*SOLAR SYSTEM, EARTH FORMATION
109 Y (Billion Years)
-Optical and Radio Telescopes
108-106 Y (100 Million-Million Years)
-Ocean Sediment Cores
102-105 Y (100 - 100,000 Years)
-Ice cores, annual snow layers
-Trapped gas (air)
-Marine corals (growth bands)
-Sediment cores (Up to 200 million years)
-Written history (5000 Years)
1. Life formed ~ 3.1 billion years ago
2. Photosynthesis began ~ 3 billion years ago
3. Oxygen increases through time:
2 Billion years ago: 1% of todayAbout this time, RED rocks appear in the geologic record. This occurred through oxidation of iron from Fe (II) to Fe (III).
700 Million years ago: 10% of today
4. An OZONE (O3) Layer was produced in the upper atmosphere by the interaction of O2 with ultraviolet (UV) light. This shields the earth from Ultraviolet (UV) radiation. This allowed life to proliferate on land.350 Million Years ago: 100 % of today
1) O2 -------------> 2O
diatomic -------------> atomic
2) O +
O2 ----------> O3
atomic diatomic------> ozone
O3 -------------> O2 + O
Ozone is mostly in a band 10 to 25 miles above sea level. This protective layer is being damaged by the release of chloroflurocarbons, and certain nitrogen compounds (NO, NO2).
Climate Indicators in the Ice
1. The Oxygen Isotope Record - indicates amount of glacial ice
There are two isotopes of oxygen......O16 and O18 --- H2O16 and H2O18
*When ice forms, the O16 stays
in the ice, the O18 stays in the water.
*So during glacials, there is more O18 in the ocean, and more O16 in the
2. The CO2 Record
*The ice record the atmospheric CO2 content.
3. The Dust Record
*The ice records the dust in the air.
Sedimentary Sources and Processes: Where do the sediments come from?
Primary Source: Weathering - water, wind and ice erodes continental rocks, soils
neritic sediments -pelagic sediments -continental shelves, current or wave deposited, coarse grained, accumulate very rapidly >10 cm/1000 yr.
deep sea, material that is deposited from suspension fine grained, accumulate slowly 0.1 to 1 cm /1000 yr.
2. Hydrogenous (Chemical precipitates)Glacial marine sediments - high latitudes - ice rafted sediments
Rivers - carry terrigeneous. sediments to the cont. margin
Eolian - winds transport fine dust particles 1000's of kilometers
3. Cosmogenic and Volcanogenic Sediments (minor)- minerals precipitated directly from seawater -Sources of dissolved ions for precipitates include rock, seawater, sediment,evaporites - form in isolated seas in areas of high evaporationsalt (NaCl)-hydrothermal systems- sulfide deposits rich in zinc, iron, copper, and silver, along the mid-ocean ridgesPrecipitate from hot hydrothermal solutionsmanganese nodules
Cosmogenic - tektites - extraterrestrial origin -enter at the top of the atmosphere as dust and meteorites4. Biogenic - comprised of the fossil shells of microscopic organisms
Volcanic - ash - glassy - large and small fragments (pumice) -explosive volcanoes - deposit distinct ash layers over large areas of the world
Shell Construction -Organisms extract ions out of the seawater, Ca, HCO3, Si, to secrete organic tissue and skeletons (or shells)3 Categories of Biogenic Sedimentscarbonate - CaCO3 (calcite)siliceous - SiO2 - silicaorganic matter
1. Phytoplankton - unicellular algae (photosynthetic)-suspended organisms carried from place to place by currentsmost are microscopic almost too small to be seen by the naked eye
produce most of the ocean biomass - base of the marine food chain (grasses of the sea)2 groups:COCCOLITHS - carbonate plates (shields). common in warm watersDIATOMS - siliceous - silica shell, common in cold waters , upwelling waters
Most abundant zooplankton are the smallest: single cell organisms:2 groups:FORAMINIFERA - carbonate shellRADIOLARIA - siliceous shell
Sediments are generally a mixture of the above sediments (biogenic, terrigeneous)Distance from land -
Several factors control the relative % of each component
Deep ocean regions - oozes/claysNearshore - continental margindominated by terrigeneous sedimentsaccumulate more rapidly, thickest (10-100 cm/kyrs)
Ocean Ecology - Productivity (nutrients) - where the organisms growbiogenic rich sedimentsrelatively thin/slow accumulation (1-5 cm/kyrs)
nutrient distribution - high nutrient content- favors silica shelled organismsClimate -
Warm waters (low to mid-latitudes) - mostly calcareous microfossils
California - Santa Barbara, Santa Monica
Elsewhere - Gulf of Mexico, Persian Gulf, North Sea, and north coast of Australia, north slope of Alaska.