Abstract
The Cenomanian to early Santonian interval is usually considered a time of postrifting tectonic quiescence around the northern margins of Iberia that preceded the onset of the Pyrenean convergence by crustal thrusting in the latest Santonian. However, plate kinematic models of the Mesozoic evolution of Iberia poorly constrain the Turonian-Santonian position of Iberia relative to Eurasia. This study reconstructs changes in the sedimentary facies and architecture of the Iberian carbonate platform throughout the Late Cretaceous and sheds new light on the geodynamic evolution of the Iberia-Eurasia relationship at that time. Sixteen outcrop sections were described and 24 sedimentary facies identified that define 5 depositional environments ranging from the deep marine basin to the continental setting. From these and previously published field data we reconstruct the evolution of the Pyrenean carbonate platform, on an east-west transect nearly 400 km long, on the basis of 11 short-term depositional sequences and 5 long-term hemicycles. In our interpretation, the Cenomanian and Turonian correspond to a postrift stage during which the European and Iberian margins, together with the deep basin between them, subside gently, as shown by accommodation rates varying from ∼15 to 30 m/My in the margins and ∼100 to 150 m/My in the basin. The Coniacian and early Santonian are characterized by a large-scale flexural response consisting of (1) uplift of the southern Iberian margin, with negative accommodation rates, karstified surfaces and paleosols, and (2) increasing subsidence rates in the basin and its edges (the northern Iberian margin and eastern Aquitaine platform), with accommodation rates several times greater than during the Turonian. We propose that far-field stress possibly related to the northeastward motion of Africa, and/or onset of shortening at the Iberia-Europe boundary in the central and eastern Pyrenees led to the incipient large-scale flexural deformation in the Pyrenean domain. The late Santonian and Campanian are an early orogenic stage marked by rapid subsidence throughout the Pyrenean domain, except at its western end. We evidence for the first time a pre-orogenic flexure at the Iberia-Europe plate boundary induced by regional plate reorganisation between Africa and Europe during the Coniacian and the early Santonian.
Highlights
IntroductionThe Late Cretaceous tectonic history in the vicinity of the boundary between the Iberian and European plates is usually considered in terms of three stages: (1) an Albian to early Cenomanian rifting stage, leading to the hyperextension of continental crust and local exhumation of subcontinental mantle at the basin floor (Jammes et al, 2009; Lagabrielle et al, 2010; Masini et al, 2014; Teixell et al, 2016), (2) a midCenomanian to mid-Santonian quiescent stage associated with postrift subsidence on both the north Iberian and south European margins, and (3) the onset of Pyrenean convergence at the end of the Santonian, based in particular on the earliest evidence of crustal thrusting (Puigdefàbregas and Souquet, 1986; Puigdefàbregas et al, 1992; Olivet, 1996; Srivastava et al, 2000; Rosenbaum et al, 2002; Sibuet et al, 2004; Jammes et al, 2009; Handy et al, 2010; Vissers and Meijer, 2012; Mouthereau et al, 2014; Macchiavelli et al, 2017)
The Cenomanian to early Santonian interval is usually considered a time of postrifting tectonic quiescence around the northern margins of Iberia that preceded the onset of the Pyrenean convergence by crustal thrusting in the latest Santonian
The facies were grouped into five positions within the downdip profile: the slope to basin for facies deposited in deep marine environments, the outer ramp for facies deposited below the storm wave base on the platform (F2, four facies), the mid-ramp for facies deposited between the storm wave base and the fair-weather wave base (F3, five facies), the shoal/barrier environments in the inner ramp for wave- and tide-dominated facies deposited above the fairweather wave base (F4, six facies), and lagoon to continental environments for facies deposited in calm and shallow environments, or continental environments above high tides (F5, seven facies)
Summary
The Late Cretaceous tectonic history in the vicinity of the boundary between the Iberian and European plates is usually considered in terms of three stages: (1) an Albian to early Cenomanian rifting stage, leading to the hyperextension of continental crust and local exhumation of subcontinental mantle at the basin floor (Jammes et al, 2009; Lagabrielle et al, 2010; Masini et al, 2014; Teixell et al, 2016), (2) a midCenomanian to mid-Santonian quiescent stage associated with postrift subsidence on both the north Iberian and south European margins, and (3) the onset of Pyrenean convergence at the end of the Santonian, based in particular on the earliest evidence of crustal thrusting (Puigdefàbregas and Souquet, 1986; Puigdefàbregas et al, 1992; Olivet, 1996; Srivastava et al, 2000; Rosenbaum et al, 2002; Sibuet et al, 2004; Jammes et al, 2009; Handy et al, 2010; Vissers and Meijer, 2012; Mouthereau et al, 2014; Macchiavelli et al, 2017). Modeling the Mesozoic plate kinematic evolution of Iberia —based on seafloor magnetic anomalies, paleomagnetic studies and geophysical and geological data—has been the subject of increasing debate in recent decades (e.g., Olivet, 1996; Vissers and Meijer, 2012; Neres et al, 2013; BarnettMoore et al, 2016). Paleomagnetic data for the Late Cretaceous are especially scarce and have high uncertainties, for the early
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