To play with Google Earth …

Taklamakan Desert (China): a mega-impact structure?

Kord Ernstson

University of Würzburg, 97074 Würzburg (Germany), kernstson@ernstson.de        

October 2020

Abstract.- A Google Earth-based morphological analysis of the Taklamakan Desert in the north of the Himalayas shows characteristics of a 1000 km mega-sized impact structure with an elliptical basin and a pronounced elliptical morphological rim. The elliptical structure may possibly have originated from the thrust of the Indian plate and the Himalayas. A gravity anomaly corresponds with the structure. More impact evidence is not known so far.

Key words: Taklamakan Desert, China, impact structure, gravity anomaly, Indian plate

A pdf full article may be downloaded here.

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Continue reading “To play with Google Earth …”

New article: Jiloca graben and Rubielos de la Cérida impact basin (NE Spain)

When modeling ignores observations: The Jiloca graben (NE Spain) and the Rubielos de la Cérida impact basin

by Kord Ernstson1 and Ferran Claudin2

June 2020

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Abstract. – The Iberian System in NE Spain is characterized by a distinctive graben/basin system (Calatayud, Jiloca, Alfambra/Teruel), among others, which has received much attention and discussion in earlier and very recent geological literature. A completely different approach to the formation of this graben/basin system is provided by the impact crater chain of the Rubielos de la Cérida impact basin as part of the important Middle Tertiary Azuara impact event, which has been published for about 20 years. Although the Rubielos de la Cérida impact basin is characterized by all the geological, mineralogical and petrographical impact findings recognized in international impact research, it has completely been hushed up in the Spanish geological literature to this day. The article presented here uses the example of the Jiloca graben to show the absolute incompatibility of the previous geological concepts with the impact structures that can be observed in the Jiloca graben without much effort. Digital terrain modeling and aerial photography together with structural and stratigraphic alien geology define a new lateral Singra-Jiloca complex impact structure with central uplift and an inner ring, which is positioned exactly in the middle of the Jiloca graben. Unusual topographic structures at the rim and in the area of the inner ring are interpreted as strike-slip transpression and transtension. Geological literature that still sticks to the old ideas and develops new models and concepts for the graben/basin structures, but ignores the huge meteorite impact and does not even enter into a discussion, must at best cause incomprehension.

Key words: Meteorite impact, Azuara impact event, Alfambra-Teruel graben, Calatayud basin, strike-slip transgression, transtension, Singra-Jiloca impact

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1 University of Würzburg, 97074 Würzburg (Germany), ernstson@ernstson.de                                                 

2 Associate Geological Museum Barcelona (Spain); fclaudin@xtec.cat

The full article can be clicked HERE.

An article pdf for download can be clicked HERE.

 

Daroca thrust (Iberian Chain, Spain) and the Azuara impact structure – the controversy continues

Comment on

Sanchez, M.A. ; Gil, A. y Simón, J.L. (2017): Las rocas de falla del cabalgamiento de Daroca (sector central de la Cordillera Ibérica): Interpretación reológica y cinemática. Geogaceta, 61: 75-78. (http://www.sociedadgeologica.es/archivos/geogacetas/geo61/geo61_19p75_78.pdf)

Casas-Sainz, A.M., Gil-Imaz, A., Simón, J.L., Izquierdo Llavall, Aldega, E.L., Román-Berdiel, T., Osácar, M.C., Pueyo-Anchuela, O., Ansón, M., García-Lasanta, C., Corrado, S., Invernizzi, C., Caricchi, C. (2018): Strain indicators and magnetic fabric in intraplate fault zones: Case study of Daroca thrust, Iberian Chain, Spain. Tectonophysics, 730: 29-47 (10.1016/j.tecto.2018.02.013) (https://zaguan.unizar.es/record/78325/files/texto_completo.pdf

Gutierrez, F, Carbonela, D., Sevil, J., Moreno, D., Linares, R, Comas, X., Zarroca, M., Roqué,C., McCalpin, J.P. (2020): Neotectonics and late Holocene paleoseismic evidence in the Plio-Quaternary Daroca Half-graben, Iberian Chain, NE Spain. Implications for fault sorce characterization. Journal of Structural Geology, 131: 1-17 (https://doi.org/10.1016/j.jsg.2019.103933)

by Ferran Claudin & Kord Ernstson (March 2020)

