Post by Dr. W. Brent Garry1, Dr. Jacob E. Bleacher2, Dr. James R. Zimbelman3, and Dr. Larry S. Crumpler4
- Planetary Science Institute, Tucson, AZ, 85719, USA
- Planetary Geodynamics Laboratory, Code 698, NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA
- Center for Earth and Planetary Studies, Smithsonian Institution, National Air and Space Museum, Washington, DC, 20013, USA
- New Mexico Museum of Natural History and Science, Albuquerque, NM, 87104, USA
In volcanology, we are traditionally taught about basaltic lava flows advancing as toes of pāhoehoe or as channeled ‘a‘ā flows. However, under the right emplacement conditions, some basaltic sheet flows will inflate (thicken) from only a few centimeters or meters to almost 20 meters in height. This process occurs when lateral advancement of the flow is inhibited and liquid lava is injected underneath the solid crust of stalled sections of the flow field, causing the crust to uplift over an expanding liquid core. The study of inflated lava flows on Earth reveals distinctive morphologic features related to this process including tumuli, inflated sheet lobes (Image 1), squeeze ups, and inflation-rise pits [1,2]. The McCartys lava flow (Image 2) is a 48-km-long, basaltic lava flow in El Malpais National Monument, near Grants, New Mexico that exhibits many of the complex morphologic features related to the process of lava flow inflation. By studying the morphologic features that are characteristic of inflated lava flows on Earth, we can begin to identify this style of lava flow on other planetary bodies, including the Moon and Mars [3,4,5].
For perspectives from the field, explore GigaPans of the McCartys lava flow to see the dramatic morphology of inflated lava flows.
- 360° Panoramic view of the McCartys lava flow from the field: http://www.gigapan.org/gigapans/74044/
- A view from on top of an inflated sheet lobe on the McCartys lava flow:
- A breakout of lava from an inflated sheet lobe on the McCartys lava flow: http://www.gigapan.org/gigapans/74336/
- Another view from the top of an inflated sheet lobe on the McCartys lava flow:
- Walker, G. P. L. (1991), Structure, and origin by injection of lava under surface crust, of tumuli, “lava rises”, “lava-rise pits”, and “lava-inflation clefts” in Hawaii, Bull. Volcanol., 53(7), 546-558.
- Hon, K., J. Kauahikaua, R. Denlinger, and K. Mackay (1994), Emplacement and inflation of pahoehoe sheet flows: Observations and measurements of active lava flows on Kilauea Volcano, Hawaii, Geological Society of America Bull., 106 (3), 351-370.
- Garry, W. B., J. R. Zimbelman, and J. E. Bleacher (2008), Morphology and emplacement processes at the distal end of the Carrizozo lava flow, New Mexico: Implications for Martian sheet flows, Lunar Planet. Sci., XXXIX, Abstract 1734.
- Zimbelman, J. R., W. B. Garry, J. E. Bleacher, and L. S. Crumpler (2011), Inflation features on the distal pahoehoe portion of the 1859 Mauna Loa flow, Hawaii: Implications for evaluating planetary lava flows, Lunar Planet. Sci., 42nd, Abstract 2443.
5. Garry, W. B., J. R. Zimbelman, J. E. Bleacher, S. E. Braden, L. S. Crumpler, and the LROC Team (2011), Lava flow inflation features on the Moon?: A comparison of Ina with terrestrial analogs, , Lunar Planet. Sci., 42nd, Abstract 2605.