Tectono-stratigraphic response of the Sandino Forearc Basin (N-Costa Rica and W-Nicaragua) to episodes of rough crust and oblique subduction

The southern Central American active margin is a world-class site where past and present subduction processes have been extensively studied. Tectonic erosion/accretion and oblique/orthogonal subduction are thought to alternate in space and time along the Middle American Trench. These processes may cause various responses in the upper plate, such as uplift/subsidence, deformation, and volcanic arc migration/ shut-off. We present an updated stratigraphic framework of the Late Cretaceous– Cenozoic Sandino Forearc Basin (SFB) which provides evidence of sedimentary response to tectonic events. Since its inception, the basin was predominantly filled with deep-water volcaniclastic deposits. In contrast, shallow-water deposits appeared episodically in the basin record and are considered as tectonic event markers. The SFB stretches for about 300 km and varies in thickness from 5 km (southern part) to about 16 km (northern part). The drastic, along-basin, thickness variation appears to be the result of (1) differential tectonic evolutions and (2) differential rates of sediment supply. (1) The northern SFB did not experience major tectonic events. In contrast, the reduced thickness of the southern SFB (5 km) is the result of at least four uplift phases related to the collision/accretion of bathymetric reliefs on the incoming plate: (i) the accretion of a buoyant oceanic plateau (Nicoya Complex) during the middle Campanian; (ii) the collision of an oceanic plateau (?) during the late Danian–Selandian; (iii) the collision/accretion of seamounts during the late Eocene–early Oligocene; (iv) the collision of seamounts and ridges during the Pliocene–Holocene. (2) The northwestward thickening of the SFB may have been enhanced by high sediment supply in the Fonseca Gulf area which reflects sourcing from wide, high relief drainage basins. In contrast, sedimentary input has possibly been lower along the southern SFB, due to the proximity of the narrow, lowland isthmus of southern Central America. Moreover, two phases of strongly oblique subduction affected the margin, producing strike-slip faulting in the forearc basin: (1) prior to the Farallon Plate breakup, an Oligocene transpressional phase caused deformation and uplift of the basin depocenter, triggering shallowing-upward of the Nicaraguan Isthmus in the central and northern SFB; (2) a Pleistocene–Holocene transtensional phase drives the NW-directed motion of a forearc sliver and reactivation of the graben-bounding faults of the late Neogene Nicaraguan Depression. We discuss arguments in favour of a Pliocene development of the Nicaraguan Depression and propose that the Nicaraguan Isthmus, which is the apparent rift shoulder of the depression, represents a structure inherited from the Oligocene transpressional phase

Numerical recognition of alignments in monogenetic volcanic areas: Examples from the Michoacán-Guanajuato Volcanic Field in Mexico and Calatrava in Spain

10 páginas, 8 figuras.-- El PDF es la versión de autor.Identification of geological lineaments using numerical methods is a useful tool to reveal structures that may not be evident to the naked eye. In this sense, monogenetic volcanic fields represent an especially suitable case for the application of such techniques, since eruptive vents can be considered as point-like features. Application of a two-point azimuth method to the Michoacán-Guanajuato Volcanic Field (Mexico) and the Calatrava Volcanic Province (Spain) demonstrates that the main lineaments controlling the distributions of volcanic vents (~ 322° in Calatrava and ~ 30° in Michoacán) approach the respective main compressional axes that dominate in the area (i.e. the Cocos–North America plates convergence and the main Betics compressional direction, respectively). Considering the stress fields that are present in each volcanic area and their respective geodynamic history, it seems that although volcanism may be a consequence of contemporaneous extensional regimes, the distribution of the volcanic vents in these kinds of monogenetic fields is actually controlled by reactivation of older fractures which then become more favourable for producing space for magma ascent at near-surface levels.This work is part of project CGL2008-02638/BTE, funded by the Ministry of Science and Innovation of Spain.Peer reviewe

Paleomagnetic and isotope data from southern Mexico and the controversy over the pre-neogene position of Baja California

