LATE DEVONIAN SEDIMENT PROVENANCE OF THE ANDRÉE LAND BASIN, SVALBARD, NORWAY

Sediment provenance analysis and the paleogeographic reconstruction of the Svalbard archipelago during the Late Devonian is an important constituent in further understanding the tectonic processes that define the geologic setting of the modern Arctic. Following the initial collision between Laurentia and Baltica, the Andréeland-Dicksonland graben formed in what is now the Northwest Province of Svalbard. Recent provenance data, including detrital zircon U-Pb ages, have been collected from these units in the stratigraphically well-constrained Mimerdalen Section near Pyramiden, Spitsbergen.

The Andrée Land Group consists of strata from the Mimerdalen subgroup (Middle to Late Devonian), as well as the Wood Bay Formation (Early Devonian) and were primarily deposited in a fluvial and marginal-marine environment. Here we focus on the Late Devonian strata from the Mimerdalen subgroup. Samples were collected from the Frasnian Fiskekløfta Member of the Tordalen Formation, the early Famennian Planteryggen Formation, and the late Famennian Plantekløfta Formation. Detrital zircon ages from all units are predominantly Tonian to early Paleoproterozoic in age (ca. 900-2200 Ma). Samples from the Fiskekløfta Member of the Tordalen Formation contain a significant Caledonian (ca. 410-460 Ma) age group. The detrital zircon age groups are more diverse in the Planteryggen Formation with some samples containing abundant Caledonian ages while others display only a few Caledonian detrital zircon grains. The one sample from the Plantekløfta Formation has a minor amount of Caledonian and Timanian ages and appears similar to age spectra from the underlying Wood Bay Formation.

In the Middle and Upper Devonian strata, a distinct change in composition from the underlying strata marks the shift to a predominantly eastern provenance, supplied by the uplift of the Ny Friesland block of eastern Spitsbergen. All lithologic, paleocurrent, and detrital zircon data point to local sediment sources with little input from distal sources. These results reflect an increase in tectonic activity prior to and during the Svalbardian event and help to constrain the regional uplift and sediment provenance evolution of Spitsbergen in the late Devonian.