Dear Dr. El Nady,

The organic facies stands for the accumulation of organic matter (OM), which may be subdivided into a coal facies developing as paralic and lacustrine/alluvial-fluvial ones (see among others the textbook of Diessel) and a hydrocarbon facies (see among others the books of Vine and Tourtelot). It contrasts with the lithofacies which is, in places,  intertonguing with this facies realm (see among others books of Miall, Flügel and Warren for siliciclastic, calcareous and evaporitic environments). You can write a textbook in this Q&A process conducted here on what subfacies exist. The disciplines and techniques most successfully applied to decipher or analyze these facies types are organic (plus inorganic) chemistry and coal petrography (see Teichmüller et al.). The papers are numerous and mainly published in the Journal of coal geology, Fuels, Chemical geology..

Best regards

H.G.Dill

okay thanks sir

The concept of "Organic Facies" was introduced during the increase of the integration between microscopy and organic geochemistry methods. The primary objective of organic facies studies is the prediction of the likely occurrence (and lateral variability) of hydrocarbon source potential as a function of depositional environment (Mendonça Filho et al, 2011; 2012). Depending on the objectives of the study and the parameters used for its definition, geoscientists observe the lateral variations of a certain organic facies both at the “basin scale” and at “slide scale”. Based on a paleoecological and paleoclimatic vision, an organic facies can identify both small and large cycles related to transgressive-regressive events. However, its characterization is also related with the depositional paleoenvironments and with the deposition of the stratigraphic units responsible for the generation of oil. In this manner, the application of this concept is wide and several authors consider the introduction of this term in the literature considering it is an indispensable exploration tool (Tyson, 1995).  According Peters and Cassa (1996), many authors use the term organic facies as a synonym of kerogen facies, based on chemical data, or palynofacies or facies of the maceral association, based on petrographic data. The term organic facies was first used by Rogers (1980). Organic facies were defined by “the organic matter content (primarily type, less frequently amount), its source and depositional environment”. Cornford et al. (1980) summarized the group of organic parameters (organic petrography and geochemistry parameters) that characterize an association of sediments as “Organofacies”.  According to Peters et al. (1981), a sedimentary organic facies is determined in the type of the precursor organism, in the depositional paleoenvironments, and in the initial conditions of diagenesis of the organic matter. Habib (1982) considered organic facies a particular aspect of the organic faciology (which can be determined by the palynological study of organic matter), and it can be considered as “palynologically defined organic facies”. A formal definition was proposed by Jones and Damaison (1980, 1982), where an “organic facies is a detectable subdivision of a certain stratigraphic unit which can be discriminated by the characteristics of the organic constituents without considering the aspects of the inorganic fraction of the sediments”. Powell (1987) presents the same concepts in his definition of organic facies, considering the effect of the depositional control on the composition of organic matter of potentially hydrocarbon source rocks. This effect regards to the nature of the primary biomass (algal, bacterial, or from land plants/higher plants), to the extent of bacterial degradation (reworking) during deposition and to the lithology of the source rock, and to the chemical composition of the waters present in the depositional paleoenvironment (salinity, pH, alkalinity and oxygenation). Tuweni and Tyson (1994) consider that TOC and pyrolysis data combined with palynofacies analysis provides an excellent means of characterizing organic facies. According to Tyson (1995), the concept of organic facies can be defined as a “group of sediments aving a distinctive set of organic constituents that can be recognized by microscopy or be associated to a characteristic organogeochemical composition”. Jones (1987) in a classical study developed the organic facies concept. This author defined seven organic facies using geochemical, and to a lesser extent optical data. These organic facies have been assigned to either individual samples, groups of samples or whole stratigraphic units and parameters used correspond to immature sedimentary intervals with vitrinite’s reflective power, approximately 0.5%VR. This organic facies approach is probably more realistic than kerogen type in attempting to classify different kerogen assemblages as it takes into account the fact that the assemblages are controlled by preservational factors as well as their source, and that changes between assemblages are often gradational (Tyson, 1995).

Cornford C., Rüllkötter J., Welte D., 1980. A synthesis of organic petrographic and geochemical results from DSDP sites in the eastern central North Atlantic. Phys. Chem. Earth, 12, 445-453.

Habib D., 1982. Sedimentary supply origin of cretaceous black shales. In: Schlanger S.O., Cita M.B. (Eds.), Nature and origin of Cretaceous Carbon-rich Facies. Academic Press, London, pp. 113-27.

Jones, R. W., Demaison, G. J., 1982. Organic Facies - stratigraphic concepts and exploration tool. In: Saldivar-Sali, A. (Ed.). Proceedings of the Second ASCOPE Conference and Exhibition, Manilla, Asean Council on Petroleum, pp. 51-68.

Jones, R. W., 1987. Organic Facies. In: Brooks, J., Welte D. (Eds.), Advances in Petroleum Geochemistry 2. Academic Press, London, pp. 1-90.

Mendonça Filho, J. G. ; Menezes, T. R. ; Mendonca, J. O. 2011. Organic Facies. In: Flores, D.; Marques, M. (Org.). ICCP Training Course on Dispersed Organic Matter. Porto: Plenimagem, 2011, v. , p. 99-106.

Mendonça Filho, J.G.; Menezes, T.R.; Mendonca, J.O.; Oliveira, A.D.; Silva, T.F.; Rondon, N.F.; Silva, F.S. 2012. Organic Facies: Palynofacies and Organic Geochemistry Approches. In: Dionisios Panagiotaras. (Org.). Geochemistry Earth and System Processes. 1ed. Patras: InTech, 2012, v. 1, p. 211-245.

Peters, K.E., Cassa M.R., 1994. Applied source rock geochemistry. In: Magoon L.B. and Dow W.G. (Eds.), The Petroleum System – from Source to Trap. AAPG Memoir, 60, 93-120.

Powell, A. J., 1987. Thanetian dinoflagellate cyst biostratigraphy and quantitative palynostratigraphy of the Andrew Field, Central North Sea. In: British Micropalaeontological Society Meeting Micropalaeontology, Palynology, and Petroleum Exploration, on - and offshore Europe, University of Aberdeen.

Rogers, M. A., 1980. Application of organic facies concepts to hydrocarbon source rocks evaluation. In: Proceedings of the 10th World Petroleum Congress, Bucharest 1979, Heyden, London, 2, 23-30.

Tuweni A.O. and Tyson R.V. (1994) Organic facies variations in the Westbury Formation (Rhaetic, Bristol Channel, SW England). Organic Geochemistry, 21:1001-1014.

Tyson, R.V., 1995. Sedimentary Organic Matter. Organic facies and palynofacies. Chapman and Hall, Londres, 615 pp.

Thank you very much Proof. João Graciano Mendonça Filho

Dear Dr. El Nady

Microscopic investigations support organic based facies which is comprised all types of fossil remains (e.g. Algea, foraminifers, etc). Organo-detrital sediments are clear type which show the organic remains in sedimentary facies (rudist of Upper Cretaceous of Oman and Iran) (Afghah and Yaghmour, 2014; Afghah and Farhoudi, 2012 and Afghah, 2010) . Similar the mentioned strata, detectable rudist remains of Cenomanian sequence in Iraq and Iran (Afghah et al., 2014; Al -Dilaimi et al., 2013; Schumann, 1995 ).     

 It should necessary to examine sedimentary rocks by geochemistry  methods.

As you know conversion organic constituent topetroleum formation reflects organic matter in source rocks.   

thanks dear sir