Elmar Buchner | Universität Stuttgart (original) (raw)
Papers by Elmar Buchner
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Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2007
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2013
Kurzfassung: Europa bietet ein reiches Erbe an Impaktstrukturen von unterschiedlichster Größe, im... more Kurzfassung: Europa bietet ein reiches Erbe an Impaktstrukturen von unterschiedlichster Größe, im Bereich einiger Meter bis hin zu mehreren zehner Kilometern, und unterschiedlichsten geologischen Altern, vom Proterozoikum bis ins Quartär. Das Ries-Steinheim-Ereignis in Süddeutschland gilt als Paradebeispiel für einen Doppeleinschlag und hat zwei der weltweit am besten erhaltenen komplexen Impaktkrater hinterlassen. In dieser Zusammenschau werden die Impaktstrukturen in Deutschland, Frankreich, Osteuropa und den Baltischen Staaten, in Finnland, Schweden und Norwegen sowie Impaktauswurfmassen in Schottland und anderenorts kurz vorgestellt und neueste Ergebnisse in der europäischen Impaktkraterforschung präsentiert.
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2013
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2013
ABSTRACT The 3.8 km wide Steinheim Basin in SW Germany is a complex impact crater with central up... more ABSTRACT The 3.8 km wide Steinheim Basin in SW Germany is a complex impact crater with central uplift hosted by a sequence of Triassic to Jurassic sedimentary rocks. It exhibits a well-preserved crater morphology, intensely brecciated limestone blocks that form the crater rim as well as distinct shatter cones in limestones. In addition, an impact breccia mainly composed of Middle to Upper Jurassic limestones, marls, mudstones and sandstones is known from drilling into the impact crater. No impact melt lithologies, however, have so far been reported from the Steinheim Basin. In samples of the breccia that were taken from drill cores we discovered small silicate particles (up to millimetres in size) that contain Fe-Ni-Co sulphides , as well as target rock clasts (shocked and unshocked quartz, feldspar, limestone) and droplet-shaped particles of calcite. The particles exhibit distinct flow structures and relicts of schlieren and vesicles. From the geochemical composition and the textural properties, we interpret these particles as mixed silicate melt fragments widely recrystallised, altered and/or transformed into hydrous phyllosilicates. Furthermore, we detected schlieren of lechatelierite and recrystallised carbonate melt. On the basis of impactite nomenclature, the glass-bearing impact breccia in the Steinheim Basin can be denominated as “Steinheim Suevite”.
The so-called "Jebel Waqf as Suwwan" structure (Arabic for "Mountain of steeply inclined chert") ... more The so-called "Jebel Waqf as Suwwan" structure (Arabic for "Mountain of steeply inclined chert") located in the Hamada desert of Northeast Jordan, close to the Saudi Arabian border (centered at N 31˚03', E 36˚48'), has been recently reconsidered as the first complex impact structure in the Middle East . These inferences are based on its morphology showing a ∼5.5 km wide near-circular uplifted crater rim and a prominent central uplift, the occurrence of shatter cones as macroscopic shock evidence [2], and planar deformation features (PDFs) observed optically in quartz grains from the Cretaceous "Kurnub sandstone" [1] and shocked chert from the central uplift [3]. The eroded impact structure is emplaced in a nearly horizontal sequence of upper Cretaceous to Paleogene sandstones, limestones, marls, and cherts 4]. A Miocene-Pliocene impact age has been suggested .
Introduction: Construed as the result of a collapsing ejecta plume since 1977 [1], the formation ... more Introduction: Construed as the result of a collapsing ejecta plume since 1977 [1], the formation and emplacement of the Ries suevite was recently reinterpreted as a result of (a) ground-hugging impact melt flows [2], or (b) 'phreatomagmatic eruptions' that were caused by the interaction of surficial water with an impact melt pool [3,4]. Furthermore, [5] pointed out a striking similarity between structural features in suvites and ignimbrites (compare . Ignimbrites are deposits of pyroclastic density currents (pyroclastic flows), a hot suspension of particles and gas driven by the collaps of an eruptive column. The deposits are composed of a poorly-sorted mixture of volcanic ash and pumice, commonly with scattered lithic fragments; various stages of welding and reomorphic flow structures can be observed [6]. They usually exhibit a fine-grained, often nonerosive, basis (surge), followed by ash layers that contain inversely graded rock fragments. Bottom-up, ignimbrites are dominated by pumice-rich ash layers, overlain by very fine-grained fall-back ashes [7]; elutriation (degassing) pipes are frequently developed at the top.
