Probing the Precambrian Geodynamo: Analysis of the Geomagnetic Field Behavior and Calibration of Pseudo-Thellier Paleointensity Method for Mesoproterozoic Rocks

Foucher, M. S.

doi:10.37099/mtu.dc.etdr/657

Cited by 1 publication

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References 194 publications

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“…Mean paleomagnetic pole positions of all diabase sites, all anorthosite sites, as well as a grand mean pole developed by grouping the anorthosite and diabase sites into individual cooling units are plotted against a synthesized Laurentia apparent polar wander path (APWP) based on poles from Midcontinent Rift volcanics and sedimentary rocks (Swanson-Hysell et al, 2019). The paleomagnetic poles from the diabase and anorthosite are indistinguishable with the Greenstone Flow pole developed by Foucher (2018), but they all are distinct from the Portage Lake Volcanics mean pole (Swanson-Hysell et al, 2019). All directions shown are tilt-corrected.…”

Section: Table 1 Summary Of New Site-level Paleomagnetic Data For the Beaver River Diabase And Anorthosite Xenolithsmentioning

confidence: 99%

Synchronous Emplacement of the Anorthosite Xenolith‐Bearing Beaver River Diabase and One of the Largest Lava Flows on Earth

Zhang

Swanson‐Hysell

Schmitz

et al. 2021

Geochem Geophys Geosyst

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The North American Midcontinent Rift (MCR) is a ca. 1.1 Ga large igneous province for which there is excellent exposure of both the intrusive and extrusive components in the Lake Superior region (Figure 1). An exceptional feature within the MCR is the occurrence of large anorthosite xenoliths within a diabase sill and dike network known as the Beaver River diabase that outcrops in northeastern Minnesota, USA, as part of the Beaver Bay Complex (Figure 1). The anorthosite xenoliths range in size from centimeter-scale megacrysts to meter-scale, decimeter-scale and even  E 150-m-scale blocks (Figure 2; Grout & Schwartz, 1939;Morrison et al., 1983). A particularly large anorthosite xenolith is exposed at Carlton Peak in the eastern Beaver Bay Complex with minimum dimensions of 180  E 240 m (Figures 1 and 2; Boerboom et al., 2006). In the southern Beaver Bay Complex, a large anorthosite xenolith near Corundum Point has dimensions of 180  E 230 m while one exposed at Split Rock Point has dimensions of 180  E 260 m (Boerboom , 2004). To be able to accommodate such large xenoliths during magma ascent, the Beaver River diabase conduits must have been of at least the width of the anorthosite short-axis diameters. Such wide conduits in these near-surface intrusions suggest high magma flux rates and make it likely that the magma extruded to the surface-feeding voluminous lava flows. Miller and Chandler (1997) emphasized the composite nature of the Beaver River diabase network and Silver Bay intrusions (Figure 1), which are locally marked by abrupt transitions to progressively more evolved lithologies. Furthermore, Miller and Chandler (1997) documented geochronologic, geochemical, and structural evidence to support the notion that the diabase network may have served as principal feeder conduits to lava flows including parts of the Portage Lake Volcanics (PLV) on the Keweenaw Peninsula and Isle Royale of Michigan (Figure 1). To more directly test this inferred intrusive-extrusive correlation, Doyle (2016) compared the mineralogical, textural, and geochemical attributes and the composite lithologic nature of the Beaver River diabase against those of the Greenstone Flow, the largest lava flow within the MCR and one of the largest lava flows on Earth (Figure 3). Doyle (2016) documented remarkable similarities in petrography, mineral chemistry, whole rock geochemistry, and interpreted lithologic zonation between the Beaver River

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Section: Table 1 Summary Of New Site-level Paleomagnetic Data For the Beaver River Diabase And Anorthosite Xenolithsmentioning

confidence: 99%

Synchronous Emplacement of the Anorthosite Xenolith‐Bearing Beaver River Diabase and One of the Largest Lava Flows on Earth

Zhang

Swanson‐Hysell

Schmitz

et al. 2021

Geochem Geophys Geosyst

View full text Add to dashboard Cite

show abstract

Probing the Precambrian Geodynamo: Analysis of the Geomagnetic Field Behavior and Calibration of Pseudo-Thellier Paleointensity Method for Mesoproterozoic Rocks

Cited by 1 publication

References 194 publications

Synchronous Emplacement of the Anorthosite Xenolith‐Bearing Beaver River Diabase and One of the Largest Lava Flows on Earth

Synchronous Emplacement of the Anorthosite Xenolith‐Bearing Beaver River Diabase and One of the Largest Lava Flows on Earth

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