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Preliminary paleomagnetic poles and correlation of the Proterozoic Uinta Mountain Group, Utah and Colorado

Earth and Planetary Science Letters

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Abstract

Stable paleomagnetic directions have been obtained from seven sites spanning much of the 7-km-thick middle Proterozoic Uinta Mountain Group. The characteristic magnetization is carried partly by detrital(?) and secondary specularite and partly by hematite pigment. Preliminary paleomagnetic poles for six of the seven sites are closely grouped and their mean pole is 0.6??N, 157.2??E (N = 6, ??95 = 5.4??). The pole for the seventh and stratigraphically highest site lies to the west, 4.6??N, 140.1??E, and (n = 8, ??95= 15.9??). On the basis of the poles, revisions to correlations of the Uinta Mountain Group with other sequences are proposed. The Uinta Mountain Group appears to correlate with the Chuar Group and perhaps the upper member of the underlying Nankoweap Formation, and post-dates the Unkar Group of the Grand Canyon Supergroup. In addition, the upper part of the Uinta Mountain Group appears to correlate with the Little Dal Group of the Northwest Territories, Canada. The Uinta Mountain Group appears to entirely post-date the Belt Supergroup of Montana and Idaho. Correlation of the Uinta Mountain Group with the Chuar and Little Dal Groups is supported by the presence of the fossil Chuaria and by apparently overlapping isotopic ages. A maximum age range for the Uinta Mountain Group, extrapolated from the Grand Canyon Supergroup and the Little Dal Group, extends from <1100 to > 770 m.y. ?? 1981.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Preliminary paleomagnetic poles and correlation of the Proterozoic Uinta Mountain Group, Utah and Colorado
Series title:
Earth and Planetary Science Letters
Volume
55
Issue:
1
Year Published:
1981
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
53
Last page:
64
Number of Pages:
12