Chi-square tests for markov chain analysis

Markov chain analysis has become a popular and useful technique for the evaluation of stratigraphic information. Field data on frequencies of facies transitions are first assembled in a transition count matrix. Observed frequencies can be compared statistically with frequencies expected if no order, or memory, exists in the stratigraphic sequence. Two chi-square (²) tests have been proposed for this purpose. One of the previously proposed ² tests was observed to give anomalously large values of the test statistic during another study. This unsatisfactory behavior is verified here. Limiting values of the two ² tests (from tables) are compared with the distribution of values for both test statistics obtained by analyzing many random matrices generated by a simple computer program. In all cases, the logarithmic ² test, suggested by several previous authors, fails to provide any meaningful assessment of the presence or absence of order in stratigraphic sequences evaluated. Further use of this test should therefore be avoided.     

Tests for quasi-independence of embedded markov chains

This paper introduces the concept of quasi-independence into embedded Markov chains and identifies the maximum likelihood frequency estimates to be used with ² tests of the null hypothesis of quasi-independence within an embedded Markov chain.     

NOAA Weather Radio (NWR) – A Coastal Solution to Tsunami Alert and Notification

The Washington State/Local Tsunami Work Group adopted the NOAA Weather Radio All-Hazards Warning System to warn citizens quickly and effectively of not only tsunami hazards but also other natural or man-made hazards. In concert with an array of deep ocean tsunami detectors, land-based seismic sensors, and warning messages issued by the tsunami warning centers, NWR provides a means to expeditiously get critical decision-making information to emergency managers, elected officials, and first responders. To implement the NWR strategy effectively, a partnership was developed to add a repeater to the NWR system to provide complete coverage to the coast of Washington and to shipping lanes off the coast. The Work Group also recognized the need to disseminate time critical hazard information on tsunamis to the public on beaches and in high traffic areas, so it developed a new notification system, with the first prototype installed on 2 July 2003 in Ocean Shores, Washington. A public education program also was developed to improve the impacted communities understanding of the tsunami hazard, the warning system, and actions they should take if a tsunami occurs.     

On the reliability of different methods of seismic hazard assessment in Greece

Historical and present century instrumental data have been used to determine seismic hazard in 35 sites of Greece by the application of Cornell's method (Cornell, 1968) and the mean value method. The macroseismic intensity has been considered as a measure of seismic hazard. Comparison of the results of the two methods showed that, in general, the mean value method gives higher values, particularly for low probabilities of exceedance. In addition, for some sites, the differences of the expected intensities resulting from the two methods, indicate that finer tuning of the seismogenic souce model is required, or suggest time dependence. Although each one of these methods has its own merits, the method based on seismic zonation (Cornell's method) has several advantages and must be preferred when an accurate zonation is possible by the use of macroseismic and instrumental seismic data, together with geological and geomorphological information. However, reliable estimates of seismic hazard at a particular site require work on a microzoning scale, incorporating historical, archaeological, and recent geological data.Paper presented at the 21st General Assembly of the European Seismological Commission held in Sofia, 1988.     

Local Sensitivity Analysis of a Numerical Model of Volcanic Plinian Columns through Automatic Differentiation

Numerical simulation of geological phenomena are nowadays widely used to understand them. A good example are the numerous codes developed to model mass motion in different processes. Such models are approximations to the real phenomena because the physical conditions are simplified or because the values of the parameters intervening in the modeling are known only approximately. For this reason, an obligatory step in the application of these models is the assessment of their sensitivity to changes in the parameters. Sensitivity analysis is also required to evaluate the influence of the different input variables in the outcome of the model. In general this analysis is carried out by repeated computation of the model to different sets of input variables and settings of the model. A more fruitful procedure to carry out such analysis can be achieved by automatic differentiation. In this paper we illustrate such approach through its application to the model of an eruptive plinian column. The results of the analysis allow to assess, in a systematic and efficient manner, the relevance of the different boundary values and parameters of the model. The analysis reveals the effects on velocity, temperature, gas fraction, radius and ultimately column height, by changes in their boundary value (i.e. at the vent). The effect of changes in the value of the gas constants, density of pyroclasts and specific heat of the erupted material is also evidenced. Alternatively, the results can be regarded as a mean to estimate the values of the variables for different set of boundary values without recurring to new runs of the model. Automatic differentiation is shown to be a convenient scheme to obtain derivatives of model variables. This type of analysis forms in addition the basis for further work in inversion schemes.     

