UTS site search

Professor Greg Skilbeck


Professor Greg Skilbeck has been on the academic staff of the University of Technology Sydney, since 1987 and is currently assistant Deputy Vice Chancellor (Research), in the Office of the Deputy Vice Chancellor.  He is also Professor of Earth Sciences in the Faculty of Science and is a former Associate Dean Research in Science (2007-2014), and Head of Department (Environmental Science) (1996-2006).

Prof Skilbeck is a sedimentary geologist with expertise in facies analysis, sedimentary petrology, diagenesis and physical properties, sedimentary basin analysis, and marine geoscience and palaeoclimate studies. After graduating from Sydney University in the 1980's, he was employed in the Australian petroleum exploration industry where he was involved in exploration in the Cooper Basin and Northwest Shelf. He has experience with 2D and 3D seismic and sequence stratigraphic interpretation and qualitative and quantitative geophysical log analysis. In 1994 Greg carried out a petroleum evaluation project in the PRC for the Earth Science Resources Institute (University of South Carolina), which involved assessment of the extensional basins along the convergent Pacific margin of China.

Over the past 25 years his research interests have ranged from sedimentation associated with convergent margins, specifically in reconstructing basin forming-processes from stratigraphic sequences, to palaeooceanography and climate studies. In order to provide modern constraints on these studies, he participated in the 1995 Mediterranean tectonics leg of the Ocean Drilling Program (Leg 161).

Professor Skilbeck is currently investigating Late Quaternary palaeoclimatic and sea level variability from lake sediments in NSW and Hawai’i and oceanic sediments in the central and eastern Pacific, with a particular emphasis on reconstructing palaeo-El Nino. He participated in the eastern tropical Pacific deep biosphere leg of the ODP in 2002, sailing as a physical properties specialist. He is an International Atomic Energy Agency CRP Project Leader on the use of radioisotopes in the study of El Nino (2005-2009).  He has participated in four scientific research voyages, 2 on the JOIDES Resolution (1996 and 2002), one on the Marion DuFresne (2006) as an instructor on the University of the Sea, and one to Macquarie Island on the Aurora Australis (2007).


Employment History:

2015-         : Assistant Deputy Vice Chancellor (Research), UTS

2014- 2015: Executive Director, Research Strategy & International Research, UTS

2007-2014: Associate Dean (Research & Development), Faculty of Science, UTS
2004-2006: Professor and Head of Department (Environmental Sciences, UTS)

2003-2006: Conjoint Associate Professor (University of Newcastle)
1998-2004: A/Professor and Head of Department (Environmental Sciences, UTS)
1996-1997: Head of Department (Applied Geology, UTS)
1991-1997: Senior Lecturer (UTS)
1988-1991: Lecturer (UTS)
1984-1987: Exploration Geoscientist (Santos Ltd, Adelaide)
1981-1984: Projects Officer (Earth Resources Foundation, Univ. Sydney)
1979-1981: Tutor (Geology & Geophysics, University of Sydney)

Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-ansi-language:EN-US; mso-fareast-language:EN-US;}

Membership of Professional Bodies:

NSW Divisional Chair 1995-96, committee 2002-2003, 2006- ;
National Executive Committee 2000-2004.
Convenor, 15th Australian Geological Convention (Sydney 2000)
SA Divisional Committee, 1985-86.

Consulting and Advisory Committees:

  • AINSE Environmental Committee (Member 2006-2009)
Chair (2008-2009)
  • Australian Institute of Nuclear Science and Technology (AINSE) Councillor for UTS (2005 - )
  • Review Sydney University Marine Science (External Member) (2007)
  • Review University of Newcastle Science Undergraduate Coursework Programs Committee (External Member) (2006)
  • PacRim (Australia, Canada, Taiwan, Korea Consortium) Representative, ODP Scientific Measurements Panel (1999-2000)
  • Australian ODP Scientific Committee (Member 1999-2003)
  • NSW Board of Studies K-12 Science Curriculum Committee (Member 1990-1994)
  • 2 Unit Geology Examinations Committee (Member 1989-1994)
Chair (1992)

Editorial and Other Refereeing Work:

Image of Greg Skilbeck
Assistant Deputy Vice-Chancellor (Research), Deputy Vice-Chancellor (Research)
Core Member, Centre for Environmental Sustainability
BSc (Hons) (Syd), PhD (Syd)
+61 2 9514 1760

Research Interests

Following on from work initiated during Leg 161, in 1997 I commenced a research program on sedimentary evolution and palaeoclimate archives of the Myall Lakes system (eastern NSW), supported by an ARC small grant and Australian Nuclear Science Institute support for 14C dating. The project has now evolved into of a larger study of south, central and eastern Pacific palaeoclimate records and recent sea level history. Over the intervening period co-workers and I have collected, logged and sampled ~40 cores from Myall and Tuggerah Lakes and Fullerton Cove (NSW), from Barbers Point (Oahu, Hawaii) and most recently from the Peru continental margin during Leg 201 of the ODP in which I participated as a physical properties specialist. Project support has come from internal UTS and the ARC (3 grants) in Australia, and through Sea Grant and NSF funds. The overall project, which involves international co-operation with scientists from the USA, UK and Italy, has started to yield exciting, important and significant results.

Palaeo El Nino: Study of laminated sediments from the Peru continental margin. Cores collected during Leg 201 of the ODP. Currently analysing early Post Glacial section (in Hole 1227B) and Holocene sections (in Holes 1228B and 1229E). The work is included as a project in the International Atomic Energy Agency (UNESCO) Co-ordinated Research Project on the Nuclear and Isotope Studies of the El Nino Phenomenon Project K41009, 2004-2009). Funded by Australian ODP, IAEA, AINSE grants.

Eastern Australian Palaeoclimate and Environmental Archives: Study of eastern Australian temperate estuary sediments from Tuggerah Lakes to Myall Lakes. Investigating sedimentation history and palaeoclimate history of region. Funded by ARC Discovery Project DP0209388 (2002-2004).