Der miozäne Vulkanismus auf der Schwäbischen Alb mit seinen über 350 Eruptionszentren ist wenig b... more Der miozäne Vulkanismus auf der Schwäbischen Alb mit seinen über 350 Eruptionszentren ist wenig bekannt und förderte chemisch sehr homogene Schmelzen. Im vorliegenden Beitrag beschreiben wir das geologische Umfeld des Urach-Kirchheimer Vulkangebiets und eines der wenigen Sepiolithvorkommen in Deutschland aus Olivin-Melilithiten des Sternbergs.
![Research paper thumbnail of Comment on: “Direct evidence of ancient shock metamorphism at the site of the 1908 Tunguska event”, by P. Vannucchi et al. [Earth Planet. Sci. Lett. 409 (2015) 168–174]](https://attachments.academia-assets.com/48194320/thumbnails/1.jpg)
](Earth and Planetary Science Letters, 2015
ABSTRACT THE STEINHEIM BASIN IMPACT CRATER (GERMANY) – WHERE IS THE EJECTA BLANKET? E. Buchner1,2... more ABSTRACT THE STEINHEIM BASIN IMPACT CRATER (GERMANY) – WHERE IS THE EJECTA BLANKET? E. Buchner1,2 and M. Schmieder3. 1HNU - Neu-Ulm University, Germany.2Institut für Mineralogie, Universtität Stuttgart, Germa-ny. E-mail: elmar.buchner@hs-neu-ulm.de. 3School of Earth and Environment, University of Western Australia, Australia. Introduction: The ~24 km Nördlinger Ries and the ~3.8 km Steinheim Basin impact craters (e.g., [1]) are situated on the Upper Jurassic limestone plateau of the Swabian-Franconian Alb. Both impact craters are thought to have formed simultaneously in the Middle Miocene by the impact of a binary asteroid (e.g., [2]). The Nördlinger Ries crater is unique in terms of the state of preservation of the crater shape and its impact ejecta blanket. The Steinheim Basin today exhibits a distinct morphological depression that is filled by a lithic impact breccia preserved in its original thickness and position. Impact ejecta further outside the Steinheim crater have never been described in the literature. Description of the Problem: The transfer of up to 2 crater radii for a continuous ejecta blanket and of 2 to 3 crater diameters for distal ejecta (e.g., [3]) can be estimated for terrestrial impact structures. Proximal and medial Steinheim ejecta could be expected within a distance of up to 4 km, distal ejecta within a distance of up to 12 km from the crater rim, however, an intense search for proximal or distal Steinheim ejecta was not successful. The contradiction of a widely preserved ejecta blanket surrounding the Ries crater, the essentially identical sedimentary target setting and erosional history of the Ries and the Steinheim area, and the apparent lack of remnants of the Steinheim ejecta outside the crater have to be explained. Discussion and Results: Is the absence of Steinheim ejecta outside the crater a primary effect or the result of intense erosion? Paleogene (pre-Ries), Miocene (deposited chronologically close to the time of impact) and Miocene (post-impact) sediments occur in the surroundings of the Steinheim Basin within a distance of a few kilometers. These remains of sedimentary deposits suggest that Steinheim ejecta most probably would have survived if originally deposited in considerable amount. Target porosity has a significant influence on cratering efficiency as well as on the volume and distribution of excavated ballistic impact ejecta (e.g., [4]). The excavated volume of ejecta with high velocities drastically reduces with an increase in porosity. The (partial or total) suppression of ballistic ejecta outside the impact structure occurs when craters are formed mostly by compaction, which requires target porosities greater than about 30–40% [4]. The average porosity of the Steinheim target rocks range between a minimum of ~21% and a maximum of ~44 %. Due to the intensely karstified Upper Jurassic carbonate target rocks that represent the main portion of the Steinheim target rocks, the total target rock porosity probably tends towards the upper limit and is capable of reducing ballistic impact ejecta outside the impact structure drastically. As a result, we interpret the apparent absence of Steinheim ejecta presently observed in the surroundings of the crater as a likely primary effect of compression of the porous target rock and a concomitant significant reduction (suppression) of ballistically transported ejecta outside the crater. References: [1] Buchner, E. and Schmieder, M. 2010. Mete-oritics Planet. Sci. 45:1093-1107. [2] Stöffler, D. et al. 2002. Meteoritics Planet. Sci. 37:1893-1907. [3] Melosh, J. 1989. Im-pact Cratering: A Geologic Process. 245p. [4] Housen, K.R. and Holsapple, K.A. 2012. Icarus 219:297-306.
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2013
M. (2013): Das Ries-Steinheim-Ereignis -Impakt in eine miozäne Seen-und Sumpfl andschaft. [The Ri... more M. (2013): Das Ries-Steinheim-Ereignis -Impakt in eine miozäne Seen-und Sumpfl andschaft. [The Ries-Steinheim event -impact into a Miocene swampy lakescape.] -Z. Dt. Ges. Geowiss., 164: 459-470, Stuttgart.
