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Aerial photograph of Eagle-Picher Industries copper-shale strip mine at Creta in southwest Oklahoma. Highwall here is 13 m high.
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Many stratiform copper deposits are known in Permian shales and sandstones of Texas, Oklahoma, and Kansas, but the most important of these are six copper-shale ore bodies exposed in the Flowerpot Shale and San Angelo Sandstone along a total distance of some 200 km in Oklahoma and Texas. Individual ore bodies range from 15 to 45 cm thick and cover a...
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It is proposed that the Pinware orogen of eastern Canada, the Baraboo orogen of the midcontinent, and the Picuris orogen of the southwestern United States delin-eate a previously unrecognized, ~5000-km-long, ca. 1520-1340 Ma trans-Laurentian orogenic belt. All three orogenic provinces are characterized by Mesoproterozoic sedimentation, magmatism, m...
Citations
... Paleogeographic map of North America for the Guadalupian series (~260 Ma; Blakey, 2013) showing distribution of Permian red beds (red dashed line) and evaporites (blue dashed lines) and the provinces and ages of basement rocks supplying detrital zircons to strata in North America (red bed and evaporite outlines modified from Walker, 1967; provenance data from Dickinson and Gehrels, 2009). Johnson, 1974;Fay, 1975). Because sulfide minerals are unstable in oxidizing weathering environments, the cuprite likely formed as a product of recent weathering ( fig. 7). ...
Point of Rocks, a high-relief bluff overlooking the Cimarron River valley in Morton County, Kansas, is capped by distinct white beds of Neogene Ogallala Formation calcrete that overlie red beds of shale, siltstone, and sandstone. These unfossiliferous red beds are currently assigned to the Jurassic System; however, their age has long been debated due to a lack of marker beds, index fossils, and nearby correlative outcrops. As a result, geologists over the years have assigned the rocks to systems ranging from the Permian to the Cretaceous. In this study, four stratigraphic sections were measured in the red beds and three bulk samples were collected to determine the uranium-lead age distributions of detrital zircon (DZ) populations. Red-bed strata composed of fissile shale and sandstone are interpreted as alluvial overbank deposits, while dominantly trough cross-bedded and planar-laminated sandstones are interpreted as tidally influenced fluvial deposits. Detrital zircon age peaks can be grouped into at least seven subpopulations with a youngest single zircon age of 263.8 ± 12.1 Ma, a more conservative age of 293.0 ± 6.95 Ma based on the youngest grouping of three grain ages overlapping at 2σ, and a complete absence of Mesozoic age zircons. In addition, copper oxides along partings and fractures suggest that the red beds once hosted copper sulfides, a common constituent of regional Permian-Triassic red beds. The DZ data--in conjunction with the identification of the Permian Day Creek Dolomite marker bed in logs of nearby drilling tests--strongly suggest that the enigmatic red beds cropping out at the base of Point of Rocks should be assigned to the Guadalupian Big Basin Formation, the uppermost Permian unit in Kansas.
... STRATABOUND red-bed copper deposits are known to occur in southwestern Oklahoma (Hagni and Gann, 1976;Lockwood, 1976;Johnson, 1974) and northwestern Texas (Kidwell and Bower, 1976;Johnson, 1974). As part of a continuing effort by the Kansas Geological Survey to evaluate and assess the mineral potential of the state, sixteen holes were drilled during the summer of 1975 to evaluate the red-bed copper possibilities in Harper, Sedgwick, and Sumner counties in south central Kansas (Fig. 1). ...
... STRATABOUND red-bed copper deposits are known to occur in southwestern Oklahoma (Hagni and Gann, 1976;Lockwood, 1976;Johnson, 1974) and northwestern Texas (Kidwell and Bower, 1976;Johnson, 1974). As part of a continuing effort by the Kansas Geological Survey to evaluate and assess the mineral potential of the state, sixteen holes were drilled during the summer of 1975 to evaluate the red-bed copper possibilities in Harper, Sedgwick, and Sumner counties in south central Kansas (Fig. 1). ...
