Terrestrial nickel-iron from the Josephine Peridotite,its geologic occurrence,associations, and origin     

Henry J.B. Dick 《Earth and Planetary Science Letters》1974,24(2):291-298

The distribution of placers containing coarse nuggets of the nickel-iron alloy, josephinite, are found to have a close spatial relationship to a narrow zone of intense shearing, serpentinization, and igneous intrusion within the Josephine Peridotite. These field relations, together with the frequent occurrence of magnetite and serpentine with the alloy, indicate that the mineral is the product of hydrothermal metamorphism and serpentinization of the peridotite. This is confirmed by the discovery of the nickel-iron in serpentine veins cutting moderately altered harzburgite. Andradite garnet, a common skarn mineral produced by contact metamorphism around igneous intrusions, is often intergrown with the nickel-iron. This may indicate that the unusually coarse grain size of the josephinite is the result of the special conditions accompanying igneous intrusion in the serpentine belt.  相似文献   

On the chemical composition of atmospheric aerosols — Part I: Some stoichiometric aspects of the problem     

Henry M. Papée 《Pure and Applied Geophysics》1959,44(1):191-203

Summary Following a recent hypothesis on the role of activated sodium chloride particles as possible condensation and sublimation nuclei, an analysis of data given byC. Junge on the chemical composition of aerosols, is made. It is established that all reported giant nuclei fall into three distinct categories of composition and that within each of these categories the ratio of the sums of anions to the sums of cations for constituents for which analyses were made, remains remarkably constant throughout the days of sampling, and for both geographic positions at which sampling has been carried out. A dependence of the hydroxide-carbonate content, on that of nitrate is also indicated in the «alkaline» nuclei. The system is treated as a saturated solution, and it is shown by the procedure of continuous variations that singularities occur at particular ratios of the prevalent chemical groups in solution, possibly indicating formation of complex species. This, together with the presence of double salts in the solid phase may be partly the reason for the constancy of ratio of sums in the groups of particles studied byJunge, while the grouping itself may depend on the origin and subsequent transformations of the particles.Parts of this paper were presented at the 174-th National Meeting of the American Meteorological Society, on the 29-th of January, 1959, in New York.  相似文献   

Exploration Techniques at the Thorn Ag-Au-Cu High-Sulfidation Epithermal Prospect, Northern British Columbia, Canada     

Henry Awmack 《Resource Geology》2002,52(4):283-290

Abstract. The Thorn prospect is an El Indio-style high-sulfidation epithermal prospect in a little-explored belt of Late Cretaceous subaerial volcanics and subvolcanic intrusions in northwestern British Columbia, Canada. More than 30 massive sulfide (pyrite-enargite-tennantite/tetrahedrite) veins, quartz-sulfide (quartz-pyrite-enargite-tennantite/tetrahedrite) veins and quartz-vuggy silica-alunite veins/breccias fill ENE fractures and faults over an area of 1,600 times 1,900 m. They are hosted within a Late Cretaceous feldspar-quartz-biotite granodioritic porphyry stock and flanked by alteration envelopes a few meters to tens of meters wide: an inner envelope of intense sericite-clay-pyrite and an outer one of weak clay-sericite-chlorite. Where several veins are close together, the sericite-clay-pyrite alteration envelopes coalesce into zones up to 150 m wide.
The most successful exploration techniques have been prospecting, silt and soil geochemistry, airborne magnetic and electromagnetic surveys and diamond drilling. Silt and soil geochemical anomalies for Au, Ag, As, Cu, Pb, Sb and Zn mark the known veins and indicate prospective areas where veins have not yet been discovered. Magnetics and resistivity outline the gross property-wide structure and lithologies. Most of the sericite-clay-pyrite alteration and known veins are outlined by the <264 ohm-m resistivity contour, which covers an area of 800 times 2,300 m. Weak EM conductors are thought to represent undiscovered massive sulfide and quartz-sulfide veins, and their flanking sericite-clay-pyrite alteration.  相似文献   

England on the Eve of the Black Death: An Atlas of Lay Lordship, Land and Wealth, 1300–49 - By BRUCE M.S. CAMPBELL AND KEN BARTLEY     

Henry Sirotin 《Transactions in GIS》2008,12(1):163-164

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Report of an excursion to Farnham: July 17th, 1915     

Henry Bury 《Proceedings of the Geologists' Association. Geologists' Association》1915,26(5):340-342

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Evaluation of a numerical model of the British–Irish ice sheet using relative sea‐level data: implications for the interpretation of trimline observations     

Joseph Kuchar  Glenn Milne  Alun Hubbard  Henry Patton  Sarah Bradley  Ian Shennan  Robin Edwards 《第四纪科学杂志》2012,27(6):597-605

The glacial isostatic adjustment (GIA) of the British Isles is complex due to the interplay between local and non‐local signals. A number of recent studies have modelled the GIA response of the British Isles using relative sea‐level data. This study extends these previous analyses by using output from a numerical glaciological model as input to a GIA model. This is a necessary step towards more realistic GIA models, and although there have been similar studies for the major late Pleistocene ice sheets, this is the first study to do so for the British Isles. We test three reconstructions, classed as ‘minimal’, ‘median’ and ‘maximal’ in terms of their volume at maximum extent, and find it is possible to obtain good data–model fits. The minimal reconstruction is clearly preferred by the sea‐level data. The ice reconstructions tested were not constrained by geomorphological information of past ice extent (lateral and vertical). As a consequence, the reconstructions extend further than much of this information suggests, particularly in terms of ice thickness. It is notable, however, that the reconstructions produce good fits to many sea‐level data from central, mountainous regions (e.g. Scottish highlands), which lends support to the suggestion that trimlines, often used as an constraint on the palaeo ice surface location, are in fact features formed at the transition from warm‐ to cold‐based ice and so mark a minimum constraint on the ice surface altitude. Based on data–model misfits, suggestions are made for improving the ice model reconstructions. However, in many locations, the cause of the misfit could be due to non‐local, predominantly Fennoscandian ice and so interpretation is not straightforward. As a result, we suggest that future analyses of this type consider models and observations for both Fennoscandia and the British Isles. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

The Dakhleh Glass: Product of an impact airburst or cratering event in the Western Desert of Egypt?     

