Transcript Seds&Basins-Ch05-Stratigraphy

Sedimentary Geology
Geos 240 – Chapter 5
The Principles of
Stratigraphy
Dr. Tark Hamilton
Camosun College
Correlation of Stratigraphy
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This mainly works for bedded Sedimentary rocks
Correlation of rocks, beds, successions, fossils
Lithology: Lithostratigraphy
Biostratigraphy: widespread but short lived fossils
Chronostratigraphy: zircons, igneous tephra/dyke
Allostratigraphy: unconformity bounded packages
Sequence Stratigraphy: cycles, eustatic, genetic
Absaroka Series
Stratigraphy of
Northern Ellesmere Island, Nunavut
Atlantic Opens
Kaskaskia Series
Iapetus Closes
(Missing Permian)
Bayou-Delta Facies
Givetian to Fammenian: Tiktaalik
Origins of Stratigraphy: Founders I
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~1550CE Leonardo da Vinci: Tethyan marine fossils
in Italian alps
1669 CE Nicolaus Steno: Original Horizontality,
Superposition (younger on top of older beds)
~1750 CE James Hutton: Uniformitarianism
(gradualism), Geological cycles (uplift/tilting, erosion.
Sedimentation) & Deep Geological Time
~1815 CE William Smith: Principle of Faunal
Succession, one of earliest Geological maps, Strata of
England and Wales
Origins of Stratigraphy: Founders II
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~1842 Alcide d’ Orbigny: Biological stages 10 – 100 Ma,
evolution based assemblages. Crude biostratigraphy.
~1856 Albert Oppel: Biologic zones = range of a specific
organism, higher resolution biostratigraphy.
~1917 Joseph Barrell: Base level or sea level changes will
result in breaks (unconformities) genetic strat.
1963 Larry Sloss: Subaerial unconformities bound
stratigraphic sequences. Allostratigraphy
~1960’s Harry Wheeler: Time distance diagrams: duration,
extent and hiatus in strat. Sequences
1977 Peter Vail: Global Eustatic Sea Level changes & Global
correlations on seismic strat. Who needs biostrat, local basins?
William “Strata” Smith: 1769-1839
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Principal of
Stratigraphic
Association of Fossils
(faunal succession)
1815 1st Geological Map
of England
Canal Surveyor
1st Wollaston Medalist
of the Geological
Society of London
Cross Section of London Basin
Jerome Harrison, 1882
Following in the footsteps of William “Strata” Smith
Correlation of Stratigraphy
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Comparing & connecting stratigraphic
successions between localities: trenches, cliffs,
boreholes or across and between basins
Lithology: Lithostratigraphy, Original Triassic, 3
distinctive beds across the Alps. (Alberti’s Trias
referred to the division of these strata into three
units: the Bunter [or Buntsandstein],
Muschelkalk (Limes), and Keuper (Marls),
known as the “Germanic facies,” is mainly
Continental. The type sections are now more
widespread Marine facies based on ammonoids.
Muschelkalk-Keuper Boundary:
Winterswijk Netherlands: H.W. Oosterink et al 2006
Marls/Black Clays
Rhaetian/Liassic
Muschelkalk
Limestones
(Buntsandstein
Unexposed)
Correlation of Stratigraphy
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Biostratigraphy: widespread but short lived fossils
Relative ages requires statistical numbers of fossils
 Only good to +/- 1Ma (the average species lifespan)
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Chronostratigraphy
Absolute radiometric dates from: zircons, apatites,
igneous events, tephra-ash beds, U-Pb or 39Ar/40Ar
 Magnetic Reversal Stratigraphy ≤ Cretaceous
 Marine Stable Isotope: H/D, 16O/18O, 32S/34S, 12C/13C
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Allostratigraphy: unconformity bounded packages
Sequence Stratigraphy: cycles, eustatic, genetic
1800’s Faunal Succession & Correlation:
Stephanoceras and Micraster
Lower Jurassic (Midlands) & Upper Cretaceous Chalk
Ammonite (Cephalopoda) & Echinoid (Heart Urchin, Echinodermata)
Biostratigraphy
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Dozens to hundreds of species
Gradual structural changes  evolution
Biozones (time), Stages (evolutionary differentiation)
Picky species nail the environment, quiet, rough, O2
FAD: First occurrence datum
Coincident Range (Concurrent species)
LAD: Last Occurrence Datum
Biocenose assemblages (living ecologies)
Thanatocenose assemblages (enviro-accumulations)
Chronostratigraphy
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Post WWII, Harold Urey, U.Chicago, Solid Source
Mass Specs, 238U  206Pb, 87Rb 87Sr & 87Sr/ 86Sr,
Deuterium, Precambrian Atmosphere, Nobel Prize
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Thermochronometry, Derek York U of T : Lunar
rocks, Ar-39/40, thermal blocking temperatures
Chronostratigraphy: Radio-isotopes
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U/Pb clocks from Zircon & Baddeleyite for
Precambrian sediments, igneous cores & meta rims
Rb/Sr for intercalated Volcanics or feldspars for
Mesozoic and older rocks (due to long half life and
low Rb/Sr ratio)
K/Ar for Pliocene and older Volcanics
39/40Ar some sedimentary minerals like Glauconite
or Fission Track for Pleistocene and older Volcanics
Disequilibrium Uranium series isotopes (Ra for Ca)
for Pleistocene & older Carbonates, reefs,
speleothems
Radioactive fallout correlation dating: 137Cs, 90Sr
Allostratigraphy (Larry Sloss, 1963)
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Major Unconformities bound packages of stratigraphy
which correlate across and between continents
Caused by tectonic and global eustatic events, 10-100
Ma long for North America:
Zuni
 Absaroka
 Kaskaskia
 Tippecanoe
 Sauk
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Later Peter Vail of Exxon extended this to the Atlantic Basin
mainly on eustatics alone & Seismic Sequence Stratigraphy
Stratigraphic Variability for a
Hypothetical Lithostratigraphy
Relative Datum
flattened
Shale line to right edge
Log Shape Analysis:
Wiggle Matching
SP or Resistivity
2 Methods of Defining Stratigraphy
Ordovician
Cambrian
Paleocene (Tertiary)
Maastrictian (Cretaceous)
Cow Head Breccia: Green Point Newfoundland
K/T Boundary Clay, Frenchman Valley, Saskatchewa
A) Nothing Happened or B) Widespread Distinctive Event
Zuni
Absaroka
Kaskaskia
Tippecanoe
Sauk
Allostratigraphic Breaks in Rift Basin
Formations are Lithostratigraphic
Subdivision of Regional CambroOrdovician Strata: by Litho & Allostrat.
Tippecanoe is Upper Ordovician – Silurian over
Sauk = Upper Cambrian – Middle Ordovician
Biozones
Biozones: Maastrichtian Chalk NW Europe
# = Species
Concurrent Range
Biozones