02_416M-Grain Parameters_handout

02_416M-Grain Parameters_handout - Grain Parameters Lecture...

Info iconThis preview shows pages 1–15. Sign up to view the full content.

View Full Document Right Arrow Icon
Grain Parameters Lecture Outline II.Sediment / Rock textural classification III.Grain shape IV.Grain roundness V.Textural maturity VI.Grain surface features VII.Sediment / rock fabric Reading Assignment: Boggs, Chapter 3 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Why Do Grain-Size Analysis? Sediment / rock description = communication Sediment / rock name = classification = communication Information on source area, transport, and depositional environment 2
Background image of page 2
How To Measure Grain Size 3
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Full range of weathering products in transport Sediment from physical weathering Sediment from chemical weathering Ions from chemical weathering Wentworth Scale addresses sediment Sediment ranges from clay to boulder Uses geometric scale because grain size ranges from <0.004 mm to m Establishes size-classes (cobble, sand, silt, etc.) Standard sieve sizes for silt to pebble Also uses a Phi Scale to make units of equal value Phi = -log2d 4 Grain Size: Udden-Wentworth Scale
Background image of page 4
5 Millimeters Microns Φ (Phi Scale) Wentworth Size Class Conglomerate (rounded clasts) Breccia (angular clasts) Sandstone Mudstone Lithification conversion of unconsolidated sediments into rock
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
6 Text Version – Note sieve mesh size Table 3.1, p. 53.
Background image of page 6
How To Display The Grain-Size Data Record weights Always plotted as Coarse to Fine Histogram Frequency Curve Cumulative Frequency Curve Semi-Log Plot 7
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
“Average” grain size Mode - most frequently occurring size class Median – 50% Mean – arithmetic average Sorting Skewness Kurtosis 8 Statistical Treatment of Grain-Size Data
Background image of page 8
9 “Average” Grain Size φ84 φ16
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Why Sample at 16 & 84%; 1 sd 1 sd 68% 2 sd 2 sd 90% 16 % 84% 5% 95% 10
Background image of page 10
Significance of Average Grain Size Source Area – What size did the grains start at? Weathering history? Transport History Grain size directly correlates to energy level Selective transport Proximal to Distal fining Depositional Environment Energy level Depositional process of sediment layers Segregation of grain populations on bedforms Bedload vs. suspended load 11
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
12 Sorting – How Uniform Is The Population?
Background image of page 12
13 Sorting in Real Sediment
Background image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
14 Visual Estimates of Sorting Fig 3.3, p. 58.
Background image of page 14
Image of page 15
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/08/2011 for the course GEO 416M taught by Professor Staff during the Fall '08 term at University of Texas at Austin.

Page1 / 38

02_416M-Grain Parameters_handout - Grain Parameters Lecture...

This preview shows document pages 1 - 15. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online