Gordon R. OSINSKI  Johanna KIENIEWICZ  Jennifer R. SMITH  Mark B. E. BOSLOUGH  Mark ECCLESTON  Henry P. SCHWARCZ  Maxine R. KLEINDIENST  Albert F. C. HALDEMANN  Charles S. CHURCHER 《Meteoritics & planetary science》2008,43(12):2089-2107

Abstract— Impact cratering is a ubiquitous geological process on the terrestrial planets. Meteorite impact craters are the most visible product of impact events, but there is a growing recognition that large aerial bursts or airbursts should occur relatively frequently throughout geological time. In this contribution, we report on an unusual impact glass‐the Dakhleh Glass (DG)–which is distributed over an area of ?400 km ²of the Dakhleh Oasis, Egypt. This region preserves a rich history of habitation stretching back to over 400,000 years before the emergence of Homo sapiens. We report on observations made during recent fieldwork and subsequent analytical analyses that strengthen previous suggestions that the DG formed during an impact event. The wide distribution and large size of DG specimens (up to ?50 cm across), the chemistry (e.g., CaO and Al₂O₃ contents up to ?25 and ?18 wt, respectively), the presence of lechatelierite and burnt sediments, and the inclusion of clasts and spherules in the DG is inconsistent with known terrestrial processes of glass formation. The age and other textural characteristics rule out a human origin. Instead, we draw upon recent numerical modeling of airbursts to suggest that the properties of DG, coupled with the absence of a confirmed crater, can best be explained by melting of surficial sediments as a result of a large airburst event. We suggest that glass produced by such events should, therefore, be more common in the rock record than impact craters, assuming that the glass formed in a suitable preserving environment.  相似文献   

A correlation between pulse diagnosis of human body and health monitoring of structures     

C.C.Chang HenryT.Y.Yang 《地震工程与工程振动(英文版)》2004,3(1):117-125

The concept of health monitoring is a key aspect of the field of medicine that has been practiced for a long time. A commonly used diagnostic and health monitoring practice is pulse diagnosis, which can be traced back approximately five thousand years in the recorded history of China. With advances in the development of modem technology, the concept of health monitoring of a variety of engineering structures in several applications has begun to attract widespread attention. Of particular interest in this study is the health monitoring of civil structures. It seems natural, and even beneficial, that these two health-monitoring methods, one as applies to the human body and the other to civil structures, should be analyzed and compared. In this paper, the basic concepts and theories of the two monitoring methods are first discussed. Similarities are then summarized and commented upon. It is hoped that this correlation analysis may help provide structural engineers with some insights into the intrinsic concept of using pulse diagnosis in human health monitoring, which may be of some benefit in the development of modem structural health monitoring methods.  相似文献   

Anisotropic elastic full‐waveform inversion of walkaway vertical seismic profiling data from the Arabian Gulf          下载免费PDF全文

John C Owusu  Marwan Charara  Scott Leaney  Allan Campbell  Shujaat Ali  Igor Borodin  Les Nutt  Henry Menkiti 《Geophysical Prospecting》2016,64(1):38-53

Borehole seismic addresses the need for high‐resolution images and elastic parameters of the subsurface. Full‐waveform inversion of vertical seismic profile data is a promising technology with the potential to recover quantitative information about elastic properties of the medium. Full‐waveform inversion has the capability to process the entire wavefield and to address the wave propagation effects contained in the borehole data—multi‐component measurements; anisotropic effects; compressional and shear waves; and transmitted, converted, and reflected waves and multiples. Full‐waveform inversion, therefore, has the potential to provide a more accurate result compared with conventional processing methods. We present a feasibility study with results of the application of high‐frequency (up to 60 Hz) anisotropic elastic full‐waveform inversion to a walkaway vertical seismic profile data from the Arabian Gulf. Full‐waveform inversion has reproduced the majority of the wave events and recovered a geologically plausible layered model with physically meaningful values of the medium.  相似文献   

Forecasting search areas using ensemble ocean circulation modeling   总被引：1，自引：1，他引：0  

Arne Melsom  Fran?ois Counillon  Joseph Henry LaCasce  Laurent Bertino 《Ocean Dynamics》2012,62(8):1245-1257

We investigate trajectory forecasting as an application of ocean circulation ensemble modeling. The ensemble simulations are performed weekly, starting with assimilation of data for various variables from multiple sensors on a range of observational platforms. The ensemble is constructed from 100 members, and member no. 1 is designed as a standard (deterministic) simulation, providing us with a benchmark for the study. We demonstrate the value of the ensemble approach by validating simulated trajectories using data from ocean surface drifting buoys. We find that the ensemble average trajectories are generally closer to the observed trajectories than the corresponding results from a deterministic forecast. We also investigate an alternative model in which velocity perturbations are added to the deterministic results and ensemble mean results, by a first-order stochastic process. The parameters of the stochastic model are tuned to match the dispersion of the ensemble approach. Search areas from the stochastic model give a higher hit ratio of the observations than the results based on the ensemble. However, we find that this is a consequence of a positive skew of the area distribution of the convex hulls of the ensemble trajectory end points.  相似文献