Presentation is loading. Please wait.

Presentation is loading. Please wait.

Destabilization of Valles Marineris wallslopes by retreat of ancient glaciers Daniel MEGE Olivier BOURGEOIS Planetology and Geodynamics Laboratory CNRS.

Similar presentations


Presentation on theme: "Destabilization of Valles Marineris wallslopes by retreat of ancient glaciers Daniel MEGE Olivier BOURGEOIS Planetology and Geodynamics Laboratory CNRS."— Presentation transcript:

1 Destabilization of Valles Marineris wallslopes by retreat of ancient glaciers Daniel MEGE Olivier BOURGEOIS Planetology and Geodynamics Laboratory CNRS Research Unit #6112 University of Nantes, France

2 Valles Marineris wallslope morphogenesis Open air/fluvial? Submarine/lacustrine? Glacial/subglacial? Peulvast and Masson, 1993 1 2 3 Liquid flows? Viscous flows? Dry flows?

3 Doppelgraten (Penck, 1894; Paschinger, 1928) I U S C H A S M A G E R Y O N M O N T E S Ridge-top splitting double crest lines 1.Observations at intra-chasma and inter-chasma ridges, and terrestrial analogs

4 Ius Chasma ridge width 20 km Bodeneck, Austrian Alps ridge width 8 km glacial valley

5 C A N D O R C H A S M A M E L A S C H A S M A 1 km antislope scarps

6 Hoher Trog Oberes Törl Austroalpine nappes, Austrian Alps Thanks to Jürgen Reitner (Geol. Survey Austria) for this photograph!

7 Hoher Trog Thanks to Jürgen Reitner (Geol. Survey Austria) for this photograph! antislope scarps Austroalpine nappes, Austrian Alps M E L A S C H A S M A C A N D O R C H A S M A

8 Reitner and Linner, 2009 Jahn, Z. Geomorph., 1964 Historic study areas Tatra Mountains Tyrol Western Tatras Observation sites: Carpathians, Alps of Europe, Japan, and New Zealand; Cascades, U.S. and Canadian Rockies, Alaska, Andes, Scotland and England Caledonides, Himalaya Tatra Mountains (Slovakia and Poland) Nemčok, 1972; Kellog, 1984 Oberes Törl, Austrian Alps graben antislope scarps

9 Sackung (sagging) Deep-seated Gravitational Slope Deformation (DGSD) modern talented scientist jargon old-fashioned wording Deep-seated Gravitational Spreading (DSGS) Zischinsky, 1966

10 base map: Peulvast et al., 2001 (more) Valles Marineris ridge-top splitting and antislope scarp sites (more) inter-chasma ridge chasma wall intra-chasma ridge IUS MELAS

11 Deep-seated gravitational slope deformation antislope scarps basal bulging Hippolyte et al., 2006, 2009 Belledonne Range French Alps post-glacial slope deformation

12 SAGGING SLOPE (Geryon Montes) slope displacement 100 m horizontal dipping 11°S S A G G I N G S L O P E (Geryon Montes) no vertical exaggeration F O L D E D F L O O R vertical exaggeration x1.5 H O R I Z O N T A L F L O O R (LPSC 2005) Basal slope bulging in Ius Chasma

13 Deep-seated gravitational spreading in Ius Chasma 5 km basal bulge Mège et al., LPSC 2005 antislope scarps G E R Y O N M O N T E S

14 MELAS CHASMA More examples CANDOR CHASMA 10 km IUS CHASMA MELAS CHASMA CANDOR CHASMA 10 km MELAS CHASMA

15 CANDOR CHASMA OPHIR CHASMA 10 km More examples initial ridge top (split) 1 DSGS prior to ILD deposition! landslide 2 ILD 3 COPRATES CHASMA sturzstrom 10 km landslide DGSD initial ridge top steep landslide failure plane (56°) Lucas et al., LPSC 2009 + subm. JGR

