@article{fdi:010061182,
  title = {{C}osmogenic {H}e-3 production rate in the high tropical {A}ndes (3800 m, 20 degrees {S}) : implications for the local last glacial maximum},
  author = {{B}lard, {P}. {H}. and {L}ave, {J}. and {S}ylvestre, {F}lorence and {P}laczek, {C}. {J}. and {C}laude, {C}. and {G}aly, {V}. and {C}ondom, {T}homas and {T}ibari, {B}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}o improve both precision and accuracy of cosmic-ray exposure dating methods, there is a crucial need of calibration sites constraining the production rate of cosmogenic isotopes. {T}his is particularly true in the high tropical area, where existing scaling models present significant discrepancies. {T}his study presents a new calibration site for cosmogenic {H}e-3, located at 3800 m in the tropical {A}ltiplano (19.9 degrees {S}, 67.6 degrees {W}), on the southern flank of the {T}unupa volcano, in the vicinity of the {S}alar de {U}yuni. {I}t consists in a fluvio-glacial outwash that is stratigraphically bracketed by two successive lacustrine shorelines. {T}hese shorelines are well-dated by {C}-14 and {U}-series dating (n = 57), allowing determination of the age of the boulder field at the surface of the delta, at 15.3 +/- 0.5 ka (let). {E}leven andesitic boulders were sampled on this fluvio-glacial surface and the cosmogenic {H}e-3 contents of their pyroxene phenocrysts and amphiboles was analyzed. {T}he nucleogenic contribution from {L}i-6 capture is well-constrained by determining the ({U}-{T}h-{S}m)/{H}e-4 age of these rocks. {T}his correction is minimal (<2%) and does not represent a significant source of uncertainty. {C}osmogenic {H}e-3 ({H}e-c) concentrations are characterized by a very high reproducibility: 10 samples overlap within 10- analytical error. {T}his suggests that pre- or post-deposition processes have minimal impact on the 3{H}ec data. {F}urthermore, there is no correlation between the {L}i and the {H}e-3(c) content of the mineral, indicating that {H}e-3(c) production from cosmogenic thermal neutron is here negligible. {C}ombined with the absolute dating of the delta, these {H}e-3(c) data yield a local production rate of 999 +/- 38 (1 sigma) at g(-1) yr(-1), at 3800 m and 19.89 {S}. {A}fter scaling with the time dependent scaling scheme of ({S}tone, 2000), this result yields a rate of 121 +/- 5 (1 sigma) at g(-1) yr(-1) at high latitude and sea level. {T}his new calibration is the highest among the existing global dataset {I}t will thus permit the establishment of new robust glacial chronologies in the high {T}ropics, with an uncertainty lower than 5% at 1 sigma. {S}uch precision may have important implications in paleoclimatology, notably because it will allow comparison with other well-dated paleoclimatic archives. {I}ncluding this new data, the updated global {H}e-3(c) production rate is 122 +/- 15 at g(-1) yr(-1), using the time-dependent scaling of {S}tone (2000). {T}he new site-specific {H}e-3(c) production rate is used here to refine glacier fluctuations on {C}erro {T}unupa, confirming that the local last glacial maximum was synchronous with the {L}ake {T}auca highstand (15.5 ka). {D}ata also suggest that a dramatic glacial retreat occurred at about 15 ka, few hundred years before the {L}ake {T}auca regression, synchronously with the onset of the {B}olling-{A}llerod.},
  keywords = {cosmogenic {H}e-3 ; production rate ; {A}ltiplano ; {H}einrich 1 ; {L}ake {T}auca ; {T}unupa ; {ANDES} ; {ZONE} {TROPICALE} ; {BOLIVIE}},
  booktitle = {},
  journal = {{E}arth and {P}lanetary {S}cience {L}etters},
  volume = {377},
  numero = {},
  pages = {260--275},
  ISSN = {0012-821{X}},
  year = {2013},
  DOI = {10.1016/j.epsl.2013.07.006},
  URL = {https://www.documentation.ird.fr/hor/fdi:010061182},
}