Reminder: “The convincing identification of terrestrial meteorite impact structures: What works, what doesn’t, and why”

“The convincing identification of terrestrial meteorite impact structures: What works, what doesn’t, and why”

by Kord Ernstson & Ferran Claudin (Dec. 2013)

Abstract. – We use and variegate the title of this article published in Earth-Science Reviews to show how science may (mal)function, how scientific results are manipulated, and how a few exposed impact researchers (the authors of the Earth-Science Reviews article included) are counteracting exactly the ideas presented in that article.

1 Introduction 

“The convincing identification of terrestrial meteorite impact structures: What works, what doesn’t, and why” is the title of a comprehensive and in principle not too bad article written by Bevan M. French and Christian Koeberl and published in Earth-Science Reviews (French & Koeberl 2010). We however would like to take up this title to once more point to the large Azuara and Rubielos de la Cérida impact structures in Spain and the related controversy shedding light on how science is manipulated, in this case with regard to some impact researchers from the so-called “impact community” (whatever that may be).

2 What doesn’t work

With a slight modification we begin with “what doesn’t work”. As for the identification of meteorite impact structures it obviously doesn’t work to publish clear and generally accepted impact shock features (like they are addressed in that article) to get an impact structure being established. This holds true for both the Azuara and Rubielos de la Cérida impact sites that are still opposed vehemently by a few leading impact researchers. Apart from the manifold geologic and geophysical evidence like ubiquitous monomictic and polymictic breccias, large systems of monomictic and polymictic breccia dikes, enormous and extended megabreccias, shatter cones, extended impact ejecta, gravity and geomagnetic anomalies, the unambiguously established shock metamorphism like shock melt, planar deformation features (PDFs) and diaplectic glass in various minerals appears not to convince (title!) Christian Koeberl, Falko Langenhorst, John Spray and others. Therefore, we once more present a collection of impact shock features from the Azuara and Rubielos de la Cérida impact structures in Spain that have all been published earlier in various journals:

Azuara impact structure: Planar deformation features (PDFs)

PDFs shock effect Azuara impact  PDFs shock Azuara impact SEMPDFs Azuara impact shock effectPDFs histogram shock Azuara Therriault analysis

Fig. 1 A-D: PDFs in quartz from the Azuara impact structure. A, B: in quartzite rocks from the impact ejecta deposit (Pelarda Fm.). C: from a polymictic strongly shocked breccia. D: Frequency diagram of Azuara PDFs based on data elaborated by Dr. A. Therriault. All figures have been published earlier.

An independent investigation of PDFs in samples from the Azuara impact structure (a polymictic dike breccia and Pelarda Fm. ejecta) was made at the Geological Survey of Canada by Dr. Ann Therriault (Therriault 2000). She analyzed the crystallographical orientation of PDFs in quartz (Fig. 1 D) and other parameters such as density, sharpness, spacing, and spreading over the grain (Fig. 1 C). And we cite from her report: Up to five sets of PDFs per grain were observed. The spacing is 1 µm or less, the PDF density high. Practically all sets are decorated. All shocked grains have reduced birefringence of 0.004 – 0.008.  Continue reading

“Impact Geology: The Basics” – new book

Bildschirmfoto 2017-09-12 um 10.53.25  Dr. Lynn B. Lundberg

“What is Impact Geology, and why should we study the subject? This volume is aimed at answering this question. Here Impact Geology is defined as the branch of geology that deals with the effects of impacts of smaller terrestrial bodies onto the surfaces of larger terrestrial objects such as planets, satellites, asteroids, comets, and other significant cold, solid bodies in our solar system…yes including Earth. The importance of this branch of geology cannot be overemphasized because impacts have played a major role in the formation of most geologic features on the surfaces of every terrestrial object in our solar system.”

So Lynn B. Lundberg begins the first chapter of his book IMPACT GEOLOGY: THE BASICS that was published in December 2016. This date reminds of the year 1989 when H.J. Melosh published his book “Impact Cratering – a Geologic Process”. This is nearly 30 years ago, and since then it has possibly become the most referred quotation in the impact research literature, although meteorite impacts, impact cratering and impact geology have remained a closed book to most geologists worldwide, unmissable until today.

Hence, we hope that this new book can establish itself as a worthy successor of the Melosh book and get widely disseminated. As an iBook it is available at the iBook store free of charge, and with the permission of the author you may download his book HERE as a pdf version.

Impact educational

Dear visitor of our website,

in the last years we have observed a permanently increasing number of page views, and statistics counted more than 9,000 (nine thousand) just for the last four weeks and solely for the English version. And statistics also said that a very high percentage of the views have accounted for the page on “Understanding the Impact Cratering Process: a Simple Approach“. This was the initial spark to introduce a new category “Impact educational” that may be clicked in the top menu from now on. Moreover, we got clear about the fact that many of our scientific contributions – to say it geologically – have sedimented and buried to deeper and deeper layers, and many an article may have become subject even to subduction and oblivion – despite all search engines. Hence, our new “Impact educational” category especially intends to excavate older impact literature of particular importance and interest, and specific subject areas earlier discussed on our homepage will step by step be brought into a new context also integrating new research aspects and publications. Make a test and read about meteorite impact spallation, including a chapter on dynamic spallation vs. tectonic stress – fractured pebbles as a stress indicator!