El Jurásico Superior en el sector noroccidental de la Península Ibérica (España): bioestratigrafía y principales grupos de bivalvos.

Content Provider	Semantic Scholar
Author	Delvene, Graciela Pérez-Urresti, I. Meléndez, Guillermo
Copyright Year	2011
Abstract	Upper Jurassic (upper Oxfordian to lower Kimmeridgian) deposits in the North-western Iberian Range (Aragonese Branch) around the locality of Ricla (Zaragoza) form a thick carbonate and terrigenous marly section showing an increasing content in siliciclastic components. The studied sequence corresponds to the Upper Jurassic Aldealpozo and Sot de Chera Fm. It has been recorded in detail in outcrops Ri4 and Ri8, some 5 to 10 km North from the village of Ricla. Three lithologic intervals are distinguished: an interval formed by silty to slightly sandy limestones (Aldealpozo Fm); and two intervals of the Sot de Chera Fm, a lower one formed by marls, and an upper one, more siliciclastic and rich in bivalves. The scarce ammonite associations recorded significantly improve the biostratigraphic data, allowing delineate approximately the zone boundaries, from upper Oxfordian Bimammatum Biozone to lower Kimmeridgian (?) Platynota Biozone. The Bimammatum and Hauffianum biozones are represented in the lower, silty to slightly sandy limestone interval (Aldealpozo Fm). The Planula biozone is represented in the marly interval of the Sot de Chera Fm. The former latest Oxfordian Galar Subbiozone, now to be proposed as the basal biozone of the lower Kimmeridgian, is widely developed in the upper part of the sequence. This allows placing the Oxfordian-Kimmeridgian stage boundary roughly coinciding with the lithological transition between both intervals of the Sot de Chera Fm. An updated biostratigraphic scale is, hence, presented according to the recent trends within the Jurasssic Sucommission (ICS; IUGS) about the position of the Oxfordian-Kimmeridgian stage boundary. Bivalve associations in turn are rich and diversified, and their detail study supplies consistent information to reconstruct sedimentary environmental changes. The analysed assemblage comprises a whole of 2.002 specimens distributed in 47 species and belonging to 32 genera and subgenera. They correspond to the subclasses Palaeotaxodonta (4%), Pteriomorphia (64,6%), Palaeoheterodonta (0,5%), Heterodonta (29,9%) and Anomalodesmata (1%). The most abundant species are Nanogyra nana (J. Sowerby 1822) and Nicaniella ( Trautscholdia ) carinata (Phillips 1829).
Starting Page	63
Ending Page	76
Page Count	14
File Format	PDF HTM / HTML
Volume Number	22
Alternate Webpage(s)	http://www.sepaleontologia.es/revista/anteriores/REP%20(2007)%20vol.%2022/1/02.%20Delvene%20et%20al.pdf
Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article