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Time- and Strata-Bound Features of the Michigan Copper Deposits (USA)

  • G. C. Amstutz

Summary

The Lake Superior Copper deposits in the Keweenaw lavas may be explained by a uniform single origin. The congruence analysis in the field, in hand specimens and with the microscope, as well as paragenetic and chemical analyses led to the conclusion that the copper is a comagmatic (contemporaneous) constitutent accumulated in hydromagmatic (deuteric) phases of the Keweenaw basalt magmas. The copper was carried up, in and with the lavas and crystallized in and with the deuteric phases of these lavas. Some parts of these phases escaped into fractures and into overlaying later flows or sediments (mostly porous conglomerates). The hydromagmatic (deuteric) phases show a distinct crystallization sequence in which the native copper occupies a distinct place. The high degree of congruence existing between the compositional variations and the primary lava features (flow lines, layering, breccia generations, dyklets, etc) rules out a later overall redistribution of elements (or minerals) for most of the copper sections. Burial metamorphism may have changed some of the originally basaltic material, but did not upset the stability of the deuteric phases, which are also of a low temperature — low pressure origin.

Keywords

Copper Deposit Hydrous Mineral Native Copper Hydrothermal Vein Normal Basalt 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1977

Authors and Affiliations

  • G. C. Amstutz
    • 1
  1. 1.HeidelbergGermany

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