How do carbonate factories influence carbonate platform morphology? Exploring production−transport interactions with numerical forward modelling     

Daniel Sultana  Peter Burgess  Dan Bosence 《Sedimentology》2022,69(1):372-393

Understanding how carbonate factories influence platform evolution is either based on qualitative conceptual models or quantitative numerical stratigraphic forward models. This study establishes new production depth profiles for four Cenozoic carbonate factories and uses two-dimensional stratigraphic forward models to explore how interactions between sediment production and transport within carbonate systems influence carbonate platform development. Newly established production/depth profiles are used to model photozoan and heterozoan carbonate grain associations, and the associated carbonate producing factories, and results are compared with well-studied outcrop successions. Sediment production from photozoan and heterozoan grain associations is also equalized, so that the total sediment production is the same but the depth/production profiles retain their distinctly different form. Thus, the effect of the different production profiles can be assessed. Ramps form when sediment diffusional transport rates are high relative to production rates and flat-top steep-margin platforms form when sediment diffusional transport rates are low relative to production rates, whether they are photozoan or heterozoan grain associations. The control exerted by sediment production and transport is expressed as a sediment transport–production ratio where transport ratio is a diffusional sediment transport in two-dimensions and production ratio is the total sediment production rate which is the product of a production profile that varies in depth and laterally. The transport–production ratio is a key control on the evolution and geometry of carbonate platforms. This is the case with different production profiles (both euphotic and oligophotic) and in mixed grain-size and mixed transport-rate systems. Carbonate producing factories significantly influence the rate of sediment production, the depth distribution of sediment production (production profiles), as well as the type of grain sizes produced (influencing resistance to erosion). Thus, different types of carbonate grain associations, and the associated carbonate producing factories, can produce the critical differences between carbonate platform geometries.  相似文献   

Measurement of the Diurnal Variation of the OH Radical Concentration and Analysis of the Data by Modelling     

O. Forberich  T. Pfeiffer  M. Spiekermann  J. Walter  F. J. Comes  R. Grigonis  K. C. Clemitshaw  R. A. Burgess 《Journal of Atmospheric Chemistry》1999,33(2):155-181

Daily variations of the hydroxyl radical concentration have been measured during a campaign at the Weybourne Atmospheric Observatory (WAO) in June 1995. These measurements are compared with box model calculations, based on a slightly modified, second generation Regional Acid Deposition Model (RADM2). Results from eight days of the comparison are presented. A detailed analysis and discussion of the different source and sink terms is given for two days: Julian Day (JD) 170 (19 June, and 178 (27 June). In both cases excellent agreement between the measurements and the calculation is obtained, indicating that the model describes the OH chemistry sufficiently well. Furthermore, the analysis of these days demonstrate that JD 170 is dominated by the NOx catalysed OH production, whereas JD 178 is influenced by OH formation via ozone photolysis.  相似文献   

Modelling rates and distribution of subsidence due to dynamic topography over subducting slabs: is it possible to identify dynamic topography from ancient strata?   总被引：1，自引：0，他引：1  

Burgess  & Moresi 《Basin Research》1999,11(4):305-314

Dynamic topography formed over subducting oceanic lithosphere has been proposed as a mechanism to explain certain otherwise anomalous long-wavelength patterns of subsidence inferred from ancient strata. Forward modelling of mantle flow in response to a subducting slab predicts amplitudes and distributions of dynamic topography that may occur due to various subducting slab geometries and histories. Plotting calculated dynamic topographies at a point against time produces tectonic subsidence curves. These subsidence curves show features such as evolution from convex to concave shape, amplitudes up to ~2000 m, subsidence rates up to ~220 m Myr⁻¹, and a general decrease in subsidence amplitude away from the subduction zone, over a distance of ~2000 km. On many convergent continental margins, dynamic topography is likely to be superimposed on other subsidence mechanisms. In back-arc basins, subsidence due to dynamic topography should be distinguishable from that due to extensional tectonics based simply on the temporal subsidence evolution expressed in the subsidence curve shapes. In a foreland basin setting, comparing dynamic topography models with forward models of flexural loading suggest the two processes can generate similar temporal subsidence patterns, but that dynamic topography causes subsidence over significantly greater wavelengths. Matches between calculated subsidence due to dynamic topography and backstripped subsidence patterns from Upper Cretaceous strata of the Western Interior Basin, USA, support the hypothesis that a long-wavelength 'background subsidence' was caused by dynamic topography.  相似文献   

Measurement of bacterial water pollution and the log‐normal distribution (note)     

