Diagenetic zones

Figure 7.37. Idealized burial diagenetic evolution of a polymineralic assemblage of carbonate minerals as they pass through meteoric diagenetic zones. (After James and Choquette, 1984.)...

H2S (ii) isotope effects associated with cyclic oxidation- reduction reactions and (iii) the mechanism of addition of sulfur to sediments. The last two of these factors, and possibly the first as well, are depth dependent. For this reason it is logical to divide this discussion by diagenetic zone. 

O Brien, G.W. Woods, E.P. (1995) Hydrocarbon-related diagenetic zones (HPDZs) in the Vulcan Subbasin, Timor Sea recognition and exploration implications. Aust Petrol. Explor. Ass. J., 35, 220-253. 

Diagenetic zone (or more precisely, diagenetic illite crystallinity zone) after Kibler (1964, 1968), the diagenetic zone is a pre-metamorphic stage defined by illite crystallinity (IC) valu es greater than 0.42 A°20 as measured on the <2 gm fraction of clay-rich, normal clastic rocks under conditions that correspond to the recommendations on sample preparation, X-ray diffraction settings and interlaboratory standardization as summarized by Kisch (1991). 

Anchizone after Kibler (1964, 1968), a transitional zone between the diagenetic zone and the epizone as defined by IC mean values between 0.42 and 0.25 A°20. [Kaolinite and/or dioctahedral illite/smectite interstratified clay mineral with more than about 10% expandable layers are absent in normal clastic rocks, but they may persist in carbonate rocks, and in organic matter-rich, Na-rich and K-poor shales.]... 

Figure 2. Diagenetic zones of authigenic minerals in tuffs and tuffaceous sediments. The length of the zone is roughly proportional to the depth range.

Table I. Ranges of Temperature, Depth, and Total Pressure of the Upper Limit of Each Diagenetic Zone...

Sinking particles transport trace elements to the sediments. Once in the sediments, chemical reactions can resolubilize a significant fraction of the particulate metals. This process is termed diagenetic remobilization and is the subject of the next chapter. The resolubilized elements can diffuse across the sediment-water interface into the deep zone. 

Jonasson, I.R. Goodfellow, W.D. 1986. Sedimentary and diagenetic textures, and deformation structures within sulfide zone of Howards Pass (XY) Zn-Pb deposit, Yukon and Northwest Territories. In Mineral Deposits of Northern Cordillera, Special Volume 37, Canadian Institute of Mining and Metallurgy, 51-70. 

Hartgets WA, de Leeuw JW, Sinninghe Damste JS, Diagenetic and catagenetic products of isotenietatene Molecular indicators for photic zone anoxia, Geochim Cosmochim Acta 60 4467—4496, 1996. 

Sheppard and Cude report two sorts of assemblages those where zeolites are dominant, towards the lake edge and those where feldspar is dominant, towards the lake center. There are two groups of assemblages of diagenetic minerals which characterize these two zones ... 

Figure 8.16. A hypothetical trend of changes in the stable isotope composition of carbonate cements in different diagenetic environments. A- marine realm B-meteoric realm C- mixing zone D- successively deeper burial for calcite spar E-successively deeper burial for saddle dolomite. B through E are precipitated in progressively hotter waters. (After Choquette and James, 1987.)...

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