SYNTHESIS OF THE LOWER HECLA HOEK SUCCESSION ACROSS EASTERN SVALBARD: EARLY TONIAN MAGMATISM AND BASIN FORMATION ALONG THE NORTHEASTERN MARGIN OF LAURENTIA

The Arctic archipelago of Svalbard, Norway, consists of three basement provinces juxtaposed by North-South-trending strike-slip fault zones. Here, we present new data and a revised synthesis of Tonian strata of the lower Hecla Hoek succession across the Eastern Basement Province of Svalbard to constrain the timing and tectonic setting of early Tonian magmatism and basin formation in the North Atlantic–Circum Arctic region. New high-precision U-Pb chemical abrasion isotope dilution thermal ionization mass spectrometry (CA-ID-TIMS) dates on zircon from felsic volcanic units of the Kapp Hansteen Group show that Tonian volcanism occurred as a single, short-lived ca. 960 Ma pulse rather than a protracted magmatic event. A new ca. 930 Ma Re-Os age from organic-rich sediment in the overlying Galtedalen Group in Nordaustlandet provides a key maximum depositional age for the lower Hecla Hoek succession and constrains the timespan represented by the Kapp Hansteen–Galtedalen nonconformity. In addition, new sedimentological, sequence stratigraphic, and detrital zircon U-Pb geochronological data from overlying strata of the Galtedalen, Franklinsundet, and Celsiusberget groups on Nordaustlandet also reveal clear correlations with the Veteranen Group of Ny Friesland, Spitsbergen. These data provide a coherent, basin-scale framework for the lower Hecla Hoek succession and its relationship with the underlying Kapp Hansteen Group across the Eastern Basement Province. Despite similarities between the Hecla Hoek succession and Eleonore Bay Supergroup in East Greenland, the revised dates on the Kapp Hansteen Group reveal that Tonian magmatism was asynchronous between these two regions. Together, these findings set the stage for understanding the tectonic setting responsible for widespread early Tonian basin formation and magmatism along the northeastern margin of Laurentia.