Se revisan los datos paleomagneticos e isotópicos del suroccidente de Mexico y de Baja California (BC), con el objeto de evaluar las propuestas de desplazamientos significativos hacia el norte de segmentos de Ia margen continental del occidente de México y Norteamérica. Los datos indican una relativa estabilidad tectónica del suroccidente de México desde el Cretacico medio. No existen rotaciones de los polos paleomagnéticos en sentido horario que apoyen Ia interpretación de allas de desplazamiento lateral derecho; por el contrario, se reconocen algunas rotaciones en sentido antihorario que indican fallas de desplazamiento lateral izquierdo. Los datos geocronologicos de los plutones no deformados a lo largo de Ia margen suroccidental de México indican una clara tendencia decreciente en las edades de intrusión desde Puerto Vallarta ("'100 Ma) hasta Acapulco ("'55-33 Ma). Las edades reportadas previamente para Baja California varian de 120 Ma a 90 May no muestran una tendencia discernible a lo largo de la península. La sistemática de Nd y Sr revela que el batolito de Puerto Vallarta alcanza en su porción oriental un grado de contaminación cortical alto y edades modelo (TDM) superiores a 1Ga. El Batolito de Los Cabos muestra una contaminación cortical y una edad modelo relativamente altas, (TDM = 0.9 Ga) con una edad de intrusión esencialmente igual a Ia del Batolito de Puerto Vallarta. Los datos anteriores sugieren una posición de BC para el Cretácico Tardío-Paleoceno similar a la del inicio de la apertura del Golfo de California, solo con desplazamiento latitudinales menores. doi: https://doi.org/10.22201/igeof.00167169p.1992.31.3.112

Assessment of the Greek legislaton concerning nonhuman animals centered on th Laws 4039/2012 and 4235/2014

