Sediments On The Sea Floor

2y ago
9 Views
2 Downloads
971.15 KB
12 Pages
Last View : 1m ago
Last Download : 2m ago
Upload by : Kairi Hasson
Transcription

Sediments on the Sea FloorWhy is the sediment on the oceanic crust thicker nearthe continents?1SedimentsBased on datafrom coresamples,scientists havedetermined theage of portions ofthe Pacific floor,measured inmega-annums, ormillions of years.21

Deep-Ocean BasinsIsland Arcs - chains of volcanic islands andseamounts, usually found parallel to the edges ofocean trenches.As two oceanic plates converge, an island arc isformed by volcanic activity.3Studying Sediments: Key Ideas Ocean sediment includes particles from land, biological activity,chemical processes and space. Ocean sediment is thickest over continental margins and thinnestover active oceanic ridges. Sediment deposited on a quiet seafloor can provide a sequentialrecord of recent events in the water column above. Sediments arerecycled into earth at subduction zones. Sediments are an important source of crude oil and natural gas.42

Studying Sediments Deep-water Clamshell PistoncamerassamplersCorers SeismicprofilersWhat can we learn by studying sediments? Historical information Location of natural resources, especially crude oil and naturalgas5Classification of Marine Sediments: Size orOrigin.Size classification divides sediment by grain size intogravel, sand, silt and clay.Mud is a mixture of silt and clay.Origin classification divides sediment into fivecategories: terrigenous, biogenic, authigenic,volcanogenic and cosmogenic sediments.63

Classifying SedimentSediment can be classified by particle size. Waves and currentsgenerally transport smaller particles farther than larger particles.7Table 3.184

Comparison of Poorly-Sorted and Well-Sorted Sediments9Factors that Control Sedimentation: Source,Particle Size, TurbulenceTerrigenous sediments strongly reflect theirsource and are transported to the sea by wind,rivers and glaciers.Average grain size reflects the energy of thedepositional environment.105

Hjulstrom’s DiagramHjulstrom’s Diagram graphs the relationshipbetween particle size and energy for erosion,transportation and deposition.Note how weakercurrents can movesmaller particles ofsediment, whilestronger currentsare needed to erodelarger sediment.11Classifying SedimentSediment can also be classified according to its source.126

13Distribution of SedimentsThe sediment ofcontinental shelvesis called neriticsediment, andcontains mostlyterrigenousmaterial.Sediments of theslope, rise, anddeep-oceanfloors are pelagicsediments, andcontain a greaterproportion ofbiogenousmaterial.147

Shelf Sedimentation: Controlled byTides, Waves and CurrentsShoreline turbulence prevents small particlesfrom settling and transports them seawardwhere they are deposited in deeper water.Particle size decreases seaward for modernsediments.Past fluctuations of sea level have strandedcoarse sediment (relict sediment) across theshelf including most areas where only finesediments are deposited today.15Time Frames for Continental ShelfSedimentationFor a time frame up to 1000 years, waves,currents and tides control sedimentation.For a time frame up to 1,000,000 years, sea levellowered by glaciation controlled sedimentationand caused rivers to deposit their sediments atthe shelf edge and onto the upper continentalslope.For a time frame up to 100,000,000 years, platetectonics has determined the type of margin thatdeveloped and controlled sedimentation.168

Distribution4-2 of Modern ShelfSediments: Related to latitude andclimateCalcareous biogenic sediments dominatetropical shelves.River-supplied sands and muds dominatetemperate shelves.Glacial till and ice-rafted sedimentsdominate polar shelves.17Sediments of Deep-Ocean Basins Red Clays - very fine, slowly settling deposits Turbidites – deposits made by turbidity currents Oozes – deep-ocean sediment containing at least30% biogenous material Siliceous ooze Calcareous ooze Hydrogenous sediments - originate from chemicalreactions that occur in the existing sediment189

Biogenous OozesOoze is classified by the type of life form from which it isderived. Calcareous ooze is formed by organisms, such asforaminifera, which contain calcium carbonate in theirshells or skeletons. Siliceous ooze is formed by organisms that contain silica intheir shells. Diatoms are one type of organism whoseremains contribute to siliceous ooze. Hydrogenous sediments are usually the result of chemicalreactions. Hydrogenous sediments are often found in theform of nodules containing manganese and iron oxides.19Calcite (or Calcium Carbonate)Compensation Depth (CCD)CaCO3 dissolves in deeper water due tothe higher CO2 content in deep water Deepest sediments have little or no CaCO3 The CCD is deeper (less dissolution) in theAtlantic Ocean than in the Pacific. Why? 2010

