A method of estimating the periodic constituent of a geophysical series

Summary Small temperature variations of hot springs, having an apparent period length of one year, had to be examined as to their reality. A method was introduced by which the periodic constituent of a series could be determined that consisted of twelve numerical values and was prevalently subject to an oscillation of the length of a whole year. The periodic component, surprisingly, proved to be quasi-constant for series of various geophysical elements with an undoubtedly real annual (daily) variation. The average periodic portion of the annual (daily) variation of twelve different geophysical elements amounted to 69%±2.5%.Only one element has thus far been found, variations of which had a much greater periodic constituent, viz. the annual temperature variation at places with a high continentality; there, the average periodic part was 91%±1.8%. Thus, a gap of 22% exists between these two cluster-points of periodic constituents.The method, applied to the annual temperature variations of nine hot springs, leads to a division of the springs into two groups. One group with a periodic constituentbelow 60% (average=44%), the other group with a periodic constituentabove 60% (average 69%). A comparison with the real variation of other geophysical elements indicates that the latter group shows a real annual variation of temperature, the former does not. Since the average temperatures of the springs are known from another geophysical investigation, it can be stated that the average temperature of the group with a large periodic component is, on the average, 10°F cooler than that of the other. The group with areal annual temperature variation has a higher source level. These geophysical relations were revealed by the present method.

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Zusammenfassung Kleine Temperaturvariationen heißer Quellen von der anscheinenden Länge eines Jahres sollten auf ihre Realität geprüft werden. Es wurde eine Methode benutzt, die erlaubte, den periodischen Gehalt von Reihen zu berechnen, die aus den Zahlenwerten von zwölf äquidistanten Ordinaten bestehen und vorzüglich einer Ganzjahresschwankung unterworfen sind. Diese Methode, angewendet auf verschiedene geophysikalische Reihen mit zweifellos realem Jahres- (Tages-) Gang, zeigte überraschenderweise, daß der periodische Gehalt dieser geophysikalischen Reihenquasi-konstant zu sein scheint. Der mittlere periodische Gehalt der Jahres-(Tages-) Schwankung von zwölf verschiedenen geophysikalischen Elementen war 69%±2,5%. Nurein Element konnte bisher gefunden werden, dessen periodischer Gehalt bedeutend größer war, und zwar derJahresgang der Temperatur an kontinental gelegenen Orten. Sein periodischer Gehalt beträgt 91%±1,8%. Zwischen den beiden Häufungsstellen des periodischen Gehaltes existiert so eine Lücke von 22%.Wenn man die Methode auf den Jahresgang der Temperaturen von neun heißen Quellen anwendet, kommt man zu einer Einteilung der Quellen in zwei Gruppen. Die eine hatte einen periodischen Gehaltunter 60% (Mittel=44%), die andere einenüber 60% (Mittel 69%). Der Vergleich mit den realen Gängen anderer geophysikalischer Elemente führte zu der Feststellung, daß die letztere Gruppe einenrealen Temperaturgang aufweist, was bei der ersteren Gruppenicht der Fall ist.Aus einer anderen geophysikalischen Untersuchung sind die mittleren Temperaturen der Quellen bekannt. So kann nun festgestellt werden, daß die Gruppe mit hohem periodischem Gehalt im Mittel um 10°F kühler ist als die andere. Die Gruppe mitreeller Jahresschwankung der Temperatur hat ein höheres Quellniveau. Diese geophysikalischen Beziehungen konnten durch die dargelegte Methode aufgedeckt werden.Résumé Il s'agissait de prouver la réalité de faibles variations de température de sources chaudes, variations à période apparemment annuelle. On a utilisé une méthode permettant de calculer la part périodique de séries obtenues à partir de valeurs numériques de 12 ordonnées équidistantes et présentant particulièrement une période annuelle. Cette méthode appliquée à différentes séries d'observations géophysiques à périodicité indiscutable (annuelle ou diurne) a révélé d'une façon surprenante que la part périodique de ces séries semble êtrequasi-constante. La part périodique moyenne de la variation annuelle (ou diurne) de 12 grandeurs géophysiques différentes était de 69%±2,5%. On n'a trouvé qu'un seul élément dont la part périodique était nettement plus grande, savoirla marche annuelle de la température de lieux à situation continentale; la part périodique était dans ce cas de 91%±1,8%. Entre les deux points de fréquence maximum de la part périodique il y a donc un intervalle de 22%.Appliquant la méthode à la marche annuelle de la température de 9 sources chaudes, on aboutit à un classement de ces sources en deux groupes. L'un présente une part périodiqueinférieure à 60% (moyenne 44%), l'autresupérieure à 60% (moyenne 69%). La comparaison avec la marche réelle d'autres grandeurs a conduit à la conclusion que le dernier groupe présente une variation de températureréelle, ce qui n'est pas le cas pour le premier. Grâce à une autre recherche géophysique, on connaît les températures moyennes des sources. On peut donc constater que le groupe dont la part périodique est grande est en moyenne de 10°F plus froide que l'autre. Le groupe à variation annuelleréelle de la température présente un niveau de source plus élevé. La méthode exposée a permis de découvrir ces relations géophysiques.

