|
Boletín de la Sociedad Geológica Mexicana Volumen 69, núm. 2, 2017, p. 299 ‒ 311 |
 |
Perforación profunda en el lago de Chalco: reporte técnico
Socorro Lozano-García, Erik T. Brown, Beatriz Ortega, Margarita Caballero, Josef Werne, Peter J. Fawcett, Antje Schwalb, Blas L. Valero-Garcés, Douglas Schnurrenberger, Ryan O´Grady, Mona Stockhecke, Byron Steinman, Enrique Cabral-Cano, Cecilia Caballero, Susana Sosa-Nájera, Ana María Soler, Liseth Pérez, Anders Noren, Amy Myrbo, Matthias Bücker, Nigel Wattrus, Alejandra Arciniega, Thomas Wonik, Sebastian Watt, Dervla Kumar, Carmen Acosta, Ivan Martínez, Rafael Cossio, Troy Ferland, Filiberto Vergara-Huerta
Socorro Lozano-García (This email address is being protected from spambots. You need JavaScript enabled to view it.)
Susana Sosa-Nájera
Liseth Pérez
Carmen Acosta
Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, C.P. 04510, Ciudad de México, México.
Erik T. Brown
Mona Stockhecke
Byron Steinman
Nigel Wattrus
University of Minnesota at Duluth, Large Lakes Observatory, MN 55812, USA.
Beatriz Ortega
Margarita Caballero
Enrique Cabral-Cano
Cecilia Caballero
Ana María Soler
Alejandra Arciniega
Ivan Martínez
Rafael Cossio
Filiberto Vergara-Huerta
Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria, C.P. 04510, Ciudad de México, México.
Josef Werne
Dervla Kumar
Troy Ferland
University of Pittsburgh, Department of Geology and Environmental Science, PA 15260, USA.
Peter J. Fawcett
University of New Mexico, Department of Earth and Planetary Sciences, NM 87131, USA.
Antje Schwalb
Institute of Geosystem and Bioindication, Technical University of Braunschweig, 38106 Braunschweig, Germany.
Blas L. Valero Garcés
Instituto Pirenaíco de Ecología, Avda. Montaña 1005, 50059 Zaragoza, España.
Douglas Schnurrenberger
Ryan O´Grady
Anders Noren
Amy Myrbo
CSDCO/LacCore, University of Minnesota Minneapolis, MN 55455, USA.
Matthias Bücker
Departmento de Geofísica, Instituto Steinmann, Universidad de Bonn, Meckenheimer Allee 176, 53115 Bonn, Alemania.
Grupo de Geofísica, Departmento de Gedesia y Geoinformation, Viena Universidad de Tecnología, Gußhausstr. 25-29, 1040 Viena, Austria.
Thomas Wonik
Leibniz-Institut für Angewandte Geophysik LIAG, Hannover, Germany.
Sebastian Watt
University of Birmingham, School of Geography, Earth and Environmental Sciences, UK.
Abstract
This paper presents a short description of the coring operations undertaken to recover the full lacustrine sedimentary sequence from Chalco. Geophysical techniques were used to determine the distribution and thickness of the sediments in order to select the drilling site. Resonance frequencies determined from H/V spectral ratios were used to determine an area where lake sediments reached 300 m thickness. Electromagnetic survey showed two changes in electric resistivity which were related to changes in sediment composition, the first from 100 to 120 m, related to an increase in volcanoclastic sediments and the second from 330 to 400 m related to the presence of a basaltic flows. Three wells were drilled with continuous recovery, reaching depths of 420 m in well A, 310 in B and 520 in C. Samples for geomicrobiological and metagenomics studies were collected during drilling operations. A total of 1152 m of core sediments were recovered reaching a maximum depth of 520 m. Recovery percentages were between 88 and 92 % in the three wells. Magnetic susceptibility analyses in the three sequences show that the first 260 m are mostly lake sediments, between 260 and 300 m sediments are coarser and below 300 m they are mostly volcaniclastic. Analysis of the sedimentary sequence of Lake Chalco that covers the last ~300000 years will allow documenting and extending the knowledge of climate variability in area, the paleoenvironmental history, basin closure history, lacustrian system development and volcanic activity recurrence. Studies of the physical properties of this sequence will be important for seismic propagation and basin structure modeling, and also will improve modeling of the subsidence process that this region experiences.
Keywords: Lacustrian sediments, paleoclimate, volcanism, Basin of Mexico, Chalco.
