for example, both favour methods that combine elements of both sculpture and performance in the creation of non-permanent interventions in the landscape, and both rely upon photographic, text-based, or video documentation as the only lasting indication of the works' existence. Similarly, Earth Scientists are responsible for interventions in the landscape, both physical and conceptual. For example, in Earth science, the periods of the geologic timescale - Cambrian, Ordovician, Silurian, etc. - were established by 19th century pioneers of geology at a time when they were believed to represent natural chapters in Earth history. Since the mid-20th century, stratigraphers have attempted to resolve ambiguities in the original definitions by defining stratotypes: sections of continuously deposited strata where a single horizon is chosen as a boundary. One such international stratotype, marking the Cambrian-Ordovician boundary, is defined at Green Point in Gros Morne National Park, Newfoundland. Boundary|Time|Surface was an ephemeral sculptural installation work constructed in June 2014. The main installation work was a fence of 52 vertical driftwood poles, 2-3 m tall, positioned precisely along the boundary stratotype horizon at Green Point in Newfoundland. The fence extended across a 150 m wave-cut platform from sea cliffs to the low-water mark, separating Ordovician from Cambrian strata. The installation was constructed by hand (with volunteer assistance) on June 22, as the wave-cut platform was exposed by the falling tide. During the remainder of the tidal cycle

  11. Site characterisation of a basin-scale CO2 geological storage system: Gippsland Basin, southeast Australia

    NASA Astrophysics Data System (ADS)

    Gibson-Poole, C. M.; Svendsen, L.; Underschultz, J.; Watson, M. N.; Ennis-King, J.; van Ruth, P. J.; Nelson, E. J.; Daniel, R. F.; Cinar, Y.

    2008-06-01

    Geological storage of CO2 in the offshore Gippsland Basin, Australia, is being investigated by the Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) as a possible method for storing the very large volumes of CO2 emissions from the nearby Latrobe Valley area. A storage capacity of about 50 million tonnes of CO2 per annum for a 40-year injection period is required, which will necessitate several individual storage sites to be used both sequentially and simultaneously, but timed such that existing hydrocarbon assets will not be compromised. Detailed characterisation focussed on the Kingfish Field area as the first site to be potentially used, in the anticipation that this oil field will be depleted within the period 2015 2025. The potential injection targets are the interbedded sandstones of the Paleocene-Eocene upper Latrobe Group, regionally sealed by the Lakes Entrance Formation. The research identified several features to the offshore Gippsland Basin that make it particularly favourable for CO2 storage. These include: a complex stratigraphic architecture that provides baffles which slow vertical migration and increase residual gas trapping and dissolution; non-reactive reservoir units that have high injectivity; a thin, suitably reactive, lower permeability marginal reservoir just below the regional seal providing mineral trapping; several depleted oil fields that provide storage capacity coupled with a transient production-induced flow regime that enhances containment; and long migration pathways beneath a competent regional seal. This study has shown that the Gippsland Basin has sufficient capacity to store very large volumes of CO2. It may provide a solution to the problem of substantially reducing greenhouse gas emissions from future coal developments in the Latrobe Valley.

  12. The Handling of Hazard Data on a National Scale: A Case Study from the British Geological Survey

    NASA Astrophysics Data System (ADS)

    Royse, Katherine R.

    2011-11-01

    This paper reviews how hazard data and geological map data have been combined by the British Geological Survey (BGS) to produce a set of GIS-based national-scale hazard susceptibility maps for the UK. This work has been carried out over the last 9 years and as such reflects the combined outputs of a large number of researchers at BGS. The paper details the inception of these datasets from the development of the seamless digital geological map in 2001 through to the deterministic 2D hazard models produced today. These datasets currently include landslides, shrink-swell, soluble rocks, compressible and collapsible deposits, groundwater flooding, geological indicators of flooding, radon potential and potentially harmful elements in soil. These models have been created using a combination of expert knowledge (from both within BGS and from outside bodies such as the Health Protection Agency), national databases (which contain data collected over the past 175 years), multi-criteria analysis within geographical information systems and a flexible rule-based approach for each individual geohazard. By using GIS in this way, it has been possible to model the distribution and degree of geohazards across the whole of Britain.

  13. The imprint of climate and geology on the residence times of groundwater

    NASA Astrophysics Data System (ADS)

    Maxwell, Reed M.; Condon, Laura E.; Kollet, Stefan J.; Maher, Kate; Haggerty, Roy; Forrester, Mary Michael

    2016-01-01

    Surface and subsurface flow dynamics govern residence time or water age until discharge, which is a key metric of storage and water availability for human use and ecosystem function. Although observations in small catchments have shown a fractal distribution of ages, residence times are difficult to directly quantify or measure in large basins. Here we use a simulation of major watersheds across North America to compute distributions of residence times. This simulation results in peak ages from 1.5 to 10.5 years, in agreement with isotopic observations from bomb-derived radioisotopes, and a wide range of residence times—from 0.1 to 10,000 years. This simulation suggests that peak residence times are controlled by the mean hydraulic conductivity, a function of the prevailing geology. The shape of the residence time distribution is dependent on aridity, which in turn determines water table depth and the frequency of shorter flow paths. These model results underscore the need for additional studies to characterize water ages in larger systems.

  14. Predicting multi-scale relationships between geomorphology and bedrock geology of the rocky intertidal in Central and Northern California

    NASA Astrophysics Data System (ADS)

    Wheeler, A.; Aiello, I. W.

    2014-12-01

    Substratum geology is fundamental in shaping rocky shore morphology. Specific lithologies have various responses to wave action, tectonic features (e.g. fractures, faults) and sedimentary structures (e.g. bedding), creating distinctive weathering profiles. Along with local oceanography and climate forcing, different rock substrata create coastal morphologies that can vary distinctly between scales, ranging from mm to km. Despite the complexity of the system, qualitative observations show coastal areas with similar rock types share similar geomorphologies. Thus, a statistic relationship between geomorphology (expressed for instance by surface parameter rugosity) and geology can be envisaged. There are multiple benefits of finding such a relationship, as rocky intertidal geomorphology can be an important determinant in which organisms can settle, grow, and survive in near shore communities: allowing the prediction of geomorphologic parameters determining coastal ecology solely based on substratum geology, a crucial aspect in guiding the selection of marine protected areas. This study presents preliminary results of multi-scale geospatial surveys (cm to tens of meters) of rocky intertidal outcrops from Central to Northern California using a Terrestrial Laser Scanner. The outcrops investigated are representative of the most common igneous and sedimentary rocks in California (granitoids, conglomerates, sandstones, mudstones) and metamorphic units. The statistical analysis of the survey data support the hypothesis that surface properties can change significantly with changing scale, each rock type having distinct surface characteristics which are similar to comparable lithologies exposed at different locations. These scale dependent variations are controlled by different lithologic and structural characteristics of the outcrop in question. Our data also suggests lithologic variability within a rock unit could be a very significant factor in controlling changes in

  15. Pennsylvanian time scales and cycle periods

    SciTech Connect

    deV. Klein, G. )

    1990-05-01

    Geochronological results from central Europe indicate that the duration of Pennsylvanian time is only 19 m.y., compared to the Harland et al. and Palmer estimates of 34 m.y. Prior calculations of Pennsylvanian cycle periods from the midcontinent of North America suggesting a fit with Milankovitch orbital parameters may well be in errors; as a consequence, other mechanisms for possible eustatic sea-level changes represented in those cycles are needed. Calculation of cycle periods of 100 ka or less lack precision in stratigraphic intervals representing ages characterized by error margins of millions of years. Thus, cycle periods may be less reliable as an indicator of global process than previously considered, particularly in rocks of Paleozoic and early and middle Mesozoic age.

  16. Effect of the advent and diversification of vascular land plants on mineral weathering through geologic time

    NASA Astrophysics Data System (ADS)

    Knoll, Martin A.; Calvin James, W.

    1987-12-01

    The origin of vascular land plants in the Silurian and their subsequent diversification have had a major effect on mineral weathering through geologic tune. The presence of vascular plants reduces the stability of soil minerals through a net export of ions from soil waters and through the release of complexing organic acids by root mycorrhizae. Additional factors that dictate the nature of plant-induced mineral weathering are (1) the differences in nutrient dynamics between evergreen and deciduous species; (2) the role of specific nutrient sinks (biomass storage and secondary soil mineralization) and outputs (runoff, etc.) in plant ecosystems; and (3) the effect of long- and short-term ecosystem disturbances. First-order increases in overall mineral weathering probably took place in the middle Paleozoic and early Tertiary, following the initial colonization and diversification of land plants and the radiation of deciduous angiospenns. Second-order fluctuations would typify time intervals where paleoecosystem disturbances were maximized, such as periods of climatic instability.

  17. Rapid evaluation of time scale using an optical clock

    NASA Astrophysics Data System (ADS)

    Ido, T.; Hachisu, H.; Nakagawa, F.; Hanado, Y.

    2016-06-01

    Feasibility of steering a time scale using an optical clock is investigated. Since the high stability of optical frequency standards enables rapid evaluation of the scale interval, the requirement for the continuous operation is mitigated. Numerical simulations with the input of real calibration data by a 87Sr lattice clock indicated that the calibrations once in two weeks maintain the time scale within 5 ns level using a currently available hydrogen maser at NICT. “Optical” steering of a time scale by the intermittent calibrations frees an optical frequency standard from being dedicated to the steering, enabling other applications using the same apparatus.

