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FROM THE MIDOCEAN RIDGES TO THE BLACK SMOKERS

FROM THE MIDOCEAN RIDGES TO THE BLACK SMOKERS. What is it a midocean ridge?. A midocean ridge it’s due to the divergence between two plates (e.g. The African plate and the South-American plate ). . The birth of the Atlantic Ocean (from Zullini ). The plates move away one from the other.

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FROM THE MIDOCEAN RIDGES TO THE BLACK SMOKERS

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  1. FROM THE MIDOCEAN RIDGES TO THE BLACK SMOKERS

  2. What is it a midocean ridge? A midocean ridge it’s due to the divergence between two plates (e.g. The African plate and the South-American plate ). The birth of the Atlantic Ocean (from Zullini) The plates move away one from the other.

  3. How long are the Oceanic spreading ridges? The Oceanic spreading ridges measure about 60.000 km in length. They occupy about 10% of the earth’s surface.

  4. The Mid-Atlantic Ridge The Mid-Atlantic Ridge goes from the Greeenland in the north (80° N latitude) to the end of South America in the south (55°S latitude).

  5. How born a mid-oceanridge Due to the rise of the molten mantle, the lithosphere is broken resulting in the formation of a narrow valley, called «rift» (as the «Great Rift Valley» in Africa). The rift is surrounded by normal faults (red lines in the picture). From the rift exits the lava. The Great Rift Valley in Africa (from Zullini). The blacktriangles indicate the activevulcanos.

  6. From the Rift Valley to the Ocean If the spreadingcontinuestherewill be the formation of a sea (e.g the Red Sea) and finally an Ocean (e.g. the Atlantic Ocean ). http://www.vialattea.net

  7. Whathappens in a midoceanridge Along the ridges the molten rock (the magma) coming from the asthenosphere is driven by convective motions breaking the oceanic crust and causing undersea volcanic eruptions. http://kidslink.bo.cnr.it http://try.iprase.tn.it

  8. Alvin and the «blacksmokers» Deep-sea hydrothermal vents occur along the midocean ridges. Several different vents have been discovered since the first site was found in 1977 near the Galapagos Islands by earth scientists in the small research submersible ALVIN. One reason that relatively few sites have been observed is that scientists have explored only a small portion of the 50,000 kilometers of midocean ridges Da http://www.divediscover.whoi.edu/

  9. The «blacksmokers» These black smokers are chimneylike structures made up of sulfur-bearing minerals or sulfides that come from beneath Earth's crust. They form when hot (roughly 350¡C), mineral-rich water flows out onto the ocean floor through the volcanic lava on a mid-ocean ridge volcano.

  10. The blacksmokers Deep-sea hydrothermal vents support extraordinary ecosystems deep beneath the surface of the oceans. These ecosystems are the only communities on Earth whose immediate energy source is not sunlight. Life on Earth, and even possibly on other planets, may have formed in environments similar to these. http://www.youtube.com/watch?v=AlHJqA8YkoI&feature=player_detailpagegulf of California 2003 blacksmoker Sopra, agglomerato di batteri tube worms

  11. The blacksmokers Above:Instead of photosynthesis, ventecosystems derive theirenergy from chemicals in a processcalled "chemosynthesis." Bothmethods involve an energy source (1), carbon dioxide (2), and water to produce sugars (3). Photosynthesisgives off oxygen gas as a byproduct, whilechemosynthesisproducessulfur (4). Image courtesy Woods HoleOceanographicInstitution.

  12. Life begannext to the blacksmokers? Unlike plants that rely on sunlight, bacteria living in and around the dark vents extract their energy from hydrogen sulfide (HS) and other molecules that billow out of the seafloor. Just like plants, the bacteria use their energy to build sugars out of carbon dioxide and water. Sugars then provide fuel and raw material for the rest of the microbe's activities. Astrobiologists are increasingly convinced that life on Earth itself might have started in the sulfurous cauldron around hydrothermal vents. Vent environments minimize oxygen and radiation, which can damage primitive molecules. Indeed, many of the primordial molecules needed to jump-start life could have formed in the subsurface from the interaction of rock and circulating hot water driven by hydrothermal systems.

  13. The chemistry of a blacksmoker Right: The chemistry of a "black smoker." After sea water seeps into the crust (1), oxygen and potassium (2) and then calcium, sulfate, and magnesium (3) are removed from the water. As the water begins to heat up (4), sodium, potassium, and calcium dissolve from the crust. Magma superheats the water, dissolving iron, zinc, copper, and sulfur (5). The water then rises back to the surface (6), where it mixes with the cold seawater, forming black metal-sulfide compounds (7). Image courtesy Woods Hole Oceanographic Institution.

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