Sedimentary stratigraphy of Lake Chalco (Central Mexico) during its formative stages
Por:
Martinez-Abarca, Rodrigo, Ortega-Guerrero, Beatriz, Lozano-Garcia, Socorro, Caballero, Margarita, Valero-Garces, Blas, McGee, David, Brown, Erik T., Stockhecke, Mona, Hodgetts, Alastair G. E.
Publicada:
1 oct 2021
Ahead of Print:
1 ene 2021
Categoría:
Earth and planetary sciences (miscellaneous)
Resumen:
Lake Chalco lies south of the Basin of Mexico and has been the subject
of studies related to Late Quaternary climate variability. In 2016, the
International Continental Scientific Drilling Program ``MexiDrill
Project'' recovered a 520-m sediment record from Lake Chalco. Magnetic
susceptibility measurements revealed substantial changes in sediment
physical properties between 343 and 285 m depth, suggesting changes in
composition associated with fluctuations in the depositional
environment. We targeted sediments in the 343-285 m interval for
high-resolution facies analysis, to develop a model of Lake Chalco
formation. We identified three facies associations, using sediment
composition, texture, mineralogy and micro-morphological
characteristics: (1) detrital facies, consisting of laminated silt,
massive sand, stratified silty sand, clast-supported gravel and
matrix-supported gravel; (2) biogenic facies, which include diatom ooze
and bivalve coquina; and (3) volcaniclastic facies, represented by
clast-supported pumice deposits. We propose that formation of Lake
Chalco occurred in four stages, which we identified by changes in
sediment characteristics. The first stage was an alluvial delta
environment, in which debris and hyper-concentrated flows were the main
sediment transport agents. The second was characterized by turbulent
flows in a fluvial deltaic environment, which alternated with laminar
flows associated with floodplains. The third stage was a time of
fluvio-lacustrine transition in the basin, with formation of the
previously identified Paleo-Chalco-I Lake, in response to wet
conditions. During the fourth stage, a deep eutrophic lake formed
(Paleo-Chalco-II), with an origin that appears to have been related to
regional volcanism. Our working age-depth model indicates establishment
of the lake at ca. 400 +/- 46 ka. This paper presents the only available
record of the transition from alluvial to lacustrine sedimentation of
Lake Chalco. Our results allow us to establish (1) how the lake was
formed and what the phases of its development were, (2) how a major
volcanic event altered and transformed the lacustrine sedimentation, and
(3) which climatic conditions dominated during the lake formation. The
age for the onset of the lacustrine sedimentation in Chalco is for the
first time constrained to around 400 ka. This enables to expand our
knowledge of the climate for a time for which there is no information
from terrestrial records of tropical North America.
Filiaciones:
Martinez-Abarca, Rodrigo:
Ortega-Guerrero, B (Corresponding Author), Univ Nacl Autonoma Mexico, Inst Geofis, Mexico City 04510, DF, Mexico. Martinez-Abarca, Rodrigo, Univ Nacl Autonoma Mexico, Posgrad Ciencias Tierra, Mexico City 04510, DF, Mexico. Ortega-Guerrero, Beatriz
Ortega-Guerrero, Beatriz:
Ortega-Guerrero, B (Corresponding Author), Univ Nacl Autonoma Mexico, Inst Geofis, Mexico City 04510, DF, Mexico. Martinez-Abarca, Rodrigo, Univ Nacl Autonoma Mexico, Posgrad Ciencias Tierra, Mexico City 04510, DF, Mexico. Ortega-Guerrero, Beatriz
Lozano-Garcia, Socorro:
Ortega-Guerrero, B (Corresponding Author), Univ Nacl Autonoma Mexico, Inst Geofis, Mexico City 04510, DF, Mexico. Martinez-Abarca, Rodrigo, Univ Nacl Autonoma Mexico, Posgrad Ciencias Tierra, Mexico City 04510, DF, Mexico. Ortega-Guerrero, Beatriz
Caballero, Margarita:
Ortega-Guerrero, B (Corresponding Author), Univ Nacl Autonoma Mexico, Inst Geofis, Mexico City 04510, DF, Mexico. Martinez-Abarca, Rodrigo, Univ Nacl Autonoma Mexico, Posgrad Ciencias Tierra, Mexico City 04510, DF, Mexico. Ortega-Guerrero, Beatriz
Valero-Garces, Blas:
Ortega-Guerrero, B (Corresponding Author), Univ Nacl Autonoma Mexico, Inst Geofis, Mexico City 04510, DF, Mexico. Martinez-Abarca, Rodrigo, Univ Nacl Autonoma Mexico, Posgrad Ciencias Tierra, Mexico City 04510, DF, Mexico. Ortega-Guerrero, Beatriz
McGee, David:
Ortega-Guerrero, B (Corresponding Author), Univ Nacl Autonoma Mexico, Inst Geofis, Mexico City 04510, DF, Mexico. Martinez-Abarca, Rodrigo, Univ Nacl Autonoma Mexico, Posgrad Ciencias Tierra, Mexico City 04510, DF, Mexico. Ortega-Guerrero, Beatriz
Stockhecke, Mona:
Ortega-Guerrero, B (Corresponding Author), Univ Nacl Autonoma Mexico, Inst Geofis, Mexico City 04510, DF, Mexico. Martinez-Abarca, Rodrigo, Univ Nacl Autonoma Mexico, Posgrad Ciencias Tierra, Mexico City 04510, DF, Mexico. Ortega-Guerrero, Beatriz
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