Kukpowruk River 96-27 (Cretaceous to of the United States)

Also known as Kukpowruk River/Cape Lisburne floras

Where: western North Slope County, Alaska (69.3° N, 162.6° W: paleocoordinates 79.1° N, 95.7° W)

• coordinate stated in text

• outcrop-level geographic resolution

When: Corwin Formation, Albian to Albian (113.0 - 93.9 Ma)

• middle Albian to Cenomanian

• group of beds-level stratigraphic resolution

Environment/lithology: "floodplain"; mudstone and sandstone

• Description. Two coals separated by grey silty mudstone. Each coal

•is approximately 1 m thick. A grey siltstone with an incipient

•nodular texture overlies the upper coal and this contains an impression

•of an upright tree approximately 25–30 cm in diameter. This

•tree appears to be rooted in the siltstone. Above the tree is a fine

•grey/yellow, cross-bedded sandstone with abundant woody debris,

•including drifted coalified logs, and several prominant pebble

•stringers. The sandstone is approximately 5 m thick with no obvious

•well-developed ripples or burrows. This passes up into a series of

•interbedded grey/brown mudstones and thin sandstones. These

•mudstones and thin sandstones contain abundant large-leafed

•ginkoes and Desmiophyllum. Ferns are rare. Equisetites is apparently

•absent. Silty mudstones contain numerous ironstone nodules with

•Desmiophyllum, Podozamites and fern fragments.

•The coal beds are traceable across the river to the northeast where

•they are exposed stratigraphically below locality 96-26. Here the

•sequence continues upwards towards the axis of Howard Syncline

•with interbedded grey, silty mudstones and grey to orange/yellow

•weathering, fine-grained sandstones. Sandstones contain Equisetites

•rhizomes, Desmiophyllum, and vertical and horizontal, sometimes

•branched, mud-filled burrows approximately 1 cm in diameter (not

•U-shaped). This sequence passes up into more carbonaceous-rich

•mudstones with iron nodules and then to a coal more than 1.5 m

•thick. This coal is covered by grey mudstones containing ironstone

•nodules in bands. The ironstones yielded some sparse ginkgoes,

•abundant Desmiophyllum, scarce Pagiophyllum triangulare, Birisia, cf.

•Arctopteris/Cladophlebis, branchwood, some cones and a very largeleafed

•Pseudocycas sp. cf. P. unjiga. Equisetites is common in overlying

•fine- to medium-grained, grey sandstones with abraded wood

•fragments on some bedding planes. Above this 1.5-m-thick

•sandstone is a thin weathered bentonite approximately 5 cm thick.

•Interpretation. Floodplain interfluves with mires, near-channel

•crevasse splays and channel sands. The channel influence wanes

•upsection and there is a return to predominantly interfluve

•depositional environments.

Size class: macrofossils

Collection methods: quarrying,

• Material stored at the Earth Sciences Department, The Open University, collection # 96 RAS.

Primary reference: R. A. Spicer and A. B. Herman. 2001. The Albian-Cenomanian flora of the Kukpowruk River, western North Slope, Alaska: stratigraphy, palaeofloristics, and plant communities. Cretaceous Research 22:1-40 [D. Royer/D. Royer/D. Royer]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 34387: authorized by Dana Royer, entered by Dana Royer on 28.08.2003

Creative Commons license: CC BY (attribution)

Taxonomic list

Peltaspermopsida
 Peltaspermales - Peltaspermaceae
? Sphenobaiera sp. Florin 1936
Pinopsida
 Pinales - Podocarpaceae
Podozamites spp. Braun 1843
occurs in ironstone nodules within mudstones
 Pinales -
Desmiophyllum sp. Lesquereux 1878
occurs in ironstone nodules within mudstones