Key Features:

Methodology

OCTek uses a new gravity inversion technique to produce maps and grids of crustal thickness and continental lithosphere thinning factor at rifted continental margins and their ocean-continent transitions (OCT). The maps and grids will be made available in both their present-day coordinate framework and also their restored coordinate framework at the time of breakup, immediately prior to ocean-basin formation.

New Gravity Inversion

Key to the new gravity inversion technique is the incorporation into the inversion scheme of:
- The lithosphere thermal gravity anomaly resulting from breakup, which at the time of breakup is very strong negative anomaly, relaxing slowly with time
- Prediction of new volcanic crustal addition during breakup, using the melt parameterization models of our former iSIMM colleague Prof Bob White (White & McKenzie 1989, Journal of Geophysical Research; Bown & White 1994, Earth and Planetary Science Letters).
Published results have shown the importance of incorporating both these parameters in the inversion when investigating deepwater margins.

Application

OCTek is initially being applied to the Atlantic between coordinates -65oS and 60oN and includes the South, Equatorial and Central Atlantic.

Input Data

OCTek will work with gravity, bathymetry and sediment thickness data to produce maps and grids of:
- depth to Moho
- total crustal thickness
- residual continental-crustal thickness
- crustal thinning factor

Availability

The product will be available in spring 2010 and will be launched at AAPG New Orleans in April 2010. OCTek will then be applied to the Asia-Pacific region with that product available in autumn 2010

Key Benefits:

Deliverables

The primary output from OCTek will be the digital grids which will be available for unrestricted use to purchasing companies and institutions. The grids will be supported by an atlas of maps, which will document the techniques and data used together with a plot from all of the supplied grids.

Improved crutsal thickness maps

In New Ventures exploration, output from OCTek will help to discriminate likely crustal thickness and crustal type prior to any specific data acquisition

Improved estimates for thinning

For Petroleum Systems Modelling, maps can be easily derived of beta/thinning factor and residual continental crustal basement across rifted margins and their ocean-continent transitions

Proven Methodology

OCTek will work with data already in the public domain, but the techniques of OCTek are also available on a confidential basis using proprietary data and have already been applied with much success to commercial studies in the following geographic areas: South America, West Africa, Gulf of Mexico, Australia, Asia-Pacific, Indian Ocean, Arctic Ocean and the southern Mediterranean.

Available Study

A study applying the OCTek gravity inversion methodology (without plate reconstruction) to the conjugate South Australia – Antarctic margins has been made available for public download by Geoscience Australia. The work was performed by Nick Kusznir on Geoscience Australia’s in-house data:
- Project Summary & Free download of report
- Download digital grids