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With 4 Figures.     

Modeling the kinetics of silica nanocolloid formation and precipitation in geologically relevant aqueous solutions

The kinetics of the formation and precipitation of nanocolloidal silica from geologically relevant aqueous solutions is investigated. Changes in monomeric (SiO_2(mono)), nanocolloidal (SiO_2(nano)) and precipitated silica (SiO_2(ppt)) concentrations in aqueous solutions from pH 3 to 7, ionic strengths (IS) of 0.01 and 0.24 molal, and initial SiO₂ concentrations of 20.8, 12.5 and 4.2 mmolal (reported in [Icopini, G.A., Brantley, S.L., Heaney, P.J., 2005. Kinetics of silica oligomerization and nanocolloid formation as a function of pH and ionic strength at 25 °C. Geochim. Cosmochim. Acta69(2), 293-303.]) were fit using two kinetic models. The first model, termed the concentration model, is taken from Icopini et al. (2005) and assumes that the rate of change of SiO_2(mono) as a function of time has a fourth-order dependence on the concentration of SiO_2(mono) in solution. The second model, termed the supersaturation model, incorporates the equilibrium concentration of amorphous silica and predicts that polymerization will be a function of the degree of silica supersaturation in solution with respect to amorphous silica. While both models generally predicted similar rate constants for a given set of experimental conditions, the supersaturation model described the long-term equilibrium behavior of the SiO_2(mono) fraction more accurately, resulting in significantly better fits of the monomeric data. No difference was seen between the model fits of the nanocolloidal silica fraction. At lower pH values (3-4), a metastable equilibrium was observed between SiO_2(mono) and SiO_2(nano). This equilibrium SiO_2(mono) concentration was found to be 6 mmolal, or three times the reported solubility of bulk amorphous silica under the experimental conditions studied and corresponds to the predicted solubility of amorphous silica colloids approximately 3 nm in diameter. Atomic force microscopy was used to determine the average size of the primary nanocolloidal particles to be ∼3 nm, which is in direct agreement with the solubility calculations. Larger aggregates of the primary nanocolloids were also observed to range in size from 30 to 40 nm. This work provides the first kinetic models describing the formation and evolution of nanocolloidal silica in environmentally relevant aqueous solutions. Results indicate that nanocolloidal silica is an important species at low pH and neutral pH at low ionic strengths and may play a more important role in geochemical cycles in natural aqueous systems than previously considered.     

Petrology and mass-balance constraints on major-, trace-, and rare-earth-element mobility in porphyry-greisen alteration associated with the epizonal True Hill granite, southwestern New Brunswick, Canada

