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On Nov 23, 2016, at 3:50 PM, timothy debacker <[log in to unmask]> wrote:TimcheersAlso - not sure about scale here - but do you have any detailed grav data over that area?Hi Craig,My initial thought was salt and structures related to salt mobilisation too, with top images showing section through lateral parts. However, if so, where did the salt originate from? Is the red reflector in the bottom image truly showing top basement? Some clues may be found in lithology and stratigraphy, and tectonic evolution of the area. Without these, also Janos's comment seems possible.On Wed, Nov 23, 2016 at 11:03 PM, Katie Gates <[log in to unmask]> wrote:Hi Craig-
The peak or high amplitude as you call it indicates the mystery horizon has a faster velocity than the surrounding sediment. My initial interpretation was also salt but I work exclusively on seismic data in the Gulf of Mexico and may be biased!
Best of luck!
Katie Gates
Geophysicist
Schlumberger
Houston, TexasHi Craig,Interesting seismic. An interpretation is a challenge, especially because I have no idea of the stratigraphy and the geological setting, but I shall give it a go:What strikes me about the section in the bottom left corner is, that the beds in the center of the image have dropped down a lot.This can be the case in a pull-apart situation in s strike-slip zone, or if the deeper formation is very mobile such as for example salt.Also the top of the deep formation is very irregular. It reminds me of a section in a salt tectonics environment.If that is correct, then the apparently isolated bodies in the middle of the other two pictures can be explained as salt structures. They look strange in insolation, but a section across a side of a salt “mushroom” can give you the isolated geometry as seen into first picture. The second picture could be part of a salt mushroom, but now intersected closer to the central part of the mushroom.I would like to see deeper seismic, and I wonder if on deeper sections it would be possible to see velocity effects of the salt on a yet deeper formation. All of course assuming that the salt hypothesis is correct.On the section at the top left, it seems that a section on the right hand side of the picture is “sagging”, this could be associated with salt withdrawal, which is supported by the congruent sagging of the deep (salt) formation. To the left of the down moving zone the beds seem to move up, which could be the result of salt flowing from the sagging area to the left were there is now more uprising of salt. Extreme uprising results in the formation of a diaper, such as I interpret on the bottom left image.I would love to hear your final assessment.Regards, DirkDr Dirk Nieuwland
4e Binnenvestgracht 13
2311NT LeidenOn 23 Nov 2016, at 17:59, Magee, Craig <[log in to unmask]> wrote:Dear all,A slight plea for help here. For those who like a mystery…does anyone have any ideas what on Earth these features are??? These are time-migrated, seismic reflection images – the seabed is just about visible at the top and the sediment-basement interface is the high-amplitude reflection at the bottom. The top two images are of the same feature (two orthogonal sections) and the bottom left is a different structure at a slightly high stratigraphic level.<image001.jpg>We have been puzzling over these for a while and are keen to hear what ideas fresh sets of eyes may have! To avoid bias, that is all I’ll say. If you would like more information, better images, or a copy of a small cropped volume (the data is freely available) please do let us know.We look forward to hearing your ideas!Kind regards,Craig Magee, Jenny Reeves, and Chris JacksonDr Craig MageeResearch Fellow,Room 2.60Basins Research Group (BRG),Department of Earth Science & Engineering, Imperial College, LONDON,SW7 2BPUKPersonal Website: http://www3.imperial.ac.uk/people/c.magee Research Group Website: http://www.basinsresearchgroup.com/ Phone: +44 (0)20 7594 6510Twitter: @DrCraigMagee