Ricardo I F Trindade

University of São Paulo | USP · Departament of Geophysics

The timing and duration of oceanic disturbances linked to Oceanic Anoxic Event (OAE) 1b, as well as the mechanisms driving anoxia and carbon burial during this period, remain subjects of debate. We conducted cyclostratigraphic analyses on magnetic susceptibility (MS) and elemental Ti and Fe series within the upper Aptian‐lower Albian interval of th...

Earth’s magnetic field exhibits a dominant dipole morphology. Notwithstanding, significant deviations from the dipole are evident today, particularly the South Atlantic Anomaly (SAA), characterized by anomalously low-field intensity and high directional variability, diminishing the field’s shielding effect. To assess the persistence of SAA-like fea...

The Neoproterozoic carbonate rocks of the Araras Group (Amazon Craton) and the Sete‐Lagoas and Salitre Formations (São Francisco Craton) share a statistically indistinguishable single‐polarity (reversed) characteristic direction. This direction is associated with paleomagnetic poles that do not align with the expected directions for primary detrita...

Speleothems are mineral deposits capable of recording detrital and/or chemical remanent magnetization at annual timescales. They can offer high‐resolution paleomagnetic records of short‐term variations in Earth's magnetic field, crucial for understanding the evolution of the dynamo. Owing to limitations on the magnetic moment sensitivity of commerc...

The recording of planetary magnetic fields is often attributed to uniformly-magnetised nanoscopic iron oxides, called single-domain. Yet, the main magnetic constituents of rocks are more complex, non-uniformly magnetised grains in single or multi-vortex states. We know little about their behaviour due to limitations in defining their precise shape...

Dating archaeological materials is essential to understand time and rate of changes in different civilizations. For this purpose, different dating methods are used in several materials, including organic remains, sediments, and ceramics. Archaeomagnetic dating is a developing dating tool that has been improving rapidly due to the advances in geomag...

Paleomagnetic data is collected from bulk samples, containing a mixture of stable and unstable magnetic particles. Recently, magnetic microscopy techniques have allowed the examination of individual magnetic grains. However, accurately determining the magnetic moments of these grains is difficult and time‐consuming due to the inherent ambiguity of...

The Ediacaran-Cambrian transition documents a critical stage in the diversification of animals. The global fossil record documents the appearance of cloudinomorphs and other shelled tubular organisms followed by non-biomineralized small carbonaceous fossils and by the highly diversified small shelly fossils between ~ 550 and 530 Ma. Here, we report...

The Rio Apa Terrane (RAT) is situated at the south end of the Amazonian Craton (AC) separated from it by the aulacogen Tucavaca belt. It encompasses basement rocks that evolved mainly during the Paleoproterozoic. Its relationship to the AC during Proterozoic is yet undefined, although geologic, geochronologic and isotopic evidence suggest it was cl...

Magnetotactic bacteria produce chains of nanoscopic iron minerals used for navigation, which can be preserved over geological timescales in the form of magnetofossils. Micrometer-sized magnetite crystals with unusual shapes suggesting a biologically controlled mineralization have been found in the geological record and termed giant magnetofossils....

Anomalous paleomagnetic data have been found worldwide during the Ediacaran period, giving rise to several non-actualistic hypothesis. In order to get more information about this period, paleomagnetic, magnetic fabric and rock magnetic studies were carried out in the Avellaneda Formation ($570-560 Ma) from two drill cores of the Alicia quarry in th...

In this study, we investigate the paleomagnetism of the basal Maieberg Formation (Namibia) cap carbonate sequence to elucidate its magnetic properties and paleolatitude of deposition, establish global correlations, and contribute to the understanding of Snowball Earth postglacial dynamics. Two distinct magnetization components, C1 and C2, were iden...

The recording of planetary magnetic fields is often attributed to uniformly-magnetised nanoscopic iron oxides, called single-domain (SD). Yet, the main magnetic constituents of rocks are more complex, non-uniformly magnetised grains in single or multi-vortex states. We know little about their behaviour due to limitations in defining their precise s...