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Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2007
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2013
Kurzfassung: Europa bietet ein reiches Erbe an Impaktstrukturen von unterschiedlichster Größe, im... more Kurzfassung: Europa bietet ein reiches Erbe an Impaktstrukturen von unterschiedlichster Größe, im Bereich einiger Meter bis hin zu mehreren zehner Kilometern, und unterschiedlichsten geologischen Altern, vom Proterozoikum bis ins Quartär. Das Ries-Steinheim-Ereignis in Süddeutschland gilt als Paradebeispiel für einen Doppeleinschlag und hat zwei der weltweit am besten erhaltenen komplexen Impaktkrater hinterlassen. In dieser Zusammenschau werden die Impaktstrukturen in Deutschland, Frankreich, Osteuropa und den Baltischen Staaten, in Finnland, Schweden und Norwegen sowie Impaktauswurfmassen in Schottland und anderenorts kurz vorgestellt und neueste Ergebnisse in der europäischen Impaktkraterforschung präsentiert.
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2013
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2013
ABSTRACT The 3.8 km wide Steinheim Basin in SW Germany is a complex impact crater with central up... more ABSTRACT The 3.8 km wide Steinheim Basin in SW Germany is a complex impact crater with central uplift hosted by a sequence of Triassic to Jurassic sedimentary rocks. It exhibits a well-preserved crater morphology, intensely brecciated limestone blocks that form the crater rim as well as distinct shatter cones in limestones. In addition, an impact breccia mainly composed of Middle to Upper Jurassic limestones, marls, mudstones and sandstones is known from drilling into the impact crater. No impact melt lithologies, however, have so far been reported from the Steinheim Basin. In samples of the breccia that were taken from drill cores we discovered small silicate particles (up to millimetres in size) that contain Fe-Ni-Co sulphides , as well as target rock clasts (shocked and unshocked quartz, feldspar, limestone) and droplet-shaped particles of calcite. The particles exhibit distinct flow structures and relicts of schlieren and vesicles. From the geochemical composition and the textural properties, we interpret these particles as mixed silicate melt fragments widely recrystallised, altered and/or transformed into hydrous phyllosilicates. Furthermore, we detected schlieren of lechatelierite and recrystallised carbonate melt. On the basis of impactite nomenclature, the glass-bearing impact breccia in the Steinheim Basin can be denominated as “Steinheim Suevite”.
The so-called "Jebel Waqf as Suwwan" structure (Arabic for "Mountain of steeply inclined chert") ... more The so-called "Jebel Waqf as Suwwan" structure (Arabic for "Mountain of steeply inclined chert") located in the Hamada desert of Northeast Jordan, close to the Saudi Arabian border (centered at N 31˚03', E 36˚48'), has been recently reconsidered as the first complex impact structure in the Middle East . These inferences are based on its morphology showing a ∼5.5 km wide near-circular uplifted crater rim and a prominent central uplift, the occurrence of shatter cones as macroscopic shock evidence [2], and planar deformation features (PDFs) observed optically in quartz grains from the Cretaceous "Kurnub sandstone" [1] and shocked chert from the central uplift [3]. The eroded impact structure is emplaced in a nearly horizontal sequence of upper Cretaceous to Paleogene sandstones, limestones, marls, and cherts 4]. A Miocene-Pliocene impact age has been suggested .
Introduction: Construed as the result of a collapsing ejecta plume since 1977 [1], the formation ... more Introduction: Construed as the result of a collapsing ejecta plume since 1977 [1], the formation and emplacement of the Ries suevite was recently reinterpreted as a result of (a) ground-hugging impact melt flows [2], or (b) 'phreatomagmatic eruptions' that were caused by the interaction of surficial water with an impact melt pool [3,4]. Furthermore, [5] pointed out a striking similarity between structural features in suvites and ignimbrites (compare . Ignimbrites are deposits of pyroclastic density currents (pyroclastic flows), a hot suspension of particles and gas driven by the collaps of an eruptive column. The deposits are composed of a poorly-sorted mixture of volcanic ash and pumice, commonly with scattered lithic fragments; various stages of welding and reomorphic flow structures can be observed [6]. They usually exhibit a fine-grained, often nonerosive, basis (surge), followed by ash layers that contain inversely graded rock fragments. Bottom-up, ignimbrites are dominated by pumice-rich ash layers, overlain by very fine-grained fall-back ashes [7]; elutriation (degassing) pipes are frequently developed at the top.
