Cima Volcanic Field

• 32 cinder cones and ~50 associated basaltic lava flows of age ranging from 0.016 to 7.6 Ma. • Flows sit on crystalline rock and gravels of the Cima pediment dome. • Flows are 0.1 to 1.7 km wide, 0.7 to 9.1 km long. They typically consist of alkali basalts with mantle-derived xenoliths. Two categories: o Elongate flows with low gradients (1.5°-3.5°) and surface relief (1-5 m, decreasing with age). Constructional forms typical of pahoehoe and aa flows: levees, pressure ridges, collapse depressions, rafted spines and lobate margins. o • Original, constructional flow surfaces are first subjected to aeolian deposition and mass wastingEquant, during (width which ≈rock length) proj ectionsflows with are higherbroken gradients off and deposited and surface in low relief. spots; attributed to arid periods. Soil developed on older flows; attributed to cooler and wetter periods. • Drainage development, stripping of pavement and mantles, and bedrock exposure during early Pleistocene and Pliocene. • Importance of surface roughness: aeolian deposition, mass wasting and development of cobble pavement attenuate roughness. Drainage development increases roughness.

Figure 1: Geologic map of Cima volcanic field from Arvidson et al. (1993).

Following page: Landstat 7 Enhanced Thematic Mapper images, acquired on May 16 2002. Sun Elevation 67°, azimuth 123° (ESE). Figure 2: Natural color, pansharpened (15 m resolution). Figure 3: Vegetation should appear as yellow.

Figure 4: Vents are particularly bright at longer IR wavelengths, older lava flows have a stronger near-IR component.

Figure 5: Vents and lava flows have hotter surfaces than nearby terrains.

Figure 6: Cima volcanic field and surrounding areas. Note how the older volcanic vents in the north can be distinguished for their strong mid-IR signal. The associated lava flows can also be delineated due to their dark green borders.

Figure 7: Landsat 7 ETM band coverage. Bands 1-7 have 30 m resolution, except for band 6 with 60 m. The resolution of natural color and near-IR images can be improved to 15 m via sharpening algorithms using the panchromatic band.

The near-IR band is very sensitive to alive vegetation (Chlorophyll radiates at those wavelengths); while the two mid-IR bands are sensitive to particular mineral compositions, (e.g. Cima volcanic vents).

Figure 8: Topography power spectra of Cima lava flows with Figure 9: Simulated effect of different amounts of aeolian different ages. Note how power (a proxy for roughness) deposition on topography. Note how all wavelengths are decreases greatly with age between young and “mid-age” attenuated significantly with thicker deposits; a similar flows. This is interpreted as the effect of aeolian deposition and attenuation can be seen in the meansured topography spectra mass wasting. Then, roughness increases, especially at middle in Fig. 9. Image from Farr et al. (1992). wavelengths, possibly due to incision of drainage networks. Image and interpretations from Farr et al. (1992).

Figure 10: Interpreted modification of the landscape with age, from Wells et al. (1985). Although soil development is enhanced by the presence of vegetation (uniquely present on Earth), the other landscape-shaping processes involved in the modification of the Cima lava flows are active on other planetary bodies (e.g. Mars, Venus, Titan?). Figure 11: AIRSAR L-band (0.24 m) Horizontal polarization image of Cima volcanic field. The image is ~20 km across, radar illumination is from the southeast, incidence angles range from 21° in the lower right to 58° in the upper left. Note the stronger backscatter from the younger lava flows (a, lower left). Image from Arvidson et al. (1993).

Figure 12: Magellan radar image of Addams crater, Venus. The radar bright outflow associated with the 90 km crater stretches over 600 km to the east. The crater is located in the Aino Planitia region. Image and caption courtesy of Dave Williams, NASA Goddard Space Flight Center.

Figure 13:SAR view of Sedna Planitia. Contours are elevation in kilometers above the 6051 km radius reference. This image is about 2200 km wide. Image from Arvidson et al. (1992).

Figure 14:Geologic map of Sedna Lava Flows based on the SAR image above. Both radar backscatter characteristics and the law of superposition are used to delineate lava flow units and determine their relative age (see legend below). Image from Arvidson et al. (1992).

Lava tubes

• Formed during a lava flow, surface hardens and thermally insulates the lava flowing below. The latter can mechanically excavate the channel bed and induce melting of the inner surfaces of the tube, further increasing its size. Once the lava drains out of the tube, an empty cavity is left. • Human habitat (Mars): lava tubes can be excellent shelters against weather (wind, dust storms) and radiation. Daily and seasonal temperature excursions are mitigated due to thermal insulation. If water ever accumulated inside a lava tube, it may have been preserved thanks to shielding from incident solar radiation and cold trap mechanism. • Potential for life (Mars): Many species of any life kingdom spend part or all of their life cycles inside caves on Earth, including lava tubes. On Mars, favorable conditions to the development, survival and fossil preservation of any life form could have existed inside lava tubes for the same reasons explained above. • Need to explore and establish simple techniques and procedures to evaluate structural stability for safety purposes.

Figure 152: Collapse features in Hebrus Valles, Mars, imaged by the context camera (CTX) onboard Mars Reconnaissance Orbiter (MRO). Although these features are associated with drainage networks likely carved by water, their origin remains unclear. In fact, water could have flowed inside pre-existing lava tubes.

References: Arvidson, R.E., Greeley, R., Malin, M.C., Saunders, R.S., Izenberg, N., Plaut, J.J., Stofan, E.R., and Shepard, M.K., 1992, Surface modification of Venus as inferred from Magellan observations of plains: Journal of Geophysical Research: Planets, v. 97, no. E8, p. 13303–13317, doi: 10.1029/92JE01384. Arvidson, R.E., Shepard, M.K., Guinness, E.A., Petroy, S.B., Plaut, J.J., Evans, D.L., Farr, T.G., Greeley, R., Lancaster, N., and Gaddis, L.R., 1993, Characterization of lava-flow degradation in the Pisgah and Cima volcanic fields, California, using Landsat Thematic Mapper and AIRSAR data: Geological Society of America Bulletin, v. 105, no. 2, p. 175–188, doi: 10.1130/0016- 7606(1993)105<0175:COLFDI>2.3.CO;2. Farr, T.G., 1992, Microtopographic evolution of lava flows at Cima Volcanic Field, Mojave Desert, California: Journal of Geophysical Research: Solid Earth, v. 97, no. B11, p. 15171–15179, doi: 10.1029/92JB01592. Wells, S.G., Dohrenwend, J.C., McFADDEN, L.D., Turrin, B.D., and Mahrer, K.D., 1985, Late Cenozoic landscape evolution on lava flow surfaces of the Cima volcanic field, Mojave Desert, California: Geological Society of America Bulletin, v. 96, no. 12, p. 1518–1529, doi: 10.1130/0016- 7606(1985)96<1518:LCLEOL>2.0.CO;2.