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Professor Greg Skilbeck

Biography

Greg 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.

He has been on the academic staff of the University of Technology, Sydney, since 1988 and is currently Professor of Earth Sciences. Over the past 20 years his research interests have ranged from sedimentation associated with convergent margins, specifically in reconstructing basin forming-processes from stratigraphic sequences. In order to provide modern constraints on these studies, he participated in the 1995 Mediterranean tectonics leg of the Ocean Drilling Program (Leg 161) and consequently developed an interest in marine geology and palaeoclimatology.

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).

Professional

Employment History:
2007- : 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).

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
Executive Director, Research Strategy and Int Research, Faculty of Science
Professor, School of the Environment
Core Member, Centre for Environmental Sustainability
BSc (Hons) (Syd), PhD (Syd)
 
Phone
+61 2 9514 1760
Room
CB07.07.24

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:

  • 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)

Past Teaching:
  • 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.

Journal articles

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.
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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., Loganathan, P., Nissanka, S.P., Manoharan, V., Burchett, M.D., Skilbeck, C.G. & Eamus, D. 2012, 'Application of coal fly ash in agriculture: A strategic perspective', Critical Reviews in Environmental Science and Technology, vol. 42, no. 6, pp. 559-600.
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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.
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.
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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.
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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. 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.
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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. 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.
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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 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.
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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 until the mid-1970s when there was a sharp increase to 4.7, 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. 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.
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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...
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.
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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 2005 John Wiley & Sons, Ltd.
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.
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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. 2004, SEPM (Society for Sedimentary Geology).
D'Hondt, S., Jrgensen, 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., Gurin, 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.
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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.