The Neoproterozoic phosphogenic event records biotic and biogeochemical changes that seem to indicate intrinsic relationships between phosphogenesis and phosphatic fossil preservation. However, chemo-litho and biostratigraphic correlations conducted on fossiliferous, phosphatic successions of the Doushantuo Formation, South China, evidence a highly...

The late Ediacaran record encompasses frequent occurrences of 34 S-enriched pyrites, which can surpass the coexisting sulfate isotope values. Deciphering what controls this marine isotope record is important to understand its biogeochemical implications, especially considering the early metazoan evolution. We present here multiple sulfur isotope co...

Primary biological aerosol particles (PBAP, also called bioaerosols) are airborne particles from integral or pieces of biological sources. The most abundant PBAP are bacteria, which have been shown in laboratory studies to have shown efficient ice nucleation activity (INA) in the atmosphere. Therefore, a significant amount of INA bacteria was found...

Cyclostratigraphic analyses were performed on magnetic susceptibility (MS), and elemental Ti and Fe series along the upper Aptian-lower Albian interval of the Poggio le Guaine (PLG) core, a Cretaceous pelagic succession in the Umbria-Marche Basin (central Italy). This interval represents one the most detailed and complete sedimentary archives and r...

Unveiling the tempo and mode of animal evolution is necessary to understand the links between environmental changes and biological innovation. Although the earliest unambiguous metazoan fossils date to the late Ediacaran period, molecular clock estimates agree that the last common ancestor (LCA) of all extant animals emerged ~850 Ma, in the Tonian...

Carbonate rocks frequently undergo remagnetisation events, which can partially/completely erase their primary detrital remanence and introduce a secondary component through thermoviscous and/or chemical processes. Despite belonging to different basins hundreds of kilometres apart, the Neoproterozoic carbonate rocks of South America (over the Amazon...

The kinematic analysis of magmatic structures is key evidence for the tectonic settings and deformation mechanisms related to the emplacement of intrusive bodies. The Dom Feliciano Belt (DFB), southernmost Brazil, registers voluminous post-collisional magmatism during the Neoproterozoic and the Arroio do Silva Pluton (ASP) is a diorite-monzonite-sy...

The lightning induced remanent magnetization is known to leave anomalous features in rocks, with high intensity and directions that follow an approximately circular pattern. Previous works account for the effect of an atmospheric discharge similar to a magnetic pulse that induces an isothermal remanent magnetization, although, following this premis...

The Ediacaran apparent polar wander path (APWP) for the Rio de la Plata Craton was analyzed and a new alternative path is presented. This revised path was constructed considering an opposite polarity for poles older than ca. 590 Ma. This path is more consistent with that recently proposed for West Africa, whose large oscillations were attributed to...

The Tamengo Formation (Corumbá Group, midwest Brazil) is a carbonate-dominated succession of major importance to unravel the environmental and biological changes during the Ediacaran–Cambrian transition in Gondwana. Although it has been extensively studied in terms of sedimentology, isotope geochemistry, biostratigraphy, and geochronology, these st...

The mid-Cretaceous is known as the most extreme greenhouse period in the last 150 Myr and was punctuated by repeated environmental perturbations. The mid-Cretaceous was also characterized by the emplacement of major Large Igneous Provinces and the deposition of organic-rich layers known as Oceanic Anoxic Events. Here, we present a high-resolution e...

The study of magnetic minerals holds significant importance across various scientific disciplines. Magnetite nanoparticles within carbonates have garnered considerable attention in the fields of paleomagnetism, environmental studies, rock magnetism, and their implications for petrophysical investigations. As such, this scientific study was conducte...

The generation of artifacts during sample preparation must be considered in paleobiological studies, particularly during the Ediacaran and Cambrian, since such artifacts can assume forms similar to those of cloudinids and other problematic taxa commonly described in samples from these systems. Chemical reactions between hydrogen peroxide and sulfid...

Quantifying the contributions of distinct mineral populations in bulk magnetic experiments greatly enhances the analysis of environmental and rock magnetism studies. Here, we develop a new method of parametric unmixing of susceptibility components in hysteresis loops. Our approach is based on a modified Gamma‐Cauchy exponential model that accounts...

