Geochemical studies of the <scp>SUBO</scp> 18 (Enkingen) drill core and other impact breccias from the Ries crater, Germany

Reimold, W. U.; McDonald, Iain; Schmitt, Rüdiger; Hansen, B. K.; Jacob, Juliane; Koeberl, Christian

doi:10.1111/maps.12175

Cited by 10 publications

(15 citation statements)

References 61 publications

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“…; Reimold et al. ; Schmitt et al. ) was divided into five groups: According to their chemistry, basic and ultrabasic rocks form the group of (1) mafic rocks, and rocks with high Ca content are called (2) Ca‐enriched rocks.…”

Section: Discussionmentioning

confidence: 99%

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Heterogeneity of melts in impact deposits and implications for their origin (Ries suevite, Germany)

Siegert

Hecht

2018

Meteorit & Planetary Scien

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Impact melt‐bearing clastic deposits (suevites) are one of the most important records of the impact cratering process. A deeper understanding of their composition and formation is therefore essential. This study focuses on impact melt particles in suevite at Ries, Germany. Textures and chemical evidence indicate that the suevite contains three melt types that originate from different shock levels in the target. The most abundant melt type (“melt type 1”) represents well‐mixed whole‐rock melting of crystalline basement and includes incompletely mixed mafic melt schlieren (“melt type 1 mafic”). Polymineralic melt type 2 comprises mixes between monomineralic melt types 3 and melt type 1. Melt types 2 and 3 are located within melt type 1 as small patches or schlieren but also isolated within the suevite matrix. The main melt type 1 is heterogeneous with respect to trace elements, varying geographically around the crater: in the western sector, it has lower values in trace elements, e.g., Ba, Zr, Th, and Ce, than in the eastern sector. The west–east zoning likely reflects the heterogeneous nature of crystalline basement target rocks with lower trace element contents, e.g., Ba, Zr, Th, and Ce, in the west compared to the east. The chemical zoning pattern of suevite melt type 1 indicates that mixing during ejection and emplacement occurred only on a local (hundreds of meters) scale. The incomplete larger scale mixing indicated by the preservation of these local chemical signatures, and schlieren corroborate the assumption that mixing, ejection, and quenching were very rapid, short‐lived processes.

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Section: Discussionmentioning

confidence: 99%

“…, Enkingen SUBO 18 drill core) resembles the outer suevite in texture, clast size, and shape (Reimold et al. , ; Stöffler et al. ).…”

Section: The Ries Suevitementioning

confidence: 99%

Heterogeneity of melts in impact deposits and implications for their origin (Ries suevite, Germany)

Siegert

Hecht

2018

Meteorit & Planetary Scien

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“…Notwithstanding decades of intense research, a number of open questions has remained, such as the composition of the impactor (Schmidt and Pernicka ; Reimold et al. ; Stöffler et al. ; Ackerman et al.…”

Section: Geographic and Geological Overviewmentioning

confidence: 99%

“…; Reimold et al. ; Stöffler et al. ), and the hypothetical effect of groundwater–melt interaction in the genesis of the suevite (Artemieva et al.…”

Section: Geographic and Geological Overviewmentioning

confidence: 99%

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The Erbisberg drilling 2011: Implications for the structure and postimpact evolution of the inner ring of the Ries impact crater

