Ouachita Mountains collecting locality P (Cambrian of the United States)

Where: Arkansas (34.7° N, 93.0° W)

• Paleocoordinates: 14.7° N, 114.3° W (Wright 2013)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Elvinia trilobite zone, Collier Shale Formation, Furongian (497.0 - 486.9 Ma)

• bed-level stratigraphic resolution

Environment/lithology: deep subtidal shelf; lithified lime mudstone

• Sheet-form debris flows. -These deposits have a very high ratio of shale matrix to limestone clasts. Actual geometries of the deposits are difficult to assess because the allochthonous mud matrix is very similar to the surrounding autochthonous

•hemipelagic mud. Although the clasts are randomly distributed, their long axes are crudely parallel to the apparent bedding in discrete layers that are tens of centimeters thick, suggesting a sheet-form geometry. Deposits of this type are found at localities B, D, and E and possibly at localities F, K, L, N, and P (see

•Figure 1). Distribution of clasts at locality J suggests a multiple sheet-form flow or thicker debris-flow deposit. Competence of the mud matrix presumably was high enough to completely support clasts as large as the scarce small boulders observed at localities L and J. Common clast textures include micritic, microspar,

•and finely crystalline limestones and some shales. Clastsize is variable from pebbles to small boulders. Evidence of lithification prior to erosion and redeposition as clasts is indicated by angular fracturing and truncation across internal laminations. Deposits of this type probably represent either unconsolidated

•debris over-flow or a more distal facies.

• dark-gray to black limestone clasts [containing fossils] have micritic, microspar, and finely crystalline textures.

Size class: macrofossils

Primary reference: S. R. Hohensee and J. H. Stitt. 1989. Redeposited Elvinia Zone (Upper Cambrian) trilobites from the Collier Shale, Ouachita Mountains, west-central Arkansas. Journal of Paleontology 63(6):857-879 [M. Hopkins/M. Hopkins]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 229198: authorized by Melanie Hopkins, entered by Melanie Hopkins on 20.02.2023

Creative Commons license: CC0 (CC0)

Taxonomic list

Trilobita
 Olenida - Pterocephaliidae
Pterocephalia sanctisabae Roemer 1849 trilobite
Housia vacuna Walcott 1890 trilobite
Pulchricapitus fetosus Hohensee and Stitt 1989 trilobite
 Olenida - Dokimokephalidae
Iddingsia hapsis Hohensee and Stitt 1989 trilobite
Dellea suada Walcott 1890 trilobite
Pseudosaratogia lata Wilson 1951 trilobite
Kindbladia wichitaensis Resser 1942 trilobite
  - Nepeidae
Xenocheilos minutum Wilson 1949 trilobite
 Ptychopariida - Phylacteridae
Aphelotoxon lumaleasa Hohensee and Stitt 1989 trilobite
Cliffia lataegenae Wilson 1949 trilobite
 Ptychopariida - Elviniidae
Irvingella major Ulrich and Resser 1924 trilobite
Artiopoda
 Agnostida - Agnostidae
Kymagnostus harti Hohensee and Stitt 1989
Neoagnostus dilatus Hohensee and Stitt 1989