Sediment biogenous

Biogenous sediment I I Foraminiferal muds Diatomaceous muds 1] Radiolarian-rich muds... 

Biogenous sediments Sediments that are composed of hard or soft parts, such as shells and tissues that were synthesized by marine organisms. 

Note that the observed concentrations of La and Th in seawater are in fact near the values expected from the solubility of phosphates (La and Th are effectively fixed as phosphates in almyrolithic exchanges between biogenic sediments and seawater), but the concentrations of the remaining elements are far lower than the values dictated by the solubility products. 

PRYOR (W.A.), 1975. Biogenic sedimentation and alteration of argillaceous sediments in shallow marine environments. Bull. Ceol. Soc. Amer. 

The Late Precambrian was characterized by an increase in the role of chemogenic and particularly of biogenic sedimentation. Deposition of iron-rich sediments was sharply curtailed, but thick piles of dolomite and limestone appeared, and the carbon content increased appreciably. 

Kawahata H., Suzuki A., and Ahagon N. (1998) Biogenic sediments in the West Caroline Basin and the western equatorial Pacific during the last 330,000 years. Mar. Geol. 149, 155-176. 

Lyle M., Murray D., Finney B., Dymond J., Robbins J., and Brookforce K. (1988) The record of Last Pleistocene biogenic sedimentation in the eastern tropical Pacific Ocean. Paleoceanography 3, 39-59. 

Rea D., Pisias N., and Newberry T. (1991) Late Pleistocene paleoclimatology of the central equatorial Pacific flux patterns of biogenic sediments. Paleoceanography 6, 227-244. 

Thunell R. C., Miao Q., Calvert S. E., and Pederson T. F. (1992) Glacial-Holocene biogenic sedimentation patters in... 

In this chapter we first outlined a conceptual model for the relationship between primary geological processes involved in the formation of fine-grained, siliciclastic-biogenic sediments and sedimentary rocks and a selected set of... 

Murray R. W. and Leinen M. (1996) Scavenged excess aluminum and its relationship to bulk titanium in biogenic sediment from the central Equatorial Pacific Ocean. Geochim. Cosmochim. Acta 60, 3869-3878. 

Carbonate and opaline-silica-rich sediments are exceptions to these generalizations. They are very low in detrital iron, because calcareous and siliceous skeletal debris is much lower in iron than terrigenous material. In these dominantly biogenic sediments, iron may become limiting the degree of pyritization is very high (>80%) and... 

Efforts to find trace-metal evidence of extraterrestrial impact at the Ordovician-Silurian boundary have been unsuccessful (e.g., Orth et al, 1986 Wang et al, 1992). Peaks in iridium abundance at the boundary have been linked to reductions in sedimentation rate the persistent cosmic source of iridium is otherwise diluted by high terrigenous or biogenic sedimentation. 

Solids eroded from the continental surface account for about 80% of the material mass transport (Table 3). Most of the solid material flux, about 95% of it, is carried by water discharge and the remaining 5% are transported by winds. The total suspended material load of rivers and the dust load of the atmosphere include products of the bedrock erosion as well as materials eroded from clastic and biogenic sediments exposed on the continents. Equating the sum of the riverine and atmospheric transport fluxes of solids with the rate of continental erosion or mechanical denudation implies that a part of the eroded mass that is stored in clastic sediments on land remains constant (Fig. 4) ... 

Inorganic sediment is supplied by erosion of material from exposed areas of high relief, and can be transported a considerable distance to the area of deposition. The composition of this detrital (or clastic) material varies, but aluminosilicate minerals are usually important. There are also biogenic sediments, resulting from the remains of organisms (e.g. calcareous and siliceous tests, peat) and chemical sediments formed by precipitation of minerals from solution (e.g. evaporites, some limestones and authi-genic infills of pores by quartz and calcite cements). 

Biogenous sediments generally refer to bioclastic sediments, hence sediments which are built of remnants and fragments of shells and tests produced by organisms - calcareous, siliceous or... 

Table 1.2 Major groups of marine organisms contributing to biogenic sediment formation and mineralogy of skeletal hard parts. Foraminifera and diatoms (underlined) are important groups of both plankton and benthos, x = common, (x) = rare (mainly after Fliigel 1978, 2004 and Milliman 1974).

Biogenic sediments with coarse-grained calcareous sediments predominate at lower latitudes, Detrital sediments with riverine terrigenous siliciclastic material at moderate latitudes, and... 

Examples from terrigenous and biogenic sedimentation provinces are presented (1) to illustrate the large variability of physical properties in different sediment types and (2) to establish a sediment classification which is only based on physical properties, in contrast to geological sediment classifications which mainly uses parameters like grain size distribution or mineralogical composition (Sect. 2.5). 

Finally, some examples from high-resolution narrow-beam echosounder recordings present remote sensing images of terrigenous and biogenic sedimentation enviromnents (Sect. 2.6). 

As the acoustic properties of water-saturated sediments are strongly controlled by the amount and distribution of pore space, cross plots of P-wave velocity and attenuation coefficient versus porosity clearly indicate the different bulk and elastic properties of terrigenous and biogenic sediments and can thus be used for an acoustic classification of the lithology. Additional S-wave velocities (and attenuation coefficients) and elastic moduli estimated by least-square inversion specify the amount of bulk and shear moduli which contribute to the P-wave velocity (Breitzke 2000). 

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