chap 4-geology prof edy
TRANSCRIPT
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
1/53
Click to edit Master subtitle style
Luxembourg
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
2/53
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
3/53
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
4/53
EaES 350-6 44
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
5/53
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
6/53
CHAP 3.4 Sedimentary rocksq Sedimentary rocks composed of sediment(derived by weathering process, erodedfrom weathering site, transportedelsewhere & deposited as a loose
aggregate of particles) .q Sediments accumulate at earths surface contain evidence of past events, e.g
environment of particles deposited,mechanisms involved in transported &fossils to study geologic past.q Sedimentary rock important in economic
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
7/53
Formation Sedimentary rocks
Sedimentary rocks are formed of the overburden pressure asparticles ofsediment are deposited out of air, ice, wind, or waterflows carrying the particles in suspension.
As sediment deposition builds up, the overburden pressuresqueezes the sediment into layered solids in a process known aslithification and the original connate fluids are expelled.
Sedimentary rocks are laid down in
layers called beds or strata. Each new layer is laid down horizontally
over older ones in a process
called superposition.
http://en.wikipedia.org/wiki/Overburden_pressurehttp://en.wikipedia.org/wiki/Sedimenthttp://en.wikipedia.org/wiki/Settlinghttp://en.wikipedia.org/wiki/Suspension_(chemistry)http://en.wikipedia.org/wiki/Lithificationhttp://en.wikipedia.org/wiki/Connate_fluidshttp://en.wikipedia.org/wiki/Superpositionhttp://en.wikipedia.org/wiki/Superpositionhttp://en.wikipedia.org/wiki/Connate_fluidshttp://en.wikipedia.org/wiki/Lithificationhttp://en.wikipedia.org/wiki/Suspension_(chemistry)http://en.wikipedia.org/wiki/Settlinghttp://en.wikipedia.org/wiki/Sedimenthttp://en.wikipedia.org/wiki/Overburden_pressure -
8/2/2019 Chap 4-GEOLOGY PROF EDY
8/53
What is diagenesis?
any chemical, physical, or biologicalchange undergone by a sediment after its
initial deposition and during and after itslithification
exclusive of surface alteration (weathering)and metamorphism
http://en.wikipedia.org/wiki/Sedimenthttp://en.wikipedia.org/wiki/Lithificationhttp://en.wikipedia.org/wiki/Metamorphismhttp://en.wikipedia.org/wiki/Metamorphismhttp://en.wikipedia.org/wiki/Lithificationhttp://en.wikipedia.org/wiki/Sediment -
8/2/2019 Chap 4-GEOLOGY PROF EDY
9/53
CHAP 3.4 - Lithificationq Lithification transforming sedimentsedimentary rocks, involved of compactionand/or cementation.q Compaction : from weight of ove rlayingsediment reduce pore spaces & volume.q Cementation : consists of chemicallyprecipitated minerals in pore spaces thatbind the particles. E .g calcium carbonate
(CaCO3), silicon dioxide (SiO2).
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
10/53
COMPACTION
From weight of overlaying sediment compresses the deepersediments.
Reduce pore spaces
Reduce volume.
Compaction occurs as the weight of accumulating sediment forces therock and mineral grains together. This reduces pore space and eliminatessomeof the contained water
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
11/53
Cementation
Cementation is a result of water circulating throughthe pore spaces of a sediment.
If that water carries in it dissolved substances that
then precipitate out during circulation, thosesubstances left behind in the sediments can act ascementing agents.
Calcium carbonate is one of the most commoncements because it is found abundantly in seawater.
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
12/53
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
13/53
CAHP 3.4 Types of sedimentary rocksq Materials accumulating as sediment have 2principle sources:
1. Detrital sedimentary rocks.2. Chemical sedimentary rocks.
q Detrital rock: made up of solid particlesfrom parent material by mechanical &chemical weathering.- All have clastic texture.- Particle size : primary basis to
distinguish the rock & relate to energy of
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
14/53
Figure 2: L ithification of detrital sedim ents.
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
15/53
SHALE Consist of silt and clay,shale covers over half of
sedimentary rocks Particles is the smallest among other type of
DSR
Deposition occurs as a result of gradual settlingfrom nonturbulent conditions. e.g lake,lagoons
Deposition occurred in an oxygen-poorenvironment like swamp,where organic materialsdo not oxidize
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
16/53
SANDSTONE
After shale,sandstone is most abundantsedimentary rock (20 %)
Sorting is degree of similarity in particle sizein a sedimentary rock
Well sorted all grains in sandstone areabout same size
Poorly sorted rock contains mixed largeand small particles
Poor sorting usually result when particles aretransported for a short time and distance andquickly deposited
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
17/53
Shapes of sandstone can also determine the history of sandstone If the transportation is long,the grains lose their sharp edges and become
more rounded. Its because they collide with other grains often enough. If the transportation is short,the grains tend to be more angular Length of trasportation also influence its mineral composition Long trasportation caused gradual destruction of weaker minerals.
e.g feldspar Usually quartz mineral survive the long trip.Thats because the mineral is
very durable Quartz sandstone sandstone that have many quartz mineral Arkrose sandstone contain feldspar,quartz and mica
- poorly sorted and angular
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
18/53
CONGLOMERATE OR BRECCIA
Large enough to be identified as rocktypes
Poorly sorted because contain sand ormud between the grains
If the large particles is angular rather than
rounded, it is calledBreccia Breccia indicate that they did not travel
far before they were deposited
Particles size reveal the strength of thecurrents that carried them
Degree of rounding indicate how far theparticles travelled
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
19/53
CAHP 3.4 Detrital sedimentary rocksq Current: the stronger current, the largerparticle size carried.
