Discussion and Reply: Shaping the Australian crust over the last 300 million years: Insights from fission track thermotectonic imaging and denudation studies of key terranes     

D. E. Leaman  B. P. Kohn  P. B. O'Sullivan  A. J. W. Gleadow  R. W. Brown  K. Gallagher 《Australian Journal of Earth Sciences》2013,60(4):645-650

Ellis Fjord is a small, fjord‐like marine embayment in the Vestfold Hills, eastern Antarctica. Modern sediment input is dominated by a biogenic diatom rain, although aeolian, fluvial, ice‐rafted, slumped and tidal sediments also make a minor contribution. In areas where bioturbation is significant relict glaciogenic sediments are reworked into the fine‐grained diatomaceous sediments to produce poorly sorted fine sands and silts. Where the bottom waters are anoxic, sediments remain unbioturbated and have a high biogenic silica component. Three depositional and non‐depositional facies can be recognised in the fjord: an area of non‐deposition around the shoreline; a relict morainal facies in areas of low sedimentation and high bioturbation; and a basinal facies in the deeper areas of the fjord.  相似文献   

Cenozoic fault control on ‘deep lead’ palaeoriver systems,Central Highlands,Victoria     

G. R. Holdgate  M. W. Wallace  S. J. Gallagher  R. B. Witten  B. Stats  B. E. Wagstaff 《Australian Journal of Earth Sciences》2013,60(3):445-468

Basaltic eruptions across the Central Highlands of Victoria have sealed in-place Early to middle Cenozoic palaeodrainage systems (also known as deep leads). The basal gravels of the deep leads have been mined extensively in the past for their rich placer-gold deposits. Detailed mapping of the distribution of all palaeorivers has been carried out using drilling results and modern aeromagnetic/radiometric surveys. The palaeochannel isopachs (including basalt and sediment) do not thicken in a modern downvalley direction. Instead, deeper depressions alternate with shallower areas. The variations in thickness, and parts of the palaeochannel courses, are controlled by a series of east-northeast-trending basement highs. The basement highs are caused by a set of east-northeast-trending (Otway Basin-style) faults visible on radar shuttle imagery in the Central Highlands. They have not previously been recognised in regional geological mapping. Most published fault trends are north – south oriented, parallel to the strike of the Palaeozoic basement rocks. Exceptions occur at Ballarat where there is an orthogonal east-northeast set mapped in underground quartz reef workings that show right-lateral strike-slip movements. The east-northeast faults show half-graben block-style rotational movement on basement, creating north- and south-facing fault scarps along the horst ridges. Where palaeochannels overlie the grabens, valleys broadened, infill thickens, and locally drainage directions may change. When the drainage cuts through the horsts, steeper incised valleys result, and this is where, in the historical past, some gold leads were ‘lost’. The initial timing of the block movement pre-dates at least the Early Oligocene to Late Miocene ages of the basal palaeovalley sediments, as shown by revised palynological dating. In places, the modern drainage divide coincides with east-northeast-trending faults. In the Ballarat area, an earlier divide accentuated by the aeromagnetic palaeodrainage mapping occurs up to 25 km south and appears to pre-date the earliest basalt flows at around 7.0 Ma. This evidence suggests the divide can change position through time by differential movements along east-northeast faults and transferral of maximum uplift to adjacent blocks.  相似文献   

Multifractal Properties of Evolving Active Regions     

P. A. Conlon  P. T. Gallagher  R. T. J. McAteer  J. Ireland  C. A. Young  P. Kestener  R. J. Hewett  K. Maguire 《Solar physics》2008,248(2):297-309

Magnetohydrodynamic turbulence is thought to be responsible for producing complex, multiscale magnetic field distributions in solar active regions. Here we explore the multiscale properties of a number of evolving active regions using magnetograms from the Michelson Doppler Imager (MDI) on the Solar and Heliospheric Observatory (SOHO). The multifractal spectrum was obtained by using a modified box-counting method to study the relationship between magnetic-field multifractality and region evolution and activity. The initial emergence of each active region was found to be accompanied by characteristic changes in the multifractal spectrum. Specifically, the range of multifractal structures (D _div) was found to increase during emergence, as was their significance or support (C _div). Following this, a decrease in the range in multifractal structures occurred as the regions evolved to become large-scale, coherent structures. From the small sample considered, evidence was found for a direct relationship between the multifractal properties of the flaring regions and their flaring rate.  相似文献   

