Presentation is loading. Please wait.

Presentation is loading. Please wait.

Rock Identification Rock Lab. Identification of all three rock groups is based on TEXTURE and COMPOSITION Identification of all three rock groups is based.

Similar presentations


Presentation on theme: "Rock Identification Rock Lab. Identification of all three rock groups is based on TEXTURE and COMPOSITION Identification of all three rock groups is based."— Presentation transcript:

1 Rock Identification Rock Lab

2 Identification of all three rock groups is based on TEXTURE and COMPOSITION Identification of all three rock groups is based on TEXTURE and COMPOSITION the appearance of the rock rock what the rock is made out of – type of minerals what the rock is made out of – type of minerals Love it, Learn it, Live it, be one with it!

3 Igneous Rock Classification Lets form an igneous rock Two major types of igneous rocks Lets form an igneous rock Two major types of igneous rocks Intrusive – magma solidifies below the Earths surface magma cools very slow crystals form interlocking mosaic textures very coarse-grained visible minerals referred to as Plutonic rocks Intrusive – magma solidifies below the Earths surface magma cools very slow crystals form interlocking mosaic textures very coarse-grained visible minerals referred to as Plutonic rocks Extrusive – magma solidifies above the Earths surface magma cools very fast minerals can not be seen with un-aided eye very fine-grained texture (no visible minerals referred to as Volcanic rocks Extrusive – magma solidifies above the Earths surface magma cools very fast minerals can not be seen with un-aided eye very fine-grained texture (no visible minerals referred to as Volcanic rocks

4 Igneous Rock Classification Identification of igneous rocks is based on two main characteristics Texture – the appearance of the rock due to the rate of magma cooling Composition – the type of minerals found in the rock (mineral composition) Igneous Rock Classification Identification of igneous rocks is based on two main characteristics Texture – the appearance of the rock due to the rate of magma cooling Composition – the type of minerals found in the rock (mineral composition) Textures of Igneous Rocks Intrusive rocks (Textural terms) phaneritic texture – crystals are visible and form a mosaic of interlocking mineral aggregates (less than 1 cm) Textures of Igneous Rocks Intrusive rocks (Textural terms) phaneritic texture – crystals are visible and form a mosaic of interlocking mineral aggregates (less than 1 cm) Interlocking crystal grains phaneritic texture Interlocking crystal grains phaneritic texture

5 Extrusive Igneous Rocks (textural terms) aphanitic texture – crystals are too small to see See, you really can not see any mineral crystals magma cooled extremely fast (quenched) not enough time for atoms to combine (amorphous solid)- lacks a crystalline structure magma cooled extremely fast (quenched) not enough time for atoms to combine (amorphous solid)- lacks a crystalline structure glassy texture

6 Igneous Rock Classification Lab Vesicular texture- sponge like appearance, texture contains numerous cavities or holes Vesicles – gas bubbles cavities Pyroclastic texture – textures created by rapidly cooling lava that is hurled through the air picking up fragments (tuffaceous texture) Pyroclastic texture – textures created by rapidly cooling lava that is hurled through the air picking up fragments (tuffaceous texture) rock fragments – pieces of rock incorporated into the rock (tuffaceous) rock fragments – pieces of rock incorporated into the rock (tuffaceous)

7 Igneous Rock Classification Lab Igneous Rock Composition mineral composition = mineral assemblages= chemistry The mineral is either ferromagnesian (dark colored) or felsic (light colored ferromagnesian (mafic) minerals rich in Fe, Mg – creates a dark colored rocks Igneous Rock Composition mineral composition = mineral assemblages= chemistry The mineral is either ferromagnesian (dark colored) or felsic (light colored ferromagnesian (mafic) minerals rich in Fe, Mg – creates a dark colored rocks Pyroxene (Augite) Amphibole (hornblende) Mica - Biotite

