Initial results of an electrical resistivity survey of the volcanosedimentary sequence of the Valsequillo basin in central Mexico are presented. The volcanosedimentary deposits preserve rich paleontological , paleoclimatic and paleoenvironmental records,
which include extinct megafauna remains
associated with human artifacts. The report of
possible 38 ka old human footprint tracks in
the Xalnene tuff attracted renewed interest in
the basin stratigraphy. We examine the shallow
stratigraphic sequence in the Xalnene tuff outcrop
plain northwest of Cerro Toluquilla volcano using
vertical resistivity soundings (VES). Inversion
models of VES soundings show a layered structure
of high and low resistivity units, which characterize
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and volcanic rocks. 2-D resistivity cross sections
document three major units corresponding to
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deep basin lying on volcanic rocks. Resistivity
models provide further support for the association
of Xalnene tuff with the Toluquilla volcano and
emplacement of the pyroclastic deposits on a
shallow lacustrine environment. The resistivity
cross sections constrain the thickness of the
tuff layers and underlying lacustrine sediments.
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work provide insight on the possible origin of the
apparent tracks, which seem to develop from
erosion processes acting on quarrying marks.
Further analysis and experimental evidence is
required to understand the morphology and
weathered patterns. The tuff layers are being
removed by quarrying operations and the outcrops
significantly altered. Adequate conservation
measurements should be implemented to preserve
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Key words: Valsequillo b