Sequence stratigraphy in continental endorheic basins. New contributions from the case of the northern extensional Teruel

Abstract

The tectono-sedimentary analysis is a sequence stratigraphy method particularly useful in continental tectonically active basins far from the influence of sea level changes. It provides a comprehensive study of the sedimentary features and stratigraphic architecture of a basin focusing on the stratigraphical, mainly cyclic, trend of the rock record in order to define genetic (tectono-sedimentary units-TSUs) controlled by allocyclic factors:, tectonics and climate. The tectono-sedimentary analysis has been traditionally used in basins related to compressive stress regimes, but their application in extensional basins is less common. In this work the results of the detailed tectono-sedimentary analysis of the northern Teruel Basin rocks are presented. Vertical and lateral distribution of mappable lithofacies associations reveal different depositional systems laterally related and the main paleogeographic changes from the Late Miocene to Early Gelasian (11–1.8 Myr). Five main alluvial progradational-retrogradational cycles integrate six TSUs with chronostratigraphical meaning, bounded by isochronous stratigraphic surfaces (sedimentary breaks) that represent maximum alluvial progradations, and define the basin geodynamic framework. A main challenge, not commonly addressed in this kind of studies, is the discrimination of the effects of tectonic and climate for each unit, which has been based on evidences of synsedimentary tectonism in combination with δ18OPDB isotope data. It is demonstrated that the sedimentary evolution was mainly controlled by the tectonics, with the phases of tectonic activity being consistently recorded as alluvial progradations (correlative lacustrine retractions) and climate only modulating (amplifying or vanishing) the tectonic effects. Certain guidelines are proposed to adequately recognize and characterize genetic units in continental extensional basins. Our results reinforce TSUs as very valuable tools for studying active continental basins far from sea level effects and to discriminate the influence of allogenic controls in sedimentation.