'Autochthonous' bivalve assemblages and palaeoecologic interpretation in the upper Jurassic-Lowermost Cretaceous La Caja Formation from the Canon de San Matias (Zacatecas, Mexico)
A. De La Mora et al., 'Autochthonous' bivalve assemblages and palaeoecologic interpretation in the upper Jurassic-Lowermost Cretaceous La Caja Formation from the Canon de San Matias (Zacatecas, Mexico), CR AC S IIA, 331(11), 2000, pp. 741-747
Citations number
30
Categorie Soggetti
Earth Sciences
Journal title
COMPTES RENDUS DE L ACADEMIE DES SCIENCES SERIE II FASCICULE A-SCIENCES DELA TERRE ET DES PLANETES
The present research approaches the precise palaeoecologic interpretation b
ased on the recognition of 12 'autochthonous' bivalve assemblages among 52
registered from the Upper Jurassic-Lowermost Cretaceous La Caja Formation i
n the Canon de San Matias section (Mexican Altiplano). Fine-grained deposit
s together with the near-exclusive record of suspension-feeders are conside
red the evidence for low-energy and nutrient-rich environments. The presenc
e of oxygen-dependent bivalves, mainly Buchia and Lucina, supports the inte
rpretation of oxygenation as a major factor controlling ecology and therefo
re the composition of the 'autochthonous' bivalve assemblages studied. Sign
ificant changes in the composition of bivalve assemblages show no relation
between fluctuations in ecological factors and background depositional cond
itions. (C) 2000 Academie des sciences / Editions scientifiques et medicate
s Elsevier SAS.