  18. Do quasars evolve over cosmological time scales?

    NASA Astrophysics Data System (ADS)

    Wampler, E. J.; Ponz, D.

    Systematic biases that are redshift dependent can influence the optical discovery of quasars and the evolution laws derived from counts of quasars. New data and their interpretation for quasars brighter than MB = -24 in the Palomar Bright Quasar Survey (BQS) (Schmidt and Green, 1983) are consistent with no evolution. A comparison of BQS quasars with the brightest quasars from the CTIO Schmidt Telescope Survey (Osmer and Smith, 1980) shows that if q(0) is near zero, the comoving density of bright quasars in a Friedmann cosmology is about 15 times higher for the CTIO survey quasars (mean z of about 2.8) than for the BQS quasars (mean z of about 1.8). In this case spectral evolution is also required since the CTIO quasars have stronger CIV 1548 A lines than the BQS quasars of similar luminosity. Alternatively, if q(0) is taken to be near 1, the CTIO survey quasars would then have a lower luminosity than the BQS quasars and these data would be consistent with no evolution. Strong CIV 1548 A lines for the CTIO quasars would then fit the general correlation between absolute quasar luminosity and emission line strength (Wampler, Gaskell, Burke and Baldwin, 1984).

  19. Critical time scale of coarse-graining entropy production

    NASA Astrophysics Data System (ADS)

    Sohn, Jang-il

    2016-04-01

    We study coarse-grained entropy production in an asymmetric random walk system on a periodic one-dimensional lattice. In coarse-grained systems, the original dynamics are unavoidably destroyed, but the coarse-grained entropy production is not hidden below the critical time-scale separation. The hidden entropy production is rapidly increasing near the critical time-scale separation.

  20. Evolutionary time-scale of primate bocaviruses.

    PubMed

    Babkin, Igor V; Tyumentsev, Alexander I; Tikunov, Artem Yu; Kurilshikov, Alexander M; Ryabchikova, Elena I; Zhirakovskaya, Elena V; Netesov, Sergei V; Tikunova, Nina V

    2013-03-01

    Human bocavirus (HBoV) is associated with acute gastroenteritis in humans, occurring mostly in young children and elderly people. Four bocavirus genotypes (HBoV1-HBoV4) have been found so far. Since there were no data on the contribution of HBoV to gastroenteritis in Russia, 1781 fecal samples collected from infants hospitalized with acute gastroenteritis in Novosibirsk, Russia during one year were tested for the presence of nucleic acids from HBoV and three major gastrointestinal viruses (rotavirus A, norovirus II, and astrovirus). HBoV was detected only in 1.9% of the samples: HBoV1 was detected in 0.6% and HBoV2, in 1.3%. Complete genome sequencing of three Novosibirsk isolates was performed. An evolutionary analysis of these sequences and the available sequences of human and great apes bocaviruses demonstrated that the current HBoV genotypes diverged comparatively recently, about 60-300years ago. The independent evolution of bocaviruses from chimpanzees and gorillas commenced at the same time period. This suggests that these isolates of great apes bocaviruses belong to separate genotypes within the species of human bocavirus, which is actually the primate bocavirus. The rate of mutation accumulation in the genome of primate bocaviruses has been estimated as approximately 9×10(-4)substitutions/site/year. It has been demonstrated that HBoV1 diverged from the ancestor common with chimpanzee bocavirus approximately 60-80years ago, while HBoV4 separated from great apes bocaviruses about 200-300years ago. The hypothesis postulating independent evolution of HBoV1 and HBoV4 genotypes from primate bocaviruses has been proposed. PMID:23313830

  1. The Influence of Geologic Heterogeneity on Groundwater Salinity and Aquifer-Ocean Exchange on the Scale of the Continental Shelf

    NASA Astrophysics Data System (ADS)

    Michael, H. A.; Scott, K. C.; Koneshloo, M.; Khan, M. R.; Katie, L.

    2015-12-01

    Exchange of water between aquifers and the ocean critically affects the quality of coastal groundwater resources and modifies ocean chemistry on both short and long timescales. Fresh groundwater has been shown to exist far offshore, and this is a potential future resource. However, controls on the origin of offshore freshened groundwater and the timescale over which it responds to hydrologic change are not well known. Further, high rates of saline groundwater discharge have been observed directly nearshore and with tracers across continental shelves, but the physical explanation for these large fluxes is not well established. Steady-state variable-density groundwater flow and solute transport simulations incorporating geostatistically-generated distributions of aquifer lithology were performed to explore the role of geologic heterogeneity in large-scale coastal groundwater flow and solute transport processes. Results indicate that heterogeneity critically affects both salinity distributions and aquifer-ocean exchange. The position, size, and variability of the mixing zone are influenced by the shore-perpendicular connectivity of the geologic structure. Submarine groundwater discharge extends further offshore and is more highly variable in heterogeneous relative to equivalent homogeneous simulations, and this effect increases with connectivity. The circulation of saline groundwater is consistently higher in heterogeneous simulations relative to homogeneous regardless of aquifer connectivity, increasing up to several orders of magnitude. These simulations suggest that heterogeneous aquifers with high geologic connectivity can result in significant volumes of freshened groundwater accompanied by fresh and saline discharge tens to hundreds of kilometers offshore along the continental shelf, even under present-day equilibrium conditions. The complicated flow fields and salinity distributions resulting from geologic heterogeneity contribute to high rates of saline

  2. Geologic Evolution of Eastern Hellas, Mars: Styles and Timing of Volatile-driven Activity

    NASA Technical Reports Server (NTRS)

    Crown, David A.; Bleamaster, Leslie F., III; Mest, Scott C.

    2004-01-01

    The east rim of the Hellas basin and the surrounding highlands comprise a geologically significant region for evaluating volatile abundance, volatile distribution and cycling, and potential changes in Martian environmental conditions. This region of the Martian surface exhibits landforms shaped by a diversity of geologic processes and has a well-preserved geologic record, with exposures of Noachian, Hesperian, and Amazonian units, as well as spans a wide range in both latitude and elevation due to the magnitude of Hellas basin. In addition, geologically contemporaneous volcanism and volatile-driven activity in the circum-Hellas highlands provide important ingredients for creating habitats for potential Martian life.

  3. Time Scale Creator - A Visualization and Database Tool for Earth History

    NASA Astrophysics Data System (ADS)

    Huang, A.; Ogg, J.

    2008-12-01

    Unravelling Earth's history requires the ability to compare biologic, lithologic, chemical, magnetic and other records from different regions. Published correlation charts provide some details, but tend to be unwieldy, difficult to update, and awkward to merge with other records. The Time Scale Creator program of the International Commission on Stratigraphy provides a suite of global and regional reference datasets (approximately 20,000 Phanerozoic datums, plus geochemical and other trends) within a visualization package. Users can append additional regional lithostratigraphic or other datasets, then create on-screen charts for any portion of the geologic time scale with any subsets of the extensive stratigraphic data. In addition to scalable-vector graphics (SVG) or PDF file output, the on-screen display contains "hot-cursor- points" which open up windows with additional information on events, zones, and URL links to external documentation. For example, a user can select from within a datapack with 50 representative stratigraphic columns spanning the British Isles, then display lithologic sections against models of global sea-level trends or adjacent to Sub-boreal ammonite zones, and the pop-up window for each formation is linked directly to the British Geologic Survey lexicon entry. Much in the way that GIS greatly enhances accessibility to spatial data, the Time Scale Creator and its temporal data are completely digital, allowing quick and easy distribution and updating. The database and visualization package are a convenient reference tool, chart-production device, and educational program.

  4. The Nature of Carbonate and Organic δ13C Covariance Through Geological Time

    NASA Astrophysics Data System (ADS)

    Oehlert, A. M.; Swart, P. K.

    2014-12-01

    Significant evolutionary, climatic, and oceanographic events in Earth history are often accompanied by excursions in the carbon isotope composition (δ13C) of marine carbonates and co-occurring sedimentary organic material. The observation of synchronous excursions in the δ13C values of marine carbonates and coeval organic matter is commonly thought to prove that the deposit has not been altered by diagenesis, and that the variations in the δ13C records are the result of a significant change in global carbon cycling. Furthermore, this model suggests that the covariance of carbonate and organic δ13C records is driven only by changes in the δ13C value of the dissolved inorganic carbon in the surface waters of the ocean. However, recent work suggests that there may be at least two alternate models for generating covariance between carbonate and organic δ13C values in the geologic record. One of the models invokes sea-level driven syndepositional mixing between isotopically distinct sources of carbonate and organic material to produce positive covariance between carbonate and organic δ13C values. The second model suggests that post-depositional alteration to the carbonate δ13C values during meteoric diagenesis, in concert with concurrent contributions of terrestrial organic material during subaerial exposure, can also produce co-occurring negative excursions with tightly covariant δ13C records. In contrast to earlier interpretations of covariant δ13C values, these models suggest that both syndepositional and post-depositional factors can significantly influence the relationship between carbonate and organic δ13C values in a variety of depositional environments. The implications for reconstructions of ancient global carbon cycle events will be explored within the context of these three models, and their relative importance throughout geologic time will be discussed.

