9,892 research outputs found
Palladium, platinum, and gold distribution in serpentinite seamounts in the Mariana and Izu-Bonin forearcs: evidence from Leg 125 fluids and serpentinites
Palladium, platinum, and gold were analyzed for 20 interstitial water samples from Leg 125. No Pd or Pt was detected in fluids from serpentinite muds from Conical Seamount in the Mariana forearc, indicating that low-temperature seawater-peridotite interaction does not mobilize these elements into the serpentinizing fluids to levels above 0.10 parts per billion (ppb) in solution. However, Au may be mobilized in high pH solutions. In contrast, fluids from vitric-rich clays on the flanks of the Torishima Seamount in the Izu-Bonin forearc have Pd values of between 4.0 and 11.8 nmol/L, Pt values between 2.3 and 5.0 nmol/L and Au values between 126.9 and 1116.9 pmol/L. The precious metals are mobilized, and possibly adsorbed onto clay mineral surfaces, during diagenesis and burial of the volcanic-rich clays. Desorption during squeezing of the sediments may produce the enhanced precious metal concentrations in the analyzed fluids. The metals are mobilized in the fluids probably as neutral hydroxide, bisulfide, and ammonia complexes. Pt/Pd ratios are between 0.42 and 2.33, which is much lower than many of the potential sources for Pt and Pd but is consistent with the greater solubility of Pd compared with Pt in most natural low-temperature fluids
Palladium, platinum, and gold distribution in serpentinite seamounts in the Mariana and Izu-Bonin forearcs: evidence from Leg 125 fluids and serpentinites
Palladium, platinum, and gold were analyzed for 20 interstitial water samples from Leg 125. No Pd or Pt was detected in fluids from serpentinite muds from Conical Seamount in the Mariana forearc, indicating that low-temperature seawater-peridotite interaction does not mobilize these elements into the serpentinizing fluids to levels above 0.10 parts per billion (ppb) in solution. However, Au may be mobilized in high pH solutions. In contrast, fluids from vitric-rich clays on the flanks of the Torishima Seamount in the Izu-Bonin forearc have Pd values of between 4.0 and 11.8 nmol/L, Pt values between 2.3 and 5.0 nmol/L and Au values between 126.9 and 1116.9 pmol/L. The precious metals are mobilized, and possibly adsorbed onto clay mineral surfaces, during diagenesis and burial of the volcanic-rich clays. Desorption during squeezing of the sediments may produce the enhanced precious metal concentrations in the analyzed fluids. The metals are mobilized in the fluids probably as neutral hydroxide, bisulfide, and ammonia complexes. Pt/Pd ratios are between 0.42 and 2.33, which is much lower than many of the potential sources for Pt and Pd but is consistent with the greater solubility of Pd compared with Pt in most natural low-temperature fluids
Integrals of Motion for Critical Dense Polymers and Symplectic Fermions
We consider critical dense polymers . We obtain for this model
the eigenvalues of the local integrals of motion of the underlying Conformal
Field Theory by means of Thermodynamic Bethe Ansatz. We give a detailed
description of the relation between this model and Symplectic Fermions
including the indecomposable structure of the transfer matrix. Integrals of
motion are defined directly on the lattice in terms of the Temperley Lieb
Algebra and their eigenvalues are obtained and expressed as an infinite sum of
the eigenvalues of the continuum integrals of motion. An elegant decomposition
of the transfer matrix in terms of a finite number of lattice integrals of
motion is obtained thus providing a reason for their introduction.Comment: 53 pages, version accepted for publishing on JSTA
Trace element geochemistry of peridotites from the Izu-Bonin-Mariana Forearc, Leg 125
Trace element analyses (first-series transition elements, Ti, Rb, Sr, Zr, Y, Nb, and REE) were carried out on whole rocks and minerals from 10 peridotite samples from both Conical Seamount in the Mariana forearc and Torishima Forearc Seamount in the Izu-Bonin forearc using a combination of XRF, ID-MS, ICP-MS, and ion microprobe. The concentrations of incompatible trace elements are generally low, reflecting the highly residual nature of the peridotites and their low clinopyroxene content (n ratios in the range of 0.05-0.25; several samples show possible small positive Eu anomalies. LREE enrichment is common to both seamounts, although the peridotites from Conical Seamount have higher (La/Ce)n ratios on extended chondrite-normalized plots, in which both REEs and other trace elements are organized according to their incompatibility with respect to a harzburgitic mantle. Comparison with abyssal peridotite patterns suggests that the LREEs, Rb, Nb, Sr, Sm, and Eu are all enriched in the Leg 125 peridotites, but Ti and the HREEs exhibit no obvious enrichment. The peridotites also give positive anomalies for Zr and Sr relative to their neighboring REEs. Covariation diagrams based on clinopyroxene data show that Ti and the HREEs plot on an extension of an abyssal peridotite trend to more residual compositions. However, the LREEs, Rb, Sr, Sm, and Eu are displaced off this trend toward higher values, suggesting that these elements were introduced during an enrichment event. The axis of dispersion on these plots further suggests that enrichment took place during or after melting and thus was not a characteristic of the lithosphere before subduction.
