Dieter Stöffler

Museum für Naturkunde - Leibniz Institute for Research on Evolution and Biodiversity | MFN · Research Department

With this addendum we provide some correction and additional information regarding the above cited publication. It addresses the following two topics. (1) Clarification for a correct application of the criteria for certain shock stages of chondrites, in particular stage C‐S6. (2) Correction of a printing error in the table that contains the shock c...

Drill core petrography from the Rochechouart impact structure.

First results from the Rochechouart impact crater drilling campaign.

We analyzed the interaction of spherical, 6.36-mm-diameter, Cu-bearing aluminum projectiles with quartz sand targets in hypervelocity impact experiments performed at NASA Ames Vertical Gun Range. Impact velocities and inferred peak shock pressures varied between 5.9-6.5 km/s and ~41-48 GPa, respectively. Shocked particles ("impact melt particles")...

We reevaluate the systematics and geologic setting of terrestrial, lunar, Martian, and asteroidal “impactites” resulting from single or multiple impacts. For impactites derived from silicate rocks and sediments, we propose a unified and updated system of progressive shock metamorphism. “Shock-metamorphosed rocks” occur as lithic clasts or melt part...

The Tissint meteorite, a picritic shergottite, fell to Earth in Morocco on the 18th of July 2011, and is only the fifth Martian meteorite witnessed to fall. Hydrogen isotope ratios and water contents are variable within different minerals in Tissint. Ringwoodite and shock melt pockets contain elevated D/H ratios relative to terrestrial values (δD =...

Introduction: Hypervelocity impacts create high-pressure shock waves that lead to distinct shock-metamorphic effects in both projectile and target. Specifically, the point of impact is surrounded by hemispherical zones of decreasing shock pressure and, hence, by a continuum of decreasingly intense shock-metamorphic effects in the target material [1...

We investigated the ejection mechanics by a complementary approach of cratering experiments, including the microscopic analysis of material sampled from these experiments, and 2-D numerical modeling of vertical impacts. The study is based on cratering experiments in quartz sand targets performed at the NASA Ames Vertical Gun Range. In these experim...

We analyzed the interaction of spherical, 6.36-mm-diameter, Cu-bearing aluminum projectiles with quartz sand targets in hypervelocity impact experiments performed at NASA Ames Vertical Gun Range. Impact velocities and inferred peak shock pressures varied between 5.9 and 6.5 km/s and ∼41 and 48 GPa, respectively. Shocked particles (“impact melt part...

We present the results of numerical modeling of the formation of the Ries crater utilizing the two hydrocodes SOVA and iSALE. These standard models allow us to reproduce crater shape, size, and morphology, and composition and extension of the continuous ejecta blanket. Some of these results cannot, however, be readily reconciled with observations:...

We report results of an interdisciplinary project devoted to the 26 km-diameter Ries crater and to the genesis of suevite. Recent laboratory analyses of "crater suevite" occurring within the central crater basin and of "outer suevite" on top of the continuous ejecta blanket, as well as data accumulated during the past 50 years, are interpreted with...

We present the results of numerical modeling of the formation of the Ries crater utilizing the two hydrocodes SOVA and iSALE. These standard models allow us to reproduce crater shape, size, and morphology, and composition and extension of the continuous ejecta blanket. Some of these results cannot, however, be readily reconciled with observations:...

We present results of numerical modeling applied to various aspects of Ries crater formation and compare the results with observations. We also analyze existing analog models of suevite emplacement.

Why Study Impact Craters?" is the title of a fundamental contribution by one of the pioneers of impact crater research, Eugene M. Shoemaker, in a landmark book in this field: Impact and Explosion Cratering (Roddy et al. 1977). In his far-reaching vision, Shoemaker wrote: "I submit that impact of solid bodies is the most fundamental of all processes...

The transport mechanism of suevite particles during impact cratering is poorly understood and was studied at the 15 Ma Ries crater in southern Germany. Two emplacement modes of suevite deposits are generally discussed: (1) fallback of plume material into the crater and its periphery upon collapse of an ejecta plume; and (2) horizontal transport of...

Shock recovery experiments were performed with an explosive set-up in which three types of microorganisms embedded in various types of host rocks were exposed to strong shock waves with pressure pulse lengths of lower than 0.5 ls: spores of the bacterium Bacillus subtilis, Xanthoria elegans lichens, and cells of the cyanobacterium Chroococcidiopsis...

The transport mechanism of suevite particles during impact cratering is poorly understood and was studied at the 15 Ma Ries crater in southern Germany. Two emplace-ment modes of suevite deposits are generally discussed: (1) fallback of plume material into the crater and its periphery upon collapse of an ejecta plume; and (2) horizontal transport of...

