Relationship between normalfaulting and drainage geomorphology

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Relationship between normal-faulting and drainage
geomorphology Josh Hackett
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Reason for the Study
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Outline

• Faulting and catchment size/location
• Faulting and drainage patterns (changes in
  lithology)
• Conclusions

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Normal Faults
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Faulting and Catchment Size Study Area
Central Nevada Seismic Belt

• East-West extension on North-South faults
• Underlain by basalt flows

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Faulting and Catchment Size
Footwall

• Hangingwall long, gentle slopes
• Footwall short, steep slopes

Hacks Law A 1.4L0.6 A is drainage basin
area L is slope length
Hangingwall
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Fault Segmentation and Catchment Location Study
Area

• Intermountain Seismic Belt
• Underlain by basalt flows

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Fault Segmentation and Catchment Location
Fault Offset
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Footwall Drainage Patterns

• Function of rock hardness
• Limestone (hard)
• Foliated Schist (soft)
• Neogene Sediments (softer)
• Examples from Greece
• North-South extension on
• East-West normal faults

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Drainage Patterns - Limestone
Rimnio-Servia Fault

• Form longitudinal patterns in
• the footwall
• Controlled by fault segmentation

• Footwall ridge remains
• undissected

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Drainage Patterns Foliated Schist
Rodia Fault

• Streams incise footwall
• Footwall becomes dissected
• Abrupt change from incision to
• deposition

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Drainage Patterns Neogene Sediments
Leontari Fault

• Long incised sub-parallel streams
• on footwall dip slope

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Drainage Patterns Comparisons

• Undissected footwall ridge
• Dissected footwall ridge
• flat irons
• Sub-parallel dip slope streams
• Lower gradient

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Conclusions

• The size of a catchment is determined by its
  structural position
• (footwall or hangingwall)
• Fault segmentation can provide opportunities for
  drainage growth
• Footwall lithology can influence drainage
  patterns
• Drainage size, location, and patterns may used to
  identify normal faults
• In areas of active extension