Native copper occurs in a wide variety of environments that includes mafic lavas, hypabyssal diabasic intrusives, ultramafic intrusives, clastic sedimentary rocks, and the oxidized zone of sulfide deposits. Native copper is the predominant copper mineral in mafic lava flows, best exemplified in the Lake Superior region, and in some sedimentary rocks, but it is typically subordinate to sulfide copper in other types of deposits.Possible natural origins of native copper include: precipitation from sulfide-bearing hydrothermal solutions in rocks containing ferric oxide; deposition from sulfur-deficient magmatic or hydrothermal solutions; deposition from meteoric or hydrothermal chloride solutions in the presence of calcite, prehnite, or zeolites; precipitation from hydrothermal solutions by ferrous salts; organic precipitation from meteoric waters; reduction of copper sulfides by meteoric waters in the zone of oxidation; reduction of primary copper sulfides by later hydrothermal solutions.
Research Article| January 01, 1976 Geochronology of the Arabian Shield, western Saudi Arabia: K-Ar results ROBERT J. FLECK; ROBERT J. FLECK 1U.S. Geological Survey, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar R. G. COLEMAN; R. G. COLEMAN 1U.S. Geological Survey, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar H. R. CORNWALL; H. R. CORNWALL 1U.S. Geological Survey, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar W. R. GREENWOOD; W. R. GREENWOOD 2U.S. Geological Survey, Jeddah, Saudi Arabia Search for other works by this author on: GSW Google Scholar D. G. HADLEY; D. G. HADLEY 2U.S. Geological Survey, Jeddah, Saudi Arabia Search for other works by this author on: GSW Google Scholar D. L. SCHMIDT; D. L. SCHMIDT 2U.S. Geological Survey, Jeddah, Saudi Arabia Search for other works by this author on: GSW Google Scholar W. C. PRINZ; W. C. PRINZ 3U.S. Geological Survey, Washington, D.C. 20244 Search for other works by this author on: GSW Google Scholar J. C. RATTÉ J. C. RATTÉ 4U.S. Geological Survey, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar Author and Article Information ROBERT J. FLECK 1U.S. Geological Survey, Menlo Park, California 94025 R. G. COLEMAN 1U.S. Geological Survey, Menlo Park, California 94025 H. R. CORNWALL 1U.S. Geological Survey, Menlo Park, California 94025 W. R. GREENWOOD 2U.S. Geological Survey, Jeddah, Saudi Arabia D. G. HADLEY 2U.S. Geological Survey, Jeddah, Saudi Arabia D. L. SCHMIDT 2U.S. Geological Survey, Jeddah, Saudi Arabia W. C. PRINZ 3U.S. Geological Survey, Washington, D.C. 20244 J. C. RATTÉ 4U.S. Geological Survey, Denver, Colorado 80225 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1976) 87 (1): 9–21. https://doi.org/10.1130/0016-7606(1976)87<9:GOTASW>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation ROBERT J. FLECK, R. G. COLEMAN, H. R. CORNWALL, W. R. GREENWOOD, D. G. HADLEY, D. L. SCHMIDT, W. C. PRINZ, J. C. RATTÉ; Geochronology of the Arabian Shield, western Saudi Arabia: K-Ar results. GSA Bulletin 1976;; 87 (1): 9–21. doi: https://doi.org/10.1130/0016-7606(1976)87<9:GOTASW>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract An orogenic event, correlated with the Pan-African event in eastern Africa, affected the Arabian Peninsula between 510 and 610 m.y. ago and is well-recorded geochronologically. The event probably included two thermal pulses or maxima, the first occurring between 560 and 610 m.y. ago and the second between 510 and 540 m.y. ago. The earlier pulse, the more severe one, included the majority of the igneous activity and metamorphism. During the last part of the 510- to 610-m.y. period, left-lateral strike-slip faulting occurred along a set of northwest-trending en echelon fracture zones, whose composite displacement may be as large as 240 km. At least one and probably more orogenic events affected the Arabian Peninsula before the Pan-African event, but only minimum ages can be assigned to these, because thermal effects of the 510- to 610-m.y. event have reset K-Ar ages. Major diorite-granite batholiths, however, formed before 760 m.y. ago. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
Gibbsite, lithiophorite, pyrolusite, and goethite, plus discrete mixtures of gibbsite and lithiophorite and of gibbsite and iron oxide, occur as replacement veins in limestone. Minor accessories are barite, alunite, opal. Minerals of wall-rock alteration are garnet, idocrase, K-feldspar, prehnite, sericite, and quartz. These silicates formed at higher temperature than the vein minerals, but the whole sequence is considered to be a product of the same solutions, of deep-seated origin, deposited over a long period of time.
The 24 papers in this volume, written in honor of A.F. Buddington, cover a wide range of topics and geographic areas. H.H. Hesss History of Ocean Basins perhaps the most famous paper in the volume, introduces the concept of seafloor spreading.
The Greenstone flow, a thick, basaltic flow of the Keweenawan series of Michigan, offers a unique opportunity for the study of differentiation in basaltic magma. Differentiation trends in the magma of the Greenstone flow during crystallization have been computed according to two hypotheses as to the manner in which the flow solidified. It was found that the ratio of iron oxides to magnesia increased in the magma during crystallization and that there was a slight to moderate absolute enrichment of the magma in Fe, Ti, Mn, Cu, P, Si, Na, and K until the flow was nearly solid. A residual magma was produced that was rich in silica and alkalies and deficient in the remaining constituents. Magma trends in the lavas of the Keweenawan series and in genetically related intrusives have also been studied and compared with those found in the Greenstone flow.
