Docsity
Docsity

Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity


Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan


Guidelines and tips
Guidelines and tips

Geology Structure Blocks Diagram Analyses, Exercises of Geology

Part1 Knowing and Understanding Structural Terms and Symbols Part 2 Drawing and Interpreting Geologic Structures in Block Diagrams.

Typology: Exercises

2021/2022

Uploaded on 02/11/2022

michaelporter
michaelporter ๐Ÿ‡บ๐Ÿ‡ธ

4.4

(27)

287 documents

1 / 6

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
Student Name: Grade:_____
Physical Geology 101 Laboratory
Structural Geology II - Structure Block Diagram Analyses
Introduction & Purpose: Structural geology is the study of how geologic rock units are initially
arranged and later deformed. Changing spatial relations between geologic units and the stress and
strain that occur during deformation events are key aspects in understanding geologic structures. The
purpose of this lab is to both learn and apply the concepts of structural geology to reading and
interpreting geologic structures, including tilted beds, folds, and faults. The terms and concepts of
geologic structures, the application of structural geology to mountain building events, and the techniques
used to interpret geologic structures will be presented and discussed. The three types of graphic
representations of geologic structures: 1) geologic maps, 2) geologic cross sections, and 3) block
diagrams will also be highlighted and discussed.
Part I. Pre-Lab - Knowing and Understanding Structural Terms and Symbols:
A. Review of Rules for Interpreting Geologic Structures
There is a set of rules of structural geology used for interpreting geologic structures found in Figure
10.11 in your lab manual. Carefully study and make use of these rules for completing Part II. The
most important rules are listed below:
1) Strike of beds is always parallel to the direction of the contacts.
2) Rock layers dip towards the youngest exposed rock layers.
3) Oldest rocks exposed in the center of eroded anticlines and domes.
4) Youngest rocks exposed in the center of eroded synclines and basins.
5) Horizontal folds form parallel sets of belt-like outcrop patterns.
6) Plunging anticlines form โ€œVโ€ of "U" shaped, belt-like outcrop patterns.
๎˜ Anticline fold plunges toward closed end of โ€œVโ€ or โ€œUโ€ pattern.
7) Plunging synclines form โ€Vโ€ of โ€œU" shaped, belt-like outcrop patterns.
๎˜ Syncline fold plunges toward open end of โ€œUโ€ pattern.
8) Steeper the dip of the layer, the more narrow the width of its outcrop.
9) Hanging wall moves up relative to foot wall in reverse and thrust faults.
10) Hanging wall moves down relative to foot wall in normal faults.
11) Slickenside grooves that are oriented horizontal in fault scarp indicate strike-slip offset.
12) Slickenside grooves that are oriented vertical in fault scarp indicate dip-slip offset.
Part II - In-Lab: Drawing and Interpreting Geologic Structures in Block Diagrams
Introduction: Three-dimensional geologic block diagrams are scaled-down, abstract, simple
representations, or models of Earth's crustal rock structures, which include 1) formations, 2)
unconformities, 3) faults, 4) folds, and 5) topography. Block diagrams are a 3-dimensional composite
of both, a geologic map (horizontal map-view) and geologic cross-sections (vertical side-views). The
key to successfully completing the block diagrams lies in visualizing the 2-D representations as 3-D
structure.
pf3
pf4
pf5

Partial preview of the text

Download Geology Structure Blocks Diagram Analyses and more Exercises Geology in PDF only on Docsity!

Student Name: Grade:_____

Physical Geology 101 Laboratory

Structural Geology II - Structure Block Diagram Analyses

Introduction & Purpose: Structural geology is the study of how geologic rock units are initially arranged and later deformed. Changing spatial relations between geologic units and the stress and strain that occur during deformation events are key aspects in understanding geologic structures. The purpose of this lab is to both learn and apply the concepts of structural geology to reading and interpreting geologic structures, including tilted beds, folds, and faults. The terms and concepts of geologic structures, the application of structural geology to mountain building events, and the techniques used to interpret geologic structures will be presented and discussed. The three types of graphic representations of geologic structures: 1) geologic maps, 2) geologic cross sections, and 3) block diagrams will also be highlighted and discussed.

