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13 Cards in this Set
- Front
- Back
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Name the 5 main biozone types |
Range biozone Concurrent range biozone Partial range biozone Consecutive range biozone Assemblage biozone (Acme biozone?) |
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What are the characteristics of a good zone fossil |
Independent of environment Rapidly evolving Geographically widespread Abundant Widespread Easily recognisable |
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Use a named example for a good zone fossil |
Ammonites .Cretaceous ammonia morphotypes & water depth .Can be used to correlate biostratigraphical units, 20,000 years .Distinctive she'll shape |
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Name 3 rifting models |
Pure shear model - McKenzie 1978 Simple shear model - wernike 1981 Crustal delamination model - lister 1986 |
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What factors are key for identifying synrift |
Reflectors diverge towards normal fault Older reflectors dip more towards fault than younger ones Possible onlap up-dip of hanging wall |
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What does TEX-86 stand for |
Tetra-ether index of lipids with 86 carbon atoms Picoplankton Crenarchaeota |
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What does U37 (k) index stand for |
Long chain di-, tri- & tetra-unsaturated methyl & ethyl ketones found in Oceanic sediments. 37= 37 carbon atoms U= underestimated K= ketone |
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What are the assumptions used for the U37(k) index |
.Temperature relationship consistent over time. .No preferential loss of c37:2/:3 .Calibration can be applied to all regions at all times in the geological past |
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What are the advantages of using U37(k) |
.Alkenones are relativelt stable in the sed column .Technique can be used in most oceanographic settings .Analysis is straightforward & inexpensive .Long temporal records from marine sediments |
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What are the potential problems of using U37(k) index |
Sediment mixing Degradation in the sediment column Evolution |
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Define biostratigraphy |
Element of stratigrapht that deals with the distribution of fossils in the stratigraphic record & organisation of strata into units based on fossil content. |
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Define chemostratigraphy |
Uses chemical indicators to characterise stratigraphical sucessions & provide correlations to a standard chronostratigraphical time scale. |
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What elements are often used in chemostratigraphy |
Carbon Oxygen Strontium |