J. S. Burgess 《新西兰海洋与淡水研究杂志》2013,47(3):551-553

Examination of bacteriological, water pollution in river and nearshore ocean waters of southern Hawke Bay suggests that presentation and analysis of data expressed in terms of the median, as stipulated by New Zealand water pollution legislation, is often unsatisfactory. Data distributions are non‐normal and statistical comparisons over time and area difficult. These difficulties can be largely overcome by a simple log transformation of data.  相似文献   

Book reviews     

D. Burgess  F. D. Kahn  John Dyson  Patrick Roche  E. R. Priest  Edwin Budding  F. P. Keenan 《Astrophysics and Space Science》1994,222(1-2):263-270

  相似文献   

A Portable Matched-Field Processing System Using Passive Acoustic Time Synchronization     

Aaron M. Thode Peter Gerstoft William C. Burgess Karim G. Sabra Melania Guerra M. Dale Stokes Michael Noad Douglas H. Cato 《Oceanic Engineering, IEEE Journal of》2006,31(3):696-710

A portable matched-field processing (MFP) system for tracking marine mammals is presented, constructed by attaching a set of autonomous flash-memory acoustic recorders to a rope to form a four-element vertical array, or "insta-array." The acoustic data are initially time-synchronized by performing a matched-field global inversion using acoustic data from an opportunistic source, and then by exploiting the spatial coherence of the ocean ambient noise background to measure and correct for the relative clock drift between the autonomous recorders. The technique is illustrated by using humpback whale song collected off the eastern Australian coast to synchronize the array, which is then used to track the dive profile of the whale using MFP methods. The ability to deploy autonomous instruments into arbitrary "insta-array" geometries with conventional fishing gear may permit nonintrusive array measurements in regions currently too isolated, expensive, or environmentally hostile for standard acoustic equipment  相似文献   

Analytical studies of pile wandering during installation     

I. W. Burgess 《国际地质力学数值与分析法杂志》1979,3(1):49-62

In a previous paper it was established with very simple assumptions that piles might undergo a directional instability during placement, of a type more usually found in aerodynamic problems. The study is here extended to piles driven into soils whose shear strength and lateral reaction modulus can vary with depth. The analysis consists of a parametric study of the effect of linear variation of the soil parameters with depth on the critical lengths for instability, and a comparison of site evidence with the critical lengths obtained from a stepwise-constant representation of the variation of soil parameters with depth. The theory is shown to give very reasonable estimates of the depths at which major deviation starts, although there is a pressingneed for more detailed site and laboratory data.  相似文献   

REDD herrings or REDD menace: Response to Beymer-Farris and Bassett     

Neil D. Burgess  Shadrack Mwakalila  Pantaleo Munishi  Marion Pfeifer  Simon Willcock  Deo Shirima  Seki Hamidu  George B. Bulenga  Jason Rubens  Haji Machano  Rob Marchant 《Global Environmental Change》2013,23(5):1349-1354

Norwegian funded REDD+ projects in Tanzania have attracted a lot of attention, as has the wider REDD+ policy that aims to reduce deforestation and degradation and enhance carbon storage in forests of the developing countries. One of these REDD+ projects, managed by WWF Tanzania, was criticised in a scientific paper published in GEC, and consequently in the global media, for being linked to attempted evictions of communities living in the Rufiji delta mangroves by the Government of Tanzania, allegedly to make the area ‘ready for REDD’. In this response, we show how this eviction event in Rufiji mangroves has a history stretching back over 100 years, has nothing to do with REDD+ or any policy changes by government, and is not in any way linked to the work of any WWF project in Tanzania. We also outline some of the broader challenges faced by REDD+ in Tanzania.  相似文献   

Petrology, geochemistry, and age of low-Ti mare-basalt meteorite Northeast Africa 003-A: A possible member of the Apollo 15 mare basaltic suite     

Jakub Haloda  Patricie Týcová  Randy L. Korotev  Ray Burgess  Monika Jelenc  Pavel Gabzdyl 《Geochimica et cosmochimica acta》2009,73(11):3450-7225

