Paragenetic sequence

Figure 1.132. Paragenetic sequence of the Hosen No. 5 vein (Takahashi et al, 1998).

Qensral feature of paragenetic sequence of gangue minerals,... 

Heinrich, C. A., and Eadington, P. J., 1986a, Thermodynamic predictions ofthe hydrothermal chemistry of arsenic and their significance for the paragenetic sequence of some cassiterite-arsenopyrite-base metal sulphide deposits Economic Geology, v. 81, p. 511-529. 

Fig. 15. Simplified paragenetic sequence of the main diagenetic processes in the Lower and Middle Lunde sandstones.

The paragenetic sequence and porosity/permeability evolution pathways of the Serraria sandstones were controlled by multiple factors that include variations in the sedimentary facies, climatic conditions and burial history. 

Characteristic burial history diagrams and paragenetic sequences of the distal and proximal domains of the basin are shown in Figs 17, 18 and 20. However, dilferent areas in the same domain were subjected to dilferent subsidence or uplift intensities. There is no available burial history curve for the middle domain, but the diagenetic evolution there is shown in Fig. 19. 

Fig. 17. Paragenetic sequence and burial history in the Caioba area of the distal domain. Dashed lines in the burial diagram represent variation in depth during telodiagenesis within the domain (from PETROBRAS, unpublished data).

Fig. 19. Paragenetic sequence of the Serraria sandstones in the middle domain.

Fig. 9. Probable paragenetic sequence of major diagenetic events in (A) the Lower Freshwater Molasse and (B) the Upper Marine Molasse.

The temporal relationships between the various diagenetic processes, inferred from their spatial arrangement and the paragenetic sequence, are shown in Fig. 7. A comparison of depositional and diagenetic characteristics of lenses and host rock is shown in Fig. 8. 

Fig. 7. Paragenetic sequence in the Luxemburg Sandstone as determined from textural relationships. Present weathering processes are omitted in this diagram.

Fig. 10. Generalized paragenetic sequence in the shelf hybrid arenites and in turbidite feldspathic litharenites.

Pore-filling cements in the central basin show a characteristic paragenetic sequence of early siderite to dolomite to calcite. In terms of abundance, calcite is by far the most abundant and siderite is the least common. Photomicrographs of cement types are shown in Fig. 4. 

These petrographic data indicate that the overall paragenetic sequence is (i) syndepositional... 

Fig. 11. Paragenetic sequence for the Upper Angel Formation, Angel Field. Dolomite cementation was a relatively late, pore-filling diagenetic event that occurred, at least in part, synchronously with microfracturing and hydrocarbon migration (see Fig. IOC). Later-stage anhydrite cement precipitated in some Angel Formation sandstones at Angel-2 and, to a lesser extent, at Angel-4.

Fig. 15. Paragenetic sequence for the Namur Sandstone, Gidgealpa Field. Calcite cementation is the major, most recent pore-filling event in the Lower Namur Sandstone, where syntaxial quartz overgrowths are minimal. In the Upper Namur Sandstone, where major calcite-cemented zones are absent, quartz cementation could have continued until relatively recent times.

Fig. 16. Schematic paragenetic sequences of diagenetic events in Hibernia Field based on petrofabric evidence. Abundance of cements and intensity of dissolution events indicated by width of the bar.

Fig. 17. Generalized paragenetic sequence for the Tirrawarra Sandstone in the Fly Lake-Moorari area. Cooper basin. The interpretation is based on the integration of petrographic, isotope and fluid inclusions results. The estimated timing of oil generation and migration is indicated (shaded zone). S1, early generation of siderite cement S2, middle generation of siderite cement S3, late generation of siderite cement D1 and D2, first and second phases of siderite dissolution, respectively.

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