The Geology of the Darien, Panama, and the late Miocene-Pliocene collision of the Panama arc with northwestern South America

Abstract

The geology of the Darien province of eastern Panama is presented through a new geologic map and detailed biostratigraphic and paleobathymetric analysis of its Upper Cretaceous to upper Miocene sediments. The sequence of events inferred from the stratigraphie record includes the collision of the Panama arc (the southwestern margin of the Caribbean plate) and South American continent. Three tectonostratigraphic units underlie the Darien region: (1) PrecoUisional Upper Cretaceous-Eocene crystalline basement rocks of the San Bias Complex form a series of structurally complex topographic massifs along the northeastern and southwestern margins of the Darien province. These rocks formed part of a >20 m.y. submarine volcanic arc developed in a Pacific setting distant from the continental margin of northwestern South America. The northerly basement rocks are quartz diorites, granodiorites, and basaltic andésites, through dacites to rhyolites, indicating the presence of a magmatic arc. The southerly basement rocks are an accreted suite of diabase, pillow basalt, and radiolarian chert deposited at abyssal depths. PrecoUisional arc-related rocks, of Eocene to lower Miocene age, consist of 4000 m of pillow basalts and volcaniclastics, and biogenic calcareous and siliceous deepwater sediments. They consist of the Eocene-'Present address: 4193, Lower Cove Run Road,

Cenozoic biogeography and evolution in direct-developing frogs of Central America (Leptodactylidae: Eleutherodactylus) as inferred from a phylogenetic analysis of nuclear and mitochondrial genes

“…Trans-oceanic dispersal by amphibians is an unlikely phenomenon (Darwin, 1859), but it does happen (Hedges et al, 1992;Vences et al, 2003Vences et al, , 2004. One advantage of a younger Craugastor, however, is that the southern portion of its biogeographic history would be more easily reconciled with the relatively young age of lower Central America (Coates et al, 2004;Whitmore and Stewart, 1965). Such alternative possibilities highlight our need for more independent rate calibrations for Eleutherodactylus, and for more amphibians in general.…”

“…Second, Syrrhophus is thought to have originated in northern Mesoamerica 40-30 mya through the dispersal from the Greater Antilles by an ancestral member of the Euhyas lineage (Hass and Hedges, 1991;Hedges, 1989). Third, with the gradual formation of a new land bridge (Coates et al, 2004) and the reconnection of Central and South America just prior to 3 mya (Coates and Obando, 1996), species of the subgenus Eleutherodactylus entered lower Central America (Savage, 2002;Vanzolini and Heyer, 1985) and today extend as far north as Honduras (McCranie and Wilson, 2002).…”

History of upwelling in the Tropical Eastern Pacific and the paleogeography of the Isthmus of Panama

“…Pinto-Sanchez et al, 2012) records via rafting helped by the formation of an ephemeral near-complete land bridge around 10 Ma (Roth et al, 2000;Coates et al, 2003;Coates et al, 2004). Likewise, the effects of deeper water shut-off occurred long before those of shallow water as observed in the timings of separation of different organisms with different life histories (O'Dea et al, 2007a;Landau et al, 2009;Smith and Jackson, 2009) and the earlier molecular divergences of deep-water vs. shallow-water organisms (Knowlton and Weigt, 1998;Naro-Maciel et al, 2008).…”

“…We therefore conclude that non-analogous oceanographic conditions existed in the Pliocene TEP. Such conditions are easily envisioned given that the CAS still maintained a connection to the Caribbean in the east in the Atrato Strait (Duque-Caro, 1990;Coates et al, 2004).…”

“…Uplift rates based on paleobathymetries of marine sediments from across the Isthmus suggest that the majority of the volcanic arc was submerged up until very recently with bathyal sediments of latest Miocene age present in the Caribbean and Pacific of western Panama, the Caribbean of central Panama and eastern Panama (Coates et al, 1992;Collins, 1992Collins, , 1993Collins, , 1996Coates, 1999;Coates et al, 2000Coates et al, , 2003Coates et al, , 2004Coates et al, , 2005. Strong similarities between Pacific and Caribbean Mio-Pliocene biota (Chaisson and Ravelo, 2000;O'Dea et al, 2007b) and near-identical environmental conditions on either side of the Isthmus (Keigwin, 1978(Keigwin, , 1982Keller et al, 1989;Haug and Tiedemann, 1998;Haug et al, 2001) in the Early Pliocene imply the CAS was maintained in some form until the mid-Pliocene.…”