Crustal structure beneath exposed accreted terranes of Southern Alaska     

G.S. Fuis  E.L. Ambos  W.D. Mooney  R.A. Page  M.A. Fisher  T.M. Brocher  J.J. Taber 《Geophysical Journal International》1987,89(1):73-78

Summary. The crustal structure beneath the exposed terranes of southern Alaska has been explored using coincident seismic refraction and reflection profiling. A wide-angle reflector at 8–9 km depth, at the base of an inferred low-velocity zone, underlies the Peninsular and Chugach terranes, appears to truncate their boundary, and may represent a horizontal decollement beneath the terranes. The crust beneath the Chugach terrane is characterized by a series of north-dipping paired layers having low and high velocities that may represent subducted slices of oceanic crust and mantle. This layered series may continue northward under the Peninsular terrane. Earthquake locations in the Wrangell Benioff zone indicate that at least the upper two low-high velocity layer pairs are tectonically inactive and that they appear to have been accreted to the base of the continental crust. The refraction data suggest that the Contact fault between two similar terranes, the Chugach and Prince William terranes, is a deeply penetrating feature that separates lower crust (deeper than 10 km) with paired dipping reflectors, from crust without such reflectors.  相似文献   

The XMM-SSC survey of hard-spectrum XMM–Newton sources – I. Optically bright sources     

M. J. Page  I. Lehmann  Th. Boller  M. G. Watson  T. Dwelly  S. Hess  I. Matute  N. S. Loaring  S. Rosen  H. Ziaeepour  A. Schwope  G. Lamer  F. J. Carrera  J. Tedds  R. Della Ceca  P. Severgnini  R. G. McMahon  W. Yuan 《Monthly notices of the Royal Astronomical Society》2007,378(4):1335-1355

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Confirming the high velocity outflow in PG1211+143     

K. A. Pounds  K. L. Page 《Monthly notices of the Royal Astronomical Society》2006,372(3):1275-1278

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Swift observations of the X-ray and UV evolution of V2491 Cyg (Nova Cyg 2008 No. 2)     

K. L. Page  J. P. Osborne  P. A. Evans  G. A. Wynn  A. P. Beardmore  R. L. C. Starling  M. F. Bode  A. Ibarra  E. Kuulkers  J.-U. Ness  G.J. Schwarz 《Monthly notices of the Royal Astronomical Society》2010,401(1):121-130

We present extensive, high-density Swift observations of V2491 Cyg (Nova Cyg 2008 No. 2). Observing the X-ray emission from only one day after the nova discovery, the source is followed through the initial brightening, the super-soft source phase and back to the pre-outburst flux level. The evolution of the spectrum throughout the outburst is demonstrated. The UV and X-ray light curves follow very different paths, although changes occur in them around the same times, indicating a link between the bands. Flickering in the late-time X-ray data indicates the resumption of accretion. We show that if the white dwarf (WD) is magnetic, it would be among the most magnetic known; the lack of a periodic signal in our later data argues against a magnetic WD, however. We also discuss the possibility that V2491 Cyg is a recurrent nova, providing recurrence time-scale estimates.  相似文献   

Assessment of polycyclic aromatic hydrocarbon exposure in the waters of Prince William Sound after the Exxon Valdez oil spill: 1989-2005     

Boehm PD  Neff JM  Page DS 《Marine pollution bulletin》2007,54(3):339-356

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The distribution of absorption in AGN detected in the XMM–Newton observations of the CDFS     

T. Dwelly  M. J. Page 《Monthly notices of the Royal Astronomical Society》2006,372(4):1755-1775

We have used very deep XMM–Newton observations of the Chandra Deep Field -South to examine the spectral properties of the faint active galactic nucleus (AGN) population. Crucially, redshift measurements are available for 84 per cent (259/309) of the XMM–Newton sample. We have calculated the absorption and intrinsic luminosities of the sample using an extensive Monte Carlo technique incorporating the specifics of the XMM–Newton observations. 23 sources are found to have substantial absorption and intrinsic X-ray luminosities greater than 10⁴⁴ erg s⁻¹, putting them in the 'type-2' QSO regime. We compare the redshift, luminosity and absorption distributions of our sample to the predictions of a range of AGN population models. In contrast to recent findings from ultradeep Chandra surveys, we find that there is little evidence that the absorption distribution is dependent on either redshift or intrinsic X-ray luminosity. The pattern of absorption in our sample is best reproduced by models in which ∼75 per cent of the AGN population is heavily absorbed at all luminosities and redshifts.  相似文献   