8 Igneous Rock Classification Lab Igneous Rock Composition Mineral composition = Mineral assemblages = Chemistry The mineral is either ferromagnesian (dark colored) or felsic (light colored) Felsic – mineral composition is light colored minerals Igneous Rock Composition Mineral composition = Mineral assemblages = Chemistry The mineral is either ferromagnesian (dark colored) or felsic (light colored) Felsic – mineral composition is light colored minerals Ca-plagioclase K-feldspar (orthoclase) Mica- muscovite Quartz

9 Origin Texture Intrusive Phane- ritic Very coarse crystal grains, usually all grains are approximately the same size w/ respect to each other. Grains> one inch A mosaic of coarse-grains that are easily visible to the unaided eye – grains greater than 1 mm Granite Grano- diorite Diorite Gabbro Peridotite Granite Pegmatite Mafic Pegmatite Rhyolite Dacite Andesite Basalt X Extrusive Fine to very fine grains, usually to small to be distinguished with the unaided eye or even with a hand lens Aphan- itic Glassy Por- ous Frag- mental Obsidian PumiceScoria Rhyolitic Tuff Basaltic Tuff 80% 40% 20% Glassy – non-crystalline, non-granular Color varies between black and brown Highly vesicular, finely crystalline to glassy Pumice (light), Scoria (dark) Composed of fragments of all sizes Produced in volcanic environments, Ash Partially re-fused or cemented Very Coarse Rock Descriptions Igneous Rock Classification FelsicMafic

10 Sedimentary Rock Identification Lab Sandstone Arches

11 How is a sedimentary Rock formed??? Pre-existingRockPre-existingRock ErosionErosion Water, Wind, Ice Ice Breaks down Pre-existing rock Breaks down Pre-existing rock SedimentSediment TransportedTransported LakesLakes RiversRivers DepositedDeposited CompactedCementedCompactedCemented LithifiedLithifiedSedimentaryRockSedimentaryRock Why is the earths surface 75% sedimentary rocks?????????

12 Three major categories of Sedimentary Rocks Clastic Sedimentary rocks Chemical Sedimentary rocks Bio-chemical (bio-clastic) Sedimentary rocks Three major categories of Sedimentary Rocks Clastic Sedimentary rocks Chemical Sedimentary rocks Bio-chemical (bio-clastic) Sedimentary rocks

13 Clastic (inorganic-detrital) rocks are composed of particles or grains. Rock name is dependent on grain size. Decreasing grain size 2+ mm 2 mm 1/16 mm 1/256 mm

14 Chemical Rocks – inorganic, non-clastic rocks that are commonly the result of evaporation and precipitation Chemical rocks contain no fossils, or biological material but may react with HCl Chemical Rocks – inorganic, non-clastic rocks that are commonly the result of evaporation and precipitation Chemical rocks contain no fossils, or biological material but may react with HCl The Great Salt Lake, Utah halite (salt) crystals The Great Salt Lake, Utah halite (salt) crystals Calcium Carbonate (CaCO 3 ) chemical rocks (evaporation / precipitation processes) Calcium Carbonate (CaCO 3 ) chemical rocks (evaporation / precipitation processes) Chemically precipitated SiO 2

15 Bio-chemical (bio-clastic, biogenic) rocks – result from animal and plant secretions. The term clastic indicates that these rocks contain fossils or parts of plants shells, compacted plat material Bio-chemical (bio-clastic, biogenic) rocks – result from animal and plant secretions. The term clastic indicates that these rocks contain fossils or parts of plants shells, compacted plat material Animal parts Cemented shell fragments Lithified plant material

16 Classification Procedure Step 1: Determine if the rock is clastic or non-clastic Step 2: If the rock is clastic, determine the grain size and diagnostic properties. Make the ID. Step 2: If the rock is clastic, determine the grain size and diagnostic properties. Make the ID. Step 3: If the rock is not clastic, determine if the rock is either chemical or bioclastic chemical – will not contain particles such as grains and organic material. Test rock to observe fizzing (carbonates) Match diagnostic properties on chart for ID bio-clastic- rock will be composed of particles that are organic- animal parts, plant secretions. Test rock to observe fizzing (carbonate) Match diagnostic properties on chart for ID Step 3: If the rock is not clastic, determine if the rock is either chemical or bioclastic chemical – will not contain particles such as grains and organic material. Test rock to observe fizzing (carbonates) Match diagnostic properties on chart for ID bio-clastic- rock will be composed of particles that are organic- animal parts, plant secretions. Test rock to observe fizzing (carbonate) Match diagnostic properties on chart for ID

