Paleoproterozoic development of a gneiss dome corridor in the southern Lake Superior region, USA

Schneider, David; Holm, Daniel; O'Boyle, C.; Hamilton, M.; Jercinovic, M.J.

doi:10.1130/0-8137-2380-9.339

Cited by 25 publications

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“…1700 Ma mica dates from the McGrath Gneiss dome, mica and hornblende dates from plutons and country rock in the northern part of the plutonic zone are 1760-1750 Ma Holm et al, 1998a). A mean U-Pb meta-morphic monazite age of 1765 Ma was obtained on a garnet-staurolite schist sample also from the northern part of the plutonic zone (Holm et al, 2001a;Schneider et al, 2004). The Paleoproterozoic amphibolite facies metamorphism and gneiss domes (i.e., McGrath) in this region are features also characteristic of the deformed continental margin rocks north of the Niagara fault zone in northern Wisconsin and northern Michigan (Cannon and Ottke, 2000;Schneider et al, 2004).…”

Section: East-central Minnesota Plutonic Terranementioning

confidence: 99%

“…The steep, south-dipping Niagara fault zone is an 1860 Ma suture that separates the northern deformed continental margin rocks from the accreted Wisconsin magmatic terrane (Fig. 2;Schneider et al, 2004). The steep, south-dipping Eau Pleine shear zone in central Wisconsin separates the Wisconsin magmatic terrane rocks from the Archean Marshfi eld terrane to the south (Fig.…”

Section: -1400 Ma Geologic Settingmentioning

confidence: 99%

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U-Pb zircon geochronology of Paleoproterozoic plutons from the northern midcontinent, USA: Evidence for subduction flip and continued convergence after geon 18 Penokean orogenesis

Holm

Schmus

MacNeill

et al. 2005

Geol Soc America Bull

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We propose that the late Paleoproterozoic igneous and deformational history preserved in the northern midcontinent United States can be explained by a change in subductionpolarity from geon 18 south-dipping subduction during Penokean accretion to geon 17 north-dipping subduction as convergence continued after Penokean orogenesis. New U-Pb zircon ages indicate that late to post-Penokean magmatism occurred at ca. 1800, 1775, and 1750 Ma and generally migrated southeastward across the newly accreted Penokean terrane. We suggest that geon 17 Yavapai slab rollback caused continental arc magmatism to step southeastward between 1800 and 1750 Ma. As the slab steepened, reduced compressional stresses and magmainduced thermal weakening allowed for collapse of the overthickened portions of the Penokean crust. Postcollapse crustal stabilization (the 1750-1650 Ma Baraboo interval) was followed by geon 16 Mazatzal arc accretion further south. The 1900-1600 Ma tectonic history of the north-central United States, not surprisingly, records events related to the southward growth and tectonic development of the southern Laurentian margin.New and published 40 Ar/ 39 Ar mineral ages delineate the northern and western extent of geon 16 Mazatzal deformation. Interestingly, only little exhumed crust intruded by a small volume of shallow-level ca. 1750 Ma plutons (and associated rhyolites) was deformed signifi cantly during geon 16. In contrast, more deeply exhumed crust and crust pervasively invaded by a large volume of post-Penokean magma (i.e., East-Central Minnesota Batholith) were largely unaffected by Mazatzal deformation and reheating. We suggest that posttectonic intrusions and crustal thinning were an important step in strengthening and stabilizing the crust in the southern Lake Superior region.

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Section: East-central Minnesota Plutonic Terranementioning

confidence: 99%

Section: -1400 Ma Geologic Settingmentioning

confidence: 99%

U-Pb zircon geochronology of Paleoproterozoic plutons from the northern midcontinent, USA: Evidence for subduction flip and continued convergence after geon 18 Penokean orogenesis

Holm

Schmus

MacNeill

et al. 2005

Geol Soc America Bull

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“…An older minimum age can be inferred from the approximate age of metamorphism, which recrystallized the entire stratigraphic section at ca. 1830 Ma (Schneider et al, 2004;Holm et al, 2007). Because the Sudbury layer is succeeded stratigraphically by many kilometers of turbidites, all of which were deformed and metamorphosed by 1830 Ma, it is reasonable to infer that the Sudbury layer in Michigan was deposited well before the 1830 Ma metamorphism.…”

Section: Stratigraphy and Agementioning

confidence: 99%

The Sudbury impact layer in the Paleoproterozoic iron ranges of northern Michigan, USA

