Juha Köykkä - Oulu

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Res Terrae, Ser. A 32, J. <strong>Köykkä</strong>, Sedimentology of the Mesoproterozoic Telemark basin-fills, South Norway: implications for sedimentation processes, depositional environments and tectonic evolution 7 Conclusions 71 References 73 Original papers 89 10
Res Terrae, Ser. A 32, J. <strong>Köykkä</strong>, Sedimentology of the Mesoproterozoic Telemark basin-fills, South Norway: implications for sedimentation processes, depositional environments and tectonic evolution 1 Introduction Precambrian time encompasses approximately 88 % of Earth’s geological history between 4600 and 542 Ma. Clastic sedimentary deposits can be traced back to ca. 3.9 Ga, when the Earth was approximately 250 Ma years young (Wilde et al., 2001). These deposits provide fundamental information about the ancient atmospheric and environ- mental conditions (e.g., Altermann and Corcoran, 2002). Precambrian sedimentation basin is considered to be repository for the accumulation of succession of sedimentary and/or volcanic rocks, whose fill has a somewhat significant preserved surface area and total thickness (Eriksson et al., 2001). Tectonic regimes, which control the formation and evolution of sedimentary basins, were more erratic in terms of origin and rates during the Precambrian (Eriksson et al., 1998, 2004, 2005, 2007). The rates and inten- sities of processes in Precambrian sedimentary paleoenvironments differ significantly from the Phanerozoic ones, as a result of the lack of vegetation, faster rotation of Earth, faint young Sun, reduced albedo, abundant greenhouse gases, rapid micro- tectonism, dominant volcanism, and other biological and climatic differences (Eriks- son et al., 1998, 2004, 2005, 2007, 2009). By studying and understanding Precambrian geological processes and sedimentary paleoenvironments, is the key to comprehending present-day geological and ecological systems. Thus, the Precambrian past is the key to the present and to the true understanding of the Earth history and fundamental Earth processes (e.g., Altermann and Corcoran, 2002; Bose et al., 2010). Sedimentology and basin analysis understands sedimentary basins as geodynamical entities. It is a branch of geology that studies the composition, genesis, and depositional processes of sediments and sedimentary rocks deposited within sedimentary basins. Sedimentation basin is a product of isostatic compensation due to tectono-thermal processes operating at the lithosphere scale. However, from a sedimentological pers- pective, the formation of a sedimentation basin involves interplay between sediment supply and basin floor subsidence. Basin analysis interprets Earth’s geological history and reconstructs past sedimentary environments and the tectonic evolution of sedimentary basins by relying on the fundamental principles of uniformitarianism, actualism, and the law of superposition. These fundamental principles and ideas lead to specula- tions, hypotheses, theories and models of ancient sedimentary basins, including their sedimentary environments and sedimentation processes. 11
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Juha Köykkä - Oulu

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