The town of Daroca in the Spanish Province of Zaragoza 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. A). Older layers over younger ones are not uncommon in geology, and overthrust and thrust faulting are related processes. But Daroca is different. The Cambrian plate is kilometer-sized and fragmented into larger blocks, and a Tertiary 180° overtrust can reasonably be excluded. Early geologists confronted with the situation in sheer desperation thought of a preexisting Cambrian autochthonous plate and a vast undercutting by the Tertiary. Today this explanation is left out of consideration and simple thrust faulting is being favored. But the case is all but simple. There is no root zone and not any relief from where the giant plate could have started to override the Tertiary around Daroca. Nevertheless, the thrust kinematics are developed further by geologists (e.g., Capote et al. 2002), and tens of kilometers long faults are drawn within models of syn-tectonic sedimentation (Casas et al. 2000; Fig. 3).

The Daroca (Spain) thrust and the Azuara impact structure

Fig. A. The prominent Daroca exposure.

In 2012 we published an extended article (Claudin and Ernstson 2012) under the title “Azuara impact structure: The Daroca thrust geologic enigma – solved? A Ries impact structure analog“.. which proposes a new and in our opinion reasonable model of formation and a physically plausible solution of the enigma. To cut the story short, the Daroca thrust originated in the meanwhile generally established Azuara impact event, when according to the spall plate model of Melosh (1989) the Daroca Ribota dolomite plate started from the developing excavation crater and the near-surface interference zone with extreme velocity (Fig. B), supported by enormous volumes of rock melt, water and gases (water vapor and carbon dioxide from the shocked target) as a kind of hovercraft. This is no speculation but has much earlier been discussed for the so-called role-and-glide mode in the excavation process of the Ries impact crater (Germany). In our paper on the Daroca thrust we write about the affinity of both events and point to Ries giant megablocks having been excavated and transported over enormous distances.

In the case of the Daroca thrust this impressive way of transport can so nicely and conclusively be observed on the geological general map 1 : 200 000, sheet Daroca, which we show in simplified manner below (Fig. B) and in a copy of the geological map in Fig. 11 of the Spanish complete version).

simplified geological map for the Daroca thrust origin The spall plate model of impact excavation

Fig. B. The impact cratering model for the Daroca thrust – no intraplate fault zone (see text).

We do not know with certainty whether the authors of the three papers have read our paper and whether they have understood the herein presented simple explanation, but strangely enough since the publication of our paper on the Daroca thrust with the close relation to the Azuara impact structure, practically “overnight” a series of publications has appeared to demonstrate that the Daroca thrust has a normal tectonic fault origin, after not any geologist from Spain or elsewhere had paid attention to the enigma for decades (apart from the Casas et al. (2000) and Capote et al. (2002) papers, only seeing a tectonic fault despite all non-tectonic field evidence).

Of course, science thrives on controversy on certain topics and especially on new discoveries and models, but one principle is that the different views should be on a scientific level and that both views should be carefully discussed and balanced.

In all three papers we miss the observance of this basic scientific constitution. Not a single word is used to mention the Daroca article and the Azuara impact structure in general, and not a single one of the abundant publications on one of the most spectacular geological scenarios in Spain is found in their works. Today the Internet is a common medium and broadly used to get information about serious scientific publications (ResearchGate e.g.), and on preparing their papers a few clicks by the authors of the three papers had of course opened a host of literature about the Azuara impact event and the Daroca thrust.

In principle our Comment article could therefore end here. But we do not want to make the same omission ignoring the papers under discussion here. In the main part of our Comment paper following below, F. Claudin has compiled an exhaustive analysis of the three Daroca “tectonic” papers confronting their in many respects rather questionable claims with standard geologic literature and with the impressive meteorite impact-related features, once more described here point by point with a host of figures that do not exist for the authors.

Exemplarily, one point of importance is addressed already here, the Casas-Sainz et. al. paper about magnetic fabric from AMS (anisotropy of magnetic susceptibility) and strain indicators. From the text we learn that magnetic AMS analyses were performed at 6 sites, but only a single one (no.16) is located in Daroca at the thrust exposure (their Fig. 2A). Since the site is navigated at fractures of a second, we have to proceed from a spot analysis (their Table. 1), and the rock for 12 specimen measurements is described as a fault microbreccia (their Table 3). The rest of the 5 AMS sites is located roughly 1 km southeast of Daroca (their Fig. 2A).

We imagine: For the Daroca thrust as described in very detail in our paper (Claudin & Ernstson 2012), a spot few meters sized at best served for an AMS analysis of a microbreccia (we assume of Ribota dolomite) for which it is obviously not known when it acquired the brecciation and a resulting AMS texture.

