Sedimentary and metamorphic lithofacies of the Lower Negaunee Iron Formation, Marquette District, Michigan, USA

The base of the Proterozoic Negaunee Iron Formation is exposed in the open pit at Tilden Mine, Marquette, Michigan. Juxtaposed against the Archean-aged Palmer Gneiss, it is bounded by the regional-scale Southern Shear Zone and cut by two sets of dykes: an older chloritic and schistose set and a younger 1.1 Ga Keweenawan set. Tilden Mine is dominated by a 100 m scale plunging northwest-anticline and is cut by a growth fault locally termed the Tower Hill Fault that intersects the Southern Shear Zone. The base of the exposed iron formation is composed of three lithofacies, including lower clastics that grade into the overlying banded iron formation that in turn grades upward into granular iron formation. This succession is capped by chloritic metadiabases locally termed the Summit Hill Sill and Pillar Intrusive. Petrographic and mineral chemical investigations document primary or early diagenetic hematite, siderite and possibly ferri-hydrite, metamorphic and related hydrothermal magnetite, chlorite, late martite overgrowing earlier magnetite and growth of specularite. All three lithofacies are cut by brittle fractures and late quartz veins. Brittle fractures are coated with chlorite, carbonate minerals, fluor-apatite, and sparse Cu-sulphides. These lithofacies document initial clastic sedimentation of strained detrital quartz into a subsiding fault trough. Over time, as subsidence slowed or sea level fluctuated, clastic deposition competed with quiescent chemical sedimentation, leading to deposition of the banded iron formation facies. As a stable shelf platform emerged, the granular iron formation facies was deposited via wave reworking of hardgrounds. Subsequent diagenesis initiated dissolution of carbonate and chert and promoted diagenetic replacement of primary iron minerals and chert. Regional metamorphism during Penokean orogeny at 1875–1835 Ma produced a suite of secondary metamorphic and related hydrothermal minerals. Metamorphism and hydrothermal flux related to the 1750 Ma development of the Republic Metamorphic Node overprinted the iron formation at Tilden to greenschist facies and infilled brittle fractures with a unique mineral assemblage. This unique mineral assemblage exhibits some striking similarities to Mn, Au, and Cu-sulphides documented at Champion Mine, west of Tilden, and proximal to the core of the Republic Node.

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Petro-Mineralogical and Geochemical Characterization of the Banded Irons Formations BIFs of the Nimba Range and its Western Extension (Nimba Region)

International Journal of Engineering Research in Africa ◽

10.4028/www.scientific.net/jera.44.99 ◽

2019 ◽

Vol 44 ◽

pp. 99-134

Author(s):

Mohamed Samuel Moriah Conté ◽

Abdellah Boushaba ◽

Ali Moukadiri

Keyword(s):

Regional Metamorphism ◽

Major Elements ◽

Iron Formation ◽

Banded Iron Formations ◽

Banded Iron Formation ◽

Metasedimentary Rocks ◽

Republic Of Guinea ◽

Metavolcanic Rocks ◽

The Republic ◽

Iron Formations

The Nimba Range and its western extension are located in the Nimba region on the borders of the Republic of Guinea, Liberia and Côte d'Ivoire. It is a mountainous region made up of metavolcanic and metasedimentary rocks. Metavolcanic rocks are gneisses, granites, amphibolites and quartzites, which constitute the lower part of Archean age. The upper part consists of Proterozoic rocks of metasedimentary origin. It contains important deposits of itabirites which occupy the top of the mountains and hills of the region. The petrographic study of the banded iron formations reveals the existence of silicate banded iron formations (SIF) and oxidized banded iron formations (OIF). The results of the scanning electron microscope (SEM) and metallogenic analyzes show the presence of iron minerals (magnetites, hematites, pyrites, goethites, martites and siderites). These analyzes also reveal the presence of the metamorphic index minerals associated with the banded iron formations, hence the existence of several types of ferriferous formations (silicate (SIF) and oxidized (OIF) banded iron formations). Overall, there is an increase in the degree of regional metamorphism from east to west of the Nimba region. The geochemical analysis of the banded iron formations reveals that with the exception of Na2O, all the major elements have a negative linear correlation although dispersed with Fe2O3. This correlation is explained by a decrease in quartz, garnet, micas (muscovite and biotite), amphibole, pyroxene, plagioclase, titanium and phosphorus contents. Conversely, there is an increase in iron ore content: magnetites, pyrites, hematites, goethite. But the alkali content remains constant in these banded iron formations. Then, the lower the Fe2O3content, the higher the FeO content, while those of SiO2and Al2O3are constant in all of these formations in the Nimba region except in the chlorite banded iron formation where both are anticorelated. Finally, the ratio SiO2/ Fe2O3vs MgO + CaO + MnO / Fe2O3of the banded iron formations of the Nimba region compared to the same formations of the whole world allows to give them Proterozoic age. Some itabirites have high levels of magnetite, hematite, and goethite (same feature as itabirites of Lac supérieur and Pic de fon) and only chlorite itabirite has a low to medium Mg-Si-BIF content.

