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Location of the Gabardiella section and main geological features of the area of study: A. Geologic map of the Southwestern Pyrenees. Highlighted rectangle: Jaca basin, External Sierras and Ebro Basin (from North to South). B. Geological cross-section (from Casas and Pardo, 2004). The red point shows the location of the Gabardiella section. It can be seen that the involved rocks are structurally located on the External Sierras frontal thrust.
Source publication
In this paper we present new magnetostratigraphic data performed in the lower part of the Gabardiella section. Sixty-three levels were sampled in 218 m with the aim to determine the Cuisian- Lutetian boundary at this location. Despite the limited quality of the data, we observe normal and reverse primary directions with a mean of (n, D, I, Alfa95 &...
Context in source publication
Context 1
... to the Boltaña formation of Barnolas et al. (1991) (Samsó et al., 2014, with appearances of alveolines (SBZ11). Over them, a thick group of limestones (660m), represents the Guara formation of Puigdefábregas (1975), in the sense of Samsó et al. (1994); Rodríguez-Pintó et al. (2012). The marls of Arguis formation show up at the top of the section (Fig. ...
Citations
... To the west, the pioneer work by Hogan and Burbank (1996) from the top of the Guara Fm. to the top of the molassic Campodarbe and Bernués fms. were later on totally reviewed along the Cusian-Lutetian boundary (Gabardiella section; Rodríguez-Pintó et al., 2017), the Lutetian carbonate platform Guara Fm. (Isuela section by Rodríguez-Pintó et al., 2012a and other western sections by Silva-Casal et al., 2019, see overview in Silva-Casal et al., 2021, the Bartonian prodeltaic marls of the Arguis Fm. (Kodama et al., 2010) and the transitional deposits of the Belsué Fm. (Garcés et al., 2014;. Additionally, the marine platform deposits in the southern sector of the Balzes anticline are also dated in the San Pelegrin section (Rodríguez-Pintó et al., 2013a). ...
Despite the large number of magnetostratigraphic studies in the South Pyrenean Basin aiming to calibrate the basin chronostratigraphy and the biostratigraphic scales, the South Eastern Jaca Basin remains unexplored from this perspective, and its relation with the Ainsa Basin is not fully understood. In this work we contribute with new magnetostratigraphic data from the 950m thick Las Bellostas section, located in the northern hinge of the Balzes anticline. Well-proven primary signal (positive fold test and two pseudo-antiparallel polarities) supported by numerous primary data in the surroundings allow us building a reliable local polarity sequence of eight magnetozones (from R1 to N4). Additionally, seven new biostratigraphic samples (Nummulites and Assilina) in the lower part of the section (marine environment) allows tightening the section to the Geomagnetic Polarity Time Scale (GPTS) and proposing a refined age model for the southeastern Jaca Basin. The section starts in the Boltaña Fm., of Cuisian age (Shallow Benthic Zone, SBZ11), is followed by a sedimentary gap from C22n to C20n as witnessed by biostratigraphic data (SBZ11 underneath the hiatus and SBZ16 just atop). The deltaic Sobrarbe Fm can be tracked until the C19n (Late Lutetian). From this point (200m) until the top of the section (950m), at least, the entire C18n chron can be recognized within the molassic Campodarbe Fm (C18n.2n-C18n.1r and C18n.1n) (Bartonian) equivalent to the West to the prodeltaic Arguis marls Fm. The Middle Cusian (SBZ11) to Middle Lutetian (SBZ15) stratigraphic hiatus is, in part, enhanced by the structural position at the hinge of the Balzes anticline. These new chronostratigraphic constraints help refining the WE and N-S stratigraphic relationships in the eastern Jaca Basin and in the Ainsa Basin. This section also allows us to accurately refine the kinematics of the rotational activity in the eastern External Sierras. The significant difference in magnetic declination along the section and neighboring paleomagnetic data from the Balzes anticline (from ≈70º clockwise at the base of the stratigraphic section to non-significant at the top) together with the new age model for the Eastern Jaca Basin help characterizing the rotational activity of the Balzes thrust sheet. The rotation took place between chrons C20r (Middle Lutetian; 45Ma) and C17 (Lower Priabonian 37-38Ma) in agreement to nearby structures (Boltaña, Pico del Aguila anticlines) but clearly diachronic to western ones (Santo Domingo anticline). Besides, the rotational A B S T R A C T
... Data from western Pyrenees (Gorrondatxe and Otsakar sections) (Molina et al., 2011;Orue-Etxebarria et al., 2006;Payros et al., 2007Payros et al., , 2011, only provide shelf derived larger foraminifera in resedimented beds, with a significant lack of larger foraminiferal data toward the Y/L transition. In the shallow carbonate platform and slope transitions of the South Pyrenean foreland margin (San Pelegrin and Ainsa Basin around the Boltaña anticline) (Mochales et al., 2012;Rodríguez-Pintó et al., 2013), as well as in the Gabardiella section to the West (Rodríguez-Pintó et al., 2017), the Y/L transition is hampered by stratigraphic gaps. Conversely, the Ésera valley section displays a thick shallow marine succession that includes the Ypresian/Lutetian transition, rich in larger foraminifera (Payros et al., 2009b;Schaub, 1966Schaub, , 1973Schaub, , 1981Schaub, , 1992Tosquella, 1995;Tosquella and Serra-Kiel, 1998). ...