  5. Geologically recent small-scale surface features in Meridiani Planum and Gale Crater, Mars

    NASA Astrophysics Data System (ADS)

    Horne, David

    2014-05-01

    Enigmatic small scale (<1m) depositional and erosional features have been imaged at several locations in the equatorial Meridiani Planum region by the rover Opportunity. They occur in loose, dark basaltic sands partly covering exposures of light-toned bedrock. Leveed fissures are narrow, elongate, steep-sided depressions flanked by raised levees or half-cones of soil, typically 2-10 cm wide and up to 50 cm long in most cases. Some cross-cut and are therefore younger than eolian ripples thought to have last been active c. 50,000 years ago. Gutters are elongate, straight or sinuous surface depressions, typically 2-10cm wide and 1-5 cm deep, sometimes internally terraced or with a hollow near one end, and in one case seem to give way to small depositional fans downslope; they have the appearance of having been formed by liquid flow rather than by wind erosion. Leveed fissures were imaged at more than 25 locations by Opportunity between 2004 and 2013, particularly near the rims of Endurance, Erebus and Endeavour craters, but also on the plains between Santa Maria and Endeavour craters; sharply-defined gutters are less common but examples were imaged close to the rim of Endurance and on the approach to Endeavour, whereas subdued, possibly wind-softened examples are more widespread. Scrutiny of images obtained by the rover Spirit in Gusev Crater between 2004 and 2010 has so far failed to find any leveed fissures or gutters, but examples of both types of features, as well as numerous small holes suggestive of surface sediment falling into underlying voids, were imaged by the rover Curiosity in the Yellowknife Bay region of Gale Crater during 2013. Leveed fissures appear to have been formed by venting from beneath. Ground disturbance by the rover can be ruled out in many cases by the appearance of features in images taken before close approach. Blowholes seem plausible close to crater rims (where wind might enter a connected void system through a crater wall) but less so

  6. Scaling analysis of multi-variate intermittent time series

    NASA Astrophysics Data System (ADS)

    Kitt, Robert; Kalda, Jaan

    2005-08-01

    The scaling properties of the time series of asset prices and trading volumes of stock markets are analysed. It is shown that similar to the asset prices, the trading volume data obey multi-scaling length-distribution of low-variability periods. In the case of asset prices, such scaling behaviour can be used for risk forecasts: the probability of observing next day a large price movement is (super-universally) inversely proportional to the length of the ongoing low-variability period. Finally, a method is devised for a multi-factor scaling analysis. We apply the simplest, two-factor model to equity index and trading volume time series.

  7. Frozen in Time? Microbial strategies for survival and carbon metabolism over geologic time in a Pleistocene permafrost chronosequence

    NASA Astrophysics Data System (ADS)

    Mackelprang, R.; Douglas, T. A.; Waldrop, M. P.

    2014-12-01

    Permafrost soils have received tremendous interest due to their importance as a global carbon store with the potential to be thawed over the coming centuries. Instead of being 'frozen in time,' permafrost contains active microbes. Most metagenomic studies have focused on Holocene aged permafrost. Here, we target Pleistocene aged ice and carbon rich permafrost (Yedoma), which can differ in carbon content and stage of decay. Our aim was to understand how microbes in the permafrost transform organic matter over geologic time and to identify physiological and biochemical adaptations that enable long-term survival. We used next-generation sequencing to characterize microbial communities along a permafrost age gradient. Samples were collected from the Cold Regions Research and Engineering Laboratory (CRREL) Permafrost Tunnel near Fox, AK, which penetrates a hillside providing access to permafrost ranging in age from 12 to 40 kyr. DNA was extracted directly from unthawed samples. 16S rRNA amplicon (16S) and shotgun metagenome sequencing revealed significant age-driven differences. First, microbial diversity declines with permafrost age, likely due to long-term exposure to environmental stresses and a reduction in metabolic resources. Second, we observed taxonomic differences among ages, with an increasing abundance of Firmicutes (endospore-formers) in older samples, suggesting that dormancy is a common survival strategy in older permafrost. Ordination of 16S and metagenome data revealed age-based clustering. Genes differing significantly between age categories included those involved in lipopolysaccharide assembly, cold-response, and carbon processing. These data point to the physiological adaptations to long-term frozen conditions and to the metabolic processes utilized in ancient permafrost. In fact, a gene common in older samples is involved in cadaverine production, which could potentially explain the putrefied smell of Pleistocene aged permafrost. Coupled with soil

  8. CO{sub 2} Sequestration Capacity and Associated Aspects of the Most Promising Geologic Formations in the Rocky Mountain Region: Local-Scale Analyses

    SciTech Connect

    Laes, Denise; Eisinger, Chris; Morgan, Craig; Rauzi, Steve; Scholle, Dana; Scott, Phyllis; Lee, Si-Yong; Zaluski, Wade; Esser, Richard; Matthews, Vince; McPherson, Brian

    2013-07-30

    The purpose of this report is to provide a summary of individual local-­scale CCS site characterization studies conducted in Colorado, New Mexico and Utah. These site-­ specific characterization analyses were performed as part of the “Characterization of Most Promising Sequestration Formations in the Rocky Mountain Region” (RMCCS) project. The primary objective of these local-­scale analyses is to provide a basis for regional-­scale characterization efforts within each state. Specifically, limits on time and funding will typically inhibit CCS projects from conducting high-­ resolution characterization of a state-­sized region, but smaller (< 10,000 km{sup 2}) site analyses are usually possible, and such can provide insight regarding limiting factors for the regional-­scale geology. For the RMCCS project, the outcomes of these local-­scale studies provide a starting point for future local-­scale site characterization efforts in the Rocky Mountain region.

  9. Updating the planetary time scale: focus on Mars

    USGS Publications Warehouse

    Tanaka, Kenneth L.; Quantin-Nataf, Cathy

    2013-01-01

    Formal stratigraphic systems have been developed for the surface materials of the Moon, Mars, Mercury, and the Galilean satellite Ganymede. These systems are based on geologic mapping, which establishes relative ages of surfaces delineated by superposition, morphology, impact crater densities, and other relations and features. Referent units selected from the mapping determine time-stratigraphic bases and/or representative materials characteristic of events and periods for definition of chronologic units. Absolute ages of these units in some cases can be estimated using crater size-frequency data. For the Moon, the chronologic units and cratering record are calibrated by radiometric ages measured from samples collected from the lunar surface. Model ages for other cratered planetary surfaces are constructed primarily by estimating cratering rates relative to that of the Moon. Other cratered bodies with estimated surface ages include Venus and the Galilean satellites of Jupiter. New global geologic mapping and crater dating studies of Mars are resulting in more accurate and detailed reconstructions of its geologic history.

  10. Geologically Controlled Isotope-Time Patterns Reveal Early Differentiation and Crust Formation Processes

    NASA Astrophysics Data System (ADS)

    Bennett, V. C.; Nutman, A. P.

    2014-12-01

    The mechanisms of continental crust production and evolution in the early Earth remain controversial, as are questions of the relative roles of early differentiation versus subsequent tectonic procssing in creating Earth's chemical signatures. Here we present geologic observations integrated with whole rock major, trace element and Sm-Nd isotopic signatures and combined with U-Pb and Lu-Hf isotopic compositions of zircon populations from the same rocks, from the most extensive early rock record comprising the 3.9 Ga to 3.6 Ga terranes of southwest Greenland. These data reveal repeated patterns of formation of juvenile TTG crust and associated mafic and ultramafic rocks in convergent margin settings followed by formation of more evolved granites [1]. Our new zircon Lu-Hf data from rare 3.6-3.7 Ga tonalites within the Itsaq Gneiss Complex, obtained from single component, non-migmatitic gneisses with simple zircon populations, limited within sample Hf isotopic variability and accurate U-Pb ages, now document extraction of juvenile tonalites from a near chondritic mantle source between 3.9 Ga and 3.6 Ga. The more evolved, granitic rocks in each area show slightly negative initial ɛHf in accord with crustal reworking of the older (3.8-3.9 Ga) gniesses. There is no evidence for Hadean material in the sources of the granitoids. The Hf isotope-time patterns are consistent with juvenile crust production from a mantle source that experienced only modest amounts of prior crustal extraction. They are distinct from those predicted by reprocessing of an enriched Hadean mafic crust, as has been proposed for this region [2] and for the source of the Hadean Jack Hills zircons [3]. The well-documented, time decreasing, positive 142Nd anomalies [e.g., 4] from these rocks are further evidence of crustal derivation from a convecting mantle source, rather than reworking of an enriched mafic lithosphere. The 143Nd isotopic -time patterns are more complex, reflecting the interplay

  11. On time scale invariance of random walks in confined space.

    PubMed

    Bearup, Daniel; Petrovskii, Sergei

    2015-02-21

    Animal movement is often modelled on an individual level using simulated random walks. In such applications it is preferable that the properties of these random walks remain consistent when the choice of time is changed (time scale invariance). While this property is well understood in unbounded space, it has not been studied in detail for random walks in a confined domain. In this work we undertake an investigation of time scale invariance of the drift and diffusion rates of Brownian random walks subject to one of four simple boundary conditions. We find that time scale invariance is lost when the boundary condition is non-conservative, that is when movement (or individuals) is discarded due to boundary encounters. Where possible analytical results are used to describe the limits of the time scaling process, numerical results are then used to characterise the intermediate behaviour. PMID:25481837

  12. Liquidity Spillover in International Stock Markets through Distinct Time Scales

    PubMed Central

    Righi, Marcelo Brutti; Vieira, Kelmara Mendes

    2014-01-01

    This paper identifies liquidity spillovers through different time scales based on a wavelet multiscaling method. We decompose daily data from U.S., British, Brazilian and Hong Kong stock markets indices in order to calculate the scale correlation between their illiquidities. The sample is divided in order to consider non-crisis, sub-prime crisis and Eurozone crisis. We find that there are changes in correlations of distinct scales and different periods. Association in finest scales is smaller than in coarse scales. There is a rise on associations in periods of crisis. In frequencies, there is predominance for significant distinctions involving the coarsest scale, while for crises periods there is predominance for distinctions on the finest scale. PMID:24465918

  13. Liquidity spillover in international stock markets through distinct time scales.

    PubMed

    Righi, Marcelo Brutti; Vieira, Kelmara Mendes

    2014-01-01

    This paper identifies liquidity spillovers through different time scales based on a wavelet multiscaling method. We decompose daily data from U.S., British, Brazilian and Hong Kong stock markets indices in order to calculate the scale correlation between their illiquidities. The sample is divided in order to consider non-crisis, sub-prime crisis and Eurozone crisis. We find that there are changes in correlations of distinct scales and different periods. Association in finest scales is smaller than in coarse scales. There is a rise on associations in periods of crisis. In frequencies, there is predominance for significant distinctions involving the coarsest scale, while for crises periods there is predominance for distinctions on the finest scale. PMID:24465918

  14. Space and Time Scale Variability and Interdependencies in Hydrological Processes

    NASA Astrophysics Data System (ADS)

    Feddes, Reinder A.

