Paleoecology of the Hilliste Formation (Lower Silurian, Llandovery, Rhuddanian) Hiiumaa Island, Estonia: An example of a shallow marine recovery fauna — An abstract submitted to the Geological Society of America for the 2011 annual meeting

July 7th, 2011

KURESSAARE, ESTONIA–Editor’s note: The Wooster Geologists in Estonia found enough material, and had enough time, to write abstracts for posters at the Geological Society of America Annual Meeting in Minneapolis this October. The following is from student guest blogger Rachel Matt in the format required for GSA abstracts:

PALEOECOLOGY OF THE HILLISTE FORMATION (LOWER SILURIAN, LLANDOVERY, RHUDDANIAN) HIIUMAA ISLAND, ESTONIA: AN EXAMPLE OF A SHALLOW MARINE RECOVERY FAUNA

MATT, Rachel M., WILSON, Mark A., FEDORCHUK, Nicholas D., Dept of Geology, The College of Wooster, 944 College Mall, Wooster, OH 44691-2363, VINN, Olev, Dept of Geology, University of Tartu, Ravila 14A, 50411 Tartu, Estonia

The Hilliste Formation (Lower Silurian, Llandovery series and Rhuddanian stage) is well exposed in a quarry in western Estonia. During the deposition of this unit, Estonia was part of the paleocontinent Baltica, which was located near the equator. The Hilliste Formation thus records the recovery of tropical invertebrate marine communities following the mass extinction at the end of the Ordovician. Globally, pre-extinction levels of marine diversity were not met until the Wenlock, about 15 million years after the end of the Ordovician; this formation was deposited about three million years following the event. The Hilliste Formation contains a diverse fauna including brachiopods (orthids, atrypids, rhynchonellids, pentamerids, and strophomenids), corals (favositids, halysitids, heliolitids and rugosans), stromatoporoids, bryozoans, gastropods, crinoids, ostracodes and trilobites. We measured, described and sampled the Hilliste Formation at Hilliste Quarry on Hiiumaa Island, western Estonia. The unit records a regression from depths between normal and storm wavebase to depths at or above normal wavebase. The evidence for this paleoenvironmental interpretation includes more argillaceous beds in the bottom two-thirds of the formation and more biosparite/grainstone upwards. The top third of the formation consists of massive biosparite/grainstone with little clay and overturned and fragmented corals and stromatoporoids indicating high depositional energy. The fauna changes stratigraphically upwards from one dominated by brachiopods and gastropods to a community primarily of corals, stromatoporoids and crinoids. This fauna provides additional information about biotic recovery in eastern Baltica and its implications for the migration of Early Silurian Baltic taxa into other regions.

5 Responses to “Paleoecology of the Hilliste Formation (Lower Silurian, Llandovery, Rhuddanian) Hiiumaa Island, Estonia: An example of a shallow marine recovery fauna — An abstract submitted to the Geological Society of America for the 2011 annual meeting”

  1. Lindsey Bowmanon 08 Jul 2011 at 12:37 pm

    Great job Rachel! It inspires me to work on my own!

  2. […] packed up for our journey back to Hafnarfjordur and started working on our GSA abstracts, which our Estonian colleagues have […]

  3. […] Matt (above) presented her work on the Lower Silurian fauna found in the Hilliste Formation on Hiiumaa Island, Estonia. These fossils are critical evidence for the recovery of marine […]

  4. […] Jonah Novek will be starting his Independent Study project here, building on the labors of Rachel Matt last year. We are all continued to search for crinoids here as part of our joint […]

  5. […] Formation (Lower Silurian, Rhuddanian) on Hiiumaa Island, Estonia. Jonah will be continuing the work begun by Rachel Matt (’12) last year in the Hilliste Quarry a few kilometers east of Käina (N 58.87390°, E 022.97198°). He has […]

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