Reply to comment regarding the ICE-hypothesis     

S.B. Nielsen  K. Gallagher  D.L. Egholm  O.R. Clausen  M. Summerfield 《Journal of Geodynamics》2009,48(2):101-106

In this reply, we address the issues raise by the comment of Lidmar-Bergström and Bonow [Lidmar-Bergström, K., Bonow, J., 2009. Hypotheses and observations on the origin of the landscape of southern Norway – a reply regarding the isostasy–climate–erosion hypothesis by Nielsen et al., 2008. Journal of Geodynamics, in press]. We reject them and maintain all our suggestions regarding western Scandinavia unaltered.  相似文献   

Biostratigraphy and macroinvertebrate palaeontology of the petroleum-rich Belfast Mudstone (Sherbrook Group, uppermost Turonian to mid-Santonian), Otway Basin, southeastern Australia     

Jeffrey D. Stilwell  Stephen J. Gallagher 《Cretaceous Research》2009,30(4):873-884

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Centimeter-Level Positioning of a U. S. Coast Guard Buoy Tender   总被引：1，自引：1，他引：0  

David B. Zilkoski  J. Don D'Onofrio  Rudolf J. Fury  Curtis L. Smith  Lloyd C. Huff  Barry J. Gallagher 《GPS Solutions》1999,3(2):53-65

With the availability of high-accuracy, differential global positioning system (GPS) results in real-time, there is a new opportunity to use GPS to accurately measure a marine vessel's dynamic draft (settlement and squat) and 3D attitude (roll, pitch, and heading). The National Geodetic Survey (NGS) and the Coast Survey (CS), offices of the National Ocean Service (NOS), National Oceanic and Atmospheric Administration (NOAA), propose to transfer this technology to the shipping industry. The overall goal of this project is to provide the position of a vessel's keel in real time to within 10 cm (about 4 inches) relative to the bottom of the shipping channel. In support of this phase of the project, there were three meetings hosted by the Port of Oakland, California and NOS to discuss the real-time positioning of vessels project. On December 3 and 4, 1996, CS, NGS, Trimble Navigation Ltd., and the U. S. Coast Guard (USCG) performed GPS tests on a USCG buoy-tender ship. GPS data were used to compute the vessel's dynamic draft and 3D attitude. During the test, five receivers continually collected data; one receiver was located at a base station on the USCG pier on Yerba Buena Island, and four were on the ship: two on the stern and two on the bow. CS installed a TSS-335B vertical reference unit (to measure heave, pitch, and roll) in the engine room of the ship. NOS processed the GPS data and computed the vessel's dynamic draft and 3D attitude. The results indicate that the linear equivalent to the vessel's dynamic draft and 3D attitude were accurate to the 10-cm level using GPS. It was also demonstrated how a ship can be used to measure local water-level changes and actual water-level values everywhere it travels. ? 1999 John Wiley & Sons, Inc.  相似文献   

