Sample Detail of
Sample: Sample No. 92AD33-0.2 -- USGS No. 32433-PC
Locality: Field No. 92AD33-0.2
Description: Howard Pass C-3. Measured section extends from 68o 30'40"/157o 31'00" (top) to 68o 30'32"/157o 31'34" (base). Samples at this locality from a 165-m-thick measured section of unit Mlb (upper part); on trend with (and 0.25 mi south of ) section measured by Armstrong (1970). Sample from 3-m-thick interval of >80 percent chert. Collected from less cherty, uppermost 0.5 m of dolostone in 5- to 8-cm-thick beds interlayered with cherty bands (10-15 percent) that preserve crinoidal pack/grainstone texture. Thin section is dolomitized crinoidal packstone. Collected 0.2 m below top of measured section; approx. 30 m below top of unit Mlb. Heavy mineral concentrate: chiefly fluorite, phosphatic brachiopod fragments, conodonts, and lesser ichthyoliths. Section contains brachiopods and rugose corals of late Osagean or Meramecian age, and colonial corals (Lithostrotion (Siphonodendron) sinuosum (Kelly)) and endothyrid foraminifers of Meramecian age (Armstrong, 1970, 1975). (description from Dover et al., 2004, p. 41 (Table 1)).

[Howard Pass C-3. 68°30'43", 157°31'00". Sample from 3 m-thick interval of >80% chert. Collected from less cherty, uppermost 0.5 m of 5-8 cm-thick beds of dolostone with 10-15% cherty bands preserving crinoidal packstone-grainstone texture.
Collected from 0.2 m below top of measured section.
92AD32, 33, 49A, 47 from platformal facies of Lisburne Group at Mt. Bupto, ~1-2 miles east of headwaters of Bushy Creek and ~4 miles southwest of Rim Butte along west side of eastern half of Mount Bupto, western Brooks Range. 92AD32A collected from "Black Lisburne" facies, overlying (structurally and stratigraphically(?) rest of the samples (92AD33, 49, 47). Age of similar rocks at Ivotuk Hills is Chesterian (85ASi14-18).

92AD33-0.2 to -120 from 1240 m and 1100 m elevation of continuously exposed chert and dolostone along trend with measured section of Gus Armstong (<0.25 mile due north), who suggested an age of Meramecian (based on silicified colonial corals and forams) for the upper 100 m (at least) of section (see Armstrong, AAPG Bulletin, v. 54, p. 251+, 1970); N part NE1/4 sec. 9, T. 11 S., R. 24 W, lat. 68°30'43" to 68°30'37", long. 157°31'00" to 20", Howard Pass C-3 quadrangle. (description from Harris E&R report dated March 17, 1995)]
Location: Alaska Quadrangle: Howard Pass C-3
Township&Range: 11 S. 24 W. Section: 9
Lat.: 68o30'40 " Long.: 157o31'34 "
Reference
Title: Geologic and fossil locality maps of the west-central part of the Howard Pass Quadangle and part of the adjacent Misheguk Mountains Quadrangle, western Brooks Range, Alaska ,  2004
Report by: Jim Dover , Irv L. Tailleur , Julie A. Dumoulin
Age: Meramecian (early Late Mississippian (late Meramecian))
Formation: Lisburne Group (Bupto facies of Lisburne Group (Upper and Lower Mississippian))
CAI:Min: 1.5
Comment:Age: early Late Mississippian (late Meramecian) based on stratigraphic position above 92AD33-30.

Biofacies: Bispathodid-kladognathid: open-marine, outer shelf (platform) or deeper water depositional environment (based on absence of cavusgnathids and common hindeodids and synclydognathids).

Shown as locality 71 on Sheet 2; map unit: Mlb

CAI=1.5

Processed 10.5 kg of rock. This is an extremely abundant sample; only part of the +60 mesh nonmagnetic heavy-mineral concentrate was picked.

Occurrence(s)
No. Group Name Qty Notes
1 Conodonts Bispathodus utahensis Sandberg and Gutschick 413 Pa, 37 Pb, and 8 Sc elements All conodonts identified by A.G. Harris
2 Conodonts 2 incomplete Pa elements Embsaygnathus sp. indet.
3 Conodonts 1 juvenile Pa element Gnathodus sp. indet.
4 Conodonts Hindeodus cristulus (Youngquist and Miller), 2 Pa and 3 Pb elements
5 Conodonts Idioprioniodus conjunctus (Gunnell), 7 Pa, 1 Pb, 5 M, 3 Sa, and 1 Sb elements
6 Conodonts Kladognathus tenuis (Rexroad), 67 P, 102 M, 16 Sa, and 147 Sb-Sc elements
7 Conodonts Synclydognathus geminus (Hinde), 1 Pa and 5 S elements
8 Conodonts 34 Pa Vogelgnathus postcampbelli (Austin and Husri)
9 Conodonts Unassigned elements: 3 Pb (2 morphotypes), and 2 Sc
10 Conodonts +200 indet. bar, blade, and platform fragments

Title: Report on Referred Fossils ,  1995 (03/17)
Analysis of all samples is given in the accompanying 16-page table. The range of biostratigraphically important samples is shown on the accompanying diagram. The heavy-mineral concentrates were analyzed by Nancy Stamm; the residues have been returned to Julie Dumoulin. Please note a few (~4 samples have heavy-mineral concentrates that include chalcopyrite and bornite).
Report by: Anita G. Harris
Referred by: Julie A. Dumoulin , J. H. Dover
Age: Meramecian (Meramecian, probably late Meramecian)
Formation: Lisburne Group
CAI:Min: 1.5
Comment:Age: Meramecian, probably late Meramecian and definitely late Meramecian if this sample is stratigraphically above 92AD33-30.
Biofacies: Bispathodid-kladognathid open-marine, outer shelf (platform) or deeper water depositional environment (absence of cavusgnathids and common hindeodids and synclydognathids.

CAI = 1.5

10.5 kg of rock processed (320 g +20 mesh and 182 g 20-200 mesh insoluble residue).
Heavy-mineral concentrate: chiefly fluorite (phosphatic brachiopod fragments, conodonts, and phosphatized argillaceous grains and lesser ichthyoliths(?).

Occurrence(s)
No. Group Name Qty Notes
1 Conodonts This is an extremely abudant sample; only part of the +60 mesh nonmagnetic heavy-mineral concentrate was picked.
2 Conodonts Bispathodus utahensis Sandberg and Gutschick 413 Pa, 37 Pb, 8 Sc elements
3 Conodonts 2 incomplete Pa elements Embsaygnathus sp. indet.
4 Conodonts 1 juvenile Pa element Gnathodus sp. indet.
5 Conodonts Hindeodus cristulus (Youngquist and Miller) 2 Pa and 3 Pb elements
6 Conodonts Idioprioniodus conjunctus (Gunnell) 7 Pa, 1 Pb, 5 M, 3 Sa, and 1 Sb elements
7 Conodonts Kladognathus tenuis (Rexroad) 67 P, 102 M, 16 Sa, and 147 Sb-Sc elements
8 Conodonts Synclydognathus geminus (Hinde) 1 Pa and 5 S elements
9 Conodonts 34 Pa Vogelgnathus postcampbelli (Austin and Husri)
10 Conodonts UNASSIGNED ELEMENTS:
11 Conodonts 3 Pb (2 morphotypes), 2 Sc
12 Conodonts +200 indet. bar, blade, and platform fragments