Identifying sources of groundwater in the lower Colorado River valley, USA, with δ18O, δD, and 3H: implications for river water accounting

Isotope measurements (¹⁸O, D, ³H) indicate groundwater origin in the Lower Colorado River Valley (LCRV) and provide an alternative, or supplement, to the US Bureau of Reclamations proposed accounting surface method. The accounting surface method uses a hydraulic criterion to identify certain wells away from the flood plain that will eventually yield mainstream Colorado River water. New isotope data for 5 surface-water and 18 groundwater sites around Topock Marsh, Arizona, are compared with river-water data (1974–2002) from 11 sites between Utah and Mexico and with groundwater data from previous LCRV studies. Three groundwater sources are repeatedly identified in the LCRV: (1) local recharge derived from precipitation, usually winter rain, plots slightly below the global meteoric water line (GMWL) and has D values that are 20 greater than those of recent river water; (2) older (pre-1950) upper basin river-water plots on or near the GMWL, distinct from local rainfall and recent river water; and (3) recent (post-1950) Colorado River water, including Topock Marsh samples, plots below the GMWL along an evaporation trend. Large floods, as in 1983, complicate interpretation by routing less evaporated upper basin water into the LCRV; however, tritium content can indicate the age of a water. River-water tritium has declined steadily from its peak of 716 TU in 1967 to about 11 TU in 2002. Mixtures of all three groundwater sources are common.

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Resumen Mediciones isotópicas (¹⁸O, D, ³H) indican cual es el origen del agua subterránea en el Valle Bajo del Río Colorado (LCRV) y aportan una alternativa, o complemento, para el método superficie de conteo propuesto por el Buró de Reclamación de Estados Unidos. El método superficie de conteo utiliza un criterio hidráulico para identificar ciertos pozos alejados de la planicie de inundación que eventualmente producirán agua a partir de la corriente principal del Río Colorado. Los nuevos datos isotópicos para 18 sitios de agua subterránea y 5 sitios de agua superficial cerca de los Pantanos Topock, Arizona, se comparan con datos de agua de río (1974–2002) provenientes de 11 sitios localizados entre Utah y México, y con datos de aguas subterráneas de estudios previos realizados en el LCRV. Se identifican reiteradamente tres fuentes de aguas subterráneas en el LCRV: (1) recarga local derivada de precipitación, generalmente lluvia de invierno, cuya composición cae ligeramente por debajo de la línea de agua meteórica global (GMWL) y tiene valores D que son 20 mayores que los reportados para agua de río reciente; (2) el agua de río más vieja (pre-1950) de la cuenca alta cuya composición cae sobre o cerca de la GMWL, diferente de la lluvia local y del agua de río reciente; (3) agua reciente (post-1950) del Río Colorado, incluyendo muestras de los Pantanos Topock, con composición por debajo de la GMWL a lo largo de una tendencia a la evaporación. Inundaciones grandes, como en 1983, complican la interpretación al transmitir menos agua evaporada de la cuenca alta hacia el LCRV; sin embargo, el contenido de tritio puede indicar la edad del agua. El contenido de tritio en agua de río ha disminuido constantemente desde la concentración pico de 716 TU en 1967 a cerca de 11 TU en 2002. Es común que exista mezclas de las tres fuentes de agua subterránea.