An integrated study including magnetostratigraphy, larger benthic foraminifera and calcareous nannofossil biostratigraphy is presented herein. This work was performed in shallow marine siliciclastics rich in larger foraminifera, around the Ypresian/Lutetian boundary in the Ésera valley (South-Central Pyrenees). Although the calcareous nannofossil content in the studied interval is low, not allowing a precise Y/L boundary to be recognised, the taxa found are enough to support the chronostratigraphic attribution.
Data obtained in the Ésera valley section has improved the knowledge of larger benthic foraminifera (Nummulites and Assilina) distribution through chron C21. SBZ 11 to SBZ 12 transition took place at the lowermost C21r, as shown in previous works. SBZ 12 assemblages extend into C21n, where the SBZ 12 to SBZ 13 boundary occurs. These data, obtained in shallow marine siliciclastic facies, with in situ fauna, results in a shift of the SBZ 12/SBZ 13 boundary to the Lower Lutetian, younger than previously believed. Accordingly, the Ypresian/Lutetian boundary occurs in SBZ 12.
... The limestones contain abundant porcellaneous foraminifera (Alveolina, Idalina) and conical agglutinated forms (Coskinolina). In the study area, this unit has been attributed to the late Ypresian (Cuisian) SBZ11 (Rodríguez-Pintó et al., 2012a) and correlated to magnetic polarity Chron C22r (Rodríguez-Pintó et al., 2017). The thicker Ara River section in the east, at the core of the Boltaña anticline spans from the upper part of chron C24n to chron C22r (Mochales et al., 2012). ...
... The calibration of the biostratigraphic data of this study with magnetostratigraphic data (Rodríguez-Pintó et al., 2012a, b;Rodríguez-Pintó et al., 2017;Silva-Casal et al., 2019) allowed the correlation of the late Ypresian-lower Bartonian shallow marine succesions (i.e. Boltaña, Guara and Arguis formations) throughout the central (Fig. 31) and western parts (Fig. 32) of the Sierras Exteriores. ...
An extense systematic description of the Eocene larger foraminiferal faunas recorded in the South Pyrenean Basin (Sierras Exteriores) is presented herein. The large dataset provided in this work includes both Nummulites and Alveolina species, along with a variety of other porcellaneous and hyaline taxa with lesser biostratigraphic relevance, are represented. The larger foraminifera described in this work correspond mainly to the Lutetian (SBZ13 to SBZ16 biozones) interval, but late Ypresian (SBZ11, Cuisian) and Bartonian (SBZ17) shallow benthic zones have also been identified.As one of the most relevant results of this systematic analysis, a new species, Idalina osquetaensis, is described. The systematic revision of middle to late Lutetian alveolines led to a reassessment of A. fusiformis and the finding of two new precursor forms, described as affinis of their corresponding species, A. aff. fragilis and A. aff. elongata. The new forms A. aff. elongata and A. aff. fragilis fill the gap in the middle to late Lutetian alveolinid biostratigraphy. Despite not being exclusive to SBZ16, these new forms provide realiable biostratigraphic information where Nummulites are not present. This realibility lies on the correlation of Nummulites and Alveolina biomarkers in the same sections and their calibration to the global time scale through magnetostratigraphy. In fact, magnetostratigraphic calibration of all described taxa is also provided, along with an update of the SBZ calibration to the current Geologic Time Scale (Gradstein et al., 2012).