Large-volume pseudotachylite bodies in impact structures are dike like and consist of angular and rounded wall-rock fragments enveloped by a microcrystalline and sporadically glassy matrix that crystallized from a melt. Knowledge of the formation of pseudotachylite bodies is important for understanding mechanics of complex crater formation. Most cu...

The transport mechanism of suevite particles during impact cratering is poorly understood and was studied at the 15 Ma Ries crater in southern Germany. Two emplace-ment modes of suevite deposits are generally discussed: (1) fallback of plume material into the crater and its periphery upon collapse of an ejecta plume; and (2) horizontal transport of...

Suevite and melt breccia compositions in the boreholes Enkingen and Polsingen are compared with compositions of suevites from other Ries boreholes and surface locations and discussed in terms of implications for impact breccia genesis. No significant differences in average chemical compositions for the various drill cores or surface samples are not...

Introduction: The ejecta blanket of the Chicxulub crater (Ø 180 km, 65 Ma) is one of the few examples for a well preserved ejecta blanket of large impact structures on Earth. It extends up to 5 crater radii from the center [1,2]. Due to this large runout it has been considered since its recognition as a primary example for comparative studies with...

Abstract— Imaging of asteroids Gaspra and Ida and laboratory studies of asteroidal meteorites show that impacts undoubtedly played an important role in the histories of asteroids and resulted in shock metamorphism and the formation of breccias and melt rocks. However, in recent years, impact has also been called upon by numerous authors as the heat...

Abstract— Using detailed geological, petrographic, geochemical, and geographical constraints we have performed numerical modeling studies that relate the Steinheim crater (apparent diameter Da = 3.8 km), the Ries crater (Da = 24 km) in southern Germany, and the moldavite (tektite) strewn field in Bohemia and Moravia (Czech Republic), Lusatia (East...

Presented numerical models cannot reproduce the previous hypotheses on suevite origin as plume-related non-ballistic ejecta. We suggest an alternative explanation.

A reevalution of the geologic setting and properties of suevite at the Ries Crater reveals a new hypothesis based on "phreato-magmatic"-like explosions of a clast-laden impact melt sheet induced by surficial water.

Abstract— Noble gas data from Martian meteorites have provided key constraints about their origin and evolution, and their parent body. These meteorites have witnessed varying shock metamorphic overprinting (at least 5 to 14 GPa for the nakhlites and up to 45–55 GPa (e.g., the lherzolitic shergottite Allan Hills [ALH] A77005), solar heating, cosmic...

Impact-induced ejections of rocks from planetary surfaces are frequent events in the early history of the terrestrial planets and have been considered as a possible first step in the potential interplanetary transfer of microorganisms. Spores of Bacillus subtilis were used as a model system to study the effects of a simulated impact-caused ejection...

The distribution of melt particles and basement clasts within the Chicxulub ejecta blanket suggests that vapor plume material overrun the ejecta curtain, was deposited first and subsequently eroded and incorporated by the secondary ejecta flow.

Roundness and sphericity of 1575 clasts from 14 localities of Chicxulub ejecta blanket were measured. Increasing particle abrasion with crater distance can be related to a viscous and erosive secondary flow with increasing strain localization.

The scenario of lithopanspermia describes the viable transport of microorganisms via meteorites. To test the first step of lithopanspermia, i.e., the impact ejection from a planet, systematic shock recovery experiments within a pressure range observed in martian meteorites (5-50 GPa) were performed with dry layers of microorganisms (spores of Bacil...

In this presented work we to revisited the suevite problem of the Ries cCater, Germany, in an interdisciplinary study by combining geological and petrograhic observations from Otting drill core with numerical models of crater and ejecta plume formation/deposition.

The Geopark Ries devoted to the Ries impact crater is currently under development. The Geopark covers an area of 1800 km2 comprising a total of 53 communities. The Ries has been certified as a national geopark in May 2006.

Formation conditions of suevite-like impactites from an ∼100 m thick drill core sequence through the Cretaceous-Tertiary Chicxulub crater were reconstructed from empirical data obtained by petrologic and image analytical methods. The temporal evolution of the cratering process from the initial stage of excavation to the collapse of the ejecta plume...

The large number of Martian meteorites with “young” crystallization ages (especially shergottites formed ∼ 170 Myr ago on Mars) represents a paradox, because it suggests that either the mean surface age of Mars is rather young or that specific source regions are preferentially amenable for impact sampling. We present a climate controlled scenario,...

Chemical analyses of soil samples performed at different landing sites on Mars suggest the presence of sulfate minerals. These minerals are also thought to be present in the globally mixed Martian bright soils covering large areas of the planet. However, remote soil spectra have so far provided only tentative identification of sulfates regarding mi...