Cannon

Schulz

Horton

et al. 2009

Geological Society of America Bulletin

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A layer of breccia that contains fragments of impact ejecta has been found at 10 sites in the Paleoproterozoic iron ranges of northern Michigan, in the Lake Superior region of the United States. Radiometric age constraints from events predating and postdating depo si tion of the breccia are ca. 1875 Ma and 1830 Ma. The major bolide impact that occurred at 1850 Ma at Sudbury, Ontario, 500-700 km east of these sites, is the likely causative event. The Michigan sites described here, along with previously described sites in Minnesota and Ontario, defi ne an extensive ejecta-bearing deposit throughout the Paleoproterozoic iron ranges of the Lake Superior region that we refer to as the Sudbury impact layer. The layer at the sites in Michigan exhibits a range of thicknesses, lithologic characters, and sedimentary settings. The diversity of rock types and internal stratigraphic details of the layer imply that several different processes of transport and deposition are represented, but the detailed investigations needed to document them are incomplete. Many of the sites had been described and interpreted previously as products of common terrestrial processes, but the presence of relict shock-induced planar deformation features in quartz indicates that the breccia layer is in fact the product of an extra terrestrial impact. At most localities, this layer also contains relict fragments of altered devitrifi ed glass and/or accretionary lapilli. One immediate use of the impact layer is as an ultraprecise time line that ties together the well-known stratigraphic sequences of the various geographically separated iron ranges, the correlation of which has remained controversial for many decades. The Sudbury impact layer most commonly lies at a horizon that records a signifi cant change in the character of sediments across the region. The impact layer marks the end of a major period of banded iron formation deposition that was succeeded by deposition of fi ne clastic rocks, commonly black shales. The impact may have produced regional, if not global, changes in the environment that resulted in this widespread synchronous change in sedimentation style.

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“…Distal to the Republic Node, ores of the Tilden Mine have undergone greenschist facies metamorphism and are proximal to the chloritebiotite isograd (James 1955;Haase 1979). Schneider et al (2004) and Holm et al (2005) report metamorphic pulses at 1835, 1800, and 1770 Ma; however, this study does not attempt to differentiate the possible timing and associated effects of these overprints. Tilden Mine is located on the north side of the sheared contact between the Superior craton and the Archean basement, 25 km west of Marquette, and is the site of this study.…”

Section: Introductionmentioning

confidence: 78%

“…Shearing was accommodated by the crustal-scale Great Lakes Tectonic Zone. Anorogenic plutonism post-dates peak thermal Penokean metamorphism and subsequent development of the post-orogenic ϳ1750 Ma Republic Metamorphic Node thermally overprinted the Negaunee Iron Formation (James 1955;Schneider et al 2004;Tinkham and Marshak 2004;Schulz and Cannon 2007). Distal to the Republic Node, ores of the Tilden Mine have undergone greenschist facies metamorphism and are proximal to the chloritebiotite isograd (James 1955;Haase 1979).…”

Section: Introductionmentioning

confidence: 98%

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

Pietrzak-Renaud

2013

Can. J. Earth Sci.

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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 Cusulphides. 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.Résumé : La base de la Formation de fer Negaunee (Protérozoïque) affleure dans la mine Tilden, une fosse à ciel ouvert à Marquette, au Michigan. Juxtaposée au gneiss de Palmer (Archéen), elle est limitée par la zone de cisaillement Southern d'échelle régionale et par deux ensembles de dykes : un ensemble chloriteux et schisteux et un autre plus jeune datant du Keweenawan, 1,1 Ga. La mine Tilden est dominée par un anticlinal d'environ 100 m plongeant vers le nord-ouest et elle est recoupée par une faille synsédimentaire, appelée localement la faille de Tower Hill, qui coupe la zone de cisaillement Southern. La base de la formation de fer qui affleure comprend trois lithofaciès, incluant ...

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Paleoproterozoic development of a gneiss dome corridor in the southern Lake Superior region, USA

Cited by 25 publications

References 0 publications

U-Pb zircon geochronology of Paleoproterozoic plutons from the northern midcontinent, USA: Evidence for subduction flip and continued convergence after geon 18 Penokean orogenesis

U-Pb zircon geochronology of Paleoproterozoic plutons from the northern midcontinent, USA: Evidence for subduction flip and continued convergence after geon 18 Penokean orogenesis

The Sudbury impact layer in the Paleoproterozoic iron ranges of northern Michigan, USA

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

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