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Example: mapping depocenters through time (view source)
Revision as of 19:06, 30 January 2014
, 19:06, 30 January 2014Initial import
{{publication
| image = exploring-for-oil-and-gas-traps.png
| width = 120px
| series = Treatise in Petroleum Geology
| title = Exploring for Oil and Gas Traps
| part = Critical elements of the petroleum system
| chapter = Sedimentary basin analysis
| frompg = 4-1
| topg = 4-123
| author = John M. Armentrout
| link = http://archives.datapages.com/data/specpubs/beaumont/ch04/ch04.htm
| pdf =
| store = http://store.aapg.org/detail.aspx?id=545
| isbn = 0-89181-602-X
}}
Mapping age-specific isopach thicks in the northern GOM basin defines laterally shifting sites of maximum deposition (Figure 4-4). Methods of mapping are clearly presented in Tearpock and Bischke.<ref name=ch04r94>Tearpock, D., J., Bischke, R., E., 1991, Applied Subsurface Geologic Mapping: Prentice-Hall, 648 p.</ref>
==GOM basin depocenter time intervals==
In the northern GOM basin, depocenters prograde (Figure 4-4) over the transitional crust (Figure 4-6) and deform the underlying salt into a complex network of salt-cored anticlines and salt-withdrawal synclines (Figures 4-8, 9). Late Neogene depocenters of the Mississippi River, the largest source of sediment to the northern Gulf of Mexico, developed during five time periods from the latest Miocene through Holocene (from ;<ref name=ch04r75>Piggott, N., Pulham, A., 1993, Sedimentation rate as the control on hydrocarbon sourcing, generation, and [[migration]] in the deepwater Gulf of Mexico: Proceedings, Gulf Coast Section SEPM 14th Annual Research conference, p. 179–191.</ref> see also .<ref name=ch04r38>Goldthwaite, D., 1991, Central Gulf Coast stratigraphy, in Goldthwaite, D., ed., An Introduction to Central Gulf Coast Geology: New Orleans Geological Society, p. 17–30.</ref> Following are the five depocenter intervals and their time periods.
{| class = "wikitable"
|-
! Interval
! Time period, ma
|-
| A
| 6–4
|-
| B
| 4–3
|-
| C
| 3–2.5
|-
| D
| 2.5–1
|-
| E
| 1–Present
|}
Figures 4-13 to 4-16 are maps of depocenters and paleogeography for intervals A, B, D, and E. These were constructed by correlating wells using fossil extinction events and grids of interpreted seismic reflection profiles. The High Island–East Breaks study area is shown on each map.
[[file:sedimentary-basin-analysis_fig4-13.png|thumb|{{figure number|4-13}}After Piggott and Pulham<ref name=ch04r75 />). Copyright: Gulf Coast Section SEPM.]]
[[file:sedimentary-basin-analysis_fig4-14.png|thumb|{{figure number|4-14}}After Piggott and Pulham<ref name=ch04r75 />). Copyright: Gulf Coast Section SEPM.]]
[[file:sedimentary-basin-analysis_fig4-15.png|thumb|{{figure number|4-15}}After Piggott and Pulham<ref name=ch04r75 />). Copyright: Gulf Coast Section SEPM.]]
[[file:sedimentary-basin-analysis_fig4-16.png|thumb|{{figure number|4-16}}After Piggott and Pulham<ref name=ch04r75 />).]]
==Formation of high island-east breaks depocenter==
Between 2.5 and 2.0 Ma, the major northern GOM basin depocenter was focused offshore of western Louisiana and eastern Texas. The westernmost part of this depocenter appears to have been the input area for the ancestral Mississippi River system. The resulting depocenter, the High Island–East Breaks depocenter, has more than [[depth::16,000 ft]] (4875 m) of late Pliocene and early Pleistocene sediments deposited during a succession of highamplitude sea level cycles.
==Timing of petroleum generation==
Each of the isopach maps in this section is annotated with the area of active petroleum generation and migration. These comments are based on the [[modeling]] of Piggott and Pulham<ref name=ch04r75 />), illustrated and discussed along with Figures 4-32 and 4-33.
[[file:sedimentary-basin-analysis_fig4-32.png|thumb|{{figure number|4-32}}After Piggott and Pulham<ref name=ch04r75 />). Copyright: Gulf Coast SEPM.]]
[[file:sedimentary-basin-analysis_fig4-33.png|thumb|{{figure number|4-33}}After Piggott and Pulham<ref name=ch04r75 />). Copyright: Gulf Coast SEPM.]]
==Interval A paleogeography==
The figure below shows the paleogeography of the Mississippi River depositional system from approximately 6 Ma to 4 Ma (interval A). Deposition consists of net sand isopach thicks on the shelf and intraslope basins that are interpreted to be deepwater “fan” complexes.
==Interval B paleogeography==
This figure shows paleogeography from approximately 4 Ma to 3 Ma (interval B). Shelf and intraslope basin thicks are potentially sand prone. (Note the shift westward from the previous depocenter location.)
