Abstract
A review of the stratigraphy of the Galve sub-basin (western Maestrazgo Basin, eastern Spain) around the Jurassic–Cretaceous transition is presented here, based on new data acquired after extensive geological mapping and logging complemented with facies analysis, new biostratigraphic data and a revision of the published information available. The results obtained are relevant for a more detailed understanding of the tecto-sedimentary evolution of the studied basin during the transition between two stages of rift evolution (i.e., syn-rift sequences 1 and 2). In addition, new information on the age and setting of numerous dinosaur fossil- and track-sites found across the Galve sub-basin and in the northern part of the nearby Penyagolosa sub-basin is provided here. Two new lithostratigraphic units are defined and characterized, the Aguilar del Alfambra and the Galve formations. The previous stratigraphic framework considered only two lithostratigraphic units (the Villar del Arzobispo and El Castellar formations) bounded by a single regional unconformity, and this resulted in significant misinterpretations. The whitish limestones, red lutites and cross-bedded sandstones of the Aguilar del Alfambra Formation were deposited in transitional environments, ranging from coastal lutitic plains to restricted lagoons. Of particular interest are the laminated micritic-peloidal limestones with abundant fenestral porosity (supratidal ponds to intertidal flats), which preserve common dinosaur footprints. This unit is bounded by widespread unconformities and is of very variable thickness (0–450 m), controlled by extensional tectonics operating at the climax of syn-rift sequence 1 during the latest Tithonian–middle Berriasian. The overlying Galve Formation is of variable thickness (from 0 to 100 m) and is also bounded by regional unconformities described in detail here. It consists of red lutites with cross-bedded and tabular-burrowed sandstones representing channel and overflow deposits in an alluvial floodplain. The sauropod dinosaur Aragosaurus ischiaticus found in this unit has a controversial age assignment. The age of the Galve Formation is poorly constrained from late Berriasian to Hauterivian, but new biostratigraphic data presented here, combined with the correlation with the nearby Penyagolosa and Salzedella sub-basins, suggest a possible equivalence to the upper Berriasian–lower Valanginian sequence deposited during the initial stage of syn-rift sequence 2.
Highlights
The Iberian Rift System of eastern Spain formed part of the network of rifted basins that evolved on the northwestern Peri-Tethyan Platform during the break-up of Pangaea, and the opening of the Alpine Tethys and the North Atlantic
We report on a revised stratigraphic framework, facies analysis and new biostratigraphic data, which allow a more complete understanding of the age and palaeoenvironmental setting of the numerous dinosaur fossil- and track sites found across the Galve sub-basin (e.g., Ruiz-Omeñaca et al, 2004)
A relevant example to illustrate these problems is provided by the discussion on the stratigraphic position and age of the first dinosaur to be described in Spain, the sauropod Aragosaurus ischiaticus Sanz, Buscalioni, Casanovas, Santafé, 1987 (Fig. 1)
Summary
The Iberian Rift System of eastern Spain formed part of the network of rifted basins that evolved on the northwestern Peri-Tethyan Platform during the break-up of Pangaea, and the opening of the Alpine Tethys and the North Atlantic. The main objective of this work is to review the stratigraphy and tecto-sedimentary evolution of the western part of the Maestrazgo Basin (i.e., the Galve sub-basin) around the Jurassic-Cretaceous transition. In Galve (the municipality where Aragosaurus was recovered), Diaz-Molina and Yébenes (1987) differentiated five lithostratigraphic units (units 1–5), bounded by significant sedimentary discontinuities. Unit 2 was developed around the Jurassic-Cretaceous transition, as indicated by the presence of the large benthic foraminifer Anchispirocyclina lusitanica. This unit was subsequently assigned to the Villar del Arzobispo Formation (e.g., Aurell & Meléndez, 1993). Later on, Soria (1997) proposed that Units 3 and 4 would correspond to the upper Hauterivian–lower Barremian alluvial-lacustrine system represented by the lower and upper parts of the El Castellar Formation, respectively
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