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Résumé Les mesures isotopiques (d18O, dD, 3H) indiquent les origine de leaux souterraines dans la Vallée de la Rivière du Bas Colorado (LCRV) et sont une alternative, ou un supplément, à la méthode des bilans hydrologiques proposée par du «US Bureau of Reclamation». Cette méthode de bilan hydrologique utilise un critère hydraulique permettant didentifier certains puits hors de la plaine dinondation qui pomperaient une part non négligeable de leur eau dans la rivière Colorado. De nouvelles données isotopiques provenant de 5 sites deau de surface et 18 deaux souterraines autour de Topock Marsh en Arizona, sont comparées avec les données (1974–2000) de 11 sites localisés entre Utah et Mexico, ainsi que des données dautres études sur la LCRV. Ces sources deaux souterraines sont identifiées à plusieurs reprises dans la LCRV: (1) la recharge locale dérivant des précipitations, généralement les pluies hivernales, se retrouvent légèrement sous la ligne deau météoritique globale (GMWL) et possède des valeurs de dD 20% supérieures aux valeurs des eaux récentes de la rivière; (2) les eaux vieilles (pre-1950) du bassin supérieur de la rivière possèdent une valeurs très proches de la GMWL, distinctes des valeurs de la pluie locale et des eaux récentes de la rivière; et (3) les eaux récentes (post-1950) de la Rivière Colorado, incluant les échantillons de Topock Marsh, se positionnent à côté de la GMWL sur une droite dévaporation. Les grandes inondations, par exemple celle de 1983, compliquent linterprétation en reprenant dans la LCRV moins deaux marquées comme évaporées et provenant du bassin supérieur; par ailleurs le pic de tritium est descendu de 716 TU en 1967 à 11 TU en 2002. Les mélanges de ces trois sources sont assez fréquentes.

     

New latest Cretaceous microvertebrate fossil assemblages from the Haţeg Basin (Romania)

Late Cretaceous terrestrial ecosystems in southern Europe are relatively poorly known, although much progress has been made during the past decade, principally with regard to the microvertebrate components of these ecosystems. The Maastrichtian terrestrial deposits of the Haeg Basin, at the easternmost end of the South European archipelago and well known for reptilian fossils (e.g., turtles, crocodilians, pterosaurs and dinosaurs), have been thoroughly screened during the past five years. Important microvertebrate assemblages, both quantitatively and qualitatively speaking, were found at Pui (Sînpetru Formation), Tutea and, particularly, Vlioara (Densu-Ciula Formation). Several new taxa are noted here for the first time for the Haeg Basin, including gars, discoglossids, albanerpetontids, scincomorphan and anguimorphan lizards; dromaeosaurids and multituberculates are confirmed. Most of the microvertebrate remains are poorly preserved and precise systematic assignment has proved difficult. The Haeg fauna appears to be primitive and endemic, with a Neopangean core composition, and suggests a composite palaeobiogeographic origin for the Late Cretaceous European ecosystems, confirming conclusions reached in studies of the larger vertebrates.     

A model for the statistical distribution of microlithotypes in coal

Microlithotype composition of a coal sample is often summarized by examining a large number (~500) of subsamples of a grain mount and estimating proportions of vitrite, intermediates, and inertite, where, for samples we have investigated, the proportion of intermediates is generally less than 0.4. This suggests that most subsamples are either greater than 95% vitrinite or greater than 95% inertinite, so that the statistical distribution of vitrinite has most of its weight in its tails. Two distributions which may have this shape are the beta and the logistic normal, and these have been fitted to the microlithotype distribution of some coal samples. Parameters of these fitted distributions are related to the proportion of vitrinite in the sample and thickness of microscopic bands in the coal. For coals in the Sydney Basin, at least, it was found that the parameter relating to band thickness is approximately constant over a coal seam; therefore, fitting one or other of these distributions to such data leads to directly interpretable parameters.     

Timing of low-temperature metamorphism and cooling of the Paleozoic and Mesozoic formations of the Bükkium,innermost Western Carpathians,Hungary

K-Ar ages of illite-muscovite and fission track ages of zircon and apatite were determined from various lithotypes of the Bükkium, which forms the innermost segment of the Western Carpathians. The stratigraphic ages of these Dinaric type formations cover a wide range from the Late Ordovician up to the Late Jurassic. The grade of the orogenic dynamo-thermal metamorphism varies from the late diagenetic zone through the anchizone up to the epizone (chlorite, maximally biotite isograd of the greenschist facies). The K-Ar system of the illite-muscovite in the < 2 m grain-size fraction approached equilibrium only in epizonal and high-temperature anchizonal conditions. The orogenic metamorphism culminated between the eo-Hellenic (160-120 Ma) phase connected to the beginning of the subduction in the Dinarides, and the Austrian (100-95 Ma) phase characterized by compressional crustal thickening. No isotope geochronological evidence was found for proving any Hercynian recrystallization. The stability field of fission tracks in zircon was approached using the thermal histories of the different tectonic units. A temperature less than 250°C and effective heating time of 20–30 Ma had only negligible effects on the tracks, whereas total annealing was reached between 250 and 300°C. Apatite fission track ages from the Paleozoic and Mesozoic formations show that the uplift of the Bükk Mountains occurred only in the Tertiary (not earlier than ca. 40 Ma ago). Thermal modeling based on apatite fission track length spectra and preserved Paleogene sediment thickness data proved that the Late Neogene burial of the recently exhumed plateau of the Bükk Mountains exceeded 1 km.     

