Major Rock Units And Deformation Events

1613 Words Aug 14th, 2015 7 Pages
Figure 1: (A) North America with the location of Figure B outlined by the black box. (B) Simplified map of the tectonostratigraphic terranes comprising the Superior Province with locations of mineral deposits. (C) Tectonostratigraphic terranes of Minnesota. The location of Figure 3a is denoted by the black box. Terrane boundaries are denoted by thick black lines and iron formation is shown by thin red lines.
Table 1: Major lithologic units of the Wabigoon subprovince in Canada that are on strike with the rocks in the study area. Modified from Davis et al. (1989), Fralick and Davis (1999), and Czek and Poulsen (2010).
Figure 2: Lithostratigraphc correlation of major rock units and deformation events in the Neoarchean terranes of Minnesota.
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Likely time correlative to the OI, a magnetic mafic sill (Oaks Intrusion sill; OIS) intruded and inflated the volcanic pile after or contemporaneously with the main deformation event (D2).
Table 2: Magnetic susceptibility of common igneous rocks used for interpretation and modeling. From Ford (2008) and Anderson et al. (2013).
Figure 4: Profiles of magnetic data on cross sections A-A’, B-B’, and C-C’. The location of these cross section lines is shown on Figure 3b and Figure 6. Location of massive sulfides (MS), the Lost Lake Intrusive Complex (LLIC), magnetic halos (MH) surrounding the LLIC, the Oaks Intrusion sill (OIS), and faults (FLT) are labeled on residual field magnetic data plots. Vertical and horizontal derivative techniques outline shallow, highly magnetic causative anomalies and rock boundaries. The residual field magnetic field data effectively identifies and separates high and low amplitude and high and low wavelength anomalies used for geological interpretation. Upward continuation of the residual magnetic field to 500 and 1000 meters separates deep and shallow magnetic sources and qualitatively shows the orientation of rock bodies at depth.
Figure 5: Regional scale faults overlain on aeromagnetic data upward continued to various heights: (A) RTP; (B) Upward continued to 1000 meters; (C) Upward continued to 3000 meters; (D) Upward continued to 6000 meters.
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