Abstract

The Soeginina Beds in the Paadla Formation on the island of Saaremaa, western Estonia, are a lower Ludlow (Upper Silurian) sequence of dolostones, marls, and stromatolites. They represent rocks just above the Wenlock/Ludlow boundary, which is distinguished by a major disconformity that can be correlated to a regional regression on the paleocontinent of Baltica. The depositional environments of the Soeginina Beds include a shelfal environment, restricted shallow marine setting, intertidal mudflat and finally a hypersaline supratidal setting. The evidence includes halite crystal molds, oscillation ripples, eurypterid fragments, stromatolites, ostracods, gastropods, Chondrites trace fossils, intraclasts and oncoids. Nautiloid conchs are common, probably because storm currents washed them in. I measured two sections of the Soeginina Beds at Kübassaare, eastern Saaremaa in western Estonia. The beds in one section are virtually horizontal; in the second they are steeply dipping, probably because of Pleistocene glacial ice overpressure. The beds begin with fine-grained dolostone and end with large, well-preserved domical stromatolites. The equivalent section at Soeginina Cliff in western Saaremaa (about 86 kilometers away) has larger oncoids, branching coral fragments, and bigger stromatolites. It is also more heavily dolomitized. These differences indicate that the western Soeginina Cliff was deposited in slightly deeper, less saline waters than those in the east at Kübassaare.

Advisor

Wilson, Mark

Department

Geology

Disciplines

Sedimentology | Stratigraphy

Publication Date

2012

Degree Granted

Bachelor of Arts

Document Type

Senior Independent Study Thesis Exemplar

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© Copyright 2012 Richa N. Ekka