Sedimentary Rock Flashcards
<p>Sedimentary Rock</p>
<p>Product of chemical/mechanical weathering</p>
<p>Continental Environment</p>
dominated by stream erosion and deposition
<p>Mechanical Weathering</p>
<p>broken down into smaller pieces,
| Increases surface area for chemical weathering attack</p>
<p>Frost Wedging</p>
<p>Water Freezes in Cracks</p>
<p>Root Wedging</p>
<p>plants grow into fractures</p>
<p>Burrowing animals</p>
<p>move fresh materials to surface</p>
<p>Rock Blasting</p>
<p>Human inmpact</p>
<p>Salt Crystal Growth</p>
<p>sea spray/salty groundwater penetrates crevices and pore spaces, evaporating to form salt crystals enlarging crevices</p>
<p>Sheeting Unloading</p>
<p>•Large masses of igneous rock are exposed by erosion and concentric slabs break loose due to release of confining pressure</p>
<p>Exfoliation Dome</p>
<p>formed after continued weathering causes slabs to separate and fall off</p>
<p>Detrital Rocks</p>
<p>Transported Sediment as Solid Particles</p>
<p>Detrital Cheif Consitituents (4)</p>
<p>clay, quartz, feldspar, micas</p>
<p>Evaporites</p>
<p>triggers deposition of chemical precipitates </p>
<p>Chemical Rocks</p>
<p>consist of precipitated material once in solution</p>
<p>Evaporite Examples</p>
<p>rock salt, rock gypsum</p>
<p>Natural Cements</p>
<p>Calcite, silica, iron oxide</p>
<p>Lithification</p>
<p>Sediments transformed into solid rock by compaction and cemenation</p>
<p>Diagenesis</p>
<p>Chemical. physical biological changes after seediment deposit
</p>
<p>Bowen's Reaction Series</p>
<p>Silicate minerals weather in the same order as crystallization</p>
<p>Speroidal Weathering</p>
<p></p>
<p>Oxidation</p>
(2)
<p>Rusting of iron rich materials for iron oxide
| -slow in dry environments, faster reaction in water</p>
<p>Hydrolysis</p>
<p>Oxidation can only occur after; iron freed from silicate structure</p>
<p>Dissolution</p>
<p>Certain Minerals (halite) dissolve in water</p>
<p>Chemical Weathering</p>
<p>small amount of acid in water increases corrosive force of water, causing dissolution. </p>
<p>sediment</p>
<p>fragmented material</p>
<p>Climate Effect on Weathering (Temperature + Precipitation) 3</p>
<p>
Frequency of freeze-thaw
Moisture available for dissolution
Conditions favoring vegetation growth</p>
<p>Detrital Identification</p>
<p>Particle Size</p>
<p>Chemical Identification</p>
<p>Texture</p>
<p>Stages of Coal Formation</p>
<p>1. Plant material
2. Peat
3. Lignite
4. Bituminous
5. Anthracite
</p>
<p>Coal </p>
<p>composed of organic materials unlike other rocks</p>
<p>Geographic Setting</p>
<p>Determines sediments that accumulate (grain size/shape)</p>
Wind
Eolian
All rocks go to sediment through
weathering and erosion
Sediment turns to SR through
Compaction and Cementation
Most Common Sedimentary Rock
“Shale”
“Shale” (Sedimentary)
Mud-sized particles in thin layers that are commonly referred to as laminae
“Sandstone” Composition (Sedimentary)
Quartz
“Conglomerate” and Breccia” (sedimentary)
Both are composed of particles greater than 2mm in diameter
“Breccia” (Sedimentary)
large angular particles
Conglomerate (Sedimentary)
largely of rounded gravels
Limestone (Sedimentary)
Marine biochemical limestones form as coral reefs, coquina (broken shells), and chalk (microscopic organisms)Inorganic limestones include travertine and oolitic limestone
Most Abundunt Chemical Rock
Limestone
“Limestone” composed (sedimentary)
mineral: calcite
chemical formed secondarily from limestone (sedimentary)
Dolostone
Chert Compositition (Sedimentary)
microcrystalline quartz (CHEMICAL)
Water (Polar)
removes sodium and chlorine from halite crystal faces
Carbonic Acid
Co2 dissolved in raindroms
Calcite attacked by weakly acidic solutions
limestone caverns
Slow Oxidation
Dry Environments
Oxidation Minerals (4)
Ferromagnesium (olivine, pyroxene, hornmblende, biotite)
Oxidation can only occur after
iron freed from silicate structure by hydrolsis
Oxidation
rusting of iron-rich minerals->oxygen/iron to iron oxide
Hydrolsyis primarily
Silicates: clay
Hydrolysis
hydrogen ion attacks and replaces another ion
Spheroidal Weathering
Granite: crystalline rock with joints penetrated, hydrogen replacing K in feldspar, disrupts crystalline structure
What weathers more quickly than silicates?
Carbonates and Halides
Differential Weathering
Uneven (variations in climate)
Chemical MUST have sourced in solutions where as
detrital must have been transported as solids
Coarse
Grave: conglomerate and breccia
Rounded Gravel (Coarse)
Conglomerate
Angular Gravel (Coarse)
Brecia
Medium Particle Size
Sand/Sand Stone
Fine
Mud/Siltstone
Very Fine
Mud/Shale/Mudstone