Endogreisen and exogreisen weakly mineralized with Bi, Sn, and Mo are associated with two of three granite porphyry (granite) cupolas hosted in Silurian metasedimentary rocks at True Hill, southwestern New Brunswick. The epizonal, weakly peraluminous and compositionally evolved True Hill granite is quartz and K-feldspar porphyritic; groundmass textures, such as granophyric patches, miarolitic cavities, and pegmatite pods, are indicative of rapid cooling and vapor saturation.The greisen mineralization in cupolas B and C is overprinted by various types of alteration, reflecting multi-stage devolatilization of the magma. The most intense topaz-bearing greisen is confined mainly to the apical parts of the granite. In places, fluorite is associated with silicification, sericitization, and chloritization, which is common to greisen-type alteration. The alteration types reflect the physical and chemical changes in the hydrothermal fluid that was derived principally by second boiling of the magma. Al-normalized, mass-balanced geochemical data supported by petrographic observations show that in the greisenized True Hill granite, Fe, Mn and Mg enrichment corresponds to chlorite and/or Fe-muscovite alteration and are coincident with leaching of Na and K and deposition of SiO₂. Ca was remobilized in the greisen environment, but erratically deposited as fluorite. Minor P and LREE enrichment are reflected by the presence of monazite in the greisen. The HFSE are mobile to a minor degree, based on correlations with elements known to be hydrothermally mobile. The base metals correlate with S and other ore-forming elements. The distribution of many of the trace elements is related to alteration, including the leaching of alkalis, which leads to the stabilization of aluminosilicates, principally muscovite and topaz. The distribution of trace elements reflects their relative mobility during greisenization, with high-field-strength elements (Zr and Ti) the most immobile and the lithophile and chalcophile elements the most mobile. Breccias and greisen alteration in cupola C at True Hill are similar to those at the base of the W-Mo-Bi porphyry-greisen in the Fire Tower zone above the Mount Pleasant fine-grained granite.     

New Jurassic Pseudopolycentropodids from China (Insecta: Mecoptera)

Abstract: In this paper two new species of fossil Pseudopolycentropus Handlirsch, 1906 are described: Pseudopolycentropus janeannae sp. nov. and P. novokshonovi, sp. nov. All of them were recovered from the Middle Jurassic non-marine sedimentary strata of northeastern China. The new material from China reveals that the early diversification of pseudopolycentropodids was well underway by the Middle Jurassic.     

Flux between soil and atmosphere, vertical concentration profiles in soil, and turnover of nitric oxide: 1. Measurements on a model soil core

A stainless steel soil corer which was filled with homogenized soil was used to measure the flux (J) of NO between soil and atmosphere and the vertical profile of the NO mixing ratios (m) in the soil atmosphere, both as function of the NO mixing ratio (mm _a ) in the atmosphere of the headspace. The NO emission flux decreased linearly with increasing NO mixing ratio and turned into a deposition flux after passage of the compensation point (m _c) at about 400 ppbv NO. Almost the same compensation point was obtained when the turnover of NO was measured in flask-incubated soil samples as function of the NO mixing ratio. The flux (J) of NO at the soil-atmosphere interface was calculated from the production rate (P) of NO and the NO uptake rate constant (k) that were measured in these flask-incubated soil samples using the diffusion model of Galbally and Johansson (1989). The calculated fluxes agreed within <15% with those actually measured. The vertical profiles of NO were fitted to an exponential function and analyzed by Fick's first law of diffusion. The shape of the profiles indicated a net production of NO in the upper 10 cm soil layer when the atmospheric NO mixing ratio was below the compensation point and in a net consumption of NO when the atmospheric NO mixing ratio was above the compensation point. In soil layers below 10 cm depth, the turnover of NO resulted in compensation of production and consumption rates. Measurement of the actual diffusion coefficient using SF₆ showed that gas transport in the soil core was not only due to molecular diffusion but in addition due to a bidirectional gas flow. The experimentally determined diffusion coefficient was smaller than that computed from soil porosities, but resulted together with the additional transport term in NO fluxes that were close (< ±15%) to those measured. This is the first comprehensive study of NO concentration profiles and turnover rates in soil providing a theoretical basis for modelling NO fluxes at the soil-atmosphere interface.     

Fluids during diagenesis and sulfate vein formation in sediments at Gale crater,Mars

We model the fluids involved in the alteration processes recorded in the Sheepbed Member mudstones of Yellowknife Bay (YKB), Gale crater, Mars, as revealed by the Mars Science Laboratory Curiosity rover investigations. We compare the Gale crater waters with fluids modeled for shergottites, nakhlites, and the ancient meteorite ALH 84001, as well as rocks analyzed by the Mars Exploration rovers, and with terrestrial ground and surface waters. The aqueous solution present during sediment alteration associated with phyllosilicate formation at Gale was high in Na, K, and Si; had low Mg, Fe, and Al concentrations—relative to terrestrial groundwaters such as the Deccan Traps and other modeled Mars fluids; and had near neutral to alkaline pH. Ca and S species were present in the 10^?3 to 10^?2 concentration range. A fluid local to Gale crater strata produced the alteration products observed by Curiosity and subsequent evaporation of this groundwater‐type fluid formed impure sulfate‐ and silica‐rich deposits—veins or horizons. In a second, separate stage of alteration, partial dissolution of this sulfate‐rich layer in Yellowknife Bay, or beyond, led to the pure sulfate veins observed in YKB. This scenario is analogous to similar processes identified at a terrestrial site in Triassic sediments with gypsum veins of the Mercia Mudstone Group in Watchet Bay, UK.     

