Triassic igneous and sedimentary rocks exposed within the basement of the Andes were deposited in a series of rifts, and may record the early disassembly of western Pangaea. These rocks are ...sporadically exposed along almost the entire length of western South America, although reliable geochronological and isotopic data are sparse. We combine new geochronological (zircon U–Pb), isotopic (Hf, Nd) and geochemical data with stratigraphic observations to constrain the age and tectonic setting of the Mitu Rift of southern Peru. The Peruvian Mitu Rift is compared with other Triassic rifts in Colombia and Ecuador (Palanda Rift; 240–225Ma), Bolivia (Mitu Rift; Triassic), Bolivia, Chile and Argentina (e.g. Cuyo Basin; 246–230Ma), and conclusions are reached regarding the relationship between Triassic extension along the western margin of Pangaea, and the eventual formation of the Proto-Caribbean and Central Atlantic oceans. The Mitu Rift (Peru) was active during ~245–240 to ~220Ma and was synchronous with rifting along the Pacific margin of Colombia and Ecuador, along the Chilean margin and western Argentina, and probably rifting within Bolivia. Rifting north of the Huancabamba Deflection was accompanied by subduction and led to seafloor spreading, whereas rifting along the Peruvian and Chilean margins mainly occurred in the absence of subduction and terminated prior to the formation of extensive transitional crust. Extension within Peru and Chile probably occurred via a combination of transtension, steepening and detachment of an arrested slab. We propose that plate tectonic forces initiated the early break-up of Pangaea by attenuating its margins and enhancing mantle upwelling. Prolonged extension may have propagated along pre-existing weak zones that extended into the continental interior, captured melts derived from the upwelled mantle forming a LIP (e.g. Central Atlantic Magmatic Province), became hot and weak and eventually lead to the formation of a juvenile ocean (e.g. Central Atlantic).
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•The Mitu Rift (central and southern Peru) formed during ~245–240 to ~220Ma.•Middle–Late Triassic extension affected the entire western margin of S. America.•Plate margin forces initiated the early disassembly of western Pangaea.
Grenvillian crust is encountered in several basement inliers in the northern Andes of Colombia, Ecuador and Peru and is also represented as a major detrital or inherited component within ...Neoproterozoic to Paleozoic sedimentary and magmatic rocks. This review of the tectonic and geochronological record of the Grenvillian belt in the northern Andes suggests that these crustal segments probably formed on an active continental margin in which associated arc and back-arc magmatism evolved from ca. 1.25 to 1.16
Ga, possibly extending to as young as 1.08
Ga.
The lithostratigraphic and tectonic history of the Grenvillian belt in the northern Andes differs from that of the Sunsas belt on the southwest Amazonian Craton and from the Grenvillian belt of Eastern Laurentia. It is considered that this belt, along with similar terranes of Grenvillian age in Middle America and Mexico define a separate composite orogen which formed on the northwestern margin of the Amazonian Craton. Microcontinent accretion and interaction with the Sveconorwegian province on Baltica is a feasible tectonic scenario, in line with recent paleogeographic reconstructions of the Rodinian supercontinent. Although Phanerozoic tectonics may have redistributed some of these terranes, they are still viewed as para-autocthonous domains that remained in proximity to the margin of Amazonia. Paleogeographic data derived from Phanerozoic rocks suggest that some of the Colombian Grenvillian fragments were connected to northernmost Peru and Ecuador until the Mesozoic, whereas the Mexican terranes where attached to the Colombian margin until Pangea fragmentation in Late Triassic times.
