Comparison of glacigenic strata in northeastern Svalbard and Northeast Greenland: implications for dynamic glaciation in the Cryogenian Period

Cryogenian glacial sediments (720 to 635 Ma) are widespread in the Arctic region. These sediments have been interpreted in terms of a Snowball Earth Model which postulates complete or near freezing of the Earth’s surface during the Sturtian (717-659 Ma) and Marinoan (645-635 Ma) episodes of panglaciation.

The Polarisbreen Group in the Svalbard archipelago records some of the best-exposed and best-preserved examples of Neoproterozoic glaciation in the world. Two distinct glacigenic units, assigned to the Sturtian and Marinoan glaciations, are recorded in the Petrovbreen Member of the Elbobreen Formation (15-20 m) and in the Wilsonbreen Formation (~160 m), respectively. Recent work on the latter has shown that these deposits are characterized by an interplay of glaciolacustrine, subglacial and non-glacial conditions during repeated advance and retreat cycles (Benn et al., Nature Geoscience, 2015 and Fleming et al., Sedimentology, 2016), possibly in response to orbital forcing.

In Northeast Greenland, the Sturtian and Marinoan glaciations are recorded in the Tillite Group by the Ulvesø and Storeelv formations, respectively. These units are similar both lithologically and isotopically to those in northeastern Svalbard and despite their present-day spatial disparity, are considered to have formed in a contiguous sedimentary basin (Fairchild & Hambrey, Precambrian Research 1995).

In this study, the facies, petrographic and provenance characteristics of the glacigenic units of the two regions are compared. The fluvial and lacustrine limestones that characterize the Marinoan of northeastern Svalbard are not present in Northeast Greenland. However, a range of glacial-depositional environments are recorded (glaciomarine, glaciolacustrine and subglacial) as well as non-glacial (terrestrial, and fluvial) environments that share many similarities with the Polarisbreen Group. These results show that the two areas share similar facies architectures and suggest that the Storeelv Formation also records repeated glacial advance and retreat cycles