Can supervise: Yes

In my 20+ years at UTS I have been involved in teaching a multitude of both geological and environmental science subjects (see below). In addition, I have been Course Director of the following degree programs - B App Sci (Applied Geology), BSc (Earth and Environmental Sciences), BSc (Marine Biology), BSc (Applied Geology, Honours):

Undergraduate Teaching:
Current Teaching:

  • 91149 Geological Processes (6 credit points, 2nd year)
Past Teaching:
  • 91107 The Biosphere (6 credit points1, 1st year subject)
  • 66513 Marine Geoscience (Online distance mode) (6 credit points1, elective)
  • 91126 Coral Reef Ecosystems (6 credit points, elective)
  • Earth Sciences 1 (and multiple iterations thereof including Introduction to Earth Sciences, Geology 1) (all 6 credit points1, 1st year) (1993-2007)
  • Geological Mapping (4 credit points, 1st year)
  • Basin Analysis (4 credit points, 2nd year)
  • Fossil Fuels (4 credit points, 2nd year)
  • Advanced Fossil Fuels (4 credit points, 3rd year)
  • Engineering and Environmental Geology (4 credit points, 3rd year)
  • Exploration Geophysics (4 credit points, 3rd year)
  • Surface Dynamics and People (6 credit points, 3rd year)
  • Surface Processes and Products (6 credit points, 2nd year)
  • Geodynamics (4 credit points, 2nd year)
  • Earth Resources (6 credit points, 3rd year)
  • Fold Belts and Cratons (6 credit points, 2nd year)
  • Quaternary Geology and Palaeoclimate Studies (6 credit points, elective)
  • GIS and Remote Sensing (6 credit points, 2nd year)
  • Catchment Ecosystems (6 credit points, 1st year)
  • Industrial Training Sandwich Program

Honours Coursework Teaching:
  • Advanced Clastic Basin Analysis (3 credit points, SUCOGG2 Hons subject)
  • Interpretation of 2D & 3D Seismic Reflection Data (3 credit points, SUCOGG Hons subject, with Derecke Palmer, UNSW)

Post Graduate Teaching: (all by research)
  • Honours
  • MSc
  • PhD

1 credit point ~ 1 hour per week, for 13 to 14 weeks; approximately ¼ of a full time undergraduate load
2 SUCOGG = Sydney Universities Consortium of Geology and Geophysics. A joint initiative between 4 Sydney metropolitan universities (UTS, Macquarie, U Sydney and UNSW) inter alia to jointly teach honours level subjects.


d'Hondt, S., Jorgensen, B.B., Miller, J., Aiello, I.W., Bekins, B., Blake, R., Cragg, B., Cypionka, H., Dickens, G., Ferdelman, T.G., Ford, K.H., Gettemy, G.L., Guerin, G., Hinrichs, K., Holm, N., House, C.H., Inagaki, F., Meister, P., Mitterer, R.M., Naehr, T.H., Niitsuma, S., Parkes, R.J., Schippers, A., Skilbeck, G., Smith, D., Spivack, A., Teske, A.P. & Wiegel, J. 2003, Proceedings of the Ocean Drilling Program, National Science Foundation, Canada.


Yunusa, I.A., Veeragathipillai, M., Burchett, M., Eamus, D. & Skilbeck, G. 2007, 'Utilisation of coal combustion products in agriculture' in Gurba, L., Heidrich, C. & Ward, C. (eds), Coal Combustion Products Handbook, Cooperative Research Centre for Coal in Sustainable Development, Australia, pp. 374-409.
Skilbeck, G. & Howard, W. 2005, 'The Future of Scientific Drilling in Australia' in Baker, E. & Keene, J. (eds), Full Fathom Five: 15 Years of Australian Involvement in the Ocean Drilling Program, Australasian ODP Publications, Sydney, Australia, pp. 57-63.
The aim of this contribution is to make a case for the ongoing participation of Australia in the exploration and understanding of te global oceans. It is relatively easy for scientists to make such an argument on scientific grounds alone, and some of the more important insights to our current understanding of the Earth provided by 35 years of ocean drilling are reviewed below.
Skilbeck, G., Korsch, R. & He, F. 2004, 'Petrography and whole rock geochemistry of clastic sedimentary rocks from the Cranky Corner Basin' in Facer, R.A. & Foster, C.B. (eds), Geology of the Cranky Corner Basin, NSW Department of Mineral Resources and Geoscience Australia, Sydney, Australia, pp. 65-105.
Skilbeck, C.G. & Tribble, J.S. 1999, 'Description, classification, and origin of Upper Pliocene-Holocene marine sediments in the Alboran Basin', pp. 83-97.
Upper Pliocene-Holocene deep marine sediments from four sites in the Alboran Basin drilled during Ocean Drilling Program Leg 161 are remarkably uniform in their overall composition and texture despite the geographic isolation of the sites. The sediments are predominantly structureless to burrowed clays and silty clays, in which the main components are calcareous nannofossils, clay, and sand-sized foraminifers. Quartz and feldspar of detrital origin form a minor common fraction. One hundred and sixty samples were analyzed by wet sieving for grain-size distribution and by X-ray diffraction for mineralogy. The textural data confirm visual descriptions of the shipboard scientists, and all samples contain over 87% clay and fine silt (<20-?m grain-size diameter) and, on average, only 3%-4% sand. The proportions of a suite of 14 minerals (quartz, albite, bytownite, orthoclase, chlorite, illite, kaolinite, muscovite, talc, halite, pyrite, gypsum, dolomite, and calcite) were quantified using Siroquant software, and the results confirm the dominant carbonate composition. Downhole distribution of the proportions of quartz, which was used to infer detrital input, 'clay' (all phyllosilicate minerals regardless of origin), and total carbonate (calcite + dolomite) for each of the four holes examined are variable and broadly cyclic, but show no clear trends when compared either with each other or with sedimentation rate. Between-hole temporal correlation of cycles in both the <20-?m carbonate fraction (nannofossils) and the >63-?m carbonate fraction (foraminifers) is reasonably strong at frequencies of ~500 ka for the former and 750 ka for the latter. This suggests a regional control on carbonate deposition, which is interpreted to most probably be climatic in origin. In contrast, cycles in quartz distribution cannot be regionally correlated for any of the grain-size fractions, and sources cannot be unequivocally resolved. However, we propose that the detrital material has been ...


Yunusa, I.A., Veeragathipillai, M., Skilbeck, G. & Eamus, D. 2008, 'Amelioration of soil physical properties and enhancement of root growth with coal fly ash.', Soil â the living skin of the planet earth, Soil â the living skin of the planet earth, Australia and New Zealand joint Soil Science Societies, Massey University, Palmerston North, New Zealand, pp. 1-3.
Yunusa, I.A., Veeragathipillai, M., Burchett, M., Skilbeck, G. & Eamus, D. 2007, 'Australian fly-ashes as an agronomic resource: progress and new opportunities', Contamination Clean-up 07, Adelaide, Australia.
Yunusa, I., Manoharan, V., Eamus, D. & Skilbeck, G. 2007, 'Economic and environmental advantages of using fly ash as a soil amendment in agronomy', ENVIRONMENTAL SCIENCE, ECOSYSTEMS AND DEVELOPMENT, pp. 294-302.
View/Download from: UTS OPUS
Yunusa, I.A., Eamus, D., De Silva, D.L., Murray, B., Burchett, M., Skilbeck, G. & Heidrich, C. 2005, 'Prospects for coal-ash in the management of Australian soils', World of Coal Ash Proceedings, World of Coal Ash 2005, Coal ash Association and the University of Kentucky's Centre for Applied Energy Research, Lexington, USA, p. CD ROM.

