Download
1 / 31

Slide 1 - PowerPoint PPT Presentation


  • 83 Views
  • Uploaded on

Announcements Midterm Monday! Bring calculator, protractor, ruler, stereonet and tracing paper Talk This Thurs. 4 pm, Rm. Haury Bldg. Rm 216, "The role of orogen-parallel extension during the India-Asia collision", write 1 paragraph summary (+1% extra credit).

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Slide 1' - gyan


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

AnnouncementsMidterm Monday!Bring calculator, protractor, ruler, stereonet and tracing paperTalk This Thurs. 4 pm, Rm. Haury Bldg. Rm 216, "The role of orogen-parallel extension during the India-Asia collision", write 1 paragraph summary (+1% extra credit)


Brittle fault rocks and kinematic indicators(D&R: 280-286; 297-300)

1. Descriptive terminology2. Determining direction of slip3. Determine sense-of-shear


Breccias: fault rocks composed of angular fragments of wall rock set in a finer-grained matrix of crushed wall rock; classified based on clast size

megabreccia! (well, almost)



gouge: very fine-grained; clayey


cataclasite: very fine-grained strongly indurated fault rock (white in photo)

concept of fault zone


cataclasite: commonly forms "ledges"


pseudotachylite: dark, very fine-grained and generally glassy fault rock; thought to represent rapidly chilled rock melt, with melting of rock due to shear heating during an earthquake event- WOW!

the glassy surface is the "generation" surface and the black veins are "injection veins"


Determining kinematics from fault fabrics1st step: figure out direction of slip2nd step: figure out sense-of-shear- this requires looking at fabrics that are oriented perpendicular to slip direction


slickensides: polished shiny fault surfaces due to abrasive actionslickenlines/striations: scratches




onto sense-of-shear...

chatter marks: step-like features oriented perpendicular to striations


What is it?

top-to-the right

Crystal fiber lineations: produced by preferred directional growth of minerals during faulting in direction of movement



conjugate Riedel shears

R: synthetic Riedel shearR': antithetic Riedel shearP: synthetic shear, subordinate to R and R' or absent


What is it?

R'

R'

R

R

main fault

left lateral

Where are R and R' shears?What is the sense-of-shear?Explain why R' shears are associated with veins



A summary What is it?

breccia

cataclasite

Riedel shears

gash fractures: form perpendicular to s3

normal fault


Important terminology/concepts

Breccias

megabreccia

breccia

gouge

cataclasite

fault zone

pseudotachylite

slickensides

slickenlines/striations

grooves

chatter marks

crystal fiber lineations

drag folds

Riedel shears

gash fractures


ad