“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

Microtektites in the Alpine foreland: evidence of a Chiemgau impact relationship

In the Chiemgau meteorite crater strewn field (Ernstson et al. 2010, and references therein) impact glasses are found widespread in various formations, and tektite-like bodies of a dense black glass with vesicles have attracted considerable attention (Fig. 1).


Fig. 1.Dense black glass particles from the Chiemgau impact strewn field frequently exhibiting tektite-like shape and twisted form similar to irghizites from the Zhamanshin impact crater. – Click to enlarge!

Only recently, outside the crater strewn field in the foothills of the Alps at some 1500 m altitude a systematic search for impact fallout has revealed not only abundant tiny iron silicide particles (e.g., minerals xifengite and gupeiite) but also microtektites widely distributed in the soils (Fig. 2, 3).

A more detailed report can be read HERE.

Added link:  Abstract presented at the LPSC 45th Lunar and Planetary Science Conference 2014


Fig. 3. Microtektites from the soil in the foothills of the Alps near the Chiemgau impact crater strewn field. Optical microscope images, 100 µm scale bar in each case. – Click to enlarge!

Microtektites Alpine Foreland Chiemgau impact

Fig. 4. SEM micrographs of microtektite-like glass particles show
very strange surface features and bizarre forms exhibiting micrometer-sized glass filaments and twisted bodies. – Click to enlarge!

Azuara impact geology

Diamictic impact ejecta in a new outcrop near Aguilón

by Daniel Gorgas, Ferran Claudin & Kord Ernstson (October 2013)

Aguilón exposure Azuara impact structure

On the occasion of foundation work for a windmill near Aguilón (Fig. 1) one of the authors (D.G.) once again came across an exposure of highlighting impact geology (Figs. 2, 3) that practically is self-explaining. A big roundish block of (probably) Malmian oncolitic limestone (Fig. 4) is embedded in a diamictite and in the broadest sense is part of this polymictic diamictic deposit within the northern ring anticline of the Azuara impact structure. Since other formation possibilities fail to explain this extraordinary setting (a big landslide, e.g.,  can be excluded because of lacking relief) the deposit is clear evidence of impact ejecta excavated from the growing Azuara impact cavity. The roundness of this big “ball” can be explained by rotation and transport under high confining pressure exerted by the now embedding diamictic material.  Continue reading

76th Annual Meteoritical Society Meeting (2013), Edmonton, Canada

meteoritical society meeting 2013 edmonton

The following contributions to the MetSoc Meeting may be downloaded here:

Michael A. Rappenglück, Frank Bauer, Michael Hiltl, Andreas Neumair, Kord Ernstson:


Poster CAIs mini Click Poster CAIs

Abstract download

(download problems? Click here: Abstract CAIs)


Andreas Neumair, Kord Ernstson:


Poster distal ejecta png  Click Poster Distal Ejecta

Abstract download

(download problems? Click here: Abstract distal ejecta )


Kord Ernstson, Werner Müller, Andreas Neumair:

Poster Nalbach Chiemgau mini  Click Poster Nalbach Chiemgau

Abstract download

(download problems? Click here: Abstract Nalbach – Chiemgau)


Frank Bauer, Michael Hiltl, Michael A. Rappenglück, Andreas Neumair, Kord Ernstson:

Poster hapkeite mini  Click Poster Hapkeite

Abstract download 

(download problems? Click here: Abstract hapkeite)


The Weaubleau impact structure “round rocks” (“Missouri rock balls”, “Weaubleau eggs”): possible analogues in the Spanish Azuara/Rubielos de la Cérida impact structures.

by Kord Ernstson & Ferran Claudin (July 2013)
Abstract. – The “round rocks” of the Weaubleau-Osceola impact structure have phenomenological counterparts in the Spanish Azuara/Rubielos de la Cérida impact structures where they occur within voluminous heavily brecciated rock units. Related nodular bodies within large monomictic movement breccias are observed also in the Ries impact structure. A process similar to the formation of monomictic impact breccias with rounded clasts as part of a mortar texture is suggested. A relation to the Weaubleau-Osceola “round rocks” may exist but not necessarily.

