Type s o f fo s s ilizatio n c arbo nizatio n c he m

Type s  o f fo s s ilizatio n
C arbo nizatio n
•
c he m ic al re ac tio n whe re  wate r trans fo rm s  the  o rg anic
m ate rial o f plant o r anim al to  a thin film  o f c arbo n.
•
Nitro g e n, hydro g e n, and o xyg e n are  drive n o ff as  g as e s ,
le aving  an o utline  o f the  o rg anis m .
•
fis h, le ave s  and the  wo o dy tis s ue s  o f plants .
Mo lds
Ho w are  fo s s ils  pre s e rve d?

Type s  o f fo s s ilizatio n
•
Trac e  fo s s ils
•
trac ks
•
trails
•
burro ws
•
bo ring s
Ho w are  fo s s ils  pre s e rve d?

Appropriate characteristics of
fossils used for correlation
(Zone Fossils)(1)
•
Easily preserved
–
bones and shells, not jellyfish!
•
Easily identified
–
distinctive characteristics, as with ammonites,
that are better than freshwater clams

Appropriate Characteristics of
Zone Fossils (2)
•
Abundant
–
forams are better than dinosaurs
•
Geographically widespread
–
to enable long distance correlation
•
Environmentally tolerant
–
facies independent

Commonly used groups of
fossils include:
•
graptolites, trilobites (Paleozoic)
•
corals, brachiopods (Paleozoic)
•
goniatites (Paleozoic)
•
ammonites (Mesozoic)

Commonly used groups of
fossils include:
•
microfossils
–
calcareous nannofossils (Cretaceous &
Cenozoic)
–
conodonts (Paleozoic)
–
forams (Cenozoic)
–
pollen and spores

Petroleum Micropaleontology
•
The petroleum industry uses microfossils
(particularly forams) because they are
small and abundant, so that large
numbers can be recovered from well
cuttings