『Abstract
The growing interest in quantification of vertical ground motion
stems from the need to understand in detail how the Earth's crust
behaves, for both scientific and social reasons. However, only
recently has the refinement of dating techniques made possible
the use of paleoshorelines as reliable tools for tectonic studies.
Although there are many local studies of Quaternary vertical motions
of coastlines, we know of no comprehensive worldwide synthesis.
Here provide a compilation of 890 records of paleoshoreline sequences,
with particular emphasis on the last interglacial stage (Marine
Isotopic Stage [MIS] 5e, 〜122 ka). The quality of dating MIS 5e
makes it a reliable marker to evaluate vertical ground motion
rates during the late Quaternary on a global scale. The results
show that most coastal segments have risen relative to sea-level
with a mean uplift rate higher than 0.2 mm/yr, i.e. more than
four times faster than the estimated eustatic drop in sea level.
The results also reveal that the uplift rate is faster on average
for active margins than for passive margins. Neither dynamic topography
nor glacio-hydro-isostasy may explain sustained uplift of all
continental margins, as revealed by the wide distribution of uplifted
sequences of paleoshorelines. Instead, we suggest that long-term
continental accretion has led to compression of continental plates
and uplift of their margins. Therefore this study concludes that
plate-tectonics processes impact all margins and emphasizes the
fact that the notion of a stable platform is unrealistic. These
results therefore seriously challenge the evaluation of past sea
levels from the fossil shoreline record.
Keywords: Sequences of paleo-shorelines; Last interglacial stage;
MIS 5e; Sea-level; Quaternary; Plate tectonics
Contents
1. Introduction
2. Paleo-shorelines of the last interglacial stage
2.1. Marine Isotopic Substage 5e (KIS 5e)
2.2. Paleo-shorelines
3. Methods
3.1. Database
3.2. Uplift rates
4. Results
4.1. Occurrence of morphologies
4.2. Uplift since MIS 5e
5. Discussion
5.1. Morphological classification of Quaternary coastal sequences
5.2. Origin of observed uplift
(1) Eustasy
(2) Glacio-hydro-isostasy
(3) Dynamic topography
(4) Plate tectonics
6. Conclusions
Acknowledgments
Appendix A. Supplementary data
References