Sealevel change

1
(No Transcript)
2
Contents

• Introduction
• Sedimentology concepts
• Fluvial environments
• Deltaic environments
• Coastal environments
• Offshore marine environments

• Sea-level change
• Sequence stratigraphy concepts
• Marine sequence stratigraphy
• Nonmarine sequence stratigraphy
• Basin and reservoir modeling
• Reflection

3
(No Transcript)
4
(No Transcript)
5
Sea-level change

• Relative sea-level change includes a global
  component (eustasy) that is uniform worldwide and
  can be measured relative to a fixed datum (e.g.,
  the center of the Earth), and regional to local
  components (isostasy, tectonism) that are
  spatially variable
• Eustasy involves changes in ocean-basin volume,
  as well as changes in ocean-water volume
  (amplitudes 101102 m)
• Tectono-eustasy (time scales of 10100 Myr)
• Glacio-eustasy (time scales of 10100 kyr)
• Isostasy refers to crustal movements that are a
  direct result of loading and unloading by ice or
  water
• Glacio-isostasy
• Hydro-isostasy

6
(No Transcript)
7
(No Transcript)
8
Sea-level change

• Relative sea-level change includes a global
  component (eustasy) that is uniform worldwide and
  can be measured relative to a fixed datum (e.g.,
  the center of the Earth), and regional to local
  components (isostasy, tectonism) that are
  spatially variable
• Eustasy involves changes in ocean-basin volume,
  as well as changes in ocean-water volume
  (amplitudes 101102 m)
• Tectono-eustasy (time scales of 10100 Myr)
• Glacio-eustasy (time scales of 10100 kyr)
• Isostasy refers to crustal movements that are a
  direct result of loading and unloading by ice or
  water
• Glacio-isostasy
• Hydro-isostasy

9
(No Transcript)
10
(No Transcript)
11
(No Transcript)
12
Sea-level change

• Tectonism includes a vast array of crustal
  movements, ranging from large-scale uplifts and
  basins to small-scale faults
• Steric sea-level changes include density changes
  (temperature, salinity) and dynamic changes
  (atmospheric pressure, ocean currents, wind
  set-up), but these changes are typically on the
  order of a few meters at the most
• The geoid exhibits lows and highs relative to the
  oblate spheroid due to gravity anomalies geoidal
  changes do occur over time, but they are most
  likely slow

13
(No Transcript)
14
(No Transcript)
15
Sea-level change

• Since isostasy and tectonism are spatially
  variable, every geographic location has a unique
  relative sea-level history (RSLEIT)
• Four characteristic RSL-curves associated with
  the last deglaciation
• Near-field sites (e.g., Hudson Bay)
• Ice-margin sites (e.g., Norwegian coast)
• Intermediate-field sites (e.g., mid-Atlantic
  coast)
• Far-field sites (most of the southern hemisphere)

16
(No Transcript)
17
(No Transcript)
18
Sea-level change

• Since isostasy and tectonism are spatially
  variable, every geographic location has a unique
  relative sea-level history (RSLEIT)
• Four characteristic RSL-curves associated with
  the last deglaciation
• Near-field sites (e.g., Hudson Bay)
• Ice-margin sites (e.g., Norwegian coast)
• Intermediate-field sites (e.g., mid-Atlantic
  coast)
• Far-field sites (most of the southern hemisphere)

19
(No Transcript)
20
(No Transcript)
21
(No Transcript)
22
(No Transcript)
23
Sea-level change

• It is believed that eustatic cycles of different
  periods have operated throughout the Phanerozoic
• First-order (108 yr) and second-order (107 yr)
  cycles (primarily tectono-eustatic)
• Third-order (106 yr) cycles (mechanism not well
  understood)
• Fourth-order (105 yr) and fifth-order (104 yr)
  cycles (primarily glacio-eustatic)
• Glacio-eustasy has only controlled limited
  portions of Earth history (e.g., the
  Carboniferous or Late Cenozoic icehouse world as
  opposed to the Cretaceous greenhouse world)
• Whereas RSL change has a profound impact on the
  stratigraphic evolution of numerous sedimentary
  environments (certainly deltaic, coastal, and
  marine), the complex spatial pattern of RSL
  change commonly yields responses that are out of
  phase

24
(No Transcript)
25
Sea-level change

• It is believed that eustatic cycles of different
  periods have operated throughout the Phanerozoic
• First-order (108 yr) and second-order (107 yr)
  cycles (primarily tectono-eustatic)
• Third-order (106 yr) cycles (mechanism not well
  understood)
• Fourth-order (105 yr) and fifth-order (104 yr)
  cycles (primarily glacio-eustatic)
• Glacio-eustasy has only controlled limited
  portions of Earth history (e.g., the
  Carboniferous or Late Cenozoic icehouse world as
  opposed to the Cretaceous greenhouse world)
• Whereas RSL change has a profound impact on the
  stratigraphic evolution of numerous sedimentary
  environments (certainly deltaic, coastal, and
  marine), the complex spatial pattern of RSL
  change commonly yields responses that are out of
  phase