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Essai de corrélation stratigraphique et structurale à l'est de Val-d'Or: implication pour la prospection aurifère du secteur

Canadian Journal of Earth Sciences ◽

10.1139/e87-227 ◽

1987 ◽

Vol 24 (12) ◽

pp. 2412-2421 ◽

Cited By ~ 1

Author(s):

Robert Marquis ◽

Normand Goulet

Keyword(s):

Regional Scale ◽

Shear Zones ◽

Iron Formation ◽

Banded Iron Formation ◽

Gold Exploration ◽

Third Phase ◽

Structural Relationships ◽

Regional Tectonic ◽

Ubiquitous Presence ◽

East West

Stratigraphic and structural relationships show that the Trivio and Garden Island sedimentary groups could be lateral equivalents. The ubiquitous presence of shear zones between the sedimentary (Trivio and Garden Island) and volcanic (Kinojévis and Malartic) groups indicates that these contacts are tectonic and not stratigraphic. Moreover, the shearing along the Malartic–Trivio contact is located along the extension of the Larder Lake – Cadillac fault zone and could be its equivalent east of Val-d'Or, Quebec.Three major periods of deformation have been recognized in the field. The main east–west deformation, D2, has produced isoclinal folds inclined to the southwest and plunging 60° to the northeast. The axial-plane schistosity associated with D2 is responsible for the regional tectonic grain. Its orientation, 290°/70°, closely parallels the shearing direction along the major volcanic–sedimentary contacts. At Chimo mine, on a mesoscopic scale, the isoclinal D2 folds refold D1 structures, producing interference patterns intermediate between types 2 and 3. On a regional scale the D1 folds do not affect the lithologic pattern.A late deformation, D3, becomes progressively more noticeable toward the Grenville Front. Folds related to this third phase are inclined toward the northwest and plunge to the northeast. The orientation of the fracture cleavage associated with this deformation is 040°/60°. The proximity of the Grenville Front, north of Lake Matchi-Manitou, is shown by strike faults oriented northeast–southwest. The sinistral movement of these faults was determined using a banded iron formation as marker horizon.All gold exploration criteria suggest that the study area is a favourable target for gold exploration.

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Earth’s Middle Ages: What Came after the GOE

10.23943/princeton/9780691145020.003.0009 ◽

2017 ◽

Author(s):

Donald Eugene Canfield

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Middle Ages ◽

Atmospheric Oxygen ◽

Iron Formation ◽

Banded Iron Formation ◽

Dissolved Iron ◽

Great Oxidation Event ◽

Low Levels ◽

Substantial Rise

This chapter considers the aftermath of the great oxidation event (GOE). It suggests that there was a substantial rise in oxygen defining the GOE, which may, in turn have led to the Lomagundi isotope excursion, which was associated with high rates of organic matter burial and perhaps even higher concentrations of oxygen. This excursion was soon followed by a crash in oxygen to very low levels and a return to banded iron formation deposition. When the massive amounts of organic carbon buried during the excursion were brought into the weathering environment, they would have represented a huge oxygen sink, drawing down levels of atmospheric oxygen. There appeared to be a veritable seesaw in oxygen concentrations, apparently triggered initially by the GOE. The GOE did not produce enough oxygen to oxygenate the oceans. Dissolved iron was removed from the oceans not by reaction with oxygen but rather by reaction with sulfide. Thus, the deep oceans remained anoxic and became rich in sulfide, instead of becoming well oxygenated.

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A new volcanic province: evidence from glacial erratics in western North Greenland

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/ggub.v186.5213 ◽

2000 ◽

pp. 35-41 ◽

Cited By ~ 1

Author(s):

Peter R. Dawes ◽

Bjørn Thomassen ◽

T.I. Hauge Andersson

Keyword(s):

Volcanic Rocks ◽

Iron Formation ◽

Banded Iron Formation ◽

Common Component ◽

Volcanic Province ◽

North West ◽

North East ◽

The North ◽

Surficial Deposits ◽

North Greenland

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Dawes, P. R., Thomassen, B., & Andersson, T. H. (2000). A new volcanic province: evidence from glacial erratics in western North Greenland. Geology of Greenland Survey Bulletin, 186, 35-41. https://doi.org/10.34194/ggub.v186.5213 _______________ Mapping and regional geological studies in northern Greenland were carried out during the project Kane Basin 1999 (see Dawes et al. 2000, this volume). During ore geological studies in Washington Land by one of us (B.T.), finds of erratics of banded iron formation (BIF) directed special attention to the till, glaciofluvial and fluvial sediments. This led to the discovery that in certain parts of Daugaard-Jensen Land and Washington Land volcanic rocks form a common component of the surficial deposits, with particularly colourful, red porphyries catching the eye. The presence of BIF is interesting but not altogether unexpected since BIF erratics have been reported from southern Hall Land just to the north-east (Kelly & Bennike 1992) and such rocks crop out in the Precambrian shield of North-West Greenland to the south (Fig. 1; Dawes 1991). On the other hand, the presence of volcanic erratics was unexpected and stimulated the work reported on here.

