Environmental magnetism and magnetostratigraphy of plio-/peistocene sediments of the Heidelberger Becken.

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The Heidelberg Basin is considered to be in Neogene and Quaternary times the dominant sediment trap of the northern Upper Rhine Graben. Thus, it is regarded as a sedimentary achieve with a key role for the understanding of the tectonic, palaeogeographic and palaeoclimatic evolution of central Europe. During the past project duration detailed palaeomagnetic and rock magnetic investigations on drill cores from the Heidelberg Basin reaching up to 500 m depth were performed. The resultant consistent magnetic polarity stratigraphy of prevalent fluvial sediments provides the first independent chronostratigraphic time frame for those Pleistocene and younger Pliocene sequences (Scheidt et al. 2015). The ongoing rock magnetic analyses prove a complex magneto-mineralogy varying from iron sulphides dominated to iron-hydroxides controlled paragenesis. According to our working hypothesis iron sulphides are formed in the prevalent fluvial sediments during early diagenetic processes. A reducing interstitial environment triggered by synsedimentary water saturation was the underlying cause. These conditions prevailed from the beginning of the Pleistocene up to recent times. In contrast, periodical desiccation under dryer conditions led to a profound secondary oxidation of the Tertiary deposits. Under these conditions, diagenetic sulphides convert quantitatively to oxides and detrital components alter. During the Pleistocene, however, cooler and more humid environmental conditions associated with a modified hydrologic regime lead to a constant reducing diagenetic milieu. Thus, along with chemically buffering carbonate content a preservation of the diagenetically formed sulphides was possible. The focus of this renewal proposal is on the description of the magneto-mineralogical inventory, on the verification of the described genesis model and on the interpretation of the rock magnetic properties as a proxy for the climatic and environmental evolution. Furthermore, we envisage a reference study for rock magnetic investigations in fluvial sediments from temperate zones based on thorough magneto-mineralogical investigations. On the whole, we aim to a comprehensive and detailed rock magnetic analysis of Plio-/Pleistocene sedimentary successions situated in a key position for continent wide correlations.