17 Metamorphic Rocks Meta (to change) morphic (form) = to change form Metamorphism– to change a rocks compositional and textural characteristics by subjecting the rock to various pressure/temperature relationships Rocks undergo a solid-state-transformation Metamorphism– to change a rocks compositional and textural characteristics by subjecting the rock to various pressure/temperature relationships Rocks undergo a solid-state-transformation The parent rock: represents the pre-existing rock metamorphism Example: Shale (parent) Schist Limestone (parent) Marble The parent rock: represents the pre-existing rock metamorphism Example: Shale (parent) Schist Limestone (parent) Marble

18 Identification of Metamorphic Rocks Identified by using the rocks Texture and Composition Compositional characteristics – types of mineral present common minerals: quartz, feldspar, muscovite special minerals: talc, garnet, chlorite related to P/T relationships Compositional characteristics – types of mineral present common minerals: quartz, feldspar, muscovite special minerals: talc, garnet, chlorite related to P/T relationships Textural characteristics – minerals are oriented in various degrees of parallelism platy sub-parallel parallel Textural characteristics – minerals are oriented in various degrees of parallelism platy sub-parallel parallel Grain size distribution – fine-grain to coarse-grain reflects P/T relationships fine-grain coarse-grain Low P/T High P/T Grain size distribution – fine-grain to coarse-grain reflects P/T relationships fine-grain coarse-grain Low P/T High P/T FOLIATED

19 Gneissic Schistose Slaty Coarse-grained High P/T Fine-grained Low P/T Alternating light and dark mineral bands Alternating light and dark mineral bands Parallel to sub-parallel Mineral alignment Parallel to sub-parallel Mineral alignment compressed layering - platy compressed layering - platy

20 Textural characteristics Non-foliated texture – minerals are not visible and there orientation does not exist Rock is composed of single type chemistry. Non-foliated texture – minerals are not visible and there orientation does not exist Rock is composed of single type chemistry. NON-FOLIATED Example: rocks composed of CaCO 3 rocks composed of SiO 2 Example: rocks composed of CaCO 3 rocks composed of SiO 2

21 Shows NO foliation Composed of ONE COMPOSITION Shows NO foliation Composed of ONE COMPOSITION Quartz SiO 2 Quartz SiO 2 Calcite CaCO 3 Calcite CaCO 3 Plant Material C -carbon Plant Material C -carbon How can one Tell the Difference ? How can one Tell the Difference ? Fussed glass Scratches glass Hard H = 7 Fussed glass Scratches glass Hard H = 7 Sometimes xln Fizzes in HCl Soft H = 3 Sometimes xln Fizzes in HCl Soft H = 3

22 Classification Procedure Step 1: Determine if the rock is foliated or non-foliated does the rock contain parallelism or grains does the rock consist of a single chemistry with no visible grains? Step 1: Determine if the rock is foliated or non-foliated does the rock contain parallelism or grains does the rock consist of a single chemistry with no visible grains? Step 2: If the rock is foliated examine the degree of parallelism examine the grain-size distribution refer to charts for ID Step 2: If the rock is foliated examine the degree of parallelism examine the grain-size distribution refer to charts for ID Step 3: If the rock is non-foliated determine the composition of the rock determine the special characteristics Refer to charts for ID Step 3: If the rock is non-foliated determine the composition of the rock determine the special characteristics Refer to charts for ID


Download ppt "Rock Identification Rock Lab. Identification of all three rock groups is based on TEXTURE and COMPOSITION Identification of all three rock groups is based."

Similar presentations


Ads by Google