The North American–Caribbean Plate Boundary in Mexico–Guatemala–Honduras

The North American–Caribbean Plate boundary in Mexico–Guatemala–Honduras LOTHAR RATSCHBACHER1*, LEANDER FRANZ1, MYO MIN1, RAIK BACHMANN1, UWE MARTENS2, KLAUS STANEK1, KONSTANZE STU¨ BNER1, BRUCE K. NELSON3, UWE HERRMANN3, BODO WEBER4, MARGARITA LO´ PEZ-MARTIŃEZ4, RAYMOND JONCKHEERE1, BLANKA SPERNER1, MARION TICHOMIROWA1, MICHAEL O. MCWILLIAMS2, MARK GORDON5, MARTIN MESCHEDE6 & PETER BOCK1 1Geowissenschaften, Technische Universita¨t Bergakademie Freiberg, 09599 Freiberg, Germany 2Geological and Environmental Sciences, Stanford University, Stanford, CA 94305, USA 3Earth and Space Sciences, University of Washington, Seattle, WA 98195, USA 4CICESE, 22860 Ensenada, B.C., Mexico 5Department of Geology and Geophysics, Rice University, Houston, TX 77251-1892, USA 6Geowissenschaften, Universita¨t Greifswald, 17487 Greifswald, Germany *Corresponding author (e-mail: [email protected]) Abstract: New structural, geochronological, and petrological data highlight which crustal sections of the North American–Caribbean Plate boundary in Guatemala and Honduras accommodated the large-scale sinistral offset. We develop the chronological and kinematic framework for these interactions and test for Palaeozoic to Recent geological correlations among the Maya Block, the Chortı´s Block, and the terranes of southern Mexico and the northern Caribbean. Our principal findings relate to how the North American–Caribbean Plate boundary partitioned deformation; whereas the southern Maya Block and the southern Chortı´s Block record the Late Cretac- eous–Early Cenozoic collision and eastward sinistral translation of the Greater Antilles arc, the northern Chortı´s Block preserves evidence for northward stepping of the plate boundary with the translation of this block to its present position since the Late Eocene. Collision and translation are recorded in the ophiolite and subduction–accretion complex (North El Tambor complex), the continental margin (Rabinal and Chuacu´s complexes), and the Laramide foreland fold–thrust belt of the Maya Block as well as the overriding Greater Antilles arc complex. The Las Ovejas complex of the northern Chortı´s Block contains a significant part of the history of the eastward migration of the Chortı´s Block; it constitutes the southern part of the arc that facilitated the breakaway of the Chortı´s Block from the Xolapa complex of southern Mexico. While the Late Cretaceous collision is spectacularly sinistral transpressional, the Eocene–Recent translation of the Chortı´s Block is by sinistral wrenching with transtensional and transpressional episodes. Our reconstruction of the Late Mesozoic–Cenozoic evolution of the North American–Caribbean Plate boundary identified Proterozoic to Mesozoic connections among the southern Maya Block, the Chortı´s Block, and the terranes of southern Mexico: (i) in the Early–Middle Palaeozoic, the Acatlań complex of the southern Mexican Mixteca terrane, the Rabinal complex of the southern Maya Block, the Chuacu´s complex, and the Chortı´s Block were part of the Taconic–Acadian orogen along the northern margin of South America; (ii) after final amalgamation of Pangaea, an arc developed along its western margin, causing magmatism and regional amphibolite–facies metamorphism in southern Mexico, the Maya Block (including Rabinal complex), the Chuacu´s complex and the Chortı´s Block. The separation of North and South America also rifted the Chortı´s Block from southern Mexico. Rifting ultimately resulted in the formation of the Late Jurassic–Early Cre- taceous oceanic crust of the South El Tambor complex; rifting and spreading terminated before the Hauterivian (c. 135 Ma). Remnants of the southwestern Mexican Guerrero complex, which also rifted from southern Mexico, remain in the Chortı´s Block (Sanarate complex); these complexes share Jurassic metamorphism. The South El Tambor subduction–accretion complex was emplaced onto the Chortı´s Block probably in the late Early Cretaceous and the Chortı´s Block collided with From:JAMES, K. H., LORENTE,M.A.&PINDELL, J. L. (eds) The Origin and Evolution of the Caribbean Plate. Geological Society, London, Special Publications, 328, 219–293. DOI: 10.1144/SP328.11 0305-8719/09/$15.00 # The Geological Society of London 2009. 