Age of native copper mineralization, Keweenaw Peninsula, Michigan

58Citations
Citations of this article
46Readers
Mendeley users who have this article in their library.
Get full text
This PDF is freely available from an open access repository. It may not have been peer-reviewed.

Abstract

Amygdaloidal flood basalts and conglomerates are the host for substantial deposits of native copper within the Portage Lake Volcanics in the Keweenaw Peninsula of Michigan. A wide variety of gangue minerals are associated with the regional hydrothermal alteration- mineralization event. Application of the Rb-Sr method to amygdule-filling microcline, calcite, epidote, and chlorite suggests an age of mineralization between 1,060 and 1,047 m.y. (± 20 m.y.). These results are supported by a fission track age on epidote of 1,044 ±169 m.y. The age of native copper mineralization determined in this study is consistent with geologic evidence which suggests that mineralization postdated the deposition of most or all of the overlying Freda Sandstone. Variable initial 87Sr/86Sr ratios between the low Rb/Sr phases suggest mixing of isotopically distinct sources of Sr during the generation and equilibration of the hydrothermal solutions.

Cite

CITATION STYLE

APA

Bornhorst, T. J., Paces, J. B., Grant, N. K., Obradovich, J. D., & Huber, N. K. (1988). Age of native copper mineralization, Keweenaw Peninsula, Michigan. Economic Geology, 83(3), 619–625. https://doi.org/10.2113/gsecongeo.83.3.619

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free