TY - JOUR A1 - Reimold, Wolf Uwe A1 - Fischer, Luise A1 - Müller, Jan A1 - Kenkmann, Thomas A1 - Schmitt, Ralf-Thomas A1 - Altenberger, Uwe A1 - Kowitz, Astrid T1 - Impact-generated pseudotachylitic breccia in drill core BH-5 Hattberg, Siljan impact structure, Sweden JF - GFF N2 - Pseudotachylitic breccia (PTB) in the form of cm-wide melt breccia veinlets locally occurs on the exposed central uplift of the 380Ma Siljan impact structure. The host rock to the PTBs is the so-called Jarna granite of quartz monzonitic to syenodioritic composition. The nearly 603m long BH-5 drill core from Hattberg, near the centre of the Siljan central uplift, contains numerous veins and pods of PTB. In particular, two major zones of 60m combined width contain extensive PTB network breccias (30% actual melt breccia component), with individual melt breccia occurrences up to >1m in length. Core logging and petrographic and geochemical analysis of the core have been performed, and the data are interpreted to suggest the following. (1) The impact event caused low to moderate (at essentially <20GPa) shock deformation in the host rock and in clasts of this lithology within the PTB. (2) Macroscopic deformation of the basement mainly comprises fracturing, with only localised cataclasis. (3) No evidence for shock melting (i.e. compression/decompression melting early in the cratering process) could be observed. (4) Optical and scanning electron microscopy showed that dark PTB contains a definite melt component. (5) Shearing has significantly affected this part of the central uplift, but its effects are limited to very short displacements and likely did not result in extensive melting. (6) A frictional heating component upon melt generation can, however, not be excluded, as many PTB samples contain clasts of a mafic (gabbroic) component, although only in one place along the entire core, a 1.2cm-wide section through such material in direct contact to host rock was observed. Consequently, we suggest that, upon uplift in the central part of the impact structure, considerable melt volumes were generated locally, especially in areas that had been affected by extensive cataclasis and where grain size comminution favoured melt formation. Rapid decompression related to central uplift formation is the preferred process for the generation of the PTB melt breccias. Y1 - 2015 U6 - https://doi.org/10.1080/11035897.2015.1015264 SN - 1103-5897 SN - 2000-0863 VL - 137 IS - 2 SP - 141 EP - 162 PB - Routledge, Taylor & Francis Group CY - Abingdon ER - TY - JOUR A1 - Bösche, Nina Kristine A1 - Rogass, Christian A1 - Lubitz, Christin A1 - Brell, Maximilian A1 - Herrmann, Sabrina A1 - Mielke, Christian A1 - Tonn, Sabine A1 - Appelt, Oona A1 - Altenberger, Uwe A1 - Kaufmann, Hermann T1 - Hyperspectral REE (Rare Earth Element) Mapping of Outcrops-Applications for Neodymium Detection JF - Remote sensing N2 - In this study, an in situ application for identifying neodymium (Nd) enriched surface materials that uses multitemporal hyperspectral images is presented (HySpex sensor). Because of the narrow shape and shallow absorption depth of the neodymium absorption feature, a method was developed for enhancing and extracting the necessary information for neodymium from image spectra, even under illumination conditions that are not optimal. For this purpose, the two following approaches were developed: (1) reducing noise and analyzing changing illumination conditions by averaging multitemporal image scenes and (2) enhancing the depth of the desired absorption band by deconvolving every image spectrum with a Gaussian curve while the rest of the spectrum remains unchanged (Richardson-Lucy deconvolution). To evaluate these findings, nine field samples from the Fen complex in Norway were analyzed using handheld X-ray fluorescence devices and by conducting detailed laboratory-based geochemical rare earth element determinations. The result is a qualitative outcrop map that highlights zones that are enriched in neodymium. To reduce the influences of non-optimal illumination, particularly at the studied site, a minimum of seven single acquisitions is required. Sharpening the neodymium absorption band allows for robust mapping, even at the outer zones of enrichment. From the geochemical investigations, we found that iron oxides decrease the applicability of the method. However, iron-related absorption bands can be used as secondary indicators for sulfidic ore zones that are mainly enriched with rare earth elements. In summary, we found that hyperspectral spectroscopy is a noninvasive, fast and cost-saving method for determining neodymium at outcrop surfaces. Y1 - 2015 U6 - https://doi.org/10.3390/rs70505160 SN - 2072-4292 VL - 7 IS - 5 SP - 5160 EP - 5186 PB - MDPI CY - Basel ER -