Caracterización geoquímica de las pizarras negras de las formaciones del Ordovícico Medio-Silúrico del sinclinal de Truchas.

  1. Ugidos Meana, José María
  2. Barba Regidor, Pedro
  3. Lombardero Barceló, Manuel

ISSN: 0213-683X

Year of publication: 2004

Issue: 36

Pages: 27-30

Type: Article

More publications in: Geogaceta


The contents of Ti02, Al2O3, P205, Rb, rare earth elements and Zr and some element ratios such as Al2O3/Ti02, Rb/Zr and Ti/Nb in black shales can be combined to discriminate among different Middle and Upper Ordovician formations in the La Cabrera region. Thus, the Casaio Fm. (lowermost Upper Ordovician) shows sharp chemical differences with the over-and-underlying formations. The Silurian black shales have negative cerium anomalies (Ce/Ce* = 0,82-0,92) probably related to the Silurian transgression. The lower Silurian beds also show variable and high contents (ppm) of Ba (636-3413), U (15-76), Mo (25-770), V (379-3747), Co (34-294) and Ni (54-797) with respect to all other black shales.