Kukpowruk River 96-4 (Cretaceous to of the United States)

Also known as Kukpowruk River/Cape Lisburne floras

Where: western North Slope County, Alaska (68.8° N, 163.2° W: paleocoordinates 78.8° N, 98.2° 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: wet floodplain; coal and carbonaceous shale

• Description. Alternating coals, carbonaceous shales, siltstones and

•fine-grained sandstones were exposed in large bluffs. Two prominent

•yellow/grey fine-grained sandstones occur near the top of the

•exposure. Podozamites was found in all lithologies but was sparse in

•fine sands where Ginkgo predominated. Ginkgo was rare in other

•lithologies. Pityophyllum ex gr. nordenskiodii and P. ex gr. staratschinii

•were most frequent in coaly units, whereas abundant large-leaved

•Podozamites commonly occurred as a monodominant taxon in

•bright yellow- or orange-weathering ironstone nodules in carbonaceous

•shales. Equisetites, Birisia alata, Podozamites and Ginkgo ex gr.

•adiantoides were found in the more sandy sediments. Coals up to

•1 m thick were sub-bituminous. Abundant compressed logs, up to

•0.5 m diameter, occur parallel to bedding through the section.

•However, some logs were almost circular indicating early mineralization.

•Calcite and iron minerals permeated all the wood, but the

•growth of calcite crystals enlarged the tracheids and destroyed

•the structure.

•Interpretation. This locality reveals the youngest rocks exposed along

•the river in the Coke Basin syncline. It represents heavily vegetated,

•predominantly interfluve and wooded floodplain environments, including mires subsequently inundated by near channel sediments.

•There appears to be a facies-related heterogeneity in species distribution

•with Pityophyllum producers dominating the stable mires,

•Podozamites producers in slightly more clastic-influenced swamps,

•and Ginkgo associated with the near-channel disturbed sites.

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 33500: authorized by Dana Royer, entered by Dana Royer on 01.08.2003

Creative Commons license: CC BY (attribution)

Taxonomic list

unclassified
  -
Birisia alata
found in more sandy sediments
Polypodiopsida
 Equisetales - Equisetidae
Equisetites ex gr. burejensis
found in more sandy sediments
  -
Cladophlebis sp. Brongniart 1849
Ginkgoopsida
 Ginkgoales - Ginkgoaceae
Ginkgo ex gr. adiantoides Unger 1845 ginkgo
found in more sandy sediments; dominates in fine sands, rare in other lithologies; does not co-occur with Podozamites
Gnetopsida
  -
"Pityophyllum ex gr. staratschinii" = Pityophyllum staratschini, "Pityophyllum ex gr. nordenskioldii" = Pityophyllum nordenskioeldi
"Pityophyllum ex gr. staratschinii" = Pityophyllum staratschini Nathorst 1899
most frequent in coaly units
"Pityophyllum ex gr. nordenskioldii" = Pityophyllum nordenskioeldi Heer 1899
most frequent in coaly units
 Coniferales - Podocarpaceae
Podozamites spp. Braun 1843 podocarp
found in all lithologies but sparse in fine sands where Ginkgo dominates; commonly occurred as a monodominant taxon in bright yellow- or orange-weathering ironstone nodules in carbonaceous shales
Pinopsida
 Pinales - Taxaceae
? Cephalotaxopsis sp. Fontaine 1889 yew