Análise bioestratigráfica preliminar dos nanofósseis calcários do albiano-turoniano no leg 39/356, platô de São Paulo

O trabalho apresenta resultados bioestratigráficos preliminares com base no estudo de nanofósseis calcários recuperados em 15 amostras dispostas no intervalo basal do Leg 39/356 perfurado pelo Deep Sea Drilling Project (DSDP) na região do Platô de São Paulo. O Platô de São Paulo é uma feição fisiográfica regional submersa no Oceano Atlântico Sul, sendo que a sucessão sedimentar que abrange o Cretáceo no Site 356 é dividida em sete unidades sedimentares, e o intervalo Albiano-Turoniano, estudado neste trabalho, composto por calcários dolomíticos margosos. Para a recuperação dos nanofósseis calcários foi utilizada a metodologia conhecida como smear slide, que é padrão para estudos deste grupo fóssil. Após a etapa de preparação, as amostras foram analisadas com auxílio de um microscópio óptico Zeiss Axio ImagerA2 no Instituto Tecnológico de Micropaleontologia (ITT FOSSIL). Um total de 42 espécies de nanofósseis calcários foi recuperado, permitindo o reconhecimento de uma assembleia típica do Cretáceo, com espécies guia que permitem atribuir que a seção estudada depositou-se no intervalo Albiano-Turoniano. A ocorrência de Braarudosphaera africana, nas 12 amostras basais (intervalo de 34,52 metros), indica que a deposição destes estratos ocorreu durante o intervalo Albiano-Cenomaniano. Ao longo do restante da seção, em 3 amostras dispostas em 6 metros, foram registradas a co-ocorrência das espécies Eprolithus eptapetalus e Lithastrinus septenarius que atribuem, aos sedimentos estudados, uma idade relativa referente ao Turoniano. A análise da distribuição estratigráfica de nanofósseis calcários recuperados, integrada às datações relativas dos estratos com base neste mesmo grupo fóssil, permitem um refinamento bioestratigráfico da seção estudada, a qual abrange o intervalo Albiano-Turoniano do Platô de São Paulo. As etapas seguintes deste estudo serão o aprimoramento na identificação taxonômica dos nanofósseis calcários recuperados e análise da nanoflora calcária em amostras correspondentes à porção superior do testemunho.Fil: Rodrigues Bruno, Mauro Daniel. Universidad de Vale do Rio dos Sinos; BrasilFil: Do Monte Guerra, Rodrigo. Universidad de Vale do Rio dos Sinos; BrasilFil: Fauth, Gerson. Universidad de Vale do Rio dos Sinos; BrasilFil: Concheyro, Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaXXIII Congresso Brasileiro de PaleontologiaGramadoBrasilUniversidad de Vale do Rio dos Sino

A record of spontaneous subduction initiation in the Izu–Bonin–Mariana arc

The initiation of tectonic plate subduction into the mantle is poorly understood. If subduction is induced by the push of a distant mid-ocean ridge or subducted slab pull, we expect compression and uplift of the overriding plate. In contrast, spontaneous subduction initiation, driven by subsidence of dense lithosphere along faults adjacent to buoyant lithosphere, would result in extension and magmatism. The rock record of subduction initiation is typically obscured by younger deposits, so evaluating these possibilities has proved elusive. Here we analyse the geochemical characteristics of igneous basement rocks and overlying sediments, sampled from the Amami Sankaku Basin in the northwest Philippine Sea. The uppermost basement rocks are areally widespread and supplied via dykes. They are similar in composition and age—as constrained by the biostratigraphy of the overlying sediments—to the 52–48-million-year-old basalts in the adjacent Izu–Bonin–Mariana fore-arc. The geochemical characteristics of the basement lavas indicate that a component of subducted lithosphere was involved in their genesis, and the lavas were derived from mantle source rocks that were more melt-depleted than those tapped at mid-ocean ridges. We propose that the basement lavas formed during the inception of Izu–Bonin–Mariana subduction in a mode consistent with the spontaneous initiation of subduction

Why Are Outcomes Different for Registry Patients Enrolled Prospectively and Retrospectively? Insights from the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF).

Background: Retrospective and prospective observational studies are designed to reflect real-world evidence on clinical practice, but can yield conflicting results. The GARFIELD-AF Registry includes both methods of enrolment and allows analysis of differences in patient characteristics and outcomes that may result. Methods and Results: Patients with atrial fibrillation (AF) and ≥1 risk factor for stroke at diagnosis of AF were recruited either retrospectively (n = 5069) or prospectively (n = 5501) from 19 countries and then followed prospectively. The retrospectively enrolled cohort comprised patients with established AF (for a least 6, and up to 24 months before enrolment), who were identified retrospectively (and baseline and partial follow-up data were collected from the emedical records) and then followed prospectively between 0-18 months (such that the total time of follow-up was 24 months; data collection Dec-2009 and Oct-2010). In the prospectively enrolled cohort, patients with newly diagnosed AF (≤6 weeks after diagnosis) were recruited between Mar-2010 and Oct-2011 and were followed for 24 months after enrolment. Differences between the cohorts were observed in clinical characteristics, including type of AF, stroke prevention strategies, and event rates. More patients in the retrospectively identified cohort received vitamin K antagonists (62.1% vs. 53.2%) and fewer received non-vitamin K oral anticoagulants (1.8% vs . 4.2%). All-cause mortality rates per 100 person-years during the prospective follow-up (starting the first study visit up to 1 year) were significantly lower in the retrospective than prospectively identified cohort (3.04 [95% CI 2.51 to 3.67] vs . 4.05 [95% CI 3.53 to 4.63]; p = 0.016). Conclusions: Interpretations of data from registries that aim to evaluate the characteristics and outcomes of patients with AF must take account of differences in registry design and the impact of recall bias and survivorship bias that is incurred with retrospective enrolment. Clinical Trial Registration: - URL: http://www.clinicaltrials.gov . Unique identifier for GARFIELD-AF (NCT01090362)

