Strontium, oxygen, and hydrogen isotope geochemistry of hydrothermally altered and weathered rocks in DSDP Hole 504B, Costa Rica Rift

DSDP Hole 504B was drilled into 6 Ma crust, about 200 km south of the Costa Rica Rift, Galapagos Spreading Center, penetrating 1.35 km into a section that can be divided into four zones—Zone I: oxic submarine weathering; Zone II: anoxic alteration; Zones III and IV: hydrothermal alteration to greenschist facies. In Zone III there is intense veining of pillow basalts. Zone IV consists of altered sheeted dikes. Isotopic geochemical signatures in relation to the alteration zones are recorded in Hole 504B, as follows:

Zone	Depth(m)	Average87Sr/86Sr	Average δ18O (%o)	Average δD (%o)
I	275–550	0.7032	7.3	−63
II	550–890	0.7029	6.5	−45
III	890–1050	0.7035	5.6	−31
IV	1050–1350	0.7032	5.5	−36

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Alteration temperatures are as low as 10°C in Zones I and II based on oxygen isotope fractionation. Strontium isotopic data indicate that a circulation of seawater is much more restricted in Zone II than in Zone I. Fluid inclusion measurements of vein quartz indicate the alteration temperature was mainly 300 ± 20°C in Zones III and IV, which is consistent with secondary mineral assemblages.The strontium, oxygen, and hydrogen isotopic compositions of hydrothermal fluids which were responsible for the greenschist facies alteration in Zones III and IV are estimated to be 0.7037, 2‰, and 3‰, respectively. Strontium and oxygen isotope data indicate that completely altered portions of greenstones and vein minerals were in equilibrium with modified seawater under low water/rock ratios (in weight) of about 1.6. This value is close to that of the end-member hydrothermal fluids issuing at 21°N EPR.Basement rocks are not completely hydrothermally altered. About 32% of the greenstones in Zones III and IV have escaped alteration. Thus 1 g of fresh basalt including the 32% unaltered portion are required in order to make 1 g of end-member solution from fresh seawater in water-rock reactions.     

Elastic properties of garnet solid-solution series

The elastic constants of sixteen garnet specimens of wide variety in chemical composition are accurately determined by means of the rectangular parallelpiped resonance method. The dependence of the elastic properties on chemical composition is analyzed using the present data and those for seven garnets investigated by other authors. The property X_i of a garnet solid solution i is given by a linear addition law in terms of the mole fraction n_ij of component j; X_i = Σn_ijX_j where the X_j's are the properties of the end-members j (j = pyrope, almandine, spessartine, grossular and andradite). The X_j's are determined for density ρ, bulk modulus K, and shear moduli C_s = (C₁₁ ? C₁₂)/2 and C₄₄. No systematic deviation is observed from the linear addition law for the elastic moduli nor for other quantities such as the elastic wave velocities. The extrapolated elastic moduli (Mbar) of the end-members are:

     

6.

The system Mg₂SiO₄MgOH₂O at high pressures and temperatures — Possible hydrous magnesian silicates in the mantle transition zone     

S. Akimoto  M. Akaogi 《Physics of the Earth and Planetary Interiors》1980,23(4):268-275

The system Mg₂SiO₄MgOH₂O was investigated at pressures between 85 and 160 kbar and at temperatures between 750 and 1200°C. In runs for a gel with Mg/Si ratio of 3 and with 4.0 wt.-percent H₂O, a dense hydrous magnesian silicate, denoted phase B by Ringwood and Major, was found at pressures from about 100 kbar to at least 160 kbar in the whole temperature range studied. In the following table the crystallographic parameters and chemical formula of phase B, determined in this study, are compared with those of the other dense hydrous silicates in Mg₂SiO₄MgOH₂O.

