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Title: Deep-burial diagenesis in carbonates. Final report, January 16, 1984-March 31, 1985

Technical Report ·
OSTI ID:5824111

The objectives were to gain an understanding of what makes or breaks porosity in carbonate rocks as a result of deep-burial, to develop criteria for deep-burial diagenesis in carbonate rocks, and to apply these criteria for interpretation of carbonate rocks now at shallow depth. Compaction tests reveal that ooid samples show substantial reductions of bulk-volume and porosity when squeezed at temperatures and pressures comparable to overburden of 3.5 to 6.5 km. Particle breakage and deformed particle contacts developed that are comparable to those reported from oolites from the rock record. Reproducibility of pressure solution by compaction supports the conclusion that initial pore-volume reduction through mechanical grain adjustments and ultimate pressure solution are major processes in the diagenetic evolution of limestone. In the deep Analdarko Basin of Oklahoma and Texas, the Hunton Group carbonate rocks of Upper Ordovician to Lower Devonian show that dolostones alone provide porosity. Studies reveal that corrected measurement of bulk densities yield improved estimates of true porosity and water saturation. The mechanism of burial dolomitization was suggested to be the underlying marine Sylvan Shale which provided necessary Mg+2 and Fe+2 during smectite-to-illite transition. Also detailed studies of core samples and thin sections from the Lower Ordovician Ellenberger carbonate rocks in the Permian Basin demonstrated that carbonate rocks below 10,000 ft are exclusively dolostone showing some evidence of deep-burial dolomitization. Lower Ordovician carbonate strata in undeformed belts of the northern Appalachian Basin yield depth of burial and paleotemperature data implying a former depth of burial which has not been usually inferred for this area. Fluid-inclusion suggests burial depth of several kilometers. 41 refs., 12 figs., 2 tabs.

Research Organization:
Rensselaer Polytechnic Inst., Troy, NY (USA). Dept. of Geology
DOE Contract Number:
AC02-81ER10921
OSTI ID:
5824111
Report Number(s):
DOE/ER/10921-T2; ON: DE85011224
Country of Publication:
United States
Language:
English