thumbnail

Paleomagnetism of the Middle Proterozoic Electra Lake Gabbro, Needle Mountains, southwestern Colorado

Journal of Geophysical Research B: Solid Earth

By:
,

Links

  • The Publications Warehouse does not have links to digital versions of this publication at this time

Abstract

The Electra Lake Gabbro is a small 1.435 Ga pluton that intrudes 1.7 to 1.6 Ga gneisses and schists of the Needle Mountains in southwestern Colorado. Paleomagnetic samples were collected from the main phases of the gabbro, diabase dikes, granite, and alaskite dikes that cut the gabbro and from a partially melted zone in gneiss along the southern margin of the pluton. Gabbro, diabase, and some melt zone samples have a single-polarity characteristic magnetization of northeast declination (D) and moderate negative inclination (I). Demagnetization behavior and rock magnetic characteristics indicate that the remanence is carried by nearly pure magnetite. After correction for the minor west dip of overlying Paleozoic strata, we obtain a mean direction of D = 32.1??, I = -41.9?? (k = 94, ??95 = 3.3??, N = 21 sites) and a paleomagnetic pole at 21.1?? S, 221.1 ??E, (K= 89, A95 = 3.4??). This pole is similar to poles from the Middle Proterozoic Belt Supergroup but is located at a higher southerly latitude than poles from other 1.47-1.44 Ga plutons from North America, most of which plot at equatorial latitudes. The reason for this discrepancy is not clear but may result from a combination of factors, including unrecognized tilting of the gabbro, the failure of this relatively small pluton to fully average paleosecular variation, and uncertainties in the overall reliability of other 1.5-1.4 Ga poles of the North American apparent polar wander path.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Paleomagnetism of the Middle Proterozoic Electra Lake Gabbro, Needle Mountains, southwestern Colorado
Series title:
Journal of Geophysical Research B: Solid Earth
Volume
103
Issue:
7
Year Published:
1998
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
15497
Last page:
15507
Number of Pages:
11