Late Silurian fish microfossils from Helvetesgraven,Skåne (southern Sweden) (I)

Geologie en Mijnbouw - The fauna from a Late Silurian residue sample from Övedskloster (Skåne) is listed. It comprises scales of ‘Agnatha’ (rare osteostracan scales, and the...     

A study of the modelling error in two operator splitting algorithms for porous media flow

Operator splitting methods are often used to solve convection–diffusion problems of convection dominated nature. However, it is well known that such methods can produce significant (splitting) errors in regions containing self sharpening fronts. To amend this shortcoming, corrected operator splitting methods have been developed. These approaches use the wave structure from the convection step to identify the splitting error. This error is then compensated for in the diffusion step. The main purpose of the present work is to illustrate the importance of the correction step in the context of an inverse problem. The inverse problem will consist of estimating the fractional flow function in a onedimensional saturation equation.     

Vibrational spectroscopy of beta-eucryptite (LiAlSiO<Subscript>4</Subscript>): optical phonons and phase transition(s)

The structural behavior of -eucryptite (LiAlSiO₄) has been investigated using infrared (IR) spectroscopy over a temperature range of 20 to 900 K and FT-Raman spectroscopy at room temperature. IR reflectance measurements show that -eucryptite possesses high reflectivity in the far-IR region, as is consistent with its reported superionic conductivity along the c-axis. On heating, the Li-related IR bands near 246 and 300 cm^–1 (with A₂ symmetry) broadened and weakened dramatically, presumably as a result of Li⁺ positional disordering along the structural channels parallel to c. The disordering process appears to induce a framework distortion, as is evidenced by the broadening of some vibrations of Si(Al)–O with increasing temperature. A change in slope in the temperature dependence of the phonon frequency near 300 cm^–1 and the linewidth of the 760 cm^–1 band at 715 K indicates that Li becomes completely disordered above this temperature. In addition, the temperature dependence of the linewidth for the 760 cm^–1 band exhibits an additional change in slope at 780 K, implying the existence of an intermediate state within this temperature range. The detailed structure of this intermediate phase, however, needs further study. Our IR data provide no indication of structural changes between room temperature and 20 K.     

Valent state and coordination of cobalt Ions in beryl and chrysoberyl crystals

We have studied the polarized optical absorption and EPR spectra of Co-doped beryls grown by hydrothermal, flux, and gas-transport methods, and chrysoberyl grown by the Czochralski method. In beryls three groups of bands, belonging to three various Co centers, were distinguished by analysis of the absorption band intensities. The first group, bands with maxima at 22 220 (E c), 17 730 (E c), and 9090 (E c), 7520 (E c) cm^–1 are due to Co²⁺ in octahedral site of Al³⁺. The second group is bands at 18 940, 18 250, 17 700 (E c), 18 300, 17 700, 17 000 (E c) and 8830 (E c), 7350 (E c) cm^–1 and 5320 (E c), 3880 (E c) cm^–1, which are caused by Co²⁺ in tetrahedral site of Be²⁺. A weak wide band in flux and gas-transport beryl in the region of 12 500–8300 cm^–1 (E , c) is related to Co³⁺ in octahedral Al³⁺ site. In hydrothermal beryl, bands 13 200 (E c), 10 900 (E c), and 8500 (E c) cm^–1 are caused by an uncontrolled impurity of Cu²⁺ ions. For Co-doped chrysoberyl one type of center of Co has been established: Co²⁺ in the octahedral site of Al³⁺. In the approximation of the trigonal field with regard to Trees correction, the energy levels of Co²⁺ have been calculated in octahedral and tetrahedral coordination. There is good agreement between the obtained experimental and calculated data. The polarization dependence of the optical absorption bands is explained well in terms of the spin-orbit interaction.     

