The Proceedings of the Eighth International Conference on Creationism (2018)

Archean, Paleoproterozoic, Mesoproterozoic and Neoproterozoic not as deep-time “Eons” or “Eras” but as mappable stratigraphic units having characteristic features. Relevant Bible verses, mapped regional stratigraphy and radiometric dates provided key data for the proposed time sequence model. REGIONAL GEOLOGY 1. Radiometric “age” dates and heating events Zircon is a commonly found as a trace constituent of most granitoid rocks. Zircons are resilient and contain high concentrations of important trace elements that include radiogenic isotope systems of geochronological importance, namely U-Pb and Th-Pb (Hawkesworth et al. 2010). A profound episodicity exists in the Precambrian geological record (O’Neill et al. 2013). Both igneous and detrital zircon populations show that major age peaks are global in extent (Condie and Aster 2010; Condie et al. 2017) (Fig. 2). The deformation age distribution of greenstone belts (most abundant at 2.70, 1.85, 1.05 and 0.60 Ga) is broadly similar to the age distribution of Precambrian granites and detrital zircons (Bradley 2011). Due to its hardness, durability and chemical inertness, zircon is a common constituent in detrital form in most sedimentary deposits (Fedo et al . 2003).  Detrital zircon grains can be used for sedimentary sequence provenance studies (Rainbird et al. 2012). On the basis of clusters of radiometric dates (U-Pb, K-Ar, Rb-Sr) which occur in well-defined areas (provinces), the three principal thermal-tectonic events in the Canadian Shield have been named the Kenoran, Hudsonian and Grenvillian (King 1976; Stockwell 1964) (Fig. 2). Reworking of earlier provinces (and overprinting of earlier events) is indicated on the Tectonic Map of North America (King 1976). Regional patterns of radiometric ages are correlatable with field relationships mapped on a province scale (Fig. 2). 2. Archean provinces geology The Earth’s radiometrically oldest continental crust is exposed in Archean cratons (Zientek and Orris 2005). Archean provinces display intense deformation over their entire area and show no stable areas at all. In contrast, for most terranes other than the Archean, crustal deformation is restricted to narrow belts (Frazier and Schwimmer 1987). Archean metamorphism is distinctively a low-pressure/high temperature variety (Anhaeusser 1975). North America’s Archean provinces include the Superior, Wyoming, Slave, Rae, Hearne, and Nain provinces (Fig. 1). The Superior Province is the world’s largest Archean province. These provinces essentially consist of high metamorphic grade granulite-gneiss terranes and low-grade granite-greenstone terranes. The Archean contains the oldest rocks, including the Acasta Gneiss Complex in the westernmost Slave Province (Iizuka et al. 2007). Only Archean megacrystic anorthosites have a highly calcic composition (Ashwal 2010). Sedimentary rocks and pillow lavas occur in greenstone belts such as the Isua greenstone belt of southwestern Greenland (Sharkov and Bogatikov 2010). Early Archean gneisses mainly consist of hydrous tonalite, trondhjemite and granodiorite (TTG) (Hamilton 2003). Greenstone belts are large and complexly-deformed belts which consist of thick and deeply infolded sequences of mainly mafic volcanics and associated sediments. Commonly granitic and gneissic rocks surround and locally intrude the greenstone belts. Greenstone belt sequences have been subjected to relatively low-grade metamorphism and contain komatiite (a high magnesium basalt) which has a high melting point, and which is characteristic of the Archean. Archean greenstone belts commonly contain banded iron formations (BIFs) and are called Algoma-type after a location in Canada. These deposits are mined in the Superior Province’s Abitibi greenstone belt and are rich in magnetite (Taner and Dickens ◀ North American Precambrian geology ▶ 2018 ICC 390 Figure 1. Generalized map showing NorthAmerica and Greenland’s major Precambrian provinces (with platform cover removed) and their principal rock types (after Mints, 2015). MR = Midcontinent Rift. B = approximate location of Belt-Purcell Basin. In this paper’s proposed model, it is inferred that Archean to Mesoproterozoic geology formed during early Creation Week, and specifically that the 1, 2, and 3 numbering in this figure’s legend respectively refers to provinces formation in Creation Days One, Two, and Three.