In this work our purposes are (1) geochemical characterization of loess (‘primary loess’ or ‘true loess’ and ‘secondary loess’ or ‘loess-like deposits’) located in the centre of the Iberian Peninsula, (2) systematic study of element behaviour during pedogenesis and (3) evaluation of the suitability of using the geochemistry of loess to establish the average composition of these discontinuous aeolian sedimentary covers in central Spain. Several analyses were carried out on the bulk sample and on the sandy and clay fractions (mineralogical composition by X-ray diffraction, mineralogical studies of heavy minerals by petrographical microscopy and chemical composition by flame atomic absorption spectrometry). Loess from the Spanish central region has a local origin. The presence of gypsum in the ‘loess-like’ deposits reaches values two times higher than in ‘true loess’, and ‘true loess’ has a higher concentration of quartz, calcite and kaolinite. Regarding chemical composition, similar concentrations of Ca, K, Mg and Na were found, although it is important to note the higher concentration of Na in some of the samples.

A new occurrence of the Hirnantia brachiopod fauna is documented from the Criadero Quartzite of Almadén, Ciudad Real Province, Spain. This unit is the regional development of a largely unfossiliferous sandy facies that frequently overlies the typical Late Ordovician diamictitic glaciomarine formations in the Iberian Peninsula and the Armorican Massif. The new occurrence establishes palaeontologically the latest Ashgill age of the quartzite, at least for its lowest horizons, and adds new data on a fauna that, although widespread, has been very rarely documented from peri-Gondwanan Europe. The new collection contains only Hirnantia sagittifera and Plectothyrella crassicosta chauveli. The subspecific status of the latter and its inclusion within Plectothyrella crassicosta is discussed herein, based on the continuous variation in rib thickness of several samples of both forms. The extremely low diversity and the occurrence of the key form P. c. chauveli, are both typical of the Bani Province that developed on the subpolar margins of Gondwana. This contrasts with other occurrences of the Hirnantia Fauna in peri-Gondwanan Europe, such as those from Sardinia and the Carnic Alps, which are characteristic of the more temperate Kosov Province.