@article{fdi:010044179,
  title = {{L}ava flow internal structure found from {AMS} and textural data : an example in methodology from the {C}haine des {P}uys, {F}rance},
  author = {{L}oock, {S}. and {D}iot, {H}. and de {V}ries, {B}. {V}. and {L}auneau, {P}. and {M}erle, {O}livier and {V}adeboin, {F}. and {P}etronis, {M}. {S}.},
  editor = {},
  language = {{ENG}},
  abstract = {{A}nisotropy of magnetic susceptibility ({AMS}) data analysis is a convenient method used to investigate strain and flow during lava flow emplacement. {I}n order to make a sound interpretation, the origin of the {AMS} signal must be verified. {T}wo questions must be answered: 1) what phase, or phases carry the {AMS} signal and 2) when was the {AMS} fabric acquired? {T}he verification steps themselves can provide extra data for interpreting lava flow conditions. {H}ere, we present a methodology to answer the two questions in a 6 km-long {C}haine des {P}uys trachybasaltic lava flow that descended into the future site of {C}lermont {F}errand ({F}rance) 45,000 years ago. {K}nowledge of lava flow emplacement will be useful specifically to this site, if a reactivation of the volcanic chain occurs. {T}he results are also of more general interest to understand lava flow emplacement dynamics. {C}urie {T}emperature, thin sections (optical, {SEM}, microprobe analysis) and {F}irst {O}rder {R}eversal {C}urves ({FORCS}) indicate that the {AMS} carriers are multidomain ({MD}) and pseudosingle-domain ({PSD}) titanomagnetites. 3-{D} microlite fabric data compared with {AMS}-fabric elements shows that the {AMS} ellipsoid is produced by a late-stage microlite fabric deformation, just before complete immobilisation. {W}ith this knowledge, and with field structural observations, a vertical section through the lava flow is analysed. {T}wo {AMS} parameters: magnetic lineation (k(max)), and degree of anisotropy ({A}) are significant. {T}he k(max) displays opposing plunge directions, suggesting reversing simple shear sense. {S}ome k(max) plunge reversals coincide with degree of anisotropy breaks, also indicating the existence of texturally distinct units. {A}lso, k(max) plunges can be greater than 45 degrees indicating a vertical pure shear component consistent with inflation. {D}egree of anisotropy breaks and k(max) changes correlate with variations in vesicle and/or phenocryst concentrations, underlining that the distinct layers could have been theologically different. {B}ased on these observations. we propose a qualitative late-stage velocity profile for the flow that requires several distinct layers. {W}e propose that the flow was layered into distinct rheology units, linked to pre-eruption or in-flow variability. {T}his suggests that during the late stage of emplacement, the flow was subdivided into at least 5 distinct compartments, and each had a different flow history and different behaviour.},
  keywords = {{AMS} ; lava flow emplacement ; {FORC} ; microlite fabric ; degree of ; anisotropy ; k(max) plunge ; lava layering},
  booktitle = {},
  journal = {{J}ournal of {V}olcanology and {G}eothermal {R}esearch},
  volume = {177},
  numero = {4},
  pages = {1092--1104},
  ISSN = {0377-0273},
  year = {2008},
  DOI = {10.1016/j.jvolgeores.2008.08.017},
  URL = {https://www.documentation.ird.fr/hor/fdi:010044179},
}