La cuenca de antepais terciaria asociada a la faja plegada y corrida de los Andes Patagónicos entre los 41º y 42º S, SO de Argentina

In Argentina, between 41"-42" S and related to the Andean Patagonian fold and thrust belt, two synorogenic sedimentary sequences were deposited in the Tertiary foreland basin. They represent different moments of the eastward migration of the orogenic front, during upper Eocene to Mio-Pliocene times. The units within the sequence have a characteristic wedge shape, and the proximal facies on the west, prograde to the east and cover the lower distal-medium facies. Structural relationships diplay discordant boundanes near the active orogenic front, which progressively change to concordant towards the foreland. Eocene-Oligocene volcano-sedimentary basa1 sequence contains marine intercalations with Pacific affinities, while Oligocene-lower Pliocene upper sequence has a sedimentary-pyroclastic composition. Based on the age and geometrical characteristics, we proposed a preliminary correlation between proximal to distal facies in the synorogenic formations, and the well known litostratigraphic units outcropping in the El Bolsón valley and the Ñirihuau-Collón Cura basin

Taking Stock of Common Core Math Implementation: Supporting Teachers to Shift Instruction: Insights from the Math in Common 2015 Baseline Survey of Teachers and Administrators

In spring 2015, WestEd administered surveys to understand the perspectives on Common Core State Standards-Mathematics (CCSS-M) implementation of teachers and administrators in eight California school districts participating in the Math in Common (MiC) initiative. From this survey effort, we were able to learn from over 1,000 respondents about some of the initial successes and challenges facing California educators attempting to put in place and support new -- and what some consider revolutionary -- ideas in U.S. mathematics education

Carboniferous stratigraphie and structure oí the Pisuerga-Carrion unit. NW Spain

[Resumen] La Unidad del Pisuerga-Carri6n (UPC) constituye la parte más externa (Cuenca de antepaís) de la Zona Cantábrica (ZC). Los materiales silúrico-dev6nicos, con facies más profundas que los del resto de la ZC, están circunscritos a unidades alóctonas desenraizadas emplazadas como mantos gravitacionales. El sistema carbonífero se caracteriza por la presencia de series potentes con notables variaciones de facies y potencias. Durante el Carbotírtero inferior es característica la prensencia de facies homogéneas y una baja tasa de sedimentación en un ambiente claramente preorogénico. A partir del Namuriese se inicia la sedimentación sinorogénica, abundan las facies originadas a partir de pendientes submarinas o ligadas a relieves emergidos. La persistencia de las condiciones sinorogénicas desde el Namuriense hasta el Estefaniense A y la relativa proliferación de discordancias son también rasgos peculiares de éste área. En este trabajo se propone un esquema de unidades litoestratigráficas, a las que informalmente se asigna la categoría de «grupo~, separadas por discordancias y/o conglomerados de continuidad lateral limitada. Se considera que estos «grupos~ representan «cuñas clásticas~ relacionadas con el emplazamiento de unidades alóctonas concretas, por lo que se propone también un modelo relacionando grupos litoestratigráficos y unidades alóctonas o mantos. Se establecen los rasgos generales de la estructura de la UPC diferenciando dos tipos de manta> (gravitacionales y enraizados), así como las relaciones entre éstos y las diversas generaciones de pliegues y esquistosidades. Por último se propone un modelo de evolución tectonosedimentaria para la UPC, claramente ligado a la evolución estructural de toda la ZC como una cadena arqueada, en el que se considera que el carácter centrípeto de las vergencias en la ZC origina estructuras en la UPC con vergencias igualmente centrípetas así como cuñas elásticas, genéticamente relacionadas, con depocentros situados en posiciones distintas a través del tiempo.[Abstract] The Pisuerga-Carrion Unit (PCU) forms the most external part (foreland basin) of the Cantabrian Zone (Cl). Siluro-devonian rocks with deeper facies than those of the CZ are limited to alloctonous unit wich have been regarded as gravitational nappes. The main characteristic of Carboniferous system is the presence of thick series with remarkable facies and thickness lateral changes. The outstanding feature of lower Carboniferous is the low rate of sedimentation and the fairly uniform sedimentary facies in a preorigenic environment. The synorogenic sedimentation starts in the Namurian, the most frecuent facies are those originated in submarine slopes or those related to subaerial reliefs. The continous synorogenic conditions from Namurian to the Stephanian A stage and the presence of numerous unconformities and lateral sedimentary changes constitue sorne of the characteristics of this area. In this paper a lithostratigraphic sketch are suggested; alllithostratigraphic units were integrated in higher rank units informally called «groups». These «groups» are separated by conglomerates and /or unconformities of limited lateral extension and would represent clastic wedges generated in the front of the nappes Both clastic wedges and nappes are related in this sketch. The general features of the PCU structure are found and two types of nappes (generated by gliding and /or spreading) are stablished, in this way, severa! Generations of folds and cleavages are related with both types of nappes. Lately a tectonosedimentary evolution model for the PCU which would be directly linked to the structural evolution of the Cl. The centripetal character of the vergences in the Cl produced structures (nappes and related folds) in the PCU that have an equally centripetal vergence and originated a synorogenic clastic wedges with depocenters located, in time, in several positions