«Να φέρεστε ευγενικά απέναντι στα ζώα, διότι η ευγένεια και η καλοσύνη έναντι των ζώων οδηγεί στην ευγένεια και την καλοσύνη έναντι των συνανθρώπων» κι άλλωστε τι σημασία έχει αν τα ζώα είναι έλλογα ή άλογα; «Σημασία έχει ότι υποφέρουν ή ικανοποιούνται όπως οι άνθρωποι». Καντιανά ή ωφελιμιστικά το μη ανθρώπινο ζώο απέκτησε μια κάποια υπόσταση με τη συνδρομή της ηθικής φιλοσοφίας. Από καταβολής κόσμου έως σήμερα το ζώο υπήρξε το έμβιο, αισθανόμενο ον, το οποίο ο άνθρωπος χρησιμοποίησε και χρησιμοποιεί κατά βούληση θεωρώντας το οιονεί αντικείμενο και θεμελιώνοντας τη θεώρησή του στη διαφορά και στην ομοιότητα συγχρόνως. Διαφορά και ομοιότητα υπηρέτησαν αμφότερες το σκοπό της ατέρμονης εκμετάλλευσης έως και κακομεταχείρισης του μη ανθρώπινου ζώου ως άλλοθι και νομιμοποιητική βάση τους. Το ίδιο πλάσμα που ως μη έλλογο μπορεί να χρησιμοποιείται ως εργαλείο ή τροφή είναι κατάλληλο για πειράματα με στόχο την παρασκευή φαρμάκων για ανθρώπινη χρήση. Οι λόγοι που οδήγησαν σ’ αυτήν την αντίληψη δείχνουν να είναι θεϊκοί και ανθρώπινοι μαζί. Σύμφωνα με τη Γένεση, για παράδειγμα, ο άνθρωπος κυριαρχεί «επί όλων των κτηνών» και από την άλλη πλευρά ο άνθρωπος αντελήφθη την κυριαρχία με τον τρόπο που έκρινε προσφορότερο για τον ίδιο. Παρόλα αυτά υπέρ της βελτίωσης της θέσης του μη ανθρώπινου ζώου τάχτηκαν ήδη από την ελληνική αρχαιότητα πολλές από τις σημαντικότερες προσωπικότητες που κατοίκησαν στην πορεία των αιώνων αυτόν εδώ τον πλανήτη. Ο δρόμος από τον Πυθαγόρα έως τον P. Singer και τον T. Regan έμοιαζε ατελείωτος αλλά διανύθηκε. Υπό την επίδραση των ανακαλύψεων, εφευρέσεων και ιδεών το πλήθος των κοινωνικών μεταβολών που έλαβαν χώρα με ταχύτητα μεγάλη στη νεωτερικότητα και ιλιγγιώδη στα χρόνια που ακολούθησαν τον Β’ Παγκόσμιο Πόλεμο προκλήθηκε ή ανέδειξε μια σειρά κινημάτων με σκοπό τη βελτίωση της υπόστασης του ανθρώπινου όντος. Όλα τους είχαν έρεισμα φιλοσοφικό- ηθικό. Ο άνθρωπος ως αυτόνομη οντότητα ή αυτοσκοπός αξίζει και δικαιούται σεβασμό · η ελευθερία της έκφρασης και η ελευθερία έκφρασης της ατομικότητας του ανθρώπου οφείλει να ενθαρρύνεται και να περιφρουρείται · αυτές είναι οι βασικές θέσεις των κατ’ ουσία ιδρυτών, του Ι. Καντ και του Τζ. Σ. Μιλ αντίστοιχα, των δύο κύριων φιλοσοφικών ρευμάτων της νεωτερικότητας με απήχηση και στην μετανεωτερικότητα. Ο επιμέρους κλάδος της φιλοσοφίας του δικαίου δεν μπορούσε να μείνει ανεπηρέαστος και οι νομοθεσίες χωρών του δυτικού, λεγόμενου, κόσμου εναρμονίστηκαν σταδιακά με τα φιλοσοφικά αιτήματα. Καθώς οι ίδιες αυτές φιλοσοφικές σχολές πρόσφεραν τα επιχειρήματα και για την βελτίωση της θέσης του μη ανθρώπινου ζώου, οι νομοθέτες διάφορων κρατών λαμβάνοντας υπόψη την προοδευτική μετατροπή της ιδέας σε πρακτικό αίτημα συμπεριέλαβαν και τη ρύθμιση ζητημάτων που αφορούν την μεταχείριση του μη ανθρώπινου ζώου. Ο έλληνας νομοθέτης δεν υστέρησε έστω κι αν αργοπόρησε κάπως. Θέσπισε τους νόμους 4039/2012 και 4235/2014 με σκοπό την προστασία του μη ανθρώπινου ζώου. Σε συνδυασμό με άλλα σχετικά νομοθετήματα φαίνεται να ακολούθησε σε μια περίπτωση την ωφελιμιστική σε άλλη την καντιανή, ηθική θεμελίωση, όχι πάντα με τρόπο ευδιάκριτο του χαρακτήρα της μιας ή της άλλης φιλοσοφικής οπτικής, αλλά οπωσδήποτε σε ό,τι αφορά τους δύο παραπάνω νόμους με διάθεση αναχαίτισης της ανθρώπινης αυθαιρεσίας, πράγμα που αναδεικνύουμε στο παρόν πόνημα και πραγματευόμαστε κριτικά. Παραθέτουμε επιπλέον τη δική μας τοποθέτηση αναφορικά με τη σύγχρονη συζήτηση, η οποία έχει ως αντικείμενο την εν γένει θέση και σχέση του μη ανθρώπινου ζώου με τον ανθρώπινο νόμο.“You should behave kindly to animals, because politeness and kindness towards animals leads to politeness and kindness towards fellow human beings”. Besides, what does it matter if animals are rational or nonrational? “What matters is that they suffer or enjoy” as people do. Either in Kantian or in utilitarian way the non-human animals have acquired some substance with the contribution of ethics. From foundation of the world to date the non-human animal has always been the living sentient being which humans have used and still use at will by considering it as quasi object and they support their attitude by means of difference and similarity at the same time. Difference and similarity both have served the purpose of endless exploitation and abuse to the non-human animal as their alibi and legitimizing basis. The same creature which as object can be used as tool or food is also appropriate for experiments with the objective of the preparation of medication for human use. The reasons which have led to this perception seem to be divine and human together. According to Genesis for example “the man dominates all beasts” and on the other hand humans have perceived the domination in the most convenient way for themselves. However, as early as since the Greek antiquity, many of the most significant personages who have lived on this planet over the centuries have advocated the improvement of the position of the non-human animal. The distance from Pythagoras to P. Singer and T. Regan seemed to be endless but it has been covered. Under the influence of discoveries, inventions and ideas the numerous social changes that took place rapidly in modernism, with breathtaking speed in the years following the Second World War, were brought about or they brought out a series of social movements with view to improve the status of human being. All of them had philosophical-ethical footing. Human beings as autonomous entities and ends in themselves deserve and have the right to be respected; the expression freedom and the freedom of individuality expression ought to be encouraged and guarded; these are the basic philosophical positions Kant’s and Mill’s respectively, who arein essence the founders of the two main philosophy schools in modernism with resonance in postmodernism. Philosophy of law as individual branch of philosophy couldn’t have stayed unswayed and the legislation of countries of the so called western world harmonized with the philosophical requests gradually. As the same philosophical schools have also offered the argumentation for the improvement of the status of non-human animals, the legislators of several countries taking into account the progressive conversion of the idea into practical request have included the regulation of issues concerning the treatment of non-human animals too. The Greek legislator hasn’t lagged behind, even if they have lingered. They adopted Law 4039/2012 and Law 4235/2014 in order to protect the non-human animals. In conjunction with other relevant legislation they seem to have followed either the Kantian or the utilitarian approach, not always in a clear way regarding the character of one or another approach, but certainly in what concerns the two laws above with preposition to restrain the human arbitrariness, which we highlight and discuss critically in the present piece of work. We also expose our own point of view regarding the contemporary discussion which has as subject the position and the relation of the non-human animal to the human law in general

