An inexpensive system for continuous lake core photography     

Kyle McMillan 《Journal of Paleolimnology》2008,40(4):1179-1184

Representative images of split sediment cores document geological records, serve as visual aids for multimedia, and provide samples for image analysis. Existing core imaging systems, often containing integrated hardware and software, are capable of providing excellent images; unfortunately these systems are also bulky and expensive, and are therefore limited to labs that process large volumes of core and those actively involved in image analysis. For most research groups such systems are unfeasible to buy and maintain. Producing good quality core images with a hand-held digital camera is very difficult without a consistent lighting source, and changes in camera angle (in all three spatial dimensions) between photographs may prevent accurate image compositing. Tripods allow for camera stability, but typically do not accommodate downward-facing photography. Presented here is an easily constructed core-imaging system that minimizes many of the drawbacks of personal digital cameras. Software necessary for using this system is readily available and can be run from a personal computer.  相似文献   

Graphical methods of river profile analysis to unravel drainage area change,uplift and erodibility contrasts in the Central Range of Taiwan          下载免费PDF全文

Chia‐Yu Chen  Sean D. Willett 《地球表面变化过程与地形》2016,41(15):2223-2238

To reveal river channel steepness patterns and variance in settings with significant variation in rock uplift rate, rock erodibility and moving water divides, we present a series of graphical methods to interpret channel profiles. To complement Cartesian χ plots, longitudinal profiles and mapping methods, we introduce a new method based on a radial coordinate system. We map each basin onto polar coordinates in which the radial dimension is χ and the azimuthal coordinate, ?, is calculated with an increment (Δ?) scaled to the distance to neighboring channel heads. The elevation is contoured on this mapping. Average channel steepness is estimated by fitting a conical surface to the elevation. The graph simplifies the comparison of χ and elevation between channels that share a divide, and helps identify spatial changes in drainage area and patterns of erodibility. We apply this approach to derive the uplift pattern in the eastern and southern Central Range of Taiwan, where the high tectonic convergence and uplift rates combined with sub‐tropical climate and frequent typhoons results in high exhumation rate, and well‐developed, detachment‐limited river networks. Additionally, the tectonic activity leads to drainage basin reorganization. We identify examples of divide migration, discrete river capture as well as anomalous steepness that we attribute to local variability in rock erodibility. Estimated basin‐average steepness values show the highest and a near constant value from Hsinwulu basin to Liwu basin in the center of the Island. To the north and south of this region, the values gradually decrease. These estimates show good correlation with the topography of the Central Range and erosion rates derived from in situ ¹⁰Be concentrations in river‐borne quartz. We conclude that the basin steepness reflects systematic differences in rock uplift rate and erosion rate. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Use of a vertical δ18O profile to constrain hydraulic properties and recharge rates across a glacio-lacustrine unit, Nantucket Island, Massachusetts, USA     

Mark Person  Andee Marksamer  Brandon Dugan  Peter E. Sauer  Kyle Brown  David Bish  Kathy J. Licht  Mark Willett 《Hydrogeology Journal》2012,20(2):325-336

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Combined L1/L2 Kalman filter-based tracking scheme for weak signal environments     

Cyrille?Gernot  Kyle?O’KeefeEmail author  Gérard?Lachapelle 《GPS Solutions》2011,15(4):403-414

A Kalman filter-based method combining the energy of both L1 C/A and L2C GPS signals in a combined tracking loop method to enhance performance under adverse conditions is developed. Standard tracking methods and the ionospheric effect on GPS signals are reviewed and compared to a new Kalman filter that simultaneously estimates delay, phase and total electron content by combining L1 C/A and L2C code and phase discriminator outputs. The new filter is tested and compared to standard methods for tracking L1 C/A and L2C using both simulated and real data. The new method is found to have improved sensitivity of 3 dB compared to standard L1 tracking and 4.5 dB compared to standard L2C tracking while at the same time providing an accurate estimate of the total electron content along the signal path.  相似文献   

Sedimentology of early Pliocene sandstones in the south-western Taiwan foreland: Implications for basin physiography in the early stages of collision     

Sébastien Castelltort  Stefan Nagel  Frédéric Mouthereau  Andrew Tien-Shun Lin  Andreas Wetzel  Boris Kaus  Sean Willett  Shao-Ping Chiang  Wei-Yi Chiu 《Journal of Asian Earth Sciences》2011,40(1):52-71