    1995-09-01

    The atmospheric, hydrologic, and terrestrial components of the earth's systems operate on different time and space scales. Resolving these scaling incongruities as well as understanding and modeling the complex interaction of land surface processes at the different scales represents a major challenge for hydrologists, ecologists and meteorologists alike. This book presents the contributions of hydrologists, meteorologists, and ecologists to the first IHP/IAHS George Kovacs Colloqium on global hydrology and climate change. It deals with time and space scale variations with reference to several topics including soil water balance, ecosystems and interaction of flow systems, and macroscale hydrologic modeling. This book will be of great use to researchers, engineers and forecasters with an interest in space and time scale variability.

  15. Coupled Evolution of the Martian Atmosphere and Crust Through Geologic Time

    NASA Astrophysics Data System (ADS)

    Hutchins, Kevin Sean

    1998-09-01

    This dissertation investigates the coupled evolution of the Martian atmosphere and crust throughout geologic time and the implications for Martian sample analysis and exobiology. Abundant geological and atmospheric evidence suggests that Mars has changed significantly throughout time. Removal of volatiles from the atmosphere may have been the trigger for the dramatic transition from that scenario to the present cold, harsh climate. Previous modeling work has shown that loss to space enriches the residual atmosphere in the heavier isotopes. Furthermore, stable isotope measurements from secondary mineral deposits within the Martian meteorites indicate exchange with an isotopically-enriched atmosphere. To investigate the Martian climate history, we developed an atmospheric evolution model for argon and neon considering a mass balance between the mantle, atmosphere, and loss to space by sputtering. Sputtering loss is particularly relevant for noble gases which have few mechanisms of escape. Due to substantial loss, our model is only capable of explaining <25% and <2.5% of the atmospheric abundance of argon and neon, respectively. Thus, sources of volatiles are required in addition to volcanic outgassing. We examined the impact of a Martian paleomagnetic field on sputtering loss. A strong magnetic field could limit sputtering loss by deflecting the solar wind around the upper atmosphere. We found that a magnetic field that persists until 1-2 Ga could affect the loss of light noble gases from the atmosphere. Nonetheless, our model predicts additional sources to balance the atmospheric volatile budgets. Therefore, we investigated outgassing from the Martian crust via groundwater circulation. We found that a crustal reservoir 5-25 km thick could satisfy the atmospheric argon budget. Recently, putative evidence of life has been purported for the Martian meteorite ALH84001. We examined the stable isotope measurements from carbonate and organic deposits found in ALH84001. Due

  16. Physical geology

    SciTech Connect

    Skinner, B.; Porter, S.

    1987-01-01

    The book integrates current thinking on processes (plate techtonics, chemical cycles, changes throughout geologic time). It is an introduction to investigations into the way the earth works, how mountains are formed, how the atmosphere, hydrosphere, crust and mantle interact with each other. Treatments on climate, paleoclimatology and landscape evolution are included, as is a discussion on how human activity affects geological interactions.

  17. Regional and Site-Scale Hydrogeologic Analyses of a Proposed Canadian Deep Geologic Repository for Low and Intermediate Level Radioactive Waste

    NASA Astrophysics Data System (ADS)

    Sykes, J. F.; Normani, S. D.; Yin, Y.; Sykes, E. A.

    2009-05-01

    analyses can be computationally intensive, particularly for large-scale dynamic problems that couple energy, flow and mass transport. Important in the sensitivity analysis is the selection of the performance measure used to evaluate the system. The traditional metric of average water particle travel time is inappropriate for geologic units such as the Ordovician and lower Silurian where solute transport is diffusion dominant. The use of life expectancy and groundwater age is a more appropriate metric for such a system. The mean life expectancy for the DGR and base-case parameters has been estimated to be in excess of 8 million years. The analyses support the conclusion that solute transport in the Ordovician sediments is diffusion dominant.

  18. NEA Scout Solar Sail: Half-scale Fold Time Lapse

    NASA Video Gallery

    In this time lapse, the Near-Earth Asteroid Scout (NEA Scout) CubeSat team rolls a half-scale prototype of the small satellite's solar sail in preparation for a deployment test. During its mission,...

  19. Time-windows-based filtering method for near-surface detection of leakage from geologic carbon sequestration sites

    SciTech Connect

    Pan, L.; Lewicki, J.L.; Oldenburg, C.M.; Fischer, M.L.

    2010-02-28

    We use process-based modeling techniques to characterize the temporal features of natural biologically controlled surface CO{sub 2} fluxes and the relationships between the assimilation and respiration fluxes. Based on these analyses, we develop a signal-enhancing technique that combines a novel time-window splitting scheme, a simple median filtering, and an appropriate scaling method to detect potential signals of leakage of CO{sub 2} from geologic carbon sequestration sites from within datasets of net near-surface CO{sub 2} flux measurements. The technique can be directly applied to measured data and does not require subjective gap filling or data-smoothing preprocessing. Preliminary application of the new method to flux measurements from a CO{sub 2} shallow-release experiment appears promising for detecting a leakage signal relative to background variability. The leakage index of ?2 was found to span the range of biological variability for various ecosystems as determined by observing CO{sub 2} flux data at various control sites for a number of years.

  20. Kibble-Zurek mechanism and finite-time scaling

    NASA Astrophysics Data System (ADS)

    Huang, Yingyi; Yin, Shuai; Feng, Baoquan; Zhong, Fan

    2014-10-01

    The Kibble-Zurek (KZ) mechanism has been applied to a variety of systems ranging from low-temperature Bose-Einstein condensations to grand unification scales in particle physics and cosmology and from classical phase transitions to quantum phase transitions. Here, we show that finite-time scaling (FTS) provides a detailed improved understanding of the mechanism. In particular, the finite time scale, which is introduced by the external driving (or quenching) and results in FTS, is the origin of the division of the adiabatic regimes from the impulse regime in the KZ mechanism. The origin of the KZ scaling for the defect density, generated during the driving through a critical point, is not that the correlation length ceases growing in the nonadiabatic impulse regime, but rather, is that it is taken over by the effective finite length scale corresponding to the finite time scale. We also show that FTS accounts well for and improves the scaling ansatz proposed recently by Liu, Polkovnikov, and Sandvik, [Phys. Rev. B 89, 054307 (2014), 10.1103/PhysRevB.89.054307]. Further, we show that their universal power-law scaling form applies only to some observables in cooling but not to heating. Even in cooling, it is invalid either when an appropriate external field is present. However, this finite-time-finite-size scaling calls for caution in application of FTS. Detailed scaling behaviors of the FTS and finite-size scaling, along with their crossover, are explicitly demonstrated, with the dynamic critical exponent z being estimated for two- and three-dimensional Ising models under the usual Metropolis dynamics. These values of z are found to give rise to better data collapses than the extant values do in most cases but take on different values in heating and cooling in both two- and three-dimensional spaces.

  1. Diffusion Time-Scale of Porous Pressure-Sensitive Paint

    NASA Technical Reports Server (NTRS)

    Liu, Tianshu; Teduka, Norikazu; Kameda, Masaharu; Asai, Keisuke

    2001-01-01

    Pressure-sensitive paint (PSP) is an optical pressure sensor that utilizes the oxygen quenching of luminescence. PSP measurements in unsteady aerodynamic flows require fast time response of the paint. There are two characteristic time-scales that are related to the time response of PSP. One is the luminescent lifetime representing an intrinsic physical limit for the achievable temporal resolution of PSP. Another is the time-scale of oxygen diffusion across the PSP layer. When the time-scale of oxygen diffusion is much larger than the luminescent lifetime, the time response of PSP is controlled by oxygen diffusion. In a thin homogenous polymer layer where diffusion is Fickian, the oxygen concentration 1021 can be described by the diffusion equation in one-dimension.

