EaES455-7.ppt

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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

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Sea-level change

• Relative sea-level change includes a global component(eustasy) that is uniform worldwide and can be measuredrelative to a fixed datum (e.g., the center of the Earth), andregional 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 ~101 – 102 m)

• Tectono-eustasy (time scales of 10 – 100 Myr)

• Glacio-eustasy (time scales of 10 – 100 kyr)

• Isostasy refers to crustal movements that are a direct result of loading and unloading by ice or water• Glacio-isostasy

• Hydro-isostasy

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Sea-level change

• Relative sea-level change includes a global component(eustasy) that is uniform worldwide and can be measuredrelative to a fixed datum (e.g., the center of the Earth), andregional 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 ~101 – 102 m)

• Tectono-eustasy (time scales of 10 – 100 Myr)

• Glacio-eustasy (time scales of 10 – 100 kyr)

• Isostasy refers to crustal movements that are a direct result of loading and unloading by ice or water• Glacio-isostasy

• Hydro-isostasy

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Sea-level change

• Tectonism includes a vast array of crustal movements, rangingfrom large-scale uplifts and basins to small-scale faults

• Steric sea-level changes include density changes (temperature,

salinity) and dynamic changes (atmospheric pressure, oceancurrents, wind set-up), but these changes are typically on theorder of a few meters at the most

• The geoid exhibits lows and highs relative to the oblatespheroid due to gravity anomalies; geoidal changes do occur

over time, but they are most likely slow

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Sea-level change

• Since isostasy and tectonism are spatially variable, everygeographic location has a unique relative sea-level history(RSL=E+I+T)

•

Four characteristic RSL-curves associated with the lastdeglaciation:

• 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)

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Sea-level change

• Since isostasy and tectonism are spatially variable, everygeographic location has a unique relative sea-level history(RSL=E+I+T)

•

Four characteristic RSL-curves associated with the lastdeglaciation:

• 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)

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Sea-level change

• It is believed that eustatic cycles of different periods haveoperated 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 Earthhistory (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 (certainlydeltaic, coastal, and marine), the complex spatial pattern of RSLchange commonly yields responses that are out of phase

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Sea-level change

• It is believed that eustatic cycles of different periods haveoperated 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 Earthhistory (e.g., the Carboniferous or Late Cenozoic icehouse worldas opposed to the Cretaceous greenhouse world)

• Whereas RSL change has a profound impact on the stratigraphicevolution of numerous sedimentary environments (certainlydeltaic, coastal, and marine), the complex spatial pattern of RSLchange commonly yields responses that are out of phase

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EaES455-7.ppt