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LithostratigraphyLithostratigraphy
September 27, 2002September 27, 2002
Geology 355, Sedimentology Copyright, 2002, Ron ParkerGeology 355, Sedimentology Copyright, 2002, Ron ParkerGeology 355, Sedimentology , 2002, Ron Parker
LithologyLithology
Is the study and description of the physical
characteristics of rocks.
Also refers to these physical characteristics
Rock type the shale lithology
Color the orange lithology
Mineral Composition the zeolite-bearing litholgy
Grain Size the gravel lithology
Geology 355, Sedimentology , 2002, Ron Parker
StratigraphyStratigraphy
The study of large-scale horizontal and verticalrelationships between units of sedimentary rocks.
Sedimentary units may be defined variously
Lithology
Fossil content
Time and duration of formation Geometry
Geophysical (sonic, radioactive) properties
The study of large-scale horizontal and verticalrelationships between units of sedimentary rocks.
Sedimentary units may be defined variously
Lithology
Fossil content
Time and duration of formation
Geometry
Geophysical (sonic, radioactive) properties
DIGIT, 2001 DIGIT, 2001
Marshak, 2002 Marshak, 2002
Geology 355, Sedimentology , 2002, Ron Parker
StratigraphyStratigraphy Lithostratigraphy Based on rock type.
Biostratigraphy Based on fossils.
Chronostratigraphy Based on time relations.
Sequence stratigraphy Based on geometry of
unconformities.
Magnetostratigraphy Based upon magnetic
properties.
Seismic stratigraphy Based on sound propagation.
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Geology 355, Sedimentology , 2002, Ron Parker
StratigraphyStratigraphy
Cyclostratigraphy Study of sedimentary cycles.
Chemostratigraphy Based upon isotopic signatures.
Basin analysis Stratigraphy and sedimentology are
applied to study basins.
Formation
Infilling
Destruction
Geology 355, Sedimentology , 2002, Ron Parker
Lithostratigraphic UnitsLithostratigraphic Units
Bodies of sedimentary, extrusive igneous,
metasedimentary or metavolcanic rock distinguished
on the basis of physical (lithologic) characteristics.
Stratotype A designated ideal example.
Example: the type Richmondian is Richmond, Indiana
Lithosome Masses of rock that interfinger with
adjacent yet different rocks.
Geology 355, Sedimentology , 2002, Ron Parker
FormationFormation The fundamental lithostratigraphic unit.
Defined as a lithologically distinctive stratigraphic
unit that is large enough in scale to be mappable at
the surface or traceable in the subsurface.
More simply A mappable unit.
Always named for a location.
Geology 355, Sedimentology , 2002, Ron Parker
FormationFormation Formations may be subdivided into:
Members smaller stratigraphic units, which may be
subdivided into
Beds
Formations may be combined into:
Groups, which may be combined into
Supergroups
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Geology 355, Sedimentology , 2002, Ron Parker
Stratigraphic ContactsStratigraphic Contacts
Plane or irregular surfaces between different types of
rocks.
Conformable Formed by unbroken deposition.
Unconformable Represent interrupted deposition with
considerable missing time (known as a hiatus).
Geology 355, Sedimentology , 2002, Ron Parker
Conformable ContactsConformable Contacts
Abrupt contacts
Diastem
Gradational
Progressive gradual contacts
Intercalated contacts
Geology 355, Sedimentology , 2002, Ron Parker
Conformable ContactsConformable Contacts
Abrupt contacts Sharp
boundary between differing
lithologies; represents original
changes in depositional conditions.
Conformable ContactsConformable Contacts
Diastem Minor depositional breaks without erosion. Diastem Minor depositional breaks without erosion.
Geology 355, Sedimentology , 2002, Ron Parker
Conformable ContactsConformable Contacts Gradational Change between lithologies is gradual.
Progressive gradual contacts A uniform change one to
another.
Intercalated contacts Interdigitating transitions from one
lithology to another
Geology 355, Sedimentology , 2002, Ron Parker
Conformable ContactsConformable Contacts Intercalated contacts Interdigitating transitions
from one lithology to another
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Geology 355, Sedimentology , 2002, Ron Parker
Conformable ContactsConformable Contacts
Pinch-outs Beds, members, foramtions that taper to
zero thickness.
Intertonguing Lateral splitting of units
Geology 355, Sedimentology , 2002, Ron Parker
Unconformable ContactsUnconformable Contacts
Unconformity - An unconformity is a gap in the rock
record produced by erosion and/or non-deposition.
An unconformity is significant because it represents
missing TIME.
Geology 355, Sedimentology , 2002, Ron Parker
Unconformable ContactsUnconformable Contacts
Angular unconformity - Tilted rocks are overlain by
flat-lying rocks.
Disconformity Strata on either side of the
unconformity are parallel, with an erosional surface.
Paraconformity Parallel beds, same lithology, no
obvious erosional surface.
Nonconformity Metamorphic or igneous rocks incontact with sedimentary strata.
Angular UnconformityAngular Unconformity
Represents a huge gulf in time.
Sediments deposited horizontally below sea-level.
Sediments deformed by mountain-building event.
Mountains eroded totally away.
Mountain remnants flooded by the sea.
Younger sediments deposited horizontally on the olddeformed sediments.
Represents a huge gulf in time.
Sediments deposited horizontally below sea-level.
Sediments deformed by mountain-building event.
Mountains eroded totally away.
Mountain remnants flooded by the sea.
Younger sediments deposited horizontally on the olddeformed sediments.
DIGIT, 2001 DIGIT, 2001
CorrelationCorrelationNext Class:Next Class:
Geology 355, Sedimentology Copyright, 2002, Ron ParkerGeology 355, Sedimentology Copyright, 2002, Ron Parker
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