  2. Time scale of riverine sediment transfer in East Asia: from source to sink

    NASA Astrophysics Data System (ADS)

    Li, Chao; Yang, Shouye; Zhao, Jianxin; Bi, Lei

    2015-04-01

    River on the earth surface is like the blood vessel for human body, which transports huge nutrients from the vast continent to the deep ocean. The knowledge of the river transit process leads to better understanding of the continent weathering and earth surface evolution. However, this process, particularly its timescale, is rarely studied due to the poor geological tracer. In this regard, our work aims to reconstruct the sediment transport time in Changjiang (Yangtze River) and Taiwan rivers by mean of "Comminution Age" based on 234U/238U in the lithogenic fraction. As the largest river in Asia, Changjiang is characterized by "Large river/delta + wide shelf + huge input + slower sediment transfer + strong anthropogenic impact", while the Taiwan rivers are featured for "Mountainous river + narrow shelf + huge and rapid sediment transfer + extreme climate event". The distinct geological and topographical features in both river systems result in different sediment "source to sink" processes in terms of time scale. Our calculation shows that the sediment transport time, which is largely depended on basin topography and its weathering condition, in Changjiang basin is much longer (400 ky) than that in Taiwan river basin (120 ky). This work provides the first quantitative constraint on time scale of sediment source to sink process in East Asia, which probably sheds a new insight into weathering regime and sediment recycling in East Asia and northwest Pacific. Acknowledgments This work was supported by the Foundation of Key Laboratory of Yangtze River Water Environment (YRWEF201305), Key Laboratory of Marine Hydrocarbon Resources and Environmental Geology (MRE201402) and the Natural Science Foundation of China (41306040; 41225020).

  3. Time scale for point-defect equilibration in nanostructures

    SciTech Connect

    Millett, Paul C.; Wolf, Dieter; Desai, Tapan; Yamakov, Vesselin

    2008-10-20

    Molecular dynamics simulations of high-temperature annealing are performed on nanostructured materials enabling direct observation of vacancy emission from planar defects (i.e., grain boundaries and free surfaces) to populate the initially vacancy-free grain interiors on a subnanosecond time scale. We demonstrate a universal time-length scale correlation that governs these re-equilibration processes, suggesting that nanostructures are particularly stable against perturbations in their point-defect concentrations, caused for example by particle irradiation or temperature fluctuations.

  4. Unification of Small and Large Time Scales for Biological Evolution: Deviations from Power Law

    NASA Astrophysics Data System (ADS)

    Chowdhury, Debashish; Stauffer, Dietrich; Kunwar, Ambarish

    2003-02-01

    We develop a unified model that describes both “micro” and “macro” evolutions within a single theoretical framework. The ecosystem is described as a dynamic network; the population dynamics at each node of this network describes the “microevolution” over ecological time scales (i.e., birth, ageing, and natural death of individual organisms), while the appearance of new nodes, the slow changes of the links, and the disappearance of existing nodes accounts for the “macroevolution” over geological time scales (i.e., the origination, evolution, and extinction of species). In contrast to several earlier claims in the literature, we observe strong deviations from power law in the regime of long lifetimes.

  5. Global sedimentary geology program

    SciTech Connect

    Ginsburg, R.N.; Clifton, H.E.; Weimer, R.J.

    1986-07-01

    The Society of Economic Paleontologists and Mineralogists, in collaboration with the International Association of Sedimentologists and the International Union of Geological Sciences Committee on Sedimentology, is developing a new international study under the provisional title of Global Sedimentary Geology Program (GSGP). Initially, three research themes are being considered: (1) event stratigraphy-the documentation of examples of mass extinctions, eustatic fluctuations in sea level, major episodes of volcanisms, and changes in ocean composition; (2) facies models in time and space-an expansion of the existing data base of examples of facies models (e.G., deltas, fluvial deposits, and submarine fans) and global-scale study of the persistence of facies at various times in geologic history; and (3) sedimentary indices of paleogeography and tectonics-the use of depositional facies and faunas in paleogeography and in assessing the timing, locus, and characteristics of tectonism. Plans are being developed to organize pilot projects in each of these themes.

  6. Scale-dependent intrinsic entropies of complex time series.

    PubMed

    Yeh, Jia-Rong; Peng, Chung-Kang; Huang, Norden E

    2016-04-13

    Multi-scale entropy (MSE) was developed as a measure of complexity for complex time series, and it has been applied widely in recent years. The MSE algorithm is based on the assumption that biological systems possess the ability to adapt and function in an ever-changing environment, and these systems need to operate across multiple temporal and spatial scales, such that their complexity is also multi-scale and hierarchical. Here, we present a systematic approach to apply the empirical mode decomposition algorithm, which can detrend time series on various time scales, prior to analysing a signal's complexity by measuring the irregularity of its dynamics on multiple time scales. Simulated time series of fractal Gaussian noise and human heartbeat time series were used to study the performance of this new approach. We show that our method can successfully quantify the fractal properties of the simulated time series and can accurately distinguish modulations in human heartbeat time series in health and disease. PMID:26953181

  7. Russian national time scale long-term stability

    NASA Technical Reports Server (NTRS)

    Alshina, A. P.; Gaigerov, B. A.; Koshelyaevsky, N. B.; Pushkin, S. B.

    1994-01-01

    The Institute of Metrology for Time and Space NPO 'VNIIFTRI' generates the National Time Scale (NTS) of Russia -- one of the most stable time scales in the world. Its striking feature is that it is based on a free ensemble of H-masers only. During last two years the estimations of NTS longterm stability based only on H-maser intercomparison data gives a flicker floor of about (2 to 3) x 10(exp -15) for averaging times from 1 day to 1 month. Perhaps the most significant feature for a time laboratory is an extremely low possible frequency drift -- it is too difficult to estimate it reliably. The other estimations, free from possible inside the ensemble correlation phenomena, are available based on the time comparison of NTS relative to the stable enough time scale of outer laboratories. The data on NTS comparison relative to the time scale of secondary time and frequency standards at Golitzino and Irkutsk in Russia and relative to NIST, PTB and USNO using GLONASS and GPS time transfer links gives stability estimations which are close to that based on H-maser intercomparisons.

  8. Trends in Surface Radiation Budgets at Climatic Time Scales

    NASA Astrophysics Data System (ADS)

    Pinker, R. T.; Zhang, B.; Ma, Y.

    2015-12-01

    For assessment of variability and trends in the Earth Radiation Balance, information is needed at climatic time scales. Satellite observations have been instrumental for advancing the understanding of radiative balance at global scale, however, the length of available satellite records is limited due to the frequent changes in the observing systems. In this paper we report on an effort to synthesize satellite observations from independent sources to estimates shortwave and longwave surface radiative fluxes at climatic time scales and use them to learn about their variability and trends at global scale with a focus on the tropics. An attempt will be made to learn from the comparison about possible causes of observed trends. The radiative fluxes were derived in the framework of the MEaSURES and NEWS programs; they are evaluated against ground observations and compared to independent satellite and model estimates. Attention is given to updated knowledge on radiative balance as compared to what is known from shorter time records.

  9. Authigenic iron oxide proxies for marine zinc over geological time and implications for eukaryotic metallome evolution.

    PubMed

    Robbins, L J; Lalonde, S V; Saito, M A; Planavsky, N J; Mloszewska, A M; Pecoits, E; Scott, C; Dupont, C L; Kappler, A; Konhauser, K O

    2013-07-01

    Here, we explore enrichments in paleomarine Zn as recorded by authigenic iron oxides including Precambrian iron formations, ironstones, and Phanerozoic hydrothermal exhalites. This compilation of new and literature-based iron formation analyses track dissolved Zn abundances and constrain the magnitude of the marine reservoir over geological time. Overall, the iron formation record is characterized by a fairly static range in Zn/Fe ratios throughout the Precambrian, consistent with the shale record (Scott et al., 2013, Nature Geoscience, 6, 125-128). When hypothetical partitioning scenarios are applied to this record, paleomarine Zn concentrations within about an order of magnitude of modern are indicated. We couple this examination with new chemical speciation models to interpret the iron formation record. We present two scenarios: first, under all but the most sulfidic conditions and with Zn-binding organic ligand concentrations similar to modern oceans, the amount of bioavailable Zn remained relatively unchanged through time. Late proliferation of Zn in eukaryotic metallomes has previously been linked to marine Zn biolimitation, but under this scenario the expansion in eukaryotic Zn metallomes may be better linked to biologically intrinsic evolutionary factors. In this case, zinc's geochemical and biological evolution may be decoupled and viewed as a function of increasing need for genome regulation and diversification of Zn-binding transcription factors. In the second scenario, we consider Archean organic ligand complexation in such excess that it may render Zn bioavailability low. However, this is dependent on Zn-organic ligand complexes not being bioavailable, which remains unclear. In this case, although bioavailability may be low, sphalerite precipitation is prevented, thereby maintaining a constant Zn inventory throughout both ferruginous and euxinic conditions. These results provide new perspectives and constraints on potential couplings between the

  10. The relationship of angiosperms and oleanane in petroleum through geologic time

    SciTech Connect

    Moldowan, J.M.; Dahl, J.E.; Huizinga, B.J.; Jacobson, S.R.; Taylor, D.W.