Journal articles

Macreadie, P.I., Rolph, T.C., Schröder-Adams, C., Boyd, R. & Skilbeck, C.G. 2015, 'Holocene record of Tuggerah Lake estuary development on the Australian east coast: Sedimentary responses to sea-level fluctuations and climate variability', GeoResJ, vol. 5, pp. 57-73.
View/Download from: UTS OPUS or Publisher's site
&copy; 2015 The Authors. We investigated the Holocene palaeo-environmental record of the Tuggerah Lake barrier estuary on the south-east coast of Australia to determine the influence of local, regional and global environmental changes on estuary development. Using multi-proxy approaches, we identified significant down-core variation in sediment cores relating to sea-level rise and regional climate change. Following erosion of the antecedent land surface during the post-glacial marine transgression, sediment began to accumulate at the more seaward location at ~8500. years before present, some 1500. years prior to barrier emplacement and ~4000. years earlier than at the landward site. The delay in sediment accumulation at the landward site was a consequence of exposure to wave action prior to barrier emplacement, and due to high river flows of the mid-Holocene post-barrier emplacement. As a consequence of the mid-Holocene reduction in river flows, coupled with a moderate decline in sea-level, the lake experienced major changes in conditions at ~4000. years before present. The entrance channel connecting the lake with the ocean became periodically constricted, producing cyclic alternation between intervals of fluvial- and marine-dominated conditions. Overall, this study provides a detailed, multi-proxy investigation of the physical evolution of Tuggerah Lake with causative environmental processes that have influenced development of the estuary.
Macreadie, P.I., Trevathan-Tackett, S.M., Skilbeck, C.G., Sanderman, J., Curlevski, N., Jacobsen, G. & Seymour, J.R. 2015, 'Losses and recovery of organic carbon from a seagrass ecosystem following disturbance', Proceedings of the Royal Society B: Biological Sciences, vol. 282, no. 1817.
View/Download from: Publisher's site
&copy; 2015, The Author(s) Published by the Royal Society. All rights reserved. Seagrasses areamong the Earth'smost efficient and long-termcarbon sinks, but coastal development threatens this capacity. We report new evidence that disturbance to seagrass ecosystems causes release of ancient carbon. In a seagrass ecosystem that had been disturbed 50 years ago, we found that soil carbon stocks declined by 72%, which, according to radiocarbon dating, had taken hundreds to thousands of years to accumulate.Disturbed soils harboured different benthic bacterial communities (according to 16S rRNA sequence analysis), with higher proportions of aerobic heterotrophs compared with undisturbed. Fingerprinting of the carbon (via stable isotopes) suggested that the contribution of autochthonous carbon (carbon produced through plant primary production) to the soil carbon pool was less in disturbed areas compared with seagrass and recovered areas. Seagrass areas that had recovered from disturbance had slightly lower (35%) carbon levels than undisturbed, but more than twice as much as the disturbed areas,which is encouraging for restoration efforts. Slow rates of seagrass recovery imply the need to transplant seagrass, rather than waiting for recovery via natural processes. This study empirically demonstrates that disturbance to seagrass ecosystems can cause release of ancient carbon, with potentially major global warming consequences.
Kelleway, J.J., Saintilan, N., Macreadie, P.I., Skilbeck, C.G., Zawadzki, A. & Ralph, P.J. 2015, 'Seventy years of continuous encroachment substantially increases 'blue carbon' capacity as mangroves replace intertidal salt marshes', Global Change Biology.
View/Download from: Publisher's site
&copy; 2015 John Wiley & Sons Ltd. Shifts in ecosystem structure have been observed over recent decades as woody plants encroach upon grasslands and wetlands globally. The migration of mangrove forests into salt marsh ecosystems is one such shift which could have important implications for global 'blue carbon' stocks. To date, attempts to quantify changes in ecosystem function are essentially constrained to climate-mediated pulses (30 years or less) of encroachment occurring at the thermal limits of mangroves. In this study, we track the continuous, lateral encroachment of mangroves into two south-eastern Australian salt marshes over a period of 70 years and quantify corresponding changes in biomass and belowground C stores. Substantial increases in biomass and belowground C stores have resulted as mangroves replaced salt marsh at both marine and estuarine sites. After 30 years, aboveground biomass was significantly higher than salt marsh, with biomass continuing to increase with mangrove age. Biomass increased at the mesohaline river site by 130 &plusmn; 18 Mg biomass km-2 yr-1 (mean &plusmn; SE), a 2.5 times higher rate than the marine embayment site (52 &plusmn; 10 Mg biomass km-2 yr-1), suggesting local constraints on biomass production. At both sites, and across all vegetation categories, belowground C considerably outweighed aboveground biomass stocks, with belowground C stocks increasing at up to 230 &plusmn; 62 Mg C km-2 yr-1 (&plusmn; SE) as mangrove forests developed. Over the past 70 years, we estimate mangrove encroachment may have already enhanced intertidal biomass by up to 283 097 Mg and belowground C stocks by over 500 000 Mg in the state of New South Wales alone. Under changing climatic conditions and rising sea levels, global blue carbon storage may be enhanced as mangrove encroachment becomes more widespread, thereby countering global warming.
Macreadie, P.I., Rolph, T.C., Boyd, R., Schroeder-Adams, C.J. & Skilbeck, C.G. 2015, 'Do ENSO and Coastal Development Enhance Coastal Burial of Terrestrial Carbon?', PLOS ONE, vol. 10, no. 12.
View/Download from: Publisher's site
Yunusa, I.A.M., Loganathan, P., Nissanka, S.P., Manoharan, V., Burchett, M.D., Skilbeck, C.G. & Eamus, D. 2014, 'Application of coal fly ash in agriculture: A strategic perspective', Critical Reviews in Environmental Science and Technology, vol. 42, no. 6, pp. 559-600.
View/Download from: UTS OPUS or Publisher's site
Copyright &copy; 2012 Crown copyright. Fly ash is a major waste of coal-power generation and its management is a major environmental and economic challenge, and it will become even more critical with a projected increase in the reliance on coal for power generation. The authors discuss how the unique physicochemical properties of ash can be strategically employed to ameliorate acidity and sodicity, and physical and fertility constraints, in agricultural soils. They show that with careful selection of ash type and methods and rates of application, mutually compatible with the soil and crop type, the often reported phytotoxicity due to high concentrations of certain trace metals can be avoided while maintaining the quality of produce and minimizing risk to the environment. Specific examples are presented to demonstrate where it is economical to use fly ash as a low-cost alternative to certain fertilizers and liming materials on farms. The authors also propose criteria for the selection of ash and for regulatory parameters that would ensure the safe and routine utilization of ash in plant production systems.
