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 Volume 10 - Issue 1 (2012) |
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Stratigraphy and biostratigraphy (charophytes) of the marine-terrestrial transition in the Upper Eocene of the NE Ebro Basin (Catalonia, Spain)
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J. SANJUAN, C. MARTÍN-CLOSAS, J. SERRA-KIEL, H. GALLARDO |
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Abstract |
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The onset of endorheic sedimentation in the Ebro Basin is a prominent feature of the basin’s evolution and has
recently been characterized as a rapid event occurring in the Early Priabonian. In the north-eastern part of the
basin this event coincides with the deposition of the Artés Formation (Fm.), mainly built up by red beds of alluvial
origin. The marine-continental boundary has been poorly studied up to now in the so-called Lluçanès area, and
what was previously thought to be the base of the Artés Fm. is actually a transitional unit, which we define as the
Sant Boi Formation, which covers the underlying marine Milany Depositional Sequence and passes laterally to the
Terminal Complex, extending over 15km along the eastern margin of the Ebro Basin. The Sant Boi Fm. is formed
by up to 15-20m of alternating siltstones and lutite, grading upwards to brackish and lacustrine marls and lignite,
and represents deposition in a brackish to freshwater floodplain. It is characterized biostratigraphically by the
fossil charophyte assemblage Harrisichara lineata, Harrisichara vasiformis-tuberculata and Nodosochara jorbae,
from the middle part of the Priabonian. In contrast, the overlying red beds of the Artés Fm. are characterized by
assemblages containing Harrisichara tuberculata, Nodosochara jorbae and Lychnothamnus longus from the Late
Priabonian. These results are largely consistent with recent magnetostratigraphic studies performed south of the
studied area, and have enabled us to refine the stratigraphy of the marine-continental transition in the north-eastern
Ebro Basin. |
| Keywords:
Charophyta. Biostratigraphy. Ebro Basin. Eocene. Oligocene. |
| DOI:
10.1344/105.000001708
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Full text (PDF) |
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