Holocene palaeoenvironmental variability in the western Trans Mexican Volcanic Belt: insights of the source of the actual climatic conditions from a geochemical study of Lake Etzatlán-Magdalena
Abstract
Lake sediments have shown through so many examples that are good tool to infer paleoenvironmental conditions of a region. In this study, we extend palaeoenvironmental information of western sector of the Trans-Mexican Volcanic Belt by using geochemical proxies and magnetic susceptibility in sediments deposited over the Holocene in the Etzatlan-Magdalena Basin. The reconstructed millennial-scale variability of precipitation and aridity were compared with proxy records indicating dynamics of ITCZ and ENSO in order to understand the influence of both these forcings. Paleolake Etzatlán-Magdalena is located in the western sector of the Transmexican Volcanic Belt, in the Mexican state of Jalisco. A 122 cm long sequence was analyzed. Sedimentary sequence is characterized by massive strata of dark brown-black color, silty-argillaceous grain size and sedimentation rates between 0.08 and 0.24 mm/yr. An age model for the sedimentary sequence was created from four stratigraphically concordant AMS 14C dates. The age at the bottom of the sequence is 9,600 cal yr BP and the sequence has continuity along the time. To investigate the controlling factors in the sedimentation of the sequence, total organic/inorganic carbon, X ray fluorescence analysis and magnetic susceptibility measurements were performed on the sequence. Proxy data analyzed on these sediments indicate generally wetter conditions during early and late Holocene and arid conditions during middle Holocene. A comparison with other proxy records from different parts of Mexico and records indicating ITCZ and ENSO suggests that variations in hydroclimate during the middle and late Holocene was caused by different amounts of summer precipitation, and at the top of the sequence autumn precipitation through formation of tropical cyclones into the region is inferred.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMPP13B2087C
- Keywords:
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- 1051 Sedimentary geochemistry;
- GEOCHEMISTRYDE: 1165 Sedimentary geochronology;
- GEOCHRONOLOGYDE: 1520 Magnetostratigraphy;
- GEOMAGNETISM AND PALEOMAGNETISMDE: 1890 Wetlands;
- HYDROLOGY