Generic identity and diagenesis of Pennsylvanian phylloid algae revealed by cathodoluminescence

Conference · Tue May 01 00:00:00 EDT 1990 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:6699268

Moshier, S O ^[1]; Kirkland, B ^[2]

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1. Univ. of Kentucky, Lexington (USA)
2. Louisiana State Univ., Baton Rouge (USA)

The late Paleozoic phylloid algae are of problematic, although likely diverse, affinity. Phylloids in the Pennsylvanian Providence Limestone (Desmonesian) in western Kentucky are typical in appearance: millimeter-long leaf forms composed of a calcite mosaic lacking relict fabrics. Petrography with cathodoluminescence, however, reveals details of internal features that enable generic identification of these phylloids as the ancestral coralline Archeolithophyllum. Nonluminescent cellular material and luminescent pore-fill calcite delineate clearly defined Polygonal hypothallial and perithallial tissue. Backscattered electron imaging is also helpful in distinguishing skeletal and diagenetic material in the algae. Hypothallial pores are 25 {times} 50 {mu} and commonly are arranged in arcuate layers (referred to as coaxial tissues). Cellular walls are thin (5 {mu}) and contain scattered holes or pits (1 {mu} diameter), some filled with pyrite. Low magnesium and high strontium contents of the skeletal material suggest an aragonitic precursor mineralogy (Mg average, 519; range 0-2,016 ppm; Sr average, 4,461; range, 388-10,549 ppm). These phylloids do indeed share morphological, structural, and compositional characteristics with Holocene Squamariacean genera composed of aragonite. Generations of calcite-filling cellular pores change from bright yellow to dull red luminescence. Electron microprobe data indicate continuous enrichment in the magnesium, manganese, and iron content of the diagenetic fluids. Iron content of the last pore-fill calcite ranges to 22,875 ppm but averages 12,296 ppm. Strontium is progressively depleted in these cements.

• OSTI ID: 6699268
• Report Number(s): CONF-900605-; CODEN: AABUD
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 74:5; Conference: Annual convention and exposition of the American Association of Petroleum Geologists, San Francisco, CA (USA), 3-6 Jun 1990; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CARBONATE ROCKS
DIAGENESIS
KENTUCKY
ALGAE
CALCITE
CARBONIFEROUS PERIOD
FOSSILS
GEOCHEMISTRY
IRON
MAGNESIUM
MANGANESE
PETROGRAPHY
STRONTIUM
TRACE AMOUNTS
ALKALINE EARTH METAL COMPOUNDS
ALKALINE EARTH METALS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CHEMISTRY
ELEMENTS
FEDERAL REGION IV
GEOLOGIC AGES
METALS
MINERALS
NORTH AMERICA
OXYGEN COMPOUNDS
PALEOZOIC ERA
PLANTS
ROCKS
SEDIMENTARY ROCKS
TRANSITION ELEMENTS
USA
580000* - Geosciences