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The El Salvador plutonic complex is a 9.2 km2 circular body within the Sierra de Tamaulipas, part of the Eastern Mexican Alkaline Province (EMAP). Three alkaline magmatic suites were identified from El Salvador from the geochemical analysis of 20 samples. Suite A (SiO2 = 58.3–65.3 wt.%) is ferroan (Fe* = 0.761–0.873) and alkalic (MALI = 4.83–9.89). In contrast, Suites B (SiO2 = 52.5–60.8 wt.%; Fe* = 0.680–0.756) and C (SiO2 = 50.5–67.1 wt.%; Fe* = 0.616–0.749) are magnesian. Suite B is alkali-calcic (MALI = -2.18–4.64), while Suite C is alkalic (MALI = 4.48–8.59). All suites display arc-related signatures. U-Pb and fission-track geochronology data reveal two uplift episodes during the cooling history of Suite A. One in the Late Eocene was based on U-Pb zircon (38.42 ± 0.21 Ma) and titanite ages (35.54 ± 3.77 Ma). The other was during the Oligocene from U-Pb apatite (29.9 ± 6.54 Ma) and fission-track titanite (30.2 ± 5.53 Ma) and apatite ages (32.7 ± 7.06 Ma). Integrating the arc-related signatures of El Salvador rocks with the well-documented Palaeogene arc magmatism of the Sierra Madre del Sur, we propose that the mantle beneath the EMAP experienced metasomatism during the Early Permian (and possibly the Early Jurassic) but not after the Late Cretaceous, ruling out Cenozoic slab subduction in eastern Mexico. In the absence of a slab to explain the El Salvador magmatism, we suggest a long-lasting, widespread mantle upwelling beneath Mexico's northern half in response to the Farallon slab's break-up. Under this context, the westward drift of the North American plate led to the Mexican Foreland Basin lithosphere reaching this massive mantle upwelling in late Eocene times to produce the EMAP magmatism. [ABSTRACT FROM AUTHOR]

Sandstone petrography, zircon and apatite U-Pb geochronology, and apatite geochemistry of Early Cretaceous siliciclastic turbidites interbedded with basalt (Chivillas Formation) in the southern Sierra Madre Oriental, Mexico, indicate local provenance from westerly basement sources. Three main detrital populations were observed in both the zircon and apatite geochronology: Meso–Neoproterozoic, Carboniferous–Permian, and Early Cretaceous. Apatite Sr/Y vs light rare earth element discrimination diagrams indicate that most Precambrian grains have affinity with high-grade metamorphic rocks and most Phanerozoic grains with igneous rocks. These results are consistent with derivation from exposed crystalline sources within the Acatlán-Oaxacan block including the Grenvillian Oaxacan Complex, the East Mexico Arc, and the Early Cretaceous continental arc. The compositional disparities observed in individual samples reflect differences in source of individual turbiditic flows comprising the Chivillas Formation. We surmise that various rivers from the northern and southern Acatlán-Oaxacan block drained into the basin during the Early Cretaceous. Furthermore, detrital apatite fission-track analyses of Chivillas sandstones yielded mostly 42–40 Ma ages (Eocene) that post-date the shortening of the Mexican orogen in the southern Sierra Madre Oriental. Thermal models calculated based on track lengths indicate rapid exhumation of Chivillas rocks at 46–36 Ma, which is the time of the development of the Tehuacán Valley and reactivation of the Oaxaca Fault System as a normal fault. [ABSTRACT FROM AUTHOR]