Late Palaeozoic lithostratigraphy of the Andean Precordillera revisited (San Juan Province, Argentina)

New data on some neopalaeozoic lithostratigraphic units of the central sector of the Argentinean Precordillera are presented. The western Precordillera displays occasional outcrops of siliciclastic rocks of the Late Palaeozoic. These rocks are separated by two main unconformi­ties related to the development of the Chanic (Upper Devonian-early Carboniferous) and Gondwanan (late Carboniferous-early Permian) orogens. A major unconformity marks the beginning of the Andean cycle in middle Permian times. The Del Ratón Formation (800 m) in the studied area is made up of conglomerates and can be divided into two units. The basal part (Lower Member) was deposited in a fjord environment. The Upper Member was generated by an alluvial system that was mainly dominated by upper flow-regime plane beds, whereas its uppermost part accumulated in a fan delta setting. The clast provenance and the main palaeocurrents suggest the existence of a significant topographic high to the W and NW of the present outcrops. The El Planchón Formation (1400 m) is mainly composed of shales and sandstones as a result of sedimentation in a deep-sea fan environment. These lutite-dominated materials graded laterally north­wards into conglomerates in a glacial setting. The Del Ratón and El Planchón formations of the Lower Carboniferous correspond to the synorogenic Chanic sedimentation (Chanic foreland basin). Thereafter, the stratigraphic succession underwent deformation which led to its prolonged subaerial exposure and rubefaction. In Permian times, a marine transgression gave rise to the Del Salto Formation (600 m), which is constituted by beach deposits with some aeolian reworking and which lies unconformably over the Lower Carboniferous rocks. Conglomerates (Quebrada del Alumbre Formation, 100 m) produced by an alluvial system prograded episodically into coastal areas. The Escombrera Formation (350 m) is composed of beach deposits prograding seawards. This formation probably represents the end of the Palaeozoic sedimentary record. Thereafter, a playa-lake and an alluvial fan system were generated (Quebrada de la Arena Formation). This unit (750 m) was the last infill of the Gondwanan retroarc foreland, the total thickness of which was about 4000 m.Se presentan nuevos datos sobre las unidades neopaleozoicas aflorantes en la parte occidental de la Precordillera andina. Esas unidades litoestratigráficas estan separadas por dos discordancias angulares principales asociadas al desarrollo de las orogenias Chánica (Devónico tardío-Carbonífero temprano) y Gondwánica (Carbonífero tardío-Pérmico temprano) respectivamente. Otra nueva discordancia sugiere el inicio del ciclo andino durante el Pérmico medio. La Formación Del Ratón (800 m) está constituida principalmente por conglomerados y puede dividirse en dos unidades de rango menor: la parte basal y la parte superior respectivamente. La parte basal (Miembro inferior) fue acumulada en un fiordo. La parte superior (Miembro superior) fue generada en un sistema alluvial dominado predominantemente por la acumulación de capas planas de alto régimen de flujo, mientras que la parte más alta fue depositada en un entorno de abanico deltaico (fandelta). La procedencia de los clastos y las paleocorrientes principales indican la presencia de un relieve topográfico alto y significativo, situado al O y NO de los afloramientos actuales.La Formación El Planchón (1400 m) constituida principalmente por lutitas y areniscas fue acumulada en un contexto de abanico submarino (deep-sea fan). Estos materiales predominantemente lutíticos pasan lateralmente hacia el norte a conglomerados acumulados en un ambiente sedimentario glacial. Las Formaciones Del Ratón y El Planchón corresponden a la sedimentación sinorogénica Chánica (cuenca de antepaís chánica). Posteriormente, la sucesión estratigráfica sufrió una deformación que dió lugar a una prolongada exposición subaérea y su consiguiente rubefacción. Durante el Pérmico, una transgresión marina produjo la acumulación de la Formación Del Salto (600 m), que está constituída por depósitos de playa con algún retrabajamiento eólico y que recubre discordantemente los materiales del Carbonífero inferior. Un sistema aluvial conglomerático (Formación Quebrada del Alumbre 100 m) pogradó episódicamente sobre las zonas costeras. La Formación Escombrera (350 m), que está constituída por materiales arenosos coste-ros progradantes hacia el mar, representa, muy probablemente, el final del registro sedimentario paleozoico en esta zona. Posteriormente se generó otra discordancia sobre la que se acumularon materiales arenosos en un contexto de cursos fluviales trenzados sobre los que se disponen materiales lutíticos acumulados en una ciénaga (playa-lake) que gradan, primero a cursos trenzados, luego a cursos sinousos y finalmente a abanicos aluviales (Formación Quebrada de la Arena). Esta unidad (750 m) corresponde al último relleno sedimentario de la cuenca Gondwánica de retroarco, cuya potencia es del orden de unos 4000 m.Fil: Colombo, F.. Universidad de Barcelona; EspañaFil: Limarino, Carlos Oscar. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología; ArgentinaFil: Spalletti, Luis Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; ArgentinaFil: Busquets, P. Universidad de Barcelona; EspañaFil: Cardo, R.. Secretaría de Industria y Minería. Servicio Geológico Minero Argentino; ArgentinaFil: Mendez Bedia, I. Universidad de Oviedo; EspañaFil: Heredia, N.. Instituto Geológico y Minero de España; Españ

