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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: A Chronology of Paleozoic Sea-Level Changes
Director for Marine Geosciences Programs
at National Science Foundation (NSF)
Aglobal synthesis of Paleozoic sequence-stratigraphic data has led to new insights into the nature, amplitude, and causes of base-level changes for this era. A “modal mean” Paleozoic sealevel curve is proposed based on “reference districts” from around the world, corroborated with data from ancillary sections. Estimating the amplitude of sea-level changes in the Paleozoic involves two separate measures: 1) long-term envelope of the sealevel changes driven by long-term tectonic processes, and 2) shorter-term third- and higher-order eustatic sealevel changes driven by glacial and other, unknown, processes that can be widely documented.
For the long-term envelope, a consideration
of the global continental flooding
estimates with epeirogenic corrections,
stacked regional sea-level data, and
modeling results for mean age of the
oceanic crust seem to yield consistent
results. For the shorter-term eustatic
changes, sea-level rise and fall estimates
from “reference districts” for various
time
slices
is considered the best
approach. Reference districts are localities
where tectonic quiescence prevailed
and thus the “modal mean” signal is
more likely to be preserved.
Nevertheless, accurate estimates of the magnitude of sea-level changes from
Cambrian-Ordovician
sea-level changes. The
time
scale and standard and regional stages are modeled.
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stratigraphy remain a challenge. As for the causes of short-term
sea-level changes, nearly 38% of the Paleozoic experienced some
or significant glaciation and thus a glacio-eustatic cause can be
invoked for those intervals. For the remaining time
, when there is
no known evidence of ice accumulation, the trigger for sea-level
changes is as yet unknown and remains one of the major mysteries
of the earth sciences.
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