| Autor: |
Leho Ainsaar, Toivo Kallaste, Tarmo Kiipli, Enli Kiipli |
| Jazyk: |
angličtina |
| Rok vydání: |
2010 |
| Předmět: |
|
| Zdroj: |
Estonian Journal of Earth Sciences, Vol 59, Iss 4, Pp 247-255 (2010) |
| Druh dokumentu: |
article |
| ISSN: |
1736-4728 |
| DOI: |
10.3176/earth.2010.4.01 |
| Popis: |
Baltoscandian Middle and Upper Ordovician carbonate rocks are relatively poor in phosphorus, with the P2O5 content of 0.05–0.5%, rarely exceeding 1%. Phosphorus distribution in the Ordovician carbonate succession shows spatial and temporal variations. In the Estonian Shelf P content is the highest in the Middle Ordovician, close to the Tremadocian P-rich siliciclastic sediments, decreasing towards younger carbonate rocks. In the basinal, i.e. deep shelf, sections two intervals of elevated P contents occur: the first is similar to the shallow shelf in the lowermost Darriwilian, the second is a moderate P increase in the upper Darriwilian–Sandbian interval. The Darriwilian–Sandbian interval of elevated P content in the deep shelf sections roughly corresponds to algal kukersite accumulations in the shallow shelf. Multiple processes determined phosphorus distribution in the studied sediments. Regional processes influencing P distribution include seawater circulation, e.g. P influx by coastal upwellings, and sedimentation rate. Global oceanic variation in bioproduction (δ13C trends) had no positive effect on P accumulation in the Baltoscandian epeiric sea. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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