10 Myr evolution of sedimentation rates in a deep marine to non‐marine foreland basin system: Tectonic and sedimentary controls (Eocene, Tremp–Jaca Basin, Southern Pyrenees, NE Spain)

Abstract

The propagation of the deformation front in foreland systems is typically accompanied by the incorporation of parts of the basin into wedge‐top piggy‐back basins, this process is likely producing considerable changes to sedimentation rates (SR). Here we investigate the spatial‐temporal evolution of SR for the Tremp–Jaca Basin in the Southern Pyrenees during its evolution from a wedge‐top, foreredeep, forebulge configuration to a wedge‐top stage. SR were controlled by a series of tectonic structures that influenced subsidence distribution and modified the sediment dispersal patterns. We compare the decompacted SR calculated from 12 magnetostratigraphic sections located throughout the Tremp–Jaca Basin represent the full range of depositional environment and times. While the derived long‐term SR range between 9.0 and 84.5 cm/kyr, compiled data at the scale of magnetozones (0.1–2.5 Myr) yield SR that range from 3.0 to 170 cm/kyr. From this analysis, three main types of depocenter are recognized: a regional depocenter in the foredeep depozone; depocenters related to both regional subsidence and salt tectonics in the wedge‐top depozone; and a depocenter related to clastic shelf building showing transgressive and regressive trends with graded and non‐graded episodes. From the evolution of SR we distinguish two stages. The Lutetian Stage (from 49.1–41.2 Ma) portrays a compartmentalized basin characterized by variable SR in dominantly underfilled accommodation areas. The markedly different advance of the deformation front between the Central and Western Pyrenees resulted in a complex distribution of the foreland depozones during this stage. The Bartonian–Priabonian Stage (41.2–36.9 Ma) represents the integration of the whole basin into the wedge‐top, showing a generalized reduction of SR in a mostly overfilled relatively uniform basin. The stacking of basement units in the hinterland during the whole period produced unusually high SR in the wedge‐top depozone.

Paleogeographic and sedimentary evolution of the South Pyrenean foreland basin

“…The first developed in the Jaca basin between the Paloecene carbonate platforms and their 165 overlying deep marine deposits of the Hecho Group. The corresponding hiatus could result from 166 a combination of processes such as forebulge development, starvation following drowning of the 167 platforms, and instabilization and collapse of the out-of-grade platform margins (Payros et al, 168 1999b;Vinyoles et al, 2019). The second erosional episode developed in the Tremp-Graus basin 169 during the Lutetian.…”

Fluvio-deltaic record of increased sediment transport during the Middle Eocene Climatic Optimum (MECO), Southern Pyrenees, Spain

“…The successions are characterized by excellent exposure and have already been dated thanks to high-resolution magnetostratigraphy. Both sections reveal progradation of deltaic and fluvial systems coeval with the magnetic reversal occurring at chrons C18r and C18n.2n, near or at the zenith of MECO warmth (Edgar et al, 2010(Edgar et al, , 2020Garcés et al, 2014;Vinyoles et al, 2021). We generated new high-resolution profiles of ẟ 13 C and ẟ 18 O, XRF, clays, and Rock Eval, across the Chron C18r-C18n.2n reversal, in order to identify geochemical changes associated with the MECO onset and its recovery and test the possible causative links between progradation and the MECO perturbation.…”

“…Shallow marine environments are mainly dominated by marly facies, which thanks to their high carbonate content and the relatively deep depositional environment are suitable for geochemical purposes (Wendler, 2013). Available high-resolution magnetostratigraphy in the Pyrenean region provides a correlation of different sections along the entire source-to-sink system (Vinyoles et al, 2021). We selected two lower Bartonian sections, Belsué (BS) and Yebra de Basa (YB), because they present excellent exposition and are provided with magnetostratigraphic dating, aiming to unravel the geochemical history of the two main deltaic systems coeval to the MECO.…”

“…It is composed of three subsections covering the lower Bartonian interval (Fig. 3), between the upper part of the chron C18r and the chron C18n.1r (Vinyoles et al, 2021). The first subsection is located west (Yb-C), within the Larrés marls, whose top is correlated with the base of the Vinyoles et al, (2021)…”

Magnetostratigraphy and stable isotope stratigraphy of the middle-Eocene succession of the Ainsa basin (Spain): new age constraints and implications for sediment delivery to the deep waters

“…The last stage of the development of the South-Central Pyrenean Unit is characterized by a decrease in subsidence rates due to the southward migration of the deformation and a general progradation induced by the development of the Pyrenean Axial Zone antiformal stack (Muñoz, 1992;Sinclair et al, 2005). From the upper Eocene to the Oligocene, successively shallow marine (Sobrarbe deltaic complex, Bartonian stage, Dreyer et al, 1999;Mochales et al, 2012a; and continental fluvial sediments (Escanilla Formation, Bentham et al, 1992;Michael et al, 2014, Vinyoles et al, 2019 were deposited in the basins. During the late Priabonian, the Tremp-Graus-Ainsa-Jaca basins were disconnected from the Atlantic sea, most probably as a consequence of the emplacement of the Basque-Cantabrian units in the west (Costa et al, 2010).…”