Impact-induced surface hardening of polished quartzite cobbles, Triassic Buntsandstein conglomerates, Northern Spain

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).

shocked and polished quartzite cobbles from Molina de Aragón

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”

Conducting hypervelocity impact experiments

Experimental hypervelocity crater generation

making hypervelocity impact craters in the lab

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.

The Mesoarchaean Maniitsoq structure, West Greenland – a possible giant ancient impact structure

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.

YDB impact: a new chapter

… 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”