Kelaher, B.P., Bishop, M.J., Potts, J., Scanes, P. & Skilbeck, G. 2013, 'Detrital diversity influences estuarine ecosystem performance', Global Change Biology, vol. 19, no. 6, pp. 1909-1918.
View/Download from: UTS OPUS or Publisher's site
Global losses of seagrasses and mangroves, eutrophication-driven increases in ephemeral algae, and macrophyte invasions have impacted estuarine detrital resources. To understand the implications of these changes on benthic ecosystem processes, we tested the hypotheses that detrital source richness, mix identity, and biomass influence benthic primary production, metabolism, and nutrient fluxes. On an estuarine muddy sandflat, we manipulated the availability of eight detrital sources, including mangrove, seagrass, and invasive and native algal species that have undergone substantial changes in distribution. Mixes of these detrital sources were randomly assigned to one of 12 treatments and dried detrital material was added to seventy-two 0.25 m2 plots (n = 6 plots). The treatments included combinations of either two or four detrital sources and high (60 g) or low (40 g) levels of enrichments. After 2 months, the dark, light, and net uptake of NH4 +, dissolved inorganic nitrogen, and the dark efflux of dissolved organic nitrogen were each significantly influenced by the identity of detrital mixes, rather than detrital source richness or biomass. However, gross and net primary productivity, average oxygen flux, and net NOX and dissolved inorganic phosphorous fluxes were significantly greater in treatments with low than with high detrital source richness. These results demonstrate that changes in detrital source richness and mix identity may be important drivers of estuarine ecosystem performance. Continued impacts to estuarine macrophytes may, therefore, further alter detritus-fueled productivity and processes in estuaries. Specific tests that address predicted future changes to detrital resources are required to determine the consequences of this significant environmental problem. &copy; 2013 Blackwell Publishing Ltd.
Macreadie, P.I., Allen, K., Kelaher, B.P., Ralph, P.J. & Skilbeck, C.G. 2012, 'Paleoreconstruction of estuarine sediments reveal human-induced weakening of coastal carbon sinks', Global Change Biology, vol. 18, no. 3, pp. 891-901.
View/Download from: UTS OPUS or Publisher's site
Human activities in coastal areas frequently cause loss of benthic macrophytes (e.g. seagrasses) and concomitant increases in microalgal production through eutrophication. Whether such changes translate into shifts in the composition of sediment detritus is largely unknown, yet such changes could impact the role these ecosystems play in sequestrating CO 2. We reconstructed the sedimentary records of cores taken from two sites within Botany Bay, Sydney - the site of European settlement of Australia - to look for human-induced changes in dominant sources of detritus in this estuary. Cores covered a period from the present day back to the middle Holocene (~6000 years) according to 210Pb profiles and radiocarbon ( 14C) dating. Depositional histories at both sites could not be characterized by a linear sedimentation rate; sedimentation rates in the last 30-50 years were considerably higher than during the rest of the Holocene. C : N ratios declined and began to exhibit a microalgal source signature from around the time of European settlement, which could be explained by increased nutrient flows into the Bay caused by anthropogenic activity. Analysis of stable isotopic ratios of 12C/ 13C showed that the relative contribution of seagrass and C 3 terrestrial plants (mangroves, saltmarsh) to detritus declined around the time of rapid industrial expansion (~1950s), coinciding with an increase in the contribution of microalgal sources. We conclude that the relative contribution of microalgae to detritus has increased within Botany Bay, and that this shift is the sign of increased industrialization and concomitant eutrophication. Given the lower carbon burial efficiencies of microalgae (~0.1%) relative to seagrasses and C 3 terrestrial plants (up to 10%), such changes represent a substantial weakening of the carbon sink potential of Botany Bay - this occurrence is likely to be common to human-impacted estuaries, and has consequences for the role these systems play in helping...
Yunusa, I.A.M., Manoharan, V., Odeh, I.O.A., Shrestha, S., Skilbeck, C.G. & Eamus, D. 2011, 'Structural and hydrological alterations of soil due to addition of coal fly ash', Journal of Soils and Sediments, vol. 11, no. 3, pp. 423-431.
View/Download from: UTS OPUS or Publisher's site
Purpose: We tested the potential of using coal fly ash for improving the physical and hydrological characteristics of coarse and medium-textured agricultural soils. Materials and methods: Acidic (FWA) and alkaline (FNSW) fly ashes were used to amend a range of representative agricultural soils. In the first experiment, fly ash was applied to the top 10 cm of 1-m long intact cores of a sandy loam soil at rates of 0, 12, 36 or 108 Mg/ha and sown with canola; after harvest, bulk density (BD), aggregate stability and mean weight diameter (MWD) were measured on the soil. In the second experiment, we assessed water retention at field capacity (-300 kPa) and permanent wilting point (-1,500 kPa) for sandy and loamy soils amended with FNSW at 0.0-16% (w/w). The third experiment used rainfall simulation to assess erodibility of sandy and loamy soils mixed with FNSW at rates of 0, 5 or 20 Mg/ha. Results and discussion: In the first experiment, fly ash had no significant effect on MWD of the soil. The BD in the 0-10 cm layer (topsoil) was increased with addition of FWA, while FNSW applied at 108 Mg/ha reduced BD, relative to the control treatment. This was because FNSW had lower particle and bulk densities than FWA and the test soils. Ash addition increased macro-aggregation, significantly so in the 10-20 cm layer (subsurface layer), by reducing the percentages of micro-aggregates and silt + clay particles. Thus, macro-aggregation was positively correlated (p < 0.01) with MWD, but both were inversely correlated (p < 0.01) with micro-aggregates. In the second experiment, addition of fly ash enhanced plant water availability by increasing water retention at field capacity by threefold in the sandy soil and 1.5-fold in the loamy sand, but water retention at permanent wilting point was not affected. In Experiment 3, the addition of ash at 20 Mg/ha, but not at 5 Mg/ha, increased turbidity of runoff water from the amended soil due to the dispersal of fine particles by the impact o...
Manoharan, V., Yunusa, I.A.M., Loganathan, P., Lawrie, R., Skilbeck, C.G., Burchett, M.D., Murray, B.R. & Eamus, D. 2010, 'Assessments of Class F fly ashes for amelioration of soil acidity and their influence on growth and uptake of Mo and Se by canola', Fuel, vol. 89, no. 11, pp. 3498-3504.
