TP 1

Mechanisms controlling major and trace element uptake during carbonate mineral formation and diagenetic alteration -
An experimental approach

Research Organization: Graz University of Technology
PI: Prof. Dr. M. Dietzel
Dr. V. Mavromatis, Dr D. Hippler
PhD Student: K. Götschl

The chemical and isotopic signatures of carbonate archives reflect the physicochemical parameters occurring during mineral formation and/or diagenetic transformation. Thus understanding the physicochemical parameters controlling the distribution of elemental and isotopic signals in carbonates are fundamental perquisites for the interpretation of the environmental conditions occurred during their formation and/or transformation. To date however the experimental studies that mechanistically describe reactions and pathways controlling such parameters are scarce.

The present project is focused on laboratory experiments for elemental/isotopic discrimination and nano/micro structural changes:

(i) Experimental alteration of selected carbonate samples will be performed at 20°C-resolution steps from 80 to 160 °C to provide together with the experiments conducted during Phase I a complete and higher resolved dataset on the chemical, isotopic and mineralogical changes occurring during diagenesis.

(ii) The experimental setup that was successfully developed in Phase I to study the precipitation mechanisms and kinetics of Amorphous Calcium Carbonate (ACC; Fig. 1) to crystalline calcium carbonate will be used in order to investigate the role of organic molecules during ACC stabilization and subsequent mineralization to CaCO3 and its impact on elemental and isotope proxies.

(iii) The formation of dolomite under low-T hydrothermal conditions will be studied under well-defined experimental conditions. This work will thus allow an in depth understanding of reaction mechanisms and pathways of low temperature carbonate (trans)formation at the presence of organic ligands and early diagenetic to hydrothermal dolomite formation which are both in terms of the main goals of CHARON.

To reach the above aims TP1 will use elemental (e.g., Mg, Sr, Ba) and isotopic signatures (e.g., δ44/42Ca, δ26/24Mg, δ88/86Sr, δ137/134Ba, δ34/32SO4 (CAS), clumped oxygen, δ18O as well as mineralogical and (micro)structural characterizations by strong cooperation with CHARON partners.

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