Alex Deutsch’s research while affiliated with University of Münster and other places

... Quartz grains with shock metamorphic features, commonly referred to as "shocked quartz," are a typical diagnostic criterion used for the identification of hypervelocity impact structures on Earth (e.g., Stöffler and Langenhorst 1994;Grieve et al. 1996;French 1998;French and Koeberl 2010;Deutsch et al. 2015;Stöffler et al. 2017;and references therein). In addition to the simple optical properties of quartz and its natural abundance in terrestrial crustal rocks, its shock metamorphic features, forming at a wide pressure range, are well characterized. ...

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Characterization of shocked quartz grains from Chicxulub peak ring granites and shock pressure estimates

... The ∼200 km wide Chicxulub impact structure in México, formed by a hypervelocity impact event ∼66 Myr ago, constitutes a natural laboratory to examine the response of distinct lithological units to extreme shock conditions (1)(2)(3)(4)(5)(6). Constraining the rapid temperature changes that target rocks experience during and after impact cratering events remains extremely challenging due to generally poorly preserved impact lithologies and the complexities of reconstructing high-temperature conditions in a laboratory setting (7,8). Over the last 15 years, carbonate clumped-isotope thermometry has increasingly been used to reconstruct absolute temperatures in the geological record, based on measurements of the abundance of 13 C- 18 O bonds in lattices of carbonate minerals, expressed as Δ 47 (9). ...

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Hot carbonates deep within the Chicxulub impact structure

... Hypervelocity impacts are extremely complicated geologic processes that have been studied by experiments (e.g., Housen & Holsapple, 2011;Kenkmann et al., 2018) and sophisticated numerical simulations (e.g., Collins et al., 2012). Senft and Stewart (2008) derived the equation-of-state and strength model parameters for H 2 O and modeled impacts into an icy-layer underlain by a rocky target. ...

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Ray and Halo Impact Craters on Ganymede: Fingerprint for Decoding Ganymede's Crustal Structure

... This iron, immiscible with the silicate melt, separates as liquid metallic droplets. These droplets, rich in iron, disperse from the silicate melt, and earlyseparated droplets may coalesce into larger ones to minimize surface energy, resulting in np-Fe particles of varying sizes [39,47]. The chemical reaction involved can be expressed as ...

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The Formation Mechanisms of np-Fe in Lunar Regolith: A Review

... On Earth and other celestial bodies, craters with diameters of several hundred meters up to a few kilometers represent a very common feature. In general they can be formed by meteorite impacts (Osinski and Pierazzo, 2013;Kenkmann et al., 2014Kenkmann et al., , 2017 or by explosive volcanism Geomorphology 367 (2020) 107297 (White and Ross, 2011). However, since crater rims may be more or less eroded and the sedimentary infill of the crater is often not well exposed, the morphological features alone may not be indicative for their origin, which leads often to a certain controversy regarding the possible formation scenarios. ...

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The formation of a giant collapse caprock sinkhole on the Barda Negra plateau basalts (Argentina): Magnetic, mineralogical and morphostructural evidences. GEOMORPHOLOGY 367 ; 15 October 2020

... By fitting our data to Equation 2, our results (the dashed black line with black dots in Figure 4) show a gentler slope (d = 3.09; c = 2.37 × 10 −3 ) than the analytical value. This is partially caused by the decreasing influence of the porosity gradient with increasing projectile size L. To demonstrate the significance of porosity, we conducted iSALE simulations without any target porosity (all other parameters are identical), where the critical shock pressure for melting is assumed to be 60 GPa (Hamann et al., 2016). The results (Figure 4b) show that the relative enhancement of melt abundance gradually increases with decreasing crater size, which corresponds to an increasing influence of the more porous target toward the shallowest strata ( Figure 1). ...

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Melt Production and Ejection From Lunar Intermediate‐Sized Impact Craters: Where Is the Molten Material Deposited?

... The highly shocked ejecta particles recovered from MEMIN impact experiment A20-5339 (Fig. 1e) were described in detail by Ebert et al. (2014). They are white-to dark-gray composite particles composed of Fig. 1f and Ebert et al. 2015); the images are from LE-I. a, b) Three different silicate emulsion zones between a piece of Campo del Cielo (the projectile piece plucked out during sectioning and polishing) and sandstone target melts. ...

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Silicate liquid immiscibility in impact melts

... Other instrumentation, such as laser ablation (LA) ICP-MS would yield better detection limits, although NanoSIMS may be the instrument of choice considering their sizes observed in this study. Although most baddeleyite compositional studies in the literature do not include REEs, a few have reported REEs using either EPMA (e.g., Rajesh et al., 2006;Tropper et al., 2007;Huraiová et al., 2011;Zhao et al., 2016) or LA-ICP-MS (e.g., Schärer et al., 2011;Zhang et al., 2017) techniques. In all cases, the REE content is very minor, ≤ 1 wt %-1.5 wt %. ...

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Zirconium-bearing accessory minerals in UK Paleogene granites: textural, compositional, and paragenetic relationships

... Despite the indirect evidence raised to date that points towards an exogenous origin for the Colônia structure due to a meteorite impact, there are no scientifically accepted direct evidences of this phenomenon. Based on the analysis of samples from drilling for groundwater wells inside the structure, VELÁZQUEZ et al. (2013VELÁZQUEZ et al. ( , 2018VELÁZQUEZ et al. ( , 2021 presented supposed evidence in this regard that does not stand up to the literature (e.g., REIMOLD et al. 2014, CRÓSTA & REIMOLD 2016, CRÓSTA et al. 2019a). The only "evidence" of shock micro-deformation presented by VELÁZQUEZ et al. (2013) is the supposed occurrence of PDFs in quartz; despite the low quality of the illustration presented for this feature, it is possible to infer that it does not correspond to true PDF and probably results from a typical tectonic deformation event of the local basement rocks and, therefore, from a pressure regime well below the shock regime. ...

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GEOLOGICAL RECORDS OF METEORITIC IMPACTS IN BRAZIL: EVOLUTION AND CURRENT KNOWLEDGE

... Cratering experiments in solid rocks have been conducted for a broad range of target, projectile and velocity conditions by Shoemaker et al. (1963), Gault and Greeley (1978), Polanskey and Ahrens (1990), Love et al. (1993, Housen and Holsapple (2003), Burchell and Whitehorn (2003), and Ai and Ahrens (2004). Recently, a large number of impact experiments into solid rocks have been conducted in the framework of the MEMIN (Multidisciplinary Experimental and Modeling Impact Research Network) program (Kenkmann et al. 2011Kenkmann et al. , 2013 Poelchau et al. 2013). Such experiments are suited to investigate the deformation inventory of the crater subsurface (Maurer and Rinehart 1960; Kenkmann et al. 2011; Onose et al. 2011; Buhl et al. 2013a Buhl et al. , 2013b), and also to search for shatter cones and to constrain the formation conditions (Shoemaker et al. 1961; Moore et al. 1962; Schneider and Wagner 1976; Roddy and Davis 1977; Kenkmann et al. 2012). ...

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Formation of shatter cones in MEMIN Impact experiments