View/Download from: UTS OPUS or Publisher's site
Coal fly ash can be used to ameliorate productivity constraints in agricultural soils, but their efficacy still remains highly variable. To ascertain the capacity of Class F fly ashes to modify pH of acidic soils, and their effects on the yield and uptake of molybdenum (Mo) and selenium (Se) by canola (Brassica napus L.), we applied two acidic and two alkaline Class F ashes at rates equivalent to 0, 12, 36, and 108 Mg/ha to the top layer (0-10 cm) of 100 cm long intact cores of acidic sandy clay and clay loam soils. Only the alkaline ash which had the highest calcium carbonate equivalent (2.43%) increased the pH of the top 10 cm of the sandy clay soil. However, this ash was also highly saline and when applied at ?36 Mg/ha it increased the electrical conductivity in the top soil layer. Increases in soil pH as a result of alkaline ash addition also elevated concentrations of Se in the plant shoot. The ashes with high concentrations of Mo and Se generally increased uptake of these elements in the plant shoot and/or seed. When these ashes were applied at 108 Mg/ha they increased the concentrations of these elements in the treated topsoil. &copy; 2010 Elsevier Ltd. All rights reserved.
Manoharan, V., Yunusa, I.A.M., Loganathan, P., Lawrie, R., Murray, B.R., Skilbeck, C.G. & Eamus, D. 2010, 'Boron contents and solubility in Australian fly ashes and its uptake by canola (Brassica napus L.) from the ash-amended soils', Australian Journal of Soil Research, vol. 48, no. 5, pp. 480-487.
View/Download from: UTS OPUS or Publisher's site
Phytotoxicity due to excessive boron (B) uptake by plants impedes routine agronomic utilisation of coal fly ash. We assessed 11 fly ashes (pH 3.1410.77) having total B content (Bt) of 12136mg/kg, of which 2030% was hot water soluble (Bs) in the acidic ashes (pH 5) and 510% in the alkaline ashes, for their potential to supply B to plants and their risk associated with phytotoxicity. We found the Bs/Bt to be negatively correlated (R2?0.63, N?11) with ash pH. We conducted two pot trials in which canola was grown in soils amended with fly ash. In the first trial, an alkaline fly ash (Bt 66mg/kg) was incorporated at 5 rates of up to 625Mg/ha into the top 50mm of 2 acidic soils in 0.30-m-long intact cores, and sown with canola. Boron concentration in leaves at flowering reached the phytotoxic threshold, and both plant growth and seed yield were reduced, only at 625Mg/ha. In the second trial, 4 fly ashes (pH 3.2910.77, Bt 12127mg/kg) were incorporated at 4 rates of up to 108Mg/ha into the top 0.10m of 2 acidic soils in 1.0-m-long intact cores and then sown with canola. Ashes with highest Bt, when applied at 108Mg/ha, increased B concentration in the topsoil only. Of the 2 ashes with the highest B t, only that which produced low soil pH and applied at 108Mg/ha increased B concentration in the shoot, but was still below phytotoxic threshold. The results suggest that B derived from these ashes may not cause phytotoxicity and excessive soil B accumulation if the ashes are applied at modest rates (36Mg/ha) to the topsoil layers. &copy; 2010 CSIRO.
Yunusa, I.A.M., Burchett, M.D., Manoharan, V., DeSilva, D.L., Eamus, D. & Skilbeck, C.G. 2009, 'Photosynthetic pigment concentrations, gas exchange and vegetative growth for selected monocots and dicots treated with two contrasting coal fly ashes', Journal of Environmental Quality, vol. 38, no. 4, pp. 1466-1472.
View/Download from: UTS OPUS or Publisher's site
There is uncertainty as to the rates of coal fly ash needed for optimum physiological processes and growth. In the current study we tested the hypothesis that photosynthetic pigments concentrations and CO2 assimilation (A) are more sensitive than dry weights in plants grown on media amended with coal fly ash. We applied the Terrestrial Plant Growth Test (Guideline 208) protocols of the Organization for Economic Cooperation and Development (OECD) to monocots [barley (Hordeum vulgare) and ryegrass (Secale cereale)] and dicots [canola (Brasica napus), radish (Raphanus sativus), field peas (Pisum sativum), and lucerne (Medicago sativa)] on media amended with fly ashes derived from semi-bituminous (gray ash) or lignite (red ash) coals at rates of 0, 2.5, 5.0, 10, or 20 Mg ha-1. The red ash had higher elemental concentrations and salinity than the gray ash. Fly ash addition had no significant effect on germination by any of the six species. At moderate rates (? 10 Mg ha-1) both ashes increased (p < 0.05) growth rates and concentrations of chlorophylls a and b, but reduced carotenoid concentrations. Addition of either ash increased A in radish and transpiration in barley. Growth rates and final dry weights were reduced for all of the six test species when addition rates exceeded 10 Mg ha-1 for gray ash and 5 Mg ha -1 for red ash. We concluded that plant dry weights, rather than pigment concentrations and/or instantaneous rates of photosynthesis, are more consistent for assessing subsequent growth in plants supplied with fly ash. Copyright &copy; 2009 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.
Drew, S., Flett, I., Wilson, J., Heijnis, H. & Skilbeck, C.G. 2008, 'The trophic history of Myall Lakes, New South Wales, Australia: Interpretations using ?13C and ?15N of the sedimentary record', Hydrobiologia, vol. 608, no. 1, pp. 35-47.
View/Download from: UTS OPUS or Publisher's site
In an attempt to determine the trophic history of the Myall Lakes complex (New South Wales, Australia) ?13Corg, ?15N and Corg:N profiles were determined for bulk organic matter of two short sediment cores from Bombah Broadwater and Myall Lake. 210Pb profiles and sediment types indicate significantly different trophic trajectories during the time periods examined. ?13Corg and Corg:N indicate Bombah Broadwater has been dominated by increasing inputs of terrestrial organic material over the last century, thought to be related to watershed disturbance including agricultural activity. Primary production appears to be dominated by phytoplankton. ?15N remained relatively stable at around 1&#8240; until the mid-1970s when there was a sharp increase to 4.7&#8240;, interpreted as an influx of sewage-derived material. These observations offer an insight into the recent trophic changes at the site. Sedimentation rates are noticeably lower in Myall Lake and the most recent sediment is a flocculent organic rich deposit overlying mineral clay. ?13Corg and Corg:N values indicate a transition from plankton to macrophyte dominated primary production around 1800AD. ?15N values become increasingly negative from approximately 1900AD. This is interpreted as being due to increasing reliance by macrophytes on nitrogen recycled from decomposing sediments driven by natural infilling and eutrophication in this basin. The contrasting sedimentation rates, sediment types and geochemical profiles suggest the different basins of this water body are subject to substantially different internal and external influences which should be considered in management decisions. &copy; 2008 Springer Science+Business Media B.V.
