Kukpowruk River 96-17 (Cretaceous of the United States)

Also known as Kukpowruk River/Cape Lisburne floras

Where: western North Slope County, Alaska (69.1° N, 162.7° W: paleocoordinates 79.9° N, 92.7° W)

• coordinate stated in text

• outcrop-level geographic resolution

When: Kukpowruk Formation, Albian (113.0 - 100.5 Ma)

• lower to middle Albian

• group of beds-level stratigraphic resolution

Environment/lithology: crevasse splay; concretionary, brown, gray, silty mudstone and fine-grained, brown, gray sandstone

• Description. Grey/brown siltstones/mudstones with an incipient

•nodular texture, with decimetre scale bedding overlain by finegrained

•cross-bedded and rippled grey/brown sandstones with some

•small bivalves identical to those at locality 96-16. The mudstones

•are abundantly rooted with long Equisetites rhizomes. Birisia is

•common. Both fertile and sterile Arctopteris occurs together with

•Sphenopteris sp. Podozamites is rare but when it occurs the leaves are

•large while Pityophyllum is absent. Three Nilssonia species occurred

•in close proximity in the grey/brown mudstones. Arctopteris,

•Nilssonia, Equisetites and large-leafed Ginkgo are the most common

•taxa at this site. The fern fronds are often minimally fragmented

•although many specimens are preserved not flat on bedding planes,

•but curved or rolled within the poorly bedded sediment.

•Interpretation. Near-channel and possibly near-marine overbank

•environment periodically, but not frequently, invaded by sediment.

•The flora appears to represent a later successional stage of community

•development than that seen in the exposure at locality

•96-11. Sediments were extensively bioturbated by roots suggesting

•the vegetation was well established. Woody taxa are in a minority

•and no large woody remains were seen. The succession may

•have begun with an Equisetum/Birisia marsh but this community

•was subsequently invaded by a diversity of ferns, cycadophytes

•and ginkgoes. Salinity may have played a lesser role in determining

•community composition compared to the Birisia marsh of

•locality 11.

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 34300: authorized by Dana Royer, entered by Dana Royer on 26.08.2003

Creative Commons license: CC BY (attribution)

Taxonomic list

unclassified
  -
Birisia alata
common in mudstones
Arctopteris aff. kolymensis
fertile and sterile parts occur together with Sphenopteris sp.
Arctopteris rarinervis
fertile and sterile parts occur together with Sphenopteris sp.
Arctopteris sp.
fertile and sterile parts occur together with Sphenopteris sp.
Pinopsida
 Pinales - Podocarpaceae
Podozamites spp. Braun 1843
large-leaved; rare
 Pinales -
Equisetopsida
 Equisetales - Equisetaceae
Equisetites ex gr. burejensis
rhizomes, long; abundant in mudstones
Cycadopsida
 Cycadales -
"Nilssonia magnifolia" = Nilsonia, "Nilssonia menneri" = Nilsonia, "Nilssonia cf. decursiva" = Nilsonia, "Nilssonia cf. serotina" = Nilsonia
"Nilssonia magnifolia" = Nilsonia cycads
abundant; occurs in close proximity to other Nilssonia in mudstones
"Nilssonia menneri" = Nilsonia cycads
abundant; occurs in close proximity to other Nilssonia in mudstones
"Nilssonia cf. decursiva" = Nilsonia cycads
abundant; occurs in close proximity to other Nilssonia in mudstones
"Nilssonia cf. serotina" = Nilsonia cycads
abundant; occurs in close proximity to other Nilssonia in mudstones
Pteridopsida
 Cyatheales - Dicksoniaceae