Lecture 15 Lithostratigraphy

1
Lecture 15 Lithostratigraphy
2
Stratigraphy Putting together the whole picture
(processes and history)

• Lithostratigraphy
• Biostratigraphy
• Seismic stratigraphy

• Magnetostratigraphy
• Geochemistry
• stable istopes
• radiometric dating

3
I. Facies (Steno, 1669) aspect or
appearance
Can be genetic (fluvial facies) or descriptive
(sandstone facies)
Lithofacies a consistent lithologic character
within a formation. E.g. an evaporite lithofacies
Walthers law (1894) facies that occur in
conformable vertical successions of strata also
occur in laterally adjacent environments.
4
Transgressions and regressions, progradations
5
Classical interpretation of a cyclothem
6
Assymetry in transgressive and regressive
deposition
7
(No Transcript)
8
II. Accumulation

• Base level. Above sealevel, preservation is the
  exception rather than the rule
• Sediment traps
• tectonic
• basin subsidence
• sea-level rise

9
(No Transcript)
10
III. Gaps

• Diastems obscure, small gaps in the record.
  Barrell (1917)
• Unconformities larger gaps in the record.

11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15
IV. Correlation

• Demonstrating the equivalence or correspondence
  of geographically separated parts of a geologic
  unit

16
Old (pre-1930) and new interpretations of units
in the Devonian Catskills. Layer-cake versus
concept of facies change.
17
An example of time-transgression of lithofacies
from the Everglades
18
(No Transcript)
19
(No Transcript)
20
V. Sequences

• Major unconformities representing Earths broad
  tectonic or eustatic events.

21
Sloss (1963)
22
(No Transcript)
23
VI. Time, Time-Rock and Rock Units

• Time (geochronologic) units
• Eon
• Era
• Period
• Epoch
• Age

• Time-rock chronostratigraphic) units
• Eonothem
• Erathem
• System
• Series
• Stage
• Zone

24
Examples

• Time units
• Phanerozoic eon
• Cenozoic era
• Quaternary period
• Holocene epoch
• Wisconsinan age

• Time-rock units
• Eonothem
• Erathem
• System
• Series
• Stage

25
Rock (lithostratigraphic) units

• Supergroup
• Group
• FORMATION a mappable unit with distinctive
  lithic characteristics
• Member
• Bed