GEOLEX

Summary of Citation: Grand Canyon

Publication:
Walcott, C.D., 1883, Pre-Carboniferous strata in the Grand
   [Canyon] of the Colorado, Arizona: American Journal of Science,
   3rd series, v. 26, p. 437-442

Usage in Publication:
Grand [Canyon] group*

Modifications:	Geologic Province:	Dominant Lithology:
First used	Southern Rocky Mountain region	Sandstone Greenstone Limestone Lava

Summary:
First published use of name. [Canyon spelled Canon with a tilde over the n in this report.] Name attributed to Powell. No type locality designated. Considered as a group beneath the Chuar group (first used) and above the eroded and upturned edges of Archean quartzite and flesh-colored granite. Consists of sandstone and greenstone in the Grand Canyon of AZ in the Southern Rocky Mountain region. At the summit of the Grand Canyon group is a 100 ft thick massive magnesian limestone above the red sandstone. One flow of lava 150 ft thick present near base. [Thickness of group not clearly stated.] Assigned to the Early Cambrian. Thought to be the same in part as the Keweenawan series of WI. Columnar section shown on p. 484 illustrates relationship of Tonto sandstone to Chuar and Grand [Canyon] groups.

Summary of Citation: Grand Canyon

Publication:
Walcott, C.D., 1894, Pre-Cambrian igneous rocks of the Unkar
   terrane, Grand Canyon of the Colorado, Arizona: U.S. Geological
   Survey Annual Report, 14, pt. 2, p. 503-519

Usage in Publication:
Grand Canyon group*

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

Summary:
Strata above the "Great unconformity" at the top of the Vishnu [schist] and below the unconformity at the base of the Tonto sandstone assigned to the Grand Canyon group (or series) in this report on northern AZ, Southern Rocky Mountain region. This definition is the same as the one used by Powell (1876). The group is divided into the Chuar terrane at base and the Unkar terrane (new) at the top. Between the time when the Grand Canyon group was named (Powell, 1876) and this report, the name Grand Canyon was applied by author only to rocks called Unkar in this report. Measured section 5,120 ft thick of Chuar at Nankoweap Butte described. Measured section 6,830 ft thick of Chuar in cliffs on north side of Unkar Valley described. Unnamed lava beds within the Grand Canyon group on north side of Unkar valley. May be the same age as the Keweenawan series of the Lake Superior area and the Llano series of TX. Algonkian age.

Summary of Citation: Grand Canyon

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:
Grand Canyon Supergroup*

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

Summary:
The Precambrian Grand Canyon Series of Walcott (1894) consists of three major distinct units: Unkar Group at base, Nankoweap Formation, and Chuar Group. Series is redesignated as Grand Canyon Supergroup in conformance with the ASC, art. 9e. Unconformably overlies Vishnu Schist. Unconformably underlies Tapeats Sandstone. Geologic maps.

Summary of Citation: Grand Canyon

Publication:
Elston, D.P. and McKee, E.H., 1982, Age and correlation of the
   late Proterozoic Grand Canyon disturbance, northern Arizona:
   Geological Society of America Bulletin, v. 93, no. 8, p.
   681-699

Usage in Publication:
Grand Canyon Supergroup*

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

Summary:
Is a Proterozoic unit in Grand Canyon area, northern AZ in the Southern Rocky Mountain region. Revised in that Sixtymile Formation removed from the Chuar Group and considered as the upper formation of the supergroup unassigned to a group. Chuar restricted to the lower two formations--the Galeros (base) and Kwagunt (top). Stratigraphic figures; cross section.

Summary of Citation: Grand Canyon

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:
Grand Canyon Supergroup

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

Summary:
Dox Sandstone, middle formation of Unkar Group of Grand Canyon Supergroup, changed to Dox Formation because it is composed of diverse lithologies (siltstone, shale, dolomite, conglomerate) as well as sandstone. Dox divided into Escalante Creek (base), Solomon Temple, Comanche Point, and Ochoa Point Members, all newly named in the eastern Grand Canyon of the Colorado River, Coconino Co, AZ, Southern Rocky Mountain region. [Term Grand Canyon Supergroup not used in report.] Geologic map. Of late Precambrian age.

