Sedimentary stratigraphy of Lake Chalco (Central Mexico) during its formative stages

Lake Chalco lies south of the Basin Mexico and has been subject studies related to Late Quaternary climate variability. In 2016, International Continental Scientific Drilling Program “MexiDrill Project” recovered a 520-m sediment record from Chalco. Magnetic susceptibility measurements revealed substantial changes in physical properties between 343 285 m depth, suggesting composition associated with fluctuations depositional environment. We targeted sediments 343–285 interval for high-resolution facies analysis, develop model formation. identified three associations, using composition, texture, mineralogy micro-morphological characteristics: (1) detrital facies, consisting laminated silt, massive sand, stratified silty clast-supported gravel matrix-supported gravel; (2) biogenic which include diatom ooze bivalve coquina; (3) volcaniclastic represented by pumice deposits. propose that formation occurred four stages, we characteristics. The first stage was an alluvial delta environment, debris hyper-concentrated flows were main transport agents. second characterized turbulent fluvial deltaic alternated laminar floodplains. third time fluvio-lacustrine transition basin, previously Paleo-Chalco-I Lake, response wet conditions. During fourth stage, deep eutrophic lake formed (Paleo-Chalco-II), origin appears have regional volcanism. Our working age-depth indicates establishment at ca. 400 ± 46 ka. This paper presents only available lacustrine sedimentation results allow us establish how what phases its development were, major volcanic event altered transformed sedimentation, climatic conditions dominated during age onset is constrained around enables expand our knowledge there no information terrestrial records tropical North America.