Jurassic-Cretaceous paleogeographic evolution of the northern Mixteca terrane, southern Mexico

Con base en un análisis estratignifico realizado en tres diferentes áreas del norte del Estado de Oaxaca y sur del de Puebla, se presenta un modelo de la evolucion paleogeográfica para el Jurásico-Cretácico de la porción norte del Terreno Mixteca. Las capas más antiguas de la secuencia mesozoica (foarciano (?)-Aaleniano), expuestas en el área de Tezoatlán-El Rosario, consisten de estratos de conglomerados, areniscas, limolitas y lutitas con algunas capas de carbón. Estas capas se acumularon después del cambio de un regimen tectónico de levantamiento, activo desde el Triásico Temprano, a un regimen tectónico tensional con hundimiento. En respuesta a este cambio se forma un grupo de cuencas tectónicas, acompañadas por el desarrollo de un sistema fluvial con pendiente general hacia el sur. La secuencia continental acumulada durante el Jurásico Medio en esta porción del Terreno Mixteca tiene un espesor máximo de 2,300 m y muestra fuertes cambios laterales que representan transiciones de abanicos aluviales a llanuras de inundación y depósitos de canal. Durante el Bajociano y Bathoniano, esta región experimento transgresiones marinas de corta duración, provenientes del Pacífico, las cuales inundaron la parte sur del Terreno Mixteca hasta una línea situada entre Tezoatlán y Huajuapan de León. Del Calloviano al Hauteriviano dominaron condiciones de sedimentación marinas someras con depósitos calcáreos y detríticos en la parte sur de la región estudiada, previamente ocupada por el sistema fluvial. La paleogeografia del Jurasico Tardio se caracterizó por una bahía somera (Bahia de Tlaxiaco) conectada hacia el sur con el Océano Pacifico. En algún momento entre el Tithoniano y el Valanginiano, es posible que se haya establecido por primera vez una comunicación entre esta bahía y los cuerpos de agua conectados con el Golfo de México. No existen evidencias estratigráficas para sustentar la interpretación de una conección marina entre la Bahía de Tlaxiaco y el área correspondiente al sur de la Sierra Madre Oriental para el Calloviano y la mayor parte del Jurasico Tardío. Para el Barremiano-Aptiano no existen indicios de sedimentación marina en la mayor parte del Terreno Mixteca, únicamente hacia el norte, en San Juan Raya, se ha reportado una secuencia marina continua del Valanginiano al Aptiano. Para este tiempo, en la región de Santo Domingo Tonalá, ocurrieron episodios de volcanismo monogénetico subáereo. A partir del Albiano y hasta probablemente el Turoniano, se desarrolló una amplia plataforma calcárea sobre los terrenos Mixteca y Oaxaca, la cual probablemente se extendía hasta la plataforma de Actopan situada al norte de la actual Faja Volcánica Transmexicana. En los tiempos posteriores al Turoniano ocurrió un levantamiento general asociado a plegamiento, que afectó la porción norte del Terreno Mixteca. Unicamente en la parte suroeste de este terreno parece haberse desarrollado una sedimentación continua hasta el Maestrichtiano. doi: https://doi.org/10.22201/igeof.00167169p.1993.32.3.52

A New Species of \u3ci\u3eIstiodactylus\u3c/i\u3e (Pterosauria, Pterodactyloidea) from the Lower Cretaceous of Liaoning, China

Istiodactylus sinensis, sp. nov., from the Jiufotang Formation of Liaoning, People\u27s Republic of China, is described on the basis of a single nearly complete and nearly osteologically adult specimen. This is the tenth pterosaur described from this formation and the eighteenth pterosaur species described from northeastern China in almost half as many years. The species is placed in the Istiodactylidae, which was previously a monospecific family of pterodactyloid pterosaurs known only from the Isle of Wight, England. The new form is distinct from the two other istiodactylid species. It is smaller, more plesiomorphic, and younger than Istiodactylus latidens, but larger and more derived than the contemporaneous Nurhachius ignaciobritoi. Istiodactylus sinensis is very similar to I. latidens, so that almost all of the previous autapomorphies of I. latidens are now synapomorphies of Istiodactylus. They differ most in that I. sinensis is much smaller than I. latidens. The length of the wingspan, skull, and most of the preserved limb elements of I. sinensis are about 63 percent of the wingspan and elements of I. latidens. This new specimen demonstrates that Istiodactylus is diagnosed by, among other characters, a dorsoventrally depressed but not laterally expanded rostrum, and the presence of a suborbital vacuity. A dorsal deflection of the alveolar margins of the jaws and a humerus between 55 percent and one and a half times the length of metacarpal IV are synapomorphies uniting the Istiodactylidae and the Anhangueridae