70 SEDIMENTARY ROCKS/Deep Ocean Pelagic Oozes Further Reading Bjørlykke K (1998) Clay mineral diagenesis in sedi mentary basins a key to the prediction of rock pro perties Examples from the North Sea Clay Minerals 33: 15 34 Burley SD and MacQuaker JHS (1992) Authigenic clays, diagenetic sequences and conceptual diagenetic models in contrasting basin margin and basin centre North Sea Jur assic sandstones and mudstones In: Houseknecht DW and Pittman ED (eds.) Origin, Diagenesis and Petrophy sics of Clay Minerals in Sandstones, Society of Economic Paleontologists and Mineralogists Special Publication 47, pp 81 110 Tulsa, OK: Society of Economic Paleontolo gists and Mineralogists Ehrenberg SN and Nadeau PH (1989) Formation of diagenetic illite in sandstones of the Garn Formation, Haltenbanken area, mid Norwegian continental shelf Clay Minerals 24: 233 253 Hower J, Eslinger EV, Hower ME, and Perry EA (1976) Mechanism of burial metamorphism of argil laceous sediments: 1: Mineralogical and chemical evi dence Geological Society of America Bulletin 87: 725 737 Huggett JM (1995) Formation of authigenic illite in Palaeo cene mudrocks from the central North Sea: a study by high resolution electron microscopy Clays and Clay Minerals 43: 682 692 Huggett JM (1996) Aluminosilicate diagenesis in a Tertiary sandstone mudrock sequence from the central North Sea, U.K Clay Minerals 31: 523 536 Kisch HJ (1990) Calibration of the anchizone: a critical comparison of illite ‘crystallinity’ scales used for defin ition Journal of Metamorphic Geology 8: 31 46 Lanson B, Beaufort D, Berger G, Bauer A, Cassagnabere, and Meunier A (2002) Authigenic kaolin and illitic minerals during burial diagenesis of sandstones: a review Clay Minerals 37: 22 Longstaffe F (1989) Stable isotopes as tracers in clastic diagenesis In: Hutcheon IE (ed.) Short Course in Burial Diagenesis, pp 201 277 Toronto: Mineralogical Association of Canada Nadeau PH, Wilson MJ, McHardy WJ, and Tait J (1984) Interstratified clays as fundamental particles Science 225: 923 925 Pollastro R (1993) Considerations and applications of the illite/smectite geothermometer in hydrocarbon bearing rocks of Miocene to Mississippian age Clays and Clay Minerals 41: 119 133 Srodon J (1999) Use of clay minerals in reconstructing geological processes: recent advances and some perspec tives Clay Minerals 34: 27 38 Deep Ocean Pelagic Oozes R G Rothwell, Southampton Oceanography Centre, Southampton, UK ß 2005, Elsevier Ltd All Rights Reserved Introduction Deep-ocean pelagic (from the Greek pelagios, meaning ‘of the sea’) sediments are areally and volumetrically the dominant sediment type found on the ocean floor They comprise three main types, depending on their primary composition: deep-sea siliceous oozes, calcareous oozes, and deep-water red clays (Figure 1) Pelagic sediments mixed with terrigenous material derived from continental weathering are termed ‘hemipelagic’ Siliceous and calcareous oozes are composed largely of test and test debris of planktonic micro-organisms such as foraminifera, coccolithophores, pteropods, diatoms, and radiolaria The formation of pelagic sediments involves settling of material, that is commonly derived from biological surface productivity, but also includes wind-derived material that travels through the water column (‘pelagic rain’) to the seafloor (Figure 2) This process occurs throughout the world’s oceans and true pelagic deposits tend to blanket seafloor topography Local remobilization of pelagic sediments on topographic highs due to slope instability may result in pelagic turbidites (redeposited units) that pond in adjacent lows However, the distribution of pelagic sediments is strongly depth controlled, because calcium carbonate shows increasing solubility with depth In contrast to terrigenous sediments (the other main type of deep-sea sediment, largely composed of detrital material derived from continental weathering), pelagic sediments are characterized by low sedimentation rates and frequently contain a high proportion of authigenic minerals, extraterrestrial material, and, where physicochemical conditions allow, a substantial biogenic component History of Research Although mention of marine sediments has found in Greek and Roman texts, it was not 1773 that the recovery of sediment from the sea was first recorded In that year, Captain been until deep John