Compared with boninites sampled from the Izu-Bonin-Mariana forearc, the peridotites are significantly more enriched in LREEs. Modeling of the melting process indicates that if they represent the most depleted residues of the melting events that generated forearc boninites they must have experienced subsolidus enrichment in these elements, as well as in Rb, Sr, Zr, Nb, Sm, and Eu. The lack of any correlation with the degree of serpentinization suggests that low-temperature fluids were not the prime cause of enrichment. The enrichment in the high-field-strength elements also suggests that at least some of this enrichment may have involved melts rather than aqueous fluids. Moreover, the presence of the hydrous minerals magnesio-hornblende and tremolite and the common resorption of orthopyroxene indicate that this high-temperature peridotite-fluid interaction may have taken place in a water-rich environment in the forearc following the melting event that produced the boninites. The peridotites from Leg 125 may therefore contain a record of an important flux of elements into the mantle wedge during the initial formation of forearc lithosphere. Ophiolitic peridotites with these characteristics have not yet been reported, perhaps because the precise equivalents to the serpentinite seamounts have not been analyzed
Off-Critical Logarithmic Minimal Models
We consider the integrable minimal models , corresponding
to the perturbation off-criticality, in the {\it logarithmic
limit\,} , where are coprime and the
limit is taken through coprime values of . We view these off-critical
minimal models as the continuum scaling limit of the
Forrester-Baxter Restricted Solid-On-Solid (RSOS) models on the square lattice.
Applying Corner Transfer Matrices to the Forrester-Baxter RSOS models in Regime
III, we argue that taking first the thermodynamic limit and second the {\it
logarithmic limit\,} yields off-critical logarithmic minimal models corresponding to the perturbation of the critical
logarithmic minimal models . Specifically, in accord with the
Kyoto correspondence principle, we show that the logarithmic limit of the
one-dimensional configurational sums yields finitized quasi-rational characters
of the Kac representations of the critical logarithmic minimal models . We also calculate the logarithmic limit of certain off-critical
observables related to One Point Functions and show that the
associated critical exponents
produce all conformal dimensions in the infinitely extended Kac table. The corresponding Kac labels
satisfy . The exponent is obtained from the logarithmic limit of the free energy giving the
conformal dimension for the perturbing field . As befits a non-unitary
theory, some observables diverge at criticality.Comment: 18 pages, 5 figures; version 3 contains amplifications and minor
typographical correction
Heating of the Intracluster Gas in the Triangulum Australis Cluster
ASCA and ROSAT X-ray data are used to obtain two-dimensional maps of the gas
temperature, pressure and specific entropy in the Triangulum Australis cluster
of galaxies. We find that this hot (T_e=10.3+-0.8 keV) system probably has a
temperature peak (T_e>12 keV) at the cluster core, which approximately
corresponds to the adiabatic relation. An underdense gas sector, found in the
ROSAT cluster image eastward of the core, has a higher temperature than average
at that radius. At this higher temperature, the gas pressure in this region is
equal to that of the rest of the cluster at the same radius, but the specific
entropy of this gas is significantly higher (although the temperature
difference itself is only marginally significant). We speculate that the
existence of this region of underdense high-entropy gas, as well as the
adiabatic central temperature peak, indicate recent or ongoing heating of the
intergalactic medium in this cluster. The most probable source of such heating
is a subcluster merger, for which the hydrodynamic simulations predict a
qualitatively similar temperature structure. We point out that entropy maps can
provide a physically meaningful way of diagnosing merging clusters and
comparing the predictions of merger simulations to the data.Comment: Text revised to give more technical details and clarify discussion.