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

Evolução do conhecimento biocronoestratigráfico do Cretáceo nas bacias marginais brasileiras baseado em nanofósseis calcários

BIOCHRONOSTRATIGRAPHIC KNOWLEDGE EVOLUTION IN THE BRAZILIAN CRETACEOUS MARGINAL BASINS BASED ON CAKCAREOUS NANNOFOSSILS The use of the biostratigraphy effective contributes to the resolution of stratigraphic problems, allowing the strata correlation based on the use of fossils. Its use as a standard tool in the oil exploration, provided advances in the biostratigraphic concepts and the geological knowledge. Due to the difficulty in recover macrofossils in drilled samples, microfossils are the best alternative for correlations, paleoecological studies and chronostratigraphic placement of wells. Calcareous nannofossils is one of the most important groups, because of their abundance in rocks, the wide geographic distribution, rapid speciation and the laboratory procedure. This study aims to present the importance of the biostratigraphy and the evolution of the biochronostratigraphic knowledge of the Upper Cretaceous in the Brazilian marginal basins, by means of the main biostratigraphic zonations based on calcareous nannofossils. Citation: Guerra R. do M., Tokutake L. R. 2011. Evolução do conhecimento biocronoestratigráfico do Cretáceo nas bacias marginais brasileiras baseado em nanofósseis calcários.O advento da bioestratigrafia contribuiu em grande parte para a resolução de problemas estratigráficos, possibilitando a correlação dos estratos rochosos com base na análise dos fósseis. A utilização como ferramenta padrão na indústria do petróleo propiciou um grande avanço nos conceitos da bioestratigrafia e no conhecimento geológico. Devido a dificuldade de recuperação de macrofósseis na amostragem em perfurações petrolíferas, os microfósseis transformaram-se em ótima alternativa para correlações, estudos paleoecológicos e posicionamento cronoestratigráfico de poços. Dentre os grupos mais utilizados estão os nanofósseis calcários, devido à abundância com que ocorrem nas rochas aliada à ampla distribuição geográfica, rápida especiação e ao fato de serem facilmente recuperados da matriz sedimentar e preparados em laboratório. Este trabalho busca apresentar a importância da bioestratigrafia e a evolução do conhecimento cronoestratigráfico do Cretáceo Superior nas bacias marginais brasileiras, por meio dos principais biozoneamentos propostos com nanofósseis calcários

Evolução do conhecimento biocronoestratigráfico do cretáceo nas bacias marginais brasileiras baseado em nanofósseis calcários

O advento da bioestratigrafia contribuiu em grande parte para a resolução de problemas estratigráficos, possibilitando a correlação dos estratos rochosos com base na análise dos fósseis. A utilização como ferramenta padrão na indústria do petróleo propiciou um grande avanço nos conceitos da bioestratigrafia e no conhecimento geológico. Devido a dificuldade de recuperação de macrofósseis na amostragem em perfurações petrolíferas, os microfósseis transformaram-se em ótima alternativa para correlações, estudos paleoecológicos e posicionamento cronoestratigráfico de poços. Dentre os grupos mais utilizados estão os nanofósseis calcários, devido à abundância com que ocorrem nas rochas aliada à ampla distribuição geográfica, rápida especiação e ao fato de serem facilmente recuperados da matriz sedimentar e preparados em laboratório. Este trabalho busca apresentar a importância da bioestratigrafia e a evolução do conhecimento cronoestratigráfico do Cretáceo Superior nas bacias marginais brasileiras, por meio dos principais biozoneamentos propostos com nanofósseis calcários

New latitude-based nannofossil zonations for the Campanian–Maastrichtian of the South Atlantic Ocean and their paleoceanographic implications