Considering now the Daroca thrust impact model of an enormously dislocated spall plate, which Casas-Sainz et al. completely ignore, what will a point AMS tell us about old in situ tectonics and intraplate fault zones? Nothing. The Daroca plate may have transported magnetic textures from its original place more than 10 km to the east, intense brecciation and other deformation (which can be seen in Daroca outcrops) in the excavation, ejection, transport and emplacement processes should have produced a completely new texture, not to forget possible strong temperature overprint in the impact cratering process.

The same holds true for the five other sites of AMS analyses. Since the aim and outcome of the paper is basically the AMS of the thrust zone, more than a little methodological insight into the authors’ working cannot be recognized. The paper of Gutierrez et al. (2020) does not differ in any way in this respect. Their ground penetrating radar (GPR) and resistivity measurements at Daroca are good to look at, but for the topic under discussion they are absolutely meaningless. The idea arises that the visual impression of scientific evidence for the so-called Daroca Half-graben is to be created by the pure application of a few geophysical measurements on a very small area.

The complete article (in Spanish) may be clicked here.

Chiemite: addition to the article below

Chiemite and Muschelkalk, sandstone facies, breccia-like interleaved - Saarland impact, cut face

Chiemite and Muschelkalk cobble are breccia-like interleaved. Saarland impact, cut face, centimeter scale.

The most recent find of chiemite in the Saarland impact region (Nalbach, Saarlouis craters) concerns a cobble in which a larger piece of chiemite is breccia-like interleaved with a cobble (probably Muschelkalk in predominantly sandy facies) (photos). This supports the idea that during the impact the chiemite was mainly formed from a carbon melt (vaporized and condensed carbon from the heavily shocked vegetation) and that when it hit the rock it created a vesicular texture in it (partially carbonate melt, decarbonization).

This find should at least make the self-appointed great impact experts on the Internet think about how the Muschelkalk limestone got into the coal cellar and intimately aggregated with the coke.

chiemite on Muschelkalk cobble, Saarland meteorite impact siteFrom the Saarland impact region: chiemite interleaved with Muschelkalk limestone/Muschelkalk sandstone (cut face in the entrance photo). Picture width 10 cm.

chiemite on vesicular Muschelkalk cobble, Saarland meteorite impact site

Chiemite remains on the blistered cobble surface.

Wikipedia: Chiemite impactite and the EGU poster deception with the Wikipedia name

SEM images chiemite and chiemite pseudomorphic after woodChiemite, which is described in international, renowned peer-reviewed publication organs as high pressure/high temperature impactite with the contents of diamond and carbines (T = 2500 – 4000 K, P = several GPa), is of terrestrial origin and has originated from a spontaneous shock coalification/carbonization of the vegetation (wood, peat) of the Chiemgau impact area. The published methods of the chiemite investigation were: optical and atomic force microscopy, X‐ray fluorescence spectroscopy, scanning and transmission electron microscopy, high‐resolution Raman spectroscopy, X‐ray diffraction and differential thermal analysis, as well as by δ13C and 14C radiocarbon isotopic data analysis.

The most comprehensive article on the chiemite impactite so far is published here:

Enigmatic Glass-like Carbon from the Alpine Foreland, Southeast Germany: A Natural Carbonization Process. – Acta Geologica Sinica (English Edition), 92, 2179-2200, 2018.

Tatyana G. SHUMILOVA, Sergey I. ISAENKO, Vasily V. ULYASHEV, Boris A. MAKEEV, Michael A. RAPPENGLÜCK, Aleksey A. VELIGZHANIN, Kord ERNSTSON

About the first author (from the Journal Editor). – Tatyana Shumilova, born in Vorkuta, Russian Federation, in December 1967. She received her PhD at the Institute of Geology UB Komi SC UB RAS in 1995. She was habilitated at the Saint-Petersburg Mining University (Leningrad Mining Institute) in 2003. At present she is a head of the Laboratory of Diamond Mineralogy and main scientist at the Institute of Geology UB Komi SC UB RAS and Affiliated Researcher at the University of Hawaii. She published over 50 papers in peer-reviewed journals such as Scientific Reports, Carbon, European Journal of Mineralogy, Mineralogy and Petrology, Doklady Earth Sciences, and others.

