1887
Volume 42, Issue 2
  • ISSN: 0812-3985
  • E-ISSN: 1834-7533

Abstract

Abstract

A marine continuous seismic profiling (CSP) study and a resistivity study of vibrocore samples of shallow marine sands were undertaken in Jervis Bay, NSW, Australia, to characterise the seabed. The CSP study also included Crookhaven Bight, adjacent to Jervis Bay facing north-east to the ocean. The overall aims were: (i) to estimate sediment thickness, and surficial sediment resistivity (upper 3 m) at selected sites, to explore the features of the bedrock topography; and (ii) combined with upper layer (sea water) parameters that can be accurately measured, to provide a simplified geo-electrical model of the ground (sea water/seabed) to support interpretation of airborne electromagnetic survey data. The results of the CSP studies indicate very dense sands (tighter packing) and variably weathered sandstones, suggesting variable geological conditions below the seabed. The bedrock surface was also highly irregular in places suggesting an erosional pulse(s) under rapidly falling sea levels at various times in the past. Bedrock was found to form the sea floor in some locations and is deeply incised by palaeochannels extending to 62 m below sea level in the Crookhaven Bight and Jervis Bay entrance areas.

The laboratory resistivity values, obtained from four electrode measurements on seawater saturated subsamples, averaged 0.88 Ωm (20°C). Inter- and intra-site changes in mineralogy (shell/sand), grain packing, grain size, grain shape, cohesion, and inferred porosity were thought to be responsible for minor variations in resistivity. Archie Equation plots showed some scatter, but the data indicate a cementation factor of ~1.6 and an average formation factor of 4.3 for the suites of sands. These values are consistent with values cited in the literature.

© 2011 ASEG
Loading

Article metrics loading...

/content/journals/10.1071/EG10037
2011-06-01
2026-01-13

  • From This Site

    /content/journals/10.1071/EG10037
    dcterms_title,dcterms_subject,pub_keyword
    -contentType:Journal -contentType:Contributor -contentType:Concept -contentType:Institution
    10
    5
Loading full text...

Full text loading...

References

  1. Albani, A. D., Carter, A. N., and Johnson, B. D., 1973, The bedrock topography of Jervis Bay, New South Wales: Oceanography of the South Pacific 1972, comp. R. Fraser, New Zealand Commission for UNESCO, Wellington, 1973, 179–184.
     [Google Scholar]
  2. Archie G. E. 1942 The electrical resistivity log as an aid in determining some resevoir characteristics: Transactions AIME 146 54 62
    [Google Scholar]
  3. Bennet, R. H., Lambert, D. N., Hulbert, M. H., Burns, J. T., Sawyer, W. B., and Freeland, G. L., 1983, Electrical resistivity/conductivity in seabed sediments, in R.A Geyer, ed., CRC Handbook of Geophysical Exploration at Sea: CRC Press Inc., 333–375.
     [Google Scholar]
  4. Biella G. Lozej A. Tabacco I. 1983 Experimental study of some hydrogeophysical properties of unconsolidated sediments: Ground Water 21 741 751 10.1111/j.1745‑6584.1983.tb01945.x
    https://doi.org/10.1111/j.1745-6584.1983.tb01945.x [Google Scholar]
  5. Emerson D. W. 2000 Magnetic susceptibility in sedimentary basin studies – some features of the Hawkesbury Sandstone: Preview 87 135 138
    [Google Scholar]
  6. Glover P. 2009 What is the cementation exponent? A new interpretation: The Leading Edge 28 82 85 10.1190/1.3064150
    https://doi.org/10.1190/1.3064150 [Google Scholar]
  7. Jackson P. D. Taylor Smith D. Stanford P. N. 1978 Resistivity-porosity-particle shape relationships for marine sands: Geophysics 43 1250 1268 10.1190/1.1440891
    https://doi.org/10.1190/1.1440891 [Google Scholar]
  8. Kermabon A. Gehin C. Blavier P. 1969 A deep-sea electrical resistivity probe for measuring porosity and density of unconsolidated sediments: Geophysics 34 554 571 10.1190/1.1440031
    https://doi.org/10.1190/1.1440031 [Google Scholar]
  9. Taylor G. 1972 Sedimentation in Jervis Bay: Proceedings of the Linnean Society of New South Wales 96 Part 4 297 306
    [Google Scholar]
  10. Taylor, G., , Abell, R., and Paterson, I., 1995, Jervis Bay – a place of culture, scientific and educational value, in G. Cho, A. Georges, and R. Stoutjesdijk, eds., ANPWS, 41–52.
     [Google Scholar]
  11. Vrbancich J. 2009 An investigation of seawater and sediment depth using a prototype airborne electromagnetic instrumentation system – a case study in Broken Bay, Australia: Geophysical Prospecting 57 633 651 10.1111/j.1365‑2478.2008.00762.x
    https://doi.org/10.1111/j.1365-2478.2008.00762.x [Google Scholar]
  12. Vrbancich J. Fullagar P. K. 2007 Towards remote sensing of sediment thickness and depth to bedrock in shallow seawater using airborne TEM: Exploration Geophysics 38 77 88 10.1071/EG07006
    https://doi.org/10.1071/EG07006 [Google Scholar]
  13. Vrbancich, J., Whiteley, R. J., Caffi, P., and Emerson, D. W., 2011, Marine seismic profiling and shallow marine sand resistivity investigations in Broken Bay, NSW, Australia: submitted for publication in Exploration Geophysics.
     [Google Scholar]
  14. Whiteley R. J. Stewart S. B. 2008 Case studies of shallow marine investigations in Australia with advanced underwater seismic refraction (USR): Exploration Geophysics 39 34 40 10.1071/EG08009
    https://doi.org/10.1071/EG08009 [Google Scholar]
/content/journals/10.1071/EG10037
Loading
Marine seismic profiling and shallow marine sand resistivity investigations in Jervis Bay, NSW, AustraliaFN1
Exploration Geophysics 42, 127 (2011); https://doi.org/10.1071/EG10037
/content/journals/10.1071/EG10037
/content/journals/10.1071/EG10037
Loading

Data & Media loading...

  • Article Type: Research Article
Keyword(s): bedrock topography, Jervis Bay, marine seismic, sediment resistivity, sediment thickness.

Most Cited This Month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error