Lower and Middle Ordovician conodonts of Laurentian affinity from blocks of limestone in the Rosroe Formation,South Mayo Trough,western Ireland and their palaeogeographic implication     

Svend Stouge  David A. T. Harper  George D. Sevastopulo  Darren O'Mahony  John Murray 《Geological Journal》2016,51(4):584-599

The Middle Ordovician Rosroe Formation consists of some 1350 m of coarse, mainly siliciclastic to volcaniclastic sedimentary rocks, deposited in a submarine fan environment, and is restricted to the southern limb of the South Mayo Trough, western Ireland. Discrete allochthonous blocks, reaching 5 m in size, are present in the formation at several localities. Conodonts recovered from these blocks, collected from two separate locations, are of late Early and mid Mid Ordovician age. The conodonts have high conodont‐alteration indices (CAI 5) indicative of temperatures as high as 300^o to max. 480 °C; some found in the Lough Nafooey area have abnormally high indices (CAI 6), which correspond to temperatures of about 360^o to max. 550 °C. The oldest fauna is dominated by Periodon aff. aculeatus and characterized by Oepikodus evae typical of the Oepikodus evae Zone (Floian Stage; Stage Slices Fl2–3, Lower Ordovician). The younger conodont assemblage, characterized by Periodon macrodentatus associated with Oistodella pulchra, is referred to the P. macrodentatus conodont Biozone (lower Darriwilian; Stage Slices Dw1–2). The Rosroe conodont assemblages are of Laurentian affinity; comparable faunas are well known from several locations along the east to south‐eastern platform margin of Laurentia and the Notre Dame subzone of central Newfoundland, Canada. The faunal composition from the limestone blocks suggests a shelf edge to slope (or fringing carbonate) setting. The faunal assemblages are coeval with, respectively, the Tourmakeady Formation (Floian–Dapingian) and Srah Formation (Darriwilian) in the Tourmakeady Volcanic Group in the eastern part of the South Mayo Trough and probably are derived from the same or similar laterally equivalent short‐lived carbonate successions that accumulated at offshore ‘peri‐Laurentian’ islands, close to and along the Laurentian margin. During collapse of the carbonate system in the late Mid Ordovician, the blocks were transported down a steep slope and into deep‐water by debris flows, mixing with other rock types now found in the coarse polymict clastics of the Rosroe Formation. The faunas fill the stratigraphical ‘gap’ between the Lower Ordovician Lough Nafooey Volcanic Group and the upper Middle Ordovician Rosroe Formation in the South Mayo Trough and represent a brief interval conducive to carbonate accumulation in an otherwise siliciclastic‐ and volcaniclastic‐dominated sedimentary environment. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Disc precession in the M31 dipping X-ray binary Bo 158?     

R. Barnard  S. B. Foulkes  C. A. Haswell  U. Kolb  J. P. Osborne  J. R. Murray 《Monthly notices of the Royal Astronomical Society》2006,366(1):287-294

We present results from three XMM–Newton observations of the M31 low mass X-ray binary (LMXB) XMMU J004314.4+410726.3 (Bo 158), spaced over 3 d in 2004 July. Bo 158 was the first dipping LMXB to be discovered in M31. Periodic intensity dips were previously seen to occur on a 2.78-h period, due to absorption in material that is raised out of the plane of the accretion disc. The report of these observations stated that the dip depth was anticorrelated with source intensity. In light of the 2004 XMM–Newton observations of Bo 158, we suggest that the dip variation is due to precession of the accretion disc. This is to be expected in LMXBs with a mass ratio ≲0.3 (period ≲4 h), as the disc reaches the 3:1 resonance with the binary companion, causing elongation and precession of the disc. A smoothed particle hydrodynamics simulation of the disc in this system shows retrograde rotation of a disc warp on a period of  ∼11 P _orb  , and prograde disc precession on a period of  29 ± 1 P _orb  . This is consistent with the observed variation in the depth of the dips. We find that the dipping behaviour is most likely to be modified by the disc precession, hence we predict that the dipping behaviour repeats on an  81 ± 3 h  cycle.  相似文献   

