Publication Date:
2009-12-28
Description:
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 Chortis 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 Chortis Block record the Late Cretaceous-Early Cenozoic collision and eastward sinistral translation of the Greater Antilles arc, the northern Chortis 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 Chuacus 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 Chortis Block contains a significant part of the history of the eastward migration of the Chortis Block; it constitutes the southern part of the arc that facilitated the breakaway of the Chortis Block from the Xolapa complex of southern Mexico. While the Late Cretaceous collision is spectacularly sinistral transpressional, the Eocene-Recent translation of the Chortis 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 Chortis Block, and the terranes of southern Mexico: (i) in the Early-Middle Palaeozoic, the Acatlan complex of the southern Mexican Mixteca terrane, the Rabinal complex of the southern Maya Block, the Chuacus complex, and the Chortis 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 Chuacus complex and the Chortis Block. The separation of North and South America also rifted the Chortis 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 Chortis Block (Sanarate complex); these complexes share Jurassic metamorphism. The South El Tambor subduction-accretion complex was emplaced onto the Chortis Block probably in the late Early Cretaceous and the Chortis 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 Chortis Block shows continuous Early Cretaceous-Recent arc magmatism.
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