I have taken these field outcrop photos from deep marine deposits in Malaysia, mostly considered as Turbidite. How to describe these typical layering. Circular? Weathered surface show highly fractured behaviour.
Always found this type of sandstone in the sandy part, overlying or after the black shales and/or underlying or before interbed sand silt heterolithic sediments!
I would also appreciate if someone can suggest any paper or book for sedimentary features of turbidites and associated deep marine rocks especially related to subduction of accretionary prism. Regards
Dear Mr. Ahme:
Any interpretation directed towards solving a geodynamic issue should be avoided based upon the present photographs of the outcrops. The images display oxidizing zones which strictly follow the curved bedding structures in the sandstones. It is a redox process which is controlled by the presence of Fe-bearing minerals be a phyllosilicate- or a heavy mineral group mineral. The Fe is dissolved , oxidized and re-concentrated in form of limonite crusts. It is a process which took place at shallow depth under near-ambient conditions. Going beyond this line would by a matter of conjecture for me.
With kind regards H.G.Dill
Dear Mr. Ahme,
I don't sure whether you has do some work about mineral composition. If haven't, I speculate it is a kind of recrystallize Fe-bearing travertine.
Best wish,
Zhao
Looks like liesegang layering. I'd agree with H.G. Dill on these few photos.
Ciao
John
Dear Nisar,
from your pictures I see 2 things:
1- convolute bedding in sandstone layer
2 - greyish and reddish colours associated to redox phenomena, well explain by Pr Harald G. Dill
Convolute bedding are commonly associated to Bouma sequence in turbidite, however Convolute bedding can also be formed by post sedimentation processes induce by earth quakes (seismites).
To be sure of Turbidite, you need to find the complete Bouma sequence
https://en.wikipedia.org/wiki/Bouma_sequence
Kind regards
Unlikely to be turbidites. I agree with prof. Dill about oxidizing zones.
it might be some convolute bedding or some soft sediment deformation, you don't need a deep marine setting or high angle slope to create such features, even in a very gentle slope of 1 degree, you might have such structures. I had a similar example in Ghadames basin and it was interpreted as a delta front turbidite, since it contain much sand content, no graded bedding observed in a very gentle slope context. I would recommend to have some articles about (Emiliano Mutti) sequence of turbidite, if you still have some doubt ( http://www.searchanddiscovery.com/pdfz/documents/2011/30214mutti/ndx_mutti.pdf.html )
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