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Metamorphic Rocks and Rock Cycle Shmulik Marco. 1.Igneous Rocks formed by solidification of molten rock (magma). Examples: basalt, granite. 2.Sedimentary.

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Presentation on theme: "Metamorphic Rocks and Rock Cycle Shmulik Marco. 1.Igneous Rocks formed by solidification of molten rock (magma). Examples: basalt, granite. 2.Sedimentary."— Presentation transcript:

1 Metamorphic Rocks and Rock Cycle Shmulik Marco

2 1.Igneous Rocks formed by solidification of molten rock (magma). Examples: basalt, granite. 2.Sedimentary Rocks formed as layers of sediments accumulate. Examples: sandstone, limestone. Three Basic Types of Rocks

3 3. Metamorphic Rocks ormed by transformation of preexisting rocks in the solid state under high pressures and temperatures Formed by transformation of preexisting rocks in the solid state under high pressures and temperatures Differential Pressure Lithostatic Pressure

4 Metamorphism: Processes of generating metamorphic rocks. Rocks undergo mineralogical and physical changes in solid state

5 Metamorphic Textures Foliation –set of flat or wavy parallel surfaces produced by deformation –define a preferred orientation, usually perpendicular to directed pressure and parallel to shear –often expressed in orientation of “platy” minerals such as micas

6 Schist – Preferred Orientation Foliation

7 Foliated Rock: Schist 5 cm 10 cm

8 Metamorphic Textures: Foliation and Cleavage Foliation –set of flat or wavy parallel surfaces produced by deformation –define a preferred orientation, usually perpendicular to directed pressure and parallel to shear –often expressed in orientation of “platy” minerals such as micas and chlorite

9 Granite – Equidimensional Crystals, No Preferred Orientation

10 Gneiss with Lineation

11 Gneiss – Preferred Orientation Lineation

12 Metamorphic Textures Lineation

13 Ductile Deformation: Folds

14 Quartzite No preferred orientation

15

16 Metamorphic Minerals Grow in rocks only during metamorphism (solid state!) Indicative of pressure and temperature Do not form from cooling magma

17 Contact Metamorphism Contact Metamorphism: The main metamorphic agent is heat.

18 Pressure & Temperature Regimes

19 Pressure –Increases with depth at about 1/3 kilobar per kilometer –Does not vary much with geographic position or plate- tectonic setting

20 Pressure & Temperature Regimes Temperature: Increases with depth at a rate that varies substantially with plate-tectonic setting 20ºC per kilometer in stable continental crust 40ºC per kilometer in orogenic belts 60ºC per kilometer in volcanic regions

21 Pressure & Temperature Regimes Deformation stress –Direction varies substantially with plate-tectonic setting –Magnitude limited by strength of rocks to be less than 1 kilobar

22 Metamorphic Grade 60º/km 40º/km 20º/km Geologists determine pressure and temperature from mineral assemblages –geothermometers –geobarometers

23 Types of Metamorphism Regional metamorphism –caused by large-scale lithospheric movements Contact metamorphism –caused by high temperatures near magmatic intrusions Deformation metamorphism –caused by faulting, tight folding, and shearing Hydrothermal metamorphism –caused by circulation of hot fluids Burial metamorphism –caused by subsidence and burial of sediments

24 PTt Path 1.Original rock forms: t 0 2.Burial, pressure and temperature increase, metamorphism, : t 1 - t 3 3.Exhumation: t 4 - t 5 P T t1t1 t2t2 t3t3 t0t0 t4t4 t5t5

25 Rock Cycle סלעים מגמתיים סלעים סדימנטריים סלעים מטמורפיים מטמורפוזה התכה מטמורפוזה התכה אירוזיה

26 Rock Cycle


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