Inverted barometer contributions to recent sea level changes along the northeast coast of North America

2015 ◽  
Vol 42 (14) ◽  
pp. 5918-5925 ◽  
Author(s):  
Christopher G. Piecuch ◽  
Rui M. Ponte
1992 ◽  
Vol 6 ◽  
pp. 149-149
Author(s):  
Jisuo Jin

Three rhynchonellid brachiopod genera, Hiscobeccus, Lepidocyclus, and Hypsiptycha, are the most diagnostic elements of the Lepidocyclus fauna of North America in Late Ordovician time. These are characterized by relatively large, strongly biconvex to globular shells with coarse imbricating growth lamellae and, internally, with septiform cardinal processes in brachial valves. Among the three genera, Hiscobeccus appears the earliest, now known from rocks of late Trentonian-Edenian age in the Canadian Rocky Mountains and Mackenzie Mountains. Morphologically, Hiscobeccus is distinguished from the other two genera by its open delthyrium in the pedicle valve. Early forms of Hiscobeccus show close morphological similarity to Rhynchotrema in their non-globular biconvex shells covered by strong growth lamellae only in the anterior portions. It has been suggested that Hiscobeccus evolved from the Rhynchotrema wisconsinense stock through increase in shell size, globosity, and strength of growth lamellae. Earliest species of Rhynchotrema has been documented convincingly from rocks of early Trentonian age, and the derivation of Hiscobeccus most likely took place during the mid-Trentonian. Lepidocyclus and Hypsiptycha evolved from either Rhynchotrema or Hiscobeccus by developing a pair of deltidial plates covering the delthyrium.Rhynchotrema and other rhynchonellids that evolved before mid-Trentonian time are common to the North American (Laurentian) and the Siberia-Kazakhstan paleocontinents. In contrast, Hiscobeccus, Lepidocyclus, and Hypsiptycha that evolved after the mid-Trentonian are virtually restricted to Laurentia. Therefore, Rhynchotrema marked the last successful intercontinental migration of rhynchonellids during their Llandeilian-Caradocian cosmopolitanism. The pronounced provincialism of the North American Lepidocyclus fauna may have been caused by a number of factors. Facies control is not likely the explanation because these rhynchonellids occur in nearly all the inland and marginal platform seas of Laurentia and commonly are found together in the same types of rocks. Plate tectonics and sea-level changes are considered major causes. The Ordovician rhynchonellids lived in shallow marine (intertidal-subtidal) environments and were incapable of crossing vast, deep oceanic barriers because of their sedentary mode of life and short-lived motile larval stages. The widening of the ocean between North America and Siberia, coupled with high sea-level stand, may have created a sufficiently wide oceanic barrier to interrupt faunal mixing between the two paleocontinents by late Trentonian time. Moreover, the rise in sea level would have resulted in the disappearance of island faunas, which could have served as stepping stones for intercontinental migration of shallow-water benthic faunas during low sea-level stand.


1993 ◽  
Vol 130 (4) ◽  
pp. 443-452 ◽  
Author(s):  
R. L. Ripperdan ◽  
M. Magaritz ◽  
J. L. Kirschvink

AbstractCarbon isotope and magnetic polarity stratigraphic results from the Cambrian-Ordovician Boundary section at Xiaoyangqiao, near Dayangcha, Jilin Province, China, in comparison to a contemporaneous section at Black Mountain, Australia, indicate strata equivalent to major portions of the Australian sequence are either absent or are restricted to highly condensed intervals. These intervals are correlative with regressive sea level events identified in Australia and western North America, suggesting regional or eustatic sea level changes strongly influenced deposition of the Xiaoyangqiao sequence. These results also suggest the Xiaoyangqiao section is unfavourable as the site of the Cambrian-Ordovician Boundary Global Stratotype Section and Point.


