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ostratigraphy art and science of telling time from rocks. itional core of paleontology, and of geology. geologic time scale s all based on fossils, relative time scale. paleontologists working in industry do biostratigraphy. GG 309 Craig Glenn Spring 2012

Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

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Page 1: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

Biostratigraphy

The art and science of telling time from rocks.

Traditional core of paleontology, and of geology.

The geologic time scale is all based on fossils, relative time scale.

Most paleontologists working in industrydo biostratigraphy.

GG 309Craig GlennSpring 2012

Page 2: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

Biostratigraphy:• Characterization and correlation of rock units

based on fossil content• Based on the recognition that organisms have evolved• Closely linked to paleontology

FossilsIndex Fossils and Fossil Assemblages Good for 3 Things:

• Understanding Evolution• Biostratigraphy (Stratigraphic Correlation)• Environmental Interpretation

UNDERSTANDING THE ENVIROMENTAL CONTROLS IS CRITICAL TO:

• SUCCESSFUL BIOSTRATIGRAPHIC ANALYSIS • SUCCESSFUL INTERPRETATION OF DEPOSTIONAL SYSTEMS

Page 3: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

THE MOST CRITICAL FACTORS AFFECTINGCHRONOSTRATIGRAPHIC SIGNIFICANCE

IN BIOSTRATIGRAPHY ARE:

1. EVOLUTION

2. MIGRATION

3. EXTINCTION

4. ENVIRONMENT

5. PRESERVATION

Page 4: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

EVOLUTION

Ch

arl

es

Darw

in

A. Phyletic gradualism

B. Punctuated equilibrium

Schematic ‘family tree’

Schematic ‘family tree’Morphology(body characteristics)

Morphology

(body characteristics)

RATES?

Gradual

Rapid

In punctuated model, speciation occurs only1000s (100s?) yrs, after population becomes reproductively isolated from the parent population.

Page 5: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

THE TAXONOMIC CLASSIFICATION OF LIFE

- based on # shared characteristics (or differences) -

Carolus Linnaeus

Cover of Linnaeus’ 10th edition of

Systema Naturae (1758)

Animal, Plant, Fungi, Protist, Archaebacteria

single-celled animal-likeProtozoa:Forams & Radiolaria

single-celled plant-likeProtophyta algae:Coccoliths & Diatoms

Page 6: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

Tertiary Sediments of the Gulf Plain

Biostratigraphic Units are Not Lithostratigraphic Units - Not the Same Thing

The Biostratigraphic Unit will correspond to the Lithostratigraphic unit if the fossils are FACIES CONTROLLED.

Page 7: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

INDEXFOSSILS:

ImportantMarineFormsof the Phanerozoic

Methodology

INDEXFOSSILS ARE:

• independentof environment

• short range

• widespread

white bars show total range; black bars show times when imp. Index fossil.

Page 8: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

The Finer Points of Stratigraphy

Page 9: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

Index Fossils:Which One’s Better?

This Classic

The Classic Utilitarian Volkswagen Beetle?(the “people’s car”)

1958 Edsel Beauty?

OR

You decide…

Page 10: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

INDEXFOSSILS:

• independentof environment

• short range

• widespread

Volkswagen Beetle“Type 1”

Protype 1937

“Lookie there, itsgots its darn engine in the back!”

Index Fossil?

Deliberately designed to be as simple as possible mechanically, there was simply less that could go wrong; the air-cooled 985 cm³ 25 hp (19 kW) motors proved especially effective in action in North Africa's desert heat.

A handful of civilian-specific Beetles were produced, primarily for the Nazi elite, in the years 1940–1945, but production figures were small.

1950 VW Convertible

Pseudo-Extinction Species (read Boggs, p. 488). Still, this beetle’s lineage lives on.

1935 KdF-Wagen sp. (Porsche)

The Beetle evolvesBy 1938, the "Beetle" shape had fully evolved. A rigorous testing programme was launched, with men of the feared SS driving a batch of the cars for many thousands of miles through the worst winter weather.

Herbie goes abroad

By 1951, the car was available in 29 countries.

By 1972, 15,007,034 Produced

Page 11: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

The Neputinist approach of Werner

Abraham Werner (1749-1817) Did not agreed with the theory of the catastrophes of the Cuvier. For him, allthe rocks (including the igneous) would have precipitated in a huge global ocean ("neptunisme").

Page 12: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

In furthering Hutton’s magic formula "the present is the key to the past,” Lyell’s book "Principles of Geology" (1830) was a big success.

Charles Lyell (England; 1797-1875)

According to him, the geological processes such as the uplift and erosion operated at a slow and uniform speed. Further, every geological period lasted a long time (eventually hundreds of million years) and the age of the Earth must correspond to a multiple of these long lengths.