16 Lucas et al., LPSC 2009 + subm. JGR s t e e p e n i n g i n i t i a l f a u l t s c a r p d i p a n g l e Steep initial failure dip angle accounts for the shape of the Coprates sturzstrom deposits. This is consistent with triggering from deep-seated gravitational slope deformation. S1S2S3 COPRATES LANDSLIDE Granular landslide modelling

17 Bovis and Jakob, 2000 July 29, 1998, debris flow Mount Meager, British Columbia antislope scarps Sudden debris flow after decades of slow deep-seated gravitational slope deformation Again a post-glacial event! historical rock avalanches 1998 debris flow

18 500 m Beinn Fhada (Long Mountain) Scotland Caledonides Post-glacial DSGS Post-DSGS landsliding antislope scarps eroded landslide deposits? micro-Candor Chasma landslide analog? vertical view oblique view 400 m

19 Possible origin from previous works 2. Is DSGS always paraglacial? Courtesy by J. Reitner Oberes Törl, Austrian Alps spreading ridge cohesion loss

20 postglacial trigger (ridge debuttressing/glacial unloading): 29 32 DSGS trigger studies in international peer-reviewed publications Kobayashi, K. Periglacial morphology of Japan. Biuletyn Periglacjalny 4, 15-36 (1956). Beck, A. C. Gravity faulting as a mechanism of topographic adjustment. New Zealand J. Geol. Geophys. 11, 191–199 (1968). Tabor, R. W. Origin of ridge-top depressions by large-scale creep in the Olumpic Mountains, Washington. Geol. Soc. Am. Bull. 82, 1811-1822 (1971). Radbrush-Hall, D. H., Varnes, D. J. & Savage, W. Z. Gravitational spreading of steep-sided ridges ("sackungen") in western United States. Int. Assoc. Eng. Geol. Bull. 14, 28-35 (1976). Bovis, M.J. Uphilll-facing (antislope) scarps in the Coast Mountains, southwest British Columbia. Geol. Soc. Am. Bull. 93, 804-812 (1982). Beget, J. E. Tephrochronology of antislope scarps on an alpine ridge near Glacier Peak, Washington, U.S.A. Arctic Alpine Res. 17, 143-152 (1985). Holmes, G. & Jarvis, J.J. Large-scale toppling with a sackung type deformation at Ben Attow, Scotland. Q. J. Eng. Geol. London 18, 287-289 (1985). Thorsen, G. W. Splitting and sagging mountains. Washington Geologic Newsletter 17, 3-1 (1992). Reitner, J., Lang, M. & van Husen, D. Deformation of high slopes in different rocks after würmian deglaciation in the Gailtal (Austria). Quaternary Int. 18, 43-51 (1993). Ego, F., Sébrier, M., Carey-Gailhardis, E. & Beate, B. Do the Billecocha normal faults (Ecuador) reveal extension due to lithospheric body forces in the northern Andes? Tectonophysics 265, 255-273 (1996). Bovis, M.J. & Jakob, M. The July 29, 1998, debris flow and landslide dam at Capricorn Creek, Mont Meager Volcanic Complex, southern Coast Mountains, British Columbia. Can. J. Earth Sci. 37, 1321-1334. Agliardi, F., Crosta, G., & Zanchi., A. Structural constraints on deep-seated slope deformation kinematics. Eng. Geol. 59, 83- 102 (2001). Smith, L.N. Columbia Mountain landslide: late-glacial emplacement and indications of future failure, Northwestern Montana, U.S.A. Geomorphology 41, 309-322 (2001). Jarman, D. & Ballantyne, C. K. Beinn Fhada, Kintal: An example of large-scale paraglacial rock slope deformation. Scottish Geog. J. 118, 159-168 (2002). Hermann, S. W. & Becker, L. P. Gravitational spreading ridges on the crystalline basement of the Eastern Alps (Niedere Tauern mountain range, Austria). Mitt.