    1993-02-01

    The biological marker oleanane has been suggested as an indicator of angiosperm (flowering plant) input into source rocks and their derived oils. Parallels should therefore be evident between the angiosperm fossil record and oleanane occurrence and abundance. A global selection of more than 50 core samples from marine rocks of different ages and from different locations was quantitatively analyzed for oleanane to determine its abundance over geologic time relative to the bacterial marker hopane. Oleanane was recognized using Metastable Reaction Monitoring (MRM) GC-MS. A parallel was observed between the oleanane/hopane ratio and angiosperm diversity in the fossil record through time. The first fossil evidence of angiosperms is during the Early Cretaceous with radiation during the Late Cretaceous and Tertiary. Occurrences of oleanane are confirmed throughout the Cretaceous system. Early-to-middle Cretaceous (Berriasian-Cenomanian) occurrences are sporadic and oleanan/hopane ratios are less than 0.07. Late Cretaceous (Turonian-Maastrichtian) oleanane/hopane ratios range up to 0.15 with higher ratios in many Tertiary samples. It appears that oleanane/hopane ratios of oils can restrict the age of their unavailable or unknown source rocks. High ratios indicate Tertiary age and lower ratios can indicate Cretaceous or Tertiary age, depending on depositional environment. While these data do not rule out pre-Cretaceous oleanane, preliminary data show that oleanane/hopane ratios for Jurassic and older rock extracts are typically below our detection limits (<0.03). While oleanane precursors are abundant in angiosperms, they also occur, rarely, in other modern plant groups. We identified oleanane in low abundances in three Early Cretaceous fossil benettitialeans, an extinct plant group (Late Triassic to Late Cretaceous) thought to be related to angiosperms. These findings suggest that oleanane could be present in low abundance in some pre-Cretaceous rocks and oils.

  11. Heterogeneity and Scaling in Geologic Media: Applications to Transport in the Vadose and Saturated Zones

    SciTech Connect

    Stephen R. Brown; Gregory Boitnott; Gilles Y. Bussod; Paul Hagin

    2005-12-13

    In building models of the subsurface, it is generally acknowledged that the required properties are rarely known or observed at the scale of the model elements. Typically they are constrained by measurements or observations made at other scales such as smaller scale core measurements or larger scale wellbore or field tests. As a result, model parameters contain a certain level of uncertainty even in the best of cases. These values typically require adjustment to fit field observations through a process commonly referred to as calibration. The characterization of flow and transport in the vadose and saturated zones, requires a detailed knowledge of subsurface structures, flow paths, and hydrophysical properties. We have constructed a methodology and workflow that use fine-scale measurements of heterogeneity to constrain physically based models for upscaling geophysical and hydrological properties. The methodology provides a means to assign hydrophysical properties at scales more appropriate to field applications, while preserving a physical influence of fine scale heterogeneities. We start by describing millimeter-scale physical properties measurements made on the surface of a sample. Combining physical properties maps and measured parameters with effective medium models, we show that these fine-scale heterogeneities can cause saturation dependent anisotropy in several properties such as electrical conductivity, relative permeability and velocity. Finally, we demonstrate that traditional upscaling of multiphase properties such as capillary pressure leads to inaccuracies that can be avoided by employing upscaling that explicitly incorporates fine-scale heterogeneity. This methodology provides a more accurate interpretation and representation of the subsurface for both environmental and fossil fuel reservoir applications, and can be extended to the study of surface damage in man made structures such as concrete. Realistic hydrologic, geophysical and hydrochemical

  12. Multiple-time scales analysis of physiological time series under neural control

    NASA Technical Reports Server (NTRS)

    Peng, C. K.; Hausdorff, J. M.; Havlin, S.; Mietus, J. E.; Stanley, H. E.; Goldberger, A. L.

    1998-01-01

    We discuss multiple-time scale properties of neurophysiological control mechanisms, using heart rate and gait regulation as model systems. We find that scaling exponents can be used as prognostic indicators. Furthermore, detection of more subtle degradation of scaling properties may provide a novel early warning system in subjects with a variety of pathologies including those at high risk of sudden death.

  13. The Average Density of Extrasolar Habitable Planets Over Cosmological Time Scales

    NASA Astrophysics Data System (ADS)

    von Bloh, W.; Franck, S.; Bounama, C.; Schellnhuber, H. J.

    A general modelling scheme for assessing the suitability for life on any Earth-like ex- trasolar planet is presented. This approach is based on an integrated Earth system anal- ysis in order to calculate the habitable zone in main-sequence-star planetary systems. Within this model the evolution of the habitable zone over geological time scales is straightforward to calculate and allows an estimate of the probability that an Earth-like planet is within the habitable zone of an extrasolar planetary system. The probability depends explicitly on the time since planet formation. A new attempt by Lineweaver (2001) to estimate the formation rate of Earth-like planets over cosmological time scales is applied to calculate the average density of habitable planets as a function of time. This approach is based on a quantitative determination of metallicity from star formation rates as an ingredient for forming Earth-like planets. Combining this result with our estimations of extrasolar habitable zones yields the average density of habit- able planets over cosmological time scales. We find that there was a maximum density of habitable planets at the time of Earth's origin.

  14. The time scale of the silicate weathering negative feedback on atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Colbourn, G.; Ridgwell, A.; Lenton, T. M.

    2015-05-01

    The ultimate fate of CO2 added to the ocean-atmosphere system is chemical reaction with silicate minerals and burial as marine carbonates. The time scale of this silicate weathering negative feedback on atmospheric pCO2 will determine the duration of perturbations to the carbon cycle, be they geological release events or the current anthropogenic perturbation. However, there has been little previous work on quantifying the time scale of the silicate weathering feedback, with the primary estimate of 300-400 kyr being traceable to an early box model study by Sundquist (1991). Here we employ a representation of terrestrial rock weathering in conjunction with the "GENIE" (Grid ENabled Integrated Earth system) model to elucidate the different time scales of atmospheric CO2 regulation while including the main climate feedbacks on CO2 uptake by the ocean. In this coupled model, the main dependencies of weathering—runoff, temperature, and biological productivity—were driven from an energy-moisture balance atmosphere model and parameterized plant productivity. Long-term projections (1 Myr) were conducted for idealized scenarios of 1000 and 5000 PgC fossil fuel emissions and their sensitivity to different model parameters was tested. By fitting model output to a series of exponentials we determined the e-folding time scale for atmospheric CO2 drawdown by silicate weathering to be ˜240 kyr (range 170-380 kyr), significantly less than existing quantifications. Although the time scales for reequilibration of global surface temperature and surface ocean pH are similar to that for CO2, a much greater proportion of the peak temperature anomaly persists on this longest time scale; ˜21% compared to ˜10% for CO2.

  15. Scaling properties in time-varying networks with memory

    NASA Astrophysics Data System (ADS)

    Kim, Hyewon; Ha, Meesoon; Jeong, Hawoong

    2015-12-01

    The formation of network structure is mainly influenced by an individual node's activity and its memory, where activity can usually be interpreted as the individual inherent property and memory can be represented by the interaction strength between nodes. In our study, we define the activity through the appearance pattern in the time-aggregated network representation, and quantify the memory through the contact pattern of empirical temporal networks. To address the role of activity and memory in epidemics on time-varying networks, we propose temporal-pattern coarsening of activity-driven growing networks with memory. In particular, we focus on the relation between time-scale coarsening and spreading dynamics in the context of dynamic scaling and finite-size scaling. Finally, we discuss the universality issue of spreading dynamics on time-varying networks for various memory-causality tests.

  16. Thermodynamics Constrains Allometric Scaling of Optimal Development Time in Insects

    PubMed Central

    Dillon, Michael E.; Frazier, Melanie R.

    2013-01-01

    Development time is a critical life-history trait that has profound effects on organism fitness and on population growth rates. For ectotherms, development time is strongly influenced by temperature and is predicted to scale with body mass to the quarter power based on 1) the ontogenetic growth model of the metabolic theory of ecology which describes a bioenergetic balance between tissue maintenance and growth given the scaling relationship between metabolism and body size, and 2) numerous studies, primarily of vertebrate endotherms, that largely support this prediction. However, few studies have investigated the allometry of development time among invertebrates, including insects. Abundant data on development of diverse insects provides an ideal opportunity to better understand the scaling of development time in this ecologically and economically important group. Insects develop more quickly at warmer temperatures until reaching a minimum development time at some optimal temperature, after which development slows. We evaluated the allometry of insect development time by compiling estimates of minimum development time and optimal developmental temperature for 361 insect species from 16 orders with body mass varying over nearly 6 orders of magnitude. Allometric scaling exponents varied with the statistical approach: standardized major axis regression supported the predicted quarter-power scaling relationship, but ordinary and phylogenetic generalized least squares did not. Regardless of the statistical approach, body size alone explained less than 28% of the variation in development time. Models that also included optimal temperature explained over 50% of the variation in development time. Warm-adapted insects developed more quickly, regardless of body size, supporting the “hotter is better” hypothesis that posits that ectotherms have a limited ability to evolutionarily compensate for the depressing effects of low temperatures on rates of biological processes

  17. Variability in 14C contents of soil organic matter at the plot and regional scale across climatic and geologic gradients

    NASA Astrophysics Data System (ADS)

    van der Voort, Tessa Sophia; Hagedorn, Frank; McIntyre, Cameron; Zell, Claudia; Walthert, Lorenz; Schleppi, Patrick; Feng, Xiaojuan; Eglinton, Timothy Ian

    2016-06-01

    Soil organic matter (SOM) forms the largest terrestrial pool of carbon outside of sedimentary rocks. Radiocarbon is a powerful tool for assessing soil organic matter dynamics. However, due to the nature of the measurement, extensive 14C studies of soil systems remain relatively rare. In particular, information on the extent of spatial and temporal variability in 14C contents of soils is limited, yet this information is crucial for establishing the range of baseline properties and for detecting potential modifications to the SOM pool. This study describes a comprehensive approach to explore heterogeneity in bulk SOM 14C in Swiss forest soils that encompass diverse landscapes and climates. We examine spatial variability in soil organic carbon (SOC) 14C, SOC content and C : N ratios over both regional climatic and geologic gradients, on the watershed- and plot-scale and within soil profiles. Results reveal (1) a relatively uniform radiocarbon signal across climatic and geologic gradients in Swiss forest topsoils (0-5 cm, Δ14C = 130 ± 28.6, n = 12 sites), (2) similar radiocarbon trends with soil depth despite dissimilar environmental conditions, and (3) micro-topography dependent, plot-scale variability that is similar in magnitude to regional-scale variability (e.g., Gleysol, 0-5 cm, Δ14C 126 ± 35.2, n = 8 adjacent plots of 10 × 10 m). Statistical analyses have additionally shown that Δ14C signature in the topsoil is not significantly correlated to climatic parameters (precipitation, elevation, primary production) except mean annual temperature at 0-5 cm. These observations have important consequences for SOM carbon stability modelling assumptions, as well as for the understanding of controls on past and current soil carbon dynamics.

