Tectonic assembly of east-central Alaska: Evidence from Cretaceous-Tertiary sandstones of the Kandik River terrane

East-central Alaska is a tectonically significant region between parautocht honons North America and the Arctic Alaska terrane to the north. The tecton ic evolution of the area is recorded in I,ate Jurassic to early Tertiary se dimentary rocks of the Kandik River terrane, Fine-grained elastic rocks dep osited in the area from Late Jurassic to Valanginian time represent a conti nuation of the passive margin sequence that persisted since the late Precam brian on the nearby North American margin, A pulse of quartz arenites (sand stones in the uppermost Glenn Shale and the Keenan Quartzite) reflects Vala nginian rift-shoulder uplift, marking initiation of crustal upwarping acid thinning that would later lead to the opening of the Canada basin, Fine-gra ined turbidites interpreted as distal submarine fan deposits (Biederman Arg illite), Valanginian to possibly as young as Aptian, were next deposited al ong the passive margin. These quartz wackes contain framework grains with t he same continental source as the quartz arenites, but geochemical evidence points to are detritus In the fine grained (pelagic) intervals. Compressio nal tec tonics began in the Aptian, and are recorded by are-derived volcani clastic turbidites (Kathul Graywacke) that were quickly overthrust, buried to depths of 5-8 l<m, then uplifted and eroded in the Late Cretaccous, Thes e events: record the accretion of a previously unreported island are to the porcupine and Kandik River terranes, followed by accretion of this complex to North America, A second orogenic event followed in the latest Cretaceou s to early Tertiary, when extension, possibly associated with emplacement o f Yukon-Tanana terrane along the Tintina fault to the south, produced a hal f graben (Nation River basin) and a pull-apart basin that were filled with litharenites derived from local sources (unit TKs). These deposits were bro adly uplifted and warped in the middle Tertiary, probably by regional Laram ide-age events. These results are significant in that they provide evidence for a previously unreported Aptian-Albian volcanic are in east-central Ala ska. In addition, comparison of sedimentation events in east-central Alaska with those recorded in the North Slope sequence;of northern Alaska provide s constraints On tectonic models for the evolution of northern Alaska.