BASINS Flashcards
1
Q
Ideal conditions for exceptional preservation
A
- rapid burial
-prevents breakage,
scavenging and decay - low energy
-prevents breakage - anaerobic and anoxic
-no decay as no aerobic
bacterial action - low pH
-decay is slowed - fine grained sediment
-detail is preserved - original material replaced early in diagenesis
-less alteration of original
material so fine details are
preserved
2
Q
Lagerstätten deposits
A
A sedimentary deposit with a large number of fossils
Konzentrat (concentration)
- many organisms in one bed
- e.g high conc of fossils on reefs
Konservat (conservation)
- known for exceptional preservation
- e.g Burgess shales
3
Q
Solnhofen limestone
A
Southern Germany, 140Ma - mid-jurassic
- terrestrial and marine organisms
-Archaeopteryx - necrolytic features
- hypersaline due to evaporation
-toxic - no scavengers - shallow inland sea with reefs and lagoons - oxic surface, anoxic deeper
-no bacterial decay - rapid deposition of fine-grained muds
4
Q
Burgess shales
A
Canadian Rockies, 508 Ma - mid-Cambrium
- Evidence of cambrium explosion
- trilobites
- deep tropical basin
-sea was oxic as trace fossils
present, sediment anaerobic - benthonic in-situ preservation
-entombed by turbidity
current - in life position - soft tissue was preserved
-limbs, gills, etc
5
Q
Chengjiang
A
Yunnan province China, 518Ma - lower cambrium
- better evidence of cambrium explosion
- benthonic in-situ preservation
-buried in turbidity current - shallow tropical shelf
-low energy - no disarticulation - soft tissue preserved as aluminosilicate film
- influxes of fresh water helped preservation
-altered sea water chemistry - shows cyclic sedimentation
-alternating grey-green to
yellow shales
6
Q
Ediacaran
A
Ediacaran Hills Australia, 550Ma - precambrium
- soft bodied, sessile organisms
-oldest multicellular organisms - rapid evolution after snowball earth
- avalon explosion
- imprints in sandstone
-fine detail preserved
