Announcements     

H. J. B. Birks  Hilary H. Birks 《Journal of Paleolimnology》1988,1(1):84-84

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MicroRaman spectroscopy of diamond and graphite in Almahata Sitta and comparison with other ureilites     

Aidan J. ROSS  Andrew STEELE  Marc D. FRIES  Lukas KATER  Hilary DOWNES  Adrian P. JONES  Caroline L. SMITH  Peter M. JENNISKENS  Michael E. ZOLENSKY  Muawia H. SHADDAD 《Meteoritics & planetary science》2011,46(3):364-378

This work is the first detailed study of carbon phases in the ureilite Almahata Sitta (sample #7). We present microRaman data for diamond and graphite in Almahata Sitta, seven unbrecciated ureilites, and two brecciated ureilites. Diamond in Almahata Sitta was found to be distinct from that in unbrecciated and brecciated ureilites, although diamond in unbrecciated and brecciated ureilites is indistinguishable. Almahata Sitta diamond shows a peak center range of 1318.5–1330.2 cm^?1 and a full width at half maximum (FWHM) range of 6.6–17.4 cm^?1, representing a shock pressure of at least 60 kbar. The actual peak shock pressure may be higher than this due to postshock annealing, if shock synthesis is the source of ureilite diamonds. Diamond in unbrecciated and brecciated ureilites have peak center wave numbers closer to terrestrial kimberlite diamond, but show a wider range of FWHM than Almahata Sitta. The larger peak shift observed in Almahata Sitta may indicate the presence of lonsdaleite. Alternatively, the lower values in brecciated ureilites may be evidence of an annealing step either following the initial diamond‐generating shock or as a consequence of heating during reconsolidation of the breccia. Graphite in Almahata Sitta shows a G‐band peak center range of 1569.1–1577.1 cm^?1 and a G‐band FWHM range of 24.3–41.6 cm^?1 representing a formation temperature of 990 ± 120 °C. Amorphous carbon was also found. We examine the different theories for diamond formation in ureilites, such as chemical vapor deposition and shock origin from graphite, and explore explanations for the differences between Almahata Sitta and other ureilites.  相似文献   

Late Weichselian environmental change in Norway,including Svalbard     

Hilary H. Birks  Aage Paus  J. I. Svenndse  Torbjrn Alm  J. Mangerud  J. Y. Landvik 《第四纪科学杂志》1994,9(2):133-145

A synthesis of the principal environmental changes that are inferred to have occurred in Norway and Svalbard (Fig. 1) during the Late-glacial period (14-9 ka BP) is presented. The paper has three sections dealing separately with (I) western Norway, (II) northern Norway and (III) Spitsbergen, Svalbard. The main conditions described include glacial events, sea-level changes, vegetation history and climatic variations. A summary chart of environmental reconstructions is presented for each of the three areas, each including a curve of temperature reconstructions for the Late-glacial period. These indicate some significant regional variations in contemporaneous thermal conditions during the Late-glacial.  相似文献   

Characteristics of the lithospheric mantle beneath East Serbia inferred from ultramafic xenoliths in Palaeogene basanites     

Vladica?Cvetkovi?Email author  Hilary?Downes  Dejan?Prelevi?  Milivoje?Jovanovi?  Marina?Lazarov 《Contributions to Mineralogy and Petrology》2004,148(3):335-357

Mantle xenoliths from Paleogene basanites of East Serbia were studied using EMP and LA-ICP-MS techniques in order to better understand mantle characteristics in this region. Five different mantle lithologies have been distinguished: a dunite/harzburgite/lherzolite (D/HZ/L) group, clinopyroxene-rich lherzolites (Cpx-L), clinopyroxene megacrysts (Cpx-M), spinel-rich olivine websterites (OWB₁) and spinel-poor olivine websterites (OWB₂). D/HZ/L xenoliths are the most common and represent normal mantle composed of typical anhydrous spinel peridotites with well equilibrated, unzoned silicates characterized by high Mg# s. Negative correlations between Mg# and TiO₂, Al₂O₃ and CaO wt% in clinopyroxenes (cpx) and orthopyroxenes (opx) and the Cr–Al trend in spinel (sp) suggest depletion via extraction of basaltic melts. The modal composition of D/HZ/L xenoliths and unusual low-Al opx suggest that the lithospheric mantle underneath East Serbia is more depleted than normal European lithosphere. D/HZ/L xenoliths contain numerous pockets and veins filled by Cr-rich cpx, Ti-rich spinel, altered glass, apatite and rare ilmenite and phlogopite. Petrographic observations, supported by major element contents in sp and cpx, and modelling using trace element contents in cpx, indicate that the pockets and veins formed from infiltration of alkaline melts and reaction with peridotite wall-rock causing opx and spinel replacement. The same alkaline melt-related metasomatism gave rise to the Cpx-L and OWB₁ mantle xenoliths and Cpx-M xenocrysts. Trace element contents of cpx in these xenoliths show a distinctively concave downwards REE pattern with a HFSE depletion, very similar to cpx megacrysts from the Pannonian Basin and to vein cpx from Eifel. In contrast, the OWB₂ xenoliths show evidence of precipitation from subduction-related mafic to ultramafic melts, as inferred from their opx-rich lithology and unusual Cr-rich spinels. They are probably related to subduction magmatism during the Late Cretaceous.Milivoje Jovanovi: deceased in April 2004  相似文献   

