Porkuni, Siuge Member (Ordovician of Estonia)

Also known as Borkholm

Where: Lääne-Viru, Estonia (59.2° N, 26.2° E: paleocoordinates 26.2° S, 0.3° W)

• coordinate stated in text

• small collection-level geographic resolution

When: Normalograptus extraordinarius graptolite zone, Siuge Member (Ärina Formation), Porkuni (445.6 - 443.7 Ma)

• The Porkuni Regional Stage is formerly known as the "Borkholm'sche Schicht" (Raukas & Teedumäe [eds.] 1997, Geology and Mineral Resources of Estonia, html version, http://sarv.gi.ee/geology). Spinachitina taugourdeaui chitinozoan zone.

• member-level stratigraphic resolution

Environment/lithology: perireef or subreef; lithified, shelly/skeletal lime mudstone and nodular, shelly/skeletal chert

• "North Estonian Confacies Belt at the northern flank of the Livonian Tongue" (Kröger & Isakar, 2006);

•"inter-reef facies" (Raukas & Teedumäe [eds.] 1997, Geology and Mineral Resources of Estonia, html version, http://sarv.gi.ee/geology);

•A more datailed description of environment and setting is given in Kröger (2007).

• "The Siuge Member consists of a succession of roughly 1.5 m slightly dolomitised biomicritic wackestones to micritic bioclastic packstones. The skeletal grains include fragments of crinoids, ostracods, and brachiopods. Grains of quartz only account for less than 10% of the total sediment (Oraspõld 1975). A relatively high content of bitumen is characteristic of the sediments of the Siuge Member. The limestones consist of cross-bedded channel fillings with thin argillaceous interlayers (Fig. 3). Locally, layers or nodules of chert occur at the bottom of the channel structures. The layers with chert nodules have a thickness of less than five centimetres and contain numerous small but macroscopic remains of predominantly bryozoan zooaria, ostracod tests, and echinoderm ossicles. Gastropods, bivalves, graptolites, and cephalopods are less common, but occur in considerable numbers." (Kröger, 2007)

Size class: macrofossils

Preservation: cast, recrystallized, replaced with silica

Collected by M. Isakar, B. Kröger, among others in 2000, 2004, and earlier; reposited in the MfN

• TUG = Tartu Ülikool Geoloogiamuuseum, Tartu, Estonia

•NMB = Museum für Naturkunde Berlin

•The materials "have been collected since the nineteenth century by Wilhelm Dames, Walther Rosenberg (at reposition of NMB), Arwed von Wahl (in collection of GIT), Karl Orviku, and Ülle Sirk. However, the bulk of the material was collected by Mare Isakar (Tartu) and Björn Kröger (stored in the collection of TUG) during two field trips in 2002 and 2004." (Kröger, 2007)

Primary reference: B. Kröger and M. Isakar. 2006. Revision of annulated orthoceridan cephalopods of the Baltoscandic Ordovician. Fossil Record 9(1):137-163 [B. Kröger/B. Kröger/B. Kröger]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 87313: authorized by Björn Kröger, entered by Torsten Liebrecht on 14.03.2009, edited by Pete Wagner and Björn Kröger

Creative Commons license: CC BY (attribution)

