Earth Science Class - Magmatism PDF

WELCOME TO EARTH SCIENCE CLASS WHAT I NEED TO KNOW  For week 3 module, you are expected to:  identify the composition of magma;  2. discuss how magma is formed; and  3. explain what happens after magma is formed Do you think magma rises or stays in place? ...

WELCOME TO EARTH SCIENCE CLASS WHAT I NEED TO KNOW  For week 3 module, you are expected to:  identify the composition of magma;  2. discuss how magma is formed; and  3. explain what happens after magma is formed Do you think magma rises or stays in place?  MAGMA  composed of semi-liquid hot molten rocks located beneath the Earth, specifically in the melted mantle rock and oceanic plate.  MAGMA and LAVA  Magma and Lava are both molten rocks. Magma is found in the magma chamber of the volcano while lava is found on the surface of the earth once the volcano erupts.  MAGMATISM  The formation and movement of magma under the earth's crust.  WHERE DOES THE FORMATION OF MAGMA TAKES PLACE? ASTHENOSPHERE a hot, mobile layer of partially molten rock lying within the earth's upper mantle. It is where the formation and movement of magma occur.  There are also many different gases dissolved in magma. Water vapor, carbon dioxide and hydrogen sulfide are common. There can even be gaseous forms of hydrochloric or sulfuric acid. Sometimes gas bubbles will form in the melt.  HOW IS MAGMA FORMED? GEOTHERMAL GRADIENT IS THE RATE OF INCREASING TEMPERATURE WITH RESPECT TO INCREASING DEPTH IN THE EARTH'S INTERIOR  PARTIAL MELTING  Rocks are made up of different minerals that have different melting points. When hot rocks begin to melt deep down beneath the surface, some of the minerals start to melt but others stay solid.  WHY ROCKS MELT - THE MAGMA THAT IS PRODUCED BY PARTIAL MELTING IS LESS DENSE THAN THE SURROUNDING ROCK - MAGMA FROM PARTIAL MELTING OF MANTLE ROCKS RISES UPWARD THROUGH THE MANTLE, AND MAY POOL AT THE BASE OF THE CRUST, OR RISE THROUGH THE CRUST. - MOVING MAGMA CARRIES HEAT WITH IT, AND SOME OF THAT HEAT IS TRANSFERRED TO SURROUNDING ROCKS - IF THE MELTING TEMPERATURE OF A ROCK IS LESS THAN THE TEMPERATURE OF THE MAGMA, THE ROCK WILL BEGIN TO MELT  DECOMPRESSION MELTING - INVOLVES THE UPWARD MOVEMENT OF EARTH'S MOSTLY SOLID MANTLE. - THIS HOT MATERIAL RISES TO AN AREA OF LOWER PRESSURE THROUGH THE PROCESS OF CONVECTION - AREAS OF LOWER PRESSURE ALWAYS HAVE A LOWER MELTING POINT THAN AREAS OF HIGH PRESSURE. - THIS REDUCTION IN OVERLYING PRESSURE, OR DECOMPRESSION, ENABLES THE MANTLE ROCK TO MELT AND FORM MAGMA. - DECOMPRESSION MELTING OFTEN OCCURS AT DIVERGENT BOUNDARIES, WHERE TECTONIC PLATES SEPARATE. - THE RIFTING MOVEMENT CAUSES THE BUOYANT MAGMA BELOW TO RISE AND FILL THE SPACE OF LOWER PRESSURE. THE ROCK THEN COOLS INTO NEW CRUST. - DECOMPRESSION MELTING ALSO OCCURS AT MANTLE PLUMES, COLUMNS OF HOT ROCK THAT RISE FROM EARTH’S HIGH-PRESSURE CORE TO ITS LOWER-PRESSURE CRUST - WHEN LOCATED BENEATH THE OCEAN, THESE PLUMES, ALSO KNOWN AS HOT SPOTS, PUSH MAGMA ONTO THE SEAFLOOR. THESE VOLCANIC MOUNDS CAN GROW INTO VOLCANIC ISLANDS OVER MILLIONS OF YEARS OF  WHEN PRESSURE DROPS, ROCKS WILL UNDERGO PARTIAL MELTING. IF THE PRESSURE KEEPS DECREASING, THE ROCK WILLCOMPLETELY TRANSFORM INTO MAGMA FLUX MELTING OCCURS WHEN WATER OR CARBON DIOXIDE ARE ADDED TO ROCK. THESE COMPOUNDS CAUSE THE ROCK TO MELT AT LOWER TEMPERATURES.  FLUX MELTING - FLUX MELTING ALSO OCCURS AROUND SUBDUCTION ZONES - IN THIS CASE, WATER OVERLYING THE SUBDUCTING SEAFLOOR WOULD LOWER THE MELTING TEMPERATURE OF THE MANTLE, GENERATING MAGMA THAT RISES TO THE SURFACE. Viscosity is defined as the ability of a substance to resist flow Magmas that have a high silica content will therefore exhibit greater degrees of polymerization, and have higher viscosities, than those with low-silica contents. The amount of dissolved gases in the magma can also affect it's viscosity Viscosity: a measure of a fluid’s resistance to flow. Magmas with low viscosity flow more easily than those with high viscosity. Temperature, silica content and volatile content control the viscosity of Different factors that affect magma’s viscosity. What happens to magma after it is formed?  VOLCANISM process when magma tries to escape from the source through openings such as volcanoes or existing cracks on the ground magma comes out with extreme heat and pressure and may cause destructive explosions  Magma escaped in two forms: ejected out to the surface through volcanoes( EXTRUSION)  solidifies within the shallower levels(INTRUSION)  Describe how magma is formed Magma is formed when hot rocks in the Earth partially melt which occurs when: - the pressure decreases - when volatiles are added to hot rocks and - increase in temperature If you are a resident of the island, will you go back in your houses? Why or why not?