@article{fdi:010070021,
  title = {{C}ontrasting origin of two clay-rich debris flows at {C}ayambe {V}olcanic {C}omplex, {E}cuador},
  author = {{D}etienne, {M}. and {D}elmelle, {P}. and {G}uevara, {A}. and {S}amaniego, {P}ablo and {O}pfergelt, {S}. and {M}othes, {P}. {A}.},
  editor = {},
  language = {{ENG}},
  abstract = {{W}e investigate the sedimentological and mineralogical properties of a debris flow deposit west of {C}ayambe {V}olcanic {C}omplex, an ice-clad edifice in {E}cuador. {T}he deposit exhibits a matrix facies containing up to 16 wt% of clays. {H}owever, the stratigraphic relationship of the deposit with respect to the {C}anguahua {F}ormation, a widespread indurated volcaniclastic material in the {E}cuadorian inter-{A}ndean {V}alley, and the deposit alteration mineralogy differ depending on location. {T}hus, two different deposits are identified. {T}he {R}io {G}ranobles debris flow deposit (similar to 1 km(3)) is characterised by the alteration mineral assemblage smectite + jarosite, and sulphur isotopic analyses point to a supergene hydrothermal alteration environment. {T}his deposit probably derives from a debris avalanche initiated before 14-21 ka by collapse of a hydrothermally altered rock mass from the volcano summit. {I}n contrast, the alteration mineralogy of the second debris flow deposit, which may itself comprise more than one unit, is dominated by halloysite + smectite and relates to a shallower and more recent (< 13 ky) mass movement of high-altitude (> 3200 m) volcanic soils. {O}ur study reinforces the significance of hydrothermal alteration in weakening volcano flanks and in favouring rapid transformation of a volcanic debris avalanche into a clay-rich debris flow. {I}t also demonstrates that mineralogical analysis provides crucial information for resolving the origin of a debris flow deposit in volcanic terrains. {F}inally, we posit that slope instability, promoted by ongoing subglacial hydrothermal alteration, remains a significant hazard at {C}ayambe {V}olcanic {C}omplex.},
  keywords = {{D}ebris flow deposit ; {V}olcanic debris avalanche ; {H}ydrothermal alteration ; {C}lay minerals ; {C}ayambe{V}olcanic {C}omplex ; {EQUATEUR}},
  booktitle = {},
  journal = {{B}ulletin of {V}olcanology},
  volume = {79},
  numero = {4},
  pages = {art. 27 [14 p.]},
  ISSN = {0258-8900},
  year = {2017},
  DOI = {10.1007/s00445-017-1111-2},
  URL = {https://www.documentation.ird.fr/hor/fdi:010070021},
}