Share Email Print
cover

Proceedings Paper

Phosphatized algal-bacterial assemblages in Late Cretaceous phosphorites of the Voronezh Anteclise
Author(s): Svetlana Yu. Maleonkina
Format Member Price Non-Member Price
PDF $14.40 $18.00

Paper Abstract

Late Cretaceous phosphogenesis of the Voronezh Anteclise has occurred during Cenomanian and Early Campanian. SEM studies show the presence of phosphatized algal-bacterial assemblages both in Cenomanian and Campanian phosphorites. In some Cenomanian nodular phosphorite samples revealed empty tubes 1 - 5 microns in diameter, which are most likely trichomes of cyanobacterial filaments. Other samples contained accumulations of spheres 0,5-3 microns, similar to coccoidal bacteria. Complicated tubular forms with variable diameter 2 - 5 microns occur on surface of some quartz grains in nodules. They are probably pseudomorphs after algae. We found similar formations in the Campanian phosphate grains. Frequently, grain represents a cyanobacterial mat, which is sometimes concentrically coated by phosphatic films. The films of some grains retain the primary structure, their concentric layers are formed by pseudomorphs after different bacterial types and obviously they represent oncolite. In other cases, the primary structure is unobservable because of recrystallization process erases them. Occasionally, the central part retains the coccoidal structure and the recrystallization affects only films. Besides the core of such oncolite can be represented not only by phosphatic grain, but also by grains of other minerals, such as quartz, glauconite and heavy minerals, which serve as a substrate for cyanobacterial colonies. Bacteria also could settle on cavity surfaces and interiors frames of sponge fragments, teeth and bones.

Paper Details

Date Published: 30 January 2003
PDF: 6 pages
Proc. SPIE 4939, Instruments, Methods, and Missions for Astrobiology VI, (30 January 2003); doi: 10.1117/12.486700
Show Author Affiliations
Svetlana Yu. Maleonkina, Institute of the Lithosphere of Marginal Seas (Russia)


Published in SPIE Proceedings Vol. 4939:
Instruments, Methods, and Missions for Astrobiology VI
Richard B. Hoover; Alexei Yu. Rozanov; Jere H. Lipps, Editor(s)

© SPIE. Terms of Use
Back to Top