Helical magnetic fields associated with the relativistic jets of four BL Lac objects     

Denise C. Gabuzda  Éamonn Murray  Patrick Cronin 《Monthly notices of the Royal Astronomical Society》2004,351(4):L89-L93

  相似文献   

A Chandra observation of the interacting pair of galaxies NGC 4485/4490     

T. P. Roberts  R. S. Warwick  M. J. Ward  S. S. Murray 《Monthly notices of the Royal Astronomical Society》2002,337(2):677-692

  相似文献   

The NASA Astrophysics Data System: Free Access to the Astronomical Literature On-line and through Email     

Guenther Eichhorn  Alberto Accomazzi  Carolyn S. Grant  Michael J. Kurtz  Stephen S. Murray 《Astrophysics and Space Science》2002,282(1):299-340

The Astrophysics Data System (ADS) provides access to the astronomical literature through the World Wide Web. It is a NASA funded project and access to all the ADS services is free to everybody world-wide. The ADS Abstract Service allows the searching of four databases with abstracts in Astronomy, Instrumentation, Physics/Geophysics, and the LANL Preprints with a total of over 2.2 million references. The system also provides access to reference and citation information, links to on-line data, electronic journal articles, and other on-line information. The ADS Article Service contains the full articles for most of the astronomical literature back to volume 1. It contains the scanned pages of all the major journals (Astrophysical Journal, Astronomical Journal, Astronomy & Astrophysics, Monthly Notices of the Royal Astronomical Society, and Solar Physics), as well as most smaller journals back to volume 1.The ADS can be accessed through any web browser without signup or login. Alternatively an email interface is available that allows our users to execute queries via email and to retrieve scanned articles via email. This might be interesting for users on slow or unreliable links, since the email system will retry sending information automatically until the transfer is complete. There are now 9 mirror sites of the ADS available in different parts of the world to improve access. The ADS is available at: http://ads.harvard.edu This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Forgotten coast,forgotten people: sustainable development and disproportionate impacts from Hurricane Michael in Gulf County,Florida     

Boda  Chad S.  Scown  Murray W.  Faran  Turaj 《Natural Hazards》2022,111(1):877-899

Natural Hazards - A central challenge for sustainable development is how societies are to avoid, minimize or address impacts from anthropogenic climate change. However, competing perspectives on...  相似文献   

Glaciers and environmental change. A. Nesje and S.V. Dahl. Publisher Arnold,London 2000 (203 pp) £45.00 (hardback) ISBN 0‐340‐70637‐6 £18.99 (paperback) ISBN 0‐340‐70634‐1     

Murray Gray 《第四纪科学杂志》2001,16(2):200-200

  相似文献   

Optical and X-ray observations of the neutron star soft X-ray transient XTE J1709–267     

P. G. Jonker †  D. K. Galloway  J. E. McClintock  M. Buxton  M. Garcia  S. Murray 《Monthly notices of the Royal Astronomical Society》2004,354(3):666-674

  相似文献   

The origin of the rebrightening in soft X-ray transient outbursts     

M. R. Truss  G. A. Wynn  J. R. Murray  A. R. King 《Monthly notices of the Royal Astronomical Society》2002,337(4):1329-1339

  相似文献   

Propagation of solar flare-associated interplanetary shock waves in the heliospheric meridional plane   总被引：4，自引：0，他引：4  

Wei Fengsi  Murray Dryer 《Solar physics》1991,132(2):373-394

We have analyzed 149 flare-associated shock wave events based on interplanetary scintillation (IPS) observational data. All of the flare-associated shock waves tend to propagate toward the low latitude region near the solar equator for flares that are located in both the solar northern and southern hemispheres. Also, the fastest propagation directions tend toward the heliospheric current sheet near 1 AU. We suggest that this tendency is caused by the dynamic action of near-Sun magnetic forces on the ejected coronal plasma that traverses the helmet-like magnetic topologies near the Sun outward to the classical topology that is essentially parallel to the heliospheric current sheet.  相似文献