Exhumation of the Panama basement complex and basins: Implications for the closure of the Central American seaway

Abstract

The emergence of the Central American isthmus occurred episodically from Eocene to Pliocene time and was caused by a series of tectonic and volcanic processes. Results from zircon U‐Pb geochronology, zircon (U‐Th)/He (ZHe) and apatite (U‐Th)/He (AHe) thermochronology, and zircon Lu‐Hf isotopic data from sedimentary (sandstones and recent river sands) and plutonic rocks from the Azuero Peninsula and Central Panama document the exhumation and uplift history of the Panamanian basement complex. Our data support previous paleobotanical and thermochronological studies that suggest that by middle Eocene time some areas of Central Panama and Azuero Peninsula were exposed above sea level as a series of islands surrounded by shallow open marine waters. The Gatuncillo, Cobachón and Tonosí formations were deposited during this partial emergence. Transtension in the Oligocene‐early Miocene produced various pull‐apart basins (e.g., the Canal Basin) and local uplift that exhumed the Eocene strata (Gatuncillo and Cobachón formations). This event probably reduced circulation between the Pacific Ocean and the Caribbean Sea. The Tonosí Formation records late Miocene to Pleistocene cooling and exhumation, which may be related to uplift above the subducting Coiba Ridge. These results suggest that the emergence of the Isthmus of Panama followed a series of diachronous events that led to the final closure of the Central American seaway.

From incipient island arc to doubly‐vergent orogen: A review of geodynamic models and sedimentary basin‐fills of southern Central America

“…However, there is an ongoing debate on the timing of the closure of the Isthmus of Panama. Thermochronological data reveal four major cooling events in western and central Panama at 47-42 Ma, 32-28 Ma, 17-9 Ma and 9-0 Ma, which are consistent with the presence of emergent land areas and a reduction of the circulation between the Pacific Ocean and the Caribbean Sea (Ramírez et al, 2016). But the exchange of surface water between the oceans probably stopped much later at 2.…”

Transition From Collisional to Subduction‐Related Regimes: An Example From Neogene Panama‐Nazca‐South America Interactions

“…This has been interpreted as a direct consequence of the tectonic plate readjustments that followed the collision of the leading edge of the CLIP with northwestern South America (Buchs et al, ; Wegner et al, ). By middle Eocene times, this island arc was being constructed at a well‐established subduction zone in which pyroclastic activity and subaerial exposure have been already documented in the Panama area (Montes, Cardona, et al, ; Ramírez et al, ).…”

“…Although this sample passed the chi‐square test ( P ( χ 2 ) = 24%), we interpret these ages as a detrital cooling signal, since no field evidence indicating that this unit reached temperatures above ~70°C were observed and because similar AFT cooling ages have been reported for the potential source domains suggested from the sedimentary provenance analysis, as the Penderisco Fm. (AFT ages around 13–14 Ma), the Panama Arc (AFT ages around 40 Ma) (Montes, Cardona, et al, ; Ramírez et al, ). The above corroborates that the middle to late Miocene sediments of the Atrato Basin, which overly the Panama Arc, were sourced by both the South American‐related and the allochthonous Panamanian terranes.…”

“…Increased tectonic instability during middle Miocene times has been also documented throughout the northwestern Andes and southern Central America from the analysis of the magmatic and deformational record of the region and has been attributed to the collision of the Panama Arc with northwestern South America (Farris et al, , ; Montes, Bayona, et al, ; Ramírez et al, ; Villagómez & Spikings, ) (Farris et al, , ; Montes, Bayona, et al, ; Ramírez et al, ; Spikings et al, ; Villagómez & Spikings, ). Exhumation, increased accumulation rates, and switch from mudstone facies to fluvial conglomeratic facies also document increased instability inboard the continent, in the inter‐Andean Magdalena Valley and Eastern Cordillera (Reyes‐Harker et al, , and references therein).…”

Floral Dissimilarity and the Influence of Climate in the Pliocene High Arctic: Biotic and Abiotic Influences on Five Sites on the Canadian Arctic Archipelago

“…Marincovich (2000) suggested that there were multiple mixing events, with one following the first opening of the Bering Strait (4.8-5.5 Ma), and a second mixing event due to the change of direction of flow through the strait, arguably due to shoaling of the Central American Seaway (∼3.6 Ma; Although see Ramírez et al, 2016). These two periods also coincide with eustatic episodes (Marincovich, 2000).…”