@article{fdi:010035681,
  title = {{N}eogene and quaternary ignimbrites in the area of {A}requipa, {S}outhern {P}eru : stratigraphical and petrological correlations},
  author = {{L}ebti, {P}.{P}. and {T}houret, {J}.{C}. and {W}orner, {G}. and {F}ornari, {M}ichel},
  editor = {},
  language = {{ENG}},
  abstract = {{T}his study focuses on the correlation of four newly identified rhyolitic ignimbrites located around {A}requipa, which were previously described as a single ignimbrite sheet: (1) {T}he {R}io {C}hili {I}gnimbrite (ca. 13.33 {M}a) crops out in the {R}io {C}hili canyon and consists of a cooling unit of non-welded to partially welded, massive, crystal-rich lapilli tuff. {T}his ignimbrite represents the base of the {N}eogene ignimbrite succession in the {A}requipa area and may be stratigraphically equivalent to the 14-13{M}a {H}uaylillas {I}gnimbrites in southern {P}eru. (2) {T}he second voluminous (similar to 20km(3)) and widespread {L}a {J}oya {I}gnimbrite sheet (ca. 4.87{M}a) filled the {A}requipa depression. {I}ts probable source is now buried underneath the {C}hachani volcanic complex. {T}he {L}a {J}oya {I}gnimbrite covers both the {A}requipa {B}atholith toward the {R}io {V}itor {P}iedmont and also part of the {A}ltiplano to the {E}ast and {N}orth of the {C}hachani complex. (3) {T}he {A}requipa {A}irport {I}gnimbrite ({AAI}) sheet (ca. 1.6{M}a, similar to 18km(3)), the third and latest infill of the {A}requipa basin, consists of a lower white, columnar jointed, massive lapilli tuff, indurated by vapor-phase recrystallization, and is overlain by an upper, pink, lithic-rich, non-welded, massive lapilli-tuff. {T}he source of this ignimbrite is also buried underneath the {C}hachani complex, as indicated by anisotropy of magnetic susceptibility measurements and component lithology. (4) {T}he {Y}ura non-welded pumice-flow deposits (ca. 1.02 {M}a, 1.5 km(3)) are restricted to the northern and western flanks of the {C}hachani complex and may correlate with tuffs of the {C}apillune {F}ormation on the {A}ltiplano. {A}ll ignimbrites are high-{K} calc-alkaline to alkaline rhyolites, which contain variable amounts of plagioclase, biotite, quartz, sanidine, and {F}e-{T}i oxides. {T}he modal composition of mineral phases and chemistry of amphiboles and biotites are useful for distinguishing the ignimbrites. {S}pecific geochemical fingerprints, such as {S}r, {Y}, {R}b, {B}a, {C}s, {REE}, and {S}r isotopes were effective discriminator elements. {M}agmatic differentiation, crustal residence time and contamination, and source melting processes are discussed in order to explain compositional variations. {T}he older {L}a {J}oya {I}gnimbrite and {R}io {C}hili {I}gnimbrite reflect initial wetter crustal melts closer to granite composition, whereas with time the younger {A}requipa {A}irport {I}gnimbrite and {Y}ura {T}uffs initial melts are slightly less evolved and dryer due to more extensive crustal melting. {T}he voluminous (> 40km(3)) {N}eogene ignimbrites of the {A}requipa area were produced by three major explosive volcanic pulses in the {C}entral {V}olcanic {Z}one of southern {P}eru, whose genetic relation with tectonic uplift and crustal thickening of the {A}ndean {C}ordillera are still a matter of debate. (c) 2006 {E}lsevier {B}.{V}. {A}ll rights reserved.},
  keywords = {ingnimbrite ; {P}eru ; stratigraphy ; {A}r 40 {A}r 39 ages ; petrology ; correlation},
  booktitle = {},
  journal = {{J}ournal of {V}olcanology and {G}eothermal {R}esearch},
  volume = {154},
  numero = {3-4},
  pages = {251--275},
  ISSN = {0377-0273},
  year = {2006},
  DOI = {10.1016/j.jvolgeores.2006.02.014},
  URL = {https://www.documentation.ird.fr/hor/fdi:010035681},
}