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Are Milankovitch cycles 4th or 5th order? And what of sequences that are not specifically or completely related to eustatic sea level change?
Certainly, when there is glaciation (ice house), Milankovitch cycles do affect short-time scale eustasy sea level cycles; but, in the 1st order hot houses, rhythmic facies changes and rhythmic faunal discontinuities never-the-less occur and those in the Cretaceous at least have recently been shown to have correlation with Milankovitch cycles in the absence of changes in glaciation (perhaps only influencing wide changes in precipitation and aquifer storage). The prior interpretation of Western Interior Seaway cyclicity has naturally assumed sea-level change or tectonic shoreline displacement, but climatic zone shifts can also account for facies and species changes without significant sea-level change. In other words, is the Stratigraphic cycle concept exclusive to sea-level changes? If Sequence Stratigraphy is exclusive to marine-terrestrial cycles, then I can understand the restriction to sea-level change, in which case Milankovitch cycles only conditionally influence cyclic eustatic sea level change, but otherwise generally influence cyclic sedimentation change.
IveGoneAway ( talk) 14:28, 6 May 2021 (UTC) IveGoneAway ( talk) 15:11, 6 May 2021 (UTC)
Type | Other Terms | Duration (in millions of years) |
---|---|---|
Fifth-order | 6-10 | |
Sixth-order | 1-3 | |
Seventh-order | 0.4-0.5 |
I get it that geologists may speak of "transgression events" and "regression events" and may even speak of an individual stratigraphic cycle as an "event", but such stratigraphic cycle events often have durations on the order of millions of years, and that very fact prevents rock dating to high precision, resulting in inconsistencies and errors in identifying rocks and fossils. So, discussions of such long events do not seem to address the primary scientific values of the sorts of events as "... large storm, landslide, volcanic eruption, or flood ... ash falls [especially], lava flows, lahars, and glacial ice-dam breaks; ...", which may have durations ranging from months to minutes.
I could see this section further developed to address these finer scales and even split.
IveGoneAway ( talk) 19:26, 12 September 2021 (UTC)
![]() | This article is rated Start-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | ||||||||||
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Are Milankovitch cycles 4th or 5th order? And what of sequences that are not specifically or completely related to eustatic sea level change?
Certainly, when there is glaciation (ice house), Milankovitch cycles do affect short-time scale eustasy sea level cycles; but, in the 1st order hot houses, rhythmic facies changes and rhythmic faunal discontinuities never-the-less occur and those in the Cretaceous at least have recently been shown to have correlation with Milankovitch cycles in the absence of changes in glaciation (perhaps only influencing wide changes in precipitation and aquifer storage). The prior interpretation of Western Interior Seaway cyclicity has naturally assumed sea-level change or tectonic shoreline displacement, but climatic zone shifts can also account for facies and species changes without significant sea-level change. In other words, is the Stratigraphic cycle concept exclusive to sea-level changes? If Sequence Stratigraphy is exclusive to marine-terrestrial cycles, then I can understand the restriction to sea-level change, in which case Milankovitch cycles only conditionally influence cyclic eustatic sea level change, but otherwise generally influence cyclic sedimentation change.
IveGoneAway ( talk) 14:28, 6 May 2021 (UTC) IveGoneAway ( talk) 15:11, 6 May 2021 (UTC)
Type | Other Terms | Duration (in millions of years) |
---|---|---|
Fifth-order | 6-10 | |
Sixth-order | 1-3 | |
Seventh-order | 0.4-0.5 |
I get it that geologists may speak of "transgression events" and "regression events" and may even speak of an individual stratigraphic cycle as an "event", but such stratigraphic cycle events often have durations on the order of millions of years, and that very fact prevents rock dating to high precision, resulting in inconsistencies and errors in identifying rocks and fossils. So, discussions of such long events do not seem to address the primary scientific values of the sorts of events as "... large storm, landslide, volcanic eruption, or flood ... ash falls [especially], lava flows, lahars, and glacial ice-dam breaks; ...", which may have durations ranging from months to minutes.
I could see this section further developed to address these finer scales and even split.
IveGoneAway ( talk) 19:26, 12 September 2021 (UTC)