There are many field photographs needing some explanations about meso and small scale structures.
It is very much looking like "plumose structures" at the surface of a joint. You have at least two families of joint here (one more or less parallel to the plane of the picture and another one perpendicular).
Dear Melody, thanks a lot for your participation........, but the picture has combination structures......and has more than one phase of deformation .....
I agree with Melody, I see joints here. I'm guessing that the rock is a siliceous tuff. There is a vague hint of stratification at the top of the photo tracing roughly horizontally across the top of the photo. Evidence for multiple phases of deformation is not jumping out at me from this photo.
Dear David, the rock is chalky limestone and no siliceous nor tuff in this unit, in addition to the previously mentioned by me I see stylolites and granulation....
It is surprising that chalk limestone has so sharp edges as it seem from the photo. I was also considering it as a kind of siliceous (or silicified) rock. I do not agree with David completely that multiple (brittle) deformation cannot be seen from the photo. Two or three generations of joints can be seen. The oldest and irregular one seen at the upper part of the photo runs subhorizontally could be bedding as well. The shape of fractures connected to this joint (bedding surface) suggest dextral displacement that I would consider as a first phase of deformation (D1). It is crosscut by the second generation joints (D2) running vertically (as Melody said) and having local slickensides (surface near the compass string). The third generation crosscuts all other structures (D3), is perpendicular to the second generation and runs parallel to the photo surface (as Melody said). There also, some slickensides can be noticed on the left edge of the photo. The third generation surfaces seem corroded, but I cannot see stylolites (at least they do not seem to me as stylolites from the photo).The rock is obviously very finegrained and compact having plumose structure on splited surfaces.
Thanks Mirka, your explanation is the best as I see all these what you talked about.
To be more precise the lithology is micritic limestone (fine) and chalky limestone
Is this a scientific answer?...................................................
there three at least three fracture sets in this photo. F1 is slightly horizontal and irregular as ( as Mirka said ) but it is not bedding plane. F2 is parallel to the photo and F3 which is vertical and crosscut F2 .
I think some of this fractures are artificial fractures and not tectonic .
There are no artificial fractures . The question was not about the number of fracture sets, but on the type and classification of these fractures...in addition to phases of deformation if possible.
Следует делать серию фотографий методом телескопирования - от детализации узлов до фотопанорамы всего обнажения. Тогда будет понятна структура и ее элементы.
In which language this answer, can you repeat the answer in English.....please
A language is Russian. Use an electronic translator.
It is necessary to do the series of photo the method of telescoped. From working out in detail to photopanoram of all of outcrop. Then a structure, its elements and genesis, will be clear.
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