See next slide

Page 13: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

Unlike Will Smith, who used fossils as an aid to identify strata, Lyell (and others at the time) recognized the utility of subdividing the Tertiary on the basis of its fossil content alone.

Lyell’s approach was to use the proportions of living and extinct species in the rocks. It is here that fossils became the essential part of subdividing Geologic Time.

(183

3)

Page 14: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

Working in the Jurassic of Europe, Albert Oppel invented the concept of overlapping (aka concurrent) « zones » of fossils and thereby altered for all time the practice of biostratigraphy.

No one since Oppel’s time has been able to devise a more precise and reliable kind of time-stratigraphic fossil zone.

(18

56

)CONCEPT OF THE BIOZONE

Carl Albert Oppel (1831–1865), Germany paleontologist

Boggs,14.2

An Oppel Zone:Overlapping ranges of two or more taxa

Oppel Named his Zones after a particularly distinctive fossil, which he called the Zone’s “Index Fossil.”

Page 15: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

PRINCIPALTYPES OF BIOZONES

Gap Biozone

Biozonesmay begrouped orsubdivided

Named forone or moredistinctivetaxa in it

- An Assemblage Zone is Different - It’s usually a biogeographic group of three or more taxa

- Range of One -An Overlap of Ranges

-Lowest occurrrences(LADs)

Highestoccurrrences(FADs)

GAPZONE

Page 16: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

?

Examples of Correlations based on “Taxon-Range Zones” and “Interval Zones”

Page 17: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

LAD A

A/B Gap Zone

FAD B

FAD C

FAD E

LAD D

C/D Gap Zone LAD C

LAD B

LAD A

FAD C

LAD B

Zone 8 AnotherConcurrent RangeZone

Concurrent RangeZone

Page 18: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

AbundanceBiozones

AKA:Acme Zones

Page 19: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

Time Transgressive Abundance Zones

Page 20: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

Local vs.Total (Global) Range

?

Species F is different ages

in different places?

Page 21: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

Biogeographic Dispersal and Stratigraphic Range

Ocean A Ocean B

TimeinA

Time in B

TOTAL Time in A and B

Barrier

If Total Time is Global, becomes aBIOCHRONOZONE

REMEMBER:• Evolution• Migration• Extinction• Environment• Preservation

Page 22: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

Correlation by Assemblages

Assemblage Zone = Characteristic group of 3 or More Taxa.Commonly, these are environmentally restricted by facies

Boggs, 14.8

Page 23: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

Shaw’s Graphic Correlation Method

What can we do here?

Page 24: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

Shaw’s Method is to plot the heights of the fossil datums in each section

versus each other.

• Here, the correlation line is straight, meaning there was a constant offset in sediment accumulation rates between the sites

• Using the fossil datum correlation line, any part of Section A can be correlated to an equivalent part of Section B.

Page 25: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

Shaw’s Method is to plot the heights of the fossil datums in each section

versus each other.

• The point at 50 m in A corresponds in time to the point at 25 m in B.

• The point at 50 m in B corresponds to 100 m in A!

Page 26: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

Shaw’s Method is to plot the heights of the fossil datums in each section

versus each other.

• The point at 50 m in A corresponds in time to the point at 25 m in B.

• The point at 50 m in B corresponds to 100 m in A!

So, what exactly is the relative rate of sedimentation between these two sections?

Answer: y = mx +b or, rate in A = 2 times rate in B

Page 27: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

But, what is there if the sedimentation rate changes in one section relative to the other section?

What if there are unconformities?

Or….

Page 28: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

See Nichols, Fig. 20.5

Deposition stops in “A” while continuing in “B”

“A” speeds up OR “B” slows down

Shaw

Dia

gra

ms

to t

he R

esc

ue!

Page 29: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

Globorotalia truncatulinoides

WarmCold

1.5

Ma

A prelude to Oxygen Isotope Stratigraphy: Planktonic Foraminiferal Coiling Ratios

Page 30: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

TEMPORAL RESOLUTION ISSUES

Go Steve Go!

Page 31: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based

RELATIVE STRATIGRAPHIC RESOLUTIONBIOCHRONOLOGIC VS RADIOMETRIC DATING

Average biochronologic resolution: 1 Ma Typical uncertainty range of radiometric dating: 1% - 10%

Biochronological precision exceeds isotopic dating methods for most of Phanerozoic. Isotopic dating, however, is used to calibrate ages of biostratigraphic zones and convert zonal schemes to an equal-interval time scale, an objective that can not be achieved by fossils alone.

Mioc

ene

Cretaceous

1 Ma

Precambrian

(From Taylor, A. , 1987, Stratigraphic Resolution)

Page 32: Biostratigraphy The art and science of telling time from rocks. Traditional core of paleontology, and of geology. The geologic time scale is all based