Arctic cretaceous tectonic and igneous mega-province (TIMP): Regional domains and geodynamics

Abstract

The Arctic Cretaceous Tectonic and Igneous Mega-Province (Arctic TIMP) was active in the period 125–80 Ma. We define a TIMP as a region that is large on a global scale and experiences widespread magmatism and tectonic extension. This province has three main domains: (1) the North Atlantic with its continental rifting, (2) the High Arctic Large Igneous Province (HALIP – the Arctic Ocean and some islands), and (3) part of the Verkhoyansk-Chukotka Orogen where collapse, extension and magmatism occurred. The classical HALIP regional domain has three main elements: (1) intraplate basalt plateau traps (flood basalts), (2) areas of intraplate intrusive magmatism (dykes and sills), and (3) the Alpha-Mendeleev LIP magnetic domain. Nine magmatic seismic facies for the Alpha-Mendeleev LIP magnetic domain are recognized, including SDRs, half-grabens with SDR-like units, layered horizontal volcanic flows and large volcanic constructions. New data support the hypothesis that below all the magmatic seismic facies lies continental crust stretched on different scales and intruded by basalts. Three possible stages of HALIP-age magmatism and tectonics are recognized: (1) formation of basalt trap-type plateaus (±125–120 Ma); (2) synrift and postrift magmatism with SDR units containing both tholeiitic and alkali basalts in the Alpha-Mendeleev region along with conjugate basins (±120–100 Ma); and (3) formation of a number of large, Fedotov-type volcanic constructions in the Alpha-Mendeleev region (±100–80 Ma). At about 120 Ma orogenic collapse started in Verkhoyansk-Chukotka Orogen. The collapse was accompanied by regional uplift and magmatism. Granitoid syn-extension magmatism occurred commonly throughout the area. A large part of the land was covered by volcanics with variable compositions. Rift valleys were common. Orogenic collapse ended at about 100 Ma. The general timing of the orogenic collapse, extension, and magmatism in the Verkhoyansk-Chukotka region coincides with magmatic and tectonic events in the HALIP. The Arctic TIMP formed as a single, connected geodynamic system.