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Five Younger Dryas black mats in Mexico and their stratigraphic and paleoenvironmental context

Israde-Alcántara, I and Domínguez-Vázquez, G and Gonzalez, S and Bischoff, J and West, A and Huddart, D (2017) Five Younger Dryas black mats in Mexico and their stratigraphic and paleoenvironmental context. Journal of Paleolimnology. ISSN 0921-2728

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Abstract

The Younger Dryas interval (YD) was a period of widespread, abrupt climate change that occurred between 12,900 and 11,700 cal yr BP (10,900–10,000 14 C BP). Many sites in the Northern Hemisphere preserve a sedimentary record across the onset of the YD interval, including sites investigated in sedimentary basins located in central Mexico (Chapala, Cuitzeo, Acambay), the Basin of Mexico (Tocuila), and northern Mexico (El Cedral). Deposits consist of lacustrine or marginal lake sediments that were deposited during the Pleistocene and the Holocene. At the Tocuila and Acambay sites, Pleistocene fossil vertebrate assemblages, mainly mammoths (Mammuthus columbi), are found in association with a distinctive organic layer, sometimes called the black mat that formed during the YD. At the Chapala, Cuitzeo, Acambay, and Tocuila sites the black mats contain a suite of distinctive microscopic and mineralogical signatures and are accompanied by a sharp change in the depositional environments as supported by diatom and pollen studies reported here. The signatures include magnetic, Fe-rich microspherules, silica melted droplets with aerodynamic shapes (tektites), large amounts of charcoal, and sometimes nanodiamonds (Cuitzeo), all of which were deposited at the onset of the YD. The geochemistry of the microspherules indicates that they are not anthropogenic, authigenic or of cosmic or volcanic origin, and instead, were produced by melting and quenching of terrestrial sediments. Here, we present the stratigraphy at five field sites, the analyses of magnetic microspherules, including major element composition and scanning electron microscopy images. All of these materials are associated with charcoal and soot, which are distinctive stratigraphic markers for the YD layer at several sites in Mexico. © 2017 Springer Science+Business Media B.V.

Item Type: Article
Uncontrolled Keywords: 0403 Geology, 0406 Physical Geography And Environmental Geoscience
Subjects: C Auxiliary Sciences of History > CC Archaeology
G Geography. Anthropology. Recreation > GB Physical geography
G Geography. Anthropology. Recreation > GE Environmental Sciences
Divisions: Natural Sciences and Psychology
Publisher: Springer Verlag
Date Deposited: 23 Aug 2017 12:09
Last Modified: 23 Aug 2017 12:09
DOI or Identification number: 10.1007/s10933-017-9982-y
URI: http://researchonline.ljmu.ac.uk/id/eprint/6978

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