X-radiography of trace fossils in limestones and dolostones from the Jurassic Smackover Formation, south Alabama

Conference · Tue Jan 01 00:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6650695

Esposito, R A; Castleman, S P; King, Jr, D T

X-radiography has been useful in studying biogenic sedimentary structures in unconsolidated sediments but the technique has not been applied often to the study of hard carbonate rock. The authors have applied x-radiography to the study of the lower part of the Smackover to enhance the complete petrologic description of the rock. The lower Smackover has many dense micrite intervals and intervals of monotonous, thin graded beds. Parts of the lower Smackover is also dolomitized. None of the above rocks contains significant amount of skeletal debris and trace fossils are not generally obvious in an etched slab of core. In limestone, they have detected well-preserved trace fossils by x-radiography, however. The dolostones show no traces using our method. In limestones, the traces are marked by minute amounts of finely divided iron sulfides. This causes a slight density difference resulting in greater x-ray absorption. They recognize two main trace-fossil types: a Thalassinoides best seen in slabs cut parallel to bedding and a Zoophycos best seen in slabs cut perpendicular to bedding. The technique requires a slab cut 8 mm thick with parallel flat surfaces and a medical x-ray unit using accelerating voltages of 66 kV and 10 mas. Traces are most successfully imaged on industrial-quality films.

• Research Organization: Auburn Univ., AL (USA)
• OSTI ID: 6650695
• Report Number(s): CONF-8510489-
• Journal Information: Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
ALABAMA
DOLOMITE
LIMESTONE
PALEONTOLOGY
PETROLOGY
X-RAY RADIOGRAPHY
FEASIBILITY STUDIES
FOSSILS
GEOLOGIC FORMATIONS
JURASSIC PERIOD
ALKALINE EARTH METAL COMPOUNDS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATE ROCKS
CARBONATES
FEDERAL REGION IV
GEOLOGIC AGES
GEOLOGY
INDUSTRIAL RADIOGRAPHY
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MESOZOIC ERA
MINERALS
NORTH AMERICA
OXYGEN COMPOUNDS
ROCKS
SEDIMENTARY ROCKS
USA
580300* - Mineralogy
Petrology
& Rock Mechanics- (-1989)