Subsidence, sedimentation and sea-level changes in the Eromanga Basin, Australia     

KERRY Gallagher  KURT Lambeck 《Basin Research》1989,2(2):115-131

Abstract The Jurassic-Cretaceous subsidence history of the Eromanga Basin, a large intracratonic sedimentary basin in central eastern Australia, has been examined using standard backstripping techniques, allowing for porosity reduction by compaction and cementation. Interpretation of the results suggests that during the Jurassic the basin was subsiding in a manner consistent with the exponentially decreasing form predicted by simple thermally based tectonic models. By the Early Cretaceous, the rate of subsidence was considerably higher than that expected from such models and nearly half of the total sediment thickness was deposited over the final 20 Myr of the basin's 95 Myr Mesozoic depositional history. The Early Cretaceous also marks the first marine incursion into the basin, consistent with global sea-level curves. Subsequently, however, the sediments alternate between marine and non-marine, with up to 1200 m of fluvial sediments being deposited, and this was followed by a depositional hiatus of about 50 Myr in the Late Cretaceous. This occurred at a time when global sea-level was rising to its peak. A model is presented which is consistent with the rapid increase in tectonic subsidence rate and the transgressive-regressive nature of the sediments. The model incorporates a sediment influx which is greater than that predicted by the thermally based tectonic models implied by the Jurassic subsidence history. The excess sedimentation results in the basin region attaining an elevation which exceeds that of the contemporary sea-level, and thereby giving the appearance of a regression. The present day elevation of the region predicted by the model is about 100–200 m above that observed. This discrepancy may arise because the primary tectonic subsidence is better represented by a linear function of time rather than an exponentially decreasing form.  相似文献   

Effects of β-naphthoflavone on hepatic biotransformation and glutathione biosynthesis in largemouth bass (Micropterus salmoides)     

Erin M. Hughes  Evan P. Gallagher   《Marine environmental research》2004,58(2-5):675

We are investigating the effects of in vivo exposure of prototypical enzyme inducing agents on hepatic biotransformation enzyme expression in largemouth bass (Micropterus salmoides), a predatory game fish found throughout the United States and Canada. The current study targeted those genes involved in biotransformation and oxidative stress that may be regulated by Ah-receptor-dependent pathways. Exposure of bass to β-naphthoflavone (β-NF, 66 mg/kg, i.p.) elicited a 7–9-fold increase in hepatic microsomal cytochrome P4501A-dependent ethoxyresorufin O-deethylase (EROD) activities, but did not affect cytosolic GST catalytic activities toward 1-chloro-2,4-dinitrobenzene (CDNB) or 5-androstene-3,17-dione (ADI). Glutathione S-transferase A (GST-A) mRNA expression exhibited a transient, but non-significant increase following exposure to β-NF, and generally tracked the minimal changes observed in GST–CDNB activities. Expression of the mRNA encoding glutamate-cysteine ligase catalytic subunit (GCLC), the rate-limiting enzyme in glutathione (GSH) biosynthesis, was increased 1.7-fold by β-NF. Changes in GCLC mRNA expression were paralleled by increases in intracellular GSH. In summary, largemouth bass hepatic CYP1A-dependent and GSH biosynthetic pathways, and to a lesser extent GST, are responsive to exposure to β-NF.  相似文献   

Conjugation of 4-hydroxynonenal by largemouth bass (Micropterus salmoides) glutathione S-transferases     

Pham RT  Gardner JL  Gallagher EP 《Marine environmental research》2002,54(3-5):291-295

The glutathione S-transferases (GST) are a major group of conjugative enzymes involved in the detoxification of electrophilic compounds and products of oxidative stress. We have previously described the kinetics of hepatic GST conjugation in largemouth bass using a variety of synthetic GST reference substrates. In the present study, we investigated the ability of largemouth bass hepatic GSTs to conjugate 4-hydroxynon-2-enal (4HNE), a mutagenic and cytotoxic alpha-beta-unsaturated aldehyde produced during oxidative injury. Hepatic cytosolic fractions from largemouth bass rapidly catalyzed GSH-dependent 4HNE conjugation, with the rate of GST-4HNE conjugation in bass liver exceeding those of several other mammalian and aquatic species. No apparent sex-related differences in GST-4HNE activity were observed among adult bass. SDS-PAGE and Western blotting analysis of GSH affinity-purified bass liver cytosolic GST revealed the presence of two major GST subunits of approximately 30 and 27 KDa that exhibited slight cross-reactivity when probed with a rat alpha class GST antibody, but not to rat mu, pi or theta class GST. The rapid conjugation of 4HNE by hepatic GST suggests an important role for GSTs in protecting against peroxidation of polyunsaturated fatty acids in bass liver.  相似文献   

NDEA PROPOSALS PREPARATION AND SUCCESSFUL FACTORS FOR INSTITUTES     

James W. Gallagher 《The Professional geographer》1966,18(1):40-42

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