Traces of Fallback Breccia on the Rim of Barringer Meteorite Crater (a.k.a. Meteor Crater), Arizona

Barringer Meteorite Crater (a.k.a. Meteor Crater), Arizona, is one of the youngest and best preserved impact craters on Earth. For that rea-son, it provides a baseline for similar craters formed in the geologic past, formed elsewhere in the Solar Sys-tem, and illuminates the astronomical and geological processes that produce them. The crater has not, how-ever, escaped erosion completely. While Shoemaker [1] mapped a breccia with fallback components inside the crater, he did not locate it beyond the crater rim. He only found remnants of that type of debris in re-worked alluvium [1; see also 2]. Fallback breccia and any base-surge deposits have, thus, been missing components in studies of material ejected beyond the transient crater rim

Shaping of the Present-Day Deep Biosphere at Chicxulub by the Impact Catastrophe That Ended the Cretaceous

We report on the effect of the end-Cretaceous impact event on the present-day deep microbial biosphere at the impact site. IODP-ICDP Expedition 364 drilled into the peak ring of the Chicxulub crater, México, allowing us to investigate the microbial communities within this structure. Increased cell biomass was found in the impact suevite, which was deposited within the first few hours of the Cenozoic, demonstrating that the impact produced a new lithological horizon that caused a long-term improvement in deep subsurface colonization potential. In the biologically impoverished granitic rocks, we observed increased cell abundances at impact-induced geological interfaces, that can be attributed to the nutritionally diverse substrates and/or elevated fluid flow. 16S rRNA gene amplicon sequencing revealed taxonomically distinct microbial communities in each crater lithology. These observations show that the impact caused geological deformation that continues to shape the deep subsurface biosphere at Chicxulub in the present day

Globally distributed iridium layer preserved within the Chicxulub impact structure

The Cretaceous-Paleogene (K-Pg) mass extinction is marked globally by elevated concentrations of iridium, emplaced by a hypervelocity impact event 66 million years ago. Here, we report new data from four independent laboratories that reveal a positive iridium anomaly within the peak-ring sequence of the Chicxulub impact structure, in drill core recovered by IODP-ICDP Expedition 364. The highest concentration of ultrafine meteoritic matter occurs in the post-impact sediments that cover the crater peak ring, just below the lowermost Danian pelagic limestone. Within years to decades after the impact event, this part of the Chicxulub impact basin returned to a relatively low-energy depositional environment, recording in unprecedented detail the recovery of life during the succeeding millennia. The iridium layer provides a key temporal horizon precisely linking Chicxulub to K-Pg boundary sections worldwide

Non-traditional stable isotope variations on the impactites of the Rochechouart impact structure : tracing impact volatilization, melting, mixing and hydrothermal overprinting

International audienc

A new age model and chemostratigraphic framework for the Maastrichtian type area (southeastern Netherlands, northeastern Belgium)

The youngest time interval of the Cretaceous Period is known as the Maastrichtian, in reference to the shallow-marine strata outcropping in the area surrounding the city of Maastricht, in the Netherlands-Belgium border region. While the type-Maastrichtian strata have yielded a wealth of paleontological data, comparatively little geochemical work has so far been carried out on this succession. To date, age assessment of the type-Maastrichtian, and stratigraphic correlation with sections elsewhere, have largely been based on biostratigraphy and preliminary attempts at cyclostratigraphy. However, these techniques are hampered by bio-provincialism and the presence of stratigraphic gaps in the succession, respectively. In recent years, stable carbon isotope stratigraphy has proven to be a powerful tool for correlating Upper Cretaceous strata on a global scale. When integrated with biostratigraphy, carbon isotope stratigraphy can be used to test the synchroneity of biological and climatic events across the globe and to reconcile inter-regional biostratigraphic schemes. Therefore, we have generated the first high-resolution bulk stable carbon isotope stratigraphy for the type-Maastrichtian, using an extensive sample set acquired within the context of the Maastrichtian Geoheritage Project spanning approximately 100 meters of stratigraphy at the Hallembaye and former ENCI quarries. In combination with bulk major and trace element data generated using µXRF, this record presents the first high-resolution chemostratigraphic survey for the type-Maastrichtian. The µXRF-based element profiles through the type-Maastrichtian succession reveal variable fluxes of terrigenous input into this carbonate system over time, marking three distinct stratigraphic sequences, separated by sequence boundaries at the Froidmont, Lichtenberg and Vroenhoven horizons. In addition, the carbon isotope profile records the Campanian–Maastrichtian Boundary Event (CMBE) and the Mid-Maastrichtian Event (MME) in the Maastrichtian type area for the first time. Our refined age model allows for global correlation between the type-Maastrichtian sequence and Maastrichtian successions worldwide and places the abundant paleontological records from the type-Maastrichtian in a global context

