Sources and Composition of Marine Sediments

Abstract

Marine sediments consist of deposits accumulating below the sea. They show great variety. There is the debris from the wearing down of continents and volcanic mountains, the shells derived from organisms, organic matter, minerals precipitated from seawater, and there are volcanic products such as ash and pumice. All such matter is transported in various ways, is deposited, and subsequently suffers diagenesis and redeposition to various degrees (Fig. 4.1). Terrigenous muds (with their tremendous fraction of continental erosion products) make up well over one half of the total volume of marine deposits. By area it is deep-sea sediments that are dominant, with roughly one half of the deep seafloor covered by calcareous ooze – largely shell material from coccolithophores and foraminifers, along with some reef debris along many tropical margins. In contrast, extraterrestrial matter, while interesting for its content of information, is negligible when considering abundance.