scholarly journals Age and genesis of the White Pine stratiform copper mineralization, northern Michigan, USA, from paleomagnetism

Geofluids ◽  
2013 ◽  
Vol 13 (2) ◽  
pp. 112-126 ◽  
Author(s):  
D. T. A. Symons ◽  
K. Kawasaki ◽  
J. F. Diehl
Keyword(s):  
White Pine ◽  
Copper Mineralization ◽  
Northern Michigan

Paleomagnetism of the native copper mineralization, Keweenaw Peninsula, Michigan

2019 ◽  
Vol 56 (9) ◽  
pp. 932-947 ◽  
Author(s):  
D.T.A. Symons ◽  
K. Kawasaki
Keyword(s):  
Remanent Magnetization ◽  
White Pine ◽  
Native Copper ◽  
Time Limits ◽  
Clastic Rocks ◽  
Copper Mineralization ◽  
Lake Formation ◽  
World Class ◽  
Keweenaw Peninsula ◽  
Basaltic Flow

The age and genesis of Michigan’s world-class native copper deposits are poorly constrained. The copper is hosted by basaltic flow tops and conglomeratic interbeds of the 1095 ± 2 Ma Keweenawan Portage Lake Formation. Progressive thermal demagnetization isolates stable hematite remanent magnetization components at 28 paleomagnetic sites. Paleomagnetic tilt tests show that magnetite in massive flow interiors is primary (1095 ± 2 Ma) and that hematite throughout the formation is syntectonic. The altered cupriferous deposits contain primary ∼1095 Ma and secondary ∼1053 Ma hematite in various proportions. The Caledonia Mine’s basaltic mineralization carries the ∼1053 Ma hematite dominantly whereas the Delaware Mine’s conglomeratic interbed mineralization carries the ∼1095 Ma hematite dominantly. The ∼1095 Ma hematite is attributed mostly to magnetite exsolution during flow extrusion and to weathering oxidation between extrusion events. An infusion of epigenetic hydrothermal fluids emplaced the native copper with additional hematite and polarity self-reversing titanohematite at 1053 ± 7 Ma. Importantly, paleomagnetic evidence supports a 1053 ± 7 Ma age also for the White Pine stratiform sedimentary copper mineralization, for the oxidation of the Oronto Group clastic rocks to red beds, and for the time limits of major tectonic uplift and deformation on the Keweenaw Peninsula.

A hydrogeologic model of stratiform copper mineralization in the Midcontinent Rift System, Northern Michigan, USA

Geofluids ◽  
2004 ◽  
Vol 4 (1) ◽  
pp. 1-22 ◽  
Author(s):  
J. B. Swenson ◽  
M. Person ◽  
J. P. Raffensperger ◽  
W. F. Cannon ◽  
L. G. Woodruff ◽  
...  
Keyword(s):  
Rift System ◽  
Midcontinent Rift ◽  
Copper Mineralization ◽  
Midcontinent Rift System ◽  
Northern Michigan
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