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Kukpowruk River

Introduction Geology     Kukpowruk Unassigned Fossils Fossil Images

 

The map on the right shows the localities along the Kukpowruk River sampled both by Smiley (reported in Smiley 1969a), Spicer and Herman (1996) and by Bob and Andrew Spicer in 1998. Click on the locality numbers to see further details of the sites and the fossil floras.

 

Map of Kukpowruk River Hotspot linking to Kukpowruk 98RAS17 Hotspot link to Smiley Section C page Link to Map of Smiley's Kukpowruk section D Hotspot linking to page describing Kukpowruk 96 locality 1 Hotspot linking to page describing Kukpowruk 96 locality 2 Hotspot linking to page describing Kukpowruk 96 locality 3 Hotspot linking to page describing Kukpowruk 96 locality 4 Hotspot linking to page describing Kukpowruk 96 locality 5 Hotspot linking to page describing Kukpowruk 96 locality 6 Hotspot linking to page describing Kukpowruk 96 locality 7 Hotspot linking to page describing Kukpowruk 96 locality 8 Hotspot linking to page describing Kukpowruk 96 locality 9 Hotspot linking to page describing Kukpowruk 96 locality 10 Hotspot linking to page describing Kukpowruk 96 locality 11 Hotspot linking to page describing Kukpowruk 96 locality 12 Hotspot linking to page describing Kukpowruk 96 locality 13 Hotspot linking to page describing Kukpowruk 96 locality 14 Hotspot linking to page describing Kukpowruk 96 locality 15 Hotspot linking to page describing Kukpowruk 96 locality 16 Hotspot linking to page describing Kukpowruk 96 locality 17 Hotspot linking to page describing Kukpowruk 96 locality 18 Hotspot linking to page describing Kukpowruk 96 locality 19 Hotspot linking to page describing Kukpowruk 96 locality 20 Hotspot linking to page describing Kukpowruk 96 locality 21 Hotspot linking to page describing Kukpowruk 96 locality 22 Hotspot linking to page describing Kukpowruk 96 locality 23 Hotspot linking to page describing Kukpowruk 96 locality 24 Hotspot linking to page describing Kukpowruk 96 locality 25 Hotspot linking to page describing Kukpowruk 96 locality 26 Hotspot linking to page describing Kukpowruk 96 locality 277 Hotspot linking to Kukpowruk 98RAS16 Hotspot linking to Kukpowruk 98RAS17 Hotspot linking to Kukpowruk 98RAS18 Hotspot linking to Kukpowruk 98RAS19 Hotspot linking to Kukpowruk 98RAS20 Hotspot linking to Kukpowruk 98RAS21 Hotspot linking to Kukpowruk 98RAS22

sedimentray log of the section at Kukpowruk 96 locality 2

Sedimentary log of the section exposed at 96-2 on the Kukpowruk River, western North Slope, Alaska. see the panel to the left for Unit descriptions. The log is based on the sedimentray succession exposed to the right of the fault as seen in the field photograph below.

Locality 96-2:   68° 49' 11" N  162° 10' 38" W

Corwin Formation

Specimens: 96 RAS 22, 23, 24, 25

Description. Cut bank forming good exposures (see field photo below).
           

Unit 1. At the base of the exposed section carbonaceous mudstones contain the lowermost reference unit used here which consists of an olive gray indurated siltstone. (1 m thick).

Unit 2.  Carbonaceous shale/mudstone, rich in small Podozamites leaves and rare Pityophyllum leaves. (About 1.5 m thick). The basal mudstone, together with units (1) and (2) make up a sedimentary package visually estimated to be at least 10 m thick.

Unit 3. Yellow-weathering gray siltstones and fine sands with a crumbly texture containing abundant Equisetites rhizomes, Podozamites fragments, branch wood and small compressed logs aligned parallel to bedding. Occasional small tree stumps, a few decimetres in diameter, occurred normal to bedding and were rooted in the underlying mudstone. (Approximately 2.5 - 3 m thick).

Unit 4. Poor coal bearing numerous ironstone nodules and thin sandy layers, abundant logs, branchwood, and Podozamites leaves. Pityophyllum is also present but less abundant. (4 - 5 m thick).

Unit 5. Olive gray siltstone containing numerous nodular and sheet form ironstone concretions. (0.7 m thick).

Unit 6. A thin coal within which was rooted a small (approximately 20 cm diameter) upright trunk. (0.7 m thick).

Unit 7. Coarsening upward, yellow/orange weathering gray siltstone rich in Podozamites fragments. (2 m thick). A small tree trunk protruded upwards in to this unit for approximately 1 m.

Unit 8. Succession of three thin (< 0.5 m) poor coals, often with ironstone concretions, separated by olive gray siltstones. (Approximately 3 m thick).

Unit 9. gray, weathering to olive gray/yellow, fine sandstone. (1.5 - 2 m thick).

Unit 10. Poor coal with ironstone nodules (approximately 0.5 m thick).

Unit 11. Olive gray to brown fine silts with a thin, poorly developed coal in the lower third above which there are occasional (up to four) white indurated bands. (8 - 9 m thick).

Unit 12. Thin very poor coal (<0.3 m thick).

Unit 13. Yellow-weathering gray well bedded siltstones and fine sands forming a series of three fining upward cycles. (Estimated to be up to 12 m thick).

At the bend in the river a high angle normal fault (see field photograph below), of unknown throw, had brought down blocky, cross bedded, olive gray siltstones and sandstones rich in Podozamites, Ginkgo ex gr. adiantoides, rare Birisia, Equisetites, Pityophyllum ex gr. staratschinii, and compressed logs. Ginkgo predominated in the sandier beds, while Podozamites  was most common in the silts. These beds are moderately contorted and overly, apparently with an erosional contact, underlying yellow/gray sands and silts that dip at approximetely 45° to the west.

Interpretation: Interfluve well-vegetated environments with lacustrine, crevasse splay and mire deposits. Podozamites was largely ubiquitous but particularly abundant in mires subject to some clastic influence. Pityophyllum co-ocurred in the mires but was apparently subordinate to Podozamites. Ginkgo was more frequent in near channel, more disturbed settings.

 

Below: Field photograph of the Kukpowruk 96-2 section.

 

Field photo of the Kukpowruk 96-2 section.

Hotspot link to Smiley Section C page Link to Map of Smiley's Kukpowruk section D