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How How does sediment turn into rock?
– Compaction – Cementation – Crystallization All processes remove pore space between pore grains. 5 Lithification of Sediments
– Reduces the volume of sediment Cementation of Rocks
– Minerals precipitate between grains as groundwater moves through pore spaces Cementation of Rocks
Pore space Calcite cement Shells Lithification of Rocks
– Minerals precipitate from solution to form entire rock body. (Ex: Limestone) Photomicrograph Types of Sedimentary Rocks
– Fragments of sedimentary, metamorphic, and igneous rocks cemented together Groups of Sedimentary Rocks
– Consist of fragments of sedimentary, metamorphic, and igneous rocks – Pieces can have sizes from fistfistsize to barely visible: classification - names – Silicates
There There are lots of them Resistance Resistance to weathering (quartz) Chemical Chemical (inorganic)
– Precipitants from dissolved minerals
Limestone, Limestone, Halite Biochemical Biochemical (organic)
– Plants and animal shells or skeletons
Coal Coal 6 Detrital Rocks
– Grains are rounded Detrital Rocks
– Silicate minerals – 0.64 – 2 mm – Quartz sandstone (Arenite)
> 90% Quartz 90% Breccias Breccias
– Grains are angular – Feldspathic sandstone (Arkose)
~ 25% Feldspar 25% ~ 75% Quartz 75% – Lithic sandstone (Graywacke)
~ 25% dark fragments (volcanic) 25% ~ 20-30 % Feldspar 20~ 45-65% Quartz 45- Detrital Rocks
– Like mudstone, but grains barely visible Mudstone Mudstone - Shale
– Clay minerals and mica – < 0.004 mm (not visible) – Low energy
Lake, Lake, lagoon, floodplains, deep marine Shale exposure Chemical and biochemical sedimentary Rocks
Consist Consist of ions and compounds released by chemical weathering
– precipitated by chemical reactions (inorganic) or by – metabolism of organisms (organic) Chemical and biochemical sedimentary Rocks
– Very fine grained – Limestones
Calcite Calcite Bahamas Bahamas and Florida Caves Caves – Evaporates
Halite Halite Gypsum Gypsum 7 Salt lake: formation of evaporites Salt lake: formation of evaporites 8...
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This note was uploaded on 05/18/2011 for the course GEOL 105 taught by Professor Jack during the Spring '08 term at University of Louisiana at Lafayette.
- Spring '08