Lecture 1: Scope, assessment and structure of course; Introduction to Sedimentology and Basic Definitions: uses and applications of Sedimentology.

Transcription

1 GEOL 440 Sedimentology and stratigraphy: processes, environments and deposits Jim Best MWF: Lectures and F: Laboratory Class Bruce Fouke Lecture 1: Scope, assessment and structure of course; Introduction to Sedimentology and Basic Definitions: uses and applications of Sedimentology.

2 The purpose of this course is to provide an integrated overview of the sciences of sedimentology and stratigraphy. State-of-the-art analytical tools will be integrated with the latest theoretical concepts on deposition and diagenesis to provide a comprehensive answer to the questions "What is the origin of a sedimentary rock?" and How can the study of sedimentary processes help us better understand ancient environments and manage modern environmental change. What is this course about? How do I get the most out of this course?

3 Course materials and textbooks Handout - course outline Handouts/lecture notes Other texts and journal papers essential

4 Course materials and textbooks Use Boggs for parts of course

5 Assessment Types Deadlines Curves

6 Questions? Any previous knowledge of sedimentology?

7 THE KEY - PROCESSES A general approach.. 1) Present is the key to the past (yes, but lets discuss!) 2) Observe the ancient 3) Do the inverse problem

8 techniques interregional mapping seismic imaging seismic imaging regional mapping well correlation local mapping outcrop/core studies facies analysis thin sections

9 Types of Sedimentary Rocks Siliciclastic conglomerates and breccias, sandstones and mudrocks Biogenic, biochemical & organic Chemical sediments Volcaniclastic limestones (& dolomites), cherts, phosphates & coals evaporites, ironstones ignimbrites, tuffs, debris flows

10 Some examples of sedimentary environments & rocks think about how we can best interpret the depositional environment from the rock record (i.e. what do we need to know as a sedimentary forensic scientist!)

11 Sedimentary environments: the framework weathering Source glacial erosion glacial runoff streams hillslope erosion landslides fluvial transport floodplains deltaic & estuarine trapping primary productivity shoreline Coral reefs open slopes fjords tidewater Sink shelf Stratigraphy shelf break abyssal plains or basin floor fans

12 Sedimentary environments Lets take a tour around some modern environments & their ancient equivalents. Source Sink

13 Deserts Algeria

14 Deserts The Namib Desert capped by basalt aeolian dunes

15 Rivers c.5 km Rakaia River, NZ

16 Rivers The joining of the Padma & Meghna Rivers, Bangladesh. c.3 km modern process ancient product

17 Rivers. and fans Rakaia River, NZ

18 Rivers some deposits Soft-sediment deformation Palaeo-Rakaia River deposit, Canterbury Plains, NZ Sandstone Bedforms Rudite/ conglomerate process environment geometry

19 Deltas (& deserts) 190 km The Nile Delta

20 Deltas Mississippi

21 Deltas process environment thickness variability porosity/perm structural control palaeoclimate 354 km The Ganges Delta

22 Deep Sea environments Delta front Shelf Canyons Mass movements Drift deposits Gravity flow deposits Storm deposits Offshore SE Indonesia Sinuous submarine channels

23 Salt lakes: Lake Eyre, Australia 20th December nd February 1984

24 Salt lakes 27th October th March 1985

25 Salt lakes deposits Evaporite

26 Carbonates Differences between clastics & carbonates In clastic sediments the grains & matrix are usually the result of disintegration of the parent rock, & transport into the depositional environment In carbonate environments, sediment is generally produced in-situ

27 Carbonates - reefs Brain corals Modern carbonate sediments are mainly composed of two minerals: calcite and aragonite.

28 Carbonates Carbonate formation may result in the following rock types: limestone, chalk, dolomite.

29 Volcaniclastic Mt. St. Helens Resultant deposits: pyroclastic flows debris flows/lahars ash beds

30 Volcaniclastic Mt. St. Helens

31 So what and where's this? Opportunity Mars Rover

32 OK but you are asking.why is Sedimentology important? so name a few? oil, gas and coal (source, reservoir and seal) detrital sediments - heavy metals (e.g gold), diamonds etc industrial minerals - sandstones, clays, aggregates modern environments - management & planning (e.g. groundwater) input to environmental engineering deciphering ancient climates and climate change

33 Reading for this time: B&D Chapter 1 Definitions, rationale or Boggs Introductory few pages (xviixix) and look at structure of B&D text (main chapter headings etc)

34 Next time: a very brief history of the subject and we ll begin to look at weathering and sediment production..