Geol 1360 Ch 4

carbonates

2 most important carbonate minerals in marine sediment are calcite and aragonite- hydrogenous carbonate deposits can precipitate directly from seawater in tropical climates to form aragonite crystals or oolites.

calcium carbonate biogenous ooze

2 sources of this are foraminifers, and coccolithophores

prokaryotic

An organism whose cells do not have an enclosed nucleus, such as bacteria.

eukaryotic

Has a nucleus

carbonate deposits

Neritic biogenous deposit; simply limestone

upwelling

The movement of deep, cold, and nutrient-rich water to the surface, occurs near continental margins

silt

a particle size of .0003 to .002 inch . it is intermediate in size between sand and clay

pelagic sediment types within each major ocean

abyssal clay dominates in the pacific ocean while calcareous ooze dominates in the shallower atlantic and indian oceans

siliceous ooze

accumulation of siliceous tests of diatoms, radiolarians, and other silica-secreting organisms

weathering

agents such as water, temperature, extremes, chemical effects break rocks into smaller pieces

oolites

are small calcite spheres .08 inch or less in diameter that have layers like an onion and form in some shallow tropical waters where concentrations of calcium carbonate are high

metal sulfides

associated with hydrothermal vents and black smokers along mid ocean ridge- iron, nickel, copper, zinc, silver and other metals can be found on the ocean floor and uplifted onto continents

calcite compensation depth CCD

below the lysocline, calcum carbonate dissolves at an increasing rate with increasing depth until the CCD is reached- above CCD is not dissolved, Below CCD it is dissolved

what is a typical (ballpark) rate of deep sea sediment deposition?

biogenous ooze- .4 inch, abyssal clay- .04 inch, manganese nodule- .00004 inch per 1000 years

wentworth scale of grain size

boulders, cobbles, pebbles, granules, sand, silt, clay lithogenous sediment tends to become finer with increasing distance from shore

pteropod ooze & ostracod ooze

calcareous oozes named for the marine organisms whose shells are primary components of the sediment

2 most common chemical compounds in biogenous sediment

calcum carbonate and silica- silica is combined with water to form hydrated form of silica -opal

precipitate

change from the dissolved to the solid state-liquid to vapor

foraminifer

close relatives of radiolarians- no photosynthetic (no sun)

nannoplankton

coccolithophores are about 10x-100x smaller than most diatoms

abyssal clay

composed of at least 70% fine clay sized particles from continents- abundance of abyssal clay on abyssal plains is due to absence of other material that would dilute it

aragonite

composed of calcium carbonate but has a different crystalline structure that is less stable and transforms into calcite over time

coccolith ooze

conisists mostly of coccolithophores

foraminifer ooze

consists mostly of foraminifers-

silicoflagellate ooze

consists of mostly single celled silicoflagellates (protozoan)

pelagic

deep ocean-siliceous ooze, calcareous ooze

calcareous ooze

deposits comprised primarily of tests of foraminifers coccoliths and other calcareous secreting organisms

lysocline

depth in the ocean at which the pressure is high enough and the amount of carbon dioxide in seawater great enough to begin dissolving calcium carbonate

evaporites

form wherever there are high evaporation rates (dry climates) accompanied by restricted open ocean circulation- ex mediterranean sea thick deposits of evaporites on floor suggest in geologic past sea dried up completely ex- halite,calcium sulfate anhydrate, gypsum

calcareous ooze

found along segments of the mid ocean ridge in shallower areas of the ocean floor beneath warmer surface water

phosphorite

found in continental shelf

evaporites

found in shallow restricted basins where evaporation is high in low latitude regions

oolites

found in shallow shelf in low latitude regions

manganese nodules

from abyssal plain

lithogenous sediment types

from continents made of quartz-silicon and oxygen -form by erosion-from size of boulders to clay distributed in neritic (near shore) or pelagic (deep ocean)

metal sulfides

from hydrothermal vents at mid ocean ridges

Iron-nickel meteorites

from meteors found localized near meteor impact structures

iron-nickel spherules Tektites

from space dust- found in very small proportions mixed with all types of sediment and in all marine environments

Hydrogenous sediment

from the dissolved material in water-relatively small portion of the overall sediment in the ocean

biogenous sediment

from the remains of hard parts of once living organisms, -organisms that contribute to this are algae, and protozoans

planktonic

having characteristics of plankton-passively drifting or weakly swimming organisms that are not independent of currents.