This work presents sedimentological observations and interpretations on three detailed sections of the Pliocene Yutengping/Ailiaochiao formations, deposited in the early stages of collision in Taiwan. Seven facies associations record paleoenvironments of deposition ranging from nearshore to lower offshore with a strong influence of tidal reworking, even in shelfal sub-tidal environments, and a pro-delta setting characterized by mass-flows. The association of shallow facies of the upper offshore to lower shoreface with pro-delta turbidite facies sourced in the orogen to the east suggests a peculiar setting in which turbidite deposition occurred below wave base but on the shelf, in water depths of probably less than 100 m. This adds to the examples of “shallow turbidites” increasingly commonly found in foreland basins and challenges the classical view of a “deep” early underfilled foreland basin. Time series analysis on tidal rhythmites allow us to identify a yearly signal in the form of periodic changes of sand-supply, energy and bioturbation that suggests a marked seasonality possibly affecting precipitation and sediment delivery as well as temperature. The Taiwan foreland basin may also present a potentially high-resolution record in shallow sediments of the early installation of monsoonal circulation patterns in east Asia. We confirm partly the paleogeography during the early stages of collision in Taiwan: the Chinese margin displayed a pronounced non-cylindrical geometry with a large basement promontory to the west in place of the modern Taiwan mountain range. Collision in Taiwan may have happened at once along the whole length of the modern mountain range, instead of progressively from north to south as classically considered.  相似文献   

Quantifying the influence of channel sinuosity on the depositional mechanics of channelized turbidity currents: A laboratory study     

Kyle M. Straub  David MohrigJames Buttles  Brandon McElroyCarlos Pirmez 《Marine and Petroleum Geology》2011,28(3):744-760

Here we present results from a suite of laboratory experiments that highlight the influence of channel sinuosity on the depositional mechanics of channelized turbidity currents. We released turbidity currents into three channels in an experimental basin filled with water and monitored current properties and the evolution of topography via sedimentation. The three channels were similar in cross-sectional geometry but varied in sinuosity. Results from these experiments are used to constrain the run-up of channelized turbidity currents on the outer banks of moderate to high curvature channel bends. We find that a current is unlikely to remain contained within a channel when the kinetic energy of a flow exceeds the potential energy associated with an elevation gain equal to the channel relief; setting an effective upper limit for current velocity. Next we show that flow through bends induces a vertical mixing that redistributes suspended sediment back into the interiors of depositional turbidity currents. This mixing counteracts the natural tendency for suspended sediment concentration and grain size to stratify vertically, thereby reducing the rate at which sediment is lost from a current via deposition. Finally, the laboratory experiments suggest that turbidity currents might commonly separate from channel sidewalls along the inner banks of bends. In some cases, sedimentation rates and patterns within the resulting separation zones are sufficient to construct bar forms that are attached to the channel sidewalls and represent an important mechanism of submarine channel filling. These bar forms have inclined strata that might be mistaken for the deposits of point bars and internal levees, even though the formation mechanism and its implications to channel history are different.  相似文献   

Refinement of the late Quaternary geologic history of Erebus volcano,Antarctica using Ar/Ar and Cl age determinations     

Peter J. Kelly  Nelia W. Dunbar  Philip R. Kyle  William C. McIntosh 《Journal of Volcanology and Geothermal Research》2008

Six new ⁴⁰Ar/³⁹Ar and three cosmogenic ³⁶Cl age determinations provide new insight into the late Quaternary eruptive history of Erebus volcano. Anorthoclase from 3 lava flows on the caldera rim have ⁴⁰Ar/³⁹Ar ages of 23 ± 12, 81 ± 3 and 172 ± 10 ka (all uncertainties 2σ). The ages confirm the presence of a second, younger, superimposed caldera near the southwestern margin of the summit plateau and show that eruptive activity has occurred in the summit region for 77 ± 13 ka longer than previously thought. Trachyte from “Ice Station” on the eastern flank is 159 ± 2 ka, similar in age to those at Bomb Peak and Aurora Cliffs. The widespread occurrences of trachyte on the eastern flank of Erebus suggest a major previously unrecognized episode of trachytic volcanism. The trachyte lavas are chemically and isotopically distinct from alkaline lavas erupted contemporaneously in the summit region < 5 km away.  相似文献   

Volcanic emissions of metals and halogens from White Island (New Zealand) and Erebus volcano (Antarctica) determined with chemical traps     

L.J. Wardell  P.R. Kyle  D. Counce 《Journal of Volcanology and Geothermal Research》2008

