DX5 Sample 2 (Silurian of the United States)

Where: Iowa (42.1° N, 91.1° W: paleocoordinates 20.1° S, 56.7° W)

• coordinate estimated from map

When: Pterospathodus celloni conodont zone, LaPorte City Formation, Llandovery (443.4 - 433.4 Ma)

• Sample (m) 0,67-0,74

Environment/lithology: lithified, cherty/siliceous limestone

• The base of the LPC is equivalent to the uppermost part of the lower Hopkinton member, and is composed mainly of breccia beds with chert and large limestone interclasts in a slightly sandy mud matrix. The portion of the LPC equivalent to the Farmers Creek Quarry Member contains brecciated chert beds, a bio-dolo-mud- to wackestone with crinoid debris, and bio-mud- to packstones. Chert nodules are scattered throughout. The portion of the LPC equivalent to the Picture Rock Member of the Hopkinton Formation is a green, calcareous shale to mudstone, and the remainder are bio-wacke- to packstones. The portion of the LPC equivalent to the BCQ Member of the Scotch Grove Formation is composed of predominantly mudstones with scattered crinoid debris punctuated by occasional bio-wacke- to packstones with crinoid debris and brachiopod fossils. There are some intervals of argillaceous mudstones and calcareous green shales that are more predominant in the middle of the BCQ equivalent in the GC.

•The BCQ is exposed at the base of the DX5 outcrop and is a bio-dolo-wackestone with occasional chert nodules. The base of the LPC is marked by thinly bedded chert, overlain by a bed of slightly dolomitized crinoidal wackestone with chert nodules (Figure 6).

Size class: microfossils

Primary reference: C. B. T. Waid and B. D. Cramer. 2017. Telychian (Llandovery, Silurian) conodonts from the LaPorte City Formation of eastern Iowa, USA (East-Central Iowa Basin) and their implications for global Telychian conodont biostratigraphic correlation. Palaeontologia Electronica 20(2):1-37 [P. Wagner/P. Wagner]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 191081: authorized by Emilia Jarochowska, entered by Sarah Haegele on 08.01.2018

Creative Commons license: CC BY (attribution)

Taxonomic list

 Panderodontida - Panderodontidae
Panderodus greenlandensis Armstrong 1990 conodont
Panderodus unicostatus Branson and Mehl 1933 conodont
Aulacognathus bullatus Nicoll and Rexroad 1968 conodont
 Ozarkodinida - Kockelellidae