Geodynamic significance of ultramafic xenoliths from Eastern Serbia: Relics of sub-arc oceanic mantle?     

Vladica Cvetkovi&#x;  Hilary Downes  Dejan Prelevi&#x;  Marina Lazarov  Kristina Resimi&#x;-&#x;ari&#x; 《Journal of Geodynamics》2007,43(4-5):504-527

A suite of highly depleted peridotite xenoliths in East Serbian Palaeogene basanites represents the lithospheric mantle beneath the Balkan Peninsula. The xenoliths are harzburgites, clinopyroxene-poor lherzolites and rare dunites. They contain mostly <5 vol.% of modal clinopyroxene and are characterized by high Mg# in silicates (>91), high Cr# in spinel (mostly 0.5–0.7), and by distinctively low Al₂O₃ contents in orthopyroxene (mostly 1–2 wt.%). They have experienced some mantle metasomatism which has slightly obscured their original composition. Nevertheless, the general characteristics of the xenoliths imply a composition which is significantly more depleted than most non-cratonic sub-continental mantle xenolith suites, as well as orogenic peridotites and abyssal peridotites. Geological and compositional evidence suggests that the xenoliths do not represent Archean mantle. The existence of Proterozoic mantle cannot be entirely excluded, although it is in disagreement with geological evidence. On the other hand, the studied xenoliths are compositionally very similar to peridotites of modern oceanic sub-arc settings. The existence of such a depleted lithospheric mantle segment is also inferred from the presence of rare orthopyroxene-rich xenoliths in the same suite. These are interpreted to have originated as lithospheric precipitates of high-Mg, SiO₂-saturated magmas that require a highly depleted mantle source. Such source is typically required by boninitic-like magmas of intraoceanic suprasubduction settings. A proposed geodynamic model to explain these observations involves accretion or underplating of the lower parts of the Tethyan oceanic lithosphere during the Upper Jurassic closure of the eastern branch of the Vardar ocean.  相似文献   

The Kråkenes late-glacial palaeoenvironmental project   总被引：1，自引：0，他引：1  

Hilary H. Birks  R. W. Battarbee  D. J. Beerling  H. J. B. Birks  S. J. Brooks  C. A. Duigan  S. Gulliksen  H. Haflidason  F. Hauge  V. J. Jones  B. Jonsgard  M. Kårevik  E. Larsen  G. Lemdahl  R. Løvlie  J. Mangerud  S. M. Peglar  G. Possnert  J. P. Smol  J. O. Solem  I. Solhøy  T. Solhøy  E. Sønstegaard  H. E. Wright 《Journal of Paleolimnology》1996,15(3):281-286

Kråkenes is the site of a small lake on the west coast of Norway that contains a long sequence of late-glacial sediments. The Younger Dryas is well represented, as a cirque glacier developed in the catchment at this time. This site offers unique opportunities to reconstruct late-glacial environments from independent sources of evidence; physical evidence (glacial geomorphology, sedimentology, palaeomagnetism, radiocarbon dating), and biological evidence from the remains of animals and plants derived from both the terrestrial and aquatic ecosystems. This report describes the background to the site, and the international multidisciplinary project to reconstruct late-glacial and early Holocene environmental and climatic changes at Kråkenes.  相似文献   

My life with macrofossils     

Hilary H. Birks 《Journal of Paleolimnology》2017,57(2):181-200

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Book reviews     

Richard Le Heron  David Mercer  Richard T. Jackson  Hilary P. M. Winchester  Peter L. Simons  M. A. J. WilliamS 《The Australian geographer》1990,21(2):174-196

A WORLD IN CRISIS? Geographical Perspectives (second edition) edited by R. J. Johnston and P. J. Taylor. 15 x 23 cm, x and 371 pages. Basil Blackwell: Oxford 1989 (ISBN 0 631 16271 2) $A34.95 (soft).

INTEGRATED RURAL DEVELOPMENT PROGRAMMES IN PAPUA NEW GUINEA: External Aid and Provincial Planning (IASER Monograph No 28) by R. Crittenden and D. A. M. Lea, 17 x 24 cm, xv and 132 pages. Papua New Guinea Institute of Applied Social and Economic Research and Department of Geography and Planning, University of New England: Armidale 1989 (ISBN 9980 75 018 9).

