Sedimentary facies

Arenas C, Pardo G (1999) Latest Oligocene-Late Miocene lacustrine systems of the north-central part of the Ebro Basin (Spain) sedimentary facies model and palaeogeographic synthesis. Palaeogeogr Palaeoclimatol Palaeoecol 151 127-148... 

Perez A, Luzon A, Roc AC, Soria AR, Mayayo MJ, Sanchez JA (2002) Sedimentary facies distribution and genesis of a recent carbonate-rich saline lake Gallocanta Lake, Iberian Chain, NE Spain. Sediment Geol 148 185-202... 

Preferred fluid migration pathways are influenced by porosity and permeability, sedimentary sequences, facies architecture, and fractures. Porosity is a measure of pore space per unit volume of rock or sediment and can be divided into two types absolute porosity and effective porosity. Absolute porosity (n) is the total void space per unit volume and is defined as the percentage of the bulk volume that is not solid material. The equation for basic porosity is listed below ... 

Reading, H. G., 1978, Sedimentary Environments and Facies Blackwell Scientific Publications, Oxford, England, 557 pp. 

Feldspars are the most abundant minerals of igneous rocks, where their ubiquity and abundance of their components influence normative classifications. They are also abundant in gneisses, and may be observed in several facies of thermal and regional metamorphic regimes. Notwithstanding their alterability, they are ubiquitously present in sedimentary rocks, as authigenic and/or detritic phases. Only in carbonaceous sediments is their presence subordinate. 

The youngest eruptive event is of Paleocene age ( 60 Ma) whereas the youngest preserved host rocks capping the Buffalo Head Hills are of Campanian age ( 78 Ma). In this instance, the only record of now eroded latest Campanian through Paleocene host rocks is provided by sedimentary xenoliths preserved in the truncated intra-crater facies ultramafic bodies (e.g., K1 body). 

In each of the different parageneses outlined here, the instability of a mineral can be denoted by its replacement with one or usually several minerals. The rocks in these facies are typified by multi-phase assemblages which can be placed in the K-Na-Al-Si system. This is typical of systems where the major chemical components are inert and where their masses determine the phases formed. The assumptions made in the analysis up to this point have been that all phases are stable under the variation of intensive variables of the system. This means that at constant P-T the minerals are stable over the range of pH s encountered in the various environments. This is probably true for most sedimentary basins, deep-sea deposits and buried sedimentary sequences. The assemblage albite-potassium feldspar-mixed layered-illite montmorillonite and albite-mixed layered illite montmorillonite-kaolinite represent the end of zeolite facies as found in carbonates and sedimentary rocks (Bates and Strahl,... 

No significant differences have been established between heulandite and laumontite in sedimentary formations in the zones of deep epigenesis (initial metamorphism), on the one hand, and the same minerals in hydro-thermal deposits, on the other. Apparently, this will require more factual data. Nevertheless, the distribution of these zeolites and the associations of clay minerals permit a distinction between the zeolite facies of regional epigenesis-metamorphism and the zeolite mineralization in geothermal areas (recent hydrothermal systems). 

The above discussion suggests that true sedimentary formations are generally poor in types of zeolites (containing only one or two species) although the origin of the zeolites is clearly controlled by the facies conditions. An indispensible condition is the presence of fresh aluminosilicate... 

Figure 2.7 Sedimentary facies in three general zones of the Ogeechee River/Ossabaw Sound estuary (USA). Fine-grained sediments predominate in the lower-energy region (stations 2, 3, and 4) as opposed to the high-energy point bars (station 5) and mouth (1) which have a higher abundance of coarse-grained sediments. (Modified from Howard et al., 1975.)...

Facies an accumulation of deposits that exhibits specific characteristics and grades laterally into other sedimentary accumulations that were formed at the same time but exhibit different characteristics. 

Elliott, T. (1978) Clastic shorelines. In Sedimentary Environments and Facies (Reading, H.G, ed.), pp. 143-175, Elsevier, New York. 

The cherty iron (sedimentary) formation (CIS) is the most uniform in facies. The cherty iron beds are traced for 10-20 km their thickness reaches 100-300 m and their iron content reaches 30-35%. According to Semenenko... 

Garrels et al. (1973) believe that the BIF must have been formed in restricted basins in semi-enclosed water bodies, periodically communicating with the ocean via channels or over bars. Deposition of silica occurred mainly during evaporation, but deposition of iron was complex and is explained both by oxidation (hematite facies) and by evaporation (silicate and carbonate facies) and sulfate reduction (sulfide facies). It is suggested that the spatial distribution of the sedimentary facies of the BIF will correspond to the well-known scheme of James (1954), but to explain the similarity of banding in the face of different causes of precipitation of the iron raises difficulties. 

The formation of other primary iron mineral compounds is determined by the presence in solution of active forms of silica, carbon, and sulfur. The sediments can be subdivided provisionally into four groups oxide, silicate, carbonate, and sulfide, formally corresponding to the sedimentary facies of the iron-formation, according to James (1954). For each group of sediments the relationships between iron compounds were determined by calculation, in a wide range of pH (from 0 to 14) and Eh (from -I-1.0 to —1.0 V). 

James considered all the typical parageneses of the BIF to be primary sedimentary and distinguished oxide, silicate, carbonate, and sulfide facies, deposited at different depths of the basin, where different oxidation-reduction conditions existed. 

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