Foreign inclusions in stony meteorites—III. Rare gases and oxygen isotopes in a carbonaceous chondritic xenolith in the Plainview gas-rich chondrite     

Laurel L. Wilkening  Robert N. Clayton 《Geochimica et cosmochimica acta》1974,38(6):937-945

Measurements of oxygen and rare gas isotopes in a carbonaceous xenolithic inclusion in the Plainview H5 chondrite indicate that the xenolith and Plainview host are of two distinct meteorite types, and that no isotopic exchange has taken place between the two materials since their juxtaposition. The oxygen isotope analysis of the xenolith yields δ-¹⁸O value of 6.5 ± 0.1 % relative to SMOW, a value similar to that of carbonaceous chondrites (C2). Rare gas contents of the xenolith are also similar to those of carbonaceous chondrites. The radiation ages of the xenolith ($\text{2.9 ± 0.4}\text{Myr}$) and the host ($\text{2.8 ± 0.4}\text{Myr}$) are identical.Analyses of the rare gases in a sample of the host material adjacent to the xenolith show that Plainview is gas-rich, i.e., it contains large amounts (52,300 ± 10^?8 cm³ STP/g ⁴He) of solar-type trapped gases.We speculate that carbonaceous chondritic material may be more prevalent in the asteroid belt than previously suspected.  相似文献   

A Methodology for Sensitivity Analysis Based on Regression: Applications to Handle Uncertainty in Natural Resources Characterization     

Yevgeniy Zagayevskiy  Clayton V. Deutsch 《Natural Resources Research》2015,24(3):239-274

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A Hybrid Estimation Technique Using Elliptical Radial Basis Neural Networks and Cokriging     

Samson  Matthew  Deutsch  Clayton V. 《Mathematical Geosciences》2022,54(3):573-591

Mathematical Geosciences - Mineral resource estimation is an integral part of making informed decisions while evaluating a mining operation’s feasibility. Geostatistical tools estimate...  相似文献   

Implementation of the Iterative Proportion Fitting Algorithm for Geostatistical Facies Modeling     

Yupeng Li  Clayton V. Deutsch 《Natural Resources Research》2012,21(2):221-231

In geostatistics, most stochastic algorithm for simulation of categorical variables such as facies or rock types require a conditional probability distribution. The multivariate probability distribution of all the grouped locations including the unsampled location permits calculation of the conditional probability directly based on its definition. In this article, the iterative proportion fitting (IPF) algorithm is implemented to infer this multivariate probability. Using the IPF algorithm, the multivariate probability is obtained by iterative modification to an initial estimated multivariate probability using lower order bivariate probabilities as constraints. The imposed bivariate marginal probabilities are inferred from profiles along drill holes or wells. In the IPF process, a sparse matrix is used to calculate the marginal probabilities from the multivariate probability, which makes the iterative fitting more tractable and practical. This algorithm can be extended to higher order marginal probability constraints as used in multiple point statistics. The theoretical framework is developed and illustrated with estimation and simulation example.  相似文献   

Two Artifacts of Probability Field Simulation   总被引：1，自引：0，他引：1  

Michael J. Pyrcz  Clayton V. Deutsch 《Mathematical Geology》2001,33(7):775-799

Probability field simulation is being used increasingly to simulate geostatistical realizations. The method can be faster than conventional simulation algorithms and it is well suited to integrate prior soft information in the form of local probability distributions. The theoretical basis of probability field simulation has been established when there are no conditioning data; however, no such basis has been established in presence of conditioning data. Realizations generated by probability field simulation show two severe artifacts near conditioning data. We document these artifacts and show theoretically why they exist. The two artifacts that have been investigated are (1) local conditioning data appear as local minima or maxima of the simulated values, and (2) the variogram model in range of conditioning data is not honored; the simulated values have significantly greater continuity than they are supposed to. These two artifacts are predicted by theory. An example flow simulation study is presented to illustrate that they affect more than the visual appearance of the simulated realizations. Notwithstanding the flexibility of the probability field simulation method, these two artifacts suggest that it be used with caution in presence of conditioning data. Future research may overcome these limitations.  相似文献   

Kriging with strings of data   总被引：1，自引：0，他引：1  

Clayton V. Deutsch 《Mathematical Geology》1994,26(5):623-638

The concept of a random function and, consequently, the application of kriging cells for the implicit assumption that the data locations are embedded within an infinite domain. An implication of this assumption is that, all else being equal, outlying data locations will receive greater weight because they are seen as less redundant, hence, more informative of the infinite domain. A two- step kriging procedure is proposed for correcting this siring effect. The first step is to establish the total kriging weight attributable to each string. The distribution of that total weight to the samples in the string is accomplished by a second stage of kriging. In the second stage, a spatial redundancy measure r_(n) is used in place of the covariance measure in the data-data kriging matrix. This measure is constructed such that each datum has the same redundancy with the (n)data of the string to which it belongs. This paper documents the problem of kriging with strings of data, develops the redundancy measure r_(n),and presents a number of examples.  相似文献   

Cristobalite-pyroxene in an L6 chondrite: implications for metamorphism     

Edward J. Olsen  Toshiko K. Mayeda  Robert N. Clayton 《Earth and Planetary Science Letters》1981

CRISPY is a cristobalite-pyroxene assemblage in the L6 chondrite ALHA 76003. It was formed by reaction of a very siliceous inclusion with the surrounding olivine-rich rock. Oxygen isotopes show that the inclusion was derived from a source with non-chondritic isotopic composition. The isotopes also show that the oxygen of the pyroxene reaction product was derived by simple mixing of oxygen from the inclusion and its immediately adjacent surroundings, with exchange with the bulk meteorite limited to a distance of about a millimeter. The persistence of cristobalite in close proximity to olivine, and the lack of isotopic equilibration, show that the metamorphic processes that form petrographic grade 6 chondrites involve transport of major elements over distances only on the order of millimeters.  相似文献   

Cosmoradiogenic ghosts and the origin of Ca-Al-rich inclusions     

Donald D. Clayton 《Earth and Planetary Science Letters》1977,35(3):398-410

The Ca-Al-rich inclusions within Allende are described as quickly frozen non-equilibrated partial melts arising from energetic collisions between centimeter-sized mechanical accumulations of cold presolar grains. The resulting minerals are refractory-rich because refractory supernova condensates are the most persistent components of the preheated accumulates. The shock heating drives off most of the more volatile matrix that had accumulated cold around the refractory cores, which quickly recrystallize while picking up isotopically homogenized trace elements. This picture is advanced to account for the isotopic anomalies in those elements for which fractionation of stardust from gas also fractionates a special isotope whose stellar condensation history can be expected to have been special.I call the anomaly that would have existed before the special component was added anisotopic ghost. These ghosts can be larger than the special anomaly surviving today in meteorites and planets. I argue that ghosts in²⁶Mg/²⁴Mg,⁸⁷Sr/⁸⁶Sr, and^206,207Pb/²⁰⁴Pb have caused erroneous cosmoradiogenic estimates of large age differences between meteorites, their special phases, and even the Moon.  相似文献   

Chemical and isotopic fractionation by grain size separates     

Donald D. Clayton 《Earth and Planetary Science Letters》1980,47(2):199-210

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Acceptance speech for the V. M. Goldschmidt Medal     

Robert N. Clayton 《Geochimica et cosmochimica acta》1982,46(6):1134-1135

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