"FROM RUSSIA WITH LOVE”, OR THE SIBERIAN AND URALIAN ORIGINS OF MANY OF ALASKA'S ACCRETED TERRANES

Paleontological evidence from Paleozoic strata of many of Alaska's accreted terranes (notably the Farewell, Alexander, Livengood, White Mountains, York and Arctic Alaska terranes) show consistently strong affinities with Siberia and the Urals, rather than with Laurentia. This suggests that they represent rifted continental fragments of the Siberian paleocontinent (as postulated for the Farewell, Livengood, York and Arctic Alaska terranes) and associated nearby island arc complexes (as postulated for the Alexander terrane).

Time intervals reviewed here with particularly Siberian and/or Uralian affinities include the Middle Cambrian (trilobites from the Farewell and Arctic Alaska terranes), Early Ordovician (trilobites from the York terrane), Late Ordovician [pentameroid brachiopods (genera Tcherskidium, Eoconchidium, Holorhynchus, and n. gen. aff. Tcherskidium) and gastropods from the Farewell, Arctic Alaska, York, and White Mountains terranes], Late Silurian (brachiopods, gastropods, and sphinctozoan sponges from the Alexander and Farewell terranes), Early and Middle Devonian (brachiopods, gastropods, and calcareous algae from the Farewell, Alexander, Livengood, and Arctic Alaska terranes), and Late Mississippian brachiopods (notably gigantoproductids) and lycopods from the Arctic Alaska terrane.

Considerable work remains to better document Alaska's poorly studied Paleozoic fauna and flora, but paleobiogeographic evidence accumulated to date clearly demonstrate Siberian and Uralian ties, and not Laurentian! It is of note that similar close affinities are also shown between the Farewell and Alexander terranes of southern Alaska with the Yreka terrane of northern California, suggesting that the latter was also of similar derivation. Fossil faunas from Pennsylvanian/Permian strata of Alaska's accreted terranes are more poorly known than its older Paleozoic faunas, and comprise an especially enticing area for new studies. However, even the latest Paleozoic faunas likewise shown Eurasian, rather than Laurentian affinities.