New global marine gravity model from CryoSat-2 and Jason-1 reveals buried tectonic structure

The idea of a simple linear boundary between continental and oceanic crust at extended continental margins is widely recognised to be an oversimplification. Despite this, such boundaries continue to be mapped because of their perceived utility in palinspastic and plate kinematic reconstructions. To examine whether this perception is justified, we review the data and models on which basis continent ocean boundaries are interpreted, and map a set of such interpretations worldwide from more than 150 publications. The maps show that the location of the continent ocean boundary is rarely consistently estimated within the ~10-100 km observational uncertainty that might be expected of the geophysical data used for doing so, that this is the case regardless of whether the transition zone behind the boundary is classified as magma rich or magma poor, and that the geographical separation of estimates exceeds the width of single-study continent ocean transition zones. The average of global maximum separations across sets of three or more estimates is large (167 km) and mostly a consequence of interpretations published over the last decade. We interpret this to indicate an extra component of uncertainty that is related to authors' understanding of the range of features that are interpretable at extended continental margins. We go on to discuss the implications of this uncertainty for palinspastic and plate kinematic modelling using examples from the literature and from the South Atlantic ocean.We conclude that a precise continent ocean boundary concept with locational uncertainty defined from the ensembles is of limited value for palinspastic reconstructions because the reconstruction process tends to bunch the ensemble within a region that is (i) of similar width to the observational uncertainties associated with continent ocean boundary estimates, (ii) narrower than the regions of uncertainty about rotated features implied by the propagation of uncertainties from plate rotation parameters, and (iii) coincident, within all the above uncertainties, with the more-easily mapped continental shelf gravity anomaly.Secondly, we conclude that estimated continent ocean boundaries are of limited use in developing or testing plate kinematic reconstructions because (i) reconstructions built using them as markers do not, within uncertainty limits defined from the ensembles, differ greatly from those using more-easily determined bathymetric or gravity anomaly contours, and (ii) because it is impossible to segment and date them with useful precision to use as markers of the edges of rigid oceanic lithosphere outside of the constraints of a pre-existing plate kinematic model.

show abstract

“…Background shows the shelfrelated free-air gravity anomaly (Sandwell et al, 2014), to which the restored COB ensemble is a close match. …”

Section: Resultsmentioning

confidence: 99%

Getting over continent ocean boundaries

Eagles

Pérez-Díaz

Scarselli

2015

Earth-Science Reviews

View full text Add to dashboard Cite

show abstract

“…The gravity map shown in Figure 4 was compiled using a gravity database that included data from Sandwell et al [31] for offshore regions and an Earth Gravitational Model (EGM2008) for terrestrial regions. The RMS error of the associated accuracy of EGM2008 is approximately ±1 mGal.…”

Section: Gravitymentioning

confidence: 99%

Study of Subsidence and Earthquake Swarms in the Western Pakistan

et al. 2016

View full text Add to dashboard Cite

“…Heads is correct in pointing out that the mapping of seamounts is far from complete (Kim and Wessel 2011;Sandwell et al 2014), and many researchers studying the history of island biotas would no doubt be excited at the prospect of obtaining accurate maps of seamounts, and, especially, knowledge of when some of these were islands. But it is a major leap from the reasonable assumption that many such islands existed to the extreme conclusion that such former lands housed metapopulations from which all or nearly all native lineages of the Hawaiian archipelago are derived by normal dispersal, especially given the apparently young ages of most taxa on these islands.…”

Section: The Hawaiian Islandsmentioning

confidence: 99%

Jurassic primates, immobile ducks and other oddities: a reply to Heads’ review of The Monkey’s Voyage

Queiroz

2016

Aust. Systematic Bot.

View full text Add to dashboard Cite

Abstract. In The Monkey's Voyage, I focused on the issue of disjunct distributions, and, in particular, on the burgeoning support from molecular-dating studies for long-distance dispersal over vicariance as the most reasonable explanation for many (but by no means all) distributions broken up by oceans. Michael Heads' assessment of the book is founded on his long-standing belief, following Croizat, that long-distance dispersal is an insignificant process and, therefore, that disjunctions are virtually always attributable to vicariance. In holding to these notions, Heads offered a series of unsound arguments. In particular, to preserve an 'all-vicariance' perspective, he presented a distorted view of the nature of long-distance dispersal, misrepresented current applications of fossil calibrations in molecular-dating studies, ignored methodological biases in such studies that often favour vicariance hypotheses, repeatedly invoked irrelevant geological reconstructions, and, most strikingly, showed a cavalier approach to evolutionary timelines by pushing the origins of many groups back to unreasonably ancient ages. The result was a succession of implausible histories for particular taxa and areas, including the notions that the Hawaiian biota is almost entirely derived from ancient (often Mesozoic) central Pacific metapopulations, that the disjunctions of extremely mobile organisms such as ducks rarely, if ever, result from long-distance dispersal, and that primates were widespread 120 million years before their first appearance in the fossil record. In contrast to Heads' perspective, a central message of The Monkey's Voyage is that explanations for disjunct distributions should be evaluated on the basis of diverse kinds of evidence, without strong a priori assumptions about the relative likelihoods of long-distance dispersal and vicariance.

show abstract

New global marine gravity model from CryoSat-2 and Jason-1 reveals buried tectonic structure

Cited by 1,164 publications

References 31 publications

Getting over continent ocean boundaries

Getting over continent ocean boundaries

Study of Subsidence and Earthquake Swarms in the Western Pakistan

Jurassic primates, immobile ducks and other oddities: a reply to Heads’ review of The Monkey’s Voyage

Contact Info

Product

Resources

About