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Geologic Unit: Shinumo

Publication:
Noble, L.F., 1914, The Shinumo quadrangle, Grand Canyon district, 
   Arizona: U.S. Geological Survey Bulletin, 549, 100 p., (incl. 
   geologic map, scale 1:48,000)
Usage in Publication:
Shinumo quartzite*

Modifications: Geologic Province: Dominant Lithology:
 Named
 Southern Rocky Mountain region
 Quartzite
 Sandstone

Summary:
Named as a formation (1 of 5 formations) of Unkar group of Grand Canyon series for Shinumo Creek, north side, Colorado River, Shinumo quad, Coconino Co, AZ in the Southern Rocky Mountain region. No type locality designated. Section 1,564 ft thick measured and described at Shinumo Creek. Composed of purple-brown, white, and green fine-grained sandstone with occasional lenses of conglomerate and thin shale beds and compact white fine, uniform grained quartzite. About one-third of total thickness at Shinumo Creek is sandstone. Cement is generally siliceous, and in places ferruginous. Is most resistant unit of the Grand Canyon series forming cliffs. Overlies Hakatai shale (new) of Unkar group. Underlies Dox sandstone of Unkar group. Of pre-Cambrian age. Geologic map.
Source: GNU records (USGS DDS-6; Denver GNULEX).


Publication:
Elston, D.P., and Scott, G.R., 1976, Unconformity at the 
   Cardenas-Nankoweap contact (Precambrian), Grand Canyon 
   Supergroup, northern Arizona: Geological Society of America 
   Bulletin, v. 87, no. 12, p. 1763-1772.
Usage in Publication:
Shinumo Quartzite*

Modifications: Geologic Province: Dominant Lithology:
 Revised
 Southern Rocky Mountain region
 

Summary:
Unkar Group assigned as the lower group of the Precambrian Grand Canyon Supergroup (new rank; formerly Grand Canyon Series) in the Grand Canyon area of northern AZ in the Southern Rocky Mountain region. Unkar divided into the (ascending): Hotauta Conglomerate, Bass Limestone, Hakatai Shale, Shinumo Quartzite, Dox Sandstone, and Cardenas Lavas. Geologic maps.
Source: GNU records (USGS DDS-6; Denver GNULEX).


Publication:
Stevenson, G.M., and Beus, S.S., 1982, Stratigraphy and depositional 
   setting of the upper Precambrian Dox Formation in Grand 
   Canyon: Geological Society of America Bulletin, v. 93, no. 
   2, p. 163-173.
Usage in Publication:
Shinumo Quartzite

Modifications: Geologic Province: Dominant Lithology:
 Revised
 Southern Rocky Mountain region
 

Summary:
Underlies, as the lowest formation of Unkar Group of Grand Canyon Supergroup, the newly named Escalante Creek Member of Dox Formation (redefined). Shown on geologic map of eastern Grand Canyon, Coconino Co, AZ, Southern Rocky Mountain region. Is of late Precambrian age.
Source: GNU records (USGS DDS-6; Denver GNULEX).


Publication:
Elston, D.P., 1989, Grand Canyon Supergroup, northern Arizona; 
   stratigraphic summary and preliminary paleomagnetic correlations 
   with parts of other North American Proterozoic successions, 
   IN Jenney, J.P., and Reynolds, S.J., eds., Geologic evolution 
   of Arizona: Arizona Geological Society Digest, v. 17, p. 
   259-272.
Usage in Publication:
Shinumo Quartzite*

Modifications: Geologic Province: Dominant Lithology:
 Age modified
 Paleomagnetics
 Overview
 Southern Rocky Mountain region
 

Summary:
Is one of the formations of the Unkar Group of the Grand Canyon Supergroup. Unconformably overlies Hakatai Shale of Unkar. Underlies Dox Sandstone of Unkar. Term "Quartzite" preferred to "Sandstone" because Shinumo is a quartzite at most localities. Is 324 to 475 m thick. Divided into lower, lower middle, upper middle, and upper members. Lower member is fluviatile, possibly tidal flat in origin. Middle member is nearshore marine, tidal flat, and supratidal flat in origin. Upper member deposited as part of mouth bar system in a lower deltaic plain and delta front of a tidal complex. Age changed from Proterozoic Y to Middle Proterozoic, the age term applied to rocks older than 900 Ma and younger than 1,600 Ma. Shown (columnar section) as younger than 1,200 Ma. Paleomagnetic data shows Shinumo correlates with lower part of Keweenawan Supergroup of Lake Superior region. Thought to be a correlative of the Dripping Spring Quartzite. Used in Southern Rocky Mountain region of northern AZ.
Source: GNU records (USGS DDS-6; Denver GNULEX).