SedimentsSlide 2What do sediments look like?Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Classifying Sediment by Particle SizeSlide 12Sorting of sizes depends on the energy of the environmentTerrigenous SedimentsSlide 15Slide 16Slide 17Slide 18Biogenous SedimentsSlide 20Slide 21Slide 22Making Fossil FuelsHydrogenous SedimentsSlide 25Slide 26Cosmogenous SedimentsSlide 28Slide 29Slide 30Neritic and Pelagic SedimentsSlide 32Deep Ocean SedimentsSlide 34Slide 35Slide 36Slide 37Slide 38Slide 39Sampling SedimentsSlide 41Slide 42Slide 43Slide 44Slide 45Sediments as Historical RecordsSlide 47Slide 48Slide 49SedimentsSediment particles that accumulate in a loose, unconsolidated form.Originate fromweathering and erosion of rocksactivity of living organismsvolcanic eruptionschemical processes in the waterspaceBroad range of sizes and typesBeach sand is sedimentMud in quiet bays is sedimentWhat do sediments look like?•Surface–Could be smooth–May be rippled where there is a strong current•Color–Biological sediments are white or cream-colored–Clays range in color from tan to chocolate brown–Nearshore sediments are dark and contain organic matter and smell of hydrogen sulfide (rotten eggs)Classification by SourceClassifying Sediment by Particle Size•Particle size is used to classify sediments–Marine sediments are made of sand, silt and clay•The smaller the particle the more easily it can be transported by streams, waves and currents.•Transportation tends to sort sediments by size–Coarser grains tend not to travel as far as finer grains.–Clays may be transported great distancesSorting of sizes depends on the energy of the environment•Well-sorted :particles of one size –occur where energy fluctuates little•deep ocean sediments•Poorly-sorted: mixture of sizes –found where energy fluctuates a lot•rubble at the base of shore cliffTerrigenous Sediments•Most abundant –15 billion tons/year transported in rivers •100 million tons/year transported by air•Originate on continents or islands •Two most common components•granite, the source of quartz •clay, the of terrigenous sedimentsBiogenous Sediments•Next most abundant •Come from the living organisms–Plants and animals precipitate siliceous and calcareous compounds to form their shells and skeletons. –Most abundant in areas of high productivity•Continental Shelves–Over millions of years they can form oil and natural gasMaking Fossil FuelsHydrogenous Sediments•Minerals precipitate directly from water–sources •submerged rock and sediment•leaching of the fresh crust at oceanic ridges•material issuing from hydrothermal vents •substances flowing in river runoff–Called authigenic because they were formed in the place they currently occupy–Example: Manganese NodulesCosmogenous Sediments•Are of extraterrestrial origin and are the •Least abundant–Interplanetary dust •Silt and sand sized micrometeoroids that come from asteroids and comets or from collisions between asteroids–About 15,000 to 30,000 metric tons of interplanetary dust enters earth’s atmosphere every year–Rare impacts by large asteroids and comets•65 million years ago an asteroid 10 km in diameter struck earth on what is now the northern coast of the Yucatan.Global Sediment ThicknessSediments Distribution by SourceNeritic and Pelagic Sediments•Sediments on continental shelves are often different from those on basin floors–Continental shelf sediments, neritic sediments are primarily terrigenous •72% of all marine sediment is on continental slopes and rises–Deep ocean floors are covered by finer sediments than those of the continental margins.•Pelagic sediments come from the seaDeep Ocean Sediments•Thickness varies greatly from place to place–Atlantic = 1 km deep, Pacific = 0.5 km deep•Atlantic is smaller in area•Atlantic is fed by a greater number of rivers laden with sediment•Pacific has many trench that trap sediments moving toward basins–Sediments are thickest on the abyssal plains and thinnest (or absent) on ridges–Turbidites, Clays and OozesTurbiditesCalcium Carbonate Compensation Depth (CCD)Sampling Sediments•Historically sampled by clamshell samplers and deeper samples by piston corers–Pretty straightforward and dirtySediments as Historical Records•Stratigraphy - older sediments are below younger ones–Determine a historical record of events that happened in the distant past. –Analyze different layers, strata, in the sediments and determine what ocean conditions were when the sediments were laid down. •historical record of global climate or