SEDIMENTOLOGY, STRATIGRAPHY AND AGE OF THE TONIAN VETERANEN GROUP, NORTHEASTERN SPITSBERGEN, SVALBARD

The Hecla Hoek Series of northeastern Svalbard is a thermally immature, ~7 km-thick Tonian–Ordovician sedimentary succession underlain by felsic igneous and metasedimentary rocks. The upper Tonian–Ediacaran (ca. 820–600 Ma) Akademikerbreen and Polarisbreen groups have yielded critical insights into Earth’s climate, environment, and biological evolution during the Neoproterozoic Era; however, the underlying lower–middle Tonian (ca. 950–820 Ma) Veteranen Group has garnered little attention despite its well-preserved microfossil populations and continuity with carbonate facies of the Akademikerbreen Group. Here, we present data from a nearly continuous ~4.4 km-thick stratigraphic section of the Veteranen Group from Faksevågen, Spitsbergen. Facies analysis, sequence stratigraphy, and carbonate carbon and oxygen chemostratigraphy from this remarkable exposure provides key paleoenvironmental context for this poorly studied succession. We also present new CA-ID-TIMS zircon U-Pb geochronology from felsic volcanic and intrusive rocks of the Kapp Hansteen Group, which nonconformably underlies strata that are equivalent to the basal Veteranen Group. Whereas previous geochronological data indicated that Kapp Hansteen magmatism was active over a span of ~15 million years (ca. 945–960 Ma), our data suggests these volcanics were erupted over a <1 Myr interval at ca. 958 Ma. These new, high-precision U-Pb ages constrain the onset of sedimentation in the Hecla Hoek basin and permit more accurate subsidence-age models for Neoproterozoic strata of northeastern Svalbard. Results from this study characterizing the sedimentology, stratigraphy and age of the Veteranen Group also set the stage for future geochemical and paleontological investigations of one of the most continuous Tonian sedimentary successions in the world.