	Almandine	Pyrope	Spessartine	Grossular	Andradite
$\text{K}$	1.779 ± 0.008	1.730 ± 0.009	1.742 ± 0.009	1.691 ± 0.008	1.379 ± 0.017
$\text{C}{}_{\mathrm{<mtext>s</mtext>}}$	0.981 ± 0.004	0.925 ± 0.004	0.964 ± 0.004	1.106 ± 0.004	0.979 ± 0.007
$\text{C}{}_{\mathrm{<mtext>44</mtext>}}$	0.958 ± 0.005	0.919 ± 0.005	0.937 ± 0.005	1.017 ± 0.006	0.827 ± 0.010

     

7.

RUNOFF AND EROSION STUDIES IN A MOUNTAINOUS TERRA-ROSSA REGION IN ISRAEL     

Ido SEGINER  Joseph MORIN  Ami SHACHORI 《水文科学杂志》2013,58(4):79-92

     

8.

Water vapor above 25 km altitude     

Zander  R. 《Pure and Applied Geophysics》1973,106(1):1346-1351

     

9.

Regional distribution and temporal trends of some contaminants in the water of the Baltic Sea     

Lutz Brügmann  Horst Gaul  Karl-Heinz Rohde  Udo Ziebarth 《Ocean Dynamics》1991,44(4):161-184

During a cruise on board RV Gauss in May/June 1988, joint investigations into organochlorine compounds, dissolved trace metals, petroleum hydrocarbons and basic hydrography were carried out at representative stations of the Baltic Monitoring Programme (BMP). The aim of the cruise was to study distribution patterns and — using previous data — to establish temporal trends if at all discernible.Each group of contaminants investigated showed specific characteristics, with differences even between compounds within the same group. The differences are due to:

Phase	Composition	Space group	Cell parameters				Density (g cm?3)
			$\text{a}$	$\text{b}$	$\text{c}$	β
			(Å)	(Å)	(Å)	(°)
Chondrodite	Mg5Si2O10H2	$\text{P2}{}_1\text{/c}$	7.914	4.752	10.350	108.71	3.06
Clinohumite	Mg9Si4O18H2	$\text{P2}{}_1\text{/c}$	13.695	4.747	10.284	100.64	3.14
Phase A	Mg7Si2O14H6	$\text{P6}{}_3$	7.860		9.573		2.96
Phase B	Mg23Si8O42H6	$\text{P2}{}_1\text{/c}$	10.600	14.098	10.092	104.05	3.32

–	- the partition of contaminants between dissolved and adsorbed form;
–	- the response to redox conditions;
–	- the influence of microbial decay, organic production or changes in speciation.

     

The system Mg2SiO4MgOH2O at high pressures and temperatures — Possible hydrous magnesian silicates in the mantle transition zone

The system Mg₂SiO₄MgOH₂O was investigated at pressures between 85 and 160 kbar and at temperatures between 750 and 1200°C. In runs for a gel with Mg/Si ratio of 3 and with 4.0 wt.-percent H₂O, a dense hydrous magnesian silicate, denoted phase B by Ringwood and Major, was found at pressures from about 100 kbar to at least 160 kbar in the whole temperature range studied. In the following table the crystallographic parameters and chemical formula of phase B, determined in this study, are compared with those of the other dense hydrous silicates in Mg₂SiO₄MgOH₂O.

Regional distribution and temporal trends of some contaminants in the water of the Baltic Sea

During a cruise on board RV Gauss in May/June 1988, joint investigations into organochlorine compounds, dissolved trace metals, petroleum hydrocarbons and basic hydrography were carried out at representative stations of the Baltic Monitoring Programme (BMP). The aim of the cruise was to study distribution patterns and — using previous data — to establish temporal trends if at all discernible.Each group of contaminants investigated showed specific characteristics, with differences even between compounds within the same group. The differences are due to:

Transformation of phosphorus species in settling seston and during early sediment diagenesis

Sequential P extraction was combined with electron microscop and X-ray spectroscopy to characterise various P species and to study their transformation in settling seston and in recent sediment. During early diagenesis most of the particulate P formed in the water was redissolved. No net transformation into species that would resist dissolution was observed.It was shown that

