Sample Detail of
Sample: Sample No. 92ADo274B -- USGS No. 32466-PC
Locality: Field No. 92ADo274B
Description: Howard Pass C-5. Lat. 68o 39'15" N., Long. 158o 46'05" W. Fine-grained, reddish-brown-weathering dolostone interbedded with approx. 50 percent medium-dark-gray, approx. 0.5 -cm-thick (or less) chert layers containing sponge spicules. Thin section is dolomite, crystal mosaic (crystals euhedral to subhedrals; 20-150 microns in diameter) with irregular zones of chert locally rich in siliceous sponge spicules. Rocks here are an unusually carbonate-rich facies of unit lPMap. Lithogically similar to 92ABs180A (loc. 10) and to thin-bedded chert/dolostone at Lisburne Ridge (northeastern Howard Pass 1:250,000 quadrangle). Interbeds of medium- to dark gray chert (92ADo274A) contained corroded fragments of sponge spicules but no identifiable radiolarians. (description from Dover et al., 2004, p. 30 (Table 1)); [Howard Pass C-5. 68°39'17", 158° 46'00". Fine-grained, reddish-brown-weathering dolostone with ~50% medium-dark-gray, ~0.5-cm-thick (or less) chert interlayers containing sponge spicules. Collected from out and adjacent rubble of Mississippian(?) new(?) facies of Lisburne Group, similar to thin-banded chert/dolostone at Lisburne Ridge. Lithology is similar to 92ABS180.
Collected on northwest side of hill 835 m, 0.5 mile south of headwaters of Recon Creek and 2 1/4 miles north of headwaters of Rolling Pin Creek; NW1/4, NE1/4 sec. 19, T. 9 S., R. 29 W. (description from Harris E&R report dated March 17, 1995; shipment no. A-95-3)]
Location: Alaska Quadrangle: Howard Pass C-5
Township&Range: 9 S. 29 W. Section: 19
Lat.: 68o39'15 " Long.: 158o46'05 "
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: Osagean (middle Osagean (lat3e Early Mississippian))
Formation: Akmalik Chert
CAI:Min: 1.5
Comment:Age: late Early Mississippian; within upper part of Sc. anchoralis-Do. latus Zone (middle Osagean).

Biofacies: Indeterminate (too few conodonts); slope or deeper water winnow.

Shown as locality 7 on Sheet 2, map unit: lPMap

CAI: 1.5

Processed 9.6 kg of rock.

Occurrence(s)
No. Group Name Qty Notes
1 Conodonts 2 Pa fragments Bispathodus utahensis Sandberg and Gutschick
2 Conodonts 1 Pa element Gnathodus pseudosemiglaber Thompson and Fellows
3 Conodonts 2 Pa element fragments Gnathodus sp. indet.
4 Conodonts 1 small bar fagment "Hindeodella" segaformis Bischoff s.f.
5 Conodonts 43 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: Osagean (middle Osagean)
Formation: Lisburne Group
CAI:Min: 1.5
Comment:Age: within upper part of Sc. anchoralis-Do. latus Zone (middle Osagean)
Biofacies: Indeterminate (too few conodonts); slope or deeper water winnow.
CAI = 1.5

9.6 kg of rock processed (3700 g of +20 mesh and 263 g 20-140 mesh insoluble residue).
Heavy-mineral concentrate: chiefly dolomite rhombs and minor iron oxides.

Occurrence(s)
No. Group Name Qty Notes
1 Conodonts 2 Pa fragments Bispathodus utahensis Sandberg and Gutschick
2 Conodonts 1 Pa element Gnathodus pseudosemiglaber Thompson and Fellows
3 Conodonts 2 Pa element fragments Gnathodus sp. indet.
4 Conodonts 1 small bar fragment "Hindeodella" segaformis Bischoff s.f.
5 Conodonts 43 indet. bar, blade, and platform fragments