How does western North Amer have copper and molybdenum ore deposits without a subduction zone?

Posted by admin

Eric asked:

Western North America has many copper and molybdenum ore deposits even though there are no subduction zones to produce them. How can this be explained in terms of plate tectonics?

Thanks.

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3 Responses to “How does western North Amer have copper and molybdenum ore deposits without a subduction zone?”

Xeno Says:
September 5th, 2008 at 12:02 am
Not all copper and Molybdenum deposits are associated with plate boundaries. Many are the result of hydrothermal fluids being released from plutons deep underground. The pressure being released along a fracture zone will allow metal sulfides to precipitate. Or as black smokers under the ocean and being buried by pelitic sediments, later being uplifted and exposed. There are many different ways ore body’s can be formed and they don’t all have to be near a subduction zone.
luka d Says:
September 5th, 2008 at 7:43 pm
flat-slab subduction, crustal thickening, uplift and erosion, and adakitic magmatism coeval with the formation of well-endowed porphyry and/or epithermal mineral provinces.
Laramide thrusting, uplift, intrusions are closely associated with the copper and moly deposits in Colorado and Arizona.
mountaingym Says:
September 5th, 2008 at 9:45 pm
Why do you state they were produced without a subduction zone? What about the Laramide Orogeny and the subduction of the Farallon Plate? Doesn’t this count as a subduction zone? This is how the present day Rocky Mountains got here.