Key Features:

Methodology

OCTek uses a new gravity inversion technique (see references above) 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 are 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 a 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.

Input Data and Output Results

OCTek works 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 and beta factor
- residual thermal gravity anomaly

OCTek Reports

OCTek Phase 1 investigated the conjugate margins of the South, Equatorial and Central Atlantic. OCTek Phase 2 investigated the basins and margins of the Asia-Pacific region. OCTek Phase 3 will investigate the rifted margins of the Indian Ocean. OCTek Phase 4 will investigate the basins and margins of the North Atlantic and Arctic.

Availability

OCTek-Atlantic and OCTek-Asia/Pacific are available now. OCTek-Indian Ocean is underway and should be available in Mid-2011. OCTek-Arctic/Atlantic should be available at the end of 2011.

Key Benefits:

Deliverables

The primary output from OCTek is a suite of digital grids which are available for unrestricted use to purchasing companies and institutions. The grids are supported by an atlas of maps, which documents 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 helps to discriminate likely crustal thickness and crustal type across the ocean-continent transition prior to any specific data acquisition.

Improved estimates for thinning

For Petroleum Systems Modelling, maps are produced of beta/thinning factor and residual continental crustal basement thickness across rifted margins and their ocean-continent transitions.

Proven Methodology

OCTek is using input data already in the public domain, but the techniques of OCTek are also available on a confidential client 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