THE DEVONIAN SUCCESSION IN NORTHERN NOVAYA ZEMLYA, ARCTIC RUSSIA: SEDIMENTOLOGY, PALAEOGEOGRAPHY AND HYDROCARBON OCCURRENCE

The Devonian succession was examined in two areas in northern Novaya Zemlya, one on the Barents Sea coast and one on the Kara Sea coast. On the Barents Sea coast, the Early Devonian succession comprises non-marine and near-shore marine siliciclastics which grade upward into shallow-marine platform carbonates. These facies are succeeded by Middle Devonian deeper-water mid-outer shelf black mudstones and shales. The Late Devonian succession consists of early Frasnian continental conglomerates and sandstones, and middle-Frasnian to Famennian shallow-marine platform carbonates. On the Kara Sea coast, the entire Devonian succession is dominated by shallow-marine carbonates, with deeper-water carbonate turbidites and shales in the late Lochkovian, marine siliciclastics in the Eifelian and non-marine sandstones in the early Frasnian. The Devonian palaeogeography of Novaya Zemlya is characterised by a deepwater slope-basin in the centre and east, and a shallow-marine carbonate platform in the south, west and north. Extensional tectonism influenced deposition of the Devonian succession, particularly during the late Givetian to early Frasnian. Solid bitumen is confined to carbonate facies and is most abundant in Early Devonian strata, occurring mainly within syn-tectonic fractures and associated secondary pore systems. In the mature Timan-Pechora Basin to the south of Novaya Zemlya, Devonian strata are an important element in the petroleum system; however, in the less-explored deep basins of the eastern Barents Shelf to the west of Novaya Zemlya, equivalent Palaeozoic strata are generally deeply buried beneath younger successions. Information from Novaya Zemlya therefore provides an important insight into the likely nature of successions and petroleum systems offshore.