Exhumation and topographic evolution of the Chiapas Massif Complex (southern Mexico) constrained by thermochronologic data modeling along vertical profiles

Thermochronometry is used to better understand the processes responsible for Cenozoic magmatism and exhumation of the Chiapas Massif Complex that spans a diffuse triple junction between the Caribbean, North American and Cocos plates. A combination of zircon U-Pb, apatite fission tracks, (U-Th)/He as well as numerical modeling show contrasting histories. Exhumation started earlier in the south (-16 Ma) relative to the north (-9 Ma). Northern exhumation is related to activity on the Tonal & PRIME;a fault system, while to the south it may be correlated with transpressive deformation in Chiapas fold-and-thrust belt. The southern block also experienced significant topographic growth from -5 Ma to -1 Ma followed by intense erosion. Overall, the pattern of uplift agrees with the 'closing zipper' model in which a forearc sliver is progressively incorporated to the North American plate. Thermal models also support a Pleistocene decrease in topography consistent with independent paleoenvironmental and geomorphologic evidence.