Algae, calcitarchs and the Late Ordovician Baltic limestone facies of the Baltic Basin

Abstract

The Late Ordovician succession of the Baltic Basin contains a characteristic fine-grained limestone, which is rich in calcareous green algae. This limestone occurs in surface outcrops and drill-cores in an extensive belt reaching from Sweden across the Baltic Sea to the Baltic countries. This limestone, which is known in the literature under several different lithological names, is described and interpreted, and the term "Baltic limestone facies" is suggested. The microfacies, from selected outcrops from the Åland Islands, Finland and Estonia, consists of calcareous green algae as the main skeletal component in a bioclastic mudstone-packstone lithology with a pure micritic matrix. Three types of calcitarch, which range in diameter from c. 100-180 μm, are common. Basinward, the youngest sections of the facies belt contain coral-stromatoporoid patch reefs and Palaeoporella-algal mounds. The Baltic limestone facies can be interpreted as representing the shallow part of an open-marine low-latitude carbonate platform.

On the enigma ofPalaenigma wrangeli(Schmidt), a conulariid with a partly non-mineralized skeleton

“…This seems to support the idea that conulariids and P. wrangeli shared general habitat preferences and /or preservation pattern. Based on the specimens available for this study, P. wrangeli and the Late Ordovician conulariids of the eastern Baltica basin occur preferentially in depositional settings within an originally extraordinarily faunal-rich, calcareous soft substrate habitat (see references in section “Material”, and Toom, Vinn & Hints, 2019 ; Kröger et al, 2019 ) for evidence of widespread calcareous soft substrate at P. wrangeli occurrences).…”

“…The rich fauna of the quarry needs a detailed taxonomic examination. The Saunja Formation is more than 10 m thick at Sutlema and consists of a bioturbated, massively bedded, light-colored mud-wackestone, typical for the Baltic Limestone Facies ( Kröger et al, 2019 ).…”

Peer Review #1 of "On the enigma of Palaenigma wrangeli (Schmidt), a conulariid with a partly non-mineralized skeleton (v0.1)"

“…The rich fauna of the quarry needs a detailed taxonomic examination. The Saunja Formation is more than 10 m thick at Sutlema and consists of a bioturbated, massively bedded, light-colored mud-wackestone, typical for the Baltic Limestone Facies (Kröger et al, 2019). Three additional specimens come from drillcores, with little information on co-occurring fauna: Specimen GIT 655-1 was collected from Kükita 24 drillcore (58°48'18.9"N 26°56'32.5"E), c. 4 km south of Mustvee, Mustvee Parish, west of Lake Peipsi, north-east Estonia, from depth 84.35 m, Tudulinna Formation, Vormsi Stage.…”

“…This seems to support the idea that conulariids and P. wrangeli shared general habitat preferences and /or preservation pattern. Based on the specimens available for this study, P. wrangeli and the Late Ordovician conulariids of the eastern Baltica basin occur preferentially in depositional settings within an originally extraordinarily faunal-rich, calcareous soft substrate habitat (see references in section "Material", and Toom, Vinn & Hints, 2019;Kröger et al 2019 for evidence of widespread calcareous soft substrate at P. wrangeli occurrences). Neither the extreme apices of P. wrangeli, nor that of co-occurring conulariids are known.…”

Investigation of Petrographic and Diagenetic Properties of Asmari Reservoir Cap Rock, SW Iran

“…Limestones constitute the largest volume of non-siliceous detrital sedimentary rocks [10]. The limestones in the Ramshir oil field rock are Greenstone, Paxton, Waxton and Madstone according to Dunham Classification (Figures 3C, 3D, 3E, 3A).…”