Rock alteration at the post-Variscan nonconformity: implications for Carboniferous–Permian surface weathering versus burial diagenesis and paleoclimate evaluation

Abstract. A nonconformity refers to a hiatal surface located between metamorphic or igneous rocks and overlying sedimentary volcanic rocks. These surfaces are key features with respect understanding the relations among climate, lithosphere tectonic movements during ancient times. In this study, petrological, mineralogical geochemical characteristics of Variscan basement rock as well its Permian volcano-sedimentary succession from drill core in Sprendlinger Horst, Germany, analyzed by means polarization microscopy, environmental scanning electron microscope, X-Ray diffraction, X-ray fluorescence inductively coupled plasma mass spectrometry analyses. gabbroic diorite basement, intensity micro- macro-fractures increases towards top, indicating an intense physical weathering. The is basaltic andesite that shows less weathering compared diorite. both segments, secondary minerals dominated illite mixed-layer phase smectite (I–S). corrected chemical index alteration (CIA) plagioclase (PIA) indicate intermediate unweathered degree extreme andesite. τ values for abnormal enrichment K, Rb Cs cannot be observed Accompanying such adularia suggest subsequent overprint (K-rich) fluids burial diagenesis which promoted conversion illite. overall order element depletion process follows: large-ion lithophile elements (LILEs) > rare earth (REEs) high-field-strength (HFSEs). Concerning REEs, heavy (HREEs) depleted than light (LREEs). Our study supergene paleo-weathering conserved at post-Variscan despite hypogene alteration. Both can distinguished characteristic indices. Based on these results, new workflow eliminate distractions paleoclimate evaluation evolution developed.