==Interval D paleogeography==
The following figure shows paleogeography from approximately 2.5 Ma to 2 Ma (interval D). Again, shelfal net sand thicks and intraslope basin isopach thicks interpreted to be deepwater “Tan” complexes are the dominant depositional environments. Note the depocenter has shifted to offshore western Louisiana and Texas. The High Island-East Breaks study area occurs within the western part of this depocenter.
==Interval E paleogeography==
The paleogeographic map below represents time from about 1 Ma to the present (interval E). Canyons are interpreted from incised and back-filled geometries on seismic reflection profiles. Note the depocenter has shifted back to offshore eastern Louisiana from the preceding location offshore eastern Texas/western Louisiana.
==Depocenter summary==
Mapping age-specific isopach thicks defines laterally shifting sites of maximum deposition along the margin of the basin. Each of these depocenters has a unique history of accumulation with consequent variations in [[maturation]], migration, and entrapment histories. Evaluation of depocenter maps should include comparison of the results with the largerscale isopach maps (Figures 4-3, 4-4).
[[file:sedimentary-basin-analysis_fig4-3.png|thumb|{{figure number|4-3}}.]]
[[file:sedimentary-basin-analysis_fig4-4.png|thumb|{{figure number|4-4}}After Winker.<ref name=ch04r114>Winker, C., D., 1982, Cenozoic shelf margins, northwestern Gulf of mexico: Gulf Coast Assoc. of Geological Societies Transactions, vol. 32, p. 427–448.</ref> Copyright: Gulf Coast Association of Geological Societies.]]
===GOM depocenter summary===
In the case of the northern Gulf of Mexico, the depocenters prograde over the transitional crust and deform the underlying salt, forming a complex network of salt-cored anticlines and salt-withdrawal synclines. Between 2.5 and 2.0 Ma, the major northern Gulf of Mexico depocenter was focused offshore western Louisiana and eastern Texas. The westernmost part of this depocenter area, the High Island–East Breaks depocenter, appears to have been the input area for the ancestral Mississippi River system. The resulting depocenter has more than [[depth::16,000 ft]] (4875 m) of late Pliocene and early Pleistocene sediments deposited during a succession of high-amplitude sea level cycles (see section C, Depositional Sequences).
==See also==
* [[Depocenters]]
* [[Mapping and analysis of depocenters]]
* [[Example: mapping fluvial input]]
==References==
{{reflist}}
==External links==
{{search}}
* [http://archives.datapages.com/data/specpubs/beaumont/ch04/ch04.htm Original content in Datapages]
* [http://store.aapg.org/detail.aspx?id=545 Find the book in the AAPG Store]
[[Category:Critical elements of the petroleum system]]
[[Category:Sedimentary basin analysis]]
| image = exploring-for-oil-and-gas-traps.png
| width = 120px
| series = Treatise in Petroleum Geology
| title = Exploring for Oil and Gas Traps
| part = Critical elements of the petroleum system
| chapter = Sedimentary basin analysis
| frompg = 4-1
| topg = 4-123
| author = John M. Armentrout
| link = http://archives.datapages.com/data/specpubs/beaumont/ch04/ch04.htm
| pdf =
| store = http://store.aapg.org/detail.aspx?id=545
| isbn = 0-89181-602-X
}}
Mapping age-specific isopach thicks in the northern GOM basin defines laterally shifting sites of maximum deposition (Figure 4-4). Methods of mapping are clearly presented in Tearpock and Bischke.<ref name=ch04r94>Tearpock, D., J., Bischke, R., E., 1991, Applied Subsurface Geologic Mapping: Prentice-Hall, 648 p.</ref>
==GOM basin depocenter time intervals==
In the northern GOM basin, depocenters prograde (Figure 4-4) over the transitional crust (Figure 4-6) and deform the underlying salt into a complex network of salt-cored anticlines and salt-withdrawal synclines (Figures 4-8, 9). Late Neogene depocenters of the Mississippi River, the largest source of sediment to the northern Gulf of Mexico, developed during five time periods from the latest Miocene through Holocene (from ;<ref name=ch04r75>Piggott, N., Pulham, A., 1993, Sedimentation rate as the control on hydrocarbon sourcing, generation, and [[migration]] in the deepwater Gulf of Mexico: Proceedings, Gulf Coast Section SEPM 14th Annual Research conference, p. 179–191.</ref> see also .<ref name=ch04r38>Goldthwaite, D., 1991, Central Gulf Coast stratigraphy, in Goldthwaite, D., ed., An Introduction to Central Gulf Coast Geology: New Orleans Geological Society, p. 17–30.</ref> Following are the five depocenter intervals and their time periods.
{| class = "wikitable"
|-
! Interval
! Time period, ma
|-
| A
| 6–4
|-
| B
| 4–3
|-
| C
| 3–2.5
|-
| D
| 2.5–1
|-
| E
| 1–Present
|}
Figures 4-13 to 4-16 are maps of depocenters and paleogeography for intervals A, B, D, and E. These were constructed by correlating wells using fossil extinction events and grids of interpreted seismic reflection profiles. The High Island–East Breaks study area is shown on each map.