In this study, we present apatite fission-track results obtained for ten rock samples collected from three different areas across the Sierra Madre del Sur, southern Mexico. The central objective of our study is the timing of the exhumation event that took place in southern Mexico during Late Cretaceous–Palaeogene time. The thermochronometric data obtained during this work indicate that a Late Cretaceous–Eocene cooling is recorded within the Sierra Madre del Sur, and this is interpreted as resulting from exhumation, an orogenic event that is contemporaneous with the Laramide sensu lato (or the Mexican Orogeny). The fission-track ages become younger from west to east across the Sierra Madre del Sur, whereas the cooling rates also increased in the same direction approximately during Campanian–middle Eocene time. Here, we suggest that the activity of the major fault systems of southern Mexico, such as the Caltepec and the Oaxaca faults, played a primary role in the development of geological structures and the exhumation of the Sierra Madre del Sur. Active magmatism during the evolution of the Mexican Orogen implicates the subducted Farallon slab as the main driver of crustal thickening. Moreover, the possible influence of the eastward movement of the Chortis Block on the deformation of the Sierra Madre del Sur cannot be ruled out. [ABSTRACT FROM AUTHOR]

We present the first fission‐track results from the Grenvillian Oaxacan Complex, southern Mexico. Time–temperature modelling of the data indicates that two significant Mesozoic cooling episodes are recorded in the Oaxacan Complex and these are interpreted as resulting from exhumation. The older cooling event took place from the Late Triassic to Middle Jurassic and is possible linked to the break‐up of Pangea (including the initial opening of the Gulf of Mexico during the Jurassic). The younger exhumation period in the Early Cretaceous is contemporaneous with the final stages of rifting of the Gulf of Mexico. Key stratigraphic records also provide independent evidence for these exhumation episodes. In our view, both Mesozoic rapid exhumation events were controlled by the activity of the Caltepec Fault Zone and the Oaxaca Fault. Our data suggest that both these large fault systems have remained active since, at least, the Late Triassic. [ABSTRACT FROM AUTHOR]

The Mesa Central of Mexico (MC) is an elevated plateau located 2000 m above sea level in central Mexico, where intrusions outcrop that register the history of exhumation-erosion occurring during the Late Cretaceous-Paleogene. The tectonic history of the region records formation of the Late Cretaceous-Paleogene 'Mexican orogen'; this was followed by extension of the entire region and several plutons were then exhumed. The age and magnitude of the crustal uplift and erosion occurring during exhumation has not been addressed to date. Therefore, this study reports the crystallization and cooling ages of two plutons, the Tesorera Granodiorite and the Comanja Granite, and estimates their emplacement depths. Based on these data, the exhumation age of the Tesorera Granodiorite is estimated to be between ~73 Ma and ~63 Ma at an exhumation rate of ~528 m/m. y. and that of the Comanja Granite is 52 Ma and 48 Ma at an exhumation rate of ~2500 m/m. y. Exhumation-erosion event of the Tesorera Granodiorite was located on the trace of the San Luis-Tepehuanes Fault System and that of the Comanja Granite on the a trace of the El Bajío Fault System. Furthermore, the high exhumation rate in the Comanja Granite suggests that gravitational collapse played an important role during exhumation. [ABSTRACT FROM AUTHOR]

This study reports the first LA-ICP-MS-based apatite fission track age data from the Toarcian–Oxfordian Todos Santos Formation sandstones exposed in the Sierra de Chiapas (SCH), SE Mexico. Single-grain fission track ages obtained from four rock samples vary between 232 ± 31 (1σ) and 40 ± 3 (1σ) Ma, indicating partial resetting of detrital apatite populations by post-depositional heating during diagenesis. Decomposed data were interpreted as follows: (a) cooling of the sediment source area at 203 ± 7 (1σ) and 163 ± 3 (1σ) Ma, which are respectively coincident with the late Permian–Triassic thermo-tectonic event and Early–Middle Jurassic arc volcanism that affected the Chiapas Massif Complex; and (b) a post-burial cooling period (with variable cooling rates of <3°C Ma–1) in the range of ~83–51 Ma controlled by a Late Cretaceous–early Eocene tectonic activity, which can be correlated with the Laramide orogeny that occurred along central and northern Mexico during the same period of time (i.e. from 85–80 to 50–40 Ma). The results obtained in the present study, as well as previously published data, indicate that the SCH has experienced a multi-episodic thermo-tectonic evolution with at least four main stages. [ABSTRACT FROM PUBLISHER]