What is it about?
In palaeoceanographic studies, chromium and aluminium find application as palaeoredox and palaeoproductivity indicators, respectively. This article discusses the association of Cr and Al in different carrier phases of the sediments. Using statistical methods, we have unravelled the factors that influence the partitioning and remobilization of Cr and Al from the sediments. Then, we discuss how the results obtained from this study can be useful to resolve the existing problems in oceanography.
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Why is it important?
One of the significant challenges in palaeoceanography is the reconstruction of palaeoproductivity and deducing the palaeoredox conditions. There are a myriad of proxies used for this purpose including CaCO3, opal, excess Al, carbon isotopes (13C/14C), redox-sensitive elements (U, Cr, V, and Mo), and several other proxies. However, the interpretations obtained using different proxies are not consistent. And, that poses problems in the interpretation of palaeoenvironmental conditions. Though bulk concentration Cr and Al got used as the indicators of palaeoenvironmental conditions, their use remains limited. In this study, we have shown that information about the partitioning of Cr and Al in different carrier phases can provide reliable information about palaeoredox and palaeoproductivity, respectively.
Perspectives
The bulk concentration of trace elements in the sediments is affected by several processes. However, their labile fraction in different carrier phases reveals the natural geochemical processes that brought such a change in their association and concentration. Each trace element is differently affected by pH and Eh. Thus, by studying the behaviour of different trace elements in different carrier phases, it should be possible to decipher the geochemical properties of the depositional environment. Here we have chosen the widely used proxies, the Al and Cr in our study. We have demonstrated that their labile fraction in different carrier phases is effective in addressing issues related to palaeoceanography. Researchers interested in furthering this work can read through the supplementary material that outlines specific areas in palaeoceanography where the particulate speciation of Cr and Al may find use.
Dr. ESWARAMOORTHI SELLAPPA GOUNDER
Curtin University
Read the Original
This page is a summary of: Palaeoenvironmental applications of chromium and aluminium: Concerns on partitioning and early diagenetic remobilization, Geological Journal, August 2020, Wiley,
DOI: 10.1002/gj.3913.
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