A new fossil resin with biological inclusions in Lower Cretaceous deposits from Álava (northern Spain, Basque-Cantabrian Basin)

Abstract

The occurrence of amber in Sierra de Cantabria (álava, Basque Country) has been known for more than two decades but biological inclusions have only recently been found. The existence of crustaceans (amphipods and isopods), chelicerates (acari and arachnids), 12 orders of insects, and several bird feathers are reported in this preliminary study. In addition, there are leaf remains, molluscs, and a fair number of inorganic inclusions.Pollen analysis of the clastic series indicates an age between upper Aptian—middle Albian, which allows an assignment of this stratigraphic unit to the Nograro Formation. Chemical analysis indicates that the amber has high maturity, which reflects its Cretaceous age. Chemical composition analysis also indicates an araucariacean origin, which is corroborated by pollen found within the amber deposit.This new fossil site provides information for the reconstruction of paleocommunities of arthropods and sedimentary environments in the extreme south of the Basque-Cantabrian Basin during the Lower Cretaceous, characterized by coniferous forests with an understory of vascular cryptograms. Some of the identified arthropods add to the fossil record for various groups that are poorly known or unknown for this time period. This Lagerstätte constitutes one of the most important deposits of Mesozoic amber in the world.

Leonardo García Sanjuán, Chris Scarre and David W. Wheatley, eds. Exploring Time and Matter in Prehistoric Monuments: Absolute Chronology and Rare Rocks in European Megaliths (Proceedings of the 2nd European Megalithic Studies Group Meeting, Seville, Spain, November 2008, Menga: Journal of Andalusian Prehistory Monograph No. 1, Seville: Andalusian Government, 2011, 387pp., many illustrations including colour plates, hbk and CD, ISBN 978-9959-083-7)

“…En la Península Ibérica hay localizados varios yacimientos geológicos de ámbar, la mayoría datados en el Cretácico, que pudieron ser explotados desde el Paleolítico. Entre los más importantes destacan los de Peñacerrada (País Vasco y Burgos), San Just (Teruel) y El Soplao (Cantabria) (Alonso et al, 2000; …”

“…There are several geological deposits of amber located in the Iberian Peninsula, the majority dating from the Cretaceous, which could have been mined since the Palaeolithic. Among the most important, those at Peñacerrada (the Basque Country and Burgos), San Just (Teruel) and El Soplao (Cantabria) (Alonso et al, 2000; stand out. To date, no deposits of amber have been documented in the south of Spain, although there is one reference to the existence of geological amber deposits in the region of Grazalema (Cádiz) (Domínguez-Bella et al, 2001).…”

Fingerprinting of Cretaceous higher plant resins by infrared spectroscopy and gas chromatography coupled to mass spectrometry

“…Other common bands present constituted an unresolved group near 2930 cm −1 (C-H st), a band group that was the most intense in all spectra. The smooth profile of the bands between 1250 and 625 cm −1 (fingerprinting region) is characteristic of ancient samples (Grimalt et al, 1988;Alonso et al, 2000;Otto et al, 2002).…”

“…Fossil tree resins, commonly called ambers, are widespread and abundant in the geosphere, constituting a valuable source of paleobotanical and geochemical information (Grimalt et al, 1988;Anderson and Winans, 1991;Anderson et al, 1992;Wilson et al, 1992;Anderson and Botto, 1993;Anderson, 1994;Anderson and Crelling, 1995;Clifford et al, 1997;Alonso et al, 2000;Otto et al, 2002). Thus, their chemical composition provides evidence of their higher plant precursors and the diagenetic transformations that have occurred after deposition.…”

“…As examples, three fossil resins from Peñacerrada (Alava, Basque Country, North Spain) and Santander (located west of Peñacerrada, Cantabria, Spain) have been analysed by IR and GC-MS. The Peñacerrada deposit comprises 100 km 2 on the North Slope of the Cantabrian Sierra (Alonso et al, 2000). It is one of only four world sites aged older than 95 million years, the limit between the Upper Cretaceous and the Lower Cretaceous, and it is the only one known of Upper Aptian.…”