Sedimentation in the Ocean Majorsedimentary processes in the deep seainclude: Bulk emplacement, Debris flows,Turbidity currents Major pelagic sediments in the ocean are redclay and biogenic oozes. Authigenic deposits are chemical andbiochemical precipitates that form on the seafloor and include ferromanganese nodules andphosphorite.21Distribution of Sediments in the DeepOcean: Related to Latitude, Distancefrom Landmasses, and the CCD Glacial marine sediments occur in thehigh latitudes. Pelagic clays occur far from land and inthe deepest water. Calcareous oozes occur above thecalcium carbonate composition depth. The rate of sedimentation depends onthe type of sediment in deep sea.2211

EvaporitesEvaporites are precipitates that form as waterevaporates or as the conditions in the waterchange Evaporites include many salts with economicimportance. Evaporites currently form in the Gulf ofCalifornia, the Red Sea, and the Persian Gulf.23Drying Up of the4-4 Mediterranean Sea TheMediterranean basin is located where platesare colliding as Africa moves northward relative toEurope. Anhydrite and stromatolites of Miocene ageindicate that the Mediterranean sea “dried” outbetween 5 and 25 million years ago. Two models have been suggested to account forthis emptying of the Mediterranean Sea of itswater. The “Uplift” Model The “Drying-Out” Model2412

Distribution of Sediments The sediment of continental shelves is called neritic sediment, and contains mostly terrigenous material. Sediments of the slope, rise, and deep-ocean floors are pelagic sediments

Related Documents:

May 02, 2018 · D. Program Evaluation ͟The organization has provided a description of the framework for how each program will be evaluated. The framework should include all the elements below: ͟The evaluation methods are cost-effective for the organization ͟Quantitative and qualitative data is being collected (at Basics tier, data collection must have begun)

Silat is a combative art of self-defense and survival rooted from Matay archipelago. It was traced at thé early of Langkasuka Kingdom (2nd century CE) till thé reign of Melaka (Malaysia) Sultanate era (13th century). Silat has now evolved to become part of social culture and tradition with thé appearance of a fine physical and spiritual .

On an exceptional basis, Member States may request UNESCO to provide thé candidates with access to thé platform so they can complète thé form by themselves. Thèse requests must be addressed to esd rize unesco. or by 15 A ril 2021 UNESCO will provide thé nomineewith accessto thé platform via their émail address.

̶The leading indicator of employee engagement is based on the quality of the relationship between employee and supervisor Empower your managers! ̶Help them understand the impact on the organization ̶Share important changes, plan options, tasks, and deadlines ̶Provide key messages and talking points ̶Prepare them to answer employee questions

Dr. Sunita Bharatwal** Dr. Pawan Garga*** Abstract Customer satisfaction is derived from thè functionalities and values, a product or Service can provide. The current study aims to segregate thè dimensions of ordine Service quality and gather insights on its impact on web shopping. The trends of purchases have

Chính Văn.- Còn đức Thế tôn thì tuệ giác cực kỳ trong sạch 8: hiện hành bất nhị 9, đạt đến vô tướng 10, đứng vào chỗ đứng của các đức Thế tôn 11, thể hiện tính bình đẳng của các Ngài, đến chỗ không còn chướng ngại 12, giáo pháp không thể khuynh đảo, tâm thức không bị cản trở, cái được

Le genou de Lucy. Odile Jacob. 1999. Coppens Y. Pré-textes. L’homme préhistorique en morceaux. Eds Odile Jacob. 2011. Costentin J., Delaveau P. Café, thé, chocolat, les bons effets sur le cerveau et pour le corps. Editions Odile Jacob. 2010. Crawford M., Marsh D. The driving force : food in human evolution and the future.

Automotive EMC testing with Keysight Jon Kinney RF/uW Applications Engineer 11/7/2018. Page How to evaluate EMI emissions with a spectrum/signal analyzer ? Keysight EMI Solutions 2 . Page Getting started –Basic terms Keysight EMI Solutions EMI, EMS, EMC 3 EMI EMS EMC Today, We focus here ! Page Why bother? EMC evaluation is along with your product NPI cycle 4 EMI Troubleshooting EMI Pre .