Stepover or Relay Ramp in Normal Fault Zones

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Stepover or Relay Ramp in Normal Fault Zones

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Stepover or Relay Ramp in Normal Fault Zones:
Stepover or relay ramps are a type of displacement transfer structure between overlapping normal fault segments. Multiple intersections between the overlapping fault strands results in increased fracture density that enhances hydrothermal fluid flow.
Other definitions:Wikipedia Reegle


Step-over or relay ramp between two overlapping normal fault segments with multiple minor faults providing hard linkage between two major faults. Illustration by James E. Faulds.[1]

Faulds uses this term as a structural control found in the Basin and Range province of the US.

Stepover or relay ramps between overlapping fault strands are one of the most favorable structural settings for geothermal activity. As of 2011, ~32% of the more than 200 document geothermal fields in the Basin & Range were associated with step-overs or relay ramps in normal fault zones. Increased fracture density generated by intersections between multiple overlapping fault strands results in enhanced permeability that facilitates hydrothermal fluid flow. According to Faulds et al. (2011):

"Step-overs in normal fault systems are more prevalent within the extensional terrane that characterizes much of the Great Basin northeast of the Walker Lane.”[1]

Examples

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CSV
Geothermal
Resource
Area
Geothermal
Region
Tectonic
Setting
Host
Rock
Age
Host
Rock
Lithology
Mean
Capacity
Mean
Reservoir
Temp
Desert Peak Geothermal Area Northwest Basin and Range Geothermal Region Extensional Tectonics Mesozoic greenstone 23 MW23,000 kW
23,000,000 W
23,000,000,000 mW
0.023 GW
2.3e-5 TW
481.15 K208 °C
406.4 °F
866.07 °R
Dixie Valley Geothermal Area Central Nevada Seismic Zone Geothermal Region Extensional Tectonics Jurassic Basalt 62 MW62,000 kW
62,000,000 W
62,000,000,000 mW
0.062 GW
6.2e-5 TW
504.15 K231 °C
447.8 °F
907.47 °R

References

  1. 1.0 1.1 James E. Faulds,Nicholas H. Hinz,Mark F. Coolbaugh,Patricia H. Cashman,Christopher Kratt,Gregory Dering,Joel Edwards,Brett Mayhew,Holly McLachlan. 2011. Assessment of Favorable Structural Settings of Geothermal Systems in the Great Basin, Western USA. In: Transactions. GRC Anual Meeting; 2011/10/23; San Diego, CA. Davis, CA: Geothermal Resources Council; p. 777–783