Sedimentary sequences

The shape and structure of the carbonates and surrounding rock types suggest the carbonates are an intrusive structure rather than representing a sedimentary sequence. 

The geology of Cyprus is dominated by four distinct terranes - the Troodos Ophiolite Complex composed of mafic and ultramafic rocks, the Circum-Troodos Sedimentary Sequence containing calcarenites, siltstones and carbonates, the Mamonia Complex composed of igneous, sedimentary and metamorphic rocks and the Kyrenia Terrain containing a series of allochthonous massive and recrystallised limestones dolomites and marbles. These terranes generate highly varied landscapes (Fig 1). 

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 ... 

Metalliferous sediments are a common component of modern ocean-floor sedimentary sequences, recording halos of metal dispersion from seafloor hydro-thermal vent systems (Gurvich, 2006). Sulfidic black shales are also commonly present as intercalations in ancient subaqueous volcanic sequences, where each likely represents a significant hiatus in volcanic activity and deposition. These shale horizons form geophysical anomalies (conductors) that are routinely drilled during exploration for volcanogenic massive sulfide (VMS) base metal deposits. 

All rocks of the area belong to the sedimentary sequence of the Selwyn basin of late Proterozoic to Mississippian age (Abbott et al. 1986), and are on a... 

VMS deposits of the BMC occur within a Middle-Ordovician bimodal volcanic and sedimentary sequence in the northern Appalachians of New Brunswick, Canada (Goodfellow McCutcheon 2003). Volcanic rocks were emplaced between 472 and 455 Ma within an intra-continental back-arc basin (the Tetagouche-Exploits basin) at the eastern margin of the proto-Atlantic (lapetus) Ocean (van Staal et al. 2003). 

Paleozoic sedimentary sequence (limestones, quarzites, and pelites), and a Quaternary cover complete the stratigraphic column. 

The northern part of the Bendigo-Baiiarat zone consists of an Ordovician fiysch sequence which has been complexly deformed and intruded by late Devonian granitoids. In the south-western part of the study area Tertiary basalt overlies much of the Ordovician sedimentary sequence. Practically all known goldfields and mineralized zones have been discovered in areas where Ordovician sedimentary rocks crop out. 

Adams, S.S. Smith, R.B. 1988. Geology and recognition criteria for sandstone uranium deposits in mixed fluvial-shallow marine sedimentary sequences, South Texas. Bendix Field Engineering Corporation, Grand Junction, Colorado NURE Report GJBX-4(81), 146 p. 

The data of Schlenker (1971) indicates that corrensite is not specifically related to the occurrence of gypsum in evaporites although this mineral is present in the sedimentary sequence where corrensite is found. We can assume then that corrensite occurrence is a factor both of chemistry and physical conditions acting upon a sediment or rock. 

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,... 

Figure kk. Temperature-depth plot for the sedimentary sequences in which a major change in the organic matter occurs. V, LA = Ventura and Los Angeles basins, Philippi (1965) BP = Paris basin L = Logbaba core ... 

Buonasorte G, Fiordelisi A, Pandeli E, Rossi U, Sollevanti F (1987) Stratigraphic correlations and structural setting of the pre-neoautochthonous sedimentary sequences of Northen Latium. Per Mineral 56 111-122... 

Sample description and preparation. The samples analysed in this study are listed in Table I together with available geochemical data. Table II provides general burial history information for the four sedimentary sequences. 

Table II. Burial history information for the four sedimentary sequences studied...

Figure 4. Variation in the thiophene ratio (TR) with depth for samples from four sedimentary sequences. For samples from the Paris Basin, maximum depths of burial from Mackenzie et al (23) were used.

The relationship between Rock-Eval Tmax and depth for the different sedimentary sequences is depicted in Figure 8. For a given sequence... 

Figure 6. Ternary plots showing the variation in relative abundances of 2,3-dimethylthiophene, n-non-l-ene and 1,2-dimethylbenzene with depth (meters) for samples from the four sedimentary sequences. Maximum depths of burial are given for samples from the Paris Basin.

Figure 8. Relationship between Rock-Eval pyrolysis T and depth for samples from the four sedimentary sequences (modified after Eglinton et al., 5). Continued on next page.

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