Computer Science
Scientific paper
Apr 1986
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1986gecoa..50..551f&link_type=abstract
Geochimica et Cosmochimica Acta, vol. 50, Issue 4, pp.551-561
Computer Science
7
Scientific paper
Sandstones and shales of the lower Eocene Wilcox Group extend from outcrop to depths greater than 5 km where temperatures exceed 200°C. Eight authigenic minerals have been identified. Quartz, kaolinite, calcite, ankerite and albitized plagioclase are volumetrically significant, whereas chlorite, illite, albite overgrowths and dolomite are present only in trace amounts. Quartz, kaolinite, and ankerite cements are present over the entire depth range sampled (1528 to 4446 m). Calcite cement occurs only in sandstones shallower than 3300 m. Albitized plagioclase is the predominant feldspar in samples deeper than 2600 m whereas detrital potassium feldspar has been completely dissolved out of sandstones deeper than about 3200 m. No systematic variations in the chemical composition of calcite with depth, no zoning within calcite or ankerite, and no compositional differences between pore-filling and grain-replacing calcite or ankerite were found. Calcite cements have 87 Sr / 86 Sr ratios generally less than 0.708, whereas ankerite cements are significantly enriched in 87 Sr. The oxygen isotopic composition of carbonate cement ranges between -9 and -14%. (PDB) for calcite and between -8 and -12%. for ankerite with no systematic variation with depth. Calculated 18 O values for authigenic quartz and kaolinite range from +22 to +31%. (SMOW) and from +14 to +17%., respectively. Volumetrically important amounts of authigenic quartz and kaolinite precipitated during early burial before calcite cementation, secondary porosity generation, or smectite to illite transformation in encasing shales. The isotopic composition of strontium in calcite cement shows most of it to be of Eocene or older marine carbonate origin. Ankerite cementation followed the generation of secondary porosity and occurred after the products of organic maturation and shale diagenesis, plagioclase albitization or potassium feldspar dissolution significantly affected the sandstone-pore water system.
Fisher Stephen R.
Land Lynton S.
No associations
LandOfFree
Diagenetic history of Eocene Wilcox sandstones, South-Central Texas does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Diagenetic history of Eocene Wilcox sandstones, South-Central Texas, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Diagenetic history of Eocene Wilcox sandstones, South-Central Texas will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1102299