2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Paul B. Goddard ◽  
Jianjun Yin ◽  
Stephen M. Griffies ◽  
Shaoqing Zhang

Paleobiology ◽  
1996 ◽  
Vol 22 (1) ◽  
pp. 66-79 ◽  
Author(s):  
Bruce S. Lieberman ◽  
Niles Eldredge

Phylogenetic patterns of trilobite clades were used to deduce biogeographic patterns during the Middle Devonian, a time of active plate collision between North America (Laurentia) and other plates, coincident with several major episodes of sea-level rise and fall. The mapping of biogeographic states onto phylogenies for asteropyginid and proetid trilobites indicated that during their history these trilobite clades often shifted the areas they occupied, and also underwent vicariant differentiation, followed by range expansion, followed by subsequent vicariance. Biogeographic patterns in these individual phylogenies were evaluated and synthesized using a modified version of Brooks Parsimony Analysis, which is discussed. This method makes it possible using cladistic methods to distinguish between episodes of vicariance and episodes of dispersal. Two types of dispersal are recognized herein: (1) the individualistic responses of certain taxa in a single clade that cannot be generalized, i.e., traditional ad hoc dispersal, and (2) those patterns of congruent range expansion that are replicated across several clades. The latter are not treated as true dispersal, expansion of a taxon's range over a barrier accompanied by diversification, but rather as a result of the temporary removal of barriers to marine taxa, due either to relative sea-level rise or to the collision of formerly disjunct plates. These are interpreted as changes in the structure of areas, and this type of dispersal is referred to as geo-dispersal. Geo-dispersal was found to have occurred in the Middle Devonian trilobite fauna of Eastern North America.Biogeographic analysis indicated that Eastern North America is a strongly supported area, with the Appalachian and Michigan Basins as sister areas. Armorica and the Canadian Arctic are also sister areas. Congruence was found between area cladograms produced by vicariance and dispersal analyses for Middle Devonian trilobites, suggesting that in some cases the geological processes governing vicariance, such as sea-level changes, were the same as those that caused dispersal.


2021 ◽  
Author(s):  
Samuel Diabaté ◽  
Didier Swingedouw ◽  
Joël Hirschi ◽  
Aurélie Duchez ◽  
Philip Leadbitter ◽  
...  

<p>The sea level changes along the Atlantic coast of the US have received a lot of attention recently because of an increased rate of rise north of the Gulf Stream separation point since the late 1980s (Sallenger et al., 2012 ; Boon, 2012). While sea-level rise is a major issue for coastal community, sea-level measurements in the region are key to understand the past of the nearby Gulf Stream and the large-scale ocean dynamics. Tide gauges on the coastline have measured the inshore sea-level for many decades and provide a unique window on past oceanic circulation. So far, numerous studies have linked the interannual to multi-decadal coastal sea-level changes to ocean dynamics, including the Gulf Stream strength, the divergence of the Sverdrup transport in the basin interior and the Atlantic meridional overturning circulation. However, other studies argue that local and regional processes, such as the alongshore winds or the river discharges, are processes of greater importance to the coastal sea level.</p><p>The general picture in the Atlantic is hence unclear. Yet, the northwest Atlantic is not the only western boundary region where sea-level has been well sampled. In this study we extend the analysis to the northwest Pacific, where links between the state of the Kuroshio and sea-level are evident (Kawabe, 2005; Sasaki et al., 2014). We discuss similarities and dissimilarities between the western boundary regions. We show for each basin, that the inshore sea level upstream the separation points is in sustained agreement with the meridional shifts of the western boundary current extension. This indicates that long duration tide gauges, such as Fernandina Beach (US) and Hosojima (Japan) could be used as proxies for the Gulf Stream North Wall and the Kuroshio Extension state, respectively.</p><p><strong>References:</strong></p><p>Boon, J. D. (2012). Evidence of sea level acceleration at US and Canadian tide stations, Atlantic Coast, North America. Journal of Coastal Research, 28(6), 1437-1445.<strong> </strong></p><p>Kawabe, M. (2005). Variations of the Kuroshio in the southern region of Japan: Conditions for large meander of the Kuroshio. Journal of oceanography, 61(3), 529-537.</p><p>Sallenger, A. H., Doran, K. S., & Howd, P. A. (2012). Hotspot of accelerated sea-level rise on the Atlantic coast of North America. Nature Climate Change, 2(12), 884-888.</p><p>Sasaki, Y. N., Minobe, S., & Miura, Y. (2014). Decadal sea‐level variability along the coast of Japan in response to ocean circulation changes. Journal of Geophysical Research: Oceans, 119(1), 266-275.</p>


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