Publication: Combinación de métodos de datación en cronologías paleosísmicas: el ejemplo de El Saltador (Falla de Alhama de Murcia)
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2016
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Sociedad Geológica de España.
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Abstract
Presentamos la cronología de paleoterremotos establecida para la rama sur de la Falla de Alhama de Murcia (Béticas Orientales) a partir del estudio paelosismológico de la localidad de el Saltador (Lorca). Mostramos la aplicación combinada de cuatro métodos de datación; luminiscencia en cuarzo y feldespato (OSL en cuarzo y pIRIRSL), datación de series de Uranio en carbonatos pedogénicos, y radiocarbono. Para acotar la edad de los paleoterremotos con la mejor definición posible, se han integrado las edades de las capas que definen temporalmente los paleosismos en un modelo deposicional. Para ello se usó el programa OxCal (versión 4.2), que realiza un tratamiento estadístico bayesiano de las funciones de probabilidad de las edades de materiales afectados según un orden estratigráfico conocido y calcula la recurrencia media y la recurrencia particular entre eventos sucesivos. La secuencia de materiales aluviales muestra el registro de ocho eventos paleosísmicos ocurridos desde hace 54,3 ± 9,1 ka. El tiempo de recurrencia medio varía entre 3,5- y 5,3 ka , localizándose el último evento entre el s. XIII y el s. XVIII.
We present a chronology of paleo-earthquakes established at El Saltador (Lorca), a paleoseismical site in the southern branch of the Alhama de Murcia Fault (Eastern Betics). Because of the difficulties in dating the affected sediments using a single dating approach, we combined four types of methods; Two of them based on the luminescence of quartz and feldspar (Quartz-OSL and pIR-IRSL), U-series on pedogenic carbonates and radiocarbon dating. To obtain the best possible accuracy for the age of each paleoearthquake, we integrated the age of the layers that constrain the seismic events into a depositional model. To this end, we relied on the OxCal program (version 4.2), which performs a Bayesian statistical treatment of the probability functions of the ages assigned to a sequence of layers of known stratigraphical order, at the time that it provides the average recurrence and the single recurrence between successive events. The sequence of alluvial deposits analyzed shows the record of eigth paleoseismic events occurred since 54,3 ± 9.1 ka. The average recurrence intervals ranges between 3,5- and 5,3 ka with the last event taking place between the XIII and XVII centuries.
We present a chronology of paleo-earthquakes established at El Saltador (Lorca), a paleoseismical site in the southern branch of the Alhama de Murcia Fault (Eastern Betics). Because of the difficulties in dating the affected sediments using a single dating approach, we combined four types of methods; Two of them based on the luminescence of quartz and feldspar (Quartz-OSL and pIR-IRSL), U-series on pedogenic carbonates and radiocarbon dating. To obtain the best possible accuracy for the age of each paleoearthquake, we integrated the age of the layers that constrain the seismic events into a depositional model. To this end, we relied on the OxCal program (version 4.2), which performs a Bayesian statistical treatment of the probability functions of the ages assigned to a sequence of layers of known stratigraphical order, at the time that it provides the average recurrence and the single recurrence between successive events. The sequence of alluvial deposits analyzed shows the record of eigth paleoseismic events occurred since 54,3 ± 9.1 ka. The average recurrence intervals ranges between 3,5- and 5,3 ka with the last event taking place between the XIII and XVII centuries.