Sedimen - Lithostratigraphy

8/2/2019 Sedimen - Lithostratigraphy

1/4

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


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.


2/4


StratigraphyStratigraphy

Cyclostratigraphy Study of sedimentary cycles.

Chemostratigraphy Based upon isotopic signatures.

Basin analysis Stratigraphy and sedimentology are

applied to study basins.

Formation

Infilling

Destruction


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.


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.


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


3/4


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).


Conformable ContactsConformable Contacts

Abrupt contacts

Diastem

Gradational

Progressive gradual contacts

Intercalated contacts



Abrupt contacts Sharp

boundary between differing

lithologies; represents original

changes in depositional conditions.


Diastem Minor depositional breaks without erosion. Diastem Minor depositional breaks without erosion.


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


Conformable ContactsConformable Contacts Intercalated contacts Interdigitating transitions

from one lithology to another


4/4



Pinch-outs Beds, members, foramtions that taper to

zero thickness.

Intertonguing Lateral splitting of units


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.


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

Sedimen - Lithostratigraphy

Documents