Der miozäne Vulkanismus auf der Schwäbischen Alb mit seinen über 350 Eruptionszentren ist wenig b... more Der miozäne Vulkanismus auf der Schwäbischen Alb mit seinen über 350 Eruptionszentren ist wenig bekannt und förderte chemisch sehr homogene Schmelzen. Im vorliegenden Beitrag beschreiben wir das geologische Umfeld des Urach-Kirchheimer Vulkangebiets und eines der wenigen Sepiolithvorkommen in Deutschland aus Olivin-Melilithiten des Sternbergs.
Earth and Planetary Science Letters, 2015
ABSTRACT THE STEINHEIM BASIN IMPACT CRATER (GERMANY) – WHERE IS THE EJECTA BLANKET? E. Buchner1,2... more ABSTRACT THE STEINHEIM BASIN IMPACT CRATER (GERMANY) – WHERE IS THE EJECTA BLANKET? E. Buchner1,2 and M. Schmieder3. 1HNU - Neu-Ulm University, Germany.2Institut für Mineralogie, Universtität Stuttgart, Germa-ny. E-mail: elmar.buchner@hs-neu-ulm.de. 3School of Earth and Environment, University of Western Australia, Australia. Introduction: The ~24 km Nördlinger Ries and the ~3.8 km Steinheim Basin impact craters (e.g., [1]) are situated on the Upper Jurassic limestone plateau of the Swabian-Franconian Alb. Both impact craters are thought to have formed simultaneously in the Middle Miocene by the impact of a binary asteroid (e.g., [2]). The Nördlinger Ries crater is unique in terms of the state of preservation of the crater shape and its impact ejecta blanket. The Steinheim Basin today exhibits a distinct morphological depression that is filled by a lithic impact breccia preserved in its original thickness and position. Impact ejecta further outside the Steinheim crater have never been described in the literature. Description of the Problem: The transfer of up to 2 crater radii for a continuous ejecta blanket and of 2 to 3 crater diameters for distal ejecta (e.g., [3]) can be estimated for terrestrial impact structures. Proximal and medial Steinheim ejecta could be expected within a distance of up to 4 km, distal ejecta within a distance of up to 12 km from the crater rim, however, an intense search for proximal or distal Steinheim ejecta was not successful. The contradiction of a widely preserved ejecta blanket surrounding the Ries crater, the essentially identical sedimentary target setting and erosional history of the Ries and the Steinheim area, and the apparent lack of remnants of the Steinheim ejecta outside the crater have to be explained. Discussion and Results: Is the absence of Steinheim ejecta outside the crater a primary effect or the result of intense erosion? Paleogene (pre-Ries), Miocene (deposited chronologically close to the time of impact) and Miocene (post-impact) sediments occur in the surroundings of the Steinheim Basin within a distance of a few kilometers. These remains of sedimentary deposits suggest that Steinheim ejecta most probably would have survived if originally deposited in considerable amount. Target porosity has a significant influence on cratering efficiency as well as on the volume and distribution of excavated ballistic impact ejecta (e.g., [4]). The excavated volume of ejecta with high velocities drastically reduces with an increase in porosity. The (partial or total) suppression of ballistic ejecta outside the impact structure occurs when craters are formed mostly by compaction, which requires target porosities greater than about 30–40% [4]. The average porosity of the Steinheim target rocks range between a minimum of ~21% and a maximum of ~44 %. Due to the intensely karstified Upper Jurassic carbonate target rocks that represent the main portion of the Steinheim target rocks, the total target rock porosity probably tends towards the upper limit and is capable of reducing ballistic impact ejecta outside the impact structure drastically. As a result, we interpret the apparent absence of Steinheim ejecta presently observed in the surroundings of the crater as a likely primary effect of compression of the porous target rock and a concomitant significant reduction (suppression) of ballistically transported ejecta outside the crater. References: [1] Buchner, E. and Schmieder, M. 2010. Mete-oritics Planet. Sci. 45:1093-1107. [2] Stöffler, D. et al. 2002. Meteoritics Planet. Sci. 37:1893-1907. [3] Melosh, J. 1989. Im-pact Cratering: A Geologic Process. 245p. [4] Housen, K.R. and Holsapple, K.A. 2012. Icarus 219:297-306.
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2013
M. (2013): Das Ries-Steinheim-Ereignis -Impakt in eine miozäne Seen-und Sumpfl andschaft. [The Ri... more M. (2013): Das Ries-Steinheim-Ereignis -Impakt in eine miozäne Seen-und Sumpfl andschaft. [The Ries-Steinheim event -impact into a Miocene swampy lakescape.] -Z. Dt. Ges. Geowiss., 164: 459-470, Stuttgart.