Optimizing multiple non-invasive techniques (PXRF, pMS, IA) to characterize coarse-grained igneous rocks used as building stones

We present a workflow to conduct a full characterization of medium to coarse-grained igneous rocks, using portable, non-invasive, and reproducible approaches. This includes: (i) Image Analysis (IA) to quantify mineral phase proportions, grain size distribution using the Weka trainable machine learning algorithm. (ii) Portable X-ray fluorescence spectrometer (PXRF, Bruker Tracer IV) to quantify the whole-rock's chemical composition. For this purpose, a specific calibration method dedicated to igneous rocks using the open-source CloudCal app was developed. It was then validated for several key elements (Si, Al, K, Ti, Ca, Fe, Mn, Sr, Ga, Ba, Rb, Zn, Nb, Zr, and Y) by analyzing certified standard reference igneous rocks. (iii) Portable Magnetic Susceptibilimeter (pMS, Bartington MS2K system) to constrain the mineralogical contribution of the samples. The operational conditions for these three methods were tested and optimized by analyzing five unprepared surfaces of igneous rocks ranging from a coarse-grained alkaline granite to a fine-grained porphyric diorite and hence, covering variable grain sizes, mineralogical contents, and whole-rock geochemical compositions. For pMS and PXRF tools, one hundred analyses were conducted as a 10 cm × 10 cm square grid on each sample. Bootstrap analysis was implemented to establish the best grid size sampling to reach an optimized reproducibility of the whole-rock signature. For PXRF analysis, averaged compositions were compared to PXRF analysis on press-pellets and laboratory WD-XRF analysis on fused disk and solution ICP-OES (for major) and solution-ICPMS (for trace element concentrations). Ultimately, this workflow was applied in the field on granitoids from three Roman quarrying sites in the Lavezzi archipelago (southern Corsica) and tested against the Bonifacio granitic War Memorial, for which its provenance is established. Our results confirm this information and open the door to geoarchaeological provenance studies with a high spatial resolution.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Micro-X-ray fluorescence elemental data of the shell of A. benedeni benedeni specimens SG-125, SG-126, and SG-127

This dataset (XRF_Benedeni_benedeni_SG-125_126_127_crosslines_cal.csv) contains micro-X-ray fluorescence elemental data of the shell of A. benedeni benedeni specimens SG-125, SG-126, and SG-127. The bivalve shells were collected in 2013 from a shell bed at the top of the Oorderen Member of the Lillo Formation of the Pliocene in Belgium. The collection site was a construction-related temporary outcrop at the Deurganck Dock Lock (now Kieldrecht Lock) in the city of Antwerp, located at 51°16′44″N 4°14′52″E. These measurements were carried out in order to screen for diagenetic alteration, which results in enrichment of certain elements (e.g., Fe and Mn). The specimens were measured in spring 2021 at the Analytical, Environmental, and Geochemistry Research Group (AMGC) of the Vrije Universiteit Brussel, Belgium), on a Bruker M4 Tornado µXRF scanner. This instrument is equipped with a 30 W Rh anode metal-ceramic X-ray tube operated at 50 kV and 600 µA, and polycapillary lens focussing. The measurement was carried out following the methods described in de Winter and Claeys (2017) and Kaskes et al (2021), and consisted of multiple line scans oriented perpendicular to the growth direction. Also provided is an image file (XRF_Benedeni_benedeni_crosslines_locations.png) which shows the location of these line scans on the shell cross sections

Electron backscatter diffraction maps of thin sections of A. benedeni benedeni specimens SG-125, SG-126, and SG-127

This dataset (.crc and .cpr files) contain electron backscatter diffraction maps of thin sections of A. benedeni benedeni specimens SG-125, SG-126, and SG-127. Also included are .BMP files for each map. The bivalve shells were collected in 2013 from a shell bed at the top of the Oorderen Member of the Lillo Formation of the Pliocene in Belgium. The collection site was a construction-related temporary outcrop at the Deurganck Dock Lock (now Kieldrecht Lock) in the city of Antwerp, located at 51°16′44″N 4°14′52″E. These measurements were carried out in order to determine the microstructures of the shells of A. benedeni benedeni, as well as to screen for minor diagenetic alterations. The specimens were measured in spring 2021 at Department of Earth Sciences of Utrecht University, the Netherlands, on an Oxford Instruments Symmetry EBSD detector attached to a Zeiss Gemini 450 SEM. Thin sections of the samples were mechanically polished with 0.3 µm aluminium oxide suspension and finished with chemical Syton® polish. The thin sections were covered with a thin (several nm) carbon coating to keep charge build-up during the measurements at a minimum