US EPA

8803338 

Book/Book Chapter 

Low-Temperature Sediment-Hosted Copper Deposits 

Brown, AC 

2014 

Elsevier Inc. 

Treatise on Geochemistry 

13 

251-271 

English 

10.1016/b978-0-08-095975-7.01110-4 

Sediment-hosted copper mineralization is dominated by world-class stratiform deposits (sediment-hosted stratiform copper) located in carbonaceous marine or lacustrine graybeds (fine-grained clastic or carbonate units) overlying intracontinental rift redbeds. Copper was typically deposited as zoned fine-grained sulfide disseminations in the basal graybeds containing syndiagenetic pyrite or sour gas. Copper is widely accepted to have been leached from immature coarse-grained first-cycle clastic sediments of footwall redbeds (and possibly associated volcanic and basement rocks) during their progressive diagenetic alteration by low-temperature brines. At the basin scale, the circulating ore brine is interpreted to have been topography-driven meteoric water which was initially oxygen rich and became saline by assimilation of evaporitic salts. During its descent from rift-margin highlands into coarse-grained rift aquifers, the initially O2-rich brine lost oxygen by progressive hematitic alteration (reddening) of mafic minerals and simultaneously became a mildly oxidized, near-neutral pH solution capable of transporting copper as chloride complexes. Many geochemical and basin-scale aspects described earlier also apply to most closely related sediment-hosted copper deposit types (e.g., redbed-type and volcanic-associated redbed-type copper deposits). More distantly related deposit types (e.g., Mississippi Valley-type, sandstone uranium-vanadium, sandstone lead, and sediment-hosted iron oxide-gold-copper deposits) may also exhibit genetic similarities to SSC-type mineralization. © 2014 Elsevier Ltd. All rights reserved. 

Genesis; Geochemistry; Redbed copper; Sediment-hosted stratiform copper; Volcanic-associated redbed copper