Voyage Plans and Summaries

[back to voyage document index]

Franklin Voyage Plan No. FR08/00

Title

The Continent-Ocean Transition of the Crust and Mantle across the North West Shelf (Leg 2)

Itinerary

Depart Dampier 1000 hrs, Friday 22 September 2000
Arrive Dampier 1000 hrs, Monday 25 September 2000

Principal Investigator(s)

Dr Graham Heinson (Chief Scientist)
Adelaide University
Department of Geology and Geophysics
Adelaide SA 5005
Tel 08-8303-5377
Fax 08-8303-4347
gheinson@geology.adelaide.edu.au

A/Prof. Antony White (Project Leader)
Flinders University
School of Earth Sciences
GPO Box 2100, Adelaide SA 5001
Tel 08-8201-2212
Fax 08-82011-2676
awhite@es.flinders.edu.au

Scientific Objectives

The north west margin of Australia includes the Pilbara Archaean shield, the Phanerozoic Canning and Canarvon sedimentary basins and the Exmouth Plateau. Geophysical measurements of magnetic and electric fields onshore and offshore provide a means of imaging the crust and mantle structure in terms of electrical conductivity. The principal aims of the project are:

(a) to determine crust-mantle structure and anisotropy across the continental margin, from Archaean shield to ocean abyssal plain;

(b) to investigate the Canning Basin conductivity anomaly across the margin and its relationship to extensional faults imaged from deep-seismic profiles of the Fitzroy Trough.

Cruise Objectives

Up to twelve seafloor MT instrument (squares in Figure 1) will be recovered from the seafloor deployments sites established from the first leg of the cruise in August. The same instrumentation was recently recovered off the coast of Eyre Peninsula (1998) and Gulf of Carpentaria (1999) in a similar configuration, so we foresee no logistical difficulties.

Figure 1 : Geology, instrument locations and ship tracks for the first cruise. The main geological units are the Archaean Shields of the Pilbara and Kimberley Blocks, between which lies the Canning Basin. The Canning Basin electrical conductivity anomaly is shown by the dashed line marked CBA. Circles show approximately the proposed instrument locations on land. At sea, squares show location of the long-period instruments that will be deployed for a few weeks, while triangles show the sites of short-period instruments that are deployed for two-days at a time.

Cruise Track and Time Estimates

The cruise will simply leave Dampier and steam along the line of instruments (squares in Figure 1), starting from the deepest site and ending up at the coast. Up to twelve instruments will be recovered during the cruise.

Day 1. Leave Dampier, steam to outer site in 5000 m of water. Estimated distance 400 nm @ 10 knots = 40 hours.

Recover twelve instruments (approximately 40 hours and 12 instruments @ 1.5 hours each = 58 hours)

Day 4. Return to Dampier. Total time required = 98 hours = 4 days

Piggy-back Project

Two berths on this cruise will be made available to researchers from the Cetacean Ecosystem Program at Deakin University, who will participate as cetacean observers.

Franklin Equipment

Franklin’s bottom mounted 12 kHz transducer as on previous cruises.

User Equipment

Eight seafloor magnetotelluric instruments, four seafloor magnetometer instruments, acoustic deck unit.

Personnel List

Dr G. Heinson, Adelaide University, Chief Scientist, Recover OBEMs
A/Prof A. White, Flinders University, Project Leader, Recover OBEMs
Dr F.E.M. Lilley, ANU, Magnetomer Recovery
Prof. K. Bahr, Goettingen University, Marine Geophysics
Dr F. Simpson, Goettingen University, Marine Geophysics
*TBA, Deakin University, Cetacean Observer
*TBA, Deakin University, Cetacean Observer
Ron Plaschke, CMR, Cruise Manager
Lindsay Pender, CMR, Computing
Erik Madsen, CMR, Electronics

* The cetacean observers will also participate on the transit leg from Darwin leaving on Sunday, 17 Sep 2000 and sailing to Dampier arriving Thursday, 21 September 2000.

This cruise plan is in accordance with the directions of the National Facility Steering Committee for the Research Vessel Franklin.

John Wallace
Ships Manager

Updated: 31/01/03