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GE0-3112 Sedimentary processes and products

Lecture 1. Depositional controls. GE0-3112 Sedimentary processes and products. 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.

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GE0-3112 Sedimentary processes and products

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  1. Lecture 1. Depositional controls GE0-3112 Sedimentary processes and products 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

  2. Depositional controls • Sediment supply • Accomodation space Corner, in press

  3. 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.

  4. 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)

  5. Sediment source (clastics) • Weathering

  6. Sediment source (clastics) • Weathering • Mass-wasting

  7. Sediment source (clastics) • Weathering • Mass-wasting • Erosion

  8. Sediment source (clastics) • Weathering • Mass-wasting • Erosion • Attrition

  9. Source area • Relief • High relief • Low relief

  10. Source area • Relief • Bedrock • Hard crystalline • Soft sedimentary

  11. Sediment delivery system • Glaciers • Mass-movement • Rivers • Wind • Waves • Tidal and ocean currents

  12. Accomodation space • Basin morphology • Base-level Corner, in press

  13. Basin morphology • Fjord example Corner, in press

  14. Basin morphology • Tectonic basin example

  15. Basin morphology • Shelf example

  16. Base level • Concept • Sea-level

  17. Sea level • Eustatic (global) sea level (eustasy) • Uplift/subsidence (isostasy) • Relative sea-level • Water depth Coe & Church, in Coe (ed.) 2003

  18. Transgression and regression Galloway & Hobday 1996

  19. Controls on deposition II • Independent variables • Extrinsic and intrinsic factors

  20. Controls on deposition II • Independent variables: • Climate • Tectonics Church & Coe, in Coe (ed.) 2003

  21. Climate

  22. Milankovitch

  23. Controls on deposition II • Independent variables • Extrinsic and intrinsic factors

  24. Depositional geometry • Progradation • Retrogradation • Aggradation Prothero & Schwab 1996

  25. 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.

  26. Hierarchy of depositional elements Strata Depositional unit Example Assemblages Lamina Bedform Ripple Facies Bed Bed/arch. element Bar Facies ass./ Member Architectural element Channel arch.element Formation Depositional basin Valley-fill Facies assoc. Group Basin/setting Foreland Miall, in Walker & James (eds.) 1992

  27. Hierarchy of depositional elements Miall, in Walker & James (eds.) 1992

  28. 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

  29. Facies Einsele 1992

  30. Facies and facies codes • Facies Miall, in Walker & James (eds.) 1992

  31. Facies successions Miall, in Walker & James (eds.) 1992

  32. Architectural elements Miall, in Walker & James (eds.) 1992

  33. Sequence stratigraphy Reading 1996

  34. Practical tips on sedimentological analysis • 1. Think process • 2. Think three-dimensional • 3. Think ’big picture’

  35. Tip 1. Think ’process’ • Example 1 –climbing-ripple bedding

  36. Tip 1. Think ’process’ • Example 2 – Fjord-valley fill stratigraphy Corner, in press

  37. Highstand systems tract Transgressive systems tract Forced-regressive systems tract Corner, in press

  38. Tip 2. Think ’3D’ • Example 1 – Trace fossils in section

  39. Tip 2. Think 3D • Example 2 – primary sedimentary structures

  40. Tip 2. Think 3D • Example 3 – Vertical (2D) sections Vorren & Mangerud, in press

  41. Tip 3. Think ’big picture’ • Spatial aspects of the system • Time aspects and system controls

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