- e.g gravel moved by swiftly flowingrivers, landslide & glaciers.q Less energy to transport sand commonfeature as windblown dunes, river deposits
& beaches.q Silt & clay settle very slow associated
with quite water such as lake, lagoon &
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
20/53
CHAP 3.4 Sediment transport & depositionq Sorting refer to particle size distribution
in sedimentary deposit .- Well sorted : all particle about in samesize.- Poorly sorted : wide range of particlesize.
q Rounding process of abrasion that sizeparticles & sharp corner.q Sorting & rounding important aspect in
decipher the history of a deposit .
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
21/53
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
22/53
Figure 1 : Depositional environm ents.
FIG 5.18A - 130
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
23/53
Table 2: Environment of depositi on for detrital rocks.
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
24/53
Conglom erates
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
25/53
Sandstone
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
26/53
Shale
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
27/53
CHAP 3.4 Chemical sedimentary rocks
q Chemical s.r. : Derive from material that iscarried in solution does not remaindissolved in water, some is precipitate toform chemical sediments.
q Chemical processes responsible for theorigin, as when minerals form frominorganic chemical reaction/chemicalactivities of organisms.
q Texture: crystalline (gypsum) & clastic
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
28/53
Limestone
10% of all sedimentary rock Most abundant Composed of calcite (CaCO3) Form by biochemical processes Varies type because form under variety of condition Having 3 types: skeletal limestone, oolitic limestone,microcrystalline limestone
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
29/53
Dolostone Composed of the mineral dolomite (CaMg(CO3)2calcium magnesium carbonate From by direct precipitation from seawater Brownish yellow or light gray Form from biochemical rocks Most is ancient rock React with acid only
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
30/53
Chert Very compact and hard rock made of microcrystallinesilica (SiO2) Hard, dense and typically break like glass Usually white or shades of gray, tan, green, or red
Found in 2 situation- irregularly shape nodules inlimestone or as rock layer Flint- dark colour Jasper- red cause of iron oxide
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
31/53
Evaporates Rock form from evaporation of seawater or salinelake example gypsum (CaSO4.2H2O) have crystalline texture
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
32/53
ORGANIC
SEDIMENTARYROCK
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
33/53
Decay of plants and animal. Accumulation and
lithification of plants andanimals (shell)
Swamp region, sea.
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
34/53
Australia Great Barrier Reef
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
35/53
Limestone
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
36/53
Chalk
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
37/53
Siliceous rock
Composed of silicon dioxide,
(SiO2). Chemical precipitates.
Chert
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
38/53
Chert
Very fine-grained quartz.
Jasper Agate
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
39/53
Chert
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
40/53
Jasper
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
41/53
Agate
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
42/53
Carbonaceous rock
Coal Fossil fuel
Combustible Swamp ecosystem
Exp: lignite
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
43/53
Coal Form from the compaction of plant material
that has not completely decayed is a fossil fuel made more-or-less entirely of organic matterwhich is not crystalline Compose by carbon and sulfur biochemical rock brown or black Light weight
Larger source of fuel
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
44/53
Shale
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
45/53
CHEMICAL SEDIMENTARY ROCKS
Rock Type Composed of Texture
Carbonate
Limestone
Dolostone
Calcite (CaCO3)
Dolomite [CaMg(CO3)2]
Varies
Varies
Evaporite
Rock gypsum
Rock salt
Gypsum (CaSO4.2H2O)
Halite (NaCl)
Crystalline
Crystalline
Cherts Silica (SiO2 ) Crystalline
Coal Carbon from altered land plants -
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
46/53
CHAP 3.4 Sedimentary structures
1. Graded bedding:- show upward decrease in grain size.- form by turbidity current deposition
(underwater flow sediment / water withgreater density than sediment).- current flow downslope reaches flatsea/lakefloor begins deposit large particlefolloed by smaller ones.
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
47/53
Figure 3: Graded- bedding
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
48/53
CHAP 3.4 Sedimentary structures
2. Cross-bedding:- layers are arranged at an angle to thesurface deposited.- found : sand dunes, along shorelines.- cross-bed are inclined downward samedirection of current flow (wind/water).
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
49/53
Figure 4: Cross-bedding
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
50/53
CHAP 3.4 Sedimentary structures
3. Ripple-marks:- small wave of sand that develop onsurface on sediment layer.- current ripple marks :
- asymmetrical in cross section, gentleslope at one side & steep slope at otherside.- current flowing in 1 direction.- wave-formed ripple marks:- symmetrical cross section.- generated by to-and-from motion ofwaves.
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
51/53
Figure 4 : Ripple m arks
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
52/53
CHAP 3.4 Sedimentary structures
4. Mud cracks:- form when clay rich sediment dries &shrink develop intersecting features.- indicate sediment deposited inenvironment where periodic drying tookplace, e.g river floodplain, near lakeshore &muddy deposits exposed along seacoast at
low tide.
-
8/2/2019 Chap 4-GEOLOGY PROF EDY
53/53
Figure 5: Mud cracks