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Mediterranean's Messian Salinity Crisis: Geological Event of the Miocene Period

Explore the Messinian Salinity Crisis that led to the Mediterranean Sea drying up in the late Miocene era. Learn about geological implications, evaporites in Sicily, and the chalk-sulphurous formation.

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Mediterranean's Messian Salinity Crisis: Geological Event of the Miocene Period

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  1. ERASMUS PLUS 2015-2017 IIS LS PICCOLO CAPO D’ ORLANDO A4 INTERDISCIPLINARY CLASS SCIENCE CHEMISTRY

  2. The Messinian’s salinity crisis and the Sicilian evaporation When the Mediterranean dried up. • The work was prepared by Mrs. Nunziata Fonti • With the help of Mrs. M Pia Cocivera • Scientific high school Piccolo – Capo d’Orlando • January 2017

  3. Messian’s salinity crisis. The Messian’s salinity crisis or messinian event is the name that is given to that geological event during which the waters of the Mediterranean sea dried up almost completely in the last part of the Messinian period of the Miocene, due to the closure of the strait of Gibraltar.

  4. The Messinian:FramingChronogeological The Messinian geologic plane (from Messina, Italy); occurred between 7,24 and 5,33 millions, was theatre of reapeated evaporation of the Mediterranean, with the deposition and accumulation of a million km3 of evaporites, which is equivalent estimated at about 5% of salts dissolved in the oceans ( current average salinity: 35 for thousand)

  5. Mediterranean's situation in the late Miocene( six millions of years ago) www.digilands.it

  6. 5.96 millions of years ago: the strait of Gibraltar closure - the Mediterran becomes an expense of salt and earth - www.digilands.it 5.33 million of years ago: the strait of Gibraltar reopens

  7. 5.33 millions years ago: end of salinity The return of oceanic water was very fast in all the Mediterranean (2 years?), since it is observed an abrupt change in sediments, with deposits of clay immediately above evaporates.The setting velocity that were very high during the Messinian (several millimeters, year) befall abruptly a few cm/1000 years. The rapid return to the initial conditions also caused considerable erosion.

  8. When an isolated marine basin evaporates almost completely , they are deposited on the bottom of the reverse order of their solubility: firstly, the calcite and dolomite, then the plaster and dioxide, finally holite, sylvite and the carnalite. This way ,extended salt deposits are formed, with thicknesses of tens of meters.

  9. The chalk -sulphorousformation In Sicily, and in the Italian peninsula, there is the most beautiful existing evaporate sucession all over the world, known as the "chalky-sulphorous training". They are big chalk deposits, limestone solfiferi, rock salt and other more soluble salts (for example potassium salts) in less quantities intercalated clays and marls dating from the Messinian period (almost 5-6 millions of years ago).

  10. The chalk - sulphorousformation The sequence of deposition also reflects the saline solubility and it can be represented as follows:CaCO3(calcite)  CaSO4• 2H2O (chalk)  CaSO4(anhydride) NaCl (rock salt)  MgSO4•7H2O (epsomite)  KCl (sylvite)  MgCl2 •KCl•6H2O (carnallite)  MgCl2•6H2O (bischofite)  borates

  11. Evaporites in Sicily The evaporites in Sicily are concentrated in the south central area of the island, that is in the provinces of Caltanissetta, Enna and Agrigento. However, there are evaporite deposits also in the provinces of Palermo (Ciminna, Villafrati, Lercara) and Trapani (Entella).

  12. Chalk The Chalk is a salt: bi-hydrate calcium sulphate, CaSO4.2H2O - that is part of the evaporite sedimentary rocks because it owes its origin to the seawater evaporation. The chalk formation that rises in Sicily dates back to 5-6 millions of years ago. (Messinian)

  13. Regardless of age of the formation the chalk landescape in out crops, is characterized by the fact that almost always they are in an elevated position, compared to the sorrounding rock formations and therefore the chalky findings soar and they are clearly visible at the horizon. THE CHALK'S LANDESCAPE Ciminna greenhouses (reliefs originated during the Messinian salinity crisis)

  14. Rock salt Rock salt's mine of Petralia (PA) one of Europe’s richest deposits: an enormous lens of rock salt contained in the heart of a mountain that rises up to 1.100 meters above sea level, for an extension of 2 km² away and a thickness which reaches the value of 400 m, with a sodium content of up to 99,9 %. It appears in crystals, granular or fibrous aggregates, crusts and stalactites. Named also "quarry salt", "mines's salt“ or halite (salt's stone), the rock salt is used for the sodium chloride's production (NaCl), usually called salt. The crystalline salt has a cubic web.

