Juha Köykkä - Oulu

Res Terrae, Ser. A 32, J. Köykkä, Sedimentology of the Mesoproterozoic Telemark basin-fills, South Norway: implications for
sedimentation processes, depositional environments and tectonic evolution
more rapid plate motions. The first sedimentation basin patterns at ca. 4.0–3.2 Ga were
probably a combination of intra-oceanic island-arcs, oceanic plateaus and plate tecton-
ic collision processes or more stable proto continents (Windley, 1995; Nijman and de
Vries, 2004). Although the early basin-fills were dominated by komatites and tholeites,
there is are also evidence of passive margin carbonates, banded-iron formations, stro-
matolites, evaporates, pelites and quartzites as well as synorogenic turbidites, conglo-
merates and sandstones (Windley, 1995). According to Eriksson et al. (2007), the Me-
soarchean sedimentary paleoenvironments were dominated by alluvial fans, braided
fluvial styles, shallow marine settings, turbidites, and tidalites associated with erratic
tectonism. According to Mueller and Corcoran (2001) and Eriksson et al. (2007), these
synorogenic volcanic-sedimentary greenstone successions exhibit subaerial and sub-
aqueous sedimentary rocks interbedded with volcanic material. The earliest evidence
of sedimentary recycling was found in South Africa (the Kaapvaal Craton) in a retro-
arc foreland basin (Catuneanu, 2001). During the Archean, sedimentary patterns were
commonly characterized by trangressive-regressive fluctuations in different sedimen-
tary environments, reflecting fining- and coarsening-upward sedimentation patterns in
proto-cratonic settings. The orogenic quiescence at 2.6–2.4 Ga is associated with glob-
al cratons, large epeiric basins, and passive margins (Windley, 1995). The earliest car-
bonate-banded-iron formation sequence, at 2.6–2.4 Ga, was probably linked to a eus-
tatic sea level rise. After Archean, tectonic stability led to more common rift and
strike-slip basins (Mueller and Corcoran, 1998), with syn-rift volcanic rocks followed
by alluvial fans and braided streams. Again, high-energy shallow marine sedimentation
was accompanied by intensive weathering.
In Paleoproterozoic to Mesoproterozoic time, the shallow marine nearshore envi-
ronments were sandstone dominated high-energy settings. In addition, sediment influx
and subsidence was probably more finely balanced than in Phanerozoic settings
(Eriksson et al., 1998). Overall, littoral barrier-island systems and lagoonal deposits
are rare in the Precambrian strata, possibly due to erosional effects by wave scouring
during transgression. The lack of stabilizing vegetation combined with rapid erosion,
intensive weathering, generally higher basin subsidence rates and steeper topographic
slopes during the Precambrian reflect wide and shallow shelves, thick and immature
delta sequences and lobes, and braid-dominated fluvial and tidal channels. Fluvial and
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