Multi-aged social behaviour based on artiodactyl tracks in an early Miocene palustrine wetland (Ebro Basin, Spain).

We present a new locality with at least 880 vertebrate tracks found at the top of a limestone bed from the lower Miocene Tudela Formation (Spain). The trampled surface was formed by artiodactyls that crossed a muddy carbonate accumulated under the influence of water level variations in a palustrine environment. The tracks reflect different types of morphological preservation. The well-preserved tracks have tetradactyl digit impressions caused by both manus and pes, and are the type series of a new artiodactyl ichnotaxon, Fustinianapodus arriazui ichnogen. nov. and ichnosp. nov. The rest of the tracks, which are not as well preserved, are didactyl and were classified as undetermined artiodactyl tracks. According to their preservation, morphology, size, arrangement and orientation, we propose that this tracksite is the product of a social behaviour, particularly gregariousness, of a multi-age group of artiodactyls ~19 Ma ago. The morphologic and palaeoecologic data presented here suggest that the trackmakers were a group of anthracotheres with a livelihood similar to current hippos. They crossed, periodically, a fresh water palustrine area along some preferential pathways (trails).

Characterization of ferruginous cements related with weathering of slag in a temperate anthropogenic beachrock.

This work outlines a temperate latitude beachrock occurrence, which represents the legacy of heavy anthropogenic environmental disturbance. The units contain high amounts of slag and iron-rich wastes derived from metallurgical activities that attest the impact of the past industrial development on such coastal systems. The exposition of the anthropogenic wastes to weathering processes, such as the influence of marine aerosols and the chemical attack of acid gases like the SOx coming from the nearby urban-industrial atmosphere, gave rise to the formation of early diagenetic ferruginous cements. A new analytical methodology based on the combination of micro-Raman spectroscopy (MRS), Raman chemical imaging, SEM-EDS and the Structural and Chemical Analyzer (SCA, an emerging system that hyphenates micro-Raman and SEM-EDS), was applied for the first time to characterize the ferruginous cements. The MRS analyses revealed Fe2+/Fe3+ oxides and oxyhydroxides, CaCO3 polymorphs and less frequently silicates. The Fe mineral species detected were hydrated goethite, hematite, magnetite, magnesioferrite, lepidocrocite and goethite. Complementary Raman imaging, SEM-EDS and SCA analyses unraveled the preferential distribution of hydrated goethite. The identified iron mineral phases are weathering sub-products of hematite commonly derived from atmospheric/aqueous leaching processes triggered by the chemical attack of the acid gases. EDS showed the existence of other elements such as Si, Mg, Cl, Na, Al, K and sporadically S that indicated the importance of permeability, atmospheric deposition and the acid attack. Additionally, calcite and gypsum minerals also evidenced the action of meteoric waters, dry deposition processes or the attack of SOx acid gases. The presence of such compounds is modifying the cement stratigraphy and suggests that the dissolution of carbonates is currently taking place. Those facts influence the erosive susceptibility and the release of the anthropogenic materials trapped originally in the beachrocks, which could act as potential secondary sources of contaminants to the coastal environment.

Optimisation of focused ultrasound extraction (FUSE) and microwave-assisted extraction (MAE) of hydrocarbons in geological chert samples.

The analysis of hydrocarbons in chert rocks provides a worthwhile source of information regarding the geochemical features of a depositional setting. Since the typical analytical procedure requires long Soxhlet extractions and the use of large quantities of sample (30-50 g), in this work we have optimised the focused ultrasound extraction (FUSE) and the microwave-assisted extraction (MAE) to make available a less severe procedure. In both cases a full experimental design including solvent mixture composition (Dichloromethane/Hexane/Acetone) and process variables (sonication time and cycles, and extraction temperature and time) by means of D-optimal designs. In the extracted fractions hydrocarbons (C(16)-C(40)) were analysed by gas-chromatography-mass spectrometry. In the case of FUSE the process variables were the most sensitive variables and the optimum conditions were defined at 60:40 DCM/Hex mixture and a sonication time of 30 min and 9 cycles. In the case of MAE all the variables shown a significant effect on the extraction yield and the most adequate conditions (60:30:10 DCM/Hex/Ace mixture and an irradiation time of 15 min at 110 °C) were established from the analysis of the response surface. Both methods were systematically applied with different chert samples collected in Cucho (Trebiño County, Burgos, Spain) and we were able to assure quantitative extractions (>85%) in the first extraction. Additionally, from the distribution patterns of n-alkanes obtained in the different chert samples (nodular chert, laminar chert and massive-brechoid chert) collected in Cucho, we were able to distinguish different origins and diagenetic history.

Non-destructive spectrometry methods to study the distribution of archaeological and geological chert samples.

The study of lithic raw materials recovered from archaeological sites offers relevant data on source catchment areas. Additionally, it can provide first hand information on artefact displacement, interchange networks and it can reflect the way in which the artefacts were employed. In order to characterize geological and archaeological chert samples and with the aim of finding an analytical fingerprint infrared and Raman spectroscopies were used for molecular analysis and X-ray Fluorescence spectrometry for elemental analysis. In this work, different chert samples coming from several localities with geological and archaeological importance from the Basque Country have been collected and analysed. As a consequence, Raman spectroscopy allowed to distinguish between alpha-quartz and moganite in chert samples without organic matter and it is suggested that the ratio of those two components is related to the source of the chert. In addition, the impurities that appear in the samples (CaCO(3), iron oxides and organic matter) can open new features to distinguish the samples and in this way, it would be possible to discuss the use and transport of the lithic artifacts from the sources to the final settlements.