  15. Sulfur Since that the sicilian sulfur's deposits date back to the Messinian, it's very probable that they are the indirect results of the salinity Crisis of the Mediterranean sea after the Strait of Gibaltar's closure. It is hypothesized that this mineral is the result of the action of certain bacteria that would be able to extract sulfur from waters containing sulphate (mainly chalks and anhydrides) or chemical process: chalk  calcite + sulfur The Sicily's sulfur was one of Sicily’s most important mineral resources, today no longer used. For a determined period it has represented also the biggets area of worldwide production.

  16. Chalk and Sulfur

  17. Rock salt: NaCl The blue color of crystalis due to the partialmodification of the crystal lattice thatis due to element’sinclusionssuchaspotassium.

  18. Realmonte’s Mine - At approximatelly 9 km from Agrigento and at 3 km from Port Empedocle the thickness saline lens of 40 m. With rock salt and Kainit’s layers – KCl ∙ Mg SO4 ∙ 3H2O – chloride of K and sulfate of Mg. Excavated at 150 meters below the surface and at 30 from the sea level it is one of the most important sources of salt extraction on the island and it can produce almost 500 thousand tons of salt a year. The galleries extend for more than 30 km.

  19. 75 meters from the surface, in the walls of the mine, there is a rose window formed from the intersection of rock salt with other salts. The result is a series of concentric circles of different colors, a real natural spiral with light and dark patches that date back to 5 million years ago

  20. In addition to for the production of rock salt kainite, the mine is best known for its interior treasure, namely the presence of the Cathedral of salt, a church carved by miners where every year on December 4 is celebrated Santa Barbara’s festival, their patron. The church is located at 100 m. below the surface and 30 m. below sea level.

  21. Wide 20 meters high and 8 with a length of about 100 meters, the salt cathedral could contain 800 seats. There are sacred sculptures, statues and furniture all carved into the rock, there is the table made from a large block of salt, there are also the frescoes including the holy family, the Christ on the cross and Santa Barbara. Outline the ambo hosts the cross and the Easter candle at the entrance instead of only two fonts carved blocks.

  22. 40 meters deep, there is a cave where water infiltration melt the mineral of time to solidify in the form of thin and long lines of petrified salt stalactites that sparkle like crystal, creating a very striking visual effect.

  23. The precipitation of a salt - Laboratory Experience - The precipitation of a salt may be: by evaporation of a solvent, for which the solution becomes saturated; the union of two different solutions that lead to the formation, by interaction of the ions present simultaneously in the solution obtained, a new salt, a little soluble.

  24. Double exchange reactions: the compounds exchange their "partners" and the two reactants can be achieved:    a) a compound insoluble (precipitate)    b) a stable molecule, which H2O    c) development of a gas + + AD+CB AB+CD

  25. KNO3 + PbI2 ↓ Potassium Nitrate + Lead Iodite The double-exchange reaction between two colorless soluztions form a precipitate of yellow color. Pb(NO3)2 + KI = Pb(NO3)2 + KI = Lead Nitrate + Potassium Iodite

  26. BaCrO4 ↓ + 2 KCl Baium Chromate ↓ + Chloride Potassium The double-exchange reaction between two soluztions form a precipitate of intense yellow color. K2CrO4 + BaCl2 Potassium Chromate + Barium Chloride La precipitazione del KrCrO4

  27. Formation of an insoluble substance (precipitate) 2AgNO3+K2CrO4Ag2CrO4+ 2KNO3 BaCl2+H2SO4BaSO4+ 2 HCl Na2S + CuCl2CuS+2 NaCl

  28. Examples.

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