Oxidation and Origin of Organic Matter in Surficial Eastern Mediterranean Hemipelagic Sediments

Aerobic mineralisation of C_org in surface sedimentsof the deep (>2000 m water depth) eastern Mediterranean Sea has been quantified by analysis of detailedbox core C_org concentration versus depth profiles and the modelling environment for early diageneticproblems MEDIA. The reactive fraction comprises 60–80% of the total C_org reachingthe sediments and is largely oxidised within the surficial 10 cm. A non-reactive C _orgfraction (G_NR) dominates at depths >10 cm, and makes up20–40% of the total C _org flux to the sediments. First-order rateconstants for decomposition of the reactive fraction calculated from theC _org profiles range from 5.4 × 10^-3 to8.0 × 10^-3 y^-1 to 8.0 × 10^-3 y^-1. Total mineralization rates in thesurface sediment are between 1.7 and 2.6 mol C cm^-2 y^-1 and thus are typical for oligotrophic, deep-seaenvironments. The low fluxes and rapid remineralisation of C _org are accompanied by²¹⁰Pb_excess surface mixed layers which are only 2 cm deep, among the thinnest reported for oxygenated marine sediments.Model results indicate a mismatch between the C _org profiles and O₂ microprofileswhich were measured onboard ship. This can be attributed to a combination of decompression artefactsaffecting onboard measurement of the O₂ profiles or the leakage ofoxygen into the core during handling on deck. Furthermore, the used D_b values, based on ²¹⁰Pb, may not befully appropriate; calculations with higher D_b values improve the O₂ fits. The surficial sediment¹³C _org values of -22 become less negative with increasing depth and decreasing C _orgconcentrations. The major ¹³C change occurs in the top 3 to 4 cm and coincides with the interval weremost of the organic carbon oxidation takes place. This indicates that the reactive fractionof organic matter, commonly assumed to be marine, has a more negative ¹³C _orgthan the refractory fraction, usually held to be terrestrial. Palaeoproductivity estimates calculated from thesediment data by means of literature algorithms yield low surface productivities(12–88 gC m^-2 y^-1), which are in good agreement with field measurements of primary productivity in otherstudies. Such values are, however, significantly lower than those indicated by recent productivitymaps of the area derived from satellite imagery (>100 gC m^-2 y^-1).     

Selenium fractionation and speciation in rocks, soils, waters and plants in polluted surface mine environment

A fractionation and speciation was performed to determine the distribution of selenium (Se) species in major components of quartzite surface mine environment (rocks, mine tailings, soils, stream sediments, surface waters and plants) in obov, Slovakia. A three-step sequential extraction procedure was utilised for the fractionation of Se in mine tailings and soils. The first extractant in order to evaluate the soluble and ligand exchangeable fraction of Se (0.1 mol/l K₂HPO₄ + KH₂PO₄ at pH 7.0) solubilized up to 15% of total Se content. The second step (0.1 mol/l K₂S₂O₈ at 90°C) which extracted Se associated or occluded with organic matter released 13 – 45% of total selenium. The decomposition of the residue (HNO₃ + H₂SO₄ 1+1) was used to solubilize the remaining 35–88% of total Se as the final step. The recovery of the procedure was between 97 and 106%. Selenate predominated in natural river and lake waters about pH 7.0 (>95%) but in acid mine leakings up to 40% of selenite was found. In the plants (birch leaves, grass leaves and roots) collected from the area acidified by mine leakings no significant accumulation of selenium was observed. The correlation between total Se and S in the rocks from the mine gives an evidence of the common origin of these elements in the studied area.     

Radon in soil anomaly observed at Los Azufres geothermal field,Michoacan: a possible precursor of the 1985 Mexico earthquake (Ms = 8.1)

A radon anomaly in a nuclear track detector placed on a fault was detected prior to the destructive (Ms = 8.1) Mexican earthquake of 19 September 1985. The fault is a structural feature of the geothermal field Los Azufres, 260 km NE of the epicentral area. Since no other phenomenon can be found as a possible cause for the radon anomaly, it is proposed that preseismic regional stress perturbations may produce changes in the fluid transport patterns at the fault, suggesting that radon measurements in similar conditions could provide a good precursor in high seismic risk areas.     

