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Neotectonic activity in the western margin of the Sierra Madre Oriental in northeastern Mexico was evaluated using geomorphological, geological, structural, and seismological analyses. We evaluated recent tectonic evidence in the basin of the Potosí Valley related to the Santo Domingo Fault System (SDFS), which is one of the largest active extensional fault zones documented so far in the transition zone between the Basin and Range and the Sierra Madre Oriental provinces. Two indices were used in the geomorphological analysis: transverse topographic basin asymmetry (T) and mountain front sinuosity (Smf). The results show that the studied basin is slightly tilted to the WSW, consistent with the typical basin deformation pattern in the Basin and Range province. Structural data collected in the field unveil a NW–SE striking fault system, geometrically and kinematically similar to the Cenozoic lineaments of the Basin and Range province. The local stress tensor calculated in this study indicates an extensional tectonic regime, suggesting S V > S NW > S NE . Analysis defines an azimuth trend of 298° and 036° for σ 2 (S Hmax) and σ 3 S hmin , respectively. According to the results, the SDFS is well orientated for possible future reactivation as a normal fault system. We estimate that a segmented rupture of the SDFS could produce seismic events on the order of magnitude 5 < Mw < 6. Considering a continuous rupture (~ 42 km) of the SDFS in a single event, an earthquake of Mw 7.0 could be expected. The results are essential to estimate seismic hazards in northeastern Mexico, including important urban areas, such as Monterrey, Nuevo León, and Saltillo, Coahuila. [ABSTRACT FROM AUTHOR]

The study of the pre-Mesozoic geological history of NE Mexico offers the opportunity to reconstruct the processes that occurred at the NW margin of Gondwana. The Huizachal–Peregrina Anticlinorium, which is located west of Ciudad Victoria (Tamaulipas) is a regional structure produced during the Cretaceous–Palaeogene Laramide Orogeny. Its eroded core exposes Precambrian and Palaeozoic units that together comprise the Sierra Madre Oriental basement. These units are the Neoproterozoic metamorphic Novillo Complex, the Ordovician Peregrina Tonalite, the metamorphic Pennsylvanian Granjeno Complex, and the sedimentary Silurian–Permian Tamatán Group. Aserradero Rhyolite belongs to the Tamatán Group, occurring between the siliciclastic deposits of the Early Mississippian Vicente Guerrero and the Pennsylvanian Del Monte Formations. The studied rhyolites display geochemical characteristics corresponding to high-K, low-Sr, and S-type granitoid rocks that may have been produced by upper-crustal anatexis from a source similar to that of the Novillo Complex. New LA-ICP-MS U–Pb geochronological analysis on zircons separated from the Aserradero Rhyolite yielded Early to Middle Mississippian crystallisation ages of 347.8 ± 2.7 Ma and 340.7 ± 3.6 Ma, confirming that this acidic unit is in its original stratigraphic position despite the pervasive deformation of the Tamatán Group. Based on the correlation with other Carboniferous–Early Permian magmatic complexes in Mexico and Central America, it is suggested that the Aserradero Rhyolite represents an early stage of a precollisional Carboniferous–Permian peri-Gondwanan arc, occurring also in the Las Delicias, Oaxaquia, the Acatlán Complex, the Maya Block, as well as in the buried crystalline basement along the Western Gulf of Mexico. The assembly of the Precambrian and Palaeozoic basement units from the Huizachal–Peregrina Anticlinorium were integrated with the Ciudad Victoria Block, which was dismembered from Oaxaquia and their peripheral units during the Upper-Jurassic Gulf of Mexico opening. [ABSTRACT FROM AUTHOR]

The Huizachal–Peregrina Anticlinorium basement of the Sierra Madre Oriental in north-eastern (NE) Mexico comprises a wide variety of Precambrian and Paleozoic units. A granitic unit, described in this work as the Peregrina Tonalite (PTo), intruded the Neoproterozoic Novillo Gneiss, which is the northernmost expression of the Oaxaquia microcontinent. In contrast, the PTo's contact with the Carboniferous Granjeno Schist is tectonic along vertical faults with a strike-slip component. This Paleozoic lithodeme is part of the Granjeno–Acatlán Belt. The PTo has been described as an orphaned block associated with an enigmatic Carboniferous magmatic arc located along the north-western (NW) margin of Gondwana. In this study, new U–Pb LA–ICP–MS data from PTo zircons included a youngest Late Ordovician (Katian stage) population at 448.8 ± 2.9 Ma, interpreted as the crystallisation age, and an oldest Grenvillian population interpreted as the potential age of its protolith. Additionally, major and trace element concentrations and ratios indicate a link to a continental arc that developed along the NW margin of Gondwana. Given this proposed arc's age and position, a comprehensive model for the development of the NE Mexican basement without the involvement of exotic or orphaned terranes is now proposed. The PTo outcropping near Ciudad Victoria, Tamaulipas, is interpreted to be part of a previously unreported magmatic arc in NE Mexico established during the Late Ordovician, herein described as the Peregrina–Mochonian Orogeny. It represents an extension of the South American Famatinian arc into Mexico. [ABSTRACT FROM AUTHOR]

Abstract  In this work we study the behavior of a time discrete multiregional stochastic model for a population structured in age classes and spread out in different spatial patches between which individuals can migrate. The dynamics of the population is controlled both by reproduction-survival and by migration. These processes take place at different time scales in the sense of the latter being much faster than the former. We incorporate the effect of demographic stochasticity into the population, which results in both dynamics being modelled by multitype Bienaymé–Galton–Watson branching processes. We present a multitype global model that incorporates the effect of both processes and, making use of the existence of different time scales for demography and migration, build a reduced model in which the variables correspond to the total population in each age class. We extend previous results that relate the behavior of the original and the reduced model showing that, given a large enough separation of time scales between demography and migration, we can obtain information about the behavior of the multitype global model through the study of the simpler reduced model. We concentrate on the case where the two systems are supercritical and therefore the expected number of individuals grows to infinity, and show that we can approximate the asymptotic structure of the population vector and the asymptotic population size of the original system through the study of the reduced model. [ABSTRACT FROM AUTHOR]

Dispersing individuals can use conspecifics as indicators of habitat quality and aggregate at traditionally occupied sites, leaving other favourable patches unoccupied. Here we test the predictions of the conspecific-based habitat selection hypothesis on a Spanish great bustard (Otis tarda) metapopulation, currently fragmented due to recent human-induced habitat changes. The number of birds had increased by 23% between 1988 and 1998, but not consistently among leks. Leks that were large in 1988 increased, while those that were small decreased, which suggests that dispersing individuals used the numbers of conspecifics as cues for breeding-site selection. Moreover, leks with high productivity increased, while those with low productivity decreased. Finally, lek distribution was markedly stable throughout the decade, with no establishment of new leks, and suitable habitat patches remained unoccupied, as predicted by the conspecific attraction hypothesis. These results were corroborated by a simulation model which incorporated natal dispersal rates between leks as obtained through radio-tracking of 15 birds that survived throughout their 4-year dispersal period. In conclusion, in spite of the apparent increase in total numbers throughout the decade, both conspecific attraction and local differences in reproductive success contributed to a more aggregated distribution, increasing the species' vulnerability to local catastrophes, and the risks of reduced genetic diversity and extinction of small leks. [ABSTRACT FROM AUTHOR]

Discusses the clinical evolution and management of cystic adenomatoid malformation of the lung (CAML). Type of neoplasms related to CAML; Potential of pleuropulmonary blastoma (PPB); Absence of a proven link between CAML and PPB.