27-9 Timing, Evolution, and Geodynamic Setting of the Sierra Madre Oriental at the latitude of Linares, Nuevo Leon.

Session: Evolution of Cordilleran-type orogenic systems

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Abstract:

The geology of the northern Sierra Madre Oriental is readily accessible along a series of e-w highways that extend from the Sierra San Julián, Gro, to Linares, N.L. The dominant structural style along this traverse is a detached, box-style folding globally associated with movement along an evaporite detachment.  These folds involve strata of Middle Jurassic to early Cenozoic age.  Thrust imbrications of these strata are rare, hence it is properly referred to as a fold belt in this region.  The traverse crosses four major structural domains. From west to east these are The San Julián uplift, the central fold belt, the Galeana uplift, and the eastern salt basin.  Contraction in this area began prior to 80 Ma, when the Sierra El Astillero folds on the eastern fringe of the central fold belt were intruded by the Rocamontes pluton.  Folding snd salt withdrawal in the eastern salt basin also began at this time.  Deformation generally proceeded from west to east, but jumped around from area to area and therefore was not a steady progression. Overall shortening on this detachment system is estimated to be 50 km, or about 25% along this traverse. This part of the Mexican orogen may be unique among contractional systems as it was contracting while being buried beneath up to 6 km of overburden.  Overburden accumulation was greatest at the toe of this system, not the hinterland. The driving mechanism for both the contraction and subsidence is most likely coupling between the subducting Farallon plate and overriding North American plate, with the locus of greatest subsidence coinciding with the downturn of the subducted slab. This is analogous to the interaction ongoing today between the North American and the Cocos plates along the Middle America trench.

Geological Society of America Abstracts with Programs. Vol. 58, No. 3, 2026

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