Outlier detection with partial information: application to emergency mapping

This paper, addresses the problem of novelty detection in the case that the observed data is a mixture of a known ‘background’ process contaminated with an unknown other process, which generates the outliers, or novel observations. The framework we describe here is quite general, employing univariate classification with incomplete information, based on knowledge of the distribution (the probability density function, pdf) of the data generated by the ‘background’ process. The relative proportion of this ‘background’ component (the prior ‘background’ probability), the pdf and the prior probabilities of all other components are all assumed unknown. The main contribution is a new classification scheme that identifies the maximum proportion of observed data following the known ‘background’ distribution. The method exploits the Kolmogorov–Smirnov test to estimate the proportions, and afterwards data are Bayes optimally separated. Results, demonstrated with synthetic data, show that this approach can produce more reliable results than a standard novelty detection scheme. The classification algorithm is then applied to the problem of identifying outliers in the SIC2004 data set, in order to detect the radioactive release simulated in the ‘joker’ data set. We propose this method as a reliable means of novelty detection in the emergency situation which can also be used to identify outliers prior to the application of a more general automatic mapping algorithm.

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A Multiple Criteria Decision Modelling approach to selection of estimation techniques for fitting extreme floods

The problem of fitting a probability distribution, here log-Pearson Type III distribution, to extreme floods is considered from the point of view of two numerical and three non-numerical criteria. The six techniques of fitting considered include classical techniques (maximum likelihood, moments of logarithms of flows) and new methods such as mixed moments and the generalized method of moments developed by two of the co-authors. The latter method consists of fitting the distribution using moments of different order, in particular the SAM method (Sundry Averages Method) uses the moments of order 0 (geometric mean), 1 (arithmetic mean), –1 (harmonic mean) and leads to a smaller variance of the parameters. The criteria used to select the method of parameter estimation are:

Geochemistry of water and gas discharges from the Mt. Amiata silicic complex and surrounding areas (central Italy)

The Mt. Amiata volcano in central Italy is intimately related to the post-orogenic magmatic activity which started in Pliocene times. Major, trace elements, and isotopic composition of thermal and cold spring waters and gas manifestations indicate the occurrence of three main reservoir of the thermal and cold waters in the Mt. Amiata region. The deepest one is located in an extensive carbonate reservoir buried by thick sequences of low-permeability allochthonous and neo-autochthonous formations. Thermal spring waters discharging from this aquifer have a neutral Ca-SO₄ composition due to the presence of anhydrite layers at the base of the carbonate series and, possibly, to absorption of deep-derived H₂S with subsequent oxidation to SO₄²⁻ in a system where pH is buffered by the calcite–anhydrite pair (Marini and Chiodini, 1994). Isotopic signature of these springs and N₂-rich composition of associated gas phases suggest a clear local meteoric origin of the feeding waters, and atmospheric O₂ may be responsible for the oxidation of H₂S. The two shallower aquifers have different chemical features. One is Ca-HCO₃ in composition and located in several sedimentary formations above the Mesozoic carbonates. The other one has a Na-Cl composition and is hosted in marine sediments filling many post-orogenic NW–SE-trending basins. Strontium, Ba, F, and Br contents have been used to group waters associated with each aquifer. Although circulating to some extent in the same carbonate reservoir, the deep geothermal fluids at Latera and Mt. Amiata and thermal springs discharging from their outcropping areas have different composition: Na-Cl and Ca-SO₄ type, respectively. Considering the high permeability of the reservoir rock, the meteoric origin of thermal springs and the two different composition of the thermal waters, self-sealed barriers must be present at the boundaries of the geothermal systems. The complex hydrology of the reservoir rocks greatly affects the reliability of geothermometers in liquid phase, which understimate the real temperatures of the discovered geothermal fields. More reliable temperatures are envisaged by using gas composition-based geothermometers. Bulk composition of the 67 gas samples studied seems to be the result of a continuous mixing between a N₂-rich component of meteoric origin related to the Ca-SO₄ aquifer and a deep CO₂-rich component rising largely along the boundaries of the geothermal systems. Nitrogen-rich gas samples have nearly atmospheric N₂/Ar (=83) and

