1. 1. Geological Investigation of the Mono Basin and surrounding area using ArcGIS Presented by Neil Pearson, Matt Durkee, Saching Mehta, Marvin James, Jeff Lewis 1
2. 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 2
3. 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 3
4. 4. Faults and Springs Analysis Performed by Matt Durkee and Sachin Mehta 4
5. 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 5
6. 6. Importance of Faults and Springs for Identifying Potential Geothermal Sites Current technology doesnt 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 6
7. 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 7
8. 8. Synthesizing the Connection Between Close Locality of Faults and Springs for EGS Potential 8
9. 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 9
10. 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 10
11. 11. Mono Basins 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 11
12. 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. 12
13. 13. Mapped Geologic Points of Thermal Springs in Long Valley using ArcGIS13
14. 14. Start & End of Concealed Faults in the Mono Basin 14
15. 15. ArcGIS Analyses of Geothermal Regions in Relationship to Faults in and around the Mono Basin 15
16. 16. Lake Level Mapping Performed by Marvin James and Jeff Roberts 16
17. 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. 17
18. 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. 18
19. 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. 19
20. 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. 20
21. 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. 21
22. 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. 22
23. 23. 23
24. 24. 24
25. 25. Hyperspectral Investigation of the Mono Craters Performed by Neil Pearson 25
26. 26. Background on Mono-Inyo Craters Approximately 40 Eruptions over past 40,000 years Main Chain is silicic volcanics, i.e. >70% silica 26
27. 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 27
28. 28. Decorrelation Stretch Image of the Craters 28
29. 29. Spectra and the 2.21micron absorption feature29
30. 30. 30
31. 31. Work to be done includes a linear regression of crater age with the band depth derived from images 31
32. 32. Questions 32