Tectonic terranes of the Chortis block based on integration of regional aeromagnetic and geologic data

Abstract

An aeromagnetic survey of Honduras and its northeastern Caribbean coastal area covering a continuous area of 137,400 km 2 was acquired by the Honduran government in 1985 and provided to the University of Texas at Austin for research purposes in 2002. We correlate regional and continuous aeromagnetic features with a compilation of geologic data to reveal the extent, structural grain, and inferred boundaries of tectonic terranes that compose the remote and understudied, Precambrian-Paleozoic continental Chortis block of Honduras. A regional geologic map and a compilation of isotopic age dates and lead isotope data are used in conjunction with and geo-referenced to the aeromagnetic map, which provide a basis for subdividing the 531,370 km 2 Chortis block into three tectonic terranes with distinctive aeromagnetic expression, lithologies, structural styles, metamorphic grade, isotopically and paleontologically-determined ages, and lead isotope values: (1) the Central Chortis terrane occupies an area of 110,600 km 2 , exhibits a belt of roughly east-west-trending high magnetic values, and exposes small, discontinuous outcrops of Grenville to Paleozoic continental metamorphic rocks including greenschist to amphibolite grade phyllite, schist, gneiss, and orthogneiss that have been previously dated in the range of 1 Ga to 222 Ma; the northern 59,990 km 2 margin of the Central Chortis terrane along the northern Caribbean coast of Honduras exhibits an irregular pattern of east-west-trending magnetic highs and lows that correlates with an east-west-trending belt of early Paleozoic to Tertiary age metamorphic rocks intruded by Late Cretaceous and early Cenozoic plutons in the range of 93.3-28.9 Ma; (2) the Eastern Chortis terrane occupies an area of 185,560 km 2 , exhibits belts of roughly northeast-trending high magnetic values, and correlates with outcrops of folded and thrusted Jurassic metasedimentary phyllites and schists forming a greenschist-grade basement; we propose that the Eastern and Central terranes are distinct terranes based on the strong differences in their structural style Rogers, R.D., Mann, P., Emmet, P.A., 2007, Tectonic terranes of the Chortis block based on integration of regional aeromagnetic and geologic data, in Mann, P., ed.,

A 3-D shear velocity model of the southern North American and Caribbean plates from ambient noise and earthquake tomography

“…9d). This seismological lower crustal difference agrees with the different origin and tectonic evolution proposed by several studies from geologic evidence and paleotectonic reconstructions (e.g., Burke, 1988;Rogers et al, 2007;Pindell and Kennan, 2009). It also reveals crustal heterogeneity on the Caribbean plate oceanic basins (Colombia, Venezuela, and Grenada) (Fig.…”

Tectonic evolution of the Gulf of Mexico, Caribbean and northern South America in the mantle reference frame: an update

“…This complexity, along with an apparent lack of disruption in gravity data and seismic lines in the Gulf of Tehuantepec, led Keppie & Morán-Zenteno (2005) to question the commonly inferred westward trace of the Motagua Fault toward the Middle America Trench, and hence to doubt whether Chortís and Mexico had been adjacent in the Cretaceous, despite the lithological similarities between Chortís and the Oaxaca and Mixteca terranes of Mexico (e.g. Rogers et al 2007b). These authors position Chortís out in the Pacific away from Mexico, employing faults visible on seismic at about 14.38N in the offshore forearc as a means of deriving Chortís from the WSW.…”

Kinematic reconstruction of the Caribbean region since the Early Jurassic

“…Oceanic extensional records Atlantic; Cayman Trough Torsvik et al (2012); Leroy et al (2000) Transform and strike-slip records Motagua; Cuba; Andes Burkart (1983Burkart ( , 1994; Rosencrantz (1990), Cruz-Orosa et al (2012a); Kerr et al (1998) Venable (1994), Rogers et al (2007); Pindell and Kennan (2009), Ratschbacher et al (2009, Solari et al (2013); Meyerhoff and Hatten (1968), Knipper and Cabrera (1974), Pardo (1975), Iturralde-Vinent et al (2008); e.g. Kennan and Pindell (2009) Stearns et al (1982); Burmester et al (1996); Reid et al (1991) before collision of the Caribbean plate, overlying arc and accreted Caribeana fragments with North America (García-Casco et al, 2008a;Iturralde-Vinent et al, 2008;van Hinsbergen et al, 2009).…”