Structure of the Southern Patagonian Andes at 49ºS, Argentina

This paper describes Late Paleozoic Gondwanan and Late Cretaceous to Early Cenozoic Andean structures in the Southern Patagonian Andes and an associated Extra-Andean region between lakes San Martín and Viedma. The study area encompasses a 200-km-long W-E section between the Patagonian icefield and the 72ºW longitude meridian, in Argentine Patagonia. The oldest structures are of Late Paleozoic age and developed through at least two deformation phases during the Gondwanan Orogeny. The first deformation phase (Dg1) includes isoclinal and N-overturned WNW trending folds and associated thrusts, including duplexes. The second deformation phase includes NNE trending open folds (Dg2). Deformation occurred in non-metamorphic to very low-grade metamorphic conditions. A spaced rough cleavage is found near the first phase fold hinges. The Eocene and Miocene Andean structural compression resulted in a N-S oriented fold and thrust belt. This belt is comprised of three morphostructural zones from W to E, with distinctive topographic altitudes and structural styles: Andean; Sub-Andean; and Extra-Andean zones. The first corresponds to the inner fold and thrust belt, while the last two are part of the outer fold and thrust belt. The Andean zone (3400–2000m above sea level) is characterized by N-S to NNE trending, E-vergent, Cenozoic reverse faults and associated minor thrusts. The northern part of the Sub- Andean zone (2000–1500m above sea level) consists of W-vergent reverse faults and some NNE open folds. The southern part of the Andean zone includes tight folds with box and kink geometries, related to thrusts at deeper levels. In the Extra-Andean zone, with maximum heights of 1500m, the deformation is less intense, and gentle folds deform the Upper Cretaceous sediments. An inherited Jurassic N-S extensional fault system imposed a strong control on this morphostructural zonation. Also the variation of the Austral Basin sedimentary thickness in the N-S direction seems to have influenced the structural styles of the outer fold and thrust belt. Those differences in sedimentary thickness may be related to S-dipping transfer zones associated to W-E Jurassic extension. In turn, the transfer zones may have been controlled by the N-vergent WNW, Dg1, Gondwanan structural fabric

Risk of miscarriage following amniocentesis and chorionic villus sampling: a systematic review of the literature

Objectives: To estimate the risk of miscarriage after amniocentesis or chorionic villus sampling (CVS) based on a systematic review of the literature. Methods: A search of MEDLINE, EMBASE, and The Cochrane Library (2000-2017) was carried out to identify studies reporting complications following CVS or amniocentesis. The inclusion criteria for the systematic review were studies reporting results from large controlled studies (n1,000 invasive procedures) and those reporting data for pregnancy loss prior to 24 weeks’ gestation. Data for cases that had invasive procedure and controls were inputted in contingency tables and risk of miscarriage was estimated for each study. Summary statistics were calculated after taking into account the weighting for each study included in the systematic review. Procedure-related risk of miscarriage was estimated as a weighted risk difference from the summary statistics for cases and controls. Results: The electronic search from the databases yielded 2,465 potential citations of which 2,431 were excluded, leaving 34 studies for full-text review. The final review included 10 studies for amniocentesis and 6 studies for CVS, which were used to estimate risk of miscarriage in pregnancies that had an invasive procedure and the control pregnancies that did not. The procedure-related risk of miscarriage following amniocentesis was 0.35% (95% confidence interval [CI]: 0.07 to 0.63) and that following CVS was 0.35% (95%C CI: -0.31 to 1.00). Conclusion: The procedure-related risks of miscarriage following amniocentesis and CVS are lower than currently quoted to women

In memoriam of Andrés Pérez-Estaún

Non

Estratigrafía y estructura de los Andes Centrales Argentinos entre los 30º y 31º de Latitud Sur

In a cross-section through the Argentine central Andes, two large groups of rocks can be distinguished: a Gondwanic (F'aleozoic) basement, and an Andean cover. The basement is constituted by manne sedimentary units, intruded by Upper Paleozoic granitoid rocks. The most important Gondwanic structures, are East verging thrust and related folds. The Andean cover has a volcanic and volcanoclastic origin with some interbedded continental sedimentary rocks. The lower Permo-Tnassic unit (Choiyoi Group) is linked to an extensional tectonic event, and a Neogene sequence is connected to a compressional tectonic event that produced the inversion of the previous extensional features. The amount of Andean shortening calculated fiom cross sections is of about 10%. Most of the shortening in the Andean Cordillera was transferred to the Precordillera through the detachment fault. The up-lift of the Pampeanas area is linked with a new lower detachment fault