Petrography of the Sokoman Iron Formation in Part of the Central Labrador Trough, Quebec, Canada

Research Article| January 01, 1973 Petrography of the Sokoman Iron Formation in Part of the Central Labrador Trough, Quebec, Canada ERICH DIMROTH; ERICH DIMROTH 1Geological Exploration Service, Department of Natural Resources, Quebec, P.Q., Canada Search for other works by this author on: GSW Google Scholar JEAN-JACQUES CHAUVEL JEAN-JACQUES CHAUVEL 2Institut de Géologic, Université de Rennes, 35031 Rennes-Cedex, France Search for other works by this author on: GSW Google Scholar Author and Article Information ERICH DIMROTH 1Geological Exploration Service, Department of Natural Resources, Quebec, P.Q., Canada JEAN-JACQUES CHAUVEL 2Institut de Géologic, Université de Rennes, 35031 Rennes-Cedex, France Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1973) 84 (1): 111–134. https://doi.org/10.1130/0016-7606(1973)84<111:POTSIF>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 ERICH DIMROTH, JEAN-JACQUES CHAUVEL; Petrography of the Sokoman Iron Formation in Part of the Central Labrador Trough, Quebec, Canada. GSA Bulletin 1973;; 84 (1): 111–134. doi: https://doi.org/10.1130/0016-7606(1973)84<111:POTSIF>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 The sedimentary textures of the Sokoman Iron Formation are similar to those of limestones; therefore the classification of textural elements in limestone (Folk) can be applied to the iron formation. The authors recognized the following textural elements: (a) femicrite (a matrix of iron silicate and carbonate) and matrix chert, both analogous to micrite; (b) cement chert and carbonatic cements; (c) aggregated particles, comparable to Folk's allochems: pellets, intraclasts, oöliths, and pisolites. Shard textures are derived from oöliths and intraclasts by compaction. Rock types are defined by the combination of textural elements they contain.The iron formation suffered extensive epigenetic alteration. Dessiccation, shrinkage of silica-gel, compaction, and cementation are early diagenetic. Primocrystallization of quartz concludes the early diagenetic stage. It leads through a cryptocrystalline stage to the end phase of micropolygonal quartz. Quartz re-crystallized further during late diagenesis (burial metamorphism?) and again during a synkinematic to postkinematic regional metamorphism.Hematite dust is the oldest iron oxide. Much of the microscopic magnetite and specularite formed during early diagenesis. Migration of iron occurred; iron has been enriched in magnetite- or hematite-rich layers ("metallic" layers) during early diagenesis. Renewed crystallization of iron oxides occurred during the regional metamorphism.Microgranular siderite is perhaps primary. Porphyroblasts and glomero-porphyroblastic concretions of siderite, ankerite, and ferriferous calcite are early diagenetic. Minnesotaite and stilpnomelane are late diagenetic minerals. Riebeckite (and perhaps talc) formed during the regional metamorphism. 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.