Volcanic contribution to emergence of Central Panama in the Early Miocene

David M Buchs,Roberto Miranda,Stewart D Redwood,Henry Coombs,Eric Chichaco,Mauricio Lacerda,Creed Goff,Rodrigo Arrocha,Pastora Franceschi,Derek Irving,Maurylis Coronado,Eladio Almengor,Enier Portugal,Jian Wang

doi:10.1038/s41598-018-37790-2

Abstract

Formation of the Panama Isthmus, that had global oceanographic and biotic effects in the Neogene, is generally associated with tectonic uplift during collision of the Panama volcanic arc with South America. However, new field, geochemical and geochronological data from the Culebra Cut of the Panama Canal suggest that volcanism also contributed to the Isthmus emergence in the Early Miocene. This volcanism is recorded in a newly-recognised Central Panama volcanic field that includes several phases of development. Early activity of this field along the Panama Canal was associated with proximal effusive to explosive felsic products during formation of subaerial stratovolcanoes and possible domes ca. 21 Ma. This was followed by a period of marine transgression ca. 21–18 Ma, with more distal volcanism documented by tuffs that deposited in marine to terrestrial environments. Finally, proximal mafic volcanism formed tephra cones in a monogenetic field ca. 18(-?) Ma. This was associated with phreatomagmatic processes in a coastal environment, with remarkable kilometre-wide subvolcanic peperitic intrusions. We propose based on these observations that formation of the Central Panama volcanic field was critical in shaping regional topography, and that this could have actively contributed to obstruction and closure of an interoceanic strait in Central Panama.

Highlights

Formation of the Panama Isthmus is a significant geological event that is generally considered to have triggered global oceanic/climatic changes and inter-American migration of terrestrial organisms during the Great American Biotic Interchange (GABI) ca. 3 million years (Ma) ago[1,2,3,4,5]
Geophysical constraints, palaeomagnetic data, and field observations show that the unique topography of Central Panama is at least in part controlled by a complex fault network associated with crustal-scale dismemberment of transisthmian volcanic cordilleras since the Late Eocene[26,27,28,29,30,31,32]
Different segments of the Panama volcanic arc have been affected by complex, diachronous uplift events due to local and regional tectonic processes that are not related to collision with South America[10,12,28,55,56]

Summary

Introduction

Formation of the Panama Isthmus is a significant geological event that is generally considered to have triggered global oceanic/climatic changes and inter-American migration of terrestrial organisms during the Great American Biotic Interchange (GABI) ca. 3 million years (Ma) ago[1,2,3,4,5]. Along the Gaillard (or “Culebra”) Cut of the Panama Canal (southern Central Panama, Figs 2 and 3), this Late Eocene transgression was followed by deposition of sediments and volcanic/volcaniclastic products in: (i) a terrestrial environment (Bas Obispo and Las Cascadas Formations, Oligocene to Early Miocene); (ii) shallow-marine to bathyal environments (Culebra Formation, Early Miocene); and (iii) a terrestrial environment (Cucaracha and Pedro Miguel Formations, Early Miocene)[13,17,26,37,38,40,41]. The geological record in Central Panama preserves at least 3 main cycles of marine transgression and regression since the Late Eocene Relationships between these cycles and volcanic and tectonic processes remain poorly constrained. The volcanic evolution of this area and its possible links to the emergence of Central Panama remain to be characterised in detail

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