U-Th-Pb isotope systematics related to igneous rocks and ore Pb,Mount Isa,Queensland     

Farquharson  R. B.  Richards  J. R. 《Mineralium Deposita》1974,9(4):339-356

This study is a search for a genetic relationship between Pb sulphide ore and igneous rocks in the region of Mount Isa, Queensland. The approach involves derivation of Pb isotope initial ratios by the whole-rock isochron method, and comparison of the initial ratios (Pb²⁰⁶/Pb²⁰⁴, Pb²⁰⁷/Pb²⁰⁴ and Pb²⁰⁸/Pb²⁰⁴) with the isotopic composition of the ore Pb. Data are reported for four igneous units; Kalkadoon granodiorite, Kalkadoon adamellite, Sybella granite and Eastern Creek volcanics. The results display considerable scatter for each of the units, and reveal the effects of recent surficial loss of U. The positioning of isochrons is aided by previous Rb-Sr geochronological data wherever possible. Comparison of initial ratios and ore Pb suggests that none of the igneous rock units is co-genetic with the ore deposit. Both phases of the Sybella Granite are more radiogenic and are apparently younger than the ore Pb. The Kalkadoon Granite is possibly related to the ore through some post-emplacement process of extraction and transport of Pb (e.g. by erosion or by anatectic magma generation) to the present site of the orebodies.  相似文献   

Photometric study of new southern SU UMa-type dwarf novae and candidates – III. NSV 10934, MM Sco, AB Nor and CAL 86     

Taichi Kato  Peter Nelson  Chris Stockdale  Berto Monard  Tom Richards  Rod Stubbings  Hitoshi Yamaoka  Bernard Heathcote  Roland Santallo 《Monthly notices of the Royal Astronomical Society》2004,347(3):861-872

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Numerical analysis of meteotsunamis in the Northeastern Gulf of Mexico     

Cheng  Wei  Horrillo  Juan  Sunny  Richards 《Natural Hazards》2022,110(3):1719-1734

Natural Hazards - Although relatively rare, meteotsunamis are capable of causing coastal infrastructure damage and casualties. Analyses of water level and meteorological data in the U.S. show that...  相似文献   

MERLIN polarimetry of the OH masers in IRAS 20406+2953     

I. Bains  A. M. S. Richards  T. M. Gledhill  J. A. Yates 《Monthly notices of the Royal Astronomical Society》2004,354(2):529-542

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A radio jet in the prototypical symbiotic star Z And?     

C. Brocksopp  J. L. Sokoloski  C. Kaiser  A. M. Richards  T. W. B. Muxlow  N. Seymour 《Monthly notices of the Royal Astronomical Society》2004,347(2):430-436

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Simulating H2O Maser Emission in the Mass Outflows from Evolved Stars     

J. A. Yates  E. M. L. Humphreys  A. M. S. Richards 《Astrophysics and Space Science》1997,251(1-2):285-288

The combination of a time-dependent spherically symmetric hydrodynamic model of stellar atmosphere pulsation and a radiation transport code, which incorporates maser saturation theory, enabled us to synthesise maps and spectra of H₂O maser emission from the circumstellar envelopes of long period variable stars. The synthetic maps and spectra compare favourably with observed 22, 321 and 325 GHz H₂O maser emission. As is observed in H₂O maser regions the peak emission occurs between 3–8 stellar radii from the star. The calculated H₂O maser regions are in conditions of n_H2 = 10⁶ − 10⁸ cm⁻³, assuming a fractional abundance of 10⁻⁴; kinetic temperatures of 550–3000 K; dust ensemble temperatures of 500–1200 K and an accelerating velocity field. The IR radiation field is explicitly included in the radiation transport model, incorporating the latest absorption efficiency data for silicates from Draine. We reproduce the features seen in high angular resolution MERLIN spectral line datacubes. This shows that a mass outflow model which extends the photosphere using pulsations and incorporates radiation pressure on silicate based dust particles can produce the observed data on small (10-mas) angular scales. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献   

A multi‐technique study of the glacial stratigraphy of Co. Clare and Co. Kerry,southwest Ireland     

Andrew E. Richards 《第四纪科学杂志》2002,17(3):261-276

A multi‐technique approach has been adopted in a study of the lithostratigraphy of glacial deposits in southwestern Ireland, including clast lithological analysis, fine sand geochemistry, low frequency mass specific susceptibility and fine sand calcium carbonate (equivalent) content. A revised lithostratigraphical scheme is suggested for the Quaternary glacial deposits of the region, together with a simple strategy that may be adopted for stratigraphical studies in other regions of southern Ireland. It appears that geochemical determinations via inductively coupled plasma–atomic absorption spectrometry are particularly useful in characterising and discriminating between till units within local stratigraphical studies and may be used to inform the applicability of other utilitarian techniques for use on a regional scale. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Deflection of plumes by mantle shear flow: experimental results and a simple theory   总被引：4，自引：0，他引：4  

Mark A. Richards  Ross W. Griffiths 《Geophysical Journal International》1988,94(3):367-376

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APEX-SZ a Sunyaev–Zel’dovich galaxy cluster survey     

D. Schwan  F. Bertoldi  S. Cho  M. Dobbs  R. Guesten  N. W. Halverson  W. L. Holzapfel  E. Kreysa  T. M. Lanting  A. T. Lee  M. Lueker  J. Mehl  K. Menten  D. Muders  M. Myers  T. Plagge  A. Raccanelli  P. Schilke  P. L. Richards  H. Spieler  M. White 《New Astronomy Reviews》2003,47(11-12):933

The APEX-SZ experiment is a sky survey designed to discover galaxy clusters via the Sunyaev–Zel’dovich effect at millimeter wavelengths. We describe the components of the instrument, including the 12 m Atacama Pathfinder Experiment telescope, optics, Transition-edge sensor bolometer array and SQUID readout. APEX-SZ will begin observations in 2004.  相似文献   

Suspended sediment dynamics in a steep,glacier‐fed mountain stream,Place Creek,Canada     

G. Richards  R. D. Moore 《水文研究》2003,17(9):1733-1753

This study examined suspended sediment concentration (SSC) during the ablation seasons of 2000 and 2001 in Place Creek, Canada, a steep, glacier‐fed mountain stream. Comparison of stream flow in Place Creek with that in an adjacent, almost unglacierized catchment provided a rational basis for separating the ablation seasons into nival, nival–glacial, glacial and autumn recession subseasons. Distinct groupings of points in plots of electrical conductivity against discharge supported the validity of the subseasonal divisions in terms of varying hydrological conditions. Relationships between SSC and discharge (Q) varied between the two study seasons, and between subseasons. Hysteresis in the SSC–Q relationship was evident at both event and weekly time‐scales. Some suspended sediment released from pro‐glacial Place Lake (the source of Place Creek) appeared to be lost to channel storage at low flows, especially early in the ablation season, with re‐entrainment at higher flows. Multiple regression models were derived for the subseasons using predictor variables including Q, Q², the change in Q over the previous 3 h, cumulative discharge over the ablation season, total precipitation over the previous 24 h and SSC measured at 1500 hours as an index value for each day. The models produced adjusted R² values ranging from 0·71 to 0·91, and provided tentative insights into the differences in SSC dynamics amongst subseasons. Introduction of the index value of SSC significantly improved the model fit during the nival–glacial and glacial subseasons for both years, as it adjusts the model to the current condition of sediment supply. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献