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(δ=0‰) ratios whereas CO₂-rich samples show anomalously high

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values (up to +6.13 ‰), likely related to N₂ from metamorphic schists lying below the carbonate formations. On the basis of average

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isotopic ratio (

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around 0‰), CO₂ seems to originate mainly from thermometamorphic reactions in the carbonate reservoir and/or in carbonate layers embedded in the underlying metamorphic basement. Distribution of

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isotopic ratios indicates a radiogenic origin of helium in a tectonic environment that, in spite of the presence of many post-orogenic basins and mantle-derived magmatics, can presently be considered in a compressive phase.     

Derivation of Photosynthetically Available Radiation from METEOSAT data in the German Bight with Neural Nets

Two different models, a Physical Model and a Neural Net (NN), are used for the derivation of the Photosynthetically Available Radiation (PAR) from METEOSAT data in the German Bight; advantages and disadvantages of both models are discussed. The use of a NN for derivation of PAR should be preferred to the Physical Model because by construction, a NN can take the various processes determining PAR on a surface much better into account than a non-statistical model relying on averaged relations.

A model of producer incentives for livestock disease management

We examine the management of livestock diseases from the producers‘ perspective, incorporating information and incentive asymmetries between producers and regulators. Using a stochastic dynamic model, we examine responses to different policy options including indemnity payments, subsidies to report at-risk animals, monitoring, and regulatory approaches to decreasing infection risks when perverse incentives and multiple policies interact. This conceptual analysis illustrates the importance of designing efficient combinations of regulatory and incentive-based policies.

Spatial random field simulation by a numerical series representation

An approach to the simulation of spatial random fields is proposed. The target random field is specified by its covariance function which need not be homogeneous or Gaussian. The technique provided is based on an approximate Karhunen–Loève expansion of spatial random fields which can be readily realized. Such an approximate representation is obtained from a correction to the Rayleigh–Ritz method based on the dual Riesz basis theory. The resulting numerical projection procedure improves Rayleigh–Ritz algorithm in the approximation of second-order random fields. Simulations are developed to illustrate the convergence and accuracy of the method presented.

Viscosity of a Teide phonolite in the welding interval

The viscosity of a natural phonolitic composition with variable amounts of H₂O has been experimentally determined. The starting materials were crystal-free phonolitic glasses from Montaña Blanca, situated within the Las Cañadas caldera of Teide. Dry phonolitic melt viscosities were determined using concentric cylinder viscometry in the low viscosity range. The glassy quench products of these runs were then hydrated by high pressure synthesis in a piston–cylinder apparatus to generate a suite of samples with water contents ranging from 0.02 to 3.75 wt%. Samples thus hydrated were quenched rapidly and prepared (cut and polished) for the determination of water contents by infrared spectroscopy before and after experimental viscometry. The viscosities of the melts (dry and hydrated) were determined at 1 bar using a micropenetration technique. Samples were stable under the measurement conditions up to 3.75 wt% H₂O. Homogeneity of water content was confirmed by infrared spectroscopy and total water contents were calculated using absorptivity coefficients for compositions extremely close to that investigated here. The variation of viscosity as a function of water content and temperature can be described in the high viscosity interval of relevance to many welding processes by the non-Arrhenian expression:

(1)

log₁₀ η=−5.900−0.286 ln (H₂O)+(10775.4−394.8(H₂O))/(T−148.7+21.65 ln (H₂O))

whereas the high viscosity range alone is adequately described by the Arrhenian expression

(2)

log₁₀ η=−10.622−0.738 ln (H₂O)+(17114.3−590.4(H₂O))×1/T

where η is the viscosity in Pa s, H₂O is the water content in wt% and T is the temperature in K.These results are particularly useful for the scaling of conditions extant during the welding of phonolitic products of Montaña Blanca. The welding of glassy phonolitic rocks is enhanced by the lower viscosity of these melts with respect to calcalkaline rhyolites. The ratio of viscosities of phonolitic to calcalkaline rhyolitic melts is a complex function of temperature and water content and reaches up to 10^4.5 at 0.1 wt% H₂O and 500°C. Abundant evidence of welding and remobilisation of pyroclastic and spatter products of Teide system volcanism are consistent with these experimental observations.     

