Mineralogy of marine sediment systems: A geochemical framework

Sediments are a major component of the ocean system and the composition of, and chemical processes acting upon, these sediments are controlled by many factors. In this chapter we outline the major types of marine sediment (lithogenous, biogenic, hydrogeneous and authigenic), discuss the sources of these and their chemical and mineral characteristics. The most abundant minerals are (oxyhydr)oxides, clay minerals, sulfides and carbonates, and all of these have been studied extensively, using a range of mineralogical techniques. A major aim of this chapter is to provide a framework by which the mineral transformations that take place upon, or just below, the sea-floor can be understood. There are significant thermodynamic, kinetic and biological controls on these transformations, and the interaction of these plays a major role in element cycling between the oceans and the lithosphere, and trace element-enrichment on the sea-floor and carbon burial and remineralization. Further, we conclude that more research is required on the interactions between minerals and bacteria within marine sediments, and on the role of amorphous oxide minerals delivered from land in early burial reactions and mineral precipitations.

Oceans cover ∼70% of the Earthâ∈™s surface so that the processes operating within the marine realm and upon ocean floors play a marked role in element and nutrient cycling, biological productivity, ultimately exerting an important influence on global climate. This chapter will focus on the distribution, composition and mineralogy of sediments that are actively accumulating on the sea floor, both in the shallow marine and deep ocean realms. Further, it will describe the geochemical and mineralogical processes operating in these sediments.