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Distribution of phosphorus in the Middle and Upper Ordovician Baltoscandian carbonate palaeobasin

2010; Estonian Academy Publishers; Volume: 59; Issue: 4 Linguagem: Inglês

10.3176/earth.2010.4.01

1736-7913

E Kiipli, Tarmo Kiipli, T Kallaste, Leho Ainsaar,

Astro and Planetary Science

Baltoscandian Middle and Upper Ordovician carbonate rocks are relatively poor in phosphorus, with the P 2 O 5 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 (δ 13 C trends) had no positive effect on P accumulation in the Baltoscandian epeiric sea.