1 Introduction

The Weaubleau (or now Weaubleau-Osceola) circular feature in southwestern Missouri is a 19 km-diameter impact structure that formed in the Mid-Carboniferous about 330 million years ago (Evans et al. 2003).

A peculiar feature clearly restricted to and common throughout the Weaubleau structure are the “round rocks” called also “Missouri rock balls” or “Weaubleau eggs” (Figs. 1, 2). Originally considered to be of glacial origin they are in general attributed now to the impact event. The idea of a formation as mega-accrecionary lapilli has been discarded and a diagenetic formation from blasted siltstone clasts intermixed in the fallback breccia and subsequent silification is mostly discussed. Nonetheless, the process of formation is still poorly understood. Here, we present evidence of roughly similar nodules occurring in the Spanish large Azuara and Rubielos de la Cérida impact structures where different from the Weaubleau “round rocks” they can be observed how they developed in situ.

Fig. 1. Weaubleau “round rock”. The typical and most common size runs from golf-balls to grapefruit. Photo: Harmil, WIKIMEDIA COMMONS.

Continue reading

Impact deposit at the Moneva reservoir, Azuara impact structure (Spain)

Impact deposit at the Moneva reservoir, Azuara impact structure (Spain)

by Ferran Claudin, Daniel Gorgas & Kord Ernstson (March 2013)

In 2012 in the course of a field trip around the Moneva reservoir (Fig. 1, 2) one of the authors, Daniel Gorgas from Azuara who already in the past had frequently contributed important geologic observations to the Azuara impact research, came across a geologic setting that appeared to drastically deviate from the “normal” deposits well known to him as the extended young Tertiary sediments within the Azuara structure. Following his report we began to study the geological maps of the area around the reservoir (Fig. 2, 3) and then to investigate the outcrops in more detail.

Google Earth Azuara impact structure

Fig. 1. Location map for the investigated outcrops at the Moneva reservoir within the Azuara impact structure (roughly outlined by a dashed circle).  Continue reading

Suspected Saarland impact and Chiemgau impact – do they form a pair?

Saarland impact and Chiemgau impact locations on the map of Germany

Chiemgau impact: is there a parallel with the Saarland region?

The earlier stated assumption that the Chiemgau impact may have a counterpart in the Saarland region


has been strengthened by new finds and new geologic and petrographic features. A respective update article may be clicked here:


Azuara impact structure: The Daroca thrust geologic enigma – solved? A Ries impact structure analog

by Ferran Claudin & Kord Ernstson (2012)


A nappe-like thrust of Cambrian over Tertiary, the Daroca thrust, in northeast Spain has puzzled geologists since longtime. Because of a lacking root zone and a lacking relief it didn’t match a reasonable geologic pattern. In the younger regional geologic literature the thrust is nevertheless incorporated in Alpine regional tectonics. An obviously first closer investigation of the involved Cambrian and Tertiary units, their facies and structural setting leads to a model that relates the Daroca thrust to the nearby roughly 40 km-diameter Azuara impact structure. The thrust is part of the excavation stage of impact cratering which may have affected both the Cambrian plate and the diamictic Tertiary below. The model is strongly substantiated by comparison with the Ries impact structure where similar thrusts and related features occur. The Daroca thrust is one more example reflecting the work of the regional geologists who pretend the giant Azuara impact event with the formation of the Azuara impact structure and the adjacent about 70 km Rubielos de la Cérida  elongated impact basin never happened. Hence, all their regional geologic models still developed which completely ignore the impact and its radical influence on the Tertiary regional geology are without any scientific relevance. 

1 Introduction

Daroca Province of Zaragoza Spain

Fig. 1. Daroca, Province of Zaragoza, Spain.

The very nice town of Daroca in the Spanish Province of Zaragoza (Fig. 1) hides a peculiar geologic scenario – an enigma for geologists from time out of mind. Being enthroned above the town the geologic stratigraphy shows with a very sharp cut Cambrian dolomite (Ribota dolomite) over Tertiary young sediments (Fig. 2). Older layers over younger ones are not uncommon in geology, and overthrust and thrust faulting are related processes. Continue reading

New images – Azuara impact structure: peculiar megabrecciation near Moyuela

dikes in megabreccia

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