Reconstruction of currents in the Mid-Ordovician–Early Silurian central Baltic Basin using geochemical and mineralogical indicators

Study of volcanic ash beds using biostratigraphy, sanidine composition and immobile elements within bentonites has manifested several well-established and some provisional correlations between Gotland and East Baltic sections. Energy dispersive X-ray fluorescence microanalysis of phenocrysts has revealed bentonites containing Mg-rich or Fe-rich biotite. Sanidine phenocrysts contain, in addition to a major Na and K component, often a few per cent of Ca and Ba. On the basis of new correlations the mapping of the distribution areas of bentonites has been extended from the East Baltic to Gotland. The bentonite distribution can be separated into two parts in North Latvia–South Estonia, indicating the existence of shelf sea currents in the Baltic Silurian Basin

Section: Areal Distribution Of Bentonitesmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

Correlation of upper Llandovery–lower Wenlock bentonites in the När (Gotland, Sweden) and Ventspils (Latvia) drill cores: role of volcanic ash clouds and shelf sea currents in determining areal distribution of bentonite

Kiipli¹,

Kallaste²,

Nestor³

2012

“…The late Darriwilian-Sandbian interval of elevated P in the basinal sections might have resulted from the revival of upwelling. The time of this upwelling matches between two periods of faster water movements, the Floian-lower Darriwilian southerly current and the westerly late Sandbian current (Kiipli et al 2008(Kiipli et al , 2009. Some indicators, such as the distribution of P-rich rock in Poland (Podhalańska 2002;Trela 2005), point to a possible southerly direction of upwelling.…”

Section: Discussionmentioning

confidence: 95%

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

Kiipli¹,

Kiipli²,

Kallaste³

et al. 2010

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

“…The impoverish-ment of the conodont fauna in the Volkhov Stage may be closely connected with maximal submersion of the Jelgava depression and currents in the deep shelf (Kiipli et al 2009). The Jelgava depression in Latvia came into being in Hunneberg-Billingen time and deepening proceeded up to the end of Kunda time (Männil 1966;Ulst et al 1982).…”

Section: Remarks On Conodont Faunamentioning

confidence: 97%

Lower and Middle Ordovician conodonts from the subsurface of SE Estonia and adjacent Russia

Viira¹

2011

The distribution of conodonts in the Lower–Middle Ordovician beds was studied in five drill core sections of southeastern Estonia. Ten conodont zones and six subzones, from the Paroistodus proteus Zone to the Eoplacognathus lindstroemi Subzone, were established. The peculiarity of the studied sequence is that the Volkhov Stage is notably poor in conodonts, in particular Baltoniodus species. Large specimens of Drepanodus arcuatus and Protopanderodus rectus, however, are found in great numbers in the uppermost Volkhov and lower Kunda stages. The deeper shelf conodont faunas recognized in SE Estonia (Central Baltoscandian confacies belt) are compared with shallow shelf faunas of northern Estonia (North Estonian confacies belt)