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 Chortís 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 Chortís Block record the Late Cretaceous–Early Cenozoic collision and eastward sinistral translation of the Greater Antilles arc, the northern Chortís 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 Chuacús 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 Chortís Block contains a significant part of the history of the eastward migration of the Chortís Block; it constitutes the southern part of the arc that facilitated the breakaway of the Chortís Block from the Xolapa complex of southern Mexico. While the Late Cretaceous collision is spectacularly sinistral transpressional, the Eocene–Recent translation of the Chortís 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 Chortís Block, and the terranes of southern Mexico: (i) in the Early–Middle Palaeozoic, the Acatlán complex of the southern Mexican Mixteca terrane, the Rabinal complex of the southern Maya Block, the Chuacús complex, and the Chortís 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 Chuacús complex and the Chortís Block. The separation of North and South America also rifted the Chortís Block from southern Mexico. Rifting ultimately resulted in the formation of the Late Jurassic–Early Cretaceous 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 Chortís Block (Sanarate complex); these complexes share Jurassic metamorphism. The South El Tambor subduction–accretion complex was emplaced onto the Chortís Block probably in the late Early Cretaceous and the Chortís Block collided with 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 Chortís Block shows continuous Early Cretaceous–Recent arc magmatism.

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Supplementary data presented here include concentration and isotopic ratios for U/Pb zircon ages performed by Laser Ablation ICP-MS. An overview of the technique employed for the single crystal laser ablation ICP multicollector mass spectrometric technique (LA-ICP-MS) at the Arizona Laserchron Center is included. ANALYTICAL TECHNIQUES After crushing and pulverizing samples, zircon grains were concentrated by Wilfley ® shaking table, Frantz ® isodynamic separator, methylene iodide and hand picking. Final zircon concentrates were sieved and grains >40 μm were selected for analysis. Zircon unknowns and standards were mounted on the center of 1 inch phenolic Orings and polished to expose grain interiors. Analyzed detrital zircons were selected DR2009238 randomly. Each measurement cycle consisted of one 20s integration on every centered peak with the laser off for background counts, twenty 1s integrations during mineral blasting, and ~30s of purging. Zircons were ablated with a New Wave Research DUV193 ArF Excimer laser (wavelength = 193 nm). The laser beam was operated with ~32mJ energy (at 23kV), pulse rate of 9Hz, and spot size of 35μm or 50 μm depending on size and complexity of zircons. The generated pit was ~10 μm deep. Ablated material was carried in helium gas into an Isoprobe ICPMS from GV Instruments. U, Th and Pb isotopes were analyzed simultaneously in static mode using Faraday collectors for 238 U, 232 U, 208 Pb, 207 Pb and 206 Pb, and using an ion counter for 204 Pb. Contributions to the 204 mass by Hg were removed by subtracting background counts. Common Pb corrections were calculated from 204 Pb measurements and assuming an initial isotopic composition according to the Pb evolution curve by Stacey and Kramers (1975). Fragments of NIST 610 trace element glass were analyzed with every sample to determine concentrations of U and Th. Five Sri Lanka zircon standards (564±4 Ma, 2sigma error) were analyzed before each sample and once every five unknowns.

The Guatemala suture zone is a major east-west left-lateral strike slip boundary that separates the North American and Caribbean plates in Guatemala. The Motagua fault, the central active strand of the suture zone, underwent two major collisional events within a system otherwise dominated by strike-slip motion. The first event is recorded by high-pressure/low temperature (HP/LT) eclogites and related rocks that occur within serpentinites both north and south of the Motagua fault. Lawsonite eclogites south of the fault are not significantly retrograded and give 40 Ar/ 39 Ar ages of 125-116 Ma and Sm-Nd mineral isochrons of 144-132 Ma.Eclogites north of the fault give similar Sm-Nd isochron ages (131-126 Ma) but otherwise differ in that they are strongly overprinted by a lower pressure assemblage and, along with associated HP/LT rocks, give much younger 40 Ar/ 39 Ar ages of 88-55 Ma indicating a later amphibolite facies metamorphic event. We propose therefore that all serpentinite hosted eclogites along the Motagua fault formed at essentially the same time in different parts of a laterally extensive Lower Cretaceous forearc subduction system, but subsequently underwent different histories. The southern assemblages were thrust southwards (present coordinates) immediately after HP metamorphism whereas the northern association was retrograded during a later collision that thrust it northward at ca. 70 Ma. They were subsequently juxtaposed opposite each other by major strike slip motion. This model implies that the HP rocks on opposing sides of the Motagua fault evolved along a plate boundary that underwent both dip slip and strike slip motion throughout the Late Cretaceous as a result of oblique convergence. The juxtaposition of a convergent and strike slip system means that HP/LT rocks within serpentinites can be found at depth along much of the modern Guatemala suture zone and its eastward extension into the northern Caribbean. Both sets of assemblages were exhumed relatively recently by the uplift of mountain ranges on both sides of the fault caused by movement along a restraining bend. Recent exhumation explains the apparently lack of offset of surface outcrops along a major strike slip fault.

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