Bibliographic Citation
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| Title | Sandstone diagenesis above and below a pressure seal - Tuscaloosa Trend, Louisiana |
| Creator/Author | Weedman, S.D. ; Albrecht, W. ; Brantley, S.L. (Pennsylvania State Univ., University Park (United States)) |
| Publication Date | 1991 Mar 01 |
| OSTI Identifier | OSTI ID: 7079116 |
| Report Number(s) | CONF-910403-- |
| Other Number(s) | Journal ID: ISSN 0149-1423; CODEN: AABUD |
| Resource Type | Conference |
| Specific Type | Journal Article |
| Resource Relation | Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States); Journal Volume: 75:3; Conference: Annual meeting of the American Association of Petroleum Geologists (AAPG), Dallas, TX (United States), 7-10 Apr 1991 |
| Subject | 02 PETROLEUM; 03 NATURAL GAS; LOUISIANA; NATURAL GAS DEPOSITS; PETROLEUM DEPOSITS; RESERVOIR ROCK; DIAGENESIS; CALCITE; CEMENTS; CHLORITE MINERALS; DISSOLUTION; DOLOMITE; GEOLOGIC FORMATIONS; MICROSTRUCTURE; MINERALOGY; POROSITY; SANDSTONES; BUILDING MATERIALS; CARBONATE MINERALS; CRYSTAL STRUCTURE; DEVELOPED COUNTRIES; FEDERAL REGION VI; GEOLOGIC DEPOSITS; MATERIALS; MINERAL RESOURCES; MINERALS; NORTH AMERICA; RESOURCES; ROCKS; SEDIMENTARY ROCKS; SILICATE MINERALS; USA |
| Description/Abstract | Significant diagenetic differences are observed in the Lower Tuscaloosa sandstone sampled above and below a pressure seal. Additionally, textural evidence suggests that the high porosity (> 20%) in some of the sandstones is secondary. Samples are classified into two groups: normal' (< 12%) and high porosity (12-24%). The normal' porosity sandstones, situated predominantly above the seal, are cemented by either quartz or calcite. At some grain-quartz overgrowth contacts, dissolution of overgrowths and portions of grains is concurrent with precipitation of calcite; some calcite is partially replaced by saddle dolomite. Pore-lining chlorite is present but rare in the normal' porosity sandstones. The high porosity sandstones, situated predominantly below the seal, retain remnants of quartz and carbonate cements; virtually all pores are lined with chlorite. High porosity is attributed primarily to dissolution of carbonate cement. Evidence for previously existing carbonate cement includes: remnant cement, rhomb-shaped porosity, and partially dissolved quartz grains whose surfaces are similar to grain surfaces of the calcite-cemented sandstones. The characteristic robust pore-lining chlorite growth is attributed to accelerated dissolution of volcanic rock fragments with the increase in porosity and permeability after carbonate dissolution. The authors suggest that the pressure seal plays two roles in creating and preserving high porosity: (1) the seal impedes fluid flow between two zones of different fluid chemistry and therefore different paragenesis in rocks of essentially the same age and depositional environment, and (2) the seal creates a compartment in which fluid pressures support the rock, inhibiting further compaction after the dissolution of the cement. |
| Country of Publication | United States |
| Language | English |
| Format | Medium: X; Size: Pages: 690 |
| System Entry Date | 2008 Feb 12 |
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Last Updated: 11/19/2009