Extensive phosphorite deposition is observed in the Neoproterozoic after a prolonged hiatus during most of the Mesoproterozoic era. This event is thought to represent an important record of major palaeoenvironmental, palaeoceanographic and biotic changes that shaped Neoproterozoic ecosystems, suggesting close relationships between phosphogenesis an...

Palaeointensity data from the Precambrian are key to understanding the timing of the Earth’s Inner Core Nucleation (ICN). Due to the scarcity of data, the ICN timing is still poorly constrained and is thought to have occurred between 2500 to 500 Ma. Numerical dynamo simulation models predict an increase in entropy, a stronger driving force for conv...

Magnetostratigraphy is a powerful technique for high-resolution stratigraphic correlation and accurate dating of the polarity history of the magnetic field. Up to now, magnetostratigraphic studies have been underutilized in Ediacaran successions. Here, we present a magnetostratigraphy coupled with a carbon isotope study in Ediacaran Avellaneda Form...

Paleomagnetic data are usually obtained from whole cylindric samples, where the signal results from the sum of magnetic moments from hundreds of thousands to millions of magnetic particles within the sample volume. This usually includes both stable and unstable remanence carriers.Recently, magnetic microscopy techniques allowed the investigation of...

Quantifying the contributions of distinct mineral populations in bulk magnetic experiments greatly enhances the analysis of environmental and rock magnetism studies. Here we develop a new method of parametric unmixing of susceptibility components in hysteresis loops. Our approach is based on a modified Gamma-Cauchy exponential model, that accounts...

Palaeosecular variation (PSV) determinations and studies of the geometry of the Earth’s main magnetic field provide important information about the field evolution, and to constrain numerical geodynamo models. Palaeomagnetic directional data from lava flows over the last few million years is of particular interest because the regional and global te...

The Neoproterozoic-Paleozoic transition was marked by profound modifications in the Earth-Life system, as evidenced by intense perturbations in biogechemical cycles and the appearance of complex macroscopic life. Many questions remain regarding the relationship and feedback between the biotic and abiotic processes that operated in that period, part...

We revisit the discussion on the geological processes able to remagnetize vast extensions of intracratonic basins. The main hypotheses for these processes involve: (1) external warm fluids, (2) hydrocarbon maturation, or (3) burial diagenesis and clay minerals transformation. Here we combine classical rock magnetic properties, with micro-to-nanosca...

We present new absolute archaeointensity data from six archaeological sites situated in the Okayama Prefecture, Japan. The materials studied are well-dated fragments from pottery, ceramic coffins and haniwa artifacts. Their ages range from 160 AD to 675 AD, covering the Late Yayoi and Kofun periods. Rock magnetic experiments suggest the presence of...

Abstract: The Neoproterozoic Era was one of the periods of greatest variation in Earth's external and internal environments in the Planet's history. Lithological and geochemical data show that there were several extreme climatic variations in this period, with a possible advance of the polar ice caps to equatorial latitudes. The position of contine...

High-temporal-resolution paleomagnetic datasets are critical for understanding episodes of short-term geomagnetic field instability, such as excursions, onset of reversals, and spikes. Together with geodynamic modeling, they help in the interpretation of changes in the physical environment of the core and at the core-mantle boundary. Speleothems ar...

A paleomagnetic and rock magnetic study was carried out in the Ediacaran Avellaneda (∼570 Ma) and Cerro Negro (∼555 Ma) Formations belonging to the La Providencia Group, in the upper part of the Neoproterozoic sedimentary cover of the Tandilia region, in the Río de la Plata craton. The Avellaneda Formation was studied at outcrop level and in three...

Post-collisional reversely zoned plutons occurring in the Araçuaí belt frequently show basic cores enveloped by felsic rocks, with intense magma mingling/mixing features. The Venda Nova (VN) pluton presents, in addition to its mafic core composed of gabbronorites and surrounded by syenomonzonites, a narrow ring of charnockite and norite. The Venda...