siliceous ooze location

in cool water beneath cool surface water regions- and (upwelling)where deep ocean water comes to the surface and supplies nutrients that stimulate high rates of biological productivity- near continental margins

distribution of neritic and pelagic sediment

influenced by proximity to sources of lithogenous sediment, productivity of microscopic marine organism, the depth of the ocean floor and the distribution of various sea floor features

lithogenous sediment

is derived from preexisting rock material that originates on the continents or islands from erosion, volcanic eruptions or blown dust. also terrigenous sediment-largest amount is around trenches, constantly moved by high energy currents along shoreline and turbidity currents in deeper water

protozoans

large group of single celled eukaryotic usually microscopic organisms that are generally not photosynthetic

diatomaceous earth-(diatomite tripolite, kieselguhr)

lightweight white rock composed mainly of diatom test and clay

stromatolites

lobate structures consisting of fine layers of carbonate that form in specific warm shallow water environments - produced by cyanobacteria

sand

majority of lithogenous deposits composed of primarily quartz

rivers

many rivers of world today drop sediment in drowned river mouths rather than carry it onto the continental shelf (due to glacial melting and rising sea level)

turbidite deposits

material spreads out as deep sea fans, makes up the continental rise and gradually thins toward abyssal plains

hydrogenous sediment types

metal sulfides, manganese nodules, phosphates, carbonates, evaporites

coccolithophore

microscopic algae-photosynthetic(sun)-single celled

diatom

microscopic algae-they need strong sunlight and found only within upper sunlit surface waters of ocean-photosynthesize-planktonic (free floating)

biogenous sediment types

microscopic or macroscopic, algae -sun- eukaryotic-(nucleus) or protozoan(no sun- single celled -eukaryotic (nucleus

tests

microscopic organisms produce tiny shells(tests) that begin to sink after the organisms die and continually rain down in great numbers onto the ocean floor

radiolarian

microscopic single celled protozoans-planktonic (free floating)

cosmogenic sediment types

microscopic spherules, macroscopic meteor debris

characteristics of marine sediments-calcareous ooze

most calcareous ooze contain some siliceous material and vice versa

silica

most comes from microscopic algae-sun(diatoms) and protozoans-no sun(radiolarians)

neritic

near shore-carbonate deposits (limestone) and stromatolites

distribution of lithogenous sediment

neritic deposit(near shore), pelagic deposits (deep ocean), beach deposits, continental shelf deposits, turbidite deposits, glacial deposits, ice rafting, abyssal clay

phosphate

occur abundantly as coatings on rocks and as nodules on the continental shelf and on banks at depths shallower than 3300 feet

areas of thick sediment accumulation

occur on the continental shelves and rises especially near the mouths of major rivers

globigerina ooze

one of the most common types of foraminifer ooze named for a foraminifer that is especially widespread in the atlantic and south pacific oceans

calcite accumulation

only near the tops of the tall peaks that rise off the sea floor and extend above the CCD but dissolves at deeper depths associated with the base of the peaks

sand

particle size of .002 to .08 inch. It pertains to particles that lie between silt and granules on the wentworth scale of grain size

algae

primarily aquatic, eukaryotic (has a nucleus), photosynthetic organisms like giant kelp

fecal pellets

rapidly transports biogenous particles to the deep ocean floor and cause the composition of sea floor deposits to match the organisms living in surface waters immediately above them.

continental shelf deposits

relict sediments,cover the continental shelf deposited 3000-7000 years ago and not covered by sediments discharged by rivers today- cover 70% of worlds continental shelves

ice rafting

rock particles trapped in glacial ice are carried out to sea by icebergs that break away from coastal glaciers

manganese nodules

rounded, hard lumps of manganese, iron, and other metals from 2 inches- inches-they reveal a layered structure formed by precipitation around a central nucleation object- piece of lithogenous sediment , coral, volcanic rock, fish bone ,sharks tooth

radiolarian ooze

sediment made up of more than 30% skeletal remains of radiolarians

opal

silica is combined with water to form hydrated combination of silica

microscopic spherules

small globular masses composed of silicate rock material (tektites) or iron and nickel, space dust

ooze

tests can accumulate on the deep ocean floor and form these deposits- consistency of toothpaste mixed about half and half with water-must contain at least 30% biogenous test - 70% lithogenous clay

use Hjulstroms diagram to explain erosion

the greater the weight and velocity to transport the more likely it is that the sediment would be eroded.

characteristics of marine sediments-hydrogenous sediment

there are many types of hydrogenous sediment

characteristics of marine sediments- lithogenous clay

these particles are incorporated into every sediment type, contains small % of biogenous particles, biogenous ooze includes up to 70% fine grained lithogenous clays

characteristics of marine sediments -cosmogenous sediment

tiny amounts of cosmogenous sediment are mixed in with all other sediment types

lithify

transform into stone

macroscopic meteor debris

very rare, show up where meteors hit earth- silicate rock material(chondrites) of iron and nickel(irons)

lithogenous sediment cycle steps

weathering, erosion,transportation, deposition,lithification, uplift--