510 likes | 978 Views
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,
E N D
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: Red or Brown: Iron Oxide high O2 (continental)
http://www.visitortips.com/images/gallery/destinations/usa/colorado/denver/fullsize/denver12.jpghttp://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)
Pre- Post- http://www.grasp.ulg.ac.be/research/compaction/ 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
http://faculty.gg.uwyo.edu/heller/Sed%20Strat%20Class/SedStratL1/Sedstrat%20gifs/sd1-p11.jpghttp://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.htmhttp://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
Sedimentary Rock Types Characteristics of Clastic Rocks Grain size Composition of grains Sorting of grains Shape of grains Color of rock Lithification process Texture 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.jpghttp://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.jpghttp://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
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
Lithic sand (Mekong river) http://staff.aist.go.jp/sudo-gsj/sand/english/D-2444.html
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