Presentation on theme: "GE0-3112 Sedimentary processes and products Lecture 1. Depositional controls Geoff Corner Department of Geology University of Tromsø 2006 Literature: -"— Presentation transcript:
GE0-3112 Sedimentary processes and products Lecture 1. Depositional controls Geoff Corner Department of Geology University of Tromsø 2006 Literature: - Reading, 1996, Ch.2. Controls on the sedimentary rock record. - Leeder, 1999, ch. 1, 2, 13, 14, 15, 27, 28
Depositional controls ► Sediment supply ► Accomodation space Corner, in press
Sediment supply A) Terrigenous systems (allogenic, extrabasinal sediment source) – clastic sediments transported into the basin. B) Biochemical/chemical systems (autogenic, intrabasinal sediment source) – carbonate and other sediments produced in the basin.
Sediment supply ► Variations in: Volume and rate of delivery Grain size (calibre), etc. Petrographic composition (siliciclastic, carbonate) Mechanism of delivery (process) ► Determined by: Bedrock geology Tectonics/relief Climate Basinal water chemistry (for carbinates, etc.) ► (Denudation processes (weathering and erosion) and their intensity– dependent upon: relief Climate)
Facies models and depositonal systems ► Facies ► Facies succession (vertical succession; fining-upward, thickening-upward trends, etc.) ► Architectural element - medium- scale three-dimensional depositional body characterised by a distinctive assemblage of facies and geometry. ► Depositional system - three- dimensional assemblage of lithofacies genetically linked by active or inferred processes and environments.
Hierarchy of depositional elements StrataDepositional unit ExampleAssemblages LaminaBedform Ripple Facies BedBed/arch. element Bar Facies ass./ MemberArchitectural element Channel arch.element FormationDepositional basin Valley-fill Facies assoc. GroupBasin/setting Foreland Miall, in Walker & James (eds.) 1992
Hierarchy of depositional elements Miall, in Walker & James (eds.) 1992
Facies analysis ► Key to analysing deposits: meaningful identification of bounding surfaces, facies associations and/or architectural elements. ► Key to understanding deposits: interpretation of depositional elements with reference to depositional models Depositional model = process + bedforms/geometry + preserved deposits process + bedforms/geometry + preserved deposits