The background for these additions to the article is the following contrast:

At the this year’s (2019) meeting of the European Geosciences Union (EGU) in Vienna in April, Dr. Robert Huber (marine geologist at Marum, Center for Marine Environmental Sciences, University of Bremen) and Dr. Robert Darga (ice age geologist, director of the Mammut Museum in Siegsdorf, Chiemgau, Oberbayern) obviously succeeded in persuading some other scientists to present a joint poster, on which their crude ideas were presented: “If You Wish Upon A Star. Chiemite: An Anthropocene Pseudo-Impactite. “

Placing the poster in Wikipedia and Wikimedia Commons does not enhance the value of this poor attempt.

The three coauthors of the poster are from Australia – Mineral Resources, CSIRO, Federal Agency for the improvement of the economic and social performance of industry -, shedding some light on their relevant scientific competence. Scientifically the poster presentation of these impact critics, in which not a single reference is brought to the Chiemgau impact and not a single reference to the chiemite is absolutely worthless, far from any scientific seriousness, and should cause mockery at most in a respectable science scene. One wonders why the poster could be shown at all on the Vienna conference.

In the meantime, the chiemite impactite has been found widely in the Saarland impact region as well as in numerous specimens in the impact area of the Czech Republic Abstract Poster. In both cases the chiemites show identical formation and occur in both areas together with strongly shocked impact rocks.

chiemite impactite from the Saarland and Czech Republic impacts

Chiemite from the Saarland impact ………………………..and the Czech impact

Pelarda Fm. Impact Ejecta – Azuara Impact Structure (Spain)

Pelarda Fm. – Azuara Impact Structure (Spain) – comprehensive article on one of the biggest, most attractive and scientifically most instructive impact ejecta deposits worldwide

 

PDF article, 81 p., 92 Figs. – The full article can be clicked HERE.

Abstract. – The Pelarda Formation (Fm.), located in the Iberian System in northeast Spain, is a sedimentary deposit with an extension of roughly 12 km x 2.5 km and an estimated thickness of no more than 400 m. The formation was first recognized as a peculiar unit in the early seventies and underwent interpretations like a fluvial or an alluvial fan deposit having a postulated age between Paleogene and Quaternary. Since the early nineties the Pelarda Formation has been considered an impact ejecta deposit originating from the large ca. 40 km-diameter Azuara impact structure and meanwhile being among the largest and most prominent terrestrial impact ejecta occurrences, which however is questioned by regional geologists still defending the fluvial and alluvial fan models. Roughly speaking, the Pelarda Fm. is a grossly unsorted, matrix-supported diamictite with grain sizes between silt fraction and meter-sized clasts and a big intercalated megablock. Strong clast deformations and abundant shock metamorphic effects like planar deformation features (PDF) are observed throughout the Pelarda F. deposit compatible with its impact ejecta origin. Aligned bigger clasts and smaller intercalated bands of sandstones, siltstones and clayey material indicate some local stratification obviously adjusted to flow processes within the impact ejecta curtain. This suggests that gravitational flows predominated in a transport by water in both liquid and gas states. Transport and deposition as a kind of pyroclastic surge are discussed. A sketch sequence describes the emplacement process of the Pelarda Fm. as part of the Azuara crater formation and the integration in the general frame of pre-impact geology and some post-impact layering.

Key words: Pelarda Formation, Iberian System, Upper Eocene/Oligocene, Azuara impact structure, proximal impact ejecta, pyroclastic flow

Lairg (Northern Scotland): evidence of Europe’s largest impact structure

New article: Michael J. Simms and Kord Ernstson (2019): A reassessment of the proposed ‘Lairg Impact Structure’ and its potential implications for the deep structure of northern Scotland. – 

Bouguer gravity residual anomaly of the Lairg proposed impact structure. A buried complex structure with an inner peak ring of 50 km diameter und derived 100 km full diameter.
Probably the source for the Stac Fada Precambrian impact ejecta deposit.

Gravity residual profiles across the Lairg impact structure revealing an inner peak ring and peripheral depressions.

 

State of research on the Chiemgau Impact 2017 – English translation of the full article

MICHAEL RAPPENGLÜCK, BARBARA RAPPENGLÜCK, KORD ERNSTSON (2017):

Collision in prehistory. – The Chiemgau Impact: research in a Bavarian meteorite crater strewn field. – Zeitschrift für Anomalistik, vol. 17 (2017), p. 235-260. 

State of research on the Chiemgau Impact 2017 – English translation of the full article – click here.