Bishop, M.J., Kelaher, B.P., Alquezar, R., York, P.H., Ralph, P.J. & Skilbeck, C.G. 2007, 'Trophic cul-de-sac, Pyrazus ebeninus, limits trophic transfer through an estuarine detritus-based food web', Oikos, vol. 116, no. 3, pp. 427-438.
View/Download from: UTS OPUS or Publisher's site
The importance to food-webs of trophic cul-de-sacs, species that channel energy flow away from higher trophic levels, is seldom considered outside of the pelagic systems in which they were first identified. On intertidal mudflats, inputs of detritus from saltmarshes, macroalgae or microphytobenthos are generally regarded as a major structuring force underpinning food-webs and there has been no consideration of trophic cul-de-sacs to date. A fully orthogonal three-factor experiment manipulating the density of the abundant gastropod, Pyrazus ebeninus, detritus and macrobenthic predators on a Sydney mudflat revealed large deleterious effects of the gastropod, irrespective of detrital loading or the presence of predators. Two months after experimental manipulation, the standing-stock of microphytobenthos in plots with high (44 per m2) densities of P. ebeninus was 20% less than in plots with low (4 per m2) densities. Increasing densities of P. ebeninus from low to high halved the abundance of macroinvertebrates and the average number of species. In contrast, the addition of detritus had differing effects on microphytobenthos (positively affected) and macroinvertebrates (negatively affected). Over the two-months of our experiment, no predatory mortality of P. ebeninus was observed and high densities of P. ebeninus decreased impacts of predators on macroinvertebrate abundances. Given that the dynamics of southeast Australian mudflats are driven more by disturbance than seasonality in predators and their interactions with prey, it is likely that Pyrazus would be similarly resistant to predation and have negative effects on benthic assemblages at other times of the year, outside of our study period. Thus, in reducing microphytobenthos and the abundance and species richness of macrofauna, high abundances of the detritivore P. ebeninus may severely limit the flow of energy up the food chain to commercially-important species. This study therefore suggests that trophic cul-de...
Yunusa, I.A.M., Eamus, D., DeSilva, D.L., Murray, B.R., Burchett, M.D., Skilbeck, G.C. & Heidrich, C. 2006, 'Fly-ash: An exploitable resource for management of Australian agricultural soils', Fuel, vol. 85, no. 16 SPEC. ISS., pp. 2337-2344.
View/Download from: UTS OPUS or Publisher's site
Agricultural soils in Australia have inherent limitations of structural and nutritional nature that pose major constraints to crop productivity. These soils are still productive due to intensive management that involves routine treatments with lime and gypsum at significant costs both to the farmer and the environment. Production costs associated with these inputs average about 30% of the total cost of soil treatment. Furthermore, reserves of gypsum are under pressure. There is therefore an opportunity for the more than 13 million tonnes of coal combustion products (CCPs) produced annually by coal-fired power stations to be utilised in the management of agricultural soils. At present, about 70% of the ash is emplaced within landfills. In this paper we briefly describe the main constraints of major agricultural soils that could be ameliorated with fly-ash. We used a model to estimate that application of fine (<20 ?m) fly-ash to the top 0.15 m coarse textured (sandy) soil would reduce hydraulic conductivity by 25% and so improve water-holding capacity. The same treatment of fine textured clayey soil with coarse (>20 ?m) fly-ash would increase conductivity by up to 20%. We cite examples of studies that have shown beneficial use of coal-ash for crop production, including our ongoing glasshouse study in which fly-ash was found to increase early growth vigour and seed yield by 20% for canola (Brassica napus). There are several issues, including costs and regulation, and knowledge-gaps that need to be addressed before adoption of CCP for routine soil management. &copy; 2006 Elsevier Ltd. All rights reserved.
Skilbeck, G. & Fink, D. 2006, 'Radiocarbon dating and sedimentation rates for holocene-upper pleistocene sediments, eastern equatorial pacific and Peru continental margin', Proceedings of the Ocean Drilling Program, Scientific results, vol. 201, pp. 1-15.
View/Download from: UTS OPUS
Skilbeck, C.G. & Fink, D. 2006, 'Data report: Radiocarbon dating and sedimentation rates for Holocene-upper Pleistocene sediments, eastern equatorial Pacific and Peru continental margin', Proceedings of the Ocean Drilling Program: Scientific Results, vol. 201.
Meister, P., Prokopenko, M.G., Skilbeck, C.G., Watson, M. & McKenzie, J.A. 2006, 'Data report: Compilation of total organic and inorganic carbon data from Peru margin and eastern equatorial Pacific drill sites (ODP Legs 112, 138, and 201)', Proceedings of the Ocean Drilling Program: Scientific Results, vol. 201.
Skilbeck, C.G., Rolph, T.C., Hill, N., Woods, J. & Wilkens, R.H. 2005, 'Holocene millennial/centennial-scale multiproxy cyclicity in temperate eastern Australian estuary sediments', Journal of Quaternary Science, vol. 20, no. 4, pp. 327-347.
View/Download from: UTS OPUS or Publisher's site
We have undertaken a comparative study of down-core variation in multiproxy palaeoclimate data (magnetic susceptibility, calcium carbonate content and total organic carbon) from two coastal water bodies (Myall and Tuggerah Lakes) in temperate eastern Australia to identify local, regional and global-forcing factors within Holocene estuarine sediments. The two lakes lie within the same temperate climate zone adjacent to the Tasman Sea, but are not part of the same catchment and drain different geological provinces. One is essentially a freshwater coastal lake whereas the other is a brackish back-barrier lagoon. Despite these differences, data from two sites in each of the two lakes have allowed us to investigate and compare cyclicity in otherwise uniform, single facies sediments within the frequency range of 200-2000 years, limited by the sedimentation rate within the lakes and our sample requirements. We have auto- and cross-correlated strong periodicities at ?360 years, ?500-530 years, ?270-290 years, 420-450 years and ?210 years, and subordinate periods of ?650 years, 1200-1400 years and ?1800 years. Our thesis is that climate is the only regionally available mechanism available to control common millennial and centennial scale cyclicity in these sediments, given the geographical and other differences. However, regional climate may not be the dominant effect at any single time and either location. Within the range of frequency spectral peaks we have identified, several fall within known long-term periodical fluctuations of sun spot activity; however, feedback loops associated with short-term orbital variation, such as Dansgaard-Oeschger cycles, and the relationship between these and palaeo-ENSO variation, are also possible contributors. Copyright &copy; 2005 John Wiley & Sons, Ltd.