Taxonomic list

• I added Koken's Borkholm taxa to this list, as they are from this member of the formation at Porkuni.
Trilobita
 Phacopida - Cheiruridae
"Cheirurus (Pseudosphaerexochus) roemeri" = Pseudosphaerexochus roemeri9
"Cheirurus (Pseudosphaerexochus) roemeri" = Pseudosphaerexochus roemeri9 Schmidt 1881 trilobite
Strophomenata
 Orthotetida - Triplesiidae
Streptis undifera2 Ulrich and Cooper 1936
 Strophomenida - Rafinesquinidae
Rhynchonellata
 Orthida - Draboviidae
Drabovia minuta1 Hints 2012
 Orthida - Rhipidomellidae
 Orthida - Tyronellidae
Tyronella siugensis1 Hints 2012
 Orthida - Wangyuiidae
Sigmelasma peepi1 Hints 2012
Bivalvia
 Cardiida - Cardiidae
Cardium pygmaeum n. sp.3 Hisinger 1837 cockle
Gastropoda
 Euomphalina - Holopeidae
"Anomphalus filosus n. sp." = Holopea filosus6
"Anomphalus filosus n. sp." = Holopea filosus6 Koken and Perner 1925 snail
 Euomphalina - Helicotomidae
Helicotoma superba n. sp.5, "Palaeomphalus gradata" = Palaeomphalus obtusangulus6
Helicotoma superba n. sp.5 Koken 1897 snail
"Palaeomphalus gradata" = Palaeomphalus obtusangulus6 Angelin and Lindström 1880 snail
 Euomphalina - Planitrochidae
"Pycnomphalus borkholmiensis n. sp." = Trochomphalus borkholmiensis5
"Pycnomphalus borkholmiensis n. sp." = Trochomphalus borkholmiensis5 Koken 1897 snail
 Euomphalina - Platyceratidae
"Eunema rupestre" = Cyclonema rupestre6
"Eunema rupestre" = Cyclonema rupestre6 d'Eichwald 1856 snail
 Euomphalina - Craspedostomatidae
Umbonellina infrasilurica n. gen. n. sp.6
Umbonellina infrasilurica n. gen. n. sp.6 Koken and Perner 1925 snail
 Murchisoniina - Eotomariidae
Eocryptaenia singularis n. gen. n. sp.6
Eocryptaenia singularis n. gen. n. sp.6 Koken and Perner 1925 snail
 Murchisoniina - Gosseletinidae
"? Globispira nitida n. sp." = Cataschisma nitida6
"? Globispira nitida n. sp." = Cataschisma nitida6 Koken and Perner 1925 snail
 Murchisoniina - Trochonematidae
Trochonema panderi n. sp.4 Koken 1896 snail
Trochonema minus n. sp.5 Koken 1897 snail
Trochonema peraltum n. sp.5 Koken 1897 snail
 Murchisoniina - Lophospiridae
"Worthenia borkholmiensis n. sp." = Ruedemannia borkholmiensis4, "Worthenia tolli n. sp." = Ruedemannia tolli5, "Worthenia aista n. sp." = Ruedemannia lirata4, "Murchisonia nieszkowskii n. sp." = Ectomaria nieszkowskii10
"Worthenia borkholmiensis n. sp." = Ruedemannia borkholmiensis4 Koken 1896 snail
"Worthenia tolli n. sp." = Ruedemannia tolli5 Koken 1897 snail
"Worthenia aista n. sp." = Ruedemannia lirata4 Ulrich and Scofield 1897 snail
"Murchisonia nieszkowskii n. sp." = Ectomaria nieszkowskii10 Schmidt 1858 snail
 Murchisoniina - Hormotomidae
"Murchisonia meyendorfi n. sp." = Hormotoma meyendorfi5
"Murchisonia meyendorfi n. sp." = Hormotoma meyendorfi5 Koken 1897 snail
Cephalopoda
 Orthocerida - Dawsonoceratidae
Dawsonoceras fenestratum Eichwald 1860
specimens at TUG and NMB
 Orthocerida - Eriditidae
Eriditidae indet.7 Chen in Chen et al 1981
TUG 101/66a, 1227/13, 1227/44, 1227/47 + 1 fragment
 Orthocerida - Orthoceratidae
Orthoceratidae "indet. A"7 McCoy 1844
TUG 1227/1, 1227/9; catalogue numbers of other specimens not given
Orthoceratidae "indet. B"7 McCoy 1844
TUG 1227/2 to 1227/4
 Discosorida - Cyrtogomphoceratidae
Strandoceras orvikui n. sp.7 Kröger 2007
TUG 1227/27 (type), 1227/28 to 1227/30; catalogue number of 5th specimen not given
 Ascocerida - Hebetoceratidae
Parvihebetoceras wahli n. gen. n. sp.7
Parvihebetoceras wahli n. gen. n. sp.7 Kröger 2007
TUG 1227/10 to 1227/12, 1227/13 (type), 1227/41; catalogue numbers of other specimens not given
 Oncocerida - Oncoceratidae
Oncoceratidae indet.7 Hyatt 1884
TUG 1227/37
 Oncocerida - Graciloceratidae
Graciloceratidae "indet. A"7 Flower in Flower and Kummel 1950
TUG 1227/34 to 1227/36
Graciloceratidae "indet. B"7 Flower in Flower and Kummel 1950
TUG 1227/25
Piersaloceras gageli7 Teichert 1930
TUG 1227/32, 1227/38
Porkunioceras tuba n. gen. n. sp.7 Kröger 2007
TUG 1227/24 (type), TUG 1227/26
Pomerantsoceras tibia n. gen. n. sp.7 Kröger 2007
TUG 1227/14 (type), 1227/17, 1227/20; catalogue numbers of other specimens not given