Neoproterozoic Palaeogeographic reconstructions of Rodinia conventionally place the western (Proto-Andean) margin of Amazonia against the eastern (Appalachian) margin of Laurentia. Separation and ...formation of the Iapetus Ocean is generally considered to have occurred later at ∼550
Ma. We examine the U–Pb detrital zircon “fingerprint” of autochthonous rocks from the northern and central segments of the Proto-Andean margin, which formed part of the western margin of Amazonia during the Late Neoproterozoic–Phanerozoic. The Proto-Andean margin is clearly the most feasible source region for most of the zircon grains, except for a 550–650
Ma sub-population, broadly age-equivalent to the Brasiliano/Pan-African Orogeny in eastern Amazonia. No obvious source for this detritus is known in the northern and central Andes. Derivation from eastern Amazonia is considered unlikely due to the stark paucity of detritus derived from the core of the Amazonian craton. Instead, we propose that a Late Neoproterozoic magmatic belt is buried beneath the present-day Andean belt or Amazon Basin, and was probably covered during the Eocene–Oligocene. If this inferred Neoproterozoic belt was an active margin, it would record the initiation of Proto-Andean subduction and imply at least partial separation of West Gondwana from its conjugate rift margin of eastern Laurentia prior to ca. 650
Ma. This separation may be linked to the ca. 770–680
Ma A-type magmatism found on eastern Laurentia in the southern Appalachians, and on the Proto-Andean margin in the Sierra Pampeanas and the Eastern Cordillera of Peru.
This article presents a novel data encryption technique suitable for Internet of Things (IoT) applications. The cryptosystem is based on the application of a Catalan object (as a cryptographic key) ...that provides encryption based on combinatorial structures with noncrossing or nonnested matching. The experimental part of this article includes a comparative analysis of the proposed encryption method with the Catalan numbers and data encryption standard (DES) algorithm, which is performed with machine learning-based identification of the encryption method using ciphertext only. These tests showed that it is much more difficult to recognize ciphertext generated with the Catalan method than one made with the DES algorithm. System reliability depends on the quality of the key, therefore, statistical testing proposed by National Institute of Standards and Technology was also performed. Twelve standard tests, the approximate entropy measurement, and random digression complexity analysis are applied in order to evaluate the quality of the generated Catalan key. A proposal for applying this method in e-Health IoT is also given. Possibilities of applying this method in the IoT applications for smart cities data storage and processing are provided.
Abstract Background Obstructive sleep apnea (OSA) in pregnancy is associated with adverse maternal and perinatal outcomes, such as hypertensive disorders of pregnancy, gestational diabetes and ...obesity. These disorders are major causes of maternal and fetal morbidity and mortality. Methods A 12-question, web-based survey was distributed to members of the Society for Obstetric Anesthesiology and Perinatology via e-mail. Responses were collected and analyzed by Survey Monkey®. Results The survey was opened by 536/1038 recipients. The overall response rate was 285/1038 (27.5%). Respondents were mostly attending/consultant (91.2%) anesthesiologists (97.9%) from the United States (83.2%) and Canada (10.5%). Over 91% of respondents believe that OSA in pregnancy is clinically relevant and 86.8% believe that management and treatment of this condition would improve maternal and/or neonatal outcomes. However, 42.8% of respondents do not screen for OSA and 82.7% of departments do not have OSA management guidelines for pregnant women. Respondent knowledge of risk factors associated with OSA in pregnancy equated to those in the non-pregnant population. Conclusion Many clinicians agree that OSA in pregnancy is a clinically relevant issue and treatment may improve outcomes. However, routine screening for OSA and departmental guidelines for the management of pregnant women with OSA are lacking. Obstetric anesthesiologists do not readily identify risk factors specific to OSA in pregnancy.
Abstract Spinal metastases occur in up to 70% of all patients with cancer. However, only 10% are symptomatic. Before considering central neuraxial blockade in patients with malignancy, a history of ...back pain should be excluded. Anaesthetists should be aware that intrathecal and epidural injections could cause paraplegia if metastases are impinging on the spinal cord. Failure to achieve adequate sensory anaesthesia after central neuraxial blockade or presentation with postoperative paraplegia may indicate the presence of asymptomatic vertebral canal metastases. In this report, the anaesthetic management of a patient with respiratory failure and spinal metastases from a soft tissue sarcoma, requiring caesarean section is described. Sensory anaesthesia extending above a level of imminent cord compression was achieved despite loss of cerebrospinal fluid signal on magnetic resonance imaging.