Facies control on seismites in an alluvial–aeolian system: The Pliocene dunefield of the Teruel half-graben basin (eastern Spain)

Abstract

The recognition of seismically induced soft-sediment deformation structures (SSDS) in sedimentary successions characterized by different facies, and hence by different rheology, is challenging. This is the case for high porosity and high permeability aeolian facies interbedded with muddy wet interdune deposits and alluvial conglomerates and sandstones. Several types of SSDS have been studied in two exposures of the Upper Pliocene (2.9-2.6 Ma) sediments of a fault-bounded intracontinental aeolian dune field in the Teruel Basin (Iberian Chain, eastern Spain). Among SSDS, load and fluid-escape structures, apart from several animal tracks, have been recognized. Those structures show an irregular distribution through the studied stratigraphic sections, being scarce in homogenous aeolian sands and frequent in water-related facies. A detailed study of the distribution and geometry of SSDS and their relationships with respect to the stratigraphic architecture and facies has allowed a critical discrimination of trigger mechanisms, i.e. biological or physical overloading vs. earthquakes. The seismically induced structures are concentrated into seven deformed beds, showing an uneven lateral distribution and geometry closely controlled by the hosting sedimentary facies and their rheology. These seismites resulted from liquefaction during moderate earthquakes (estimated magnitude from 5.0 to 6.8). The most probable seismogenic source was the Sierra del Pobo normal fault zone, located 2 km to the East. Results show how an appropriate recognition of sedimentary facies is crucial to understand the lateral variability of seismites in sedimentary environments characterized by sharp facies changes.

Alluvial sedimentation and tectono-stratigraphic evolution in a narrow extensional zigzag basin margin (northern Teruel Basin, Spain)

“…The study area is located in the northernmost sector of the basin (Fig. 1b), where the basin shows a halfgraben structure, with the eastern active boundary controlled by the N-S striking El Pobo extensional fault zone (Simón 1983;Moissenet 1983;Liesa 2011a, b;Rodríguez-López et al 2012;Liesa et al 2016) (Fig. 1c).…”

Earthquake‐induced soft‐sediment deformation structures from the Upper Triassic of the Jiyuan district, southern North China Craton: Implications for the Qinling Orogeny

“…High-magnitude earthquakes might be caused by glacial processes in a stable tectonic setting (van Loon et al, 2016), and soft-sediment deformation structures could be destroyed by later events. It is often difficult to observe soft-sediment deformation in thick, coarse sediments that have low lithological variation (Liesa et al, 2016). Regardless of these limitations, the above criteria are widely used to identify earthquake-triggered soft-sediment deformation structures (Mazumder et al, 2016;Põldsaar & Ainsaar, 2015;van Loon et al, 2016;Yang et al, 2015).…”

Controls on space–time distribution of soft-sediment deformation structures: Applying palaeomagnetic dating to approach the apparent recurrence period of paleoseisms at the Concud Fault (eastern Spain)

“…On the other hand, we should not forget that SSDSs distribution is also controlled by the observation scale and involved sedimentary facies (e.g., Alfaro et al, 1997;Rodríguez-López et al, 2007;Liesa et al, 2016), which can explain the scarcity of SSDSs in the western-…”