Geology Reference
In-Depth Information
were applied to interpret analogous deposits in the
Spanish Pyrenees (Donselaar and Nio
1982
; Yang and
Nio
1985,
1989
). The tidal nature of the deposits was
recognized early on, but the larger environmental setting
remains the subject of discussion and re-evaluation.
The tide-infl uenced and tide-dominated successions
discussed in this chapter form part of a number of forma-
tions of Ypresian and Lutetian age covering a continuum
of almost 16 Ma. Tidal deposits of Maastrichtian age
in the Aren Formation (Tremp Group; Nagtegaal et al.
1983
; De Boer
1985
, and a wealth of recent but unpub-
lished data collected by Spanish workers) and of Upper
Lutetian age in the Sobrarbe Formation (Campodarbe
Group; Hall
1997
; Dreyer et al.
1999
) are also present
but are not included in this chapter.
This chapter discusses examples of two different
styles of tidal amplifi cation that existed during the
Ypresian and Lutetian in the central Pyrenean thrust-
sheet-top Tremp-Graus-Ager Basin. The fi rst style was
controlled by the underfi lled foredeep stage of basin
development, the second style by the overfi lled shelf
stage of basin development. The two styles were
closely related to signifi cant differences in basin con-
fi guration characteristics and controlled by thrust-
sheet-top basin (cf. DeCelles and Giles
1996
)
development and associated changes in basin paleo-
geography, morphology and dimensions. Therefore,
usage of the terms foredeep and shelf in this chapter is
strictly related to the particular development of the
thrust-sheet-top basin as outlined hereafter. In addi-
tion, eustatic sea-level fl uctuations infl uenced the
degree of tidal amplifi cation. A summary of the char-
acteristics of the two styles is given in Table
18.1
and
discussed hereafter.
(the south Pyrenean central unit of Séguret
1972
) .
For details about other aspects of structural evolution
of the Pyrenees, one is referred to Van der Voo (
1969
) ,
Puigdefàbregas and Souquet (
1986
) , Galdeano et al.
(
1989
) , Malot (
1989
) , Choukroune et al. (
1990
) ,
Malod and Mauffret (
1990
) , Srivastava et al. (
1990
) ,
Roest and Srivastava (
1991
) , Olivet (
1996
) , Meigs and
Burbank (
1997
), and Capote et al. (
2002
) .
An important phase in the development of the
Pyrenees started around 84 Ma (Late Santonian) when
the Iberian Plate and the African Plate collided,
and subduction along the northern plate margin was
initiated (Guimerá
1984,
1996
) . This caused conver-
sion from a foregoing extension phase to compression
with a near N-S shortening direction, and produced
inversion of Mesozoic extensional rift basins and the
rise of the Pyrenees (Beaumont et al.
2000
; Capote
et al.
2002
) .
Two main foreland basins, the Aquitanian basin in
the north and the Pyrenean Foreland basin to the south,
developed from the Late Santonian (84 Ma) to the
Miocene in conjunction with the convergence from
extension to compression (Cámara and Klimowitz
1985
; Puigdefàbregas et al.
1992
; Teixell and Muñoz
2000
; Beaumont et al.
2000
) . Four main compressional
stages are recognized in the Pyrenean Foreland Basin
(Puigdefàbregas et al.
1992
) of which Stage III is the
focus of this chapter.
Three main thrusts developed during Stage III
(Early and Middle Eocene): from north to south the
Bóixols, Montsec and Sierras Marginales. They were
initiated successively in time but their displacement
periods overlapped; they are particularly clear in the
ECORS seismic profi le (Cámara and Klimowitz
1985
; Choukroune et al.
1989,
1990
; Figs.
18.1
and
18.2
). In the central Pyrenees, the size and shape of
the thrust sheets were determined by the inverted
Mesozoic fault pattern which controlled the location
of oblique (with respect to the thrust motion) and lat-
eral ramps that are defi ned as dividing two different
segments of a thrust belt and consequently the distri-
bution of accommodation space and thrust-sheet-top
basin facies (Puigdefàbregas et al.
1992
;
18.2
Geological Framework
18.2.1 Development of Lower Eocene
Thrust-Sheet-Top Basins
The Pyrenean Range (Capote et al.
2002
) consists
of the Aragonese-Catalan Pyrenees in the east and
the Basque-Cantabrian Pyrenees in the west. The
Aragonese-Catalan Pyrenees are subdivided into the
Eastern, Central and West-Central Pyrenees (Fig.
18.1
).
The focus in this chapter will be exclusively on the
thrust-sheet-top basins of the Spanish Central Pyrenees
Vergés
2007
) .
Initiation of the Montsec Thrust occurred at the
end of the Paleocene (Cámara and Klimowitz
1985
;
Puigdefàbregas et al.
1986,
1992
; Nijman
1998
; Mascle
and Puigdefàbregas
1998
) . The thrust underlies more