The global evolution of calcareous nannofossils during the Campanian–Maastrichtian interval is not fully understood, and nannofossil zonations for the central and South Atlantic Ocean are yet to be constructed. Here, we test the applicability of previous calcareous nannofossil zonations developed for other ocean basins, for biostratigraphy in the South Atlantic Ocean, and refine Campanian–Maastrichtian biostratigraphy in the region. We document calcareous nannofossil distributions at Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) sites from the high, mid and low latitudes in the South Atlantic Ocean (DSDP Sites 354, 356, 511, 525A, and 530A, and ODP Sites 690C; 700B; 661A, and 1258A). Combining nannofossil occurrences with magnetostratigraphic schemes previously constructed for some of the sites, we propose three new zonations tied to the global magnetostratigraphic chrons, with distinct bio-horizons selected at different latitudinal regions. In this study we present detailed definitions of new South Atlantic Ocean Low-latitude (SAL), South Atlantic Mid-latitude (SAM) and South Atlantic High-latitude (SAH) zonations. We identified significant diachronism of some species between latitudes throughout the Campanian and Maastrichtian. These species diachronism, mainly between zonal markers from low and mid latitudes during the late Maastrichtian, was probably related to migration patterns due to fundamental paleoceanographic changes

Calcareous nannofossils from the Santa Marta Formation (Upper Cretaceous), northern James Ross Island, Antarctic Peninsula

This study reports on the most stratigraphically extensive nannofloras yet recovered from the Lachman Crags Member of the Santa Marta Formation, James Ross Island, Antarctic Peninsula. The productive samples are dated as early Campanian. These ages are in accord with those provided by ammonites, foraminifera, ostracods and radiolarians from the same locality. The consistent and relatively abundant presence of Gephyrobiscutum diabolum throughout the productive part of the section, a species that has previously only been documented from the Falkland Plateau, extends its geographic distribution to higher latitudes, at least to the Antarctic Peninsula area.Fil: Guerra, Rodrigo Do Monte. Universidade do Vale do Rio dos Sinos; BrasilFil: Concheyro, Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Lees, Jackie. University College London; Estados UnidosFil: Fauth, Gerson. Universidade do Vale do Rio dos Sinos; BrasilFil: Carvalho, Marcelo de Araujo. Universidade Federal Do Rio de Janeiro. Museu Nacional; BrasilFil: Ramos, Renato Rodriguez Cabral. Universidade Federal Do Rio de Janeiro. Museu Nacional; Brasi

International Ocean Discovery Program Expedition 369 Preliminary Report: Australia Cretaceous Climate and Tectonics: Tectonic, paleoclimate, and paleoceanographic history of high-latitude southern margins of Australia during the Cretaceous

The tectonic and paleoceanographic setting of the Great Australian Bight (GAB) and the Mentelle Basin (MB; adjacent to Naturaliste Plateau) offered an outstanding opportunity to investigate Cretaceous and Cenozoic climate change and ocean dynamics during the last phase of breakup among remnant Gondwana continents. Sediment recovered from sites in both regions during International Ocean Discovery Program Expedition 369 will provide a new perspective on Earth\u27s temperature variation at sub-polar latitudes (60°-62°S) across the extremes of the mid-Cretaceous hot greenhouse climate and the cooling that followed. The primary goals of the expedition were to: * Investigate the timing and causes for the rise and collapse of the Cretaceous hot greenhouse climate and how this climate mode affected the climate-ocean system and oceanic biota; * Determine the relative roles of productivity, ocean temperature, and ocean circulation at high southern latitudes during Cretaceous oceanic anoxic events (OAEs); * Identify the main source regions for deep-water and intermediate-water masses in the southeast Indian Ocean and how these changed during Gondwana breakup; * Characterize how oceanographic conditions at the MB changed during the Cenozoic opening of the Tasman Passage and restriction of the Indonesian Gateway; * Resolve questions on the volcanic and sedimentary origins of the Australo-Antarctic Gulf and Mentelle Basin and provide stratigraphic control on the age and nature of the prebreakup successions. Hole U1512A in the GAB recovered a 691 m thick sequence of black claystone ranging from the early Turonian to the early Campanian. Age control is primarily based on calcareous nannofossils, but the presence of other microfossil groups provided consistent but low-resolution control. Despite the lithologic uniformity, long- and short-term variations in natural gamma ray and magnetic susceptibility intensities show cyclic alternations that suggest an orbital control of sediment deposition that will be useful for developing an astrochronology for the sequence. Sites U1513-U1516 were drilled between 850 and 3900 m water depth in the MB and penetrated 774, 517, 517, and 542 meters below seafloor (mbsf), respectively. Under a thin layer of Pleistocene-upper Miocene sediment, Site U1513 cored a succession of Cretaceous units from the Campanian to the Valanginian. Site U1514 sampled an expanded Pleistocene-Eocene sequence and terminated in the upper Albian. The Cenomanian-Turonian interval at Site U1514 recovered deformed sedimentary rocks that probably represent a detachment zone. Site U1515 is located on the west Australian margin at 850 m water depth and was the most challenging site to core because much of the upper 350 m was either chert or poorly consolidated sand. However, the prebreakup Jurassic(?) sediments interpreted from the seismic profiles were successfully recovered. Site U1516 cored an expanded Pleistocene, Neogene, and Paleogene section and recovered a complete Cenomanian/Turonian boundary interval containing five layers with high total organic carbon content. The Early Cretaceous volcanic rocks and underlying Jurassic(?) sediments cored in different parts of the MB provide information on the timing of different stages of the Gondwana breakup. The recovered cores provide sufficient new age constraints to underpin a reevaluation of the basin-wide seismic stratigraphy and tectonic models for the region