An example of mixing-zone dolomite, Middle Eocene Avon Park Formation, Floridan aquifer system

Journal Article · Fri Jul 01 04:00:00 EDT 1994 · Journal of Sedimentary Research - Section A; (United States)

OSTI ID:7034355

Cander, H S ^[1]

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1. AMOCO Production Co., Houston, TX (United States)

A late-formed dolomite cement in a core of the Middle Eocene Avon Park Formation, peninsular Florida, provides an example of dolomite cement from a mixing zone and illustrates how dolomite textural alteration and stabilization can occur at earth-surface conditions. The Avon Park Formation is a pervasively dolomitized peritidal platform carbonate 400 m thick in the Florida aquifer system. Typical Avon Park dolomite is inclusion-rich, fine-grained (< 40 mm), noncathodoluminescent, highly porous (average, 20%), and formed during the Eocene by normal to hypersaline seawater ([delta][sup 18]O = + 3.7[per thousand] PDB; [delta][sup 13]C = + 2.0[per thousand]; [sup 87]Sr/[sup 86]Sr = 0.70778; Sr = 167 ppm). In a 20 m interval in a core from southwest Florida, inclusion-free, cathodoluminescent dolomite overgrows the early-formed noncathodoluminescent marine dolomite. The cathodoluminescent dolomite cement profoundly alters the texture of Avon Park dolomite from typical Cenozoic-like porous, poorly crystalline dolomite to hard, dense, low-porosity, highly crystalline Paleozoic-like dolomite. The dolomite cement is not a replacement of limestone but an overgrowth of early-formed marine dolomite and pore-occluding cement. This study demonstrates that: (1) dolomite precipitated from a 75% seawater mixing-zone fluid that was both calcite saturated and sulfate-rich, and (2) dramatic textural maturation and stabilization in dolomite can occur in the near surface environment, without elevated temperature and burial conditions.

• OSTI ID: 7034355
• Journal Information: Journal of Sedimentary Research - Section A; (United States), Journal Name: Journal of Sedimentary Research - Section A; (United States) Vol. 64:3; ISSN XZ288H
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540250 -- Environment
Terrestrial-- Site Resource &amp; Use Studies-- (1990-)
58 GEOSCIENCES
580000* -- Geosciences
AQUIFERS
CARBONATE MINERALS
CATHODOLUMINESCENCE
CHEMICAL COMPOSITION
CHEMISTRY
DEVELOPED COUNTRIES
DOLOMITE
FLORIDA
GEOCHEMISTRY
GEOLOGIC FORMATIONS
LUMINESCENCE
MINERALOGY
MINERALS
NORTH AMERICA
PRECIPITATION
SEPARATION PROCESSES
USA