Österr. Geol. Ges. 94, 123-138 (2003). Holm, K., Bovis, M. & Jakob, M. The landslide response of alpine basins to post-Little Ice Age glacial thinning and retreat in southwestern British Columbia. Geomorphology 57, 201-216 (2004). Brückl, E. & Paroditis, M. Prediction of slope instabilities due to deep-seated gravitational creep. Natural Hazards Earth System Sci. 5, 155-172 (2005). Hetzel, R. & Hampel, A. Slip rate variations on normal faults during glacial-interglacial changes in surface loads. Nature 435, 81-84 (2005). Kinakin, D. & Stead, D. Analysis of the distributions of stress in natural ridge forms: implications for the deformation mechanisms of rock slopes and the formation of sackung. Geomorphology 65, 85-100 (2005) doi:10.1016/j.geomorph.2004.08.002. Korup, O. Geomorphic imprint of landslides on alpine river systems, southwest New Zealand. Earth Surf. Process. Landforms 30, 783-800 (2005). Ambrosi, C., & Crosta, G. B. Large sackung along major tectonic features in the Central Italian Alps. Eng. Geol. 83, 183-200 (2006). Hippolyte, J.-C., Brocard, G., Tardy, M., Nicoud, G., Bourlès, D., Braucher, R., Ménard, G. & Souffaché, B. The recent fault scarps of the western Alps (France): tectonic surface ruptures or gravitational sackung scarps? A combined mapping, geomorphic, levelling, and 10 Be dating approach. Tectonophysics 418, 255-276 (2006), doi:10.1016/j.tecto.2006.02.009. Hippolyte, J.-C., Tardy, M. & Nicould G. Les failles récentes des Grands-Moulins (Savoie) : un sackung (tassement gravitaire) majeur dans les Alpes françaises. C. R. Geosci. 338, 734-741 (2006). Hürlimann, M., Ledesma, A., Corominas, J. & Prat, P. C. The deep-seated slope deformation at Encampadana, Andorra: representation of morphologic features by numerical modelling. Eng. Geol. 83, 343-357 (2006). Jarman, D. Large rock slope failures in the Highlands of Scotland: Characterization, causes and spatial distribution. Engineering Geol. 83, 161-182 (2006). Turnbull, J.M. & Davies, T.R.H. A mass movement origin for cirques. Earth Surf. Process. Landforms 31, 1129-1148 (2006). Wilson, P., & Smith, A. Gomorphological characteristics and significance of Lat Quaternary paraglacial rock-slope failures on Skiddaw Group terrain, Lake District, northwest England. Geografiska Annaler 88, 237-252 (2006). Ustaszewski, M., Hampel, A. & Pfiffner, O. A. Composite faults in the Swiss Alps formed by the interplay of tectonics, gravitation and postglacial rebound: an integrated field and modelling study. Swiss. J. Geosci. (Eclogae Geologicae Helvetiae) 101, 223-235 (2008). Hippolyte, J.-C., Bourlès, D., Braucher, R., Carcaillet, J., Léanni, L., Arnold, M., & Aumaitre, G. Cosmogenic 10 Be dating of a sackung and its faulted rock glaciers, in the Alps of Savoy (France). Geomorphology 108, 312-320 (2009). Reitner, J., & Linner, M. Formation and preservation of large scale toppling related to alpine tectonic structures – eastern Alps. Austrian J. Earth Sci. 102, 69-80 (2009).

21 possible in theory never documented Rogers and Watkins, 2003 postglacial trigger (ridge debuttressing/glacial unloading): 29 32 DSGS trigger studies in international peer-reviewed publications

22 possible in theory never documented Rogers and Watkins, 2003 2 reported (controversial) cases Loma Prieta, 1989 (Ponti and Wells, 1991) Northridge, 1994 (Harp and Gibson, 1996) postglacial trigger (ridge debuttressing/glacial unloading): 29 32 DSGS trigger studies in international peer-reviewed publications