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3D Subsurface Characterization of Banded Iron Formation Mineralization using Large-Scale Gravity Data: A Case Study in Parts of Bharatpur, Dausa and Karauli Districts of Rajasthan, India

Natural Resources Research ◽

10.1007/s11053-021-09880-y ◽

2021 ◽

Author(s):

Saudamini Sahoo ◽

Anand Singh ◽

Santu Biswas ◽

S. P. Sharma

Keyword(s):

Large Scale ◽

Gravity Data ◽

Iron Formation ◽

Banded Iron Formation ◽

Subsurface Characterization

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Preparation and characterization of magnetic photocatalyst from the banded iron formation for effective photodegradation of methylene blue under UV and visible illumination

Journal of Environmental Chemical Engineering ◽

10.1016/j.jece.2021.105127 ◽

2021 ◽

Vol 9 (2) ◽

pp. 105127

Author(s):

Moustafa M.S. Sanad ◽

Mohsen M. Farahat ◽

Soliman I. El-Hout ◽

Said M. El-Sheikh

Keyword(s):

Methylene Blue ◽

Iron Formation ◽

Banded Iron Formation ◽

Magnetic Photocatalyst

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Serpentine–Hisingerite Solid Solution in Altered Ferroan Peridotite and Olivine Gabbro

Minerals ◽

10.3390/min9010047 ◽

2019 ◽

Vol 9 (1) ◽

pp. 47 ◽

Cited By ~ 3

Author(s):

Benjamin Tutolo ◽

Bernard Evans ◽

Scott Kuehner

Keyword(s):

Iron Formation ◽

Olivine Gabbro ◽

Banded Iron Formation ◽

Silicate System ◽

Duluth Complex ◽

Sheet Silicate ◽

Structure Modulation ◽

Compositional Variability ◽

Common Observation ◽

End Members

We present microanalyses of secondary phyllosilicates in altered ferroan metaperidotite, containing approximately equal amounts of end-members serpentine ((Mg,Fe2+)3Si2O5(OH)4) and hisingerite (□Fe3+2Si2O5(OH)4·nH2O). These analyses suggest that all intermediate compositions can exist stably, a proposal that was heretofore impossible because phyllosilicate with the compositions reported here have not been previously observed. In samples from the Duluth Complex (Minnesota, USA) containing igneous olivine Fa36–44, a continuous range in phyllosilicate compositions is associated with hydrothermal Mg extraction from the system and consequent relative enrichments in Fe2+, Fe3+ (hisingerite), Si, and Mn. Altered ferroan–olivine-bearing samples from the Laramie Complex (Wyoming, USA) show a compositional variability of secondary FeMg–phyllosilicate (e.g., Mg–hisingerite) that is discontinuous and likely the result of differing igneous olivine compositions and local equilibration during alteration. Together, these examples demonstrate that the products of serpentinization of ferroan peridotite include phyllosilicate with iron contents proportionally larger than the reactant olivine, in contrast to the common observation of Mg-enriched serpentine in “traditional” alpine and seafloor serpentinites. To augment and contextualize our analyses, we additionally compiled greenalite and hisingerite analyses from the literature. These data show that greenalite in metamorphosed banded iron formation contains progressively more octahedral-site vacancies (larger apfu of Si) in higher XFe samples, a consequence of both increased hisingerite substitution and structure modulation (sheet inversions). Some high-Si greenalite remains ferroan and seems to be a structural analogue of the highly modulated sheet silicate caryopilite. Using a thermodynamic model of hydrothermal alteration in the Fe–silicate system, we show that the formation of secondary hydrothermal olivine and serpentine–hisingerite solid solutions after primary olivine may be attributed to appropriate values of thermodynamic parameters such as elevated a S i O 2 ( a q ) and decreased a H 2 ( a q ) at low temperatures (~200 °C). Importantly, recent observations of Martian rocks have indicated that they are evolved magmatically like the ferroan peridotites analyzed here, which, in turn, suggests that the processes and phyllosilicate assemblages recorded here are more directly relevant to those occurring on Mars than are traditional terrestrial serpentinites.

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