Groundwater chemistry within a plateau neighboring Matsumoto city,Japan

The change in groundwater chemistry along the groundwater flow path in the Matsumoto tunnel vicinity was studied, and the origin of the groundwater and dissoluted substances was determined. The relationship between the concentration of HCO₃ ^–, Ca²⁺, and Na⁺, and CO₂ gas pressure in the groundwater indicated that the HCO₃ ^–, Ca²⁺, and Na⁺ were produced by the reaction of the CO₂ gas in the groundwater and feldspar in the rocks. The relationship between the concentration of NO₃ ^– and the Eh and pH values in the groundwater indicated that in an oxidative condition, ammonia-oxidizing and nitriteoxidizing bacteria used NH₄ ⁺ and produced NO₃ ^– and H⁺, and in a reductive condition, denitrifying bacteria used NO₃ ^– and produced N₂ gas and OH^–. The stable hydrogen and oxygen isotopic ratio in the groundwater and precipitation indicated that the groundwater originated from precipitation that had fallen on the area. The concentration of³H and the stable hydrogen and oxygen isotopic ratios in the groundwater suggested that it has been getting warmer climatically for more than 60 years. The stable carbon isotopic ratio indicated that the HCO₃ ^– in the groundwater, excluding deep well water, originated from CO₂ gas produced by organic matter in the soil. The deep well water, which had a higher concentration of HCO₃ ^– than the other groundwater sampled, was thought to have acquired HCO₃ ^– though contact with rocks. The³⁶Cl/Cl ratio indicated the recharge age of the deep well water sampled at a depth of 760 m at the foot of the plateau was recent.     

Isotope geochemistry of the Tieluping silver-lead deposit, Henan, China: A case study of orogenic silver-dominated deposits and related tectonic setting

The Tieluping silver deposit, which is sited along NE-trending faults within the high-grade metamorphic basement of the Xionger Terrane in the Qinling orogenic belt, is part of an important, recently discovered Mesozoic orogenic-type Ag-Pb belt. Ore formation includes three stages: an early barren quartz-pyrite stage (E), an intermediate polymetallic sulfide ore stage (M), and a late barren carbonate stage (L). Carbon, sulfur and lead isotope systematics indicate that the E-stage fluids are deeply sourced; the L-stage fluids are shallow-sourced meteoric water; whereas the M-stage fluids are a mix of deep-sourced and shallow-sourced fluids. Sulfur and lead isotope data show that the ore-forming fluids must have originated from a source with elevated radiogenic lead and low ³⁴S values, that differs significantly from exposed geologic units in the Xionger Terrane, the lower crust and the mantle. This supports the view that the carbonate-shale-chert sequences of the Guandaokou and Luanchuan Groups south of the Machaoying fault might be the favorable sources, although little is known about their isotopic compositions. A tectonic model that combines collisional orogeny, metallogeny and hydrothermal fluid flow is proposed to explain the formation of the Tieluping silver deposit. During the Mesozoic collision between the North China Craton and South China Block (Early-Mid Triassic Indosinian Orogeny), crustal slabs containing the carbonate-shale-chert sequences of the Guandaokou and Luanchuan Groups, locally rich in organic matter (carbonaceous shale), were thrust northwards beneath the Xionger Terrane along the Machaoying fault. Metamorphic devolatilisation of this underthrust slab probably provided the ore-forming fluids to develop the Ag-Pb ore belt, which includes the Tieluping silver deposit. Fluids and magmas were emplaced during extensional stages related to the Jurassic-Cretaceous Yanshanian Orogeny.Editorial Handling: B. Lehmann     

Analysis of oil lens removal by extraction through a seepage face

Removal of LNAPL (oil) from an aquifer is described using a multiphase flow model. At the well boundary seepage face conditions are imposed. These conditions are implemented in a numerical model and withdrawal in a twodimensional domain is simulated for two different geometries of the oil lens and for varied values of the physical parameters. Assuming vertical equilibrium, the oil flow equation is reduced by vertical integration. The well boundary condition is approximated by imposing zero oil lens thickness. Similarity solutions of the reduced equations for the two geometries show good agreement with the numerical results in most cases.