Government-Funded Deep Geophysical Surveys to Encourage Mineral Exploration: Results from the Western Australian “Exploration Incentives Scheme”     

Michael Dentith  Klaus Gessner  Simon Johnson  Ruth Murdie  Perla Pina-Varas  Jessica Spratt  Ian Tyler  Huaiyu Yuan 《《地质学报》英文版》2018,92(Z1):16-17

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The multiple chronological techniques applied to the Lake Suigetsu SG06 sediment core,central Japan     

Richard A. Staff  Takeshi Nakagawa  Gordon Schlolaut  Michael H. Marshall  Achim Brauer  Henry F. Lamb  Christopher Bronk Ramsey  Charlotte L. Bryant  Fiona Brock  Hiroyuki Kitagawa  Johannes van der Plicht  Rebecca L. Payne  Victoria C. Smith  Darren F. Mark  Alison Macleod  Simon P. E. Blockley  Jean‐Luc Schwenninger  Pavel E. Tarasov  Tsuyoshi Haraguchi  Katsuya Gotanda  Hitoshi Yonenobu  Yusuke Yokoyama  Suigetsu Project Members 《Boreas: An International Journal of Quaternary Research》2013,42(2):259-266

The varved sediment of Lake Suigetsu (central Japan) provides a valuable opportunity to obtain high‐resolution, multi‐proxy palaeoenvironmental data across the last glacial/interglacial cycle. In order to maximize the potential of this archive, a well‐constrained chronology is required. This paper outlines the multiple geochronological techniques being applied – namely varve counting, radiocarbon dating, tephrochronology (including argon–argon dating) and optically stimulated luminescence (OSL) – and the approaches by which these techniques are being integrated to form a single, coherent, robust chronology. Importantly, we also describe here the linkage of the floating Lake Suigetsu (SG06) varve chronology and the absolute (IntCal09 tree‐ring) time scale, as derived using radiocarbon data from the uppermost (non‐varved) portion of the core. This tie‐point, defined as a distinct (flood) marker horizon in SG06 (event layer B‐07–08 at 1397.4 cm composite depth), is thus derived to be 11 255 to 11 222 IntCal09 cal. years BP (68.2% probability range).  相似文献   

Acidic deposition impacts mediated by sulfur cycling in a coastal plain forest ecosystem     

Mark D. Morgan  Ralph E. Good  Henry G. Spratt Jr. Dr. 《GeoJournal》1988,17(2):183-187

Deposition in the New Jersey Pinelands was very acidic (pH=4.17) and contained high levels of SO₂ ⁻² based on bulk deposition measurementsfrom July 1984–July 1986. Streamwater over the same interval in undisturbed watersheds was less acidic (pH =4.52) and had proportionately less SO₄ ⁻². A preliminary alkalinity budget for undisturbed watersheds suggested that SO₄ ⁻² retention within Pinelands watersheds accounted for a large portion of the total alkalinity generated and thereby lessened the impact of acidic deposition on surface waters. The only process capable of explaining the retention of SO₄ ⁻² was microbial sulfate reduction in the extensive wetlands surrounding Pinelands streams which occurred at high rates.  相似文献   

The halo mass function from the dark ages through the present day     

Darren S. Reed  Richard Bower  Carlos S. Frenk  Adrian Jenkins  Tom Theuns 《Monthly notices of the Royal Astronomical Society》2007,374(1):2-15

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Statistical analysis of galaxy surveys – III. The non-linear clustering of red and blue galaxies in the 2dFGRS     

Darren J. Croton  Peder Norberg  Enrique Gaztañaga  Carlton M. Baugh 《Monthly notices of the Royal Astronomical Society》2007,379(4):1562-1570

We present measurements of the higher order clustering of red and blue galaxies as a function of scale and luminosity made from the two-degree field galaxy redshift survey (2dFGRS). We use a counts-in-cells analysis to estimate the volume-averaged correlation functions,     , as a function of scale up to the order of   p = 5  , and also the reduced void probability function. Hierarchical amplitudes are constructed using the estimates of the correlation functions:     . We find that (i) red galaxies display stronger clustering than blue galaxies at all orders measured; (ii) red galaxies show values of   S _p   that are strongly dependent on luminosity whereas blue galaxies show no segregation in   S _p   within the errors; this is remarkable given the segregation in the variance; (iii) the linear relative bias shows the opposite trend to the hierarchical amplitudes, with little segregation for the red sequence and some segregation for the blue; (iv) faint red galaxies deviate significantly from the 'universal' negative binomial reduced void probabilities followed by all other galaxy populations. Our results show that the characteristic colour of a galaxy population reveals a unique signature in its spatial distribution. Such signatures will hopefully further elucidate the physics responsible for shaping the cosmological evolution of galaxies.  相似文献   

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   

Risks of shifting baselines highlighted by anecdotal accounts of New Zealand's snapper (Pagrus auratus) fishery     

Darren M. Parsons  Mark A. Morrison  Alison B. MacDiarmid  Bruce Stirling  Phillip Cleaver  Ian W.G. Smith 《新西兰海洋与淡水研究杂志》2013,47(4):965-983

