Sedimentary Rock II Sedimentary Rocks II Sedimentary Rock Types Characteristics of clastic rocks 5. Color: • presence of key components (can be minor by volume) Sedimentary Rock Types Characteristics of clastic rocks 5. Color: • BLACK: organic carbon, iron sulfide Sedimentary Rock Types Characteristics of clastic rocks 5. Color: • BLACK: abundant dead organisms and stagnant water (not enough oxygen for decomposition) Sedimentary Rock Types Characteristics of clastic rocks 5. Color: • BLACK: still water: swamp, lake, deep marine Sedimentary Rock Types Characteristics of clastic rocks 5. Color: Iron Oxide high O2 (continental) Red or Brown: http://www.visitortips.com/images/gallery/destinations/usa/colorado/denver/fullsize/denver12.jpg Sedimentary Rock Types Characteristics of clastic rocks 6. Lithification: • transformation of loose sediment into a rock Sedimentary Rock Types Characteristics of clastic rocks 6. Lithification: • transformation of loose sediment into a rock • compaction: degree (packing and fusion) http://www.grasp.ulg.ac.be/research/compaction/ PrePost- Compaction - packing http://www.grasp.ulg.ac.be/research/compaction/ Compaction - packing http://www.gly.uga.edu/railsback/PDFimage0208a.jpeg Compaction - grain fusion Sedimentary Rock Types Characteristics of clastic rocks 6. Lithification: • transformation of loose sediment into a rock • cementation: composition silica, calcite, hematite SiO2 CaCO3 FeO2 Quartz grains - Calcite cement http://faculty.gg.uwyo.edu/heller/Sed%20Strat%20Class/SedStratL1/Sedstrat%20gifs/sd1-p11.jpg Plagioclase grains - Calcite cement http://faculty.gg.uwyo.edu/heller/Sed%20Strat%20Class/SedStratL1/slideshow_1_16.htm q-quartz grains, o-quartz cement, c-calcite cement Sedimentary Rock Types Characteristics of clastic rocks 7. Texture: size, shape and arrangement of clasts. Sedimentary Rock Types Characteristics of clastic rocks Three components: • grains: the larger particles (sand and larger) Sedimentary Rock Types Characteristics of clastic rocks Three components: • grains: the larger particles (sand and larger) • matrix: fine clastic particles deposited with grains Sedimentary Rock Types Characteristics of clastic rocks Three components: • grains: the larger particles (sand and larger) • matrix: fine clastic particles deposited with grains • cement: chemical precipitate that fills voids after deposition Levin - Earth Through Time 7th Grains & Cement Grains & Matrix Sedimentary Rock Types Characteristics of clastic rocks 8. Maturity: a measure of how long/far sediment was transported. two kinds Sedimentary Rock Types 8a. Textural Maturity: Immature • large grain size, angular grains, poorly sorted • intermediates • small grain size, well rounded, well sorted Mature Sedimentary Rock Types Characteristics of clastic rocks 8b. Compositional Maturity: Immature - least stable • rock fragments • iron/magnesium minerals • feldspars • quartz Mature - most stable Sedimentary Rock Types Summary most mature least mature well rounded angular grains well sorted poorly sorted fine grained pebbles & sand quartz rock fragments Sedimentary Rock Types Characteristics of Clastic Rocks 1. Grain size 2. Composition of grains 3. Sorting of grains 4. Shape of grains 5. Color of rock 6. Lithification process 7. Texture 8. Maturity a. textural b. compositional Sedimentary Rock Types Environmental significance of sandstones Sedimentary Rock Types Environmental significance of sandstones 1. Quartz arenite: • dominance of quartz • little or no feldspar, mica, or matrix • grains well rounded, well sorted • calcite or silica cement • wide spread thin sand beds http://www.gly.uga.edu/railsback/sands/260Micro900.jpeg Quartz sand Sedimentary Rock Types Quartz arenite : http://nessus.gunslingers.org/2003-09%20-%20North%20Carolina%20Beach%20and%20California%20Hiking/0047%20More%20Beach-half.jpg Sedimentary Rock Types Environmental significance of sandstones Quartz arenite: tectonic setting • Beach, far from the mountains Sedimentary Rock Types Environmental significance of sandstones Arkose: (feldspathic wacke) • contain 25% or more feldspar (pink) • quartz most abundant (angular) • calcite, iron oxide cement, or clay matrix • granitic source • coarse sand, moderately well sorted http://smccd.net/accounts/hand/geology101/sedimentary/images/arkose2.jpg Arkose Sedimentary Rock Types Environmental significance of sandstones Arkose: tectonic setting • Physical weathering near granitic mountain Sedimentary Rock Types Arkose Sedimentary Rock Types Environmental significance of sandstones Wacke: • matrix 30% of rock (dark minerals) • little or no cement • grains supported by matrix http://www.smccd.net/accounts/hand/geology101/sedimentary/images/greywacke1.jpg Wacke Sedimentary Rock Types Environmental significance of sandstones Wacke: tectonic setting • Rapid uplift near continent margin Episodes of deposition Turbidites Episodes of deposition Turbidites One Turbidite http://www.kickkleverlaan.com/ratab%20red.jpg Turbidites Turbidites & Deep Marine Shales Sedimentary Rock Types Environmental significance of sandstones Lithic sandstone: • quartz, mica, chert, rock frag. • little feldspar • 15% matrix or less, rest cement • intermediate rounding & sorting http://staff.aist.go.jp/sudo-gsj/sand/english/D-2444.html Lithic sand (Mekong river) Sedimentary Rock Types Environmental significance of sandstones Lithic sandstone: tectonic setting • delta on the edge of a coastal plain Sedimentary Rock Types Environmental significance of sandstones Lithic sand Sedimentary Rock Types Environmental significance of sandstones Beach far from Mt Continental arid Deep Marine Mature River