Contents - PowerPoint PPT Presentation

1 / 27
About This Presentation
Title:

Contents

Description:

Mineralogical (proportion of stable or resistant minerals) Pitfalls! ... Key physical and chemical characteristics of clay minerals ... – PowerPoint PPT presentation

Number of Views:35
Avg rating:3.0/5.0
Slides: 28
Provided by: TorbjrnT
Category:

less

Transcript and Presenter's Notes

Title: Contents


1
Contents
  • Introduction
  • Unconsolidated clastic sediments
  • Sedimentary rocks
  • Diagenesis
  • Sediment transport and deposition
  • Sedimentary structures
  • Facies and depositional environments
  • Glacial/eolian/lacustrine environments
  • Fluvial/deltaic/coastal environments
  • Shallow/deep marine environments
  • Stratigraphic principles
  • Sequence stratigraphy
  • Sedimentary basins
  • Models in sedimentary geology
  • Applied sedimentary geology
  • Reflection

2
Unconsolidated clastic sediments
  • Particles (or clasts) are the basic elements of
    any sediment
  • Clastic (terrigenous clastic or siliciclastic)
    sediments (80-85 of the stratigraphic record)
    consist of particles derived from pre-existing
    rocks, as opposed to non-clastic sediments
  • Texture
  • Grain (particle) size
  • Grain shape
  • Clast/matrix relationships
  • Fabric
  • Lithology is the general characterization of a
    sediment or a sedimentary rock (e.g., coarse
    sand, mudstone)

3
Unconsolidated clastic sediments
  • The Udden-Wentworth grain-size scale is based on
    factors of two ? -log2 (mm)
  • Mud (lt63 ?m gt4 ?)
  • Clay (lt4 ?m gt8 ?)
  • Silt (463 ?m 48 ?)
  • Sand (632000 ?m -14 ?)
  • Gravel (gt2000 ?m lt-1 ?)
  • Grain-size (particle-size, granulometric)
    analysis
  • The old-fashioned way direct measurement
    (gravel) and sieve/pipette analysis (sand and
    mud)
  • The modern technology laser particle sizing
    (sand and mud)

4
(No Transcript)
5
Unconsolidated clastic sediments
  • The Udden-Wentworth grain-size scale is based on
    factors of two ? -log2 (mm)
  • Mud (lt63 ?m gt4 ?)
  • Clay (lt4 ?m gt8 ?)
  • Silt (463 ?m 48 ?)
  • Sand (632000 ?m -14 ?)
  • Gravel (gt2000 ?m lt-1 ?)
  • Grain-size (particle-size, granulometric)
    analysis
  • The old-fashioned way direct measurement
    (gravel) and sieve/pipette analysis (sand and
    mud)
  • The modern technology laser particle sizing
    (sand and mud)

6
(No Transcript)
7
(No Transcript)
8
Unconsolidated clastic sediments
  • Moment measures
  • First moment mean (cf. median, mode)
  • Premier measure of the grain size
  • Second moment variance (cf. standard deviation)
  • Measure of the degree of sorting
  • (? standard deviation)
  • Third moment skewness
  • Measure of the symmetry of the grain-size
    distribution

9
(No Transcript)
10
(No Transcript)
11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15
Unconsolidated clastic sediments
  • Grain shape
  • Roundness (well rounded to very angular)
  • Sphericity (high or low)
  • Clast/matrix proportion
  • The matrix is the relatively fine-grained
    material that lies between the relatively
    coarse-grained clasts
  • Clast-supported sediments (clasts are in direct
    contact)
  • Matrix-supported sediments (clasts are entirely
    surrounded by matrix)
  • Fabric
  • Preferential orientation of particles in a
    sediment or tendency of a rock to break in
    specific directions

16
Unconsolidated clastic sediments
  • Sediment composition
  • Detrital mineral grains (quartz, feldspar, mica,
    heavy minerals)
  • Lithic fragments (polymineral grains or rock
    fragments)
  • Detrital mineral grains dominate in silts, lithic
    fragments dominate in gravels
  • Sediment maturity (degree of change compared to
    original bedrock provides evidence on the
    history of a sediment)
  • Textural (mud content, sorting, grain shape)
  • Mineralogical (proportion of stable or resistant
    minerals)
  • Pitfalls! (depends strongly on the nature of the
    original bedrock)

17
(No Transcript)
18
(No Transcript)
19
Unconsolidated clastic sediments
  • Sediment composition
  • Detrital mineral grains (quartz, feldspar, mica,
    heavy minerals)
  • Lithic fragments (polymineral grains or rock
    fragments)
  • Detrital mineral grains dominate in silts, lithic
    fragments dominate in gravels
  • Sediment maturity (degree of change compared to
    original bedrock provides evidence on the
    history of a sediment)
  • Textural (mud content, sorting, grain shape)
  • Mineralogical (proportion of stable or resistant
    minerals)
  • Pitfalls! (depends strongly on the nature of the
    original bedrock)

20
(No Transcript)
21
(No Transcript)
22
Unconsolidated clastic sediments
  • Clay minerals
  • Clay minerals are phyllosilicates with layered
    crystal structures
  • Kandite group (two layers) kaolinite
  • Smectite group (three layers) montmorillonite,
    illite, chlorite
  • Key physical and chemical characteristics of clay
    minerals
  • Platy shape (easy to keep in suspension, very
    slow settling rates)
  • Strong cohesion due to electrostatic charge
    (relatively difficult to erode, tendency to
    flocculate)

23
(No Transcript)
24
(No Transcript)
25
(No Transcript)
26
(No Transcript)
27
Unconsolidated clastic sediments
  • Clay minerals
  • Clay minerals are phyllosilicates with layered
    crystal structures
  • Kandite group (two layers) kaolinite
  • Smectite group (three layers) montmorillonite,
    illite, chlorite
  • Key physical and chemical characteristics of clay
    minerals
  • Platy shape (easy to keep in suspension, very
    slow settling rates)
  • Strong cohesion due to electrostatic charge
    (relatively difficult to erode, tendency to
    flocculate)
Write a Comment
User Comments (0)
About PowerShow.com