Anecdotal data sources may constitute an important component of the information available about an exploited species, as record keeping may not have occurred until after exploitation began. Here, we aimed to fill any gaps in the exploitative history of the sparid snapper (Pagrus auratus), using social and historical research methods. Social research consisted of interviews with recreational fishers, focusing on the most and largest snapper they had caught. In addition, the diary‐logs of two recreational fishers were analysed. Historical research consisted of investigation of old books, photos, archives and unpublished sources unconventional to fishery science. Interviews with fishers demonstrated no or weak trends in snapper abundance or size, and were likely impeded by a lack of ability to detect change in a fish stock that may still be considered abundant. The fishers’ perception of change, however, largely reflected recent experiences (last c. 10 years), when biomass is understood to have increased, and mostly did not consider experiences before the 1980s. Alternatively, diary‐logs of fisher catch rates produced a pattern that matched formal stock assessments of snapper biomass, suggesting declines in abundance up until the 1990s and an increase in biomass after that time. Historical research, although more qualitative, had the ability to investigate periods where formal records were not kept and described a fishery vastly different from the current one. Snapper were easily caught, in great abundance and in unusual locations. Localised depletion of snapper was first noticed in the early 20th century, despite spectacular catches of snapper occurring after that time. Snapper behaviour was also likely different, with visual sightings of snapper by onlookers a common occurrence. Although predictions from stock assessment models are consistent with that of the anecdotes listed here (i.e., high biomass in the past), these anecdotes are valuable as they explain lost biomass in a perspective meaningful to all. This perspective may be valuable for managers trying to consider the non‐financial value of a shared fishery but, if unrecognised, represents a shifting baseline.  相似文献   

Evolution of the mass function of dark matter haloes     

Darren Reed  Jeffrey Gardner  Thomas Quinn  Joachim Stadel  Mark Fardal  George Lake  Fabio Governato 《Monthly notices of the Royal Astronomical Society》2003,346(2):565-572

We use a high-resolution ΛCDM numerical simulation to calculate the mass function of dark matter haloes down to the scale of dwarf galaxies, back to a redshift of 15, in a  50 h ⁻¹ Mpc  volume containing 80 million particles. Our low-redshift results allow us to probe low-σ density fluctuations significantly beyond the range of previous cosmological simulations. The Sheth & Tormen mass function provides an excellent match to all of our data except for redshifts of 10 and higher, where it overpredicts halo numbers increasingly with redshift, reaching roughly 50 per cent for the  10¹⁰–10¹¹ M_⊙  haloes sampled at redshift 15. Our results confirm previous findings that the simulated halo mass function can be described solely by the variance of the mass distribution, and thus has no explicit redshift dependence. We provide an empirical fit to our data that corrects for the overprediction of extremely rare objects by the Sheth & Tormen mass function. This overprediction has implications for studies that use the number densities of similarly rare objects as cosmological probes. For example, the number density of high-redshift  ( z ≃ 6) QSOs  , which are thought to be hosted by haloes at 5σ peaks in the fluctuation field, are likely to be overpredicted by at least a factor of 50 per cent. We test the sensitivity of our results to force accuracy, starting redshift and halo-finding algorithm.  相似文献   

The 2dF Galaxy Redshift Survey: the b_J-band galaxy luminosity function and survey selection function     

Peder Norberg  Shaun Cole  Carlton M. Baugh  Carlos S. Frenk  Ivan Baldry  Joss Bland-Hawthorn  Terry Bridges  Russell Cannon  Matthew Colless  Chris Collins  Warrick Couch  Nicholas J. G. Cross  Gavin Dalton  Roberto De Propris  Simon P. Driver  George Efstathiou  Richard S. Ellis  Karl Glazebrook  Carole Jackson  Ofer Lahav  Ian Lewis  Stuart Lumsden  Steve Maddox  Darren Madgwick  John A. Peacock  Bruce A. Peterson  Will Sutherland  Keith Taylor 《Monthly notices of the Royal Astronomical Society》2002,336(3):907-931

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The 2dF Galaxy Redshift Survey: luminosity dependence of galaxy clustering     

Peder Norberg  Carlton M. Baugh  Ed Hawkins  Steve Maddox  John A. Peacock  Shaun Cole  Carlos S. Frenk  Joss Bland-Hawthorn  Terry Bridges  Russell Cannon  Matthew Colless  Chris Collins  Warrick Couch  Gavin Dalton  Roberto De Propris  Simon P. Driver  George Efstathiou  Richard S. Ellis  Karl Glazebrook  Carole Jackson  Ofer Lahav  Ian Lewis  Stuart Lumsden  Darren Madgwick  Bruce A. Peterson  Will Sutherland  Keith Taylor 《Monthly notices of the Royal Astronomical Society》2001,328(1):64-70

We investigate the dependence of the strength of galaxy clustering on intrinsic luminosity using the Anglo-Australian two degree field galaxy redshift survey (2dFGRS). The 2dFGRS is over an order of magnitude larger than previous redshift surveys used to address this issue. We measure the projected two-point correlation function of galaxies in a series of volume-limited samples. The projected correlation function is free from any distortion of the clustering pattern induced by peculiar motions and is well described by a power law in pair separation over the range     . The clustering of     galaxies in real space is well-fitted by a correlation length     and power-law slope     . The clustering amplitude increases slowly with absolute magnitude for galaxies fainter than M *, but rises more strongly at higher luminosities. At low luminosities, our results agree with measurements from the Southern Sky Redshift Survey 2 by Benoist et al. However, we find a weaker dependence of clustering strength on luminosity at the highest luminosities. The correlation function amplitude increases by a factor of 4.0 between     and −22.5, and the most luminous galaxies are 3.0 times more strongly clustered than L * galaxies. The power-law slope of the correlation function shows remarkably little variation for samples spanning a factor of 20 in luminosity. Our measurements are in very good agreement with the predictions of the hierarchical galaxy formation models of Benson et al.  相似文献