Subeconomic concentrations of copper sulfides within greenish gray shales, argillaceous dolomites, and limestones of the Lower
Permian red-bed sequence of south central Kansas have been investigated. The host rocks are similar to those hosting red-bed
mineralization in Oklahoma and Texas. Copper sulfides occur principally as replacements of earlier formed diagenetic pyrite.
Two distinct, spatially unrelated sulfide assemblages have been identified in drill cores. In the northern portion of the
area pyrite is replaced by chalcopyrite and then bornite at shallower depths. In the southern section pyrite is replaced by
"chalcocite" nearer the surface. The depth zonation strongly suggests that descending fluids produced the Cu mineralization.
Electron microprobe studies of the sulfide minerals indicate that bornite, as in other red-bed deposits, is sulfur rich. In
addition, true chalcocite (Cu 2 S) was not found in the studied area. Instead, two phases having compositions of Cu (sub 1.78 + or - 0.04) S (similar to
anilite) and Cu (sub 1.91 + or - 0.03) S (similar to djurleite) were identified. Thermochemical calculations suggest that
continuous depletion of a Cu-rich ore fluid and variations in pH and f (sub O 2 ) are responsible for producing the pyrite-chalcopyrite-bornite and pyrite-"chalcocite" assemblages.
White Pine, located in Michigan’s Upper Peninsula, is an archetypal sediment-hosted stratiform copper deposit. The Midcontinent rift system is one of only seven basins globally that host a giant sediment-hosted stratiform copper deposit. Despite many similarities with other deposits of this type, White Pine displays some important differences, including the late Mesoproterozoic age, a thick basalt sequence, an apparent lack of evaporites, and a lacustrine depositional setting. This study analyzes paleofluid flow related to the formation of White Pine and places a particular emphasis on structural and diagenetic fluid pathways.
Most of the ore is located in a 30-m-wide zone spanning the Copper Harbor Formation red beds and the overlying Nonesuch Formation shales. Sedimentation of these units was accompanied by subtle synsedimentary faulting. Premineralization phases include calcite concretions and nodules, illite and hematite grain coatings, isopachous chlorite rims, emplacement of liquid petroleum (now pyrobitumen), and bleaching. Mineralization introduced native copper into the footwall sandstones and a zoned suite of native copper and sulfur-poor copper sulfide minerals across a migrating redox front in the overlying shales where copper minerals nucleated on authigenic and detrital chlorite grains. Postmineralization phases include quartz cement, calcite cement, and calcite veins that partially overlapped inversion of synsedimentary faults. Contrary to previous studies, we identified evidence for only one phase of mineralization. An Re-Os chalcocite age of 1067 ± 11 Ma places mineralization 11 to 17 m.y. after host-rock deposition. Sulfide δ34S values of –14.0 to 29.9‰ suggest an important contribution from sour gas and thermochemical sulfate reduction of seawater. Carbon (δ13C) and oxygen (δ18O) isotope compositions of five calcite generations range from –15.1 to –1.3‰ and 10.4 to 41.3‰, respectively, and record early meteoric pore water displaced by later seawater.
White Pine is both a sediment-hosted stratiform copper deposit and a paleo-oil field. Synsedimentary faults controlled the sedimentological character of the upper Copper Harbor Formation, and together these imparted a strong control on fluid flow and later diagenetic processes. Early oxidized meteoric fluids were displaced by liquid petroleum and sour gas, which were in turn succeeded by metal-rich but sulfate-poor oxidized seawater. Burial compaction during deposition of the overlying Freda Formation drove fluids through White Pine due to its situation on a paleotopographic high near the basin margin. Mineralization occurred at ~125°C at depths of ~2.0 km and spanned incipient basin inversion related to the distal effects of Grenvillian orogenesis. The hightenor copper mineral assemblage is the product of an abundant supply of metal from basaltic volcanic detritus in the Copper Harbor Formation and low seawater sulfate concentrations in late Mesoproterozoic oceans. This demonstrates that viable sediment-hosted stratiform copper systems can form when a readily leachable metal source rock is present, even if hypersaline and sulfate-rich brines are not.
