lec.12 %kinema.cs
DESCRIPTION
Main%Topics%A%Defini.on%and%use%%B%Rela.ve%ages%%C%Displacements%vs.%rela.ve%displacements%TRANSCRIPT
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12. Kinema.cs
I Main Topics
A Defini.on and use B Rela.ve ages C Displacements vs. rela.ve displacements
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12. Kinema.cs How Did Points in Outcrop Move Through Time?
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1 Granodiorite
2 Dike 3 Dike
4 Joint
5 Fault
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12. Kinema.cs
II Defini.on and use of kinema.cs
A The study of the posi.on of bodies through .me without regard to the forces causing mo.on
B Used to describe how a body changes posi.on, orienta.on, shape,and/or size through .me
C Important for correctly assigning causes and effects
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12. Kinema.cs
III Rela.ve ages
A Cross-‐cuWng rela.onships 1 Younger features can cut older features; older features cannot cut younger ones
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12. Kinema.cs Cross-‐cuWng rela.onships
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hZp://marlimillerphoto.com/images/SrU-‐01.jpg
Angular unconformity, Siccar Point, Scotland
12. Kinema.cs Cross-‐cuWng rela.onships
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Nonconformity, Tapeats Sandstone overlying schist, Grand Canyon
hZp://marlimillerphoto.com/images/SrU-‐02.jpg
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12. Kinema.cs Cross-‐cuWng rela.onships
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Mafic dike cuWng aplite dike, Kings Canyon Na.onal Park, CA
12. Kinema.cs Cross-‐cuWng rela.onships
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Bio.te
Bio.te
From Paul Segall
Joint cuWng bio.te crystal
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12. Kinema.cs Cross-‐cuWng rela.onships
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Plutons
hZp://gsabulle.n.gsapubs.org/content/115/12/1570/F1.large.jpg
12. Kinema.cs Cross-‐cuWng rela.onships: “Pathologic” examples
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12. Kinema.cs Inclusions
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12. Kinema.cs
III Rela.ve ages
C Interac.on of structures
1 Older structures can affect the ini.al forma.on of younger structures, but younger structures cannot affect the origin of older structures
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12. Kinema.cs Interac.ng structures: T-‐shaped intersec.ons
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12. Kinema.cs Interac.ng structures: T-‐shaped intersec.ons
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12. Kinema.cs Interac.ng structures: Hook-‐shaped fractures
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From Pollard and Aydin, 1984
Curving, hook-‐shaped paths of interac.ng cracks at four different scales
12. Kinema.cs
IV Displacements vs. rela.ve displacements A Most of the displacements geologists measure are rela.ve displacements (GPS is sort of the excep.on)
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12. Kinema.cs
IV Displacements vs. rela.ve displacements B A lack of rela.ve displacement does not equate to a lack of absolute displacement (examples: joints and faults)
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12. Kinema.cs
IV Displacements vs. rela.ve displacements C Structural geologists usually cannot measure displacements rela.ve to an undeformed ini.al state; we only see the final deformed state
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12. Kinema.cs
IV Displacements vs. rela.ve displacements D Models influence what we measure, where we measure, and how we interpret our measurements 1 Faults and joints (see B)
2 Dependence on our concept of the ini.al state: is it deformed or undeformed?
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