Timing of the Cenozoic basins of Southern Mexico and its relationship with the Pacific truncation process: Subduction erosion or detachment of the Chortís block

• Published in: Journal of South American earth sciences 2018-04, Vol.83, p.178-194
• Main Authors: Silva-Romo, Gilberto, Mendoza-Rosales, Claudia Cristina, Campos-Madrigal, Emiliano, Hernández-Marmolejo, Yoalli Bianii, de la Rosa-Mora, Orestes Antonio, de la Torre-González, Alam Israel, Bonifacio-Serralde, Carlos, López-García, Nallely, Nápoles-Valenzuela, Juan Ivan
• Format: Article
• Language: English
• Subjects: Fault basin; Fault system; Magmatic zircon; Margin truncation; Strike slip fault
• ISSN: 0895-9811; 1873-0647
• DOI: 10.1016/j.jsames.2018.01.007

In the central sector of the Sierra Madre del Sur in Southern Mexico, between approximately 36 and 16 Ma ago and in the west to east direction, a diachronic process of the formation of ∼north-south trending fault-bounded basins occurred. No tectono-sedimentary event in the period between 25 and 20 Ma is recognized in the study region. A period during which subduction erosion truncated the continental crust of southern Mexico has been proposed. The chronology, geometry and style of the formation of the Eocene Miocene fault-bounded basins are more congruent with crustal truncation by the detachment of the Chortís block, thus bringing into question the crustal truncation hypothesis of the Southern Mexico margin. Between Taxco and Tehuacán, using seven new Laser Ablation- Inductively-coupled plasma mass spectrometry (LA-ICP-MS) U-Pb ages in magmatic zircons, we refine the stratigraphy of the Tepenene, Tehuitzingo, Atzumba and Tepelmeme basins. The analyzed basins present similar tectono-sedimentary evolutions as follows: Stage 1, depocenter formation and filling by clastic rocks accumulated as alluvial fans and Stage 2, lacustrine sedimentation characterized by calcareous and/or evaporite beds. Based on our results, we propose the following hypothesis: in Southern Mexico, during Eocene-Miocene times, the diachronic formation of fault-bounded basins with general north-south trend occurred within the framework of the convergence between the plates of North and South America, and once the Chortís block had slipped towards the east, the basins formed in the cortical crust were recently left behind. On the other hand, the beginning of the basins’ formation process related to left strike slip faults during Eocene-Oligocene times can be associated with the thermomechanical maturation cortical process that caused the brittle/ductile transition level in the continental crust to shallow. [Display omitted] •Chortis block detachment trigger fault-bounded basins formation on South Mexico.•Diachronic fault-bounded basins formation process between Eocene and Miocene.•Fault-bounded basins formation coeval process with cenozoic magmatism of South Mexico.•The basins formation process include time of erosion by subduction without any sequel.•Basins formation argue against truncation of Southern Mexico by subduction erosion.