[[file:sedimentary-basin-analysis_fig4-13.png|thumb|{{figure number|4-13}}After Piggott and Pulham<ref name=ch04r75 />). Copyright: Gulf Coast Section SEPM.]]
[[file:sedimentary-basin-analysis_fig4-14.png|thumb|{{figure number|4-14}}After Piggott and Pulham<ref name=ch04r75 />). Copyright: Gulf Coast Section SEPM.]]
[[file:sedimentary-basin-analysis_fig4-15.png|thumb|{{figure number|4-15}}After Piggott and Pulham<ref name=ch04r75 />). Copyright: Gulf Coast Section SEPM.]]
[[file:sedimentary-basin-analysis_fig4-16.png|thumb|{{figure number|4-16}}After Piggott and Pulham<ref name=ch04r75 />).]]
==Formation of high island-east breaks depocenter==
Between 2.5 and 2.0 Ma, the major northern GOM basin depocenter was focused offshore of western Louisiana and eastern Texas. The westernmost part of this depocenter appears to have been the input area for the ancestral Mississippi River system. The resulting depocenter, the High Island–East Breaks depocenter, has more than [[depth::16,000 ft]] (4875 m) of late Pliocene and early Pleistocene sediments deposited during a succession of highamplitude sea level cycles.
==Timing of petroleum generation==
Each of the isopach maps in this section is annotated with the area of active petroleum generation and migration. These comments are based on the [[modeling]] of Piggott and Pulham<ref name=ch04r75 />), illustrated and discussed along with Figures 4-32 and 4-33.
[[file:sedimentary-basin-analysis_fig4-32.png|thumb|{{figure number|4-32}}After Piggott and Pulham<ref name=ch04r75 />). Copyright: Gulf Coast SEPM.]]
[[file:sedimentary-basin-analysis_fig4-33.png|thumb|{{figure number|4-33}}After Piggott and Pulham<ref name=ch04r75 />). Copyright: Gulf Coast SEPM.]]
==Interval A paleogeography==
The figure below shows the paleogeography of the Mississippi River depositional system from approximately 6 Ma to 4 Ma (interval A). Deposition consists of net sand isopach thicks on the shelf and intraslope basins that are interpreted to be deepwater “fan” complexes.
==Interval B paleogeography==
This figure shows paleogeography from approximately 4 Ma to 3 Ma (interval B). Shelf and intraslope basin thicks are potentially sand prone. (Note the shift westward from the previous depocenter location.)
==Interval D paleogeography==
The following figure shows paleogeography from approximately 2.5 Ma to 2 Ma (interval D). Again, shelfal net sand thicks and intraslope basin isopach thicks interpreted to be deepwater “Tan” complexes are the dominant depositional environments. Note the depocenter has shifted to offshore western Louisiana and Texas. The High Island-East Breaks study area occurs within the western part of this depocenter.
==Interval E paleogeography==
The paleogeographic map below represents time from about 1 Ma to the present (interval E). Canyons are interpreted from incised and back-filled geometries on seismic reflection profiles. Note the depocenter has shifted back to offshore eastern Louisiana from the preceding location offshore eastern Texas/western Louisiana.
==Depocenter summary==
Mapping age-specific isopach thicks defines laterally shifting sites of maximum deposition along the margin of the basin. Each of these depocenters has a unique history of accumulation with consequent variations in [[maturation]], migration, and entrapment histories. Evaluation of depocenter maps should include comparison of the results with the largerscale isopach maps (Figures 4-3, 4-4).
[[file:sedimentary-basin-analysis_fig4-3.png|thumb|{{figure number|4-3}}.]]
[[file:sedimentary-basin-analysis_fig4-4.png|thumb|{{figure number|4-4}}After Winker.<ref name=ch04r114>Winker, C., D., 1982, Cenozoic shelf margins, northwestern Gulf of mexico: Gulf Coast Assoc. of Geological Societies Transactions, vol. 32, p. 427–448.</ref> Copyright: Gulf Coast Association of Geological Societies.]]
===GOM depocenter summary===
In the case of the northern Gulf of Mexico, the depocenters prograde over the transitional crust and deform the underlying salt, forming a complex network of salt-cored anticlines and salt-withdrawal synclines. Between 2.5 and 2.0 Ma, the major northern Gulf of Mexico depocenter was focused offshore western Louisiana and eastern Texas. The westernmost part of this depocenter area, the High Island–East Breaks depocenter, appears to have been the input area for the ancestral Mississippi River system. The resulting depocenter has more than [[depth::16,000 ft]] (4875 m) of late Pliocene and early Pleistocene sediments deposited during a succession of high-amplitude sea level cycles (see section C, Depositional Sequences).
==See also==
* [[Depocenters]]
* [[Mapping and analysis of depocenters]]
* [[Example: mapping fluvial input]]
==References==
{{reflist}}
==External links==
{{search}}
* [http://archives.datapages.com/data/specpubs/beaumont/ch04/ch04.htm Original content in Datapages]
* [http://store.aapg.org/detail.aspx?id=545 Find the book in the AAPG Store]
[[Category:Critical elements of the petroleum system]]
[[Category:Sedimentary basin analysis]]