Formation conditions of suevite-like impactites from a drill core in the Chicxulub crater were reconstructed by petrological and image analytical methods. This spans the temporal evolution of the cratering process from the initial stage of excavation to t

Petrographic and biological analysis of shock recovery experiments confirms the possible life transport due to an impact from Mars to Earth.

Bacterial spores (Bacillus subtilis), cyanobacteria (Chroococcidiopsis sp.), and lichen (Xanthoria elegans) embedded in martian analogue rock (gabbro) were exposed to shock pressures between 5 and 50 GPa which is the range of pressures observed in martian meteorites. The survival of Bacillus subtilis and Xanthoria elegans up to 45 GPa and of Chrooc...

In general terms, this interdisciplinary project represents an experimental contribution to the theory of “Lithopanspermia”. This theory has its roots in the work of Svante Arrhenius who formulated the theory of “Panspermia” in 1903 and postulated that microscopic forms of life, e.g. spores, can be dispersed in space by the radiation pressure from...

Bacterial spores (Bacillus subtilis), cyanobacteria (Chroococcidiopsis sp.), and lichen (Xanthoria elegans) embedded in martian analogue rock (gabbro) were exposed to shock pressures between 5 and 50 GPa which is the range of pressures observed in martian meteorites. The survival of Bacillus subtilis and Xanthoria elegans up to 45 GPa and of Chrooc...

Extract from introduction: The minerals of the Martian meteorites collected so far indicate an exposure to shock waves in the pressure range of 5 to 55 GPa [1]. As terrestrial rocks are frequently inhabited by microbial communities, rocks ejected from a planet by impact processes may carry with them endolithic microorganisms, if microbial life exis...

Ancient impact craters are commonly deeply eroded, metamorphosed and/or deformed by later tectonics. The identification of such impact structures using microstructural or mineralogical criteria are very difficult to apply under such conditions. It is proposed that fault patterns in the crater basement can be used diagnostically in eroded structures...

Abstract— To ascertain the progressive stages of shock metamorphism of zircon, samples from three well-studied impact craters were analyzed by optical microscopy, scanning electron microscopy (SEM), and Raman spectroscopy in thin section and grain separates. These samples are comprised of well-preserved, rapidly quenched impactites from the Ries cr...

Quantitative analyses of ejecta components at Chicxulub yield implications for oxidizing conditions in the ejecta plume and the depositional sequence of the continuous suevite-like deposits.

The suevites of the Chicxulub ejecta blanket from the UNAM 5 and 7 cores have been described in detail. The units defined do allow a correlation with impactites in the crater and help to reconstruct the emplacement of the ejecta plume material.

We investigate the likelihood of the theory of "Lithopanspermia", the hypothesis that viable microorganisms can be transported between terrestrial planets inside meteorites. On early Mars an evolution of life appears possible with respect to the geological and climatological development of the planet. Martian rocks can be impact ejected by moderate...

The Moon is exceptional and important because it is the only planetary body besides the Earth for which we have both a detailed stratigraphic history and datable rock samples that can be related to specific geomorphologic units (Fig. 5.1⇓). The Moon has preserved much of its magmatic and impact record of at least the last 4 billion years. While its...

Shock recovery experiments on a Martian analogue rock (gabbro) loaded with three types of microorganisms reveal that these organisms survive the impact and ejection phase on Mars at shock pressures up to about 50 GPa with exponentially decreasing survival rates.

The occurrence of diamonds in terrestrial impact craters and meteorites is related to dynamic shock loading during hypervelocity impacts. To understand the mechanism of impact diamond formation in natural rocks, shock-recovery experiments with graphite gneiss were carried out at shock pressures between 35 and 79 GPa. This is the first report on the...

In southern Quintana Roo (Mexico) the Chicxulub ejecta blanket is discontinuously filling a karstified pre-KT land surface. This suggests a completely new scenario for the geological evolution of the southern Yucatán Peninsula.

https://www.researchgate.net/publication/253794352_The_Steinheim_Impact_Crater_Germany_Modeling_of_a_Complex_Crater_with_Central_Uplift/file/72e7e520b7c5620e18.pdf

MERTIS is part of the payload of the Bepi-Colombo mission, focused on studying the surface of Mercury, identify rock-forming minerals and map the mineralogy globally with a resolution of 500m.

We present the first systematic Micro-Raman spectroscopic investigation of plagioclase of different degree of shock metamorphism in Martian meteorites. The equilibrium shock pressure of all plagioclase phases of seventeen unpaired Martian meteorites was determined by measuring the shock-induced reduction of the refractive index. Systematic variatio...

To constrain the formation conditions (P, T) and post-impact history of the suevite-like units (794-895 m) of Yax-1, a study of shock effects was undertaken in a previous stage of this project (e.g., 1, 2). The full range of progressive stages of shock metamorphism was found to occur in crystalline basement clasts of all suevitic units. However, al...