Tillites, conglomerates and sandstones occurring in the basal part of the Smalfjord Formation along the Varangerfjord, East Finnmark, North Norway are believed to have formed during the retreat of a glacier.
At Kvalnes, on the south side of the fjord, the following sequence, up to 20 m thick, is found: (1) massive monomict tillite interpreted as a subglacial till, (2) massive polymict tillite with lenticular intercalations of stratified sandstone and tillite, interpreted as supraglacial/proglacial drift, (3) polymict conglomerate interstratified with laminated sandstones, interpreted as braided stream deposits. The last named interfingers laterally and is overlain by marine sandstones.
At Bigganjargga, near the head of the fjord, a lens of tillite about 3 m thick rests on a striated pavement and is overlain by sandstones and shales. Part of the tillite, containing irregular patches of slightly winnowed tillite, is interpreted as a melt‐out till, while a marginal part consisting of inclined tillite beds is interpreted as a series of flow till deposits. The lens is believed to be an oblique section through what was originally an ice‐cored moraine ridge. During a subsequent transgression, the moraine was partially eroded, a lag conglomerate was formed, and overlying marine sediments were deposited.
Bedded flow tills formed in a supraglacial/proglacial environment may be preserved where the extent of current reworking is very low (such as an isolated end moraine). Stratified conglomerate and sandstone, intimately intercalated with tillite, is to be expected at a glacier margin where glacial meltwater is locally and occasionally abundant, and glacier ablation permits downslope flowage of mobilized supraglacial fluid till.
The Vestertana Group in East Finnmark, North Norway, contains two Neoproterozoic glaciogenic sequences, the Smalfjord and Mortensnes formations, preserved on the northern edge of Baltica. The former comprises up to 420 m of aeolian, fluvioglacial and glaciomarine sediments and terrestrial diamictite. The latter consists of up to 50 m of predominantly diamictite. The Smalfjord Formation (Fm.) is underlain by dolostones (Grasdalen Fm., Tanafjorden Group), only locally preserved due to the sub-Smalfjord Fm. unconformity, which cuts down-section through a c. 2.5 km dominantly clastic sequence to rest on Baltic Shield gneisses. The two glaciogenic successions are separated by c. 350 m of mostly clastic sediments (Nyborg Fm.), with thin dolostones at the base and towards the top. The latter are generally absent due to the sub-Mortensnes Fm. unconformity, which also cuts down southwards through the Nyborg and Smalfjord formations to the Baltic Shield. No robust isotopic age constraints are available for the succession. d 13 C data, together with cap dolostone characteristics, offer paradigmic correlations with other areas (Smalfjord ; Marinoan; Mortensnes ; Gaskiers). A limited Ediacaran fauna, including Aspidella, give only broad age constraints. Palaeomagnetic data are ambiguous; some suggest Baltica lay at equatorial (158S) to mid-latitudes (508S) for the period 750-550 Ma, respectively, while other interpretations place it at either 308N or S at c. 550 Ma.
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