Accepted for ApJ Letters. Latex, 5 pages incl. figures, macros include
W-Extended Fusion Algebra of Critical Percolation
Two-dimensional critical percolation is the member LM(2,3) of the infinite
series of Yang-Baxter integrable logarithmic minimal models LM(p,p'). We
consider the continuum scaling limit of this lattice model as a `rational'
logarithmic conformal field theory with extended W=W_{2,3} symmetry and use a
lattice approach on a strip to study the fundamental fusion rules in this
extended picture. We find that the representation content of the ensuing closed
fusion algebra contains 26 W-indecomposable representations with 8 rank-1
representations, 14 rank-2 representations and 4 rank-3 representations. We
identify these representations with suitable limits of Yang-Baxter integrable
boundary conditions on the lattice and obtain their associated W-extended
characters. The latter decompose as finite non-negative sums of W-irreducible
characters of which 13 are required. Implementation of fusion on the lattice
allows us to read off the fusion rules governing the fusion algebra of the 26
representations and to construct an explicit Cayley table. The closure of these
representations among themselves under fusion is remarkable confirmation of the
proposed extended symmetry.Comment: 30 page
Boundary operators in the O(n) and RSOS matrix models
We study the new boundary condition of the O(n) model proposed by Jacobsen
and Saleur using the matrix model. The spectrum of boundary operators and their
conformal weights are obtained by solving the loop equations. Using the
diagrammatic expansion of the matrix model as well as the loop equations, we
make an explicit correspondence between the new boundary condition of the O(n)
model and the "alternating height" boundary conditions in RSOS model.Comment: 29 pages, 4 figures; version to appear in JHE
Solvable Critical Dense Polymers
A lattice model of critical dense polymers is solved exactly for finite
strips. The model is the first member of the principal series of the recently
introduced logarithmic minimal models. The key to the solution is a functional
equation in the form of an inversion identity satisfied by the commuting
double-row transfer matrices. This is established directly in the planar
Temperley-Lieb algebra and holds independently of the space of link states on
which the transfer matrices act. Different sectors are obtained by acting on
link states with s-1 defects where s=1,2,3,... is an extended Kac label. The
bulk and boundary free energies and finite-size corrections are obtained from
the Euler-Maclaurin formula. The eigenvalues of the transfer matrix are
classified by the physical combinatorics of the patterns of zeros in the
complex spectral-parameter plane. This yields a selection rule for the
physically relevant solutions to the inversion identity and explicit finitized
characters for the associated quasi-rational representations. In particular, in
the scaling limit, we confirm the central charge c=-2 and conformal weights
Delta_s=((2-s)^2-1)/8 for s=1,2,3,.... We also discuss a diagrammatic
implementation of fusion and show with examples how indecomposable
representations arise. We examine the structure of these representations and
present a conjecture for the general fusion rules within our framework.Comment: 35 pages, v2: comments and references adde
A Merger Scenario for the Dynamics of Abell 665
We present new redshift measurements for 55 galaxies in the vicinity of the
rich galaxy cluster Abell 665. When combined with results from the literature,
we have good velocity measurements for a sample of 77 confirmed cluster members
from which we derive the cluster's redshift z=0.1829 +/- 0.0005 and
line-of-sight velocity dispersion of 1390 +/- 120 km/s. Our analysis of the
kinematical and spatial data for the subset of galaxies located within the
central 750 kpc reveals only subtle evidence for substructure and
non-Gaussianity in the velocity distribution. We find that the brightest
cluster member is not moving significantly relative to the other galaxies near
the center of the cluster. On the other hand, our deep ROSAT high resolution
image of A665 shows strong evidence for isophotal twisting and centroid
variation, thereby confirming previous suggestions of significant substructure
in the hot X-ray--emitting intracluster gas. In light of this evident
substructure, we have compared the optical velocity data with N-body
simulations of head-on cluster mergers. We find that a merger of two similar
mass subclusters (mass ratios of 1:1 or 1:2) seen close to the time of
core-crossing produces velocity distributions that are consistent with that
observed.Comment: 30 pages and 7 figures. Accepted by the Astrophysical Journal Full
resoultion figures 1 and 3 available in postscript at
http://www.physics.rutgers.edu/~percy/A665paper.htm
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