Arp

Reimer

Simon

et al. 2019

Meteorit & Planetary Scien

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The 26 km diameter Nördlinger Ries is a complex impact structure with a ring structure that resembles a peak ring. A first research drilling through this “inner crystalline ring” of the Ries was performed at the Erbisberg hill (SW Ries) to better understand the internal structure and lithology of this feature, and possibly reveal impact‐induced hydrothermal alteration. The drill core intersected the slope of a 22 m thick postimpact travertine mound, before entering 42 m of blocks and breccias of crystalline rocks excavated from the Variscan basement at >500 m depth. Weakly shocked gneiss blocks that show that shock pressure did not exceed 5 GPa occur above polymict lithic breccias of shock stage Ia (10–20 GPa), with planar fractures and planar deformation features (PDFs) in quartz. Only a narrow zone at 49.20–50.00 m core depth exhibits strong mosaicism in feldspar and {10true1false¯2} PDFs in quartz, which are indicative of shock stage Ib (20–35 GPa). Finally, 2 m of brecciated Keuper sediments at the base of the section point to an inverse layering of strata. While reverse grading of clast sizes in lithic breccias and gneiss blocks is consistent with lateral transport, the absence of diaplectic glass and melt products argues against dynamic overthrusting of material from a collapsing central peak, as seen in the much larger Chicxulub structure. Indeed, weakly shocked gneiss blocks are rather of local provenance (i.e., the transient crater wall), whereas moderately shocked polymict lithic breccias with geochemical composition and 87Sr/86Sr signature similar to Ries suevite were derived from a position closer to the impact center. Thus, the inner ring of the Ries is formed by moderately shocked polymict lithic breccias likely injected into the transient crater wall during the excavation stage and weakly shocked gneiss blocks of the collapsing transient crater wall that were emplaced during the modification stage. While the presence of an overturned flap is not evident from the Erbisberg drilling, a survey of all drillings at or near the inner ring point to inverted strata throughout its outer limb. Whether the central ring of the Ries represents remains of a collapsed central peak remains to be shown. Postimpact hydrothermal alteration along the Erbisberg section comprises chloritization, sulfide veinlets, and strong carbonatization. In addition, a narrow zone in the lower parts of the polymict lithic breccia sequence shows a positive Eu anomaly in its carbonate phase. The surface expression of this hydrothermal activity, i.e., the travertine mound, comprises subaerial as well as subaquatic growth phases. Intercalated lake sediments equivalent to the early parts of the evolution of the central crater basin succession confirm a persistent impact‐generated hydrothermal activity, although for less time than previously suggested.

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Emplacement of shocked basement clasts during crater excavation in the Ries impact structure

Dellefant,

Seybold,

Trepmann

et al. 2024

Int J Earth Sci (Geol Rundsch)

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In the Aumühle quarry of the Ries impact structure, moderately shocked clasts from the Variscan basement occur sandwiched between overlying suevite and components derived from the Mesozoic sedimentary cover of the underlying Bunte Breccia without distinct shock effects. We analyzed the clasts by optical microscopy, scanning electron microscopy (SEM/EDS/EBSD), and Raman spectroscopy to unravel their emplacement relation to the overlying suevite and the sediment-rock clasts of the Bunte Breccia. Clasts sizes range up to few decimeters and are embedded in a fine-grained lithic matrix; no impact-melt fragments are observed. Amphibolite clasts contain maskelynite with few lamellar remnants of feldspar, indicating shock pressures of 28–34 GPa. Amphiboles have cleavage fractures and ($$\overline{1}$$ 1 ¯ 01) mechanical twins suggesting differential stresses > 400 MPa. Felsic gneiss components have optically isotropic SiO2 indicative of shock pressures ≈35 GPa. Metagranite cataclasite clasts contain shocked calcite aggregates and quartz with a high density of fine rhombohedral planar deformation features indicating shock pressures ≈20 GPa. The moderately shocked basement clasts originate from deeper levels of the transient cavity and lower radial distance to the center of the structure compared to the sediment-rock clasts. Both were ballistically ejected during crater excavation. In accordance with palaeo- and rock magnetic data, they were mixed during turbulent deposition at the top of the Bunte Breccia before the emplacement of suevite. The high amount of basement clasts below suevite and on top of the underlying Bunte Breccia is consistent with the commonly reported inverse stratigraphy in the Ries impact structure. Graphical Abstract

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Geochemical studies of the SUBO 18 (Enkingen) drill core and other impact breccias from the Ries crater, Germany

Cited by 10 publications

References 61 publications

Heterogeneity of melts in impact deposits and implications for their origin (Ries suevite, Germany)

Heterogeneity of melts in impact deposits and implications for their origin (Ries suevite, Germany)

The Erbisberg drilling 2011: Implications for the structure and postimpact evolution of the inner ring of the Ries impact crater

Emplacement of shocked basement clasts during crater excavation in the Ries impact structure

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