ACCOMMODATING INEQUALITY: Gender and Housing by Sophie Watson. 14 x 21 cm, x and 157 pages. Allen & Unwin: Sydney 1988 (ISBN 0 04 320209 2) $A 14.95 (soft).

A SHORT HISTORY OF GEOMORPHOLOGY by K. J. Tinkler. 14 x 22 cm, xviii and 317 pages, Croom Helm: London 1985 (ISBN 0 7099 2441 0) $A49.95 (hard).

PATHWAYS IN GEOLOGY: Essays in Honour of

Edwin Sherbon Hills edited by R. W. Le Mai‐

tre. 25 x 19 cm, viii and 463 pages. Basil

Blackwell: Melbourne 1989 (ISBN

0731682416) $A110.00 (hard).

CHANGING THE FACE OF THE EARTH: Culture, Environment, History by I. G. Simmons. 17 x 24 cm, xiii and 487 pages. Basil Blackwell: Oxford 1989 (ISBN 0 631 16351 4) $A49.95 (soft).

PLANNED TO DEATH: The Annihilation of a Place Called Howdendyke by J. D. Porteous. 16 x 24 cm, xiii and 254 pages. Manchester University Press: Manchester 1989 (ISBN 0 7190 2831 0) £35.00 (hard).

A SOCIAL ATLAS OF DARWIN: 1986. Census of Population and Housing by J. Taylor and D.

Jaensch. 21 x 29 cm, and 66 pages. Australian Bureau of Statistics and North Australia Research Unit: Darwin 1989 (ISBN 0 642 143322 6).

ATLAS OF DEMOGRAPHIC CHANGE IN THE SOUTH EAST REGION OF NEW SOUTH WALES 1861–1991 by Terry G. Birtles and Jane E. Gordon. 21 x 29 cm, v and 141 pages. Canberra College of Advanced Education: Belconnen 1989 (ISBN 0 85889 355 5 $A40.00 (soft).

LABOUR ADJUSTMENT IN METROPOLITAN REGIONS by P. S. Morrison 15 x 21 cm, ix and 254 pages. Victoria University Press: Wellington 1989 (ISBN 0 86473 190 6) SA25.00 (soft).

AUSTRALIAN REGIONAL DEVELOPMENTS: Readings in Regional Experiences, Policies and Prospects (Australian Regional Developments No. 10) edited by B. Higgins and K. Zagorski. 17 x 25 cm. xi and 260 pages. AGPS Press: Canberra 1989 (ISBN 0 644 0935).

SOUTH AUSTRALIAN MANUFACTURING IN TRANSITION edited by T. J. Mules. 15 x 21 cm, vii and 188 pages. Wakefield Press (for Centre of South Australian Economic Studies): Adelaide 1989 (ISBN 909591 74 1) $A24.95 (soft).

COUNTERURBANIZATION: The Changing Pace’ and Nature of Population Deconcentration edited by A. G. Champion. 16 x 24 cm, xxii and 266 pages. Edward Arnold: London 1989 (ISBN 0 7131 6614 2) £27.00 (hard).

THE HUMANE CITY: Cities as if People Matter by J. R. Short. 15 x 22 cm, 167 pages. Basil Blackwell: Oxford 1989 (ISBN 0 631 15824 3) $A27.95 (soft).

THE TORRES STRAIT: People and History (revised edition) by J. Singe. 13 x 19 cm, xviii and 261 pages. University of Queensland Press: St Lucia 1989 (first published in 1979) (ISBN 0 7022 2232 1) $A19.95 (soft).

HAWKE'S LAW: The Politics of Mining and Aboriginal Land Rights in Australia by R. T. Libby. xxvii and 175 pages. University of Western Australia Press: Nedlands 1989 (ISBN 085564 301 1) $A25.00.

THE THIRD WORLD: States of Mind and Being edited by J. Norwine and A. Gonzales. 15 x 23 cm, xi and 275 pages. Unwin Hyman: Boston 1989 (ISBN 0 04 910121 8) $A39.95 (soft).

