ABSTRACT Defining temporal and spatial distribution of shortening is critical to reconstruct past plate motions and to examine mechanical coupling processes at convergent plate boundaries. Understanding the collisional evolution of the British Mountains and Beaufort-MacKenzie basin in the northern Alaska–Yukon region is key for the geodynamics of the Arctic region. With the aim to resolve the exhumation history of this region, we present the first zircon fission-track and (U-Th)/He analyses on apatite and zircon from the Neruokpuk Formation (ca. 720–485 Ma), which forms the orogenic basement of the British Mountains. Zircon fission-track ages show partial resetting, indicating the Proterozoic basement did not reside at temperatures above 240 °C. Thermal modeling of zircon and apatite (U-Th)/He data indicates that our samples reached this maximum temperature at ca. 100 Ma. The onset of the Brookian collision is indicated by exhumation from ca. 80 Ma. A total exhumation of 7–8.5 km since the Late Cretaceous is inferred. Apatite (U-Th)/He ages of ca. 50 Ma show that exhumation was less than 2.5 km since the early Eocene. We infer from a comparison with the temporal evolution of exhumation from adjacent orogenic domains that shortening progressively shifted northward from the British Mountains to the Barn Mountains and offshore in the Beaufort Sea during the Paleocene. Along-strike variations in the architecture of the rifted margin of Arctic Alaska is suggested to have exerted a strong control on the structural styles and observed exhumation patterns.

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 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. Supplementary material: Analytical methods and data, and sample description are available at http://www.geolsoc.org.uk/SUP18360.