Dr. Salve P. N. M.A.,SET, Ph.D . Maharaja Jivajiro Shinde Mahavidyalya Shrigonda

1. Metamorphism Rock Dr. Salve P. N. • M.A.,SET, Ph.D. Maharaja JivajiroShindeMahavidyalyaShrigonda • Dist : Ahmednagar

2. Types of Metamorphism Regional Metamorphism: Large-scale deformation associated with T and P

3. 3 Types of Metamorphism Contact Metamorphism: The main metamorphic agent is heat.

4. Types of Metamorphism Mylonite from shear zone in Appalachians Dynamic metamorphism: Rock deformation associated with fault zones

5. Progression of metamorphism Start with a shale and then hit it with pressure and heat. Slate Phyllite Schist

6. You end up with something that is really Gneiss!

7. A foliation is any planar fabric in a metamorphic rock. In this case, the foliation is defined by aligned sheets of muscovite sandwiched between quartz grains. This slide is indicative of a phyllite. The foliation in this rock is a crenulation cleavage, and is developed after the horizonal foliation. This slide is indicative of a schist.

8. Index minerals for Regional Metamorphism In regional metamorphic terranes, the temperature and pressure regime is indicated by the distribution of metamorphic minerals across a large area. Low metamorphic grade (low T and P; <200oC): Slate and phyllite: chlorite, muscovite, biotite Intermediate metamorphic grade Schist: garnet, staurolite, kyanite High metamorphic grade - 800 degrees C (verging on melting) Gneiss: kyanite, sillimanite Highest metamorphic grade: Partial melting Migmatite: rock partially melts, but no mass loss. Hence the mineralogy tells us the metamorphic grade of the rock.

10. Sedimentary Rocks Lithification Sediments Deposition Transport Erosion Weathering

11. Weathering The sediments that make up sedimentary rocks are produced by: Mechanical & Chemical Weathering

12. Mechanical Weathering

13. Chemical Weathering

14. MineralStability

15. Products of Weathering • Lithic (Rock) Fragments(granite, basalt, schist, etc.) • Dissolved Ions(Calcium, Potassium, Sodium, etc.) • Rust Minerals(Hematite, Goertite, etc.) • Clay Minerals(Bentonite, Montmorillonite, etc.) • Residual Minerals(Quartz, Orthoclase, Muscovite, etc.)

16. Erosion & Transport Water Wind Ice Gravity

17. Deposition

18. Lithification Sediment Rock

19. Cementation • Typical Cement: • Calcite • Quartz

20. Sedimentary Rocks Identification Note: Use the same terms to describe sediments & sedimentary rocks. Only difference is lithification!

21. CompositionWhat minerals make up the rock? TextureWhat is the shape, size and orientation of the mineral grains that make up the rock?Major Difference:Crystalline vs. Clastic Rock Identification is based on:

22. Types of Sedimentary Rocks Detrital Rocks Chemical Rocks vs.

23. Difference: TextureDetrital (Clastic Texture)vs.Chemical (Crystalline Texture)

24. Detrital Rock Composition • Detrital Rocks • Lithic Fragments • Quartz • Clay Minerals • Fossil Fragments • Rust Minerals • Orthoclase • Muscovite / Biotite

25. Clastic Texture Grain Size Grain Sorting Grain Rounding Sediment Maturity Detrital Rock Texture

26. Grain Size • Gravel2mm • Sand1/16 mm • Mud - Silt1/256 mm • Mud - Clay

27. Detrital Rock Names(Based Primarily on Grain Size) Gravel Sized: Conglomerate Sand Sized: Sandstone Mud Sized: Mudstone Siltstone Shale

28. Sorting

29. Grain Roundness

30. Gravel Sized Detrital Rocks(Subdivided Based on Grain Roundness) Conglomerate Breccia

31. Maturity • Immature • Poorly Sorted • Angular grains • Mixed Compositionincluding clay • Mature • Well Sorted • Well Rounded • All Quartz

32. Sandstones(Subdivided based on maturity) Quartz Sandstone Arkose (Sandstone) Lithic Sandstone Greywacke

33. Sandstones Under a Scope

34. Detrital Sedimentary Rock ID

35. Crystalline Texture Coarse Fine Chemical Rock Texture

36. Chemical Sedimentary Rocks(Names based primarily on composition) • Composition • Calcite • Quartz (silica) • Halite • Gypsum • “Carbon” / Plant Remains • Basic Rock Name • Limestone • Chert • Rock Salt • Rock Gypsum • Peat or Coal

37. Chemical Rocks(Names based mainly on composition) Limestones Crystalline Limestone Fossiliferous Limestone Chalk

38. Chemical Rocks (cont.) Evaportites Chert Rock Salt Rock Gypsum Coal

39. Chemical Sedimentary Rock ID

40. Sedimentary Rocks on Earth

41. Transportation of sediments and formation of sedimentary rocks by mode of river water- deposition on the continent and on the ocean floor. Fluvial deposits Marine deposits

43. SEDIMENTARY ROCKS:are the secondary rocks which are formed from the loose fragments or detrital or clastic sediments produced by weathering of older rocks. • Almost 90% of earth crust is made up of igneous rocks • 75% of land surface on the earth is covered by thin veneer of sediments or sedimentary rocks. • These sediments are transported and deposited by river water, wind or by movement of glacial ice. Transportation is either in suspension or in solution. • When settle down on the beds of ocean, river and lakes undergo compaction/cementation for millions of years to formSEDIMENTARY ROCKS

44. IMPORTANCE OF SEDIMENTARY ROCK “Present is the key to the past” • Helps in knowing depositional environment viz. marine (ocean deposits), fluvial (river deposits), aeolian (wind deposits), glacial, estuarine, Lacustrine (lake deposits) etc. • Helps in knowing the provenance (i.e. source area of the sediments); change in climatic conditions i.e. in knowing and understanding old climate=paleoclimate.

45. TYPES OF SEDIMENTARY ROCKS Clastic rocks Chemical & Organic rocks • Sandstones • Conglomerates • Breccia • Shale/mudstones Carbonate rocks Organic rocks Form due to decomposition of organic remains under temperature and pressure eg. Coal/Lignite etc. Form basically from CaCO3 – both by chemical leaching and by organic source (biochemical) eg. Limestone; dolomite Evaporitic rocks These rocks are formed due to evaporation of saline water (sea water) eg. Gypsum, Halit (rock salt)

46. CLASTIC ROCKS • formed from broken rock fragments weathered and eroded by river, glacier, wind and sea waves. These clastic sediments are found deposited on floodplains, beaches, in desert and on the sea floors. solidify Clastic rocks • Clastic rocks are classified on the basis of the grain size: conglomerate, sandstone, shale etc.

47. GRAIN SIZE Sand 2- 0.062 mm Silt 0.062-0.004 mm Clay <0.004 mm Gravel >256-2 mm Boulder: >256mm Cobble: 64-256 mm Pebble: 4-64 mm Granule: 2-4mm Fine gravel

48. Clastic rocks mainly comprise broken fragment of older rock – they are also know as Terrigenous rocks

49. Matrix: is the finer grains or material that surrounds the larger clasts. It consist of either clay, silt and sand. • Cement: dissolved substance that bounds the sediments. • Calcareous • siliceous Fine-gravel/ Granule (size <4mm) Any rock fragment (size is > 4 mm=Pebble)

50. Degree of roundness helps in knowing the distance of transportation • Angular clasts- short distance transport from the source • Rounded clasts- long distance transport