Fractionation of stable carbon isotopes during anaerobic production and degradation of propionate in defined microbial cultures

In many anoxic environments propionate is, after acetate, the second most important fermentation product, being degraded further to finally result in CH₄ production. In principle, isotope discrimination can be used to assess the path of organic matter degradation to acetate, CO₂ and CH₄. However, nothing is known about the isotope fractionation in primary and secondary fermentation steps involving propionate, although it is an important precursor of acetate. We therefore studied the degradation of propionate with a syntrophic coculture of Syntrophobacter fumaroxidans and Methanobacterium formicicum. The isotope enrichment factor for propionate degradation to acetate, CO₂ and CH₄ was almost negligible (ε_prop 0.9‰). The fermentative production of propionate was studied in cultures with Opitutus terrae growing on pectin, xylan and starch. These polysaccharides were fermented to acetate, succinate, propionate, H₂ and CO₂. While the δ¹³C value of the initially produced propionate was similar to that of the organic substrates (ca. −28 to −25‰), the δ¹³C value of the other fermentation products was higher. The δ¹³C values of all products generally decreased during the course of fermentation. Finally, a small depletion in ¹³C (ca. 6‰) with respect to the organic substrate was observed for propionate, while the other fermentation products where slightly enriched. Overall, stable carbon isotope discrimination was small during both fermentative production and consumption of propionate in the anaerobic microbial cultures, so that propionate turnover probably only marginally affects isotope fractionation during anaerobic degradation of organic matter.     

Late Silurian–Middle Devonian long-term shoreline shifts on the northern Gondwanan margin: eustatic versus tectonic controls

Long-term shoreline shifts reflect eustatic changes, tectonic activity, and sediment supply. Available lithostratigraphical data from northern Africa, Arabia, and the Tethys Hymalaya, coupled with facies interpretations, permit us to trace late Silurian–Middle Devonian long-term shoreline shifts across the northern Gondwanan margin and to compare them with constraints on global sea-level changes. Our analysis establishes a regression–transgression cycle. Its coincident global sea-level changes reveal the dominance of the eustatic control. A transgression–regression cycle observed in Arabia is best explained by regional subsidence. Our study highlights the importance of constraining the role of regional tectonics when interpreting shoreline shifts.     

三角形形状因子对地壳形变计算精度的影响

引入三角形内切圆半径与外接圆半径之比值作为三角形形状因子，讨论利用三角形法计算应变分量的精度与三角形形状因子之间的关系。设计一种涵盖所有三角形形状的方法，计算分析了用三角形法计算应变分量精度的分布。研究表明：当三角形形状因子达到0．36时，计算得到的应变分量均方差，一般不会超过位移数据均方差的3倍；而当三角形形状因子小于0．1时，计算得到的应变分量均方差会陡然增大，这样的三角形一般不适合用于应变分量的计算。在利用GPS观测站组成三角形计算地应变时，建议所组成的三角形形状因子的阈值应取为0．1～0．36。     

Quantifying the effect of humic matter on the emission of mercury from artificial soil surfaces

A set of surface samples was created using purified laboratory grade sand treated with 0.05 μg/g Hg as the HgCl₂ salt and various concentrations of purified humic and fulvic acids. Emissions of elemental Hg from these substrates to the atmosphere were inversely correlated with the organic content of the samples (99% confidence level). The greatest differences in Hg emissions were found between samples containing the lowest concentrations of humic matter (0% versus 0.01% humic, and 0.01% versus 0.1% humic), only small differences in Hg flux were found to exist for samples with higher concentrations of humic acid (1%, 5%, and 100%). This effect was independent of the type of humic substance used, with both humic and fulvic acids showing an inhibitory effect on surface Hg emissions.