  18. Analysis of College Students' Ideas about Geologic Time: Questionnaires and Interviews From Four Institutions

    NASA Astrophysics Data System (ADS)

    Anderson, S. W.; Libarkin, J. C.; Beilfuss, M.; Dahl, J.; Boone, W. J.

    2002-05-01

    Approximately 300 questionnaires and 50 interviews were conducted with introductory and non-science major college students from four institutions: a small elite private school, two large state schools, and one small public liberal arts college. Students were probed on a variety of topics about the Earth system, including geologic time. A number of widely held preconceptions were uncovered on all four campuses, although scientific ideas appeared with greater frequency at the single private institution. Predominate non-scientific preconceptions included: 1) "Instantaneous" creation, wherein the Earth is formed with a modern-day surface appearance, although not necessarily including life. This idea is traced to religious ideas in about half of the cases. 2) Life existed when the Earth first formed. Approximately 40-70 percent of public students and 30 percent of private students believed life existed "when the Earth was formed". This life takes a variety of forms, including simple or single-celled life, water-born life, and life essentially identical to modern. 3) Experiential preconceptions. A variety of ideas possibly garnered from books, secondary school curriculum, film, and TV were prevalent. For instance, a number of ideas about the appearance of the Earth at formation are derivative of scientific ideas, such as the idea that a supercontinent (Pangea) existed, the Earth as covered with water or ice, and that algae were present at Earth's formation. Student interviews also revealed difficulty in extrapolating scientific concepts into a future context. For example, several students correctly showed the movement of continents from the past to present, but showed no change in position when queried about the appearance of the Earth's surface well into the future.

  19. Deviations from uniform power law scaling in nonstationary time series

    NASA Technical Reports Server (NTRS)

    Viswanathan, G. M.; Peng, C. K.; Stanley, H. E.; Goldberger, A. L.

    1997-01-01

    A classic problem in physics is the analysis of highly nonstationary time series that typically exhibit long-range correlations. Here we test the hypothesis that the scaling properties of the dynamics of healthy physiological systems are more stable than those of pathological systems by studying beat-to-beat fluctuations in the human heart rate. We develop techniques based on the Fano factor and Allan factor functions, as well as on detrended fluctuation analysis, for quantifying deviations from uniform power-law scaling in nonstationary time series. By analyzing extremely long data sets of up to N = 10(5) beats for 11 healthy subjects, we find that the fluctuations in the heart rate scale approximately uniformly over several temporal orders of magnitude. By contrast, we find that in data sets of comparable length for 14 subjects with heart disease, the fluctuations grow erratically, indicating a loss of scaling stability.

  20. Soils and Global Change in the Carbon Cycle over Geological Time

    NASA Astrophysics Data System (ADS)

    Retallack, G. J.

    2003-12-01

    sedimentary rocks; organic matter burial is an important long-term control on CO2 levels in the atmosphere (Berner and Kothavala, 2001). The magnitudes of carbon pools and fluxes involved provide a perspective on the importance of soils compared with other carbon reservoirs ( Figure 1). (6K)Figure 1. Pools and fluxes of reduced carbon (bold) and oxidized carbon (regular) in Gt in the pre-industrial carbon cycle (sources Schidlowski and Aharon, 1992; Siegenthaler and Sarmiento, 1993; Stallard, 1998). Before industrialization, there was only 600 Gt (1 Gt=1015g) of carbon in CO2 and methane in the atmosphere, which is about the same amount as in all terrestrial biomass, but less than half of the reservoir of soil organic carbon. The ocean contained only ˜3 Gt of biomass carbon. The deep ocean and sediments comprised the largest reservoir of bicarbonate and organic matter, but that carbon has been kept out of circulation from the atmosphere for geologically significant periods of time (Schidlowski and Aharon, 1992). Humans have tapped underground reservoirs of fossil fuels, and our other perturbations of the carbon cycle have also been significant ( Vitousek et al., 1997b; see Chapter 8.10).Atmospheric increase of carbon in CO2 to 750 Gt C by deforestation and fossil fuel burning has driven ongoing global warming, but is not quite balanced by changes in the other carbon reservoirs leading to search for a "missing sink" of some 1.8±1.3 GtC, probably in terrestrial organisms, soils, and sediments of the northern hemisphere (Keeling et al., 1982; Siegenthaler and Sarmiento, 1993; Stallard, 1998). Soil organic matter is a big, rapidly cycling reservoir, likely to include much of this missing sink.During the geological past, the sizes of, and fluxes between, these reservoirs have varied enormously as the world has alternated between greenhouse times of high carbon content of the atmosphere, and icehouse times of low carbon content of the atmosphere. Oscillations in the atmospheric

  1. Physics in space-time with scale-dependent metrics

    NASA Astrophysics Data System (ADS)

    Balankin, Alexander S.

    2013-10-01

    We construct three-dimensional space Rγ3 with the scale-dependent metric and the corresponding Minkowski space-time Mγ,β4 with the scale-dependent fractal (DH) and spectral (DS) dimensions. The local derivatives based on scale-dependent metrics are defined and differential vector calculus in Rγ3 is developed. We state that Mγ,β4 provides a unified phenomenological framework for dimensional flow observed in quite different models of quantum gravity. Nevertheless, the main attention is focused on the special case of flat space-time M1/3,14 with the scale-dependent Cantor-dust-like distribution of admissible states, such that DH increases from DH=2 on the scale ≪ℓ0 to DH=4 in the infrared limit ≫ℓ0, where ℓ0 is the characteristic length (e.g. the Planck length, or characteristic size of multi-fractal features in heterogeneous medium), whereas DS≡4 in all scales. Possible applications of approach based on the scale-dependent metric to systems of different nature are briefly discussed.

  2. Geologic map of the east half of the Lime Hills 1:250,000-scale quadrangle, Alaska

    USGS Publications Warehouse

    Gamble, Bruce M.; Reed, Bruce L.; Richter, Donald H.; Lanphere, Marvin A.

    2013-01-01

    This map is compiled from geologic mapping conducted between 1985 and 1992 by the U.S. Geological Survey as part of the Alaska Mineral Resource Assessment Program. That mapping built upon previous USGS work (1963–1988) unraveling the magmatic history of the Alaska–Aleutian Range batholith. Quaternary unit contacts depicted on this map are derived largely from aerial-photograph interpretation. K-Ar ages made prior to this study have been recalculated using 1977 decay constants. The east half of the Lime Hills 1:250,000-scale quadrangle includes part of the Alaska–Aleutian Range batholith and several sequences of sedimentary rocks or mixed sedimentary and volcanic rocks. The Alaska–Aleutian Range batholith contains rocks that represent three major igneous episodes, (1) Early and Middle Jurassic, (2) Late Cretaceous and early Tertiary, and (3) middle Tertiary; only rocks from the latter two episodes are found in this map area. The map area is one of very steep and rugged terrain; elevations range from a little under 1,000 ft (305 m) to 9,828 ft (2,996 m). Foot traverses are generally restricted to lowermost elevations. Areas suitable for helicopter landings can be scarce at higher elevations. Most of the area was mapped from the air, supplemented by direct examination of rocks where possible. This restricted access greatly complicates understanding some of the more complex geologic units. For example, we know there are plutons whose compositions vary from gabbro to granodiorite, but we have little insight as to how these phases are distributed and what their relations might be to each other. It is also possible that some of what we have described as compositionally complex plutons might actually be several distinct intrusions.