Meister, P., Prokopenko, M., Skilbeck, G. & Watson, M.B. 2005, 'Compilation of total organic and inorganic carbon data from Peru margin and eastern equatorial Pacific drill sites', Proceedings of the Ocean Drilling Program, vol. 201, pp. 1-20.
View/Download from: UTS OPUS
Organic matter deposited and buried under the seafloor is one of the major carbon sources for microbial life in the deep subsurfaces of the ocean. In this report we present a compilation of all available total organic carbon (TOC) and total inorganic carbon (TIC) data for the sites drilled during Ocean Drilling Program (ODP) Leg 201. We include the ODP Legs 112 and 138 (Yeats, Hart et al., 1977; Suess, Von Huene, et. al., 1988; Mayer, Pisias, Janecek, et. al. 1992), which were reoccupied during ODP Leg 201. Additional data fromLeg 201 shore-based analyses are also included int he compilation.
Marsaglia, K.M., Fukusawa, H., Cornell, W.C., Skilbeck, C.G., Meyers, P.A., Prasad, M. & Klaus, A. 2004, 'Eustatic signals in deep-marine sedimentary sequences recovered at ODP Site 978, Alboran Basin, western Mediterranean Sea', Journal of Sedimentary Research, vol. 74, no. 3, pp. 378-390.
View/Download from: UTS OPUS or Publisher's site
A continuous section of Pliocene marine sediments was recovered at Ocean Drilling Program Site 978, located in the Alboran Sea between Spain and Morocco. Three Pliocene subunits have been defined at Site 978: the lowermost (Subunit IC, 129.2 m thick) is characterized by alternating beds of lighter, more calcareous, and darker less calcareous, claystone with bioturbated upper and lower contacts (Type 1 cycles); the middle (Subunit 1B, 67.1 m thick) is composed of relatively homogeneous nannofossil claystone; and the uppermost (Subunit IA, 211.6 m thick) contains abrupt-based darker, terrigenous layers interpreted as turbidites that are interstratified with lighter nannofossil claystone (Type 2 cycles). The rhythmically bedded light and dark layers in Subunit IC correlate with those in the Rosello Composite Section of Sicily, a global reference standard for the Pliocene time scale. These sedimentary cycles are products of variations in precession and resulting continental runoff. Missing cycles occur during eustatic highstands. The shift to more homogeneous sedimentation in Subunit IB is represented in similar-aged sequences throughout the Mediterranean which display evidence of submarine mass wasting. Mediterranean-wide slope degradation was likely a response to rapid sea-level change at approximately 3 Ma. This change in sedimentation style was accompanied by an upsection increase in sediment accumulation rates associated with turbidite influx in Subunit IA. Turbidite frequency throughout the Pliocene section can be linked to eustatic changes in sea level, with turbidite maxima corresponding with mid-sequence downlap surfaces and their associated condensed sections. &copy; 2004, SEPM (Society for Sedimentary Geology).
D'Hondt, S., Jørgensen, B.B., Miller, D.J., Batzke, A., Blake, R., Cragg, B.A., Cypionka, H., Dickens, G.R., Ferdelman, T., Hinrichs, K.U., Holm, N.G., Mitterer, R., Spivack, A., Wang, G., Bekins, B., Engelen, B., Ford, K., Gettemy, G., Rutherford, S.D., Sass, H., Skilbeck, C.G., Aiello, I.W., Guèrin, G., House, C.H., Inagaki, F., Meister, P., Naehr, T., Niitsuma, S., Parkes, R.J., Schippers, A., Smith, D.C., Teske, A., Wiegel, J., Padilla, C.N. & Acosta, J.L.S. 2004, 'Distributions of microbial activities in deep subseafloor sediments', Science, vol. 306, no. 5705, pp. 2216-2221.
View/Download from: UTS OPUS or Publisher's site
Diverse microbial communities and numerous energy-yielding activities occur in deeply buried sediments of the eastern Pacific Ocean. Distributions of metabolic activities often deviate from the standard model. Rates of activities, cell concentrations, and populations of cultured bacteria vary consistently from one subseafloor environment to another. Net rates of major activities principally rely on electron acceptors and electron donors from the photosynthetic surface world. At open-ocean sites, nitrate and oxygen are supplied to the deepest sedimentary communities through the underlying basaltic aquifer. In turn, these sedimentary communities may supply dissolved electron donors and nutrients to the underlying crustal biosphere.
Ford, K.H., Naehr, T.H. & Skilbeck, G. 2003, 'The use of infrared thermal imaging to identify gas hydrate in sediment cores', Proceedings of the Ocean Drilling Program, Scientific results, vol. 201, pp. 1-20.
View/Download from: UTS OPUS
Lee, G.S.H., Mar, G.L., Rose, H.R., Marshall, C.P., Young, B.R., Skilbeck, C.G. & Wilson, M.A. 1998, 'X-ray photoelectron spectroscopy of conodonts', Organic Geochemistry, vol. 28, no. 11, pp. 759-765.
View/Download from: Publisher's site
X-ray photoelectron spectroscopy is shown to be a useful technique for the analysis of the elemental and organic composition of microfossils such as conodonts. Changes in elemental and organic composition with depth from the conodont surface can be determined in order to establish origin and thermal maturity. In this work the organic matter in conodonts with a colour thermal maturity alteration index of 4 is shown to be the product of oxidative gather than reducing environments. The C/N ratio is 20 which is close to that obtained for soils (10-12) rather than coals, kerogens or thermally matured geo-organic matter (50). Preliminary pyrolysis gas chromatography mass spectrometry, and micro-infrared and Raman spectroscopy also supports the conclusion that the organic matter differs from that predicted by the colour thermal maturity alteration index. | X-ray photoelectron spectroscopy is shown to be a useful technique for the analysis of the elemental and organic composition of microfossils such as conodonts. Changes in elemental and organic composition with depth from the conodont surface can be determined in order to establish origin and thermal maturity. In this work the organic matter in conodonts with a colour thermal maturity alteration index of 4 is shown to be the product of oxidative rather than reducing environments. The C/N ratio is 20 which is close to that obtained for soils (10-12) rather than coals, kerogens or thermally matured geo-organic matter (50). Preliminary pyrolysis gas chromatography mass spectrometry, and micro-infrared and Raman spectroscopy also supports the conclusion that the organic matter differs from that predicted by the colour thermal maturity alteration index.
Mcdonald, S.J. & Skilbeck, C.G. 1996, 'Authigenic fluid inclusions in lithic sandstone: A case study from the Permo-Triassic Gunnedah Basin, New South Wales', Australian Journal of Earth Sciences, vol. 43, no. 2, pp. 217-228.
