209 20 10
TRANSCRIPT
![Page 1: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/1.jpg)
UNIVERSITY OF CALGARY SPRING 2010
GLGY 209-20 INTRODUCTION TO GEOLOGY I
![Page 2: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/2.jpg)
Oxic/anoxic conditions
Oxic conditions: benthic organisms at the bottom of the ocean destroy the dead organisms: low chances to fossilize.
Anoxic conditions: no benthic organisms at the bottom of the sedimentary basin: high chances to fossilize.
![Page 3: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/3.jpg)
Example of burrowing process
Bivalve burrowers in a coral colony (recent faunas of the Bahamas).
![Page 4: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/4.jpg)
Example of burrowing process
Carbonate mud sediments at a water depth of about 5 meters; note the presence of burrows of the crustacean Callianassa; Cat Bay, Bahamas.
Carbonate mud stabilized sediments at a water depth of about 1.5 meters; Cockroach Island, Bahamas.
![Page 5: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/5.jpg)
Exceptional preservation
•Cambrian sediments of British Columbia (western Canada)
• Burgess Shale
![Page 6: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/6.jpg)
Lagerstatten – Crato Formation of Brazil (approx 110 m.y.)
Insect wings (left) and a roach wing (right). The right image is acid-prepared.
![Page 7: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/7.jpg)
Lagerstatten – Crato Formation of Brazil (approx 110 m.y.)
Various scorpion species (Protoischnurus and Araripescorpius).
![Page 8: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/8.jpg)
Lagerstatten – Crato Formation of Brazil (approx 110 m.y.)
Fossil insect showing preserved color pattern on the wings – Baecossus.
![Page 9: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/9.jpg)
Kinds of fossils
Body fossils: direct or altered remains of ancient organisms (e.g., teeth, shells, tests, etc).
Trace fossils (ichnofossils): evidence of the activity of ancient organisms.
Chemical fossils (biomarkers): organic compounds produced by various organisms, which are found in strata.
![Page 10: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/10.jpg)
Examples of body fossils
Left: crinoid with the calcareous plates in anatomical connection and corals.
Right: cluster of brachiopods.
![Page 11: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/11.jpg)
Example of trace fossil
Example of a trace fossil of a trilobite; the trilobite body is not preserved.
![Page 12: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/12.jpg)
Examples of trace fossils
Flying traces: multiple looping trails generated by a flying insect caught on surface with a thin film of mud or water.
Beetle traces: moving traces of an insect (Scoyenia).
![Page 13: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/13.jpg)
Examples of trace fossils
Left: root casts (rhizoliths) in an ancient
soil (Spain).
Right: reconstruction of a modern crayfish burrow (height = 0.7 m).
![Page 14: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/14.jpg)
Kinds of fossil preservation Recrystallization; Moldic preservation of mold-cast
preservation; Perminerallization; Carbonization; Congelation; Fossilization in amber.
![Page 15: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/15.jpg)
Recrystallization
This process involves the conversion of the original minerals of the test into a different mineral.
The most common transformation during the process of recrystallization is that from aragonite to calcite.
Aragonite and calcite are two carbonates (CaCO3) but with different crystal structures.
![Page 16: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/16.jpg)
Moldic preservation
The original test or shell is dissolves; example of a gastropod; the shape of the former organism is given by the lithified sediment infill.
The mold (right) and cast (left) of a trilobite; note that the original material was dissolved.
![Page 17: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/17.jpg)
MP - ReplacementReplacement is rather a particular case of moldic (mold and cast) preservation, in which the space resulted from the dissolution of the original test is filled by a new mineral.
Pyritization is the most frequent (and spectacular) case of replacement.
![Page 18: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/18.jpg)
PermineralizationPermineralization results from the filling of the pore spaces usually by opal or chalcedony (SiO2).
![Page 19: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/19.jpg)
Carbonization
A kind of fossilization often met in plants and algae, but also in fishes.
Occurs when the fossils are buried deep into the Earth’s crust and all the organic material is expelled, excepting for the carbon.
These fossils have a blackish appearance.
![Page 20: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/20.jpg)
CongelationThis kind of fossilization occurs at high latitudes, where there is a thick layer of frozen soil and rock at the uppermost part of the Earth’s crust.
![Page 21: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/21.jpg)
Fossilization in amber
A salamander, a frog and a snail fossilized in amber. Amber is a natural resin, which allow three dimensional fossilization of the organisms caught while it is still liquid (high viscosity).
![Page 22: 209 20 10](https://reader036.vdocuments.us/reader036/viewer/2022062513/55508d5fb4c905235b8b4f20/html5/thumbnails/22.jpg)
Tar PitsTar pit in California from which were recovered excellently preserved fossils that lived in this area during the past 40,000 years.