Tectonic context of native copper deposits of the North American Midcontinent Rift System
Document Type
Article
Publication Date
1-1-1997
Abstract
Economic deposits of native copper are an important feature of the Precambrian North American Midcontinent Rift System. The rift was progressively filled by a thick succession of basalt and then red clastic sedimentary rocks from about 1,109 to 1,060 Ma. Regional contraction of the rift at about 1,060 Ma produced faulting, fracturing, folding, and uplift of rocks on the edges of the rift, including transformation of original graben-bounding faults into high-angle reverse faults. Native copper ore deposits are contemporaneous with these faults/fractures that integrated the paleohydrologic system and provided pathways for upward movement and focussing of ore fluids into permeable and porous tops of basalt lava flows and interflow sedimentary rocks. Potential ore fluids were likely generated throughout the tectonic history of the rift by burial of strata and elevated basal heat flow. It is postulated that the coincidence of available "burial" metamorphic fluids, generated via the thermal pulse related to the rifting event, and faults/fractures, generated via regional Grenvillian contraction, provided the critical component in the genetic model of the native copper deposits.
Publication Title
Special Paper of the Geological Society of America
Recommended Citation
Bornhorst, T.
(1997).
Tectonic context of native copper deposits of the North American Midcontinent Rift System.
Special Paper of the Geological Society of America,
312, 127-136.
http://doi.org/10.1130/0-8137-2312-4.127
Retrieved from: https://digitalcommons.mtu.edu/michigantech-p/12296