FOR 1644 Subproject - Unraveling the sulfur cycle with carbonates: mechanism of incorporation and diagenesis of structurally-substituted-sulfate (CHARON)

Basic data for this project

Description

Marine carbonates represent the central archive for reconstructing Earth System evolution in respect to the physical and chemical characteristics of the oceans as well as changes in atmospheric composition and global climate. Biogenic carbonates, carbonate cements and micrites alike have been utilized for reconstructing respective seawater properties. Aside more classical isotopic proxies such as carbon, oxygen, or strontium, an increasing number of studies utilizes trace quantities of sulfate in order to reconstruct the sulfur isotopic composition of seawater sulfate through time. Even more, individual studies interpreted the amount of extracted sulfate as a reflection of the initial oceanic sulfate abundance. Although empirical evidence suggests that the sulfur isotopic composition indeed reflects the isotopic composition of oceanic sulfate at the time of carbonate deposition, no firm understanding about the mechanism of as well as the boundary conditions for sulfate incorporation exists. Furthermore, carbonates are subject to post-depositional diagenetic alteration. Yet, respective effects on the abundance and isotopic composition of this trace constituent in carbonates are largely unknown. Experimental and empirical work proposed here aims at unravelling respective details of sulfate incorporation and its post-depositional alteration in order to place firm constraints on the applicability as a proxy for reconstructing Earth System evolution.