A note on common infections and the non-antibiotic treatment option

Recently, Batabyal and Nijkamp (Environ Econ Policy Stud 7:39–51, 2005) have used a theoretical model of antibiotic use to study the relative merits of interventionist (antibiotics) and non-interventionist (no antibiotics) treatment options. A key assumption in their paper is that the default treatment option is the interventionist option. Because there are several instances in which this assumption is invalid, in this paper, we suppose that the default treatment option is the non-interventionist option. Specifically, we first derive the long run average cost of treating a common infection such as acute otitis media (AOM). Next, we show that there is a particular tolerance level and that when a physician uses this tolerance level to determine when to administer the non-antibiotic medicine, the long run average cost of treating the common infection under study is minimized.

Saving lives in earthquakes: successes and failures in seismic protection since 1960

This paper will look at what we have and have not achieved in reducing the risks to human life from earthquakes in the last 50 years. It will review how success has been achieved in a few parts of the world, and consider what needs to be done by the scientific and engineering community globally to assist in the future task of bringing earthquake risks under control. The first part of the talk will re-examine what we know about the casualties from earthquakes in the last 50 years. Almost 80% of about 1 million deaths turn out to have been caused by just ten great earthquakes, together affecting a tiny proportion of the territory at risk from heavy ground shaking. The disparity between richer and poorer countries is also evident, not only in fatality rates, but also in their rates of change. But the existing casualty database turns out to be a very poor basis for observing such differences, not only because of the small number of lethal events, but also because of the very limited data on causes of death, types and causes of injury. These have been examined in detail in only a few, recent events. All that can be said with certainty is that a few wealthier earthquake-prone countries or regions have made impressive progress in reducing the risk of death from earthquakes, while most of the rest of the world has achieved comparatively little, and in some areas the problem has become much worse. The second part of the paper looks in more detail at what has been achieved country-by-country. Based on a new expert-group survey of key individuals involved in earthquake risk mitigation, it will examine what are perceived to be the successes and failures of risk mitigation in each country or group of countries. This survey will be used to highlight the achievements of those countries which have successfully tackled their earthquake risk; it will examine the processes of earthquake risk mitigation, from campaigning to retrofitting, and it will consider to what extent the achievement is the result of affluence, scientific and technical activity, political advocacy, public awareness, or the experience of destructive events. It will ask to what extent the approaches pioneered by the global leaders can be adopted by the rest. The final section of the talk will argue that it can be useful to view earthquake protection activity as a public health matter to be advanced in a manner similar to globally successful disease-control measures: it will be argued that the key components of such programmes—building in protection; harnessing new technology and creating a safety culture—must be the key components of earthquake protection strategies also. It will consider the contribution which the scientific and engineering community can make to bringing down today’s unacceptably high global earthquake risk. It will be suggested that this role is wider than commonly understood and needs to include: Building-in protection

Probabilistic risk analysis using ordered weighted averaging (OWA) operators

The concepts of system load and capacity are pivotal in risk analysis. The complexity in risk analysis increases when the input parameters are either stochastic (aleatory uncertainty) and/or missing (epistemic uncertainty). The aleatory and epistemic uncertainties related to input parameters are handled through simulation-based parametric and non-parametric probabilistic techniques. The complexities increase further when the empirical relationships are not strong enough to derive physical-based models. In this paper, ordered weighted averaging (OWA) operators are proposed to estimate the system load. The risk of failure is estimated by assuming normally distributed reliability index. The proposed methodology for risk analysis is illustrated using an example of nine-input parameters. Sensitivity analyses identified that the risk of failure is dominated by the attitude of a decision-maker to generate OWA weights, missing input parameters and system capacity.