23 ridge edification by river incision and evaporite flow Somali plateau (Mège et al., submitted) Canyonlands grabens-type spreading possible in theory never documented Rogers and Watkins, 2003 2 reported (controversial) cases Loma Prieta, 1989 (Ponti and Wells, 1991) Northridge, 1994 (Harp and Gibson, 1996) postglacial trigger (ridge debuttressing/glacial unloading): 29 + 32 DSGS trigger studies in international peer-reviewed publications sandstone gypsum

24 Mège et al., submitted summit graben gypsum sandstone Gravitational spreading, Somali plateau

25 possible in theory never documented Rogers and Watkins, 2003 2 reported (controversial) cases Loma Prieta, 1989 (Ponti and Wells, 1991) Northridge, 1994 (Harp and Gibson, 1996) 1 unelucidated case (seismic shaking dismissed) South Italy (Rizzo and Leggeri, 2004) postglacial trigger (ridge debuttressing/glacial unloading): 29 + ridge edification by river incision and evaporite flow Somali plateau (Mège et al., submitted) Canyonlands grabens-type spreading 32 DSGS trigger studies in international peer-reviewed publications

26 -- Deglaciation seems by far to be the most likely DSGS trigger in Valles Marineris --

27 3. Are there other hints of ancient glaciers in Valles Marineris? -- Deglaciation seems by far to be the most likely DSGS trigger in Valles Marineris --

28 Molnia, 2004 Tana glacier, Alaska Ius Chasma trimlines formerly interpreted as normal fault scarps… Mège, 1994 Peulvast et al., 2001 … but no clear length/displacement scaling law and poor segmentation! trimline (highest extent of glacier) 600 m

29 GER YON M ON T E S I U S C H A S M A F L O O R I U S landslide deposits Possible trimlines I U S C H A S M A 10 km

30 Candor Chasma Svalbard Longyearbreen glacier Evans, Quat. Sci. Rev., 2009 Thrilling Candor Chasma analog in Svalbard 5 km Glacial receding since Little Ice Age trimline ?? 500 m 600 m subglacial polished rocks trimline chasma floor

31 Is a glacier still present in Candor Chasma? ground moraine -3000 m -4000 m -4500 m TRIMLINE EXPOSED SUBGLACIAL ROCKS -4200 m ILDs MASKED GLACIER? 2 km +1200 m

32 Central Candor Chasma northeastern Ius Chasma 1 km 100 m 200 m 2 km Receding glaciers Valley glaciers in northern Nepal, Higher Himalaya humocky topography depending on local melting conditions and relative ice/rock ratio ice melting

33 2 km 100 m Ius Chasma Glacial valley in southern Tibet GERYON MONTES (DSGS) MELAS CHASMA

34 smectite + massive hydrated silicates at base of sagging ridge sulfate (kieserite + polyhydrated) + massive hydrated silicates Roach et al., in press Ridge cohesion loss by groundwater flow deep-seated gravitational slope deformation zone Sublimation residue of ice+volcanic aerosol mixture weathering products Correlation with hyperspectral modeling results Niles and Michalski, 2009 Kobayashi, 1956 Similar inferences can be made from hyperspectral modeling in Candor Chasma Gendrin et al., 2005, Le Deit et al., 2008 I U S C H A S M A

35 From trimline height, preliminary measurements suggest that the thickness of some glaciers may have been ~ 0.5 - 2 km. Conclusions Wallrock has been very weak since deglaciation, providing a mechanical framework for widespread mass wasting processes during the Amazonian (Peulvast et al., 2001). Morphology and structure of intra- and inter-chasma ridges in Valles Marineris point to the existence of ancient valley glaciers in all the major chasmata, hence equatorial glaciations (it can be shown that the glaciers producing DSGS were present before ILD deposition).


Download ppt "Destabilization of Valles Marineris wallslopes by retreat of ancient glaciers Daniel MEGE Olivier BOURGEOIS Planetology and Geodynamics Laboratory CNRS."

Similar presentations


Ads by Google