Geologic and geographic analyses of Mono Basin and the surrounding area. Sachin Mehta Reno Nevada

1. Geological Investigation of
the Mono Basin and
surrounding area using
ArcGIS
Presented by Neil Pearson, Matt Durkee, Saching Mehta, Marvin James, Jeff
Lewis
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2. Three Main Tasks
Investigate the correlation of Faults and Springs
throughout the region
Chart the development of shorelines through time
Hyper spectral remote sensing of the Mono Craters
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3. General Geologic Setting and History
 The Mono Basin is the northwestern portion of
the Mina Deflection, a seismically active area
characterized by transtension.
 The transtension has led to the formation of the
basin and is partially responsible for the
volcanaic activity in Long Valley and the
Mono-Inyo Craters.
 The lake itself was formed ~700,000 years ago
when the Long Valley Caldera errupted and
cut off drainage to the Owens River Valley
 Since then the recorded highstand was during
the last glaciation 12,000 years ago, with lake
levels retreating since then
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4. Faults and Springs Analysis
Performed by Matt Durkee and Sachin Mehta
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5. Importance of Faults and Springs for
Identifying Potential Geothermal Sites
 Enhanced Geothermal Sites (EGS)
 Temperature > 200 ˚C Depth < 3Km
 Faults are the major controlling feature to fluid flow within a geothermal
region
 Multiple intermeshing, overlapping, and intersecting faults increase
permeability and flow
 Increased fracture density increases probability of geothermal activity
 Springs and wells are indicators of potential locations
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6. Importance of Faults and Springs for
Identifying Potential Geothermal Sites
 Current technology doesn’t allow for a high degree
of certainty of EGS without test drilling
 Drilling is very costly 1-3 million dollars
 Goal is to develop and analyze geothermal models
and systems to identify the most potential favorable
sites to find shallow hot rock spots and crustal stress
conditions with greater accuracy
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7. Synthesizing the Connection Between Close
Locality of Faults and Springs for EGS
Potential
 Trace and identify current and historical locations of theses faults and
springs utilizing different publications
 Using Arc Map perform combine feature class then generate near table to
assemble all the data together to perform near table operation
 Perform Both-Ends operation utilizing Arc Map to determine potential
concentration of active geothermal wells and springs through increased
hydrologic flow with increased fracture density
 Perform Dangle operation utilizing Arc Map to identify where separate
faults intersect, where there is a higher potential for increase hydrologic
conductivity and accumulation
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8. Synthesizing the Connection Between Close
Locality of Faults and Springs for EGS
Potential
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9. Synthesizing the Connection Between Close
Locality of Faults and Springs for EGS
Potential
 Goal is for future geothermal site exploration to increase utilization of past
and present fault and spring publications to be combined with GIS
programs that allow for statistical analysis on how far away springs are from
faults and how both-end and dangle can be applied to determine the EGS
of the underlying hot water reservoirs
 By determining the fault system and structural control we can determine
with greater accuracy thereby reducing the exploration costs
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10. Faults in the Mono Basin
 The Mono Basin was created by
warping of both tectonic plates
and faulting.
 The Basin holds various faults with
select types and areas that have
given rise to geothermal activity
in the basin.
 The present topography &
depressions/faults of the Mono
Basin has occurred throughout
the last three million years
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11. Mono Basin’s
Geothermal Features
• Locations of the various
thermal springs in and around
the Basin are controlled by
fractures (faults) and tufa
ridges.
• Mono Craters that are in the
region are steam explosion
volcanoes that have been
plugged by lava flow over the
past millennia.
• The majority of the 19 steam
vents (or fumaroles) intersect
with the faults of the Mono
region.
• We also identified
hydrothermal volcanic vents in
the area in order to assist in
possible exploration studies.
Fig. 1: Shows average distance of thermal spring to quaternary
volcanic vents in the Mono Basin Region
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12. Utilizing ArcGIS to Investigate
Geothermal Regions of Mono Basin
 Compile data from prior studies
and research and map this data
in ArcGIS.
 Fabricate various layers in order
to visually identify:
 Specific geologic points of
thermal springs, vents, etc.
 Inferred regions of these geologic
points.
 Specific depressions/faults &
inferred depressions/faults.
 Map the thermal springs from
across the basin and surrounding
regions in order to study any
spatial correlations between any
springs and faults lines.
 This will assist in identifying new
locations for geothermal
exploration.
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13. Mapped Geologic Points of Thermal Springs in
Long Valley using ArcGIS13

14. Start & End of Concealed Faults in the Mono Basin
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15. ArcGIS Analyses of Geothermal Regions in
Relationship to Faults in and around the Mono
Basin
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16. Lake Level Mapping
Performed by Marvin James and Jeff Roberts
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17. Lake Levels at Mono Lake
 Mono lake has a surface area of 69.5 square miles.
 It is hydrographically closed meaning that it only loses water to
evaporation.
 The lake level of Mono Lake fluctuates a lot.
 During glacial times the lake may have attained elevations of as much as
240 meters above its current elevation.
 Lake levels started to be officially recorded in 1911.
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18. Past Climate at Mono Lake
 Due to the recession of Mono
Lake, previously drowned
evidence of past lake fluctuations
have been made evident.
Stine, S. Past Climate at Mono Lake. Nature.
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19. Present Climate at Mono Lake
Stine, S. Geomorphic, geographic, and hydrographic basis for
resolving the Mono Lake controversy. Environmental Geology
and Water Sciences.
• Lake levels before 1940
remained fairly constant with a
little fluctuation.
• In 1941 L.A. County started
diverting water from Mono Lake
which caused a sharp decline in
the water level from 1940 to
1980.
• In 1994 L.A. County stopped
diverting water from Mono Lake.
• The water level is currently at
1944.4 meters.
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20. AVIRIS (Airborn Visible/Infrared Imaging
Spectrometer)
AVIRIS is a sensor developed by NASA and mainly
focused on understanding processes involving
global climate change.
Optical sensor that provides 224 spectral channels
(bands) with wavelengths from 400 to 2500
nanometers.
We were curious to see if using AVIRIS imagery
would help us see old shorelines of Mono Lake by
using different band combinations.
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21. Mapping of Shorelines
 Using AVIRIS imagery.
 Using different band
combinations we tried to see if
there were any visible signs of
shorelines.
 We used a decorrelation stretch
to enhance the image and make
shorelines easier to see.
 Using aerial imagery to detect
shorelines proved not to be useful
and did not provide us any
information.
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22. Decorrelation Stretch
 What is it?
 It can bring out elements of a
photo that were currently invisible
to the human eye.
 It improves visualization at difficult
sites.
 It removes the high correlation
often found in multispectral data
to produce very colorful
composite images.
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25. Hyperspectral Investigation of the
Mono Craters
Performed by Neil Pearson
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26. Background on Mono-Inyo Craters
 Approximately 40 Eruptions over
past 40,000 years
 Main Chain is silicic volcanics, i.e.
>70% silica
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27. Background on Hyperspectral imagery
 Used to determine mineralogy
and vegetation type (But who
cares about vegetation)
 Collected by the AVIRIS
instrument flown by the NASA ER-2
Plane
 ~15m resolution
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28. Decorrelation Stretch Image of the
Craters
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29. Spectra and the 2.21micron absorption
feature29

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31.  Work to be done includes a linear
regression of crater age with the
band depth derived from images
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32. Questions
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