dataset: TSHEOTWTWT

Otway Basin Top Sherbrook Two Way Time Structure Map using sun shading. Sun angle 80, azimuth 35 and vertical exaggeration 10. Pixel colours indicate red shallow (0ms), purple deep (4813ms) The top of the Sherbrook Group has also been extensively mapped in the Otway Basin, both onshore and offshore, as the event coincides with the breakup of Australia and Antarctica. This image is based on mapping done by Minerals and Petroleum Victoria, Primary Industries and Resources South Australia, and Oil Company of Australia. Several structural features are visible in this image including the Portland Trough and Bridgewater High. The Portland Trough shows up as an elongate NW-trending depression approximately 120 km long and 25 km wide centred on the peninsula SW of Portland. About two-thirds of the trough is located onshore; the other third offshore. The Bridgewater High is located offshore to the SW of the Portland Trough and shows up as a broad, Seplunging anticline about 25 km wide. The distribution of faulting at the Top Sherbrook Group level is quite interesting as most of it is located to the south of the Tartwaup - Mussel Hingeline in the Voluta Trough. In this image, the Tartwaup - Mussel Hingeline is not as well defined compared to the Top Eumeralla TWT structure map, but its arcuate trace is still visible. North of it, there is very little faulting at the Top Sherbrook level when compared to the south, where the faults have a strong NW-SE orientation and are characterised by relatively small, down-to-the-south, throws. The faulting decreases in intensity towards the SE, and virtually dies out SE of the Portland Trough and Bridgewater High. Another interesting feature which shows up on the Top Sherbrook Group grid are a series of SW-plunging folds visible offshore SW of the Otway Ranges. These folds are also visible in the Top Eumeralla and Top Wangerrip TWT structure images and extend onshore into the Colac Sub-basin and Otway Ranges. The Port Campbell Embayment is also clearly evident in this image as a semi-circular depression facing southwest. The Shipwreck rough has no expression at this level. This image is extracted from Petroleum Atlas of Victoria Figure C23 (November 2001) The entire report may be downloaded ( at no cost ) from https://gsv.vic.gov.au/searchAssistant/document.php?q=parent_id:43977