The investigation of the Azuara and Rubielos large impact structures now lasts about 30 years. Since the early eighties of the last century we have produced abundant and very exciting evidence for this unique geological scenario on the Iberian peninsula – despite much bitter opposition from various sides, persons and for various motives, which can be looked up elsewhere on this website. Much of our geological and petrographical material is being presented here in the web, but it is only part of an accumulation many times greater. Therefore we have decided to add little by little to the complex of the Azuara and Rubielos de la Cérida impact geology, and we don’t give up hope that a few more geologists become motivated to visit this extraordinary meteorite impact ensemble of some 120 km length.
We begin with an outcrop scenario easily accessible roadside at the village of Moyuela in the middle of the Azuara structure (Fig. 1) typically showing the enormous destruction the impact exerted on the well-bedded Jurassic limestones, which is inexplicable by normal Alpidic tectonics.
Continue reading “New images – Azuara impact structure: peculiar megabrecciation near Moyuela”
by Kord Ernstson & Ferran Claudin (2012)
Shocked quartzite cobbles making up widely spread Triassic Buntsandstein conglomerates in Northern Spain have been reported (Ernstson et al. 1999, 2001) to be related to the Mid-Tertiary large Azuara multiple impact event with the formation of the Azuara impact structure and the Rubielos de la Cérida elongated impact basin (Hradil et al. 2001, Ernstson et al. 2001, 2002, Schüssler et al. 2002, Claudin & Ernstson 2003, Ernstson et al. 2003). The quartzite cobbles (and boulders) are peculiarly and intensively pockmarked and cratered (Figs. 1, 2) and show in general a closely spaced subparallel fracturing (Fig. 3). The cobbles’ characteristics become especially evident when they are found scattered in the field as a result of the conglomerate weathering (Fig. 4).
Fig. 1. Typically pockmarked, cratered and polished (the large boulder) quartzite cobbles and boulders from the Triassic Buntsandstein conglomerates.
Continue reading “Impact-induced surface hardening of polished quartzite cobbles, Triassic Buntsandstein conglomerates, Northern Spain”
Experimental hypervelocity crater generation
“Understanding the Impact Cratering Process: a Simple Approach” – Now, we added a submenu to this item comprising records with a high-speed camera of a true hypervelocity impact in the laboratory and some explanations. A video that shows the formation of an impact crater can be downloaded THERE. Results of more experiments will be posted soon.
In the 1 July 2012 issue of the Earth and Planetary Science Letters journal an article has been published on a suspected 100 km sized impact structure that on verification would document the oldest cosmic collision on Earth so far known.
Adam A. Garde, Iain McDonald, Brendan Dyck, Nynke Keulen: Searching for giant, ancient impact structures on Earth: The Mesoarchaean Maniitsoq structure, West Greenland. – Earth Planet. Sci. Let., vol. 337-338, 197-210.
… or a “Requiem” for the rejection of the hypothesis?
YDB abbreviates Younger Dryas Boundary. The Younger Dryas stadial signifies a sharp onset of a period of cold climatic conditions in Earth’s history lasting roughly 1,000 years between about 11,000 and 10,000 B.C. at the end of the Pleistocene (the “Ice Age”) and the beginning Holocene.
The causes of this event are controversially disputed, and they are conventionally ascribed to perturbations of North Atlantic circulation. In 2007, a new hypothesis on a giant meteorite impact Continue reading “YDB impact: a new chapter”