Geochemistry and mineralogy of Neoproterozoic strata in northeastern Svalbard: reevaluating the prevalence of basalt weathering during the early Neoproterozoic

Journal article

Neoproterozoic strata of the Lomfjorden and lower Hinlopenstretet Supergroups (early−middle Tonian Veteranen Group, middle−late Tonian Akademikerbreen Group, and Cryogenian−Ediacaran Polarisbreen Group) in northeastern Svalbard, Norway, represent one of the most complete and well-preserved terminal Proterozoic sedimentary successions worldwide. These strata have been used in numerous geochemical compilations to probe Neoproterozoic paleoenvironments, including patterns of global chemical weathering prior to the snowball Earth events. Here, we present a new high-resolution geochemical data set incorporating δ¹³C, δ¹⁸O and ⁸⁷Sr/⁸⁶Sr data from carbonates with mineralogy, major- and trace-element data, and ε_Nd data from mudrocks to critically examine previously published data sets and better ally the succession with global Neoproterozoic records through a refined age model. We found that the geochemistry of Lomfjorden and lower Hinlopenstretet Supergroup mudrocks is greatly affected by carbonate contamination and that rigorous filtering is imperative for extracting reliable provenance and weathering information. Previous studies ascribed relatively juvenile detrital Nd isotope signatures in these units to a mafic detrital source region in support of the hypothesis that basalt weathering contributed to global cooling during the Tonian prior to the Sturtian snowball Earth event. In contrast, we present a new temporally extensive ε_Nd record that, when combined with elemental geochemical data, is best explained by the weathering of a combination of young and old granitic to granodioritic crustal sources, most likely sourced from the Grenville Province of Laurentia or Sveconorwegian Province of Scandinavia. Additionally, this new high-resolution mudrock data set allows us to assess paleoenvironmental and weathering trends within the Lomfjorden and lower Hinlopenstretet Supergroups, including the factors leading to exceptional fossil preservation in the ca. 790 Ma Algal Dolomite member of the Svanbergfjellet Formation, and post−snowball Earth weathering dynamics.

Authors: Millikin, AEG; Gibson, TM; Strauss, JV; Bergmann, KD; Tosca, NJ

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Geological Society of America
• Journal: GSA Bulletin
• Publication date: 2025-06-04
• Acceptance date: 2025-04-22
• DOI: 10.1130/b38195.1
• EISSN: 1943-2674
• ISSN: 0016-7606
• Language: English