  3. Inferring synaptic structure in presence of neural interaction time scales.

    PubMed

    Capone, Cristiano; Filosa, Carla; Gigante, Guido; Ricci-Tersenghi, Federico; Del Giudice, Paolo

    2015-01-01

    Biological networks display a variety of activity patterns reflecting a web of interactions that is complex both in space and time. Yet inference methods have mainly focused on reconstructing, from the network's activity, the spatial structure, by assuming equilibrium conditions or, more recently, a probabilistic dynamics with a single arbitrary time-step. Here we show that, under this latter assumption, the inference procedure fails to reconstruct the synaptic matrix of a network of integrate-and-fire neurons when the chosen time scale of interaction does not closely match the synaptic delay or when no single time scale for the interaction can be identified; such failure, moreover, exposes a distinctive bias of the inference method that can lead to infer as inhibitory the excitatory synapses with interaction time scales longer than the model's time-step. We therefore introduce a new two-step method, that first infers through cross-correlation profiles the delay-structure of the network and then reconstructs the synaptic matrix, and successfully test it on networks with different topologies and in different activity regimes. Although step one is able to accurately recover the delay-structure of the network, thus getting rid of any a priori guess about the time scales of the interaction, the inference method introduces nonetheless an arbitrary time scale, the time-bin dt used to binarize the spike trains. We therefore analytically and numerically study how the choice of dt affects the inference in our network model, finding that the relationship between the inferred couplings and the real synaptic efficacies, albeit being quadratic in both cases, depends critically on dt for the excitatory synapses only, whilst being basically independent of it for the inhibitory ones. PMID:25807389

  4. Multi-Scale Scratch Analysis in Qinghai-Tibet Plateau and its Geological Implications

    NASA Astrophysics Data System (ADS)

    Sun, Yanyun; Yang, Wencai; Yu, Changqing

    2016-04-01

    Multi-scale scratch analysis on a regional gravity field is a new data processing system for depicting three-dimensional density structures and tectonic features. It comprises four modules including the spectral analysis of potential fields, multi-scale wavelet analysis, density distribution inversion, and scratch analysis. The multi-scale scratch analysis method was applied to regional gravity data to extract information about the deformation belts in the Qinghai-Tibet Plateau, which can help reveal variations of the deformation belts and plane distribution features from the upper crust to the lower crust, provide evidence for the study of three-dimensional crustal structures, and define distribution of deformation belts and mass movement. Results show the variation of deformation belts from the upper crust to the lower crust. The deformation belts vary from dense and thin in the upper crust to coarse and thick in the lower crust, demonstrating that vertical distribution of deformation belts resembles a tree with a coarse and thick trunk in the lower part and dense and thin branches at the top. The dense and thin deformation areas in the upper crust correspond to crustal shortening areas, while the thick and continuous deformation belts in the lower crust indicate the structural framework of the plateau. Additionally, the lower crustal deformation belts recognized by the multi-scale scratch analysis coincide approximately with the crustal deformation belts recognized using single-scale scratch analysis. However, deformation belts recognized by the latter are somewhat rough while multi-scale scratch analysis can provide more detailed and accurate results.

  5. A methane-based time scale for Vostok ice

    NASA Astrophysics Data System (ADS)

    Ruddiman, William F.; Raymo, Maureen E.

    2003-02-01

    Tuning the Vostok methane signal to mid-July 30°N insolation yields a new ice-core gas time scale. This exercise has two rationales: (1) evidence supporting Kutzbach's theory that low-latitude summer insolation in the northern hemisphere controls the strength of tropical monsoons, and (2) interhemispheric CH 4 gradients showing that the main control of orbital-scale CH 4 variations is tropical (monsoonal) sources. The immediate basis for tuning CH 4 to mid-July insolation is the coincident timing of the most recent (pre-anthropogenic) CH 4 maximum at 11,000-10,500 calendar years ago and the most recent July 30°N insolation maximum (all ages in this paper are in calendar years unless specified as 14C years). The resulting CH 4 gas time scale diverges by as much as 15,000 years from the GT4 gas time scale (Petit et al., Nature 399 (1999) 429) prior to 250,000 years ago, but it matches fairly closely a time scale derived by tuning ice-core δ18O atm to a lagged insolation signal (Shackleton, Science 289 (2000) 1897). Most offsets between the CH 4 and δ18O atm time scales can be explained by assuming that tropical monsoons and ice sheets alternate in controlling the phase of the δ18O atm signal. The CH 4 time scale provides an estimate of the timing of the Vostok CO 2 signal against SPECMAP marine δ18O, often used as an index of global ice volume. On the CH 4 time scale, all CO 2 responses are highly coherent with SPECMAP δ18O at the orbital periods. CO 2 leads δ18O by 5000 years at 100,000 years (eccentricity), but the two signals are nearly in-phase at 41,000 years (obliquity) and 23,000 years (precession). The actual phasing between CO 2 and ice volume is difficult to infer because of likely SST overprints on the SPECMAP δ18O signal. CO 2 could lead, or be in phase with, ice volume, but is unlikely to lag behind the ice response.

  6. Trends in Surface Radiation Budgets at Climatic Time Scales

    NASA Astrophysics Data System (ADS)

    Pinker, Rachel T.; Zhang, Banglin; Ma, Yingtao

    2015-04-01

    For assessment of variability and trends in the Earth Radiation Balance, information is needed at climatic time scales. Satellite observations have been instrumental for advancing the understanding of the radiative balance at global scale, however, due to the frequent changes in the observing systems, the length of available satellite records is limited. In this paper we report on an effort to synthesize satellite observations from independent sources to estimates shortwave, longwave and spectral surface radiative fluxes at climatic time scales and use them to learn about their variability and trends. The radiative fluxes were derived in the framework of the MEaSURES and NEWS programs; they are evaluated against ground observations and compared to independent satellite and model estimates. Attention is given to updates on the radiative balance as compared to what is known from shorter time records and from models.

  7. Segregation time-scales in model granular flows

    NASA Astrophysics Data System (ADS)

    Staron, Lydie; Phillips, Jeremy C.

    2016-04-01

    Segregation patterns in natural granular systems offer a singular picture of the systems evolution. In many cases, understanding segregation dynamics may help understanding the system's history as well as its future evolution. Among the key questions, one concerns the typical time-scales at which segregation occurs. In this contribution, we present model granular flows simulated by means of the discrete Contact Dynamics method. The granular flows are bi-disperse, namely exhibiting two grain sizes. The flow composition and its dynamics are systematically varied, and the segregation dynamics carefully analyzed. We propose a physical model for the segregation that gives account of the observed dependence of segregation time scales on composition and dynamics. References L. Staron and J. C. Phillips, Stress partition and micro-structure in size-segregating granular flows, Phys. Rev. E 92 022210 (2015) L. Staron and J. C. Phillips, Segregation time-scales in bi-disperse granular flows, Phys. Fluids 26 (3), 033302 (2014)

  8. An algorithm for the Italian atomic time scale

    NASA Technical Reports Server (NTRS)

    Cordara, F.; Vizio, G.; Tavella, P.; Pettiti, V.

    1994-01-01

    During the past twenty years, the time scale at the IEN has been realized by a commercial cesium clock, selected from an ensemble of five, whose rate has been continuously steered towards UTC to maintain a long term agreement within 3 x 10(exp -13). A time scale algorithm, suitable for a small clock ensemble and capable of improving the medium and long term stability of the IEN time scale, has been recently designed taking care of reducing the effects of the seasonal variations and the sudden frequency anomalies of the single cesium clocks. The new time scale, TA(IEN), is obtained as a weighted average of the clock ensemble computed once a day from the time comparisons between the local reference UTC(IEN) and the single clocks. It is foreseen to include in the computation also ten cesium clocks maintained in other Italian laboratories to further improve its reliability and its long term stability. To implement this algorithm, a personal computer program in Quick Basic has been prepared and it has been tested at the IEN time and frequency laboratory. Results obtained using this algorithm on the real clocks data relative to a period of about two years are presented.

  9. Evaluation of Scaling Invariance Embedded in Short Time Series

    PubMed Central

    Pan, Xue; Hou, Lei; Stephen, Mutua; Yang, Huijie; Zhu, Chenping

    2014-01-01

    Scaling invariance of time series has been making great contributions in diverse research fields. But how to evaluate scaling exponent from a real-world series is still an open problem. Finite length of time series may induce unacceptable fluctuation and bias to statistical quantities and consequent invalidation of currently used standard methods. In this paper a new concept called correlation-dependent balanced estimation of diffusion entropy is developed to evaluate scale-invariance in very short time series with length . Calculations with specified Hurst exponent values of show that by using the standard central moving average de-trending procedure this method can evaluate the scaling exponents for short time series with ignorable bias () and sharp confidential interval (standard deviation ). Considering the stride series from ten volunteers along an approximate oval path of a specified length, we observe that though the averages and deviations of scaling exponents are close, their evolutionary behaviors display rich patterns. It has potential use in analyzing physiological signals, detecting early warning signals, and so on. As an emphasis, the our core contribution is that by means of the proposed method one can estimate precisely shannon entropy from limited records. PMID:25549356

  10. Going up in time and length scales in modeling polymers

    NASA Astrophysics Data System (ADS)

    Grest, Gary S.

    Polymer properties depend on a wide range of coupled length and time scales, with unique macroscopic viscoelastic behavior stemming from interactions at the atomistic level. The need to probe polymers across time and length scales and particularly computational modeling is inherently challenging. Here new paths to probing long time and length scales including introducing interactions into traditional bead-spring models and coarse graining of atomistic simulations will be compared and discussed. Using linear polyethylene as a model system, the degree of coarse graining with two to six methylene groups per coarse-grained bead derived from a fully atomistic melt simulation were probed. We show that the degree of coarse graining affects the measured dynamic. Using these models we were successful in probing highly entangled melts and were able reach the long-time diffusive regime which is computationally inaccessible using atomistic simulations. We simulated the relaxation modulus and shear viscosity of well-entangled polyethylene melts for scaled times of 500 µs. Results for plateau modulus are in good agreement with experiment. The long time and length scale is coupled to the macroscopic viscoelasticity where the degree of coarse graining sets the minimum length scale instrumental in defining polymer properties and dynamics. Results will be compared to those obtained from simple bead-spring models to demonstrate the additional insight that can be gained from atomistically inspired coarse grained models. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.