NASA Astrobiology Institute (NAI)

1. Landforms made by groundwater discharge on Mars and Earth

   Project Investigators: Donald DePaolo, Michael Manga

   Other Project Members

   Sarah Aciego (Doctoral Student)

   William Dietrich (Project Investigator)

   Alan Howard (Collaborator)

   Taylor Perron (Doctoral Student)

   Joel Rowland (Doctoral Student)

   Jeremy Venditti (Collaborator)

   Peter Nelson (Doctoral Student)

   Dino Bellugi (Masters Student)

   Joel Scheingross (Research Staff)

   Eric Winchell (Undergraduate Student)

   Summary

   On Mars and Earth, deep canyons with steep walls and no tributaries are found to terminate upstream in sharp amphitheater-shaped heads. For decades researchers have interpreted such features as being created by springs draining deep groundwater which undermine the head and advance it forward, with important implications for the history of climate on Mars. We have found through extensive field study of these features on Earth that such canyons are formed by waterfall erosion rather than by groundwater seepage. Hence, this morphology on Mars does not reliably indicate sustained groundwater discharge. This requires reconsideration of the interpretation of these features and of their significance as indicators of Mars environmental history.

   Astrobiology Roadmap Objectives:

   • Objective 1.1: Models of formation and evolution of habitable planets

   Project Progress

   In 2007 – 2008 our most important discovery is that Box Canyon, Idaho, our Mars analog site for seepage erosion, was instead carved by a large paleoflood about 45 thousand years ago (Lamb et al., Science, 2008). This finding forces us to rethink the importance of groundwater and seepage erosion on Mars because many Martian canyons thought to be formed from seepage have the same morphologic traits as Box Canyon. It also has caused us to redirect our research to the mechanics of waterfall erosion in bedrock and to transport of coarse sediment in shallow flows. The paper received significant media attention. This work was complemented by supporting studies analyzing sediment transport physics (Lamb et al, JGR, 2008), Cosmogenic dating in Box Canyon (Aciego et al, 2007), and seepage erosion in Hawaii (Lamb et al, 2007). Our future efforts are too look in more detail at the physics of canyon erosion by large floods (Lamb et al, in prep).

   
   

   Fig. 1. (A) Shaded relief map of Box Canyon, Idaho. Airborne laser-swath mapping data were collected by the National Center for Airborne Laser Mapping. The data have been filtered to remove vegetation that exists along the creek banks. This is a Universal Transverse Mercator (UTM) zone 11 projection, North American Datum of 1983 (NAD83) datum, at 1 m resolution. (B) Thermal Emission Imaging System (32) infrared daytime image of Mamers Vallis, Mars, image V19470014, at 19 m resolution. (Lamb et al., 2008, Science)

   Mission Involvement

   Mars Science Laboratory

   Dietrich is part of the Malin/Edgett team for the MSL mission. The discoveries made with BioMars support have helped in discussions about landing site selection.

Publications

Aciego, S.M.  (2007).  Combining [3He] cosmogenic dating with U-Th/He eruption ages using olivine in basalt.  Earth and Planetary Science Letters, doi:10.1016/j.epsl.2006.11.039.

Lamb, M.P.  (2007).  Formation of amphitheater-headed valleys by waterfall erosion after large-scale slumping on Hawaii.  Geological Society of America Bulletin, 119:805-822.

Lamb, M.P.  (2008).  Formation of Box Canyon, Idaho, by megaflood: Implications for seepage erosion on Earth and Mars.  Science, 320(1067):doi: 10.1126/science.1156630.

Lamb, M.P.  (2008).  Is the critical Shields stress for incipient sediment motion dependent on channel-bed slope?.  Journal of Geophysical Research - Earth Surface, 113(doi:10.1029/2007JF000831).

Lamb, M.P.  (In preparation).  The persistence of waterfalls in fractured rock.  GSA Bulletin, In preparation.