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Recent biogenic phosphorite: concretions in mollusk kidneys
Science (New York, N.Y.)
|March 31, 1978
Summary
Researchers discovered phosphorite concretions in mollusk kidneys, revealing direct biogenic formation of these grains. This finding offers new insights into marine phosphorite deposit origins beyond chemical precipitation.
Area of Science:
- Marine Biology
- Geochemistry
- Biomineralization
Background:
- Phosphorite deposits are significant marine geological formations.
- Their origin is often attributed to chemical precipitation, but some deposits remain unexplained.
- Mollusks are common marine organisms with high population densities.
Purpose of the Study:
- To investigate the direct biogenic formation of phosphorite grains.
- To identify the composition and structure of concretions found in mollusks.
- To explore the potential role of mollusks in marine phosphorite formation.
Main Methods:
- Detection of phosphorite concretions in the kidneys of Mercenaria mercenaria and Argopecten irradians.
- Chemical analysis of concretion composition.
- X-ray diffraction analysis to determine crystalline structure upon heating.
Main Results:
- Phosphorite concretions were found in the kidneys of two mollusk species.
- The concretions are primarily amorphous calcium phosphate, transforming to chlorapatite upon heating.
- This represents the first documentation of direct biogenic phosphorite grain formation.
Conclusions:
- Biogenic formation of phosphorite concretions is a normal excretory process in mollusks under stress.
- Over time, diagenetic changes and secondary enrichment of biogenic phosphorite may contribute to marine phosphorite deposits.
- This biological pathway offers an alternative explanation for certain marine phosphorite deposits.
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