Lithology and diagenesis of the poorly consolidated Cambrian siliciclastic sediments in the northern Baltic Sedimentary Basin

The present study discusses lithology and diagenetic characteristics of the siliciclastic Cambrian and the enclosing Ediacaran and Ordovician deposits in the northern Baltic Sedimentary Basin (BSB). The Neoproterozoic and Lower Palaeozoic sediments are despite their age unconsolidated with primary porosity of 20-25% for both shales and sandstones. The sparse Fe-dolomite cementation of arenitic and subarenitic sandstones and siltstones occurs mainly at lithological contacts with the massive Ediacaran and Lower Cambrian claystones and is probably related to ions released during llitization. In contrast to weak mechanical and chemical compaction of sandstone, the clay mineral diagenesis of Cambrian deposits is well advanced. The highly illitic (80-90%) nature of illite-smectite (I-S) suggests evolved diagenetic grade of sediments which conflicts with shallow maximum burial and low compaction. Smectite-to-illite transformation has resulted in formation of diagenetic Fe-rich chlorite in claystones. Some porosity reduction of sandstones is due to formation of authigenic kaolinite at the expense of detrital mica or K-feldspar

Impact into a Graphite-Bearing Regolith: A Dynamic Shock Recovery Study

Mercury’s surface is exposed to a multitude of surface altering effects that have a significant influence on its optical properties. Impact events – small or large – are one of the major surface-altering agents. Inferred from hypothetical modal abundances [1] graphite can comprise up to 4 wt% on Mercury’s surface. Graphite as a possible stable phase on Mercury can explain the relatively low albedo of the planet [2]. Our experimental setup probes the hypothetical impact into a graphite- and olivine-bearing, pyroxene-rich (Px (En87) = 68 wt%; Ol (Fo91) = 29 wt%, C = 3 wt%) surface. The effect of post-shock heating and pressure on a powder comprised of silicates with grain sizes ≤125 μm and hexagonal graphite was simulated in a classic shock recovery experiment [3]. The experiments were performed in the framework of the BepiColombo mission to Mercury. The onboard Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) will send thermal emissivity data once it reaches the Hermean orbit in 2025. A spectral database for mid infrared data is currently set up at the Institut für Planetologie in Münster. Published mid infrared data will soon be available and sample related spectral information of interest can be traced via assigned IDs (e.g., IDxxx)