Summary of Citation: Grand Canyon

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:
Grand Canyon Supergroup*

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

Summary:
Age changed from Middle Proterozoic to Middle and Late Proterozoic. Consists of Middle Proterozoic Unkar Group and Nankoweap Formation, and Late Proterozoic Chuar Group and Sixtymile Formation. Ranges from 3,546 to 4,143 m thick. Deposited with few breaks between 1,250 and 825 Ma. Bounded by "greatest unconformity" at contact of base of supergroup with Vishnu Schist and by "great unconformity" at contact of top of supergroup with Tapeats Sandstone. Lower unconformity marks an approx 425 Ma hiatus. Upper unconformity marks an approx 230 Ma hiatus. Known only from exposures in Southern Rocky Mountain region in eastern and central parts of Grand Canyon of northern AZ; full section of supergroup preserved only at eastern end. Paleomagnetic correlations can be made with Apache Group and Troy Quartzite of central AZ, Uinta Mountain Group of UT and CO, Belt Supergroup of MT, Keweenawan Supergroup of MI, MN, WI, and Sibley Series of Lake Superior region, and Mackenzie Mountains Supergroup of NW, CN. Paleomagnetic data shows that the supergroup almost entirely post-dates accumulation of the Belt. The only permissible paleomagnetic correlation and temporal overlap is between the uppermost normal polarity part of the Pilcher Quartzite at top of Belt and upper part of Bass Limestone. Columnar section.

Summary of Citation: Grand Canyon

Publication:
Elston, D.P. and Clough, G.A., 1993, Paleomagnetic poles from
   the Middle Proterozoic Hazel Formation, Van Horn area, West
   Texas; rotations of a Grenville-deformed terrane and correlations
   with Keweenawan events on craton [abs.]: Geological Society
   of America Abstracts with Programs, v. 25, no. 1, South-Central
   Section, 27th Annual Meeting, Fort Worth, TX, March 15-16,
   1993, p. 9

Usage in Publication:
Grand Canyon Supergroup*

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

Summary:
Comparison made of paleomagnetic poles and polar paths of Middle Proterozoic rocks of Hazel Formation of Van Horn area, TX (Southwestern Basin-and-Range region) with Middle Proterozoic rocks elsewhere in North America. Changes in direction of apparent polar wander are interpreted to reflect plate interactions and collisions responsible for episodes of deformation on the craton. Folding phases in Van Horn and Adirondack Mountain regions are relatable to 5 direction changes of polar wander between about 1,200 and about 1,000 Ma. Hazel accumulated during an episode of south-to-north thrust faulting that has been identified as belonging to Grenville Orogeny. Hazel is a 1,500 ft thick, moderately to little deformed, purple-red, fine- to coarse-grained sandstone above Allamoore Formation and beneath Carrizo Mountain Group; is similar to Dox Sandstone, Unkar Group, Grand Canyon Supergroup of AZ (Southern Rocky Mountain region) in lithology and in lack of metamorphism. The lower, lower middle, upper parts of Hazel have normal polarity directions. Three poles from Hazel describe a short, north-south trending trace that appears to have rotated about 30 deg clockwise with respect to apex and upper part of descending leg of Unkar loop. A 30 deg counterclockwise vertical-axis rotation brings Hazel into general coincidence with upper part, middle member of Dox, and with middle and early late Keweenawan poles from Lake Superior region.

Summary of Citation: Grand Canyon

Publication:
Elston, D.P., 1993, Middle and early Late Proterozoic Grand
   Canyon Supergroup, northern Arizona, IN Link, P.K., ed.,
   Middle and Late Proterozoic stratified rocks of the western
   U.S. Cordillera, Colorado Plateau, and Basin and Range
   province, Chapter 6, OF Reed, J.C., Jr., and others, eds.,
   Precambrian; conterminous U.S.: Geological Society of America,
   The Geology of North America, The Decade of North American
   Geology (DNAG), v. C-2, p. 521-529

Usage in Publication:
Grand Canyon Supergroup*

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

Summary:
In northern AZ, Southern Rocky Mountain region, Middle-Late Proterozoic boundary is at unconformity between Nankoweap and overlying Chuar Group, both of Grand Canyon Supergroup. Although boundary is placed at unconformity, no appreciable structural disturbance is recognized in Grand Canyon rocks. Nominal age of boundary is 900 Ma. Boundary separates Middle Proterozoic redbed rocks from overlying early Late Proterozoic rocks that record a time of flourishing of plankters and a general suppression of red beds. Middle-Late Proterozoic boundary previously (Elston, 1979, USGS Prof. Paper 1092; Elston, McKee, 1982) drawn to correspond with Grand Canyon-Mackenzie Mountains orogeny at top of Grand Canyon Supergroup to which nominal age of 800 Ma was assigned; this disturbance now is considered to separate early from late Late Proterozoic rocks. Middle and Late Proterozoic age.