Dear Mr. Nejad,

your attempt to interpret the carbonate (micro) facies is very ambitious and is in my opinion not the correct way because the term facies is a far-reaching one to discuss the origin of a rock unit, in this case a sedimentary one where all available features of different scales need to be considered. The late Professor Walliser from Göttingen University once showed us a hand specimen and said: “ You should not create a new orogeny using only one hand specimen”.

With kind regards

H.G.Dill

In order to answer this question, you need to consider the entire succession in which this particular rock ( horizon) is found, both vertically and laterally. What type of adjacent lithologies does the rock pass into? I am not familiar with the geology of Iran, or that particular region the rock has been sampled from. Sandy limestone usually indicates an influx of terrigenous material into the sea where the carbonate has been deposited. So it might indicate a proximal (near shore environment). This is one possibility. There could be many explanations. The entire succession has to be examined both vertically and laterally. So as Dr. Gill stated do not try to interprete facies from a single sample only. That would be too ambitious.

There are many text books and papers (publications) which can help ypu.

Suggested literatures to mention but very few,

- Tucker and Wright 1990, Carbonate sedimentology.

- Flugel 1982, Microfacies of Limestones

- Flugel, 2005, Microfacies of Carbonate Rocks.

- Boggs 2004, Sedimentology and Stratigraphy

Reading 1986, Sedimentary environments and facies.

Scholle et al, 1983, carbonate depositional environments.

- Several publications of AAPG, IAS and SEPM dealing with carbonates as well as journals.

Dear Harald G. Dill and Gilamichael

Tanks for your idea that are very important. I need some references about sandy Limestons or Limy sandstons.

Some fossils seen in photos, are there Rudist or not?

Are the darker colored large clasts phosphatic? Does the sequence fine upward? This looks like the beginning of a transgression where larger clasts are mixed into finer sediments.

Dear Clements

There are not any phosphatic grains. This sequence becomes pelagic limestone upward.

if you have fossil hand specimens as well as thin section, send them or show them to a rudist specialist. It is not clear in this microphoto to identify bivalves or other fossils. If there are pelagic limestones above, then this might indicate a deepening upward sequence. Use the references I listed before.