Volcanic emission rates of As, Sb, Pb, Hg, Se, Cl, and F were determined at Erebus volcano, Antarctica and White Island, New Zealand, using chemical traps. The trace metal fluxes were determined by combining the species to S ratios in the solutions with SO₂ emission rates measured by correlation spectrometry at the two volcanoes. At Erebus volcano, fluxes for the metals Pb and Hg were 2.0 × 10^− 4 and 8.1 × 10^− 6 kg s^− 11, respectively. Fluxes for Cl, F, As, Sb and Se (0.35, 0.15, 2.5 × 10^− 4, 1.2 × 10^− 5, and 4.5 × 10^− 6 kg s^− 1, respectively) agreed within error limits for values determined previously by the LiOH impregnated filter method [Zreda-Gostynska, G., Kyle, P., Finnegan, D., Prestbo, K., 1997. Volcanic gas emissions from Mount Erebus and their impact on the Antarctic environment. Journal of Geophysical Research, 102(B7): 15039–15055.], demonstrating the utility of the chemical trap method. A fall in the As/S ratio from 7 × 10^− 4 in 1997/1999 to 3 × 10^− 4 in 2000 at Erebus coincided with a change in the frequency and style of eruptive activity that may have been due to injection of magma into the system. At White Island, chemical trap data indicated fluxes of Cl = 0.90, F = 0.0079, Pb = 2.7 × 10^− 4, Hg = 1.1 × 10^− 5, As = 1.3 × 10^− 4, Sb = 1.9 × 10^− 5 and Se = 1.5 × 10^− 5 kg s^− 1. Samples collected 600 m downwind of the active crater were comparable to samples collected adjacent to the main gas vent, showing that this method can still be used at some distance from a degassing vent.  相似文献   

Differential developmental toxicity of naphthoic acid isomers in medaka (Oryzias latipes) embryos   总被引：1，自引：0，他引：1  

Michael W. Carney  Kyle Erwin  Ron Hardman  Bonny Yuen  David C. Volz  David E. Hinton  Seth W. Kullman   《Marine pollution bulletin》2008,57(6-12):255

Polycyclic aromatic hydrocarbons (PAHs) are widespread persistent pollutants that readily undergo biotic and abiotic conversion to numerous transformation products in rivers, lakes and estuarine sediments. Here we characterize the developmental toxicity of four PAH transformation products each structural isomers of hydroxynaphthoic acid: 1H2NA, 2H1NA, 2H3NA, and 6H2NA. Medaka fish (Oryzias latipes) embryos and eleutheroembryos were used to determine toxicity. A 96-well micro-plate format was used to establish a robust, statistically significant platform for assessment of early life stages. Individual naphthoic acid isomers demonstrated a rank order of toxicity with 1H2NA > 2H1NA > 2H3NA > 6H2NA being more toxic. Abnormalities of circulatory system were most pronounced including pericardial edema and tube heart. To determine if HNA isomers were AhR ligands, spatial-temporal expression and activity of CYP1A was measured via in vivo EROD assessments. qPCR measurement of CYP1A induction proved different between isomers dosed at respective concentrations affecting 50% of exposed individuals (EC50s). In vitro, all ANH isomers transactivated mouse AhR using a medaka CYP1A promoter specific reporter assay. Circulatory abnormalities followed P450 induction and response was consistent with PAH toxicity. A 96-well micro-plates proved suitable as exposure chambers and provided statistically sound evaluations as well as efficient toxicity screens. Our results demonstrate the use of medaka embryos for toxicity analysis thereby achieving REACH objectives for the reduction of adult animal testing in toxicity evaluations.  相似文献   

Comparison of flood hazard assessments on desert piedmonts and playas: A case study in Ivanpah Valley, Nevada   总被引：1，自引：0，他引：1  

Colin R. Robins  Brenda J. Buck  Amanda J. Williams  Janice L. Morton  P. Kyle House  Michael S. Howell  Maureen L. Yonovitz 《Geomorphology》2009,103(4):520-532

Accurate and realistic characterizations of flood hazards on desert piedmonts and playas are increasingly important given the rapid urbanization of arid regions. Flood behavior in arid fluvial systems differs greatly from that of the perennial rivers upon which most conventional flood hazard assessment methods are based. Additionally, hazard assessments may vary widely between studies or even contradict other maps. This study's chief objective was to compare and evaluate landscape interpretation and hazard assessment between types of maps depicting assessments of flood risk in Ivanpah Valley, NV, as a case study. As a secondary goal, we explain likely causes of discrepancy between data sets to ameliorate confusion for map users. Four maps, including three different flood hazard assessments of Ivanpah Valley, NV, were compared: (i) a regulatory map prepared by FEMA, (ii) a soil survey map prepared by NRCS, (iii) a surficial geologic map, and (iv) a flood hazard map derived from the surficial geologic map, both of which were prepared by NBMG. GIS comparisons revealed that only 3.4% (33.9 km²) of Ivanpah Valley was found to lie within a FEMA floodplain, while the geologic flood hazard map indicated that ~ 44% of Ivanpah Valley runs some risk of flooding (Fig. 2D). Due to differences in mapping methodology and scale, NRCS data could not be quantitatively compared, and other comparisons were complicated by differences in flood hazard class criteria and terminology between maps. Owing to its scale and scope of attribute data, the surficial geologic map provides the most useful information on flood hazards for land-use planning. This research has implications for future soil geomorphic mapping and flood risk mitigation on desert piedmonts and playas. The Ivanpah Valley study area also includes the location of a planned new international airport, thus this study has immediate implications for urban development and land-use planning near Las Vegas, NV.  相似文献