Eocene intra-plate shortening responsible for the rise of a faunal pathway in the northeastern Caribbean realm.

Mélody Philippon,Douwe J J Van Hinsbergen,Fredéric Quillevere,With The Garanti Team ,Marcelle Boudagher-Fadel,Pierre-Olivier Antoine,Philippe Münch,Laurent Marivaux,Lydie Gailler,Lydian M Boschman,Serge Lallemand,Aurelien Gay,Jean-Jacques Cornée,Jean Fredéric Lebrun,Leny Montheil

doi:10.1371/journal.pone.0241000

Abstract

Intriguing latest Eocene land-faunal dispersals between South America and the Greater Antilles (northern Caribbean) has inspired the hypothesis of the GAARlandia (Greater Antilles Aves Ridge) land bridge. This landbridge, however, should have crossed the Caribbean oceanic plate, and the geological evolution of its rise and demise, or its geodynamic forcing, remain unknown. Here we present the results of a land-sea survey from the northeast Caribbean plate, combined with chronostratigraphic data, revealing a regional episode of mid to late Eocene, trench-normal, E-W shortening and crustal thickening by ∼25%. This shortening led to a regional late Eocene-early Oligocene hiatus in the sedimentary record revealing the location of an emerged land (the Greater Antilles-Northern Lesser Antilles, or GrANoLA, landmass), consistent with the GAARlandia hypothesis. Subsequent submergence is explained by combined trench-parallel extension and thermal relaxation following a shift of arc magmatism, expressed by a regional early Miocene transgression. We tentatively link the NE Caribbean intra-plate shortening to a well-known absolute and relative North American and Caribbean plate motion change, which may provide focus for the search of the remaining connection between 'GrANoLA' land and South America, through the Aves Ridge or Lesser Antilles island arc. Our study highlights the how regional geodynamic evolution may have driven paleogeographic change that is still reflected in current biology.

Highlights

Darwin [1] already recognized that the West Indies (Greater Antilles, Bahamas, and Lesser Antilles) appear to have been colonized by South American terrestrial mammal faunas
We evaluate our findings in terms of the occurrence, timing, and style of intra-plate deformation, and estimate whether this may have contributed to the rise and demise of a landmass that would have connected the Greater Antilles to the Aves Ridge
On the Greater Antilles islands to the west, Cenozoic shortening prior to and during the Eocene collision with the Bahamas platform was restricted to accretionary orogenesis, stacking sedimentary units belonging to the subducting North American Plate below the overriding Caribbean lithosphere [12, 44]

Summary

Introduction

Darwin [1] already recognized that the West Indies (Greater Antilles, Bahamas, and Lesser Antilles) appear to have been colonized by South American terrestrial mammal faunas. We evaluate to what extent mid-Eocene changes in plate kinematic setting generated intra-plate deformation that may have contributed to land uplift and emergence in the northern Lesser Antilles islands Most of these islands are Miocene and younger volcanoes, but the northeastern ones, between the active volcanic arc and the trench, expose Eocene volcano-sedimentary rocks [23, 24] that reveal evidence for Caribbean plate deformation [23, 25]. These Eocene–Oligocene volcanic rocks were often formed subaerially, and erosional unconformities have been documented above Paleocene–Eocene marine series affecting the Anguilla and Saba banks [23, 24, 40] This suggests that during and after the Eocene Caribbean plate reorganization, the northeastern Caribbean region underwent vertical motions and emergence, followed by subsidence, which is of interest in evaluating the GAARlandia hypothesis. Previous estimates suggested 15% of Oligocene and younger extension in the northern Lesser Antilles region [23, 38]

Discussion

Conclusion