Please enable JavaScript.
Coggle requires JavaScript to display documents.
Core Analysis (Biostratigraphic event causes (Biostratigraphic events =…
Core Analysis
Biostratigraphic event causes
Biostratigraphic events =
Extinctions
Origin of species
Driver = evolution
Phylogeny
required
Must know how species relate to eachother
Date with magnetostratigraphy
Relate biodiversity to environment
K-T boundary = distinctive everything disappears ...
Microfossils
used for dating
diatoms
radiolaria
dinoflagellates
forams
coccoliths
Coccolithophores
phytoplankton
spec. photosynthetic algae
coccoliths overlap & cover cell
each species has slightly different coccoliths
Nanofossils
cells decompose - coccoliths fall to seafloor
Rapid turnover = important
precise dating tools since lotsa biostratigraphic events
Coccolithophore phylogeny e.g.
based on morphological observations
one pattern of family evolution
structure simplification
character loss
accuracy (compare to molecular genetic)
tenuous relations btwn families/groups
family/group relations supported
Absolute Dating
Magnetostratigraphy
Fe-rich particles align with ambient magnetic field on crystallisation
Polarity reversals of crustal rocks result over time
Older rock to edges of basins
Radiometric Dating
Radiometrically date isotopes
Zr/Ar/K
from minerals in the crust or sediment
Applying magnetostratigraphy
Equivalent age sediment lies on equivalent age crust
Know date of reversals
Sediment & crust produced at similar rate
Can extrapolate date of bioevent
Record distance of biostratigraphic event from polarity reversal
Reversals dated radiometrically
CORE 1. Record polarity reversal at beginning of core
CORE 2. Use sedimentation rate & distance of bioevent from start/end of core
Correlate radiometric date with biohorizon accounting for sedimentation rate and distance
CORE 3. Calculate & extrapolate date of bioevent
1) Dating with microfossils
Date with all groups of microfossils present
Cross-referencing acts as safety net
Not all groups found in all environments
3) Magnetostratigraphy
Study alignment of Fe-rich mineral particles with magnetic pole through time
Polarity reversals allow date biostratigraphic events
Phytoplankton
Infer Productivity
Phytoplankton allow inferences about oceanic productivity
Gauge from phytoplankton diversity
Coccolith/foram Importance
Turnover very rapid
Lots of biostratigraphic events (speciation & extinction )
Allows very precise dating
Phylogeny
connections between all groups of organisms
understood by descendent/ ancestor relationships
2) Describe Sedimentology
Could be hiatus in sedimentology