The Gunnedah Basin is a structural subdivision of the Permo-Triassic Sydney-Bowen Basin, a major Permian coal province in eastern Australia. Coarse-grained sediments of the Permian Maules Creek, Porcupine and Watermark Formations within the basin are predominantly volcanolithic to quartz-lithic conglomerate and sandstone that were deposited in alluvial, marine fan delta and marine shelf environments. Triassic strata of the Digby and Napperby Formations were deposited in alluvial and lacustrine environments respectively. Fluid inclusions in authigenic quartz overgrowths and healed grain fractures identified in sandstone from these rocks comprise four distinct types (Types 1-4) generated during three discrete diagenetic episodes (GI [oldest]-GIII [youngest]). Two of the inclusion types (Types 3 and 4) are hydrocarbon-bearing and their distribution indicates that migration of hydrocarbons occurred late in the diagenetic history of the rocks, although homogenisation temperatures imply that emplacement of these inclusions pre-dated maximum burial temperature. Microthermometric analysis of 57 aqueous inclusions gave homogenisation temperatures ranging from 62&deg;C to 140&deg;C. The majority of samples are now located at depths shallower than those at which the fluids were entrapped and data are used to constrain the palaeothermal and tectonic history of the basin. Freezing runs yielded first melts at between -65&deg;C and -31&deg;C suggesting the presence of a Ca-Na-Cl system. Ice melts ranged from -8.5&deg;C to -0.2&deg;C and are interpreted to represent much lower salinities than would have been present in the original marine depositional environment of the Porcupine and Watermark Formations.
Platt, J.P., Soto, J.I., Comas, M.C., Zahn, R., Klaus, A., Aubourg, C., Bernasconi, S., Belanger, P., Cornell, W., De Kaenel, E., De Larouzière, F., Doose, H., Fukusawa, H., Hobart, M., Iaccarino, S., Ippach, P., Marsaglia, K., Meyers, P., Murat, A., O'Sullivan, G., Prassad, M., Siesser, W., Skilbeck, C.G., Tandon, K., Torii, M., Tribble, J. & Wilkens, R. 1996, 'Decompression and high-temperature-low-pressure metamorphism in the exhumed floor of an extensional basin, Alboran Sea, western Mediterranean', Geology, vol. 24, no. 5, pp. 447-450.
View/Download from: 2.3.CO;2">Publisher's site
Leg 161 of the Ocean Drilling Program (ODP) has made a major contribution to our understanding of the origin of the Alboran Basin by demonstrating that it is underlain by rocks of continental origin that have undergone high-temperature metamorphism and melting at exceptionally low pressure after exhumation and decompression. Basement rocks recovered from Site 976 consist of high-grade schist and gneiss derived from aluminous sediments, and minor amounts of marble, granitic dikes, and migmatitic segregations of granitic material. Mineral assemblages and textural relations show that an early assemblage including biotite, garnet, staurolite, plagioclase, and rutile is overprinted by a second assemblage of biotite, sillimanite, plagioclase, potassium feldspar, and ilmenite. Both assemblages are overprinted by andalusite, potassium feldspar, and minor garnet. Migmatitic gneiss contains relict andalusite, overprinted by sillimanite and cordierite co-existing with granitic leucosome. Preliminary pressure-temperature estimates suggest that the metamorphic evolution followed an approximately isothermal decompression path from 7 to 3 kbar at temperatures in the range 580 to 630&deg;C. After decompression, granitic melts formed at <3 kbar and >670&deg;C, after andalusite breakdown and within the sillimanite stability field. The cored rocks closely resemble high-grade metamorphic rocks in the adjacent Betic Cordillera of southern Spain, which yield early Miocene radiometric dates. At ODP Site 976 they are overlain by middle Miocene marine sediments. The combination of exhumation in an extensional tectonic environment and the evidence for high and increasing temperature during exhumation provide support for and new constraints on current models for the basin that involve the removal of lithospheric mantle below a zone of continental collision, accompanied or followed by extension.
Skilbeck, C.G. & Cawood, P.A. 1994, 'Provenance history of a Carboniferous Gondwana margin forearc basin, New England Fold Belt, eastern Australia: modal and geochemical constraints', Sedimentary Geology, vol. 93, no. 1-2, pp. 107-133.
View/Download from: Publisher's site
The Visean-?Stephanian Myall Trough, eastern Australia, formed part of a forearc basin to the east of a magmatic arc situated along the palaeo-Pacific margin of Gondwana. Petrographic, modal, whole-rock geochemistry and mineral phase chemistry of sandstones, siltstones, conglomerates and associated igneous rocks provide a consistent and coherent data set which indicate sediment derivation from a magmatic arc of predominantly silicic volcanic composition. The low-quartz modes of the sandstones, the largely volcanic origin of lithic fragments and the overall high SiO2 content of the siliciclastic sediments and igneous rocks require the arc source to be largely dacitic to rhyolitic in composition. The predominance of vitric type-? (highly siliceous volcanic rocks) lithic fragments suggests a source composed largely of silicic pyroclastics. The presence of potassium feldspar, as well as the presence of biotite as the principal detrital ferromagnesian phase in the sandstones, suggest a source of medium- to high-K tholeiite composition. The high trace element abundances of relatively immobile elements such as Zr, La, Ce, V, Nb, Y and Th and corresponding high Th/U, Zr/Y, La/Y La/Sm ratios and low Zr/Th, Zr/Nb, La/Th and Ti/Zr ratios for both the igneous rocks and derived siliciclastic sediments in the Myall Trough also require a high-K and/or strongly medium-K arc source. A lack of temporal or spatial trends in the data indicate that the magmatic arc remained of uniform composition throughout the 25 Ma interval of strata preserved within the trough. The provenance history of the Myall Trough requires accumulation along an Andean-type continental margin, rather than an intra-oceanic arc outboard of the Gondwana margin. &copy; 1994.
Philip, G.M., Skilbeck, C.G. & Watson, D.F. 1987, 'Algebraic dispersion fields on ternary diagrams', Mathematical Geology, vol. 19, no. 3, pp. 171-181.
View/Download from: Publisher's site
Previously published dispersion fields on ternary diagrams have been constructed variously, and their derivations have not been well-specified. Here an explanation of their bases is provided through an algebraic method for calculating two related forms, designated the silhouette dispersion field and the girth dispersion field. Such dispersion estimates can be made more precise by specifying the percentage of samples that fall within the field. Because such fields represent a mechanistic rather than a probabilistic approach, their use in comparison of sample sets must be viewed with caution. &copy; 1987 International Association for Mathematical Geology.


Ralph, P.J., Skilbeck, G. & Sinutok, S. AccessUTS Pty Limited 2013, Vallisneria and submerged macrophyte management in the Penrith Lakes Scheme, Sydney.
Yunusa, I.A., Veeragathipillai, M., Burchett, M., Eamus, D. & Skilbeck, G. Not applicable 2008, Utilisation of Coal Ash in Horticultural and Agricultural Ecosystems, pp. 1-111, Sydney, Australia.