220 L. RATSCHBACHER ET AL. southern Mexico. Related arc magmatism and high-T/low-P metamorphism (Taxco–Viejo– Xolapa arc) of the Mixteca terrane spans all of southern Mexico. The Chortı´s Block shows continu- ous Early Cretaceous–Recent arc magmatism. Supplementary material: Analytical methods and data, and sample description are available at http://www.geolsoc.org.uk/SUP18360. Structural, geochronological, and petrological data domains (e.g. Dickinson & Lawton 2001; Keppie document the Palaeozoic–Cenozoic pressure– 2004). Most tectonic models suggest that collision temperature–deformation–time (P–T–d–t) his- of the Maya and Chortı´s Blocks occurred along tory of the southern part of the Maya and northern south- or north-dipping subduction zones during part of the Chortı´s Blocks, and the Polochic, the Cretaceous, and caused emplacement of Motagua and Jocotań–Chamelecoń fault zones Jurassic–Cretaceous Proto-Caribbean oceanic crust along the North American–Caribbean Plate bound- onto the blocks; thrusting of metamorphic and ary in southern Mexico, Guatemala and northern sedimentary strata was bivergent north and south Honduras. The principal questions addressed are: of the Motagua fault zone (e.g. Meschede & which crustal sections accommodated the large- Frisch 1998; Beccaluva et al. 1995 and references scale sinistral offset along the plate boundary, therein). Since Late Cretaceous–Early Cenozoic, what was the timing of offset and deformation, the MSZ developed into a sinistral wrench zone and in what kinematic framework did it occur? due to the different velocities of the North American What Palaeozoic to Cenozoic geological corre- and Caribbean plates (e.g. DeMets 2001). In lations exist between the Maya Block, the Chortı´s southern Mexico, Guatemala and Honduras this Block, the tectono-stratigraphic complexes (‘ter- still active fault system has dismembered the colli- ranes’) of southern Mexico, and the arc/subduction sional blocks as well as the allochthonous remnants complexes of the northern Caribbean. of the former oceanic crust; the latter comprises shaly me´lange, containing blocks of serpentinized ophiolite fragments, and metamorphic rocks such Northern Caribbean Plate boundary as amphibolite, eclogite, albitite and jadeitite (e.g. Tsujimori et al. 2005). Inferred Cenozoic displace- The Caribbean Plate represents a lithospheric unit ment accommodated along the MSZ is controver- between the North and South American plates. Its sial, but magnetic anomalies within the Cayman western and eastern margins consist of subduction trough suggest a minimum of c. 1100 km; spreading zones with magmatic arcs (Central America rates in the trough were c.3cm/annum from 44 to Isthmus, Lesser Antilles), whereas the northern 30 Ma and c. 1.5 cm/annum thereafter (Rosen- and southern margins correspond to strike–slip crantz et al. 1988). Active faulting and volcanism with subsidiary transpression or transtension zones related to eastward subduction of the Pacific plate (Polochic–Motagua, Cayman, Greater Antilles, overprinted the ophiolite emplacement and intra- North Andean and South Caribbean, e.g. Pindell continental translation features within the crust of et al. 2006). The Motagua Suture Zone (MSZ) of Mexico, Guatemala and Honduras (e.g. Guzmań- southeastern Mexico, Guatemala, and Honduras Speziale 2001). extends from the Pacific Ocean to the Caribbean Sea for c. 400 km east–west and c. 80 km north– south (e.g. Beccaluva et al. 1995), separating the Methods Maya Block from the Chortı´s Block (Fig. 1a, Dengo 1969). This belt actually represents a compo- Methodical and technical aspects of our radiometric site structure, encompassing suture zone(s) with dating that includes U–Pb, Ar–Ar, Rb–Sr, and relics of Mesozoic ocean floor that characterize fission-track geochronology are provided as the northern Caribbean Plate boundary, and Ceno- Supplementary material. Also included in the Sup- zoic fault zones (mainly the Polochic, Motagua, plementary materials is our approach to structural Jocotań–Chamelecoń faults) that link the Cayman analysis of ductile deformation and kinematics, trough pull-apart basin in the east with the subduc- to fault–slip analysis and definition of stress-tensor tion zone of the Pacific plate in the west (Fig. 1). groups in the brittle crust, and a review of the The Maya and Chortı´s Blocks showcase a geo- applied calculation techniques. Methodical and logical history that encompasses Middle Proterozoic technical aspects of our petrology and geothermo- to Quaternary and have long been recognized as barometry are included in the Supplementary key elements in understanding the interaction material along with locations of studied outcrops of Laurentia, Gondwana and the (Proto-)Pacific (‘stops’) and descriptions of analysed samples. Fig. 1. (a) Plate tectonic framework of northern Central America and crustal complexes (‘terranes’) of southern Mexico. Numbers in the Cayman trough give age of transitional to oceanic lithosphere (from Rosencrantz et al. 1988). (b) SRTM digital elevation model of the Motagua suture zone in southern Mexico, Guatemala, and Honduras, highlighting neotectonic structures such as the Polochic, Motagua and Tonala strike–slip faults and NNE-trending grabens (e.g. Sula graben). The Jalpatagua fault zone

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