IRELAND: A Contemporary Geographical Perspective edited by R. W. G. Carter and A. J. Parker. 14 x 22 cm, xiv and 486 pages. Routledge: London 1989 (ISBN 0 415 00486 3) $A 120.00 (hard).  相似文献   

Evidence from polymict ureilite meteorites for a disrupted and re-accreted single ureilite parent asteroid gardened by several distinct impactors     

Hilary Downes  David W. Mittlefehldt  John W. Valley 《Geochimica et cosmochimica acta》2008,72(19):4825-4844

Ureilites are ultramafic achondrites that exhibit heterogeneity in mg# and oxygen isotope ratios between different meteorites. Polymict ureilites represent near-surface material of the ureilite parent asteroid(s). Electron microprobe analyses of >500 olivine and pyroxene clasts in several polymict ureilites reveal a statistically identical range of compositions to that shown by unbrecciated ureilites, suggesting derivation from a single parent asteroid. Many ureilitic clasts have identical compositions to the anomalously high Mn/Mg olivines and pyroxenes from the Hughes 009 unbrecciated ureilite (here termed the “Hughes cluster”). Some polymict samples also contain lithic clasts derived from oxidized impactors. The presence of several common distinctive lithologies within polymict ureilites is additional evidence that ureilites were derived from a single parent asteroid.In situ oxygen three isotope analyses were made on individual ureilite minerals and lithic clasts, using a secondary ion mass spectrometer (SIMS) with precision typically better than 0.2-0.4‰ (2SD) for δ¹⁸O and δ¹⁷O. Oxygen isotope ratios of ureilitic clasts fall on a narrow trend along the CCAM line, covering the range for unbrecciated ureilites, and show a good anti-correlation with mineral mg#. SIMS analysis identifies one ferroan lithic clast as an R-chondrite, while a second ferroan clast is unlike any known meteorite. An exotic enstatite grain is derived from an enstatite chondrite or aubrite, and another pyroxene grain with Δ¹⁷O of −0.4 ± 0.2‰ is unrelated to any known meteorite type.Ureilitic olivine clasts with mg#s < 85 are much more common than those with mg# > 85 which include the melt-inclusion-bearing “Hughes cluster” ureilites. Thus melt was present in regions of the parent ureilite asteroid with a bulk mg# > 85 when the asteroid was disrupted by impact, giving rise to two types of ureilites: common ferroan ones that were residual after melting and less common magnesian ones that were still partially molten when disruption occurred. One or more daughter asteroids re-accreted from the remnants of the mantle of the proto-ureilite asteroid. Polymict ureilite meteorites represent regolith that subsequently formed on the surface of a daughter asteroid, including impact-derived material from at least six different meteoritic sources.  相似文献   

Geochemistry, Petrogenesis and Geodynamic Relationships of Miocene Calc-alkaline Volcanic Rocks in the Western Carpathian Arc, Eastern Central Europe     

Harangi  Szabolcs; Downes  Hilary; Thirlwall  Matthew; Gmeling  Katalin 《Journal of Petrology》2007,48(12):2261-2287

We report major and trace element abundances and Sr, Nd andPb isotopic data for Miocene (16·5–11 Ma) calc-alkalinevolcanic rocks from the western segment of the Carpathian arc.This volcanic suite consists mostly of andesites and dacites;basalts and basaltic andesites as well as rhyolites are rareand occur only at a late stage. Amphibole fractionation bothat high and low pressure played a significant role in magmaticdifferentiation, accompanied by high-pressure garnet fractionationduring the early stages. Sr–Nd–Pb isotopic dataindicate a major role for crustal materials in the petrogenesisof the magmas. The parental mafic magmas could have been generatedfrom an enriched mid-ocean ridge basalt (E-MORB)-type mantlesource, previously metasomatized by fluids derived from subductedsediment. Initially, the mafic magmas ponded beneath the thickcontinental crust and initiated melting in the lower crust.Mixing of mafic magmas with silicic melts from metasedimentarylower crust resulted in relatively Al-rich hybrid dacitic magmas,from which almandine could crystallize at high pressure. Theamount of crustal involvement in the petrogenesis of the magmasdecreased with time as the continental crust thinned. A strikingchange of mantle source occurred at about 13 Ma. The basalticmagmas generated during the later stages of the calc-alkalinemagmatism were derived from a more enriched mantle source, akinto FOZO. An upwelling mantle plume is unlikely to be presentin this area; therefore this mantle component probably residesin the heterogeneous upper mantle. Following the calc-alkalinemagmatism, alkaline mafic magmas erupted that were also generatedfrom an enriched asthenospheric source. We propose that bothtypes of magmatism were related in some way to lithosphericextension of the Pannonian Basin and that subduction playedonly an indirect role in generation of the calc-alkaline magmatism.The calc-alkaline magmas were formed during the peak phase ofextension by melting of metasomatized, enriched lithosphericmantle and were contaminated by various crustal materials, whereasthe alkaline mafic magmas were generated during the post-extensionalstage by low-degree melting of the shallow asthenosphere. Thewestern Carpathian volcanic areas provide an example of long-lastingmagmatism in which magma compositions changed continuously inresponse to changing geodynamic setting. KEY WORDS: Carpathian–Pannonian region; calc-alkaline magmatism; Sr, Nd and Pb isotopes; subduction; lithospheric extension  相似文献