Part I. Pre-Lab - Knowing and Understanding Structural Terms and Symbols:

A. Review of Rules for Interpreting Geologic Structures There is a set of rules of structural geology used for interpreting geologic structures found in Figure 10.11 in your lab manual. Carefully study and make use of these rules for completing Part II. The most important rules are listed below:

  1. Strike of beds is always parallel to the direction of the contacts.

  2. Rock layers dip towards the youngest exposed rock layers.

  3. Oldest rocks exposed in the center of eroded anticlines and domes.

  4. Youngest rocks exposed in the center of eroded synclines and basins.

  5. Horizontal folds form parallel sets of belt-like outcrop patterns.

  6. Plunging anticlines form โ€œVโ€ of "U" shaped, belt-like outcrop patterns.  Anticline fold plunges toward closed end of โ€œVโ€ or โ€œUโ€ pattern.

  7. Plunging synclines form โ€Vโ€ of โ€œU" shaped, belt-like outcrop patterns.  Syncline fold plunges toward open end of โ€œUโ€ pattern.

  8. Steeper the dip of the layer, the more narrow the width of its outcrop.

  9. Hanging wall moves up relative to foot wall in reverse and thrust faults.

  10. Hanging wall moves down relative to foot wall in normal faults.

  11. Slickenside grooves that are oriented horizontal in fault scarp indicate strike-slip offset.

  12. Slickenside grooves that are oriented vertical in fault scarp indicate dip-slip offset.

Part II - In-Lab: Drawing and Interpreting Geologic Structures in Block Diagrams

Introduction: Three-dimensional geologic block diagrams are scaled-down, abstract, simple representations, or models of Earth's crustal rock structures, which include 1) formations, 2) unconformities, 3) faults, 4) folds, and 5) topography. Block diagrams are a 3-dimensional composite of both, a geologic map (horizontal map-view) and geologic cross-sections (vertical side-views). The key to successfully completing the block diagrams lies in visualizing the 2-D representations as 3-D structure.

A. STRIKE AND DIP BED AND BLOCK EXERCISES

  1. Measure the strike and dip of the two planar objects the instructor has set up in the class:

a) Planar Object #X - Strike = _______ Dip = _____

b) Planar Object #Z - Strike = _______ Dip = _____

  1. a) Complete the block (below) using the strike and dip shown on blockโ€™s top. b) Number all the beds. c) Estimate the dip amount and write it next to the strike and dip symbol. d) State the strike and dip in words here: ____________________
  2. a) Complete the block below using a 60 o^ dip amount. Note that the dip (tilt) direction must be determined from the age of the layers. b) Place a strike and dip symbol on the top of the block. Estimate the strike and dip of the beds. ____________________

B. FAULT BLOCK EXERCISES

  1. a) In map view (top of block), put strike and dip symbols on the beds and a fault dip symbol on fault. b) Also put appropriate displacement arrows on the fault in the frontal cross-section. What type of fault is shown below? ________________________.
  1. What type of fault is shown below if the slickensides are oriented horizontally? __________

Estimate the strike and dip of the fault: _____________ Estimate the dip of beds. _____

C. FOLD BLOCK EXERCISES

  1. a) Complete the block (below). b) Number the beds from oldest to youngest (1 being oldest). c) Indicate the axial plane and fold axis with appropriate symbols in both the map view and cross section. What is the name of this structure? ________________
  2. a) Complete the block diagram (below). b) Place strike and dip symbols on the map view (top of block) to indicate the structure. c) Label the axial planes and fold axes with the appropriate symbols. What is the name of this structure? ____________________________
  1. a) Complete the block (below). Dip amount is arbitrary, but dip direction is not. b) Number the beds from oldest to youngest (1 being oldest). c) Indicate the axial plane and fold axis with appropriate symbols in the map view and cross-section of the block. d) Place strike and dip symbols on top. What is the name of this structure?
  2. a) Complete the block (below). b) Number the beds from oldest to youngest (1 being oldest). c) Indicate axial plane and fold axis with appropriate symbols in the map view and cross-section. What is the dip angle? _____. What is the name of this structure? ___________
  3. a) Complete the block (below). b) Number the beds from oldest to youngest (1 being oldest). c) Indicate the axial plane and fold axis with appropriate symbols in the map view and cross- section face of the block. d) Draw strike and symbols on the map view. What is the fold plunge angle? _____. What is the name of this structure? ___________