Explosive volcanism and oceanic crust generation are key aspects to understanding the break-up history of the Rodinia. Its impact on the extreme glaciations of the Cryogenian was marked by ocean chemistry fluctuations in these times, which are still poorly known and preserved in western Gondwana. Here we describe in detail and provide a series of U...

Featuring 3000 km‐long large and hot orogen, the Mantiqueira Province provides a rare opportunity to study process of gravitational collapse at mid to deep crustal levels. Distinct but contemporary (~500 Ma) post‐collisional intrusions show structures and anisotropy of magnetic susceptibility (AMS) fabrics related to their emplacements, recording d...

O campo magnético de Marte não possui componentes nucleares, todavia, apresenta diversas anomalias sem padrão dipolar espalhadas principalmente no hemisfério sul do planeta, com valores de magnetização crustal que são cerca de 100 vezes mais intensos que os observados na Terra. A distribuição de anomalias magnéticas marcianas pode ser explicada por...

Lake and lagoon sediments are important recorders of the Earth's magnetic field variations. However, the Southern Hemisphere, particularly the South American continent, contributes only a small fraction of the global paleosecular variation (PSV) and relative paleointensity data, which hinders a better understanding of the global PSV. Moreover, the...

Children's exposure to air pollution affects both their health and learning skills. Fine and ultrafine particulate matter (PM2.5, PM1), notably issued from traffic sources in urban centers, belong to the most potential harmful health hazards. However their monitoring and the society's awareness on their dangers need to be consolidated. In this stud...

Improvements in the spatial and temporal coverage of paleomagnetic data are essential to better evaluate paleofield behaviour over the past 10 Myr, especially due to data scarcity at low latitudes in the South American region. Here, we provide new Pleistocene-Holocene (0–2 Ma age interval) paleodirectional data from three volcanic systems (Doña Jua...

The sedimentary evolution of the Bambuí foreland basin system in the interior of West Gondwana is marked by periods of connection and isolation from the global ocean during the late Neoproterozoic and early Paleozoic. To understand the link between these periods and seawater redox conditions, we present an integrated study of trace-metal geochemist...

The Corumbá Group is a Neoproterozoic succession of terrigenous and carbonate sedimentary rocks located at the southern Paraguay Belt, central Brazil. The upper units of the Corumbá Group include the Ediacaran carbonate Bocaina and Tamengo formations, whose limit is characterized by polymictic breccias recognized in several sites from Corumbá to Se...

The study of plutonic rocks is an important tool for unravelling the tectonic conditions of any area. The Arroio do Silva Pluton (ASP), in southernmost Brazil, comprises a syenite-monzonite-diorite association from Neoproterozoic post-collisional setting. Despite being well characterized with petrological and geochemical data, this association of r...

The Aptian was characterized by dramatic tectonic, oceanographic, climatic and biotic changes and its record is punctuated by Oceanic Anoxic Events (OAEs). The timing and duration of these events are still contentious, particularly the age of the Barremian-Aptian boundary. This study presents a cyclostratigraphic evaluation of a high-resolution mul...

The Neoproterozoic included changes in oceanic redox conditions, the configuration of continents and climate, extreme ice ages (Sturtian and Marinoan), and the rise of complex life forms. A much-debated topic in geobiology concerns the influence of atmospheric oxygenation on Earth and the origin and diversification of animal lineages, with the most...

Speleothems can provide high-quality continuous records of the direction and relative paleointensity of the geomagnetic field, combining high precision dating (with U-Th method) and rapid lock-in of their detrital magnetic particles during calcite precipitation. Paleomagnetic results for a mid-to-late Holocene stalagmite from Dona Benedita Cave in...

Here, we discuss the role of the main South American cratonic units in the Columbia and Rodinia supercontinents, and Gondwana megacontinent. According to paleomagnetic and geological data Amazonia and West Africa were linked to Baltica, Laurentia and Siberia forming West Columbia at ca. 1.78-1.75 Ga. The 1.78 to 1.42 Ga paleomagnetic data for Amazo...