A Four Billion Year Journey Through the ”Geological Map of the Arctic” Geodatabase
Christopher Harrison and Marc R. St-Onge
Geological Survey of Canada, Ottawa, ON, Canada.
The relational geodatabase assembled to produce the latest Geological map of the Arctic (Geological Survey of Canada Map 2159A, 2011) provides systematic descriptions of more than 1200 map units that encompass all onshore and offshore areas down to 60 degrees North latitude. Database queries, augmented by recent literature, reveal aspects of Arctic paleogeography through four billion years of Earth history.
Remnants of Eoarchean and Paleoarchean crust form nuclei for Mesoarchean crustal blocks most notably in northern Baltica, southwest Greenland, western Baffin Island, and in northwest Canada. Accretion of new crust was widespread in the Neoarchean and, by 1.8 Ga, Archean stable blocks of Nuna including the Slave, Karelia, Murmansk, Rae, Hearne, North Atlantic and Superior cratons were fused together by the Taltson-Thelon, Inglefield, Lapland-Kola, Nagssugtoqidian and Svecofennian orogens and the Himalayan-scale Trans-Hudson orogen.
Subsequent events follow a repeated pattern of supercontinent disintegration and rebuilding involving new arrangements of component continental blocks. In the Arctic, these half cycles include: 1) the break-up of Nuna after 1.8 Ga; 2) assembly of Rodinia after 1.27 Ga, 3) Rodinia disintegration accomplished after emplacement of the Tzetzotene, Franklin, Thule and Sarek swarms (0.78 to 0.59 Ga) but prior to the Cambrian and; 4) assembly of Pangea involving re-accretion of Baltica to Laurentia to form the Caledonides in the Silurian and of Siberia to Euramerica to form the Urals-Taymyr orogen in the late Carboniferous to early Permian. The fifth tectonic half cycle has involved the dismemberment of Pangea, a process that started with emplacement of the Siberian LIP in the Early Triassic (251-249 Ma).
Complications are provided by microplate evolution within each of the major tectonic half cycles for which insights are provided by time slice views of the North American and Russian Pacific Cordillera onwards from the lower Paleozoic. Most notable is the opening of the North Atlantic and accretion of Wrangellia and Alexander terranes to western North America beginning in the Middle Jurassic; similarly the accretion of the Kolyma-Omolon composite terrane to the eastern margin of Siberia in the Late Jurassic. Likewise, the evolution of the Arctic Ocean basin relates to the scattering of microplates that were detached from circumarctic Pangea including Arctic Alaska, Chukotka and parts of the Arctic East Siberian shelf starting probably in the mid- Early Cretaceous, and of Lomonosov Ridge in the Paleogene. Paleogeography of the Arctic Cretaceous indicates contemporaneous formation of the Amerasian Basin and Okhotsk-Chukhotsk volcanic belt during emplacement of the mid-Cretaceous High Arctic LIP and subsequently, the opening of the Labrador Sea-Baffin Bay, North Atlantic and Eurasian basins following late Paleocene-early Eocene emplacement of the North Atlantic LIP.
AAPG Search and Discovery Article #90130©2011 3P Arctic, The Polar Petroleum Potential Conference & Exhibition, Halifax, Nova Scotia, Canada, 30 August-2 September, 2011.���������������������������������������������������