Northeast Africa 003 (NEA 003) is a lunar meteorite found as a two paired stones (6 and 118 g) in Libya, 2000 and 2001. The main portion (∼75 vol%) of the 118 g meteorite, used for this study, (NEA 003-A) consists of mare-basalt and a smaller adjacent portion (∼25 vol%) is a basaltic breccia (NEA 003-B). NEA 003-A has a coarse-grained magmatic texture consisting mainly of olivine, pyroxene and plagioclase. The late-stage mineral association is composed mainly of elongated plagioclase, ilmenite, troilite, fayalite, Si-K-rich glass, apatite, and a rare SiO₂ phase. Other accessory minerals include ulvöspinel, chromite, and trace Fe-Ni metal. Olivine and pyroxene contain shock-induced fractures, and plagioclase is completely converted into maskelynite.The Fe/Mn values of the whole rock, olivines and pyroxenes, and the bulk-rock oxygen isotopic composition provide evidence for the lunar origin of NEA 003-A meteorite. This is further supported by the presence of Fe-Ni metal and the anhydrous mineral association.NEA 003-A is geochemically and petrographically distinct from previously described mare-basalt meteorites and is not paired with any of them. The petrography and major element composition of NEA 003-A is similar to the composition of low-Ti olivine mare basalts from Apollo 12 and olivine-normative basalts from Apollo 15. The NEA 003-A meteorite shows obvious geochemical similarities in trace elements contents with Apollo 15 olivine-normative basalts and could represent a yet unknown geochemically primitive member of the olivine-normative basalt series. The meteorite is depleted in rare earth elements (REE) and incompatible trace elements indicating a primitive character of the parental magma. The bulk-rock chemical composition demonstrates that the parent melt of NEA 003-A was not contaminated with KREEP components as a result of magma mixing or assimilation processes. Results of crystallization modelling and low minimum cooling rate estimates (∼0.07 °C/h) suggest that the parent melt of NEA 003-A crystallized in the lower part of a lava flow containing cumulate olivine (∼10%) and was probably derived from more primitive picritic magma by fractional crystallization processes.Sm-Nd dating yields an age of 3.09 ± 0.06 Ga which corresponds to the period of lower Eratosthenian lunar volcanic activity, and the near-chondritic ε_Nd value of −0.4 ± 0.3 indicates that the meteorite could be derived from a slightly enriched mantle source similar to the Apollo 15 green glasses. Ar-Ar step release results are inconsistent with Sm-Nd ages suggesting that NEA 003-A was exposed to one or more impact events. The most extensive event took place at 1.8 Ga and the shock intensity was likely between 28 and 45 GPa. The absence of solar Ar suggests that NEA 003-A has not been directly exposed at the lunar surface but the cosmic ray exposure age of 209 ± 6 Ma suggests that NEA 003-A resided in the upper regolith for part of its history.  相似文献   

HARP/ACSIS: a submillimetre spectral imaging system on the James Clerk Maxwell Telescope     

J. V. Buckle  R. E. Hills  H. Smith  W. R. F. Dent  G. Bell  E. I. Curtis  R. Dace  H. Gibson  S. F. Graves  J. Leech †  J. S. Richer  R. Williamson ‡  S. Withington  G. Yassin †  R. Bennett  P. Hastings  I. Laidlaw  J. F. Lightfoot  T. Burgess  P. E. Dewdney  G. Hovey  A. G. Willis  R. Redman  B. Wooff  D. S. Berry  B. Cavanagh  G. R. Davis  J. Dempsey  P. Friberg  T. Jenness  R. Kackley  N. P. Rees §  R. Tilanus  C. Walther  W. Zwart  T. M. Klapwijk  M. Kroug  T. Zijlstra 《Monthly notices of the Royal Astronomical Society》2009,399(2):1026-1043

This paper describes a new Heterodyne Array Receiver Program (HARP) and Auto-Correlation Spectral Imaging System (ACSIS) that have recently been installed and commissioned on the James Clerk Maxwell Telescope. The 16-element focal-plane array receiver, operating in the submillimetre from 325 to 375 GHz, offers high (three-dimensional) mapping speeds, along with significant improvements over single-detector counterparts in calibration and image quality. Receiver temperatures are ∼120 K across the whole band, and system temperatures of ∼300 K are reached routinely under good weather conditions. The system includes a single-sideband (SSB) filter so these are SSB values. Used in conjunction with ACSIS, the system can produce large-scale maps rapidly, in one or more frequency settings, at high spatial and spectral resolution. Fully sampled maps of     size can be observed in under 1 h.
The scientific need for array receivers arises from the requirement for programmes to study samples of objects of statistically significant size, in large-scale unbiased surveys of galactic and extra-galactic regions. Along with morphological information, the new spectral imaging system can be used to study the physical and chemical properties of regions of interest. Its three-dimensional imaging capabilities are critical for research into turbulence and dynamics. In addition, HARP/ACSIS will provide highly complementary science programmes to wide-field continuum studies and produce the essential preparatory work for submillimetre interferometers such as the Submillimeter Array (SMA) and Atacama Large Millimeter/Submillimeter Array (ALMA).  相似文献