Preserving the unpreservable: a lost world rediscovered at Christian Malford, UK     

Philip R. Wilby  Keith Duff  Kevin Page  & Susan Martin 《Geology Today》2008,24(3):95-98

The small village of Christian Malford, Wiltshire (UK) is known to palaeontologists the world over because of the chance discovery of an astonishing fossil bonanza in the mid-nineteenth century. Pits in the Jurassic Oxford Clay yielded thousands of specimens of exquisitely preserved ammonites, fish and crustaceans, but became most famous for squid-like cephalopods and belemnites (collectively termed coleoids) with fossilized soft-parts. The precise location of the find has remained obscure, until now, and a new attempt is underway to understand the ancient environment that triggered this unusual preservation.  相似文献   

Characterization of the Sukinda and Nausahi ultramafic complexes,Orissa, India by platinum-group element geochemistry     

Norman J Page  P.K Banerji  Joseph Haffty 《Precambrian Research》1985,30(1):27-41

Samples of 20 chromitite, 14 ultramafic and mafic rock, and 9 laterite and soil samples from the Precambrian Sukinda and Nausahi ultramafic complexes, Orissa, India were analyzed for platinum-group elements (PGE). The maximum concentrations are: palladium, 13 parts per billion (ppb); platinum, 120 ppb; rhodium, 21 ppb; iridium, 210 ppb; and ruthenium, 630 ppb. Comparison of chondrite-normalized ratios of PGE for the chromitite samples of lower Proterozoic to Archean age with similar data from Paleozoic and Mesozoic ophiolite complexes strongly implies that these complexes represent Precambrian analogs of ophiolite complexes. This finding is consistent with the geology and petrology of the Indian complexes and suggests that plate-tectonic and ocean basin developement models probably apply to some parts of Precambrian shield areas.  相似文献   

Implications of simultaneously mitigating and adapting to climate change: initial experiments using GCAM     

Katherine Calvin  Marshall Wise  Leon Clarke  Jae Edmonds  Page Kyle  Patrick Luckow  Allison Thomson 《Climatic change》2013,117(3):545-560

Most research on future climate change discusses mitigation and impacts/adaptation separately. However, mitigation will have implications for impacts and adaptation. Similarly, impacts and adaptation will affect mitigation. This paper begins to explore these two veins of research simultaneously using an integrated assessment model. We begin by discussing the types of interactions one might expect by impact sector. Then, we develop a numerical experiment in the agriculture sector to illustrate the importance of considering mitigation, impacts, and adaptation at the same time. In our experiment, we find that climate change can reduce crop yields, resulting in an expansion of cropland to feed a growing population and a reduction in bioenergy production. These two effects, in combination, result in an increase in the cost of mitigation.  相似文献   

The X-ray spectrum of NGC 7213 and the Seyfert–LINER connection     

R. L. C. Starling  M. J. Page  G. Branduardi-Raymont  A. A. Breeveld  R. Soria  K. Wu 《Monthly notices of the Royal Astronomical Society》2005,356(2):727-733

We present an XMM–Newton observation of the Seyfert–LINER (low-ionization nuclear emission-line region) galaxy NGC 7213. The RGS soft X-ray spectrum is well fitted with a power law plus soft X-ray collisionally ionized thermal plasma  ( kT = 0.18^+0.03_−0.01 keV)  . We confirm the presence of Fe  i , Fe  xxv and Fe  xxvi Kα emission in the EPIC spectrum and set tighter constraints on their equivalent widths of  82⁺¹⁰₋₁₃, 24⁺⁹₋₁₁  and 24⁺¹⁰₋₁₃ eV, respectively. We compare the observed properties together with the inferred mass accretion rate of NGC 7213 with those of other Seyfert and LINER galaxies. We find that NGC 7213 has intermediate X-ray spectral properties lying between those of the weak active galactic nucleus found in the LINER M81 and higher-luminosity Seyfert galaxies. There appears to be a continuous sequence of X-ray properties from the Galactic Centre through LINER galaxies to Seyferts, probably determined by the amount of material available for accretion in the central regions.  相似文献