Abstract

An immense wedge of Carboniferous to Jurassic siliciclastic strata accumulated on the Verkhoyansk passive margin of the Siberian craton. U-Pb ages of detrital zircons from Pennsylvanian to Middle Jurassic sandstones are remarkably consistent and show a systematic change in the proportion of age populations. Most zircons originated from the southern margin of Siberia, which was tectonically active in the Paleozoic and early Mesozoic, and were transported to the Verkhoyansk margin by a major transcontinental river system that existed for ~200 m.y., the paleo–Lena River. Specific sources are the Angara-Vitim batholith of Transbaikalia (315 and 291–288 Ma age peaks), plutons of the Altay-Sayan region of the Central Asia fold belt (494–482 Ma), Proterozoic granitoids of northern Transbaikalia and the East Sayan Range (1888–1832 Ma), and minor contributions from the Siberian Platform and Aldan Shield (2900–2300 Ma). The paleo–Lena River met its demise when the Verkhoy-ansk margin was deformed in the Late Jurassic and Cretaceous, and sediment was diverted north to the Arctic Ocean. Thus, the life span of major transcontinental drainage systems can be comparable to that of the plate boundaries that surround them.

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