I found quite huge idiomorphic apatite crystals (up to 0,5 mm) in the Anisian shallow water limestones and they look pretty much like porphyroblasts with pressure shadows. Limestones are highly recrystallized with mylonitic texture.
Whether an increase in temperature can cause the growth of apatites from phosphorus rich limestones?
What is the origin of phosphorus?
Francolite synonymous with carbonate fluorapatite or
called collophane when microcrystalline
is the principal component of many sedimentary
phosphate rocks (“phosphorite”). Brushite (41.24 wt.% P2O5 ) and
monetite (52.16 wt.% P2O5) are only widespread in guano deposits,
where locally rather exotic phosphate minerals accommodating N, O
and H bridge the gap between organo-mineralic chemical compounds
and inorganic chemical compounds (coastal region in Chile). They can be the source of your apatite when recrystallized.
Marine upwelling along the shelf edge is responsible for the formation of carbonate-hosted phosphates and phosphorites. Some phosphorites accumulated within high energy — nearshore zones. Some formed in the outer shelf deposits. The common minerals besides francolite are smectite, illite, opal, sepiolite, clinoptilolite, quartz , siderite, smectite and palygorskite.
When they undergo physical-chemical alteration, e.g., an increase in T apatite may recrystallize and form XX of different X shape from elongated to stubby XX (pisms). You should investigate your apatite s.s.s. and determine how much carbon dioxide, F , Cl and OH is still in the XX. The OH- and CO3- anion complex should decrease along with increasing T. Also have a look at the minerals associated with the phosphate. The minerals mentioned above only occur in diagenetically overprinted phosphate-bearing limestones.
There are many phosphate deposits hosted by calcareous rocks.
See: DILL, H.G. and KANTOR, W. (1997) Depositional environment, chemical facies and a tentative classification of some selected phosphate accumulations.- Geologisches Jahrbuch, D 105: 3-43.
HGD
The origin of P is the seawater. That is why our skeletons contain P (our ancestors formed in the sea).
Hi Matija Vukovski
Here is one very relevant study to your question, I just saw.
https://www.sciencedirect.com/science/article/abs/pii/S0895981116302073
Chapter A Comparative Study of the Diagenesis in Diapir-Influenced R...
Best Regards,
SHA
- Badges
- Science method
- Similar topics
- Biological Science
- Ecology