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Morphological Abnormalities and Dwarfism in Maastrichtian Foraminifera from the Cárdenas Formation, Valles–San Luis Potosí Platform, Mexico: evidence of paleoenvironmental stress

Omaña, Lourdes ; Alencáster, Gloria ; Hernández, José Ramón Torres ; Doncel, Rubén López

Boletín de la Sociedad Geológica Mexicana, 2012-01, Vol.64 (3), p.305-318

Sociedad Geológica Mexicana e Instituto de Geología de la UNAM

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  • Título:
    Morphological Abnormalities and Dwarfism in Maastrichtian Foraminifera from the Cárdenas Formation, Valles–San Luis Potosí Platform, Mexico: evidence of paleoenvironmental stress
  • Autor: Omaña, Lourdes ; Alencáster, Gloria ; Hernández, José Ramón Torres ; Doncel, Rubén López
  • Assuntos: ARTÍCULOS ; Carbonates ; Climate change ; Dwarfism ; Geology ; Geosciences, Multidisciplinary ; Maastrichtian age ; Mathematical minima ; Micropaleontology ; Paleoecology ; Specimens ; Tectonics
  • É parte de: Boletín de la Sociedad Geológica Mexicana, 2012-01, Vol.64 (3), p.305-318
  • Descrição: During the early Maastrichtian an assemblage rich in large foraminifera, mostly composed of orbitoidal foraminifera, developed in the shallow-water deposits of the Cárdenas Formation (Valles–San Luis Potosí Platform, Mexico). Among them, the most abundant isLepidorbitoides minima, some of which display a morphologically abnormal test consisting of polyvalent forms, conical tests and budding, which could be induced by abrupt changes in environmental factors. The occurrence of the abnormalities preceded the demise of this species and of all the larger foraminiferal association in the upper part of theGansserina gansseriZone (early Maastrichtian). The abnormalities could be induced by environmental stress, probably related to interplay of different events such as increased terrigenous input and the transition to deeper facies due to Laramide tectonic instability before the K/P boundary. A late Maastrichtian community of dwarfed planktic foraminifera composed ofTrinitella scottiBrönnimann,Plummerita reicheliBrönnimann,Rugoglobigerinacf.macrocephalaBrönnimann,Rugoglobigerina hexacamerataBrönnimann,Heterohelix punctulata(Cushman),Pseudoguembelina costulata(Cushman),Pseudotextularia intermediade Klasz,Globigerinelloides asperusBolli,Guembelitria cretaceaCushman,Rugoglobigerina rugosa(Plummer),Rugotruncana sp.,Globotruncanita stuarti(de Lapparent), andGlobotruncana arca(Cushman) developed in the upper part of the sequence. This uncommon morphology could also be related to the highly stressed paleoenvironmental conditions related to global climatic change and local tectonic activity. Associated with this planktic assemblage is a deeper-water dwarfed benthic foraminiferal community composed ofGyroidinoides nitidus(Reuss),Coryphostoma incrassata(Reuss),Pseudouvigerina plummeraeCushman,P. cretaceaCushman,Bolivina cretosaCushman,Planulina texanaCushman andCibicides